[Stimulation of prolactin secretion by vasoactive intestinal peptide]

Dopamine has already been recognized as an inhibiting factor of prolactin. On the other hand, the stimulators of prolactin are still judged diversely at the moment. In addition to hypothalamic TRH, serotonine as well as endogenous opiates and VIP are under discussion. The object of our studies was testing the function of VIP in directing prolactin secretion on three different groups of patients: 1. hyperprolactinaemic women of WHO-group VI; 2. patients who had undergone a TRH-test along with an endocrine check-up; 3. post partum in childbed. The determination was made from analyzing peripheral blood by radioimmunoassay. In 20 amenorrhoeic patients of WHO-group VI, their prolactin and VIP levels were determined between 8 and 10 a. m. Only 4 patients showed a VIP-concentration below 20 pg/ml (which represents the limit of detectability). The other 16 patients showed an increased concentration of VIP. In 15 cases there was an obvious correlation of VIP and prolactin concentrations according to the linear regression. In the course of a TRH-test to 20 and 40 minutes after initial blood examination prolactin and VIP were again determined. After 20 minutes all patients showed a threefold increase of the initial prolactin value. On the other hand, VIP increased in 3 cases only. Apart from all those patients who wanted to become pregnant, these three women--being postmenopausal--showed increased initial values already in the unstimulated condition. The third group of patients consisted of 26 women in childbed. Their prolactin and VIP were determined between the second and eight day post partum.(ABSTRACT TRUNCATED AT 250 WORDS)