Androgen receptors are required for full masculinization of the ventromedial hypothalamus (VMH) in rats

Brittany Dugger, John A. Morris, Cynthia L. Jordan, S. Marc Breedlove

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

The ventromedial hypothalamus (VMH) is one of several sexually dimorphic nuclei that regulate mating behavior, and is rich in steroid hormone receptors and aromatase activity. We looked at the contribution of the androgen receptor (AR) to the volume of the VMH in rats by measuring each of the four subdivisions of the VMH in 90 day old male, female, and XY male rats carrying a mutant AR allele (tfm), which renders animals largely unresponsive to androgens. Confirming published reports, total VMH volume was greater in wild-type males than in females (P < 0.01). The mean total volume of the VMH in TFM males was intermediate, but not significantly different from either females or males (Ps > 0.10). The sex difference in VMH volume was primarily accounted for by the ventrolateral subdivision (VMHvl), which in both females and TFM males was significantly smaller than in wild-type males (Ps < 0.005). There was no significant sex difference in the volume of the other three subdivisions of the VMH. Neuronal somata were larger in males than females in VMHvl, central VMH (VMHc) and the dorsomedial VMH (VMHdm), with TFM males having feminine neuronal somata in the VMHdm and VMHc. These data suggest that AR plays a role during sexual differentiation of the VMH, imparting its greatest effect in the VMHvl. ARs may regulate aromatase expression or activity to affect estrogen receptor activation, or may act independently of estrogen receptors to influence VMH morphology.

Original languageEnglish (US)
Pages (from-to)195-201
Number of pages7
JournalHormones and Behavior
Volume51
Issue number2
DOIs
StatePublished - Feb 1 2007
Externally publishedYes

Keywords

  • Androgen sensitivity
  • Brain
  • Laterality
  • Sex differences
  • Sexual dimorphism
  • Tfm

ASJC Scopus subject areas

  • Endocrinology
  • Behavioral Neuroscience
  • Neurology
  • Psychology(all)

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