STEROID-HORMONE SECRETION BY TESTICULAR TISSUE FROM AFRICAN CATFISH, CLARIAS-GARIEPINUS, IN PRIMARY CULTURE - IDENTIFICATION AND QUANTIFICATION BY GAS-CHROMATOGRAPHY - MASS-SPECTROMETRY

With the final aim of identifying the testicular steroids involved in the feedback mechanism of the hypothalamus-pituitary-gonad axis, stero id secretion by the testis of African catfish, Clarias gariepinus, was studied in vitro, by means of gas chromatography followed by mass spe ctrometry. Testicular fragments of sexually mature catfish raised in c aptivity were incubated in L-15 medium with and without catfish pituit ary extract (cfPE). Without adding cfPE, 22 steroids could be identifi ed, amongst which 11beta-hydroxyandrostenedione, 11beta-hydroxytestost erone, 11-ketotestosterone and 11-ketoandrostenedione were dominating. After incubation in the presence of cfPE, the concentrations of the f our 11-oxygenated steroids were increased about 4-fold. The amounts of pregnane derivatives in the incubation medium showed the largest incr eases in the presence of cfPE. 5beta-Pregnane-triol levels, for exampl e, were 60-fold higher than in the medium from control incubations. Th e secretion of 5alpha- and 5beta-androstanes was also stimulated by cf PE. The stimulation was not equal for all steroids, indicating that cf PE not only stimulates total steroidogenesis by increasing the availab ility of cholesterol, but also by influencing specific steroid convert ing enzyme activities.