THE WIDESPREAD OCCURRENCE OF A CORTICOSTEROID 1α-HYDROXYLASE IN THE INTERRENALS OF ELASMOBRANCHII

Abstract

SUMMARY: A corticosteroid 1α-hydroxylase was demonstrated in interrenal tissue of eleven species of elasmobranchs by the production in vitro of 1α-hydroxycorticosterone from corticosterone, and in seven of nine species examined from endogenous precursors. Interrenal tissue was collected from the following species: the skates and rays, Raja laevis, R. clavata, R. erinacea, and Dasyatis violacea; the dogfish, Squalus acanthias and Scyliorhinus stellaris; and the sharks, Isurus oxyrinchus, Prionace glauca, Sphyrna lewini, Carcharhinus falciformis and C. obscurus. 1α-Hydroxycorticosterone was identified in interrenal incubates by determination of a constant isotope ratio (³H:¹⁴C) through chromatography and preparation of sequential derivatives. [7α-³H] 1α-Hydroxycorticosterone was biosynthesized from [7α-³H]progesterone and its identity verified by demonstration of the homogeneity of its 1-dehydrated derivative with 11β,21-dihydroxypregna-1,4-diene-3,20-dione prepared by microbial dehydrogenation of corticosterone. ¹⁴C-Labelled 1α-hydroxycorticosterone was obtained from incubations of interrenal glands as a transformation product of [4-¹⁴C]corticosterone, or by acetylation of radioinert 1α-hydroxycorticosterone with [1-¹⁴C]acetic anhydride. 11-Deoxycorticosterone and corticosterone were isolated and identified as metabolites of endogenous precursors from an interrenal incubate of P. glauca. In all species, 11-dehydrocorticosterone was noted as a metabolite in vitro of corticosterone and its identity was confirmed in an interrenal incubate of S. lewini. The results of this survey are discussed in relation to earlier studies of steroidogenesis in Elasmobranchii.