JOHN-ALDER, H.B.*; CARSIA, R.V.: Partial Characterization of Adrenocortical Cells from the Eastern Fence Lizard (Sceloporus undulatus)

Season-specific corticosterone responses are apparent in S. undulatus (Horm. Behav. 36:39-52, 1999). These varying responses may be due to season-related adrenal programming. As a beginning point to investigate this hypothesis, we partially characterized the steroidogenic properties of adrenal cells derived from male lizards collected in September, 2000. Adrenal glands were dissociated using collagenase digestion and mechanical agitation. ‘Adrenocortical’ cells were easily identified by their numerous large lipid droplets. Cells (1×105 adrenocortical cells/ml) were incubated with various test substances for 2 h at 34.5�C. Incubations were frozen (-30�C) until radioimmunoassay for corticosterone and aldosterone. Cells exhibited high constitutive steroidogenic activity with basal corticosterone and aldosterone values of ~ 4 ng/103 cells/h and 40 pg/103 cells/h, respectively. Although inducible responses were blunted (roughly twice basal values), cells were exquisitely sensitive to adrenocorticotropin (ACTH), responding to concentrations as low as 1 pM. Cells also responded to 8-bromo-cyclic AMP, but not to angiotensin II or the steroidogenic precursor, 25-hydroxycholesterol. The lack of a precursor response is suggestive of a saturated steroidogenic enzyme pool and is consistent with the high constitutive activity. Although it is unclear whether the overall responses of the lizard cells are related to season, this study demonstrates that this in-vitro approach may be useful to resolve the hypothesis of season-specific adrenal programming. Supported by NSF IBN95-05729 to H. J.-A. and USDA 00-35206-9330 to R. V. C.