Seasonal changes in steroid metabolism in the male reproductive organ-system of the African catfish, Clarias gariepinus

Abstract

In testes, the capacity to form progestins, androgens, especially ll-oxygenated ones, and steroid glucuronides increased enormously in the periods of full spermatogenesis and breediig, with 5#?-pregnane-3a,17a,20a-triol and 5fi-pregnane-3a,17t-diol-20-one glucuronide as the main polar products. In the same periods, seminal vesicles are able to form ll-oxygenated androgens from[ 3H] -androstenedione and show an increased capacity to form testosterone. Their ability to produce testosterone glucuronide is strongly enhanced in the period of full spermatogenesis and further increases in the breeding period. In this latter period, the capacity to form 5/$androstane3a,l7cr-diol glucuronide is also stimulated. The function of the main steroids and steroid glucuronides is discussed, with special reference to the water-soluble compounds that may serve as sex pheromones.

Gas chromatographic-mass spectrometric analysis of steroids and steroid glucuronides in the seminal vesicle fluid of the African catfish, Clarias gariepinus

“…SP-Androstane-3@,17P-diol was detectable only as free steroid, while Sp-dihydrostestosterone and SP-androstane-3or, 11 P-diol-17-one could no be demonstrated at all, although these steroids were present after in vitro incubations of seminal vesicle tissue Schoonen et al, 1987b;Resink et al, 1987a).…”

“…The results of in vitro incubation studies indicate that the seminal vesicle is capable of synthesizing various steroids and at least six different, steroid glucuronides ( Fig. 9) (Schoonen and, Laml bert, 1986;Schoonen et al, 198%, 6;. Resink et al, 1987a).…”

Internal and external factors controlling reproduction in the African catfish,Clarias gariepinus

“…Seminal vesicle fluid elicited a dose-dependent attraction when added to the aquarium water of ovulated females. On the other hand, a high dose induced an avoidance reaction (Resink et al, 1987 a).…”

“…Comparing the capacity of ovarian tissue to metabolise prcgnenolone and androstenedione, Schoonen et al (1987 d) found that during the breeding period before as well immediately after spawning the ovaries can synthesis estradiol-1713, estrone and sevcral progestines and androgens, including 5[j-reduced C2 1 -and C19-steroids. Testosterone and most of the 50-reduced products were also identified in a conjugatcd form as steroid glucuronides.…”

The seminal vesicle as source of sex attracting substances in the African catfish, Clarias gariepinus

“…These conjugates may be involved in reproduction, since the capacity to form them in feral African catfish is markedly enhanced during the breeding season, both in testes and in the seminal vesicle (Resink et al, 1987b); an additional increase is observed in the latter organ during actual spawning (Resink et al, 1987a). The latter phenomenon is accompanied by a rise of circulating gonadotropin.…”