RESUMO
Beta-endorphin (beta-ED) levels were evaluated in blood and seminal plasma of men with infertility due to varicocele, obstructive and nonobstructive azoospermia, and idiopathic oligoasthenospermia. The relation of this opiate to serum levels of gonadotropins, prolactin, testosterone, androstenedione, and dehydroepiandrosterone sulfate has also been investigated. beta-ED levels in seminal plasma were significantly higher than in blood plasma (p less than 0.001) in all persons studied. No statistically significant differences were found for beta-ED concentrations in semen or blood among any of the infertility situations studied. Nor were significant correlations observed between the concentration of this opiate and that of gonadotropins, prolactin, and androgens. The measurement of beta-ED in semen has little value in the differential diagnosis of male infertility. Nonetheless, its presence in high levels in semen must have some unknown function. Possibly, it comes from the various sites of the male reproductive tract, since no significant differences were found between obstructive and nonobstructive azoospermias.