In vitro inhibition of estradiol secretion of tadpole ovaries by cyanoketone

• Published in: General and comparative endocrinology Vol. 69; no. 1; pp. 41 - 45
• Main Authors: Hsu, C.Y., Chang, L.T., Yu, N.W., Ku, H.H., Lu, M.H.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 1988; Elsevier
• Subjects: Androstenols - pharmacology; Animals; Biological and medical sciences; Cyanoketone - pharmacology; Estradiol - metabolism; Female; Freshwater; Fundamental and applied biological sciences. Psychology; Histocytochemistry; In Vitro Techniques; Larva - drug effects; Larva - metabolism; Non mammalian vertebrate reproduction; Ovary - drug effects; Ovary - metabolism; Radioimmunoassay; Rana catesbeiana; Rana catesbeiana - metabolism; Vertebrates: reproduction; Enzyme; Frog; Amphibia; Salientia; In vitro; Estradiol; Pregnenolone; Ovary; Vertebrata; Synthetic product; Analog; Female genital system; Steroidogenesis; Inhibition; Sex steroid hormone
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1016/0016-6480(88)90050-0

We have demonstrated the presence of Δ 5-3β-hydroxysteroid dehydrogenase (HSD) activity in tadpole ovaries of Rana catesbeiana. In the present study, we wish to determine whetherestradiol (E 2) secretion of tadpole ovaries could be influenced by cyanoketone (CK), a specific inhibitor of Δ 5-3β-HSD. R. catesbeina tadpoles at the premetamorphic climax were used, and pooled ovaries were incubated, 30 mg/tube, with CK at dosages of 0, 0.001, 0.01, 0.1, 1, and 10 μg/ml of Krebs-Ringer bicarbonate buffer for 6 hr. Media were collected for assay of E 2 by radioimmunoassay (RIA). Results showed an inhibition of E 2 secretion by CK that was positively correlated with CK dosage, but plateaued at doses of 0.1 μg/ml and higher. This finding was comparable to that of G. F. Young, H. Kagawa, and Y. Nagahama (1982, Gen. Comp. Endocrinol. 47, 357–360) on adult fish ovaries. However, adult vertebrates depend on gonadotropins to regulate secretion of E 2 while tadpoles, being immature, might secrete E 2 independently of pituitaries. When the histochemical test for Δ 5-3β-HSD activity was performed on in vitro CK-treated ovaries, there was a decrease of enzyme activity by CK. The RIA and histochemical findings may contribute to the concept of sex transformation in which a disturbance of steroidogenesis may induce sex reversal from females to males, at least in tadpoles.