JOHN-ALDER, H.B.*; CARSIA, R.V.; Rutgers Univ., New Brunswick; UMDNJ School of Osteopathic Medicine, Stratford: Inflence of the Testis on Adrenocortical Cell Function in Sceloporus undulatus (Eastern Fence Lizard)

Adrenal steroidogenic cells from male Sceloporus undulatus undergo dramatic seasonal changes in sensitivity to ACTH. Here, we examine possible testicular influences on adrenocortical cell function. Intact (CON) and orchiectomized males with empty Silastic implants (ORCHX) or implants initially containing 300 ug of testosterone (ORCHT) were released into an enclosed area in the New Jersey pinelands at about 10 months of age. Thirteen months later, 3 CON, 3 ORCHX, and 2 ORCHT were recaptured, and dispersed adrenocortical cells were prepared for evaluation of corticosteroid responses to adrenocorticotrophic hormone (ACTH). Basal and net maximal rates of corticosterone (B) production in response to ACTH did not differ between CON and ORCHX cells but were reduced 35 and 56%, respectively, in ORCHT. Differences in aldosterone (ALDO) production were even more dramatic. Basal and net maximal rates of ALDO production were respectively 47 and 86% greater in ORCHX than in CON but were reduced 84 and 74% in ORCHT. Sensitivity to ACTH (ACTH ED₅₀) did not differ between CON and ORCHX but was reduced ~90% in ORCHT compared to CON and ORCHX. These initial findings suggest that the long-term absence of the testes does not influence B production and sensitivity to ACTH in adrenocortical cells. In the absence of the testes, testosterone maintenance is a strong suppressor of adrenocortical cell function and sensitivity to ACTH. We postulate that testosterone, perhaps accompanied by other testicular factors and/or more proximal testicular controls, modulates adrenocortical cell function in S. undulatus. Supported by NSF IBN0135167 to H. J.-A. and USDA 00-35206-9330 to R.V.C.