Immunoreactive β-endorphin in human seminal plasma

Abstract

Seminal plasma beta-endorphin (β-EP) levels were determined by radioimmunoassay in 119 semen samples collected from fertile, infertile and healthy single young men without previously proven fertility histories. There were considerable amounts of β-EP in human seminal plasma, although the mean levels were not significantly different in the three groups. No significant correlations were found between the seminal plasma β-EP levels and individual parameters of general spermatozoal characteristics and in vitro spermatozoal fertilizing capacity. In fertile men, the levels of β-EP, FSH and LH in seminal plasma were significantly higher, whereas levels of T were significantly lower than those in serum. No significant correlations were observed between β-EP and other reproductive hormones in seminal plasma or serum. These findings confirm the presence of β-EP in seminal plasma and its local production is implicated. Whether there is a potential function of β-EP in semen on spermatozoal capacitation and fertilization in vivo, however, cannot be inferred from the present study.