Effects of season, testosterone and female exposure on c-fos expression in the preoptic area and amygdala of male green anoles

Abstract

Expression of the immediate early gene, c-fos, was used to investigate changes in neuronal activity in forebrain regions involved in male sexual behavior following social, hormonal and/or seasonal manipulations in the male green anole. These factors all influence behavior, yet it is unclear how they interact to modify neuronal activity in forebrain regions, including the preoptic area (POA) and ventromedial nucleus of the amygdala (AMY). These regions are involved in the display of sexual behaviors in male green anoles as in many other vertebrates. To determine the effects of seasonal, hormonal and social cues on these brain areas, we investigated c-fos under environmental conditions typical of the breeding or non-breeding season in adult male green anoles that were castrated and implanted with either testosterone (T) or blank (Bl) capsules. We also manipulated social cues by exposing only half of the animals in each group to females. T enhanced courtship and copulatory behaviors, but decreased c-fos expression in the AMY. A similar, although not statistically significant, pattern was observed in the POA, and the density of c-fos+ cells was negatively correlated in that region with the number of extensions of a throat fan (dewlap) used during courtship. Therefore, it appears that in the male green anole, T may diminish c-fos expression (likely in inhibitory neurons) in the POA and AMY to create a permissive environment in which the appropriate behavioral response can be displayed.

Androgenic control of male-typical behavior, morphology and sex recognition is independent of the mode of sex determination: A case study on Lichtenfelder's gecko (Eublepharidae: Goniurosaurus lichtenfelderi)

“…Evidence from neuroendocrine studies in lizards suggest that T alters the activity of neurotransmitter systems that may modulate motivation for social interaction and sexual behavior (Neal and Wade, 2007;Wade, 2011;O'Connell et al, 2012). Our results in G. lichtenfelderi support this idea because castrated males were active in the neutral arena but not as motivated to interact with the female compared to males with elevated T levels.…”

Estradiol induces region-specific inhibition of ZENK but does not affect the behavioral preference for tutored song in adult female zebra finches

“…For example, Tetel et al [89] and Pfaus et al [70] observed decreases in the induction of FOS-IR following small amounts of vaginocervical stimulation in the VMH when female rats were treated with estradiol. In addition, a decrease in immediate early gene expression in the preoptic area and amygdala occurs following testosterone administration in male anole lizards [59]. …”

Telencephalic Neuronal Activation Associated with Spatial Memory in the Terrestrial Toad <b><i>Rhinella arenarum:</i></b> Participation of the Medial Pallium during Navigation by Geometry

“…Bailey et al, 2002;Neal and Wade, 2007;Huang et al, 2013], as well as other amphibians (i.e. the salamander Plethodon shermani [Laberge et al, 2008] and Xenopus laevis [Calle et al, 2006]).…”

“…We also examined the amygdala and the bed nucleus of the stria terminalis, both of which were characterized by low numbers of labeled cells (not reported) that visually did not vary across the three treatment groups. Only complete diameter and clearly stained nuclei were counted, following closely the procedures of Neal and Wade [2007].…”