Immunolocalization of Aromatase in Stallion Leydig Cells and Seminiferous Tubules

High levels of plasma estrogens constitute an endocrine peculiarity of the adult stallion. This is mostly due to testicular cytochrome P450 aromatase, the only irreversible enzyme responsible for the bioconversion of androgens into estrogens. To identify more precisely the testicular aromatase synth...

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Bibliographic Details
Published in:The journal of histochemistry and cytochemistry 2003-03, Vol.51 (3), p.311-318
Main Authors: Sipahutar, Herbert, Sourdaine, Pascal, Moslemi, Safa, Plainfosse, Bruno, Seralini, Gilles-Eric
Format: Article
Language:English
Subjects:
Age Factors
Animals
Aromatase - metabolism
Horses
Immunohistochemistry
Leydig Cells - enzymology
Leydig Cells - ultrastructure
Male
Microsomes - enzymology
Microsomes - ultrastructure
Rabbits
Seminiferous Tubules - enzymology
Seminiferous Tubules - ultrastructure
Sertoli Cells - enzymology
Sertoli Cells - ultrastructure
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Summary:High levels of plasma estrogens constitute an endocrine peculiarity of the adult stallion. This is mostly due to testicular cytochrome P450 aromatase, the only irreversible enzyme responsible for the bioconversion of androgens into estrogens. To identify more precisely the testicular aromatase synthesis sites in the stallion, testes from nine horses (2–5 years) were obtained during winter or spring. Paraplast-embedded sections were processed using rabbit anti-equine aromatase, followed by biotinylated goat anti-rabbit antibodies, and amplified with a streptavidin-peroxidase complex. Immunore-activity was detected with diaminobenzidine. Immunofluorescence detection, using fluoroisothiocyanate-conjugated goat anti-rabbit antibodies, was also applied. Specific aromatase immunoreactivity was observed intensely in Leydig cells but also for the first time, to a lesser extent, in the cytoplasm surrounding germ cells at the junction with Sertoli cells. Interestingly, the immunoreactivity in Sertoli cells appears to vary with the spermatogenic stages in the basal compartment (with spermatogonia) as well as in the adluminal one (with spermatids). Relative staining intensity in Leydig and Sertoli cells and testicular microsomal aromatase activity increased with age. The present study in stallions indicates that in addition to Leydig cells, Sertoli cells also appear to participate in estrogen synthesis, and this could play a paracrine role in the regulation of spermatogenesis.
ISSN:0022-1554
1551-5044
DOI:10.1177/002215540305100306