Cortisol effects on the testicular androgen synthesizing capacity in common carp, Cyprinus carpio L.
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Our previous studies on the effect of stress on pubertal development in carp have shown that repeated temperature changes caused an increase in cortisol levels and a retardation of the first waves of spermatogenesis. Identical effects, accompanied by a decrease in 11-ketotestosterone (11KT) plasma levels and the gonadosomatic index (GSI) were induced by cortisol administration via cortisol containing food pellets. The decrease in plasma 11KT is caused by a direct effect of cortisol on the steroid producing capacity of the testis, independent of luteinizing hormone (LH) levels. However, the mechanism through which cortisol interferes with testicular steroidogenesis is unknown. In the present study, we showed that in vitro physiological levels of cortisol can inhibit the conversion of 11β-hydroxyandrostenedione (OHA) into androstenetrione (OA), which is the precursor of 11KT, possibly by competing for the enzyme 11β-hydroxysteroid dehydrogenase (11β-HSD). The same mechanism may occur in vivo. However, our results demonstrate that an elevation of plasma cortisol levels during acute cortisol treatment did not result in lower plasma levels of OA and 11KT, but we did observe an accumulation of OHA. We suggest that the previously observed decrease in 11-oxygenated androgens, as an effect of long-term cortisol treatment, is caused by a retardation of testicular development. This results in a lower steroid synthesizing capacity of the testis as a whole. Although the in vitro observed cortisol inhibition of the conversion of OHA into 11KT plays a role in the accumulation of OHA, it apparently has no effect on the final 11KT plasma concentration.
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- Consten, D., Lambert, J.G.D. and Goos, H.J.Th. 2000. Inhibitory effects of cortisol on in vivo and in vitro androgen secretion in male common carp, Cyprinus carpio. In: Proceedings of the 6th International Symposium on the Reproductive Physiology of Fish. p.192. Edited by B. Norberg, O.S. Kjesbu, G.L. Taranger, E. Andersson and S.O. Stefansson S.O. Bergen, Norway.Google Scholar
- Consten, D. 2001. Stress response and pubertal development in the male common carp, Cyprinus carpio L. Thesis. University of Utrecht, Utrecht, The Netherlands.Google Scholar
- De Man, A.J.M., Hofman, J.A., Hendriks, Th., Rosmalen, F.M.A., Ross, H.A. and Benraad, Th.J. 1980.A direct radioimmunoassay for plasma aldosterone: significance of endogenous cortisol.Neth. J. Medicine23:79–83.Google Scholar
- Schulz, R.W., Lubberink, K., Zandbergen, M.A., Janssen-Dommerholt, C., Peute, J. and Goos, H.J.Th. 1996. Testicular responsiveness to gonadotropic hormone in vitro and Leydig and Sertoli cell ultrastructure during pubertal development of male African catfish (Clarias gariepinus).Fish Physiol. Biochem.15: 243–254.CrossRefGoogle Scholar