Investigations on the influence of prolactin suppression on reproductive function in bulls

Evaluation of semen parameters in man with hyperprolactinemia induced by metoclopramide

Hyperprolactinemia in man decreases libido and potency, but the few reports concerning its influence on spermatogenesis are contradictory. The aim of this study was to evaluate the effect of induced hyperprolactimemia on semen parameters. A total of 15 potentially fertile male volunteers, aged 28.2 +/- 4.3 years, were given 10 mg metoclopramide three times daily for 12 weeks. Serum and seminal plasma prolactin levels and semen parameters were determined before and 4, 8, and 12 weeks following initiation of metoclopramide administration. A fivefold increase of serum prolactin levels was observed, semen volume and abnormal sperm forms decreased, while spermatozoa velocity increased. On the contrary, no influence was noted on the number of spermatozoa per milliliter, the total number of spermatozoa, the percentage of motile spermatozoa, or the index of motility. Hyperprolactinemia seems to improve spermatozoal velocity and morphology, although direct effect of metoclopramide on these parameters cannot be excluded.

Prolactin and male reproduction

Elevated levels of prolactin(PRL) are associated with gonadal dysfunction in men and women, but the relationship between PRL levels and gonadal activity is best defined in women. The purpose of this review is to summarize and discuss the influence of PRL on the male reproductive function in normaprolactinemia and to describe the clinical, diagnostic, and therapeutic aspects of the male hyperprolactinemia syndrome as related to sexual dysfunction and infertility.