World Library  
Flag as Inappropriate
Email this Article

Leptin

Article Id: WHEBN0000214938
Reproduction Date:

Title: Leptin  
Author: World Heritage Encyclopedia
Language: English
Subject: Obesity, Leptin receptor, Hypothalamus, Adiponectin, Eating disorder
Collection: Mutated Genes, Obesity, Peptide Hormones
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Leptin

Leptin
PDB rendering based on 1ax8.
Available structures
PDB Ortholog search: PDBe, RCSB
Identifiers
Symbols  ; LEPD; OB; OBS
External IDs GeneCards:
RNA expression pattern
Orthologs
Species Human Mouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)
RefSeq (protein)
Location (UCSC)
PubMed search
Leptin
Structure of the obese protein leptin-E100.[1]
Identifiers
Symbol Leptin
Pfam PF02024
Pfam clan CL0053
InterPro IPR000065
SCOP 1ax8
SUPERFAMILY 1ax8

Leptin (from Greek λεπτός leptos, "thin"), the "satiety hormone,"[1] is a hormone made by adipose cells that helps to regulate energy balance by inhibiting hunger. Leptin is opposed by the actions of the hormone ghrelin, the "hunger hormone". Both hormones act on receptors in the arcuate nucleus of the hypothalamus to regulate appetite to achieve energy homeostasis.[2] In obesity, a decreased sensitivity to leptin occurs, resulting in an inability to detect satiety despite high energy stores.[3]

Although regulation of fat stores is deemed to be the primary function of leptin, it also plays a role in other physiological processes, as evidenced by its multiple sites of synthesis other than fat cells, and the multiple cell types beside hypothalamic cells that have leptin receptors. Many of these additional functions are yet to be defined.[4][5][6][7][8][9]

Contents

  • Identification of the gene 1
  • Recognition of scientific advances 2
  • Location of gene and structure of hormone 3
  • Mutations 4
    • Nonsense 4.1
    • Frameshift 4.2
    • Polymorphisms 4.3
    • Transversion 4.4
  • Sites of synthesis 5
  • Blood levels 6
    • Physiologic variation 6.1
    • In specific conditions 6.2
    • Mutant leptins 6.3
  • Effects 7
    • Central (hypothalamic) 7.1
    • Peripheral (non-hypothalamic) 7.2
      • Circulatory system 7.2.1
      • Fetal lung 7.2.2
      • Reproductive system 7.2.3
        • Ovulatory cycle 7.2.3.1
        • Pregnancy 7.2.3.2
        • Lactation 7.2.3.3
        • Puberty 7.2.3.4
      • Bone 7.2.4
      • Brain 7.2.5
      • Immune system 7.2.6
  • Role in obesity and weight loss 8
    • Obesity 8.1
    • Response to weight loss 8.2
  • Therapeutic use 9
    • Leptin 9.1
    • Analog metreleptin 9.2
  • Notes 10
  • See also 11
  • Some Schemes 12
  • References 13
  • External links 14

Identification of the gene

In 1950, a non-obese mouse colony being studied at the Jackson Laboratory produced a strain of obese offspring, suggesting that a mutation had occurred in a hormone regulating hunger and energy expenditure. Mice homozygous for the so-called ob mutation (ob/ob) ate voraciously and were massively obese.[10] In the 1960s, a second mutation causing obesity and a similar phenotype was identified by Douglas Coleman, also at the Jackson Laboratory, and was named diabetes (db), as both ob/ob and db/db were obese.[11][12][13] In 1990 Rudolph Leibel and Jeffrey M. Friedman reported mapping of the ob gene.[14][15][16] Consistent with Coleman’s and Leibel's hypothesis, several subsequent studies from Leibel's and Friedman’s labs and other groups confirmed that the ob gene encoded a novel hormone that circulated in blood and that could suppress food intake and body weight in ob and wild type mice, but not in db mice.[4][5][6][7] In 1994, Friedman's laboratory reported the identification of the gene.[13] In 1995, Jose F. Caro's laboratory provided evidence that the mutations in the mouse ob gene did not occur in humans. Furthermore since ob gene expression was increased, not decreased, in human obesity, it suggested resistance to leptin to be a possibility.[8] At the suggestion of Roger Guillemin, Friedman named this new hormone "leptin" from the Greek lepto meaning thin.[4][17] Leptin was the first fat cell-derived hormone (adipokine) to be discovered.[18] Subsequent studies in 1995 confirmed that the db gene encodes the leptin receptor, and that it is expressed in the hypothalamus, a region of the brain known to regulate the sensation of hunger and body weight.[19][20][21][22]

Recognition of scientific advances

Coleman and Friedman have been awarded numerous prizes acknowledging their roles in discovery of leptin, including the Gairdner Foundation International Award (2005),[23] the Shaw Prize (2009),[24] the Lasker Award,[25] the BBVA Foundation Frontiers of Knowledge Award[26] and the King Faisal International Prize,[27] Leibel has not received the same level of recognition from the discovery because he was omitted as a co-author of a scientific paper published by Friedman that reported the discovery of the gene. The various theories surrounding Friedman’s omission of Leibel and others as co-authors of this paper have been presented in a number of publications, including Ellen Ruppel Shell’s 2002 book The Hungry Gene.[28][29]

The discovery of leptin also is documented in a series of books including Fat: Fighting the Obesity Epidemic by Robert Pool,[30] The Hungry Gene by Ellen Ruppel Shell, and Rethinking Thin: The New Science of Weight Loss and the Myths and Realities of Dieting by Gina Kolata.[31][32] Fat: Fighting the Obesity Epidemic and Rethinking Thin: The New Science of Weight Loss and the Myths and Realities of Dieting review the work in the Friedman laboratory that led to the cloning of the ob gene, while The Hungry Gene draws attention to the contributions of Leibel.

Location of gene and structure of hormone

The Ob(Lep) gene (Ob for obese, Lep for leptin) is located on chromosome 7 in humans.[33] Human leptin is a 16-kDa protein of 167 amino acids

Mutations

A human mutant leptin was first described in 1997,[34] and subsequently six additional mutations were described. All of those affected were from Eastern countries; and all had variants of leptin not detected by the standard immunoreactive technique, so leptin levels were low or undetectable. The most recently described eighth mutation reported in January 2015, in a child with Turkish parents, is unique in that it is detected by the standard immunoreactive technique, so leptin levels are elevated; but the leptin does not turn on the leptin receptor, so the patient has functional leptin deficiency.[35] These eight mutations all cause extreme obesity in infancy, with hyperphagia.[35]

Nonsense

A nonsense mutation in the leptin gene that results in a stop codon and lack of leptin production was first observed in mice in 1950. In the mouse gene, arginine-105 is encoded by CGA and only requires one nucleotide change to create the stop codon TGA. The corresponding amino acid in humans is encoded by the sequence CGG and would require two nucleotides to be changed to produce a stop codon, which is much less likely to happen.[8]

Frameshift

A recessive frameshift mutation resulting in a reduction of leptin has been observed in two consanguineous children with juvenile obesity.

Polymorphisms

A Human Genome Equivalent (HuGE) review in 2004 looked at studies of the connection between genetic mutations affecting leptin regulation and obesity. They reviewed a common polymorphism in the leptin gene (A19G; frequency 0.46), three mutations in the leptin receptor gene (Q223R, K109R and K656N) and two mutations in the PPARG gene (P12A and C161T). They found no association between any of the polymorphisms and obesity.[36]

A 2006 study found a link between the common LEP-4548 G/A phenotype and morbid obesity in Taiwanese aborigines,[37][38] but a 2014 meta-analysis did not,[39] however, this polymorphism has been associated with weight gain in patients taking antipsychotics.[40][41][42]

The LEP-2548 G/A polymorphism has been linked with an increased risk of prostate cancer,[43] gestational diabetes,[44] and osteoporosis.[45]

Other rare polymorphisms have been found but their association with obesity are not consistent.[36]

Transversion

A single case of a homozygous transversion mutation of the gene encoding for leptin was reported in January 2015.[35] It leads to functional leptin deficiency with high leptin levels in circulation. The transversion of (c.298G → T) changed aspartic acid to tyrosine at position 100 (p.D100Y). The mutant leptin could neither bind to nor activate the leptin receptor in vitro, nor in leptin-deficient mice in vivo. It was found in a two-year-old boy with extreme obesity with recurrent ear and pulmonary infections. Treatment with metreleptin led to "rapid change in eating behavior, a reduction in daily energy intake, and substantial weight loss".[35]

Sites of synthesis

Leptin is produced primarily in the adipocytes of white adipose tissue. It also is produced by brown adipose tissue, placenta (syncytiotrophoblasts), ovaries, skeletal muscle, stomach (the lower part of the fundic glands), mammary epithelial cells, bone marrow,[46]gastric chief cells and P/D1 cells.[47]

Blood levels

Leptin circulates in blood in free form and bound to proteins.[48]

Physiologic variation

Leptin levels vary exponentially, not linearly, with fat mass.[49][50] Leptin levels in blood are higher between midnight and early morning, perhaps suppressing appetite during the night.[51] The diurnal rhythm of blood leptin levels may be modified by meal-timing.[52]

In specific conditions

In humans, many instances are seen where leptin dissociates from the strict role of communicating nutritional status between body and brain and no longer correlates with body fat levels:

  • Leptin level is decreased after short-term fasting (24–72 hours), even when changes in fat mass are not observed.[53][54][55]
  • Leptin plays a critical role in the adaptive response to starvation.[56][57]
  • In obese patients with obstructive sleep apnea, leptin level is increased, but decreased after the administration of continuous positive airway pressure.[58][59] In non-obese individuals, however, restful sleep (i.e., 8–12 hours of unbroken sleep) can increase leptin to normal levels.
  • Serum level of leptin is reduced by sleep deprivation.[60][61]
  • Leptin level is increased by perceived emotional stress.[62]
  • Leptin level is decreased by increases in testosterone levels and increased by increases in estrogen levels.[63]
  • Leptin level is chronically reduced by physical exercise training.[64][65][66]
  • Leptin release is increased by dexamethasone.[67]
  • Leptin level is increased by insulin.[68]
  • Leptin levels are paradoxically increased in obesity.[69]

Mutant leptins

All known leptin mutations except one are associated with low to undetectable immunoreactive leptin blood levels. The exception is a mutant leptin reported in January 2015 which is not functional, but is detected with standard immunoreactive methods. It was found in a massively obese 2-1/2-year-old boy who had high levels of circulating leptin which had no effect on leptin receptors, so he was functionally leptin-deficient.[35]

Effects

Central (hypothalamic)

Two white mice both with similar sized ears, black eyes, and pink noses: The body of the mouse on the left, however, is about three times the width of the normal-sized mouse on the right.
A comparison of a mouse unable to produce leptin, resulting in obesity (left), and a normal mouse (right)

It is important to recognize that the terms central, primary, and direct are not used interchangeably: Central vs peripheral refers to hypothalamic vs non-hypothalamic location of action of leptin; direct vs indirect refers to whether there is no intermediary, or there is an intermediary in the mode of action of leptin; and primary vs secondary is an arbitrary description of a particular function of leptin.[70]

Leptin acts on receptors in the lateral hypothalamus to inhibit hunger and the medial hypothalamus to stimulate satiety.[71]

  • In the lateral hypothalamus, leptin inhibits hunger[72] by
    • counteracting the effects of neuropeptide Y, a potent hunger promoter secreted by cells in the gut and in the hypothalamus
    • counteracting the effects of anandamide, another potent hunger promoter that binds to the same receptors as THC
  • In the medial hypothalamus, leptin stimulates satiety[73] by
    • promoting the synthesis of α-MSH, a hunger suppressant

Thus, a lesion in the lateral hypothalamus causes anorexia (due to a lack of hunger signals) and a lesion in the medial hypothalamus causes excessive hunger (due to a lack of satiety signals).[71] This appetite inhibition is long-term, in contrast to the rapid inhibition of hunger by cholecystokinin (CCK) and the slower suppression of hunger between meals mediated by PYY3-36. The absence of leptin (or its receptor) leads to uncontrolled hunger and resulting obesity. Fasting or following a very-low-calorie diet lowers leptin levels.[74][75][76][77] Leptin levels change more when food intake decreases than when it increases.[78] The dynamics of leptin due to an acute change in energy balance may be related to appetite and eventually, to food intake rather than fat stores.[79][80]

  • It controls food intake and energy expenditure by acting on receptors in the mediobasal hypothalamus.[81]

Leptin binds to neuropeptide Y (NPY) neurons in the arcuate nucleus in such a way as to decrease the activity of these neurons. Leptin signals to the hypothalamus which produces a feeling of satiety. Moreover, leptin signals may make it easier for people to resist the temptation of foods high in calories.[82]

Leptin receptor activation inhibits neuropeptide Y (NPY) and agouti-related peptide (AgRP), and activates α-melanocyte-stimulating hormone (α-MSH). The NPY neurons are a key element in the regulation of hunger; small doses of NPY injected into the brains of experimental animals stimulates feeding, while selective destruction of the NPY neurons in mice causes them to become anorexic. Conversely, α-MSH is an important mediator of satiety, and differences in the gene for the α-MSH receptor are linked to obesity in humans.

Leptin interacts with six types of receptors (Ob-Ra–Ob-Rf, or LepRa-LepRf), which in turn are encoded by a single gene, LEPR.[83] Ob-Rb is the only receptor isoform that can signal intracellularly via the Jak-Stat and MAPK signal transduction pathways,[84] and is present in hypothalamic nuclei.[85]

Generally, leptin is thought to enter the brain at the choroid plexus, where the intense expression of a form of leptin receptor molecule could act as a transport mechanism.[86]

Once leptin has bound to the Ob-Rb receptor, it activates the stat3, which is phosphorylated and travels to the nucleus to effect changes in gene expression, one of the main effects being the down-regulation of the expression of endocannabinoids, responsible for increasing hunger.[87] In response to leptin, receptor neurons have been shown to remodel themselves, changing the number and types of synapses that fire onto them.

Increased levels of melatonin causes a downregulation of leptin,[88] however, melatonin also appears to increase leptin levels in the presence of insulin, therefore causing a decrease in appetite during sleeping.[89] Partial sleep deprivation has also been associated with decreased leptin levels.[90]

Mice with type 1 diabetes treated with leptin or leptin plus insulin, compared to insulin alone had better metabolic profiles: blood sugar did not fluctuate so much; cholesterol levels decreased; less body fat formed.[91]

Peripheral (non-hypothalamic)

Non-hypothalamic targets of leptin are referred to as peripheral targets, in contrast to the hypothalamic target which is the central target. Leptin receptors are found on a wide range of cell types. There is a different relative importance of central and peripheral leptin interactions under different physiologic states, and variations between species.[46] In the periphery leptin is a modulator of energy expenditure, modulator between fetal and maternal metabolism, permissive factor in puberty, activator of immune cells, activator of beta islet cells, and a growth factor. Further, it interacts with other hormones and energy regulators: insulin, glucagon, insulin-like growth factor, growth hormone, glucocorticoids, cytokines, and metabolites.[46]

Circulatory system

The role of leptin/leptin receptors in modulation of T cell activity in the immune system was shown in experimentation with mice. It modulates the immune response to atherosclerosis, of which obesity is a predisposing factor.[92]

Exogenous leptin can promote angiogenesis by increasing vascular endothelial growth factor levels.

Hyperleptinemia produced by infusion or adenoviral gene transfer decreases blood pressure in rats.[93][94]

Leptin microinjections into the nucleus of the solitary tract (NTS) have been shown to elicit sympathoexcitatory responses, and potentiate the cardiovascular responses to activation of the chemoreflex.[95]

Fetal lung

In fetal lung, leptin is induced in the alveolar interstitial fibroblasts ("lipofibroblasts") by the action of PTHrP secreted by formative alveolar epithelium (endoderm) under moderate stretch. The leptin from the mesenchyme, in turn, acts back on the epithelium at the leptin receptor carried in the alveolar type II pneumocytes and induces surfactant expression, which is one of the main functions of these type II pneumocytes.[96]

Reproductive system

Ovulatory cycle

In mice, and to a lesser extent in humans, leptin is required for male and female fertility. Ovulatory cycles in females are linked to energy balance (positive or negative depending on whether a female is losing or gaining weight) and energy flux (how much energy is consumed and expended) much more than energy status (fat levels). When energy balance is highly negative (meaning the woman is starving) or energy flux is very high (meaning the woman is exercising at extreme levels, but still consuming enough calories), the ovarian cycle stops and females stop menstruating. Only if a female has an extremely low body fat percentage does energy status affect menstruation. Leptin levels outside an ideal range may have a negative effect on egg quality and outcome during in vitro fertilization.[97] Leptin is involved in reproduction by stimulating gonadotropin-releasing hormone from the hypothalamus.[98]

Pregnancy

The placenta produces leptin.[99] Leptin levels rise during pregnancy and fall after childbirth. Leptin is also expressed in fetal membranes and the uterine tissue. Uterine contractions are inhibited by leptin.[100] Leptin plays a role in hyperemesis gravidarum (severe morning sickness of pregnancy),[101] in polycystic ovary syndrome[102] and hypothalamic leptin is implicated in bone growth in mice.[103]

Lactation

Immunoreactive leptin has been found in human breast milk; and leptin from mother's milk has been found in the blood of suckling infant animals.[104]

Puberty

Leptin along with kisspeptin controls the onset of puberty.[105] High levels of leptin, as usually observed in obese females, can trigger neuroendocrine cascade resulting in early menarche.[106] This may eventually lead to shorter stature as oestrogen secretion starts during menarche and causes early closure of epiphyses.

Bone

Leptin's ability to regulate bone mass was first recognized in 2000.[107] Leptin can affect bone metabolism via direct signalling from the brain. Leptin decreases cancellous bone, but increases cortical bone. This "cortical-cancellous dichotomy" may represent a mechanism for enlarging bone size, and thus bone resistance, to cope with increased body weight.[108]

Bone metabolism can be regulated by central sympathetic outflow, since sympathetic pathways innervate bone tissue.[109] A number of brain-signalling molecules (neuropeptides and neurotransmitters) have been found in bone, including adrenaline, noradrenaline, serotonin, calcitonin gene-related peptide, vasoactive intestinal peptide and neuropeptide Y.[109][110] Leptin binds to its receptors in the hypothalamus, where it acts through the sympathetic nervous system to regulate bone metabolism.[111] Leptin may also act directly on bone metabolism via a balance between energy intake and the IGF-I pathway.[108][112] There is a potential for treatment of diseases of bone formation - such as impaired fracture healing - with leptin.[113]

Brain

Leptin receptors are expressed not only in the hypothalamus but also in other brain regions, particularly in the hippocampus. Thus some leptin receptors in the brain are classified as central (hypothalamic) and some as peripheral (non-hypothalamic).

  • Deficiency of leptin has been shown to alter brain proteins and neuronal functions of obese mice which can be restored by leptin injection.[114]
  • In humans, low circulating plasma leptin has been associated with cognitive changes associated with anorexia,[115] depression, and HIV.[116]
  • Studies in transgenic mouse models of Alzheimer's disease have shown that chronic administration of leptin can ameliorate brain pathology and improve cognitive performance,[117] by reducing b-amyloid and hyperphosphorylated Tau,[118][119] two hallmarks of Alzheimer's pathology.

Immune system

Factors that acutely affect leptin levels are also factors that influence other markers of inflammation, e.g., testosterone, sleep, emotional stress, caloric restriction, and body fat levels. While it is well-established that leptin is involved in the regulation of the inflammatory response,[120][121][122] it has been further theorized that leptin's role as an inflammatory marker is to respond specifically to adipose-derived inflammatory cytokines.

In terms of both structure and function, leptin resembles IL-6 and is a member of the cytokine superfamily.[1][121][123] Circulating leptin seems to affect the HPA axis, suggesting a role for leptin in stress response.[124] Elevated leptin concentrations are associated with elevated white blood cell counts in both men and women.[125]

Similar to what is observed in chronic inflammation, chronically elevated leptin levels are associated with obesity, overeating, and inflammation-related diseases, including hypertension, metabolic syndrome, and cardiovascular disease. While leptin is associated with body fat mass, however, the size of individual fat cells, and the act of overeating, it is interesting that it is not affected by exercise (for comparison, IL-6 is released in response to muscular contractions). Thus, it is speculated that leptin responds specifically to adipose-derived inflammation.[126] Leptin is a pro-angiogenic, pro-inflammatory and mitogenic factor, the actions of which are reinforced through crosstalk with IL-1 family cytokines in cancer.[127]

Taken as such, increases in leptin levels (in response to caloric intake) function as an acute pro-inflammatory response mechanism to prevent excessive cellular stress induced by overeating. When high caloric intake overtaxes the ability of fat cells to

  • Leptin: Your brain, appetite and obesity by the British Society of Neuroendocrinology
  • Leptin by Colorado State University - nice illustrations, but last updated 1998
  • Leptin at 3Dchem.com, description and structure diagrams

External links

  1. ^ a b Zhang F, Basinski MB, Beals JM, Briggs SL, Churgay LM, Clawson DK, DiMarchi RD, Furman TC, Hale JE, Hsiung HM, Schoner BE, Smith DP, Zhang XY, Wery JP, Schevitz RW (May 1997). "Crystal structure of the obese protein leptin-E100". Nature 387 (6629): 206–9.  
  2. ^ Brennan AM, Mantzoros CS (2006). "Drug Insight: the role of leptin in human physiology and pathophysiology--emerging clinical applications". Nat Clin Pract Endocrinol Metab 2 (6): 318–27.  
  3. ^ Pan H, Guo J, Su Z (May 2014). "Advances in understanding the interrelations between leptin resistance and obesity". Physiology & Behavior 130: 157–169.  
  4. ^ a b c Halaas JL, Gajiwala KS, Maffei M, Cohen SL, Chait BT, Rabinowitz D, Lallone RL, Burley SK, Friedman JM (July 1995). "Weight-reducing effects of the plasma protein encoded by the obese gene". Science 269 (5223): 543–6.  
  5. ^ a b Campfield LA, Smith FJ, Guisez Y, Devos R, Burn P (July 1995). "Recombinant mouse OB protein: evidence for a peripheral signal linking adiposity and central neural networks". Science 269 (5223): 546–9.  
  6. ^ a b Pelleymounter MA, Cullen MJ, Baker MB, Hecht R, Winters D, Boone T, Collins F (July 1995). "Effects of the obese gene product on body weight regulation in ob/ob mice". Science 269 (5223): 540–3.  
  7. ^ a b Maffei M, Halaas J, Ravussin E, Pratley RE, Lee GH, Zhang Y, Fei H, Kim S, Lallone R, Ranganathan S (November 1995). "Leptin levels in human and rodent: measurement of plasma leptin and ob RNA in obese and weight-reduced subjects". Nat. Med. 1 (11): 1155–61.  
  8. ^ a b c Considine RV, Considine EL, Williams CJ, Nyce MR, Magosin SA, Bauer TL, Rosato EL, Colberg J, Caro JF (June 1995). "Evidence against either a premature stop codon or the absence of obese gene mRNA in human obesity". J. Clin. Invest. 95 (6): 2986–8.  
  9. ^ a b Considine RV, Sinha MK, Heiman ML, Kriauciunas A, Stephens TW, Nyce MR, Ohannesian JP, Marco CC, McKee LJ, Bauer TL (1996). "Serum immunoreactive-leptin concentrations in normal-weight and obese humans". N. Engl. J. Med. 334 (5): 292–5.  
  10. ^ Dickie MM, Lane PW (1957). "Plus letter to Roy Robinson 7/7/70". Mouse News Lett. (17): 52. 
  11. ^ Bahary N, Siegel DA, Walsh J, Zhang Y, Leopold L, Leibel R, Proenca R, Friedman JM (September 1993). "Microdissection of proximal mouse chromosome 6: identification of RFLPs tightly linked to the ob mutation". Mamm. Genome 4 (9): 511–5.  
  12. ^ Friedman JM, Leibel RL, Siegel DS, Walsh J, Bahary N (December 1991). "Molecular mapping of the mouse ob mutation". Genomics 11 (4): 1054–62.  
  13. ^ a b Zhang Y, Proenca R, Maffei M, Barone M, Leopold L, Friedman JM (December 1994). "Positional cloning of the mouse obese gene and its human homologue". Nature 372 (6505): 425–32.  
  14. ^ Leibel RL, Bahary N, Friedman JM (January 1990). "Genetic variation and nutrition in obesity: approaches to the molecular genetics of obesity". World Rev Nutr Diet. 63 (1): 90–101.  
  15. ^ Bahary N, Leibel RL, Joseph L, Friedman JM (November 1990). "Molecular mapping of the mouse db mutation". Proc Natl Acad Sci U S A 87 (21): 8642–6.  
  16. ^ Leibel RL, Bahary N, Friedman JM (January 1993). "Strategies for the molecular genetic analysis of obesity in humans". Crit Rev Food Sci Nutr. 33 (4–5): 351–58.  
  17. ^ Neill US (1 October 2010). "Leaping for leptin: the 2010 Albert Lasker Basic Medical Research Award goes to Douglas Coleman and Jeffrey M. Friedman". Journal of Clinical Investigation 120 (10): 3413–3418.  
  18. ^ Conde J, Scotece M, Gómez R, López V, Gómez-Reino JJ, Lago F, Gualillo O (2011). "Adipokines: biofactors from white adipose tissue. A complex hub among inflammation, metabolism, and immunity". BIOFACTORS 37 (6): 413–420.  
  19. ^ Tartaglia LA, Dembski M, Weng X, Deng N, Culpepper J, Devos R, Richards GJ, Campfield LA, Clark FT, Deeds J, Muir C, Sanker S, Moriarty A, Moore KJ, Smutko JS, Mays GG, Wool EA, Monroe CA, Tepper RI (December 1995). "Identification and expression cloning of a leptin receptor, OB-R". Cell 83 (7): 1263–71.  
  20. ^ Chen H, Charlat O, Tartaglia LA, Woolf EA, Weng X, Ellis SJ, Lakey ND, Culpepper J, Moore KJ, Breitbart RE, Duyk GM, Tepper RI, Morgenstern JP (February 1996). "Evidence that the diabetes gene encodes the leptin receptor: identification of a mutation in the leptin receptor gene in db/db mice". Cell 84 (3): 491–5.  
  21. ^ Lee GH, Proenca R, Montez JM, Carroll KM, Darvishzadeh JG, Lee JI, Friedman JM (February 1996). "Abnormal splicing of the leptin receptor in diabetic mice". Nature 379 (6566): 632–5.  
  22. ^ Chua SC, Chung WK, Wu-Peng XS, Zhang Y, Liu SM, Tartaglia L, Leibel RL (February 1996). "Phenotypes of mouse diabetes and rat fatty due to mutations in the OB (leptin) receptor". Science 271 (5251): 994–6.  
  23. ^ Bonner J (2005). "Jeffrey Friedman, discoverer of leptin, receives Gairdner, Passano awards". Newswire. The Rockefeller University. 
  24. ^ News-Medical "Jeffrey Friedman receives Shaw Prize for discovery of leptin" . News-Medical.net. 2009. 
  25. ^ "The Lasker Foundation – 2010 Awards". Lasker Foundation. 2010. 
  26. ^ "BBVA Foundation Frontiers of Knowledge Awards". BBVA Foundation. 2012. 
  27. ^ "KFF – KFIP – Winners 2013 – Medicine". King Faisal Foundation. 2013. 
  28. ^ Shell E (January 1, 2002). "On the Cutting Edge". The Hungry Gene: The Inside Story of the Obesity Industry. Atlantic Monthly Press.  
  29. ^ Shell E (2002). "Hunger". The Hungry Gene: The Inside Story of the Obesity Industry. Atlantic Monthly Press.  
  30. ^ Pool R (2001). Fat: fighting the obesity epidemic. New York: Oxford University Press.  
  31. ^ Kolata GB (2007). Rethinking thin: the new science of weight loss—and the myths and realities of dietin. New York: Farrar.  
  32. ^ Castracane VD, Henson MC (2006). "The Obese (ob/ob) Mouse and the Discovery of Leptin". In Castracane VD, Henson MC. Leptin. Endocrine Updates 25. pp. 1–9.  
  33. ^ Green ED, Maffei M, Braden VV, Proenca R, DeSilva U, Zhang Y, Chua SC, Leibel RL, Weissenbach J, Friedman JM (August 1995). "The human obese (OB) gene: RNA expression pattern and mapping on the physical, cytogenetic, and genetic maps of chromosome 7". Genome Res. 5 (1): 5–12.  
  34. ^ Montague CT, Farooqi IS, Whitehead JP, Soos MA, Rau H, Wareham NJ, Sewter CP, Digby JE, Mohammed SN, Hurst JA, Cheetham CH, Earley AR, Barnett AH, Prins JB, O'Rahilly S (1997). "Congenital leptin deficiency is associated with severe early-onset obesity in humans". Nature 387 (6636): 903–8.  
  35. ^ a b c d e Wabitsch M, Funcke JB, Lennerz B, Kuhnle-Krahl U, Lahr G, Debatin KM, Vatter P, Gierschik P, Moepps B, Fischer-Posovszky P. "Biologically Inactive Leptin and Early-Onset Extreme Obesity". N. Engl. J. Med. 372 (1): 48–54.  
  36. ^ a b Paracchini V, Pedotti P, Taioli E (2005). "Genetics of leptin and obesity: a HuGE review". Am. J. Epidemiol. 162 (2): 101–14.  
  37. ^ name="pmid16571841">Wang TN, Huang MC, Chang WT, Ko AM, Tsai EM, Liu CS, Lee CH, Ko YC. "G-2548A polymorphism of the leptin gene is correlated with extreme obesity in Taiwanese aborigines". Obesity (Silver Spring) 14 (2): 183–7.  
  38. ^ Zhang L, Lu M, Yuan L, Lai W, Wang Y (2014). "[Association of leptin gene-2548 G/A polymorphism with obesity: a meta-analysis]". Wei Sheng Yan Jiu (in Chinese) 43 (1): 128–32.  
  39. ^ name="pmid24564125">Zhang L, Lu M, Yuan L, Lai W, Wang Y (2014). "[Association of leptin gene-2548 G/A polymorphism with obesity: a meta-analysis]". Wei Sheng Yan Jiu (in Chinese) 43 (1): 128–32.  
  40. ^ Templeman LA, Reynolds GP, Arranz B, San L. (April 2005). "Polymorphisms of the 5-HT2C receptor and leptin genes are associated with antipsychotic drug-induced weight gain in Caucasian subjects with a first-episode psychosis.". Pharmacogenet Genomics. 15 (4): 195–200.  
  41. ^ Kang SG, Lee HJ, Park YM, Choi JE, Han C, Kim YK, Kim SH, Lee MS, Joe SH, Jung IK, Kim L (2008). "Possible association between the -2548A/G polymorphism of the leptin gene and olanzapine-induced weight gain". Prog. Neuropsychopharmacol. Biol. Psychiatry 32 (1): 160–3.  
  42. ^ Wu R, Zhao J, Shao P, Ou J, Chang M (2011). "Genetic predictors of antipsychotic-induced weight gain: a case-matched multi-gene study". Zhong Nan Da Xue Xue Bao Yi Xue Ban 36 (8): 720–3.  
  43. ^ Ribeiro R, Vasconcelos A, Costa S, Pinto D, Morais A, Oliveira J, Lobo F, Lopes C, Medeiros R (2004). "Overexpressing leptin genetic polymorphism (-2548 G/A) is associated with susceptibility to prostate cancer and risk of advanced disease". Prostate 59 (3): 268–74.  
  44. ^ Vaskú JA, Vaskú A, Dostálová Z, Bienert P (2006). "Association of leptin genetic polymorphism -2548 G/A with gestational diabetes mellitus". Genes Nutr 1 (2): 117–23.  
  45. ^ Ye XL, Lu CF (Oct 2013). "Association of polymorphisms in the leptin and leptin receptor genes with inflammatory mediators in patients with osteoporosis.". Endocrine. 44 (2): 481–8.  
  46. ^ a b c Margetic S, Gazzola C, Pegg GG, Hill RA (2002). "Leptin: a review of its peripheral actions and interactions". Int. J. Obes. Relat. Metab. Disord. 26 (11): 1407–1433.  
  47. ^ Bado A, Levasseur S, Attoub S, Kermorgant S, Laigneau JP, Bortoluzzi MN, Moizo L, Lehy T, Guerre-Millo M, Le Marchand-Brustel Y, Lewin MJ (August 1998). "The stomach is a source of leptin". Nature 394 (6695): 790–793.  
  48. ^ Sinha MK, Opentanova I, Ohannesian JP, Kolaczynski JW, Heiman ML, Hale J, Becker GW, Bowsher RR, Stephens TW, Caro JF (September 1996). "Evidence of free and bound leptin in human circulation. Studies in lean and obese subjects and during short-term fasting". J. Clin. Invest. 98 (6): 1277–82.  
  49. ^ Lönnqvist F, Arner P, Nordfors L, Schalling M (1995). "Overexpression of the obese (ob) gene in adipose tissue of human obese subjects". Nat. Med. 1 (9): 950–3.  
  50. ^ Madej T (1998). "Considerations in the use of lipid-based drug products". J Intraven Nurs 21 (6): 326.  
  51. ^ Sinha MK, Ohannesian JP, Heiman ML, Kriauciunas A, Stephens TW, Magosin S, Marco C, Caro JF (March 1996). "Nocturnal rise of leptin in lean, obese, and non-insulin-dependent diabetes mellitus subjects". J. Clin. Invest. 97 (5): 1344–7.  
  52. ^ Schoeller DA, Cella LK, Sinha MK, Caro JF (October 1997). "Entrainment of the diurnal rhythm of plasma leptin to meal timing". J. Clin. Invest. 100 (7): 1882–7.  
  53. ^ Chan JL, Heist K, DePaoli AM, Veldhuis JD, Mantzoros CS (May 2003). "The role of falling leptin levels in the neuroendocrine and metabolic adaptation to short-term starvation in healthy men". J. Clin. Invest. 111 (9): 1409–1421.  
  54. ^ Kolaczynski JW, Considine RV, Ohannesian J, Marco C, Opentanova I, Nyce MR, Myint M, Caro JF (November 1996). "Responses of leptin to short-term fasting and refeeding in humans: a link with ketogenesis but not ketones themselves". Diabetes 45 (11): 1511–5.  
  55. ^ Kolaczynski JW, Ohannesian JP, Considine RV, Marco CC, Caro JF (November 1996). "Response of leptin to short-term and prolonged overfeeding in humans". J. Clin. Endocrinol. Metab. 81 (11): 4162–5.  
  56. ^ Ahima RS, Prabakaran D, Mantzoros C, Qu D, Lowell B, Maratos-Flier E, Flier JS (July 1996). "Role of leptin in the neuroendocrine response to fasting". Nature 382 (6588): 250–2.  
  57. ^ Friedman JM (March 2009). "Leptin at 14 y of age: an ongoing story". Am. J. Clin. Nutr. 89 (3): 973S–979S.  
  58. ^ Zirlik S, Hauck T, Fuchs FS, Neurath MF, Konturek PC, Harsch IA (February 2011). "Leptin, Obestatin and Apelin levels in patients with obstructive sleep apnoea syndrome". Med. Sci. Monit. 17 (3): CR159–64.  
  59. ^ Harsch IA, Konturek PC, Koebnick C, Kuehnlein PP, Fuchs FS, Pour Schahin S, Wiest GH, Hahn EG, Lohmann T, Ficker JH (August 2003). "Leptin and ghrelin levels in patients with obstructive sleep apnoea: effect of CPAP treatment". Eur. Respir. J. 22 (2): 251–257.  
  60. ^ Copinschi G, Leproult R, Spiegel K (2014). "The important role of sleep in metabolism". Front Horm Res 42: 59–72.  
  61. ^ Knutson KL, Spiegel K, Penev P, Van Cauter E (June 2007). "The metabolic consequences of sleep deprivation". Sleep Med Rev 11 (3): 163–178.  
  62. ^ Otsuka R, Yatsuya H, Tamakoshi K, Matsushita K, Wada K, Toyoshima H (October 2006). "Perceived psychological stress and serum leptin concentrations in Japanese men". Obesity (Silver Spring) 14 (10): 1832–1838.  
  63. ^ Ahima RS, Flier JS (2000). "Leptin". Annu. Rev. Physiol. 62 (1): 413–437.  
  64. ^ de Salles BF, Simão R, Fleck SJ, Dias I, Kraemer-Aguiar LG, Bouskela E (July 2010). "Effects of resistance training on cytokines". Int J Sports Med 31 (7): 441–450.  
  65. ^ Hickey MS, Considine RV, Israel RG, Mahar TL, McCammon MR, Tyndall GL, Houmard JA, Caro JF (November 1996). "Leptin is related to body fat content in male distance runners". Am. J. Physiol. 271 (5 Pt 1): E938–40.  
  66. ^ Hickey MS, Houmard JA, Considine RV, Tyndall GL, Midgette JB, Gavigan KE, Weidner ML, McCammon MR, Israel RG, Caro JF (April 1997). "Gender-dependent effects of exercise training on serum leptin levels in humans". Am. J. Physiol. 272 (4 Pt 1): E562–6.  
  67. ^ Considine RV, Nyce MR, Kolaczynski JW, Zhang PL, Ohannesian JP, Moore JH, Fox JW, Caro JF (May 1997). "Dexamethasone stimulates leptin release from human adipocytes: unexpected inhibition by insulin". J. Cell. Biochem. 65 (2): 254–8.  
  68. ^ Kolaczynski JW, Nyce MR, Considine RV, Boden G, Nolan JJ, Henry R, Mudaliar SR, Olefsky J, Caro JF (May 1996). "Acute and chronic effects of insulin on leptin production in humans: Studies in vivo and in vitro". Diabetes 45 (5): 699–701.  
  69. ^ a b Caro JF, Sinha MK, Kolaczynski JW, Zhang PL, Considine RV (November 1996). "Leptin: the tale of an obesity gene". Diabetes 45 (11): 1455–62.  
  70. ^ Mantzoros CS (1999). "The role of leptin in human obesity and disease: a review of current evidence". Ann. Intern. Med. 130 (8): 671–80.  
  71. ^ a b Elmquist JK, Elias CF, Saper CB (Feb 1999). "From lesions to leptin: hypothalamic control of food intake and body weight". Neuron 22 (2): 221–32.  
  72. ^ Elias CF, Aschkenasi C, Lee C, Kelly J, Ahima RS, Bjorbaek C, Flier JS, Saper CB, Elmquist JK (Aug 1999). "Leptin differentially regulates NPY and POMC neurons projecting to the lateral hypothalamic area". Neuron 23 (4): 775–86.  
  73. ^ Fekete C, Légrádi G, Mihály E, Huang QH, Tatro JB, Rand WM, Emerson CH, Lechan RM (Feb 2000). "alpha-Melanocyte-stimulating hormone is contained in nerve terminals innervating thyrotropin-releasing hormone-synthesizing neurons in the hypothalamic paraventricular nucleus and prevents fasting-induced suppression of prothyrotropin-releasing hormone gene expression". The Journal of Neuroscience 20 (4): 1550–1558.  
  74. ^ Dubuc GR, Phinney SD, Stern JS, Havel PJ (1998). "Changes of serum leptin and endocrine and metabolic parameters after 7 days of energy restriction in men and women". Metab. Clin. Exp. 47 (4): 429–34.  
  75. ^ Pratley RE, Nicolson M, Bogardus C, Ravussin E (1997). "Plasma leptin responses to fasting in Pima Indians". Am. J. Physiol. 273 (3 Pt 1): E644–9.  
  76. ^ Weigle DS, Duell PB, Connor WE, Steiner RA, Soules MR, Kuijper JL (February 1997). "Effect of fasting, refeeding, and dietary fat restriction on plasma leptin levels". J. Clin. Endocrinol. Metab. 82 (2): 561–5.  
  77. ^ Wadden TA, Considine RV, Foster GD, Anderson DA, Sarwer DB, Caro JS (January 1998). "Short- and long-term changes in serum leptin dieting obese women: effects of caloric restriction and weight loss". J. Clin. Endocrinol. Metab. 83 (1): 214–8.  
  78. ^ Chin-Chance C, Polonsky KS, Schoeller DA (2000). "Twenty-four-hour leptin levels respond to cumulative short-term energy imbalance and predict subsequent intake". J. Clin. Endocrinol. Metab. 85 (8): 2685–2691.  
  79. ^ Keim NL, Stern JS, Havel PJ (1998). "Relation between circulating leptin concentrations and appetite during a prolonged, moderate energy deficit in women". Am. J. Clin. Nutr. 68 (4): 794–801.  
  80. ^ Mars M, de Graaf C, de Groot CP, van Rossum CT, Kok FJ (2006). "Fasting leptin and appetite responses induced by a 4-day 65%-energy-restricted diet". International journal of obesity (Lond) 30 (1): 122–128.  
  81. ^ Williams KW, Scott MM, Elmquist JK (March 2009). "From observation to experimentation: leptin action in the mediobasal hypothalamus". Am. J. Clin. Nutr. 89 (3): 985S–990S.  
  82. ^ Baicy K, London ED, Monterosso J, Wong ML, Delibasi T, Sharma A, Licinio J (November 2007). "Leptin replacement alters brain response to food cues in genetically leptin-deficient adults". Proc. Natl. Acad. Sci. U.S.A. 104 (46): 18276–9.  
  83. ^ Wang MY, Zhou YT, Newgard CB, Unger RH (August 1996). "A novel leptin receptor isoform in rat". FEBS Lett. 392 (2): 87–90.  
  84. ^ Malendowicz W, Rucinski M, Macchi C, Spinazzi R, Ziolkowska A, Nussdorfer GG, Kwias Z (October 2006). "Leptin and leptin receptors in the prostate and seminal vesicles of the adult rat". Int. J. Mol. Med. 18 (4): 615–8.  
  85. ^ "LepRb antibody (commercial site)". 
  86. ^ Lynn RB, Cao GY, Considine RV, Hyde TM, Caro JF (February 1996). "Autoradiographic localization of leptin binding in the choroid plexus of ob/ob and db/db mice". Biochem. Biophys. Res. Commun. 219 (3): 884–9.  
  87. ^ Di Marzo V (2008). "The endocannabinoid system in obesity and type 2 diabetes". Diabetologia 51 (8): 1356–67.  
  88. ^ Kus I, Sarsilmaz M, Colakoglu N, Kukne A, Ozen OA, Yilmaz B, Kelestimur H (2004). "Pinealectomy increases and exogenous melatonin decreases leptin production in rat anterior pituitary cells: an immunohistochemical study". Physiol Res 53 (4): 403–8.  
  89. ^ Alonso-Vale MI, Andreotti S, Peres SB, Anhê GF, das Neves Borges-Silva C, Neto JC, Lima FB (April 2005). "Melatonin enhances leptin expression by rat adipocytes in the presence of insulin". Am. J. Physiol. Endocrinol. Metab. 288 (4): E805–E812.  
  90. ^ Copinschi G (2005). "Metabolic and endocrine effects of sleep deprivation". Essential psychopharmacology 6 (6): 341–7.  
  91. ^ Wang MY, Chen L, Clark GO, Lee Y, Stevens RD, Ilkayeva OR, Wenner BR, Bain JR, Charron MJ, Newgard CB, Unger RH (March 2010). "Leptin therapy in insulin-deficient type I diabetes". Proc. Natl. Acad. Sci. U.S.A. 107 (11): 4813–4819.  
  92. ^ Taleb S, Herbin O, Ait-Oufella H, Verreth W, Gourdy P, Barateau V, Merval R, Esposito B, Clément K, Holvoet P, Tedgui A, Mallat Z (2007). "Defective leptin/leptin receptor signaling improves regulatory T cell immune response and protects mice from atherosclerosis". Arterioscler Thromb Vasc Biol. 27 (12): 2691–2698.  
  93. ^ Zhang W, Telemaque S, Augustyniak RA, Anderson P, Thomas GD, An J, Wang Z, Newgard CB, Victor RG (2010). "Adenovirus-mediated leptin expression normalises hypertension associated with diet-induced obesity". J Neuroendocrinol. 22 (3): 175–180.  
  94. ^ Knight WD, Seth R, Boron J, Overton JM (2009). "Short-term physiological hyperleptinemia decreases arterial blood pressure". Regul Pept. 154 (1–3): 60–68.  
  95. ^ Ciriello J, Moreau JM (November 2012). "Systemic administration of leptin potentiates the response of neurons in the nucleus of the solitary tract to chemoreceptor activation in the rat". J. Neuroscience 229: 88–99.  
  96. ^ Torday JS, Rehan VK (October 2006). "Up-regulation of fetal rat lung parathyroid hormone-related protein gene regulatory network down-regulates the Sonic Hedgehog/Wnt/beta-catenin gene regulatory network". Pediatr. Res. 60 (4): 382–8.  
  97. ^ Anifandis G, Koutselini E, Louridas K, Liakopoulos V, Leivaditis K, Mantzavinos T, Sioutopoulou D, Vamvakopoulos N (April 2005). "Estradiol and leptin as conditional prognostic IVF markers". Reproduction 129 (4): 531–534.  
  98. ^ Comninos AN, Jayasena CN, Dhillo WS (2014). "The relationship between gut and adipose hormones, and reproduction". Hum. Reprod. Update 20 (2): 153–74.  
  99. ^ Zhao J, Townsend KL, Schulz LC, Kunz TH, Li C, Widmaier EP (2004). "Leptin receptor expression increases in placenta, but not hypothalamus, during gestation in Mus musculus and Myotis lucifugus". Placenta 25 (8–9): 712–722.  
  100. ^ Moynihan AT, Hehir MP, Glavey SV, Smith TJ, Morrison JJ (2006). "Inhibitory effect of leptin on human uterine contractility in vitro". Am. J. Obstet. Gynecol. 195 (2): 504–509.  
  101. ^ Aka N, Atalay S, Sayharman S, Kiliç D, Köse G, Küçüközkan T (2006). "Leptin and leptin receptor levels in pregnant women with hyperemesis gravidarum". The Australian & New Zealand journal of obstetrics & gynaecology 46 (4): 274–277.  
  102. ^ Cervero A, Domínguez F, Horcajadas JA, Quiñonero A, Pellicer A, Simón C (2006). "The role of the leptin in reproduction". Current Opinion in Obstetrics and Gynecology 18 (3): 297–303.  
  103. ^ Iwaniec UT, Boghossian S, Lapke PD, Turner RT, Kalra SP (2007). "Central leptin gene therapy corrects skeletal abnormalities in leptin-deficient ob/ob mice". Peptides 28 (5): 1012–1019.  
  104. ^ Casabiell X, Piñeiro V, Tomé MA, Peinó R, Diéguez C, Casanueva FF (1997). "Presence of leptin in colostrum and/or breast milk from lactating mothers: a potential role in the regulation of neonatal food intake". J. Clin. Endocrinol. Metab. 82 (12): 4270–3.  
  105. ^ Sanchez-Garrido MA, Tena-Sempere M (2013). "Metabolic control of puberty: roles of leptin and kisspeptins". Horm Behav 64 (2): 187–94.  
  106. ^ Matkovic V, Ilich JZ, Skugor M, Badenhop NE, Goel P, Clairmont A, Klisovic D, Nahhas RW, Landoll JD (October 1997). "Leptin is inversely related to age at menarche in human females". J. Clin. Endocrinol. Metab. 82 (10): 3239–45.  
  107. ^ Ducy P, Amling M, Takeda S, Priemel M, Schilling AF, Beil FT, Shen J, Vinson C, Rueger JM, Karsenty G (January 2000). "Leptin inhibits bone formation through a hypothalamic relay: a central control of bone mass". Cell 100 (2): 197–207.  
  108. ^ a b Hamrick MW, Ferrari SL (July 2008). "Leptin and the sympathetic connection of fat to bone". Osteoporos Int 19 (7): 905–912.  
  109. ^ a b Allison SJ, Herzog H (2006). "NPY and bone". EXS (95): 171–82.  
  110. ^ Gordeladze JO, Reseland JE (March 2003). "A unified model for the action of leptin on bone turnover". J. Cell. Biochem. 88 (4): 706–712.  
  111. ^ Takeda S, Elefteriou F, Levasseur R, Liu X, Zhao L, Parker KL, Armstrong D, Ducy P, Karsenty G (November 2002). "Leptin regulates bone formation via the sympathetic nervous system". Cell 111 (3): 305–317.  
  112. ^ Martin A, David V, Malaval L, Lafage-Proust MH, Vico L, Thomas T (2007). "Opposite effects of leptin on bone metabolism: a dose-dependent balance related to energy intake and insulin-like growth factor-I pathway". Endocrinology 148 (7): 3419–25.  
  113. ^ Rőszer T, Józsa T, Kiss-Tóth ED, De Clerck N, Balogh L (April 2014). "Leptin receptor deficient diabetic (db/db) mice are compromised in postnatal bone regeneration.". Cell and Tissue Research 356 (1): 195–206.  
  114. ^ Farr SA, Banks WA, Morley JE (June 2006). "Effects of leptin on memory processing". Peptides 27 (6): 1420–5.  
  115. ^ Casanueva FF, Dieguez C, Popovic V, Peino R, Considine RV, Caro JF (April 1997). "Serum immunoreactive leptin concentrations in patients with anorexia nervosa before and after partial weight recovery". Biochem. Mol. Med. 60 (2): 116–20.  
  116. ^ Lieb W, Beiser AS, Vasan RS, Tan ZS, Au R, Harris TB, Roubenoff R, Auerbach S, DeCarli C, Wolf PA, Seshadri S (December 2009). "Association of plasma leptin levels with incident Alzheimer disease and MRI measures of brain aging". JAMA 302 (23): 2565–72.  
  117. ^ Greco SJ, Bryan KJ, Sarkar S, Zhu X, Smith MA, Ashford JW, Johnston JM, Tezapsidis N, Casadesus G (2010). "Leptin reduces pathology and improves memory in a transgenic mouse model of Alzheimer's disease". J. Alzheimers Dis. 19 (4): 1155–67.  
  118. ^ Doherty GH, Beccano-Kelly D, Yan SD, Gunn-Moore FJ, Harvey J (January 2013). "Leptin prevents hippocampal synaptic disruption and neuronal cell death induced by amyloid β". Neurobiol. Aging 34 (1): 226–37.  
  119. ^ Greco SJ, Sarkar S, Johnston JM, Tezapsidis N (February 2009). "Leptin regulates tau phosphorylation and amyloid through AMPK in neuronal cells". Biochem. Biophys. Res. Commun. 380 (1): 98–104.  
  120. ^ Lord GM, Matarese G, Howard JK, Baker RJ, Bloom SR, Lechler RI (August 1998). "Leptin modulates the T-cell immune response and reverses starvation-induced immunosuppression". Nature 394 (6696): 897–901.  
  121. ^ a b Fantuzzi G, Faggioni R (October 2000). "Leptin in the regulation of immunity, inflammation, and hematopoiesis". J. Leukoc. Biol. 68 (4): 437–46.  
  122. ^ Caldefie-Chezet F, Poulin A, Tridon A, Sion B, Vasson MP (March 2001). "Leptin: a potential regulator of polymorphonuclear neutrophil bactericidal action?". J. Leukoc. Biol. 69 (3): 414–8.  
  123. ^ Madej T, Boguski MS, Bryant SH (October 1995). "Threading analysis suggests that the obese gene product may be a helical cytokine". FEBS Lett. 373 (1): 13–18.  
  124. ^ Heiman ML, Ahima RS, Craft LS, Schoner B, Stephens TW, Flier JS (September 1997). "Leptin inhibition of the hypothalamic-pituitary-adrenal axis in response to stress". Endocrinology 138 (9): 3859–3863.  
  125. ^ Mabuchi T, Yatsuya H, Tamakoshi K, Otsuka R, Nagasawa N, Zhang H, Murata C, Wada K, Ishikawa M, Hori Y, Kondo T, Hashimoto S, Toyoshima H (2005). "Association between serum leptin concentration and white blood cell count in middle-aged Japanese men and women". Diabetes Metab. Res. Rev. 21 (5): 441–447.  
  126. ^ Hamilton BS, Paglia D, Kwan AY, Deitel M (September 1995). "Increased obese mRNA expression in omental fat cells from massively obese humans". Nat. Med. 1 (9): 953–956.  
  127. ^ Perrier S, Caldefie-Chézet F, Vasson MP (January 2009). "IL-1 family in breast cancer: potential interplay with leptin and other adipocytokines". FEBS Lett. 583 (2): 259–65.  
  128. ^ Wabitsch M, Jensen PB, Blum WF, Christoffersen CT, Englaro P, Heinze E, Rascher W, Teller W, Tornqvist H, Hauner H (October 1996). "Insulin and cortisol promote leptin production in cultured human fat cells". Diabetes 45 (10): 1435–1438.  
  129. ^ LaPensee CR, Hugo ER, Ben-Jonathan N (November 2008). "Insulin stimulates interleukin-6 expression and release in LS14 human adipocytes through multiple signaling pathways". Endocrinology 149 (11): 5415–5422.  
  130. ^ Worm D, Vinten J, Vaag A, Henriksen JE, Beck-Nielsen H (September 2000). "The nicotinic acid analogue acipimox increases plasma leptin and decreases free fatty acids in type 2 diabetic patients". Eur. J. Endocrinol. 143 (3): 389–395.  
  131. ^ a b Myers MG, Cowley MA, Münzberg H (2008). "Mechanisms of leptin action and leptin resistance". Annu. Rev. Physiol. 70 (1): 537–556.  
  132. ^ a b Veyrat-Durebex C, Poher AL, Caillon A, Somm E, Vallet P, Charnay Y, Rohner-Jeanrenaud F (2013). "Improved leptin sensitivity as a potential candidate responsible for the spontaneous food restriction of the Lou/C rat". PLoS ONE 8 (9): e73452.  
  133. ^ a b Caro JF, Kolaczynski JW, Nyce MR, Ohannesian JP, Opentanova I, Goldman WH, Lynn RB, Zhang PL, Sinha MK, Considine RV (20 July 1996). "Decreased cerebrospinal-fluid/serum leptin ratio in obesity: a possible mechanism for leptin resistance". Lancet 348 (9021): 159–61.  
  134. ^ Considine RV, Considine EL, Williams CJ, Hyde TM, Caro JF (1996). "The hypothalamic leptin receptor in humans: identification of incidental sequence polymorphisms and absence of the db/db mouse and fa/fa rat mutations". Diabetes 45 (7): 992–4.  
  135. ^ Considine RV, Caro JF (November 1997). "Leptin and the regulation of body weight". Int. J. Biochem. Cell Biol. 29 (11): 1255–72.  
  136. ^ a b Oswal A, Yeo G (February 2010). "Leptin and the control of body weight: a review of its diverse central targets, signaling mechanisms, and role in the pathogenesis of obesity". Obesity (Silver Spring) 18 (2): 221–9.  
  137. ^ Shapiro A, Mu W, Roncal C, Cheng KY, Johnson RJ, Scarpace PJ (November 2008). "Fructose-induced leptin resistance exacerbates weight gain in response to subsequent high-fat feeding". Am. J. Physiol. Regul. Integr. Comp. Physiol. 295 (5): R1370–R1375.  
  138. ^ Vasselli JR (November 2008). "Fructose-induced leptin resistance: discovery of an unsuspected form of the phenomenon and its significance. Focus on "Fructose-induced leptin resistance exacerbates weight gain in response to subsequent high-fat feeding," by Shapiro et al". Am. J. Physiol. Regul. Integr. Comp. Physiol. 295 (5): R1365–R1369.  
  139. ^ Harris RB, Apolzan JW (Jun 2012). "Changes in glucose tolerance and leptin responsiveness of rats offered a choice of lard, sucrose, and chow.". Am J Physiol Regul Integr Comp Physiol. 302 (11): R1327–39.  
  140. ^ Roth JD, Roland BL, Cole RL, Trevaskis JL, Weyer C, Koda JE, Anderson CM, Parkes DG, Baron AD (May 2008). "Leptin responsiveness restored by amylin agonism in diet-induced obesity: evidence from nonclinical and clinical studies". Proc. Natl. Acad. Sci. U.S.A. 105 (20): 7257–7262.  
  141. ^ Banks WA, Farr SA, Morley JE (June 2006). "The effects of high fat diets on the blood-brain barrier transport of leptin: failure or adaptation?". Physiol. Behav. 88 (3): 244–8.  
  142. ^ Wang J, Obici S, Morgan K, Barzilai N, Feng Z, Rossetti L (December 2001). "Overfeeding rapidly induces leptin and insulin resistance". Diabetes 50 (12): 2786–2791.  
  143. ^ Enriori PJ, Evans AE, Sinnayah P, Jobst EE, Tonelli-Lemos L, Billes SK, Glavas MM, Grayson BE, Perello M, Nillni EA, Grove KL, Cowley MA (March 2007). "Diet-induced obesity causes severe but reversible leptin resistance in arcuate melanocortin neurons". Cell Metab. 5 (3): 181–194.  
  144. ^ Obici S, Rossetti L (December 2003). "Minireview: nutrient sensing and the regulation of insulin action and energy balance". Endocrinology 144 (12): 5172–8.  
  145. ^ a b Ahima RS (July 2008). "Revisiting leptin's role in obesity and weight loss". J. Clin. Invest. 118 (7): 2380–3.  
  146. ^ Sinha G (2014). "Leptin therapy gains FDA approval". Nat. Biotechnol. 32 (4): 300–2.  
  147. ^ Chou K, Perry CM (2013). "Metreleptin: first global approval". Drugs 73 (9): 989–997.  
  148. ^ "FDA approves Myalept to treat rare metabolic disease". FDA. Feb 25, 2014. Retrieved 30 April 2014. 

References

Leptin and Ghrelin on the metabolism control

Some Schemes

See also

  1. ^ This term can be misleading, bearing in mind that other hormones such as ghrelin operate in a faster-time scale. Leptin controls the satiety indirectly by saying that we do or not have enough energy on board. It would be better defined as "the hormone of energy expenditure".

Notes

An analog of human leptin metreleptin (trade name Myalept) was first approved in Japan in 2013, and in the United States (U.S.) in February 2014. In the U.S. it is indicated as a treatment for complications of leptin deficiency, and for the diabetes and hypertriglyceridemia associated with congenital or acquired generalized lipodystrophy.[147][148]

Analog metreleptin

Leptin was approved in the United States in 2014 for use in congenital leptin deficiency and generalized lipodystrophy.[146]

Leptin

Therapeutic use

A decline in levels of circulating leptin also changes brain activity in areas involved in the regulatory, emotional, and cognitive control of appetite that are reversed by administration of leptin.[145]

Dieters who lose weight, particularly those with an overabundance of fat cells, experience a drop in levels of circulating leptin. This drop causes reversible decreases in thyroid activity, sympathetic tone, and energy expenditure in skeletal muscle, and increases in muscle efficiency and parasympathetic tone. The result is that a person who has lost weight below their natural body fat set-point has a lower basal metabolic rate than an individual at the same weight who is of that natural weight; these changes are leptin-mediated, homeostatic responses meant to reduce energy expenditure and promote weight regain as a result of fat cells being shrunken below normal size. Many of these changes are reversed by peripheral administration of recombinant leptin to restore pre-diet levels.[145]

Response to weight loss

It has been suggested that the main role of leptin is to act as a starvation signal when levels are low, to help maintain fat stores for survival during times of starvation, rather than a satiety signal to prevent overeating. Leptin levels signal when an animal has enough stored energy to spend it in pursuits besides acquiring food.[136][141] This would mean that leptin resistance in obese people is a normal part of mammalian physiology and possibly, could confer a survival advantage.[131] Leptin resistance (in combination with insulin resistance and weight gain) is seen in rats after they are given unlimited access to palatable, energy-dense foods.[142] This effect is reversed when the animals are put back on a low-energy diet.[143] This also may have an evolutionary advantage: allowing energy to be stored efficiently when food is plentiful would be advantageous in populations where food frequently may be scarce.[144]

Leptin is known to interact with amylin, a hormone involved in gastric emptying and creating a feeling of fullness. When both leptin and amylin were given to obese, leptin-resistant rats, sustained weight loss was seen. Due to its apparent ability to reverse leptin reisistance, amylin has been suggested as possible therapy for obesity.[140]

The consumption of a high fructose diet from birth has been associated with a reduction in leptin levels and reduced expression of leptin receptor mRNA in rats. Long-term consumption of fructose in rats has been shown to increase levels of triglycerides and trigger leptin and insulin resistance,[137][138] however, another study found that leptin resistance only developed in the presence of both high fructose and high fat levels in the diet. A third study found that high fructose levels reversed leptin resistance in rats given a high fat diet. The contradictory results mean that it is uncertain whether leptin resistance is caused by high levels of carbohydrates or fats, or if an increase of both, is needed.[139]

When leptin binds with the leptin receptor, it activates a number of pathways. Leptin resistance may be caused by defects in one or more part of this process, particularly the JAK/STAT pathway. Mice with a mutation in the leptin receptor gene that prevents the activation of STAT3 are obese and exhibit hyperphagia. The PI3K pathway may also be involved in leptin resistance, as has been demonstrated in mice by artificial blocking of PI3K signalling. The PI3K pathway also is activated by the insulin receptor and is therefore an important area where leptin and insulin act together as part of energy homeostasis. The insulin-pI3K pathway can cause POMC neurons to become insensitive to leptin through hyperpolarization.[136]

Studies on leptin cerebrospinal fluid (CSF) levels provide evidence for the reduction in leptin crossing the BBB and reaching obesity-relevant targets, such as the hypothalamus, in obese people[132] In humans it has been observed that the ratio of leptin in the CSF compared to the blood is lower in obese people than in people of a normal weight.[133] The reason for this may be high levels of triglycerides affecting the transport of leptin across the BBB or due to the leptin transporter becoming saturated.[132] Although deficits in the transfer of leptin from the plasma to the CSF is seen in obese people, they are still found to have 30% more leptin in their CSF than lean individuals.[133] These higher CSF levels fail to prevent their obesity. Since the amount and quality of leptin receptors in the hypothalamus appears to be normal in the majority of obese humans (as judged from leptin-mRNA studies),[134] it is likely that the leptin resistance in these individuals is due to a post leptin-receptor deficit, similar to the post-insulin receptor defect seen in type 2 diabetes.[135]

Although leptin reduces appetite as a circulating signal, obese individuals generally exhibit a higher circulating concentration of leptin than normal weight individuals due to their higher percentage body fat.[9] These people show resistance to leptin, similar to resistance of insulin in type 2 diabetes, with the elevated levels failing to control hunger and modulate their weight. A number of explanations have been proposed to explain this. An important contributor to leptin resistance is changes to leptin receptor signalling, particularly in the arcuate nucleus, however, deficiency of, or major changes to, the leptin receptor itself are not thought to be a major cause. Other explanations suggested include changes to the way leptin crosses the blood brain barrier or alterations occurring during development.[131]

Obesity

Role in obesity and weight loss

[69] Such findings appear to demonstrate high caloric loads in excess of storage rate capacities of fat cells lead to stress responses that induce an increase in leptin, which then operates as an adipose-derived inflammation stopgap signaling for the cessation of food intake so as to prevent adipose-derived inflammation from reaching elevated levels. This response may then protect against the harmful process of ectopic fat storage, which perhaps explains the connection between chronically elevated leptin levels and ectopic fat storage in obese individuals.[130], concurrent hypocaloric dieting and weight loss notwithstanding.lipolysis is administered to prevent acipimox Furthermore, plasma leptin concentrations have been observed to gradually increase when [129] in a time- and dose-dependent manner.)preadipocytes (This insulin-leptin relationship is notably similar to insulin's effect on the increase of IL-6 gene expression and secretion from [128]

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.