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  • 1
    Electronic Resource
    Electronic Resource
    Pubertal development of male African catfish,Clarias gariepinus. In vitro steroidogenesis by testis and interrenal tissue and plasma levels of sexual steroids (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 129-138 
    Details
    ISSN: 1573-5168
    Keywords: Clarias gariepinus ; African catfish ; teleost fish ; puberty ; spermatogenesis ; steroidogenesis ; testis ; interrenal tissue ; androgen blood levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In fish, sex steroids initiate and/or accelerate the maturation of the brain-pituitary-gonad axis. In order to obtain information on the steroid milieu during the pubertal development of male African catfish, we have monitored the conversion of [3H]-pregnenolone and [3H]-androstenedione by testis and [3H]-pregnenolone by interrenal tissue fragmentsin vitro. Pubertal development occurs between two and six months of age. Testicular development proceeds through four main stages that are characterised histologically by the presence of spermatogonia (stage I), spermatogonia and spermatocytes (stage II), spermatogonia, spermatocytes and spermatids (stage III), and all germ cells including spermatozoa (stage IV). 11β-Hydroxyandrostenedione and cortisol were the main products of testes and interrenal tissue, respectively, in all stages of the pubertal development; a change in the steroidogenic pattern was not observed during this period. The interrenal tissue displayed no significant conversion of [3H]-pregnenolone to 11-oxygenated androgens. Blood plasma was analyzed for the presence of five androgens; testosterone, 11β-hydroxytestosterone, 11β-hydroxyandrostenedione, androstenetrione, and 11-ketotestosterone. 11-Ketotestosterone was the quantitatively dominating androgen in the circulation at all stages of development, which was more pronounced in stages III and IV. The obvious differences between thein vitro andin vivo results, namely 11β-hydroxyandrostenedione being the main testicular productvs. 11-ketotestosterone dominating in the blood, may indicate that 11β-hydroxyandrostenedione is converted to 11-ketotestosterone at extratesticular sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004670
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  • 2
    Electronic Resource
    Electronic Resource
    Steroid hormone secretion by testicular tissue from African catfish, Clarias gariepinus, in primary culture: identification and quantification by gas chromatography — mass spectrometry (1993)
    Springer
    Fish physiology and biochemistry 12 (1993), S. 21-30 
    Details
    ISSN: 1573-5168
    Keywords: gas chromatography-mass spectrometry ; teleosts ; testis ; steroids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004319
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    Paper (German National Licenses)
    Fulltext
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