Meeting Abstract

P1.41  Wednesday, Jan. 4  Sexually dimorphic mRNA levels of genes involved in arginine vasotocin and sex steroid signaling in the brain of Xenopus tropicalis MIRANDA, RA*; PROPPER, CR; Northern Arizona University; Northern Arizona University

The arginine vasotocin (AVT)/arginine vasopressin neuropeptide system interacts with sex steroids to mediate social behaviors in vertebrates. Additionally, both the expression of behavior and expression of these neuroendocrine signaling systems is sexually dimorphic across clades. The purpose of this study was to compare mRNA abundance of genes important for AVT and estrogen signaling in the brain between adult male and female Xenopus tropicalis. Brains from each sex (n=10) were collected and later macrodissected into five areas: hindbrain, thalamus/hypothalamus, preoptic area, lateral telencephalon and medial telencephalon. Total RNA was then extracted from each brain area and cDNA was synthesized from mRNA. Quantitative real-time PCR was used to measure mRNA abundance of AVT precursor peptide (VT), AVT 1a receptor (V1a), estrogen receptor α (ERα) and aromatase (CYP19). A difference in mRNA levels was seen between sexes. Males expressed more V1a mRNA in the medial telencephalon (Student’s t-test, p=0.045). Males also showed higher transcript abundance in the preoptic area for both VT (Mann-Whitney U test, p=0.014) and CYP19 (Mann-Whitney U test, p=0.022). Females showed more mRNA abundance for ERα (Mann-Whitney U test, p=0.05) and CYP19 (Mann-Whitney U test, p=0.021) in the hindbrain. No difference in mRNA levels was seen between sexes for all other genes analyzed anywhere in the brain. Our results demonstrate that there is sexually dimorphic mRNA abundance for genes involved in AVT and estrogen signaling in the brain of X. tropicalis and suggest estradiol synthesis may interact with brain AVT signaling pathways.