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

The interrenal gland (the homologue of the mammalian adrenal cortex) of ela smobranchs (sharks, skates, and rays) produces 1 alpha-hydroxycorticosteron e (1 alpha-B), which has been reported to function both as a gluco- and min eralocorticosteroid. In vitro synthesis of 1 alpha-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 1 alpha-B synthesis, t hus demonstrating that the mechanism for the short-term induction of steroi dogenesis involved protein synthesis. However, gene transcription did not p lay a role in the short-term induction of 1 alpha-B synthesis, as indicated by the lack of an effect with actinomycin D treatment. Long-term in vitro exposure to pACTH (but not shortterm exposure) stimulated the synthesis of another steroid, 11-dehydrocorticosterone (A). This induction was partially blocked by cycloheximide and actinomycin D, which suggests enhanced expres sion of the 11 beta-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 3 beta-hydroxysteroid de hydrogenase and cytochrome P450 21-hydroxylase in D. sabina interrenals, ag ain suggesting the induction of steroidogenic genes. In contrast to other e lasmobranch species, the salmon and human forms of angiotensin II had no ef fect on D, sabina interrenal steroidogenesis. (C) 1999 Wiley-Liss, Inc.