Cloning and in situ hybridization analysis of estrogen receptor, progesterone and androgen receptor expression in the brain of whiptail lizards (Cnemidophorus uniparens and C. inornatus)

Abstract

Gonadal steroid hormones act upon specific areas of the vertebrate brain to affect the reproductive physiology and behavior of the animal. Steroid receptors are members of a superfamily of ligand-dependent transcription factors that mediate the effects of steroid hormones by modulating gene expression in the cells containing the receptors. The neuroanatomical distributions of steroid receptor-containing cells have been described for several species by using steroid autoradiography, immunocytochemistry, and more recently in situ hybridization. We have used the polymerase chain reaction to amplify and clone fragments of the estrogen receptor, progesterone receptor, and androgen receptor of whiptail lizards (genus Cnemidophorus). These clones were used to produce probes for use in in situ hybridization assays and to map the neuroanatomical distribution of all three sex steroid hormone receptors in the forebrains of unisexual (C. uniparens) and sexual (C. inornatus) species of whiptail lizards. The distribution of receptor-expressing cells reported here is in general agreement with previous reports in other species with receptor-containing cells concentrated in septal, amygdaloid, cortical, preoptic, and hypothalamic nuclei.

The Vertebrate mesolimbic reward system and social behavior network: A comparative synthesis

“…Reptilian vomeronasal information is relayed to the pallial nucleus sphericus and subpallial medial amygdala , and these regions send projections through the stria terminalis to the hypothalamus, as is characteristic of the mammalian meAMY Martinez-Marcos et al, 1999). This reptilian homolog is neurochemically similar to the mammalian meAMY (Table 3) and contains sex steroid hormone receptors (Young et al, 1994;O'Connell et al, 2011c). Additionally, neurochemical evidence supports the subpallial origin of the reptilian meAMY (Table 3) (Moreno et al, 2010).…”

“…The POA contains sex steroid hormone receptors (Young et al, 1994;O'Connell et al, 2011c) and is a central integration point for telencephalic regions and the hypothalamus (Russchen and Jonker, 1988;Smeets et al, 1995). This region is also functionally similar to the mammalian POA, as implants into the POA of either testosterone or DHT in castrated male lizards increase sexual behavior (Morgantaler and Crews, 1978;Rozendaal and Crews, 1989), while lesions of the POA decrease courtship behavior (Kingston and Crews, 1994).…”

“…In both lineages it is located caudal to the POA along the third ventricle, but rostral to the VMH, and contains sex steroid hormone receptors (Young et al, 1994;Beck and Wade, 2009). There have been many lesion studies that have included the AH that support its role in sexual behavior and aggression (Morgantaler and Crews, 1978); however, these are usually combined lesions of both POA and AH, making it difficult to dissect the functional mechanisms of the AH alone.…”

“…The reptilian VMH homolog is topographically located along the third ventricle in the ventrocaudal hypothalamus and contains sex steroid hormone receptors (Young et al, 1994;O'Connell et al, 2011c). This region is also highly interconnected with the hypothalamus and amygdaloid nuclei (Bruce and Neary, 1995a,b), and appears to also be functionally similar to the mammalian VMH, as lesions decrease receptivity in female dessert grassland lizards (Cnemidophorus uniparens; Kendrick et al, 1995).…”

Serotonergic modulation of male-like pseudocopulatory behavior in the parthenogenetic whiptail lizard, Cnemidophorus uniparens

“…Using a cryostat (Microm HM 500 OM), 200-μm coronal sections were thaw mounted onto Superfrost Plus slides (Erie Scientific, USA). Sections were then rapidly frozen using a cooling block set at −20°C (Physitemp Instruments Inc., USA), and the POA was dissected using a 300-μm diameter micropunch, as per Smeets and Steinbusch (1988) and Young et al (1994). Tissue samples from each animal were assayed independently of each other and not pooled.…”