Steroids in semen, their role in spermatogenesis, and the possible impact of endocrine disruptors.

The data on hormonal steroids in the human seminal plasma and their role in spermatogenesis are summarized. The seminal steroid levels need not correlate with the blood plasma levels. The recent reports showed that androgen, especially dihydrotestosterone, and the estrogen levels in the seminal fluid may be used as the markers of spermatogenesis impairment. The estradiol concentration in the seminal plasma was higher than in the blood plasma, and its levels were significantly increased in men with impaired spermatogenesis. A good indicator for predicting the normal spermatogenesis, therefore, seems to be the testosterone/estradiol ratio. The seminal plasma also contains significant amounts of cortisol, which influences the androgen biosynthesis through its receptors in the Leydig cells. The local balance between cortisol and inactive cortisone is regulated by 11β-hydroxysteroid dehydrogenase, the activity of which may be affected by the environmental chemicals acting as the endocrine disruptors (EDCs). These compounds are believed to participate in worsening the semen quality - the sperm count, motility, and morphology, as witnessed in the recent last decades. As to the steroids' role in the testis, the EDCs may act as antiandrogens by inhibiting the enzymes of testosterone biosynthesis, as the agonists or antagonists through their interaction with the steroid hormone receptors, or at the hypothalamic-pituitary-gonadal axis. Surprisingly, though the EDCs affect the steroid action in the testis, there is no report of a direct association between the concentrations of steroids and the EDCs in the seminal fluid. Therefore, measuring the steroids in the semen, along with the various EDCs, could help us better understand the role of the EDCs in the male reproduction.