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Ventromedial nucleus

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Brain: Ventromedial nucleus
HypothalamicNuclei
Ventromedial nucleus is 'VM', at center, in green.
[[Image:|250px|center|]]
Latin nucleus ventromedialis hypothalami
Gray's subject #
Part of Hypothalamus
Components
Artery Basilar
Vein
BrainInfo/UW hier-381
MeSH A08.186.211.730.385.357.352.953

The ventromedial nucleus (sometimes referred to as the ventromedial hypothalamus or 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]

DivisionEdit

It has four subdivisions:

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

These subdivisions differ anatomically, neurochemically, and behaviorally.

Lateral Hypothalamus: This region of the brain is associated with hunger recognition.[2][3]

Ventromedial Hypothalamus: This nuclear region is involved with the recognition of the feeling of fullness.

FunctionEdit

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.[4] 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.[5][6][7][8][9][10][11] 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."[12] 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.[13]

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.[14]

Taylor and Jamshi found that there seems to be a higher concentration of cannabinoid receptor mRNA within the ventromedial hypothalamus 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.[15]

VMH is also important in animal play behaviour in mammals. Lesions to VMH along with the hippocampus, amygdala, the cerebellum and the lateral hypothalamus will all reduce play behaviour.

In animals the VMHdm has a role in the male animal vocalizations and scent marking behaviors.[16][17][18]

The VMHvl plays a role in sexual behaviors in females (lordosis), thus stimulating their sexual arousal.[19][20][21][22]


See alsoEdit

ReferencesEdit

  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. The role of the hypothalamus in hunger.
  3. Carlson, N. (2010). Physiology of behavior. (10 ed., pp. 355-357). Boston: Allyn and Bacon.
  4. Gold, R.M. (1973). Hypothalamic Obesity: The myth of the ventromedial nucleus. Science 182: 488–490.
  5. Balagura, S., Devenport, L.D. (1970). Feeding patterns of normal and ventromedial hypothalamic lesioned male and female rats. J. Comp Physiol Psychol 71: 357–364.
  6. Becker, E.E., Kissileff, H.R. (1974). Inhibitory controls of feeding by the ventromedial hypothalamus. Am J. Physiol 226: 383–396.
  7. Berthoud, H.R., Jeanrenaud, B. (1979). Changes in insulinemia, glycemia and feeding behavior induced by VMH-procainization in the rat. Brain Res 174: 184–187.
  8. Brooks, C.M., Lockwood, R.A., Wiggins, M.L. (1946). A study of the effects of hypothalamic lesions on the eating habits of the albino rat. Am J Physiol 147: 735–741.
  9. Epstein, A.N. (1960). Reciprocal changes in feeding behavior produced by intrahypothalamic chemical injections. Am J Physiol 199: 969–974.
  10. Larkin, R.P. (1975). Effect of ventromedial hypothalamic procaine injections on feeding, lever pressing, and other behavior in the rat. J Comp Physiol Psychol 89: 1100–1108.
  11. Maes, H. (1980). Time course of feeding induced by pentobarbital-injections into the rat's VMH. Physiol Behav 24: 1107–1114.
  12. King, Bruce M. (February 2006). The rise, fall and resurrection of the ventromedial hypothalamus in the regulation of feeding behavior and body weight. J Physiol Behav 87 (2): 221–244.
  13. {{ SATOH, N., & OGAWA, Y. (1997). Pathophysiological significance of the obese gene product, leptin, in ventromedial hypothalamus (vmh)- lesioned rats: Evidence for loss of its satiety effect in vmh-lesioned rats*. Department of Medicine and Clinical Science, 138(3), 847-150. Retrieved from http://endo.endojournals.org/content/138/3/947.full.pdf html}}
  14. {{ Hetherinton , A., & Ranson, S. (n.d.). The relation of various hypothalamic lesions to adiposity in the rat. Institute of Neurology, Northwestern University Medical School, 477-481. Retrieved from https://wiki.brown.edu/confluence/download/attachments/74844947/rathypothalamus.pdf }}
  15. {{ Jamshidi, N., & Taylor, D. (2001). Anandamide administration into the ventromedial hypothalamus stimulates appetite in rats. Institute of Neurology, Northwestern University Medical School, 134, 1151- 1154. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1573067/pdf/134-0704379a.pdf}}
  16. Yahr and Green, 1992
  17. Flanagan-Cato et al. 2001
  18. Harding and McGinnis, 2005
  19. Kow and Pfaff, 1998
  20. Christensen et al., 1977
  21. Pfaff and Sakuma, 1979
  22. Matsumoto and Yamanouchi, 2000
  • Dugger, et al. (2007). Androgen receptors are required for full masculinization of the ventromedial hypothalamus (VMH) in rats.

[1] [2]


External linksEdit


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