Research On The Hormonal Mechanisms Regulating Sexual Behavior In Green Anoles

Earlier this year, we mentioned a paper by Juli Wade reviewing research on the green anole, which has become a model organism for integrative studies of reproductive behavior in vertebrates. One example of such research is a paper recently published in her laboratory by Cohen and Wade in which levels of testosterone were experimentally manipulated to see the effect of this hormone on gene expression in different regions of the brain. The abstract gives the details better than I could:

“Aromatase and 5alpha-reductase (5-alpha-R) catalyze the synthesis of testosterone (T) metabolites: estradiol and 5-alpha-dihydrotestosterone, respectively. These enzymes are important in controlling sexual behaviors in male and female vertebrates. To investigate factors contributing to their regulation in reptiles, male and female green anole lizards were gonadectomized during the breeding and non-breeding seasons and treated with a T-filled or blank capsule. In situ hybridization was used to examine main effects of and interactions among sex, season, and T on expression of aromatase and one isozyme of 5-alpha-R (5-alpha-R2) in three brain regions that control reproductive behaviors: the preoptic area, ventromedial nucleus of the amygdala and ventromedial hypothalamus (VMH). Patterns of mRNA generally paralleled previous evaluations of intact animals. Although no main effects of T were detected, interactions were present in the VMH. Specifically, the density of 5-alpha-R2 expressing cells was greater in T-treated than control females in this region, regardless of season. Among breeding males, blank-treated males had a denser population of 5-alpha-R2 positive cells than T-treated males. Overall, T appears to have less of a role in the regulation of these enzymes than in other vertebrate groups, which is consistent with the primary role of T (rather than its metabolites) in regulation of reproductive behaviors in lizards. However, further investigation of protein and enzyme activity levels are needed before specific conclusions can be drawn.”

About Jonathan Losos

Professor and Curator of Herpetology at the Museum of Comparative Zoology at Harvard University. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.

2 thoughts on “Research On The Hormonal Mechanisms Regulating Sexual Behavior In Green Anoles

  1. What is known about the impact of testosterone on development of secondary sexual characteristics like the dewlap? Some folks in my lab are assembling a fascinating new dataset on the factors responsible for dewlap size variation of captive anoles. They’ve been manipulating housing conditions, but haven’t done any hormone manipulation.

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