Meeting Abstract

12.8  Thursday, Jan. 3  Gonadal and Nutritional Modulation of Adrenocortical Cellular Steroidogenesis in Sceloporus Lizards JOHN-ALDER, H.**; CARSIA, R.; COX, R.; BARRETT, M.; MCILROY, P.; Rutgers Univ., New Brunswick; UMDNJ, Stratford; Dartmouth Col., Hanover; Rutgers Univ., New Brunswick; Rutgers Univ., Camden henry@aesop.rutgers.edu

Variation in plasma glucocorticoids is ubiquitous, but the importance of malleability in adrenocortical cells has only recently been recognized. We analyzed effects of gonadectomy with and without testosterone (T) replacement on steroidogenesis in adrenocortical cells isolated from males of S. jarrovii and S. undulatus and females of S. virgatus, and we compared females versus males in the latter species. As measured by the production of progesterone (P4), corticosterone (B), and aldosterone (ALDO), cellular sensitivity to corticotrophin (ACTH) was lower in control male than female S. virgatus and was reduced by all treatments in all species except orchiectomy without T replacement in field-active S. undulatus (no effect). Maximal rates of steroid production were lower in males than in females of S. virgatus and were dramatically reduced by T replacement in orchiectomized S. undulatus males. Thus, just as adrenal glucocorticoids can influence endocrine and reproductive functions of the gonads, gonadal steroids can modify adrenal steroidogenesis. In the second set of studies, we analyzed effects of chronic, non-debilitating food restriction on adrenocortical cellular function in males and females of S. jarrovii. Food restriction cut growth rate in half but had no effect on plasma corticosterone measured after 10 weeks. Maximal rates of P4, B, and ALDO production in response to ACTH were increased about two-fold by food restriction, but cellular sensitivity to ACTH was unaffected. Overall, these studies emphasize the potential importance of variation in adrenocortical cellular steroidogenesis to changes in HPA output. Supported by NSF IBN-0135167