Steroid hormone secretion by testicular tissue from African catfish, Clarias gariepinus, in primary culture: identification and quantification by gas chromatography — mass spectrometry

Abstract

With the final aim of identifying the testicular steroids involved in the feedback mechanism of the hypothalamus-pituitary-gonad axis, steroid secretion by the testis of African catfish, Clarias gariepinus, was studied in vitro, by means of gas chromatography followed by mass spectrometry. Testicular fragments of sexually mature catfish raised in captivity were incubated in L-15 medium with and without catfish pituitary extract (cfPE). Without adding cfPE, 22 steroids could be identified, amongst which 11β-hydroxyandrostenedione, 11β-hydroxytestosterone, 11-ketotestosterone and 11-ketoandrostenedione were dominating. After incubation in the presence of cfPE, the concentrations of the four 11-oxygenated steroids were increased about 4-fold. The amounts of pregnane derivatives in the incubation medium showed the largest increases in the presence of cfPE. 5β-Pregnane-triol levels, for example, were 60-fold higher than in the medium from control incubations. The secretion of 5α- and 5β-androstanes was also stimulated by cfPE.The stimulation was not equal for all steroids, indicating that cfPE not only stimulates total steroidogenesis by increasing the availability of cholesterol, but also by influencing specific steroid converting enzyme activities.

SEX STEROIDS AND SPERMATOGENESIS IN THE AFRICAN CATFISH (CLARIAS GARIEPINUS)

“…11b-Hydroxyandrostenedione (OHA) and cortisol are the main products of testis and inter-renal tissue, respectively, in all stages of spermatogenesis. Changes in the steroidogenic pattern during spermatogenesis are not observed, so that previous investigations in adult catfish using different methods [33,45] were confirmed for juvenile and pubertal males. In addition to OHA, the synthesis of T and KT is also demonstrated, although in small amounts only (< 5% and < 1% of OHA for T and KT, respectively; [ [10]).…”

Production of recombinant channel catfish (Ictalurus punctatus) FSH and LH in S2 Drosophila cell line and an indication of their different actions

“…The supernatants were stored at 20 8C until the secreted androgen (4-androsten-11b-ol-3, 17-dione; OHA) levels were determined by RIA as described previously (Schulz et al 1996). OHA is the quantitatively dominating androgen secreted by African catfish testis (Vermeulen et al 1993). The results are expressed as nanograms of OHA secreted per milligram of testis tissue incubated.…”

Both recombinant African catfish LH and FSH are able to activate the African catfish FSH receptor

“…The supernatants were stored at 20 C, until the secreted OHA (4-androsten-11 -ol-3,17-dione) levels were determined by RIA, as described previously (Schulz et al 1996). OHA is the quantitatively dominating androgen secreted by African catfish testis (Vermeulen et al 1993). The results are expressed as ng OHA secreted/mg testis tissue.…”