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The effects of testosterone exposure on urogenital tract androgen receptor distribution in immature eastern fence lizards

Abstract

Androgens are important to the development and maintenance of reproductive structures and functions; however, less is known about the importance of androgen signaling in females compared to males. The distribution of androgen receptors (ARs) in mammalian urogenital systems has been characterized but relatively little is known about AR expression in non-mammalian vertebrates. In this study, AR was immunolocalized in the urogenital tracts of juvenile eastern fence lizards, Sceloporus undulatus. A subset of lizards received testosterone implants to understand and examine the effects of elevated testosterone (T) on AR expression. Our results showed control males had moderate AR-positive staining within the epididymal epithelium and diffuse staining throughout the testes, with minor staining surrounding the sexual segments of the kidney. Control females revealed a similar intensity of staining within their oviduct and mesonephric ducts. Elevated T in lizards that received implants led to hypertrophied reproductive tracts and increased AR expression throughout most of the urogenital system. As compared to control males, males that received exogenous T revealed darker AR staining in the testis, spermatic ducts, and the sexual segments of the kidney. Androgen receptor staining was more intense and concentrated in the nuclei of the epithelia of the oviducts and ductus deferentia of T-treated females in comparison to controls. Our results demonstrate that the urogenital tracts of both sexes are androgen sensitive, and the tissues that responded the most dramatically to elevated T were the same tissues that had the most intense AR staining. Our results also suggest that exposure to elevated T concentrations leads to upregulation of AR expression and increased nuclear translocation. Although oviducts of T-treated females exhibited hypertrophy relative to untreated females and were AR positive, it is unclear if this was through direct actions of testosterone or the aromatization of androgens to estrogens.

Acknowledgements

Robert Cox Lab, University of Virginia

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