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Ventromedial nucleus of the hypothalamus

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Title: Ventromedial nucleus of the hypothalamus  
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Ventromedial nucleus of the hypothalamus

Ventromedial nucleus of the hypothalamus
Ventromedial nucleus is 'VM', at center, in green.
Details
Latin nucleus ventromedialis hypothalami
Part of Hypothalamus
Basilar
Identifiers
MeSH A08.186.211.730.385.357.352.953
NeuroNames hier-381
NeuroLex ID Ventromedial nucleus of hypothalamus
Dorlands
/Elsevier
n_11/12584102
Anatomical terms of neuroanatomy

The ventromedial nucleus of the hypothalamus (VMN, also sometimes referred to as the ventromedial hypothalamus, VMH) is a nucleus of the hypothalamus. "The ventromedial hypothalamus (VMH) is a distinct morphological nucleus involved in feeding, fear, thermoregulation, and sexual activity."[1] This nuclear region is involved with the recognition of the feeling of fullness.

Contents

  • Structure 1
  • Function 2
  • References 3
  • Further References 4
  • External links 5

Structure

It has four subdivisions:

  • anterior (VMHa)
  • dorsomedial (VMHdm)
  • ventrolateral (VMHvl)
  • central (VMHc).

These subdivisions differ anatomically, neurochemically, and behaviorally.

Function

The ventromedial nucleus (VMN) is most commonly associated with satiety. Early studies showed that VMN lesions caused over-eating and obesity in rats. However, the interpretation of these experiments was summarily discredited when Gold's research demonstrated that precision lesioning of the VMN did not result in hyperphagia.[2] Nevertheless, numerous studies have shown that the immediacy of hyperphagia and obesity syndrome are a consequence of VMN lesions or procaine injections, and point to the VMN's role in satiety.[3][4][5][6][7][8][9] A major review of the subject in 2006 concluded that, "anatomical studies done both before and after Gold's study did not replicate his results with lesions, and in nearly every published direct comparison of VMH lesions vs. PVN or VNAB lesions, the group with VMH lesions ate substantially more food and gained twice as much weight."[10] This strongly substantiates the classification of VMN as the primary satiety center in the hypothalamus.

It has also been found that lesions to the VMH in rats caused increased plasma insulin levels. Rats with a VMH lesion compared to normal rats overproduce a circulating satiety factor, to which the control rats can respond and rats with a VMH lesion cannot respond. A lesion to the VMH makes rats overproduce leptin, which they cannot respond to causing them to over eat, leading to obesity.[11]

Two researchers, Heterington and Ranson, looked at series of twenty-one animals of various degrees of adiposity, with respect to growth appearance, fat distribution, general physical condition, and the correlation between the level of adiposity attained and the correlation of the hypothalamic lesion. Lesions in the hypothalamic area, particularly the region of the ventromedial hypothalamus interrupts a large number of the descending fibers from the hypothalamic cell groups that were found to contribute to obesity in rats.[12]

Taylor and Jamshi found that there seems to be a higher concentration of cannabinoid receptor mRNA within the VMH in comparison to other nuclei within the hypothalamus. The cannabinoid ingestion has been linked to rewarding processes, and also with the release of dopamine in the brain.[13]

VMH is also important in mammal play behaviour. Lesions to VMH along with the hippocampus, amygdala, the cerebellum, and the lateral hypothalamus are all linked to reduced play [14]

The VMHdm has a role in the male vocalizations and scent marking behaviors.[15][16][17]

The VMHvl plays a role in sexual behaviors in females (lordosis), thus stimulating their sexual arousal.[18][19][20][21]

Bilateral FOS expression in the VMH after repeated seizures is associated with alteration in the severity of flurothyl induced seizures in C57BL/6J mice that are not present in DBA/2J mice. [22]

References

  1. ^ Kurrasch, D., & Cheung, C. (2007). The neonatal ventromedial hypothalamus transcriptome reveals novel markers with spatially distinct patterning" The Journal of Neuroscience 27(50), Retrieved from http://www.jneurosci.org/content/27/50/13624.full.pdf
  2. ^
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  11. ^
  12. ^
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  14. ^
  15. ^ Yahr and Green, 1992
  16. ^ Flanagan-Cato et al. 2001
  17. ^ Harding and McGinnis, 2005
  18. ^ Kow and Pfaff, 1998
  19. ^ Christensen et al., 1977
  20. ^ Pfaff and Sakuma, 1979
  21. ^ Matsumoto and Yamanouchi, 2000
  22. ^ Kadiyala et al.

Further References

  • Dugger, et al. (2007). Androgen receptors are required for full masculinization of the ventromedial hypothalamus (VMH) in rats.
  • Storlien, L., & Albert, D. (1972). The effect of vmh lesions, lateral cuts and anterior cuts on food intake, activity level, food motivation, and reactivity to taste . Physiology & Behavior, 9(2), 191–192. Retrieved from http://www.sciencedirect.com/science/article/pii/003193847290234X
  • Carlson, N. (2010). Physiology of behavior. (10 ed., pp. 355–357). Boston: Allyn and Bacon.

External links

  • Diagram of Ventromedial motor tract at lemoyne.edu
  • New Scientist: Seat of female libido revealed (June 26, 2006)
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