Biogenesis of Corticosteroids in the European Eel Anguilla Anguilla L.

Abstract

SUMMARY Incubation, with [4-14C]progesterone, of adrenocortical tissue (posterior cardinal vein preparations) from the eel yielded 14C-labelled cortisol and cortisone. These two hormones, containing both 14C and 3H, appeared when similar preparations were incubated simultaneously with [4-14C]progesterone and [16-3H]pregnenolone. In addition, the following intermediaries were isolated: [14C, 3H]progesterone; [14C, 3H]17α-hydroxyprogesterone; [3H]17α-hydroxypregnenolone and [14C, 3H]21-deoxycortisol. Analysis of the isotope content of the end products and isolated intermediaries seemed to indicate that the transformation of pregnenolone to corticosteroids proceeded to a large extent through intermediaries other than progesterone. In none of these experiments could the formation of aldosterone be demonstrated. Similarly, incubation of eel adrenocortical tissue with a mixture of [4-14C]-progesterone and [1,2-3H]corticosterone failed to yield detectable aldosterone. A further search for aldosterone, using a large amount of eel adrenocortical tissue with [4-14C]progesterone and [16-3H]pregnenolone as substrates with added angiotensin, also gave negative results. In similar preparations, [1-14C]sodium acetate was not transformed to any recognizable corticosteroids.

Interrenal steroid 21-hydroxylase in eels: primary structure, progesterone-specific activity and enhanced expression by ACTH

“…Actually, the eel interrenal tissue actively converted 3 Hcorticosterone to cortisol in this study. 17 -Hydroxylation of corticosterone to produce cortisol has previously been reported in fish including the European eel (Sandor et al 1966). Together with the present data, it seems that the route for cortisol biosynthesis from progesterone through Fig.…”

“…In vitro tissue incubation experiments have shown that progesterone is converted to 11-deoxycorticostrone in the interrenal of the European eel (Sandor et al 1966). Therefore, an enzyme activity similar to that of the cloned P450c21 also appears to be present in the interrenal of this species of eel.…”

“…In the eel, the interrenal cells are closely associated with blood vessels of the head kidney (Sandor et al 1966, Takashima & Hibiya 1995. The head kidney of the eel is a long tissue that extends from the kidney to the heart and spans more than 20% of the total body length.…”

“…However, indirect evidence from in vitro studies has indicated that in elasmobranchs, amphibians, reptiles and birds, progesterone is the major substrate of P450c21 because of the absence of P450c17 in the adrenal/interrenal of these groups (Lofts & Bern 1972, Nunez & Trant 1995. In teleosts, limited studies suggest that both progesterone and 17 -hydroxyprogesterone may be 21-hydroxylated in the interrenal (Sandor et al 1966, Idler & Truscott 1972. However, the preferential substrate of P450c21 might differ with species, developmental stage and season (Lofts & Bern 1972, Sangalang & Uthe 1994.…”

The mislabelling of deoxycorticosterone: making sense of corticosteroid structure and function

“…It is particularly interesting that DOC is present in the teleost fish, which, conversely, generally do not make aldosterone (but see Whitehouse & Vinson (1975)), and for this reason, it has been speculated that DOC, which binds strongly to the fish MR, may be their primary mineralocorticoid (Sturm et al 2005). This is controversial, the teleost 17-hydroxylase is fairly non-specific (Sandor et al 1966, Sangalang et al 1972, and 17-deoxysteroids, including DOC, are not in abundance: most authors believe that cortisol is the major teleost mineralocorticoid as well as glucocorticoid (Wendelaar Bonga 1997, McCormick et al 2008. On the other hand, DOC together with 11-deoxycortisol is apparently present, whereas corticosterone, aldosterone and cortisol are absent, in the plasma of the lamprey, and Close et al (2010) conclude that 11-deoxycortisol is the major corticosteroid in this species, with both glucocorticoid and mineralocorticoid actions.…”