Sexually dimorphic estrogen receptor alpha mRNA expression in the preoptic area and ventromedial hypothalamus of green anole lizards.
Estradiol (E2) is important in activation of male reproductive behaviors, and masculinizes morphology of associated brain regions in a number of mammalian and avian species. In contrast, it is testosterone, rather than its metabolites, that is the most potent activator of male sexual behavior in green anole lizards. As in other vertebrate groups, however, E2 is critical for receptivity in females of this species. Aromatase, the enzyme which converts testosterone to E2, is more active in the male than female green anole brain, and appears to be actively regulated on a seasonal basis, suggesting some role for E2 in males. This study was designed to enhance our understanding of potential E2 actions by localizing and quantifying relative levels of estrogen receptor-alpha (ERalpha) mRNA in forebrain regions involved in masculine and feminine behaviors in anoles. These areas include the preoptic area (POA), ventromedial amygdala (AMY) and ventromedial hypothalamus (VMH). In situ hybridization was conducted in adult males and females collected during both breeding and non-breeding seasons. ERalpha mRNA was expressed in each brain region across sexes and seasons. However, expression was up to 3 times greater in the VMH compared to the POA and AMY. In the POA and VMH, expression was higher in females compared to males, independent of season. The increased receptor expression in females is consistent with E2 playing a larger role in female than male reproductive behaviors.
Beck
Laurel A
LA
Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA. becklau2@msu.edu
Wade
Juli
J
D000679:Amygdala / Q000254:growth & development / Q000378:metabolism; D000818:Animals; D001923:Brain Chemistry / Q000502:physiology; D047628:Estrogen Receptor alpha / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D017403:In Situ Hybridization; D008116:Lizards / Q000502:physiology*; D008297:Male; D011301:Preoptic Area / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D012621:Seasons; D012727:Sex Characteristics; D014697:Ventromedial Hypothalamic Nucleus / Q000378:metabolism*
D047628:Estrogen Receptor alpha; D012333:RNA, Messenger