Sex differences in the effects of pregnenolone, progesterone, and ACTH on corticosterone secretion of bank vole (Clethrionomys glareolus) adrenals in tissue culture

Possible sex-specific differences in the basal as well as the pregnenolone-, progesterone-, and ACTH-induced glucocorticoid secretion of bank vole adrenals was studied in tissue culture by column and gas–liquid chromatography. The adrenals were cultured for 12 days and the medium was replaced after 6 days. The main glucocorticoid in this species, as in many other rodents, seems to be corticosterone since no cortisol was detected. During the first 6 days of cultivation, the administration of pregnanes (20 μg as a single dose) as well as ACTH (0.1 IU∙mL−1∙day−1) induced a marked increase (P < 0.01 or P < 0.001) in the corticosterone secretion in both sexes. The basal as well as the pregnenolone- and the ACTH-induced secretion of corticosterone was significantly (P < 0.02 or P < 0.01) greater in female than male adrenals. These functional differences were almost totally abolished after 12 days of culture. This study suggests that despite the existence of a 3β-hydroxysteroid dehydrogenase negative juxtamedullary zone (at least by histochemical criteria), female adrenals have a greater capacity to convert endogenous as well as exogenous precursors to corticosterone than male adrenals. This is at least partly due to sex differences in the activity (per gland) of the steroidogenic enzymes distal to cholesterol side-chain cleavage, 3β-hydroxysteroid Δ5-Δ4-isomerase in particular.