title: The skin of the male African catfish, Clarias gariepinus: a source of steroid glucuronides.
abstract: Steroid metabolism in the skin of mature male African catfish, Clarias gariepinus, reared in the laboratory, was studied in vitro by tissue incubations with [3H]pregnenolone, [3H]dehydroepiandrosterone, [3H]17 alpha-hydroxyprogesterone, [3H]androstenedione, [14C]11 beta-hydroxyandrostenedione, and [3H]testosterone as precursors. While pregnenolone was not converted to any other steroid, dehydroepiandrosterone was transformed mainly to 5-androstene-3 beta, 17 beta-diol. The products of 17 alpha-hydroxyprogesterone incubations were 5 beta-pregnane-3 alpha,17 alpha-diol-20-one, 5 beta-pregnane-3 alpha,17 alpha, 20 beta-triol, and 5 beta-pregnan-17 alpha-o1-3,20-dione. The major steroids of androstenedione incubations were etiocholanolone, testosterone, and androsterone. Testosterone was converted mainly to etiocholanolone and androstenedione, and only small quantities of 11 beta-hydroxytestosterone, 11-ketotestosterone, and 11-ketoandrostenedione were the metabolites found in 11 beta-hydroxyandrostenedione incubation. These results demonstrated the presence of the enzymes 5 alpha- and 5 beta-reductases and 3 alpha-, 11 beta-, 17 beta-, and 20 beta-hydroxysteroid dehydrogenases in the skin. From enzymehistochemical results it appeared that the steroid conversions take place in the epithelial cells. Moreover, the presence of UDP-glucose dehydrogenase, an enzyme involved in the synthesis of glucuronic acid, in these cells indicates the possibility of steroid glucuronide formation. Indeed significant amounts of water-soluble steroid conjugates, particularly 5 beta-dihydrotestosterone- and testosterone-glucuronide, were found in the incubations with androstenedione and testosterone, indicating the presence of the UDP-glucuronosyl transferase in the catfish skin. In the light of these results, a role of the skin of African catfish in the production of semiochemicals having pheromonal properties is discussed.
mesh_terms: D019326:17-alpha-Hydroxyprogesterone; D000735:Androstenedione / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D002397:Catfishes / Q000378:metabolism*; D003687:Dehydroepiandrosterone / Q000378:metabolism; D005965:Glucuronates / Q000378:metabolism; D006908:Hydroxyprogesterones / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D011284:Pregnenolone / Q000378:metabolism; D012867:Skin / Q000201:enzymology / Q000378:metabolism*; D013256:Steroids / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism; D014316:Tritium
chemical_list: D005965:Glucuronates; D006908:Hydroxyprogesterones; D013256:Steroids; D014316:Tritium; D013739:Testosterone; D000735:Androstenedione; D003687:Dehydroepiandrosterone; C003582:11-hydroxyandrostenedione; D019326:17-alpha-Hydroxyprogesterone; D011284:Pregnenolone