DEVELOPMENTAL REGULATION OF THE INHIBITORY EFFECT OF DOPAMINE ON PROLACTIN-RELEASE IN THE PRETERM NEONATE

The secretion and release of prolactin from the anterior pituitary is under the tonic inhibitory control of endogenous dopamine produced in the central nervous system, Exogenous dopamine inhibits prolactin secr etion by reaching the pituitary via the portal circulation, and the hy polactotropic effect of dopamine infusion has been documented in all a ge groups in humans, However, the maturation of lactotroph sensitivity to dopaminergic inhibition has not been studied, Therefore, we follow ed the changes in serum prolactin concentrations before, during, and a fter dopamine infusion in 19 sick preterm infants with a mean gestatio nal age of 30.6 +/- 0.6 weeks during the first 3 days of life, and exa mined the relationship of the hypolactotropic effect of dopamine to ge stational age and birth weight in this patient population, As expected , dopamine therapy resulted in a decrease in mean serum prolactin from 89.4 +/- 9.5 to 58.6 +/- 9.1 mu g/l (p < 0.05) with a return of the s erum prolactin concentration to the pretreatment level 2-6 h after dis continuation of drug administration (98.3 +/- 11.7 mu g/l, p < 0.05), However, simple regression analysis of the individual data revealed th at the magnitude of the dopamine-induced decrease in serum prolactin w as significantly influenced by gestational age (p = 0.006) and birthwe ight (p = 0.037), Thus, our findings provide evidence for the maturati on of pituitary lactotroph sensitivity to dopaminergic inhibition in t he preterm human neonate.