MODULATION OF AROMATASE EXPRESSION BY ANDROGEN RECEPTORS IN THE AFRICAN CICHLID Astatotilapia burtoni

Date
2023-12
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Abstract

Social behaviors are regulated by sex steroid hormones such as androgens and estrogens. However, the specific molecular and neural processes modulated by sex steroid hormones to generate social behaviors remain to be elucidated. We investigated whether some androgenic actions in the control of social behavior may occur through the regulation of estradiol synthesis in the African cichlid Astatotilapia burtoni. Due to a teleost-specific whole-genome duplication event, A. burtoni has two functional androgen receptor (AR) genes, ARa and ARb. Here, we examined the expression of cyp19a1, a brain-specific aromatase, in the brains of male and female A. burtoni lacking a functional ARa gene. Specifically focusing on brain regions within the social behavior network (SBN) which are key in the production of social behavior. We found that cyp19a1 expression is dependent on the sex and brain region analyzed, with ARa mutant males showing differences only in the homolog of the ventromedial hypothalamus (VMH), a brain region that governs aggression across taxa, while ARa mutant females showed differences in both the Preoptic area (POA) and the partial homolog of the Bed nucleus of the stria terminalis (BNST) (the Vs). Furthermore, through in situ hybridized chain reaction (HCR), we determined that cyp19a1+ cells commonly co-express ARa in both males and females in brain regions relevant to behavior like the POA, VMH, and Vs. We speculate that ARa may modulate cyp19a1 expression distinctively depending organizational effects of steroid hormones during development. These studies provide novel insights into the hormonal mechanisms of social behavior and lay a foundation for future functional studies.

Description
Keywords
brain aromatase, social behavior, sex differences
Citation
Portions of this document appear in: Lopez, Mariana S., and Beau A. Alward. "Androgen receptor deficiency is associated with reduced aromatase expression in the ventromedial hypothalamus of male cichlids." Annals of the New York Academy of Sciences (2024).