Alteration of free sulphydryl content of rat sperm heads by suppression of intratesticular testosterone

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Abstract
Injections (s.c.) of testosterone propionate to adult male rats at a dose of 2.5 or 10 mg/kg body weight, 3 times per wk for 7 wk, resulted in a 75% reduction in serum LH [luteinizing hormone] and > 50% reduction in intratesticular testosterone concentration, but serum FSH levels remained unchanged. The free -SH content, measured as iodo[14C]acetamide binding, increased by 70-100% in testicular sperm heads after suppression of testicular testosterone, and by 25-30% in caput epididymal sperm heads but was decreased by 70-80% in cauda epididymal sperm heads. An alteration in the oxidative state of sperm nuclear basic proteins was demonstrated, suggesting incomplete nuclear maturation. These changes may be specific for the suppression of intratesticular testosterone, thus illustrating the androgen dependency of sperm head maturation. The contrast effects noted between the iodo[14C]iodoacetamide binding by the caput and the cauda epididymal sperm heads indicate that testosterone propionate treatment may affect the mechanisms regulating the oxidation of the sulfhydryl residues in sperm heads during epididymal transit. This alteration may not directly relate to the tissue androgen concentrations.