Steroid metabolism by ovarian follicles of the tilapia Oreochromis mossambicus (Teleostei, Cichlidae)

• Type: Article in International Scientific Journal
• Date: 1998

Authors

rocha, mj (Author) Other; reis-henriques, ma (Author) Other

Journal

Title: COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY

Vol. 121

Pages: 85-90

ISSN: 0305-0491

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 11 Citations

Scopus - 10 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-001-74Z

DOI: 10.1016/S0305-0491(98)10130-X

Abstract (EN): Female tilapia, Oreochromis mossambicus, were treated with luteinizing hormone-releasing hormone analogue (LH-RHa) and pimozide (PIM) to stimulate gonadal development and sexual maturation. Twenty-four hours after LH-RHa + PIM or vehicle (controls) injections, ovarian samples were collected for the in vitro incubations. Stage III or Stage IV follicles were treated with either 1) 20 mu g tilapia hypophysis plus 50 ng 17-hydroxyprogesterone (17-P), 2) 20 mu g hypophysis alone, 3) 50 ng 17-P alone and 4) media alone. Free and conjugated (sulfates and glucuronides) levels of the established teleost oocyte maturation inducing steroids (MIS), i.e. 17,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta-P) and 17,20 beta,21-trihydroxy-4-pregnen-3-one (17,20 beta,21-P) were measured in the incubation media by high performance liquid chromatography. The highest levels' of 17,20 beta-P, in both free and conjugated forms, were measured in media containing Stage IV follicles (up to 7 ng/ml; P < 0.01). Free levels of 17,20 beta,21-P were detectable only in incubates of Stage III follicles (up to 1 ng/ml). The levels of conjugated 17,20 beta-P and 17,20P,21-P were higher as sulfates than as glucuronides for all incubates. These results demonstrate that 17,20 beta-P and 17,20P,21-P are synthesized in vitro by follicles of tilapia and that sulfation is the main route for the metabolism of the C-21-steroids. The high levels of 17,20 beta-P and 17,20 beta-P-sulfate in incubates containing Stage IV follicles points at 17,2Q beta-P, rather than 17,20P,21-P, as the most probable MIS in tilapia and suggests a probable pheromone role for free 17,20 beta-P and 17,20 beta-P-sulfate in this species. (C) 1998 Elsevier Science Inc. All rights reserved.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6