Prolactin (PRL) inhibiting substance in seminal plasma of infertile patients. Preliminary results.

The role of PRL in the control of the mechanisms of regulation of testicular function is still unclear. Indeed, hyperprolactinemia is usually associated with male hypofertility. Several studies have demonstrated that human seminal plasma (HSP) contains radioimmunoassayble PRL and than testis and prostate possess membrane receptors for PRL (Charreau et al. 1977; Aragona et al. 1977). Recently Demoulin and Franchimont have observed, in HSP, the presence of a substance capable of inhibiting PRL secretion by isolated rat pituitary cells (Demoulin et al. 1978). They abbreviated it SPIF (seminal plasma PRL inhibiting factor). The inhibition of PRL secretion was significant for concentrations equal to or higher than 4.2 l of HSP/ml of culture medium. This non steroidal substance is thermostable and trypsin resistant; the molecular weight is less than 10,000 Daltons. In this work, we have compared the SPIF activity with basal levels of LH, FSH, PRL, Testosterone and, after stimulation, in the serum of patients affected with various fertility problems.