Document Detail

Androgen-induced changes in Leydig cell ultrastructure and steroidogenesis in juvenile African catfish, Clarias gariepinus.
MedLine Citation:
PMID:  10470499     Owner:  NLM     Status:  MEDLINE    
The present report focuses on the mechanism(s) involved in the steroid-induced decrease of androgen production in immature African catfish testes that was observed in previous studies. Juvenile animals were implanted with Silastic pellets containing different 11-oxygenated androgens (11-ketotestosterone, KT; 11 beta-hydroxyandrostenedione, OHA; 11-ketoandrostenedione, KA), testosterone (T) or estradiol-17 beta (E2). Control groups received steroid-free pellets. Two weeks later, testis tissue fragments were either incubated with increasing concentrations of catfish luteinizing hormone (LH), or incubated with [3H]-pregnenolone ([3H]-P5) or [3H]-androstenedione ([3H]-A). Tissue fragments were also prepared for the quantitative assessment of Leydig cell morphology. Most of the parameters studied were not affected significantly by implantation of E2. Implantation of all androgens inhibited both the basal and the LH-stimulated androgen secretory capacity in vitro. This was associated with a reduced size of the Leydig cells and loss of half of their mitochondria. The studies on the metabolism of tritiated steroid hormones indicated that steroidogenic steps prior to 11 beta-hydroxylation, probably C17-20 lyase activity, were affected by all androgens. Although the effects of 11-oxygenated androgens and T on Leydig cells were mostly similar, previous work showed that only the 11-oxygenated androgens stimulated spermatogenesis, suggesting that distinct mechanisms of action are used by 11-oxygenated androgens and T. These mechanisms, however, seem to merge on the same target(s) to impair Leydig cell androgen production. Such a negative feedback mechanism may be of relevance in the context of the decline in androgen secretion per milligram testis tissue that accompanies the first wave of spermatogenesis in pubertal African catfish.
J E Cavaco; B van Blijswijk; J F Leatherland; H J Goos; R W Schulz
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Cell and tissue research     Volume:  297     ISSN:  0302-766X     ISO Abbreviation:  Cell Tissue Res.     Publication Date:  1999 Aug 
Date Detail:
Created Date:  1999-10-13     Completed Date:  1999-10-13     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0417625     Medline TA:  Cell Tissue Res     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  291-9     Citation Subset:  IM    
Research Group for Comparative Endocrinology, Faculty of Biology, Utrecht University, The Netherlands.
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MeSH Terms
Analysis of Variance
Androgens / pharmacology*
Androstenedione / analogs & derivatives,  pharmacology,  secretion
Catfishes / anatomy & histology,  metabolism*
Drug Implants
Estradiol / pharmacology
Leydig Cells / drug effects*,  ultrastructure
Secretory Rate / drug effects
Steroids / biosynthesis*
Stimulation, Chemical
Testosterone / analogs & derivatives,  pharmacology
Reg. No./Substance:
0/Androgens; 0/Drug Implants; 0/Steroids; 50-28-2/Estradiol; 53187-98-7/11-ketotestosterone; 564-32-9/11-hydroxyandrostenedione; 58-22-0/Testosterone; 63-05-8/Androstenedione

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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