Regulation of interrenal gland steroidogenesis in the Atlantic stingray (Dasyatis sabina)

The interrenal gland (the homologue of the mammalian adrenal cortex) of elasmobranchs (sharks, skates, and rays) produces 1alpha-hydroxycorticosterone (1alpha-B), which has been reported to function both as a gluco- and mineralocorticosteroid. In vitro synthesis of 1alpha-B by Atlantic stingray (Dasyatis sabina) interrenal glands was stimulated by short-term (2 hr) and long-term (24 hr) treatment with porcine adrenocorticotropic hormone (pACTH). Cycloheximide blocked the pACTH-induced effect on 1alpha-B synthesis, thus demonstrating that the mechanism for the short-term induction of steroidogenesis involved protein synthesis. However, gene transcription did not play a role in the short-term induction of 1alpha-B synthesis, as indicated by the lack of an effect with actinomycin D treatment. Long-term in vitro exposure to pACTH (but not short-term exposure) stimulated the synthesis of another steroid, 11-dehydrocorticosterone (A). This induction was partially blocked by cycloheximide and actinomycin D, which suggests enhanced expression of the 11beta-hydroxysteroid dehydrogenase gene. In addition, the 24-hr treatment with pACTH enhanced the activity of cytochrome P450 side chain cleavage several fold and doubled the activity of 3beta-hydroxysteroid dehydrogenase and cytochrome P450 21-hydroxylase in D. sabina interrenals, again suggesting the induction of steroidogenic genes. In contrast to other elasmobranch species, the salmon and human forms of angiotensin II had no effect on D. sabina interrenal steroidogenesis. J. Exp. Zool. 284:517-525, 1999.