Epididymal proteins mimic the androgenic effect on zona pellucida recognition by immature hamster spermatozoa

in Reproduction
Authors:
Patricia S. Cuasnicú
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Fernanda González Echeverría
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Alejandra Piazza
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Lucrecia Piñeiro
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J. A. Blaquier
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Summary. The increase in zona pellucida binding caused by the exposure of cultured proximal corpus epididymidis to 2 μm-5α-DHT (0·87 and 4·29 spermatozoa/egg for control and 5α-DHT group respectively) was lost when 20 μm-cycloheximide was also added to the medium (0·72 spermatozoa/egg). These results were interpreted as meaning that de-novo protein synthesis was required to obtain the effect of androgens. When a fraction enriched in epididymal glycoproteins EP2–EP6 (18% total protein in epididymal cytosol and 30% in enriched fraction) and depleted of androgens (<120 pg testosterone + DHT/ml) was added to the cultured epididymal tubules, the zona pellucida-binding ability of the contained spermatozoa increased from 0·55 in controls to 2·73 spermatozoa/egg in the extract-treated group (P < 0·02). When the enriched fraction was prepared from epididymides of 30-day castrates, the stimulatory effect was lost (1·04 spermatozoa/egg). We suggest that proteins synthesized in the epididymis are required to obtain the effect of androgens and that the glycoproteins EP2–EP6 may be involved.