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Search for other papers by D. R. IDLER in
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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.
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Search for other papers by D. R. IDLER in
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SUMMARY
Cortisol and cortisone were identified and their levels determined in sea raven plasma by a double isotope derivative assay involving acetylation with [1-3H]acetic anhydride, purification by thin-layer and paper chromatography, followed by recrystallization to constant 3H: 14C ratios. The mean level of cortisol in four plasma samples was 7·2±1·0 μg/100 ml (range 4·0–9·2) and the mean level for cortisone in three samples was 1·1 ± 0·2 μg/100 ml (range 0·7–1·5).
Metabolic clearance rates (MCR) were determined for both corticosteroids by the method of continuous infusion over an 8-h period. The mean MCR for cortisol in five fish was 126 ± 17 ml/kg/h, and for cortisone 449 ± 48 ml/kg/h in six fish. The mean percentage conversion of [1,2-3H]cortisol to cortisone was 9·4 ± 2·9%. There was no evidence of any significant conversion of cortisone to cortisol.
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Search for other papers by D. R. IDLER in
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SUMMARY
Fluorescence analyses and observations of plasma extracts on thin-layer chromatoplates including sulphuric acid chromogens failed to indicate the high concentrations of cortisol and corticosterone in Atlantic hagfish and sea lamprey reported by other workers. Double isotope derivative assays of Atlantic hagfish plasma and sea lamprey plasma failed to provide rigorous proof of the presence of these steroids.
Presumptive adrenocortical tissue from Atlantic hagfish and sea lamprey, incubated with radioactive steroids as precursors, failed to give any transformation to cortisol or corticosterone. However, sea lamprey incubations did produce 17α-hydroxyprogesterone from progesterone. No evidence was found for the presence of 17α-hydroxyprogesterone in microgram quantities in the plasma.
These findings are discussed in relation to previous studies in which high concentrations of cortisol and corticosterone were reported.
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Search for other papers by G. B. SANGALANG in
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SUMMARY
This report presents direct evidence for steroidogenesis by chondrostean tissue. The enzymes necessary for steroid transformation and cleavage of the cholesterol sidechain are present in yellow bodies isolated from the kidneys and along the posterior cardinal veins of the Atlantic sturgeon, Acipenser oxyrhynchus Mitchill.
Yellow bodies of the Atlantic sturgeon were incubated with [16-3H]pregnenolone plus [4-14C]progesterone in vitro and cortisol was formed in yields of 54·3 and 55·1% of the 3H and 14C precursor activities, respectively. Double-labelled cortisone, corticosterone, 11-deoxycortisol, 17α-hydroxyprogesterone and progesterone were isolated as transformation products but in relatively much lower yields. 11-Deoxycorticosterone, aldosterone and 1α-hydroxycorticosterone were not detected. When yellow bodies were incubated with [7-3H]cholesterol the following labelled transformation products were isolated: pregnenolone (0·43%), progesterone (0·091%), 17α-hydroxyprogesterone (0·023%), cortisol (0·061%), cortisone (0·004%), corticosterone (0·001%) and 11-deoxycortisol (0·047%). Again, 11-deoxycorticosterone, aldosterone, and 1α-hydroxycorticosterone were not detectable. All steroid products were identified by their isopolarity with authentic steroids by repeated chromatography, and by recrystallizations of free steroids and/or derivatives, after addition of authentic radio-inert steroids, to constant 3H:14C isotope ratios.
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SUMMARY
Yellow bodies scattered throughout the kidney tissue and posterior cardinal veins of the American Atlantic sturgeon Acipenser oxyrhynchus Mitchill were examined by histological and histochemical methods. Their histology resembled that of interrenal tissue, rather than that of corpuscles of Stannius.
The tissue was assayed histochemically for 3β-, 3α-, 11β-, 20β- and 20α-hydroxysteroid dehydrogenase (HSD) activity. Intense 3β-HSD activity was observed in the yellow bodies when dehydroepiandrosterone and pregnenolone were employed as substrates. Very weak 3α-HSD activity was observed with androsterone as a substrate. No 11β-HSD activity was observed with cortisol and corticosterone as substrates, and no 20α- or 20β-HSD activity when 20α- or 20β-hydroxyprogesterone respectively were employed as substrates.
These studies suggest that the yellow bodies found in the posterior cardinal veins and kidney tissue of A. oxyrhynchus Mitchill are true interrenal tissue.
Search for other papers by G. B. SANGALANG in
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Search for other papers by B. TRUSCOTT in
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Search for other papers by D. R. IDLER in
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SUMMARY
Cortisol was the principal steroid biotransformed from [16-3H]pregnenolone incubated with interrenal tissues of the Atlantic herring, Clupea harengus harengus, and of the Atlantic salmon, Salmo salar. Corticosterone was the preferred product from [4-14C]progesterone in herring, and cortisol in salmon. In these two teleosts 3H:14C recrystallization ratios of cortisol produced from the equimolar amounts of precursors at various times of incubation suggested that pregnenolone was the better precursor of cortisol and that the favoured pathway to cortisol was via 17-hydroxylated rather than 17-deoxy intermediates.
It was demonstrated that interrenal tissues of herring and salmon both have the capacity to 17-hydroxylate corticosterone to cortisol; aldosterone was not detected in any of the interrenal incubates. The 17-hydroxylation of 11-deoxycorticosterone to 11-deoxycortisol was shown in vitro by interrenal tissues of the Atlantic salmon, a conversion that has not been previously demonstrated in fish or in normal tissues of other vertebrates. When interrenal tissue of Atlantic salmon was incubated with equimolar amounts of [1,2-3H] 11-deoxycorticosterone plus [4-14C]corticosterone, there was more conversion of 11-deoxycorticosterone to 11-deoxycortisol (0·39%) than of corticosterone to cortisol (0·12%) and only a small amount (1·0%) of the 3H-labelled precursor was associated with corticosterone after 4 h incubation.
Biotransformed cortisol was isolated from both herring and salmon interrenals incubated with each of the following pairs of equimolar substrates: [3H]21-deoxycortisol plus [4-14C]11-deoxycortisol, [3H]21-deoxycortisol plus [4-14C]corticosterone, and [7-3H]11-deoxycortisol plus [4-14C]corticosterone. Isotope ratios of product cortisol suggested that, under the in-vitro conditions employed, substrate efficiency to cortisol synthesis was in the order: 11-deoxycortisol ⪢ 21-deoxycortisol > corticosterone. The results indicated that steroid hydroxylations at C-11, C-17 and C-21 could occur in any order in vitro in interrenals of herring and of salmon.
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Search for other papers by M. WEISBART in
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Search for other papers by D. R. IDLER in
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SUMMARY
Double isotope derivative assays were used to determine the presence or absence of testosterone, cortisol, cortisone, corticosterone, 11-deoxycortisol and 11-deoxycorticosterone in plasma samples from two (one sexually immature and one sexually mature) male American Atlantic sturgeon, Acipenser oxyrhynchus Mitchill. Submicrogram levels of testosterone were detected in the dichloromethane-extractable ('free' steroid) fractions of the plasma samples from both the immature and the mature fish; the level was much higher in the plasma of the mature fish. Very low levels of 'free' cortisol, cortisone and corticosterone were also detected in the plasma of the immature fish. The presence of 11-deoxycorticosterone and 11-deoxycortisol could not be firmly established in any of the samples. Preliminary analysis for conjugated testosterone in the plasma of the immature fish failed to show any detectable enzyme-released testosterone.
