Developmental Regulation of the Inhibitory Effect of Dopamine on Prolactin Release in the Preterm Neonate

Abstract

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 secretion by reaching the pituitary via the portal circulation, and the hypolactotropic effect of dopamine infusion has been documented in all age groups in humans. However, the maturation of lactotroph sensitivity to dopaminergic inhibition has not been studied. Therefore, we followed the changes in serum prolactin concentrations before, during, and after dopamine infusion in 19 sick preterm infants with a mean gestational age of 30.6 ± 0.6 weeks during the first 3 days of life, and examined the relationship of the hypolactotropic effect of dopamine to gestational 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 µg/l (p < 0.05) with a return of the serum prolactin concentration to the pretreatment level 2–6 h after discontinuation of drug administration (98.3 ± 11.7 µg/l, p < 0.05). However, simple regression analysis of the individual data revealed that the magnitude of the dopamine-induced decrease in serum prolactin was significantly influenced by gestational age (p = 0.006) and birthweight (p = 0.037). Thus, our findings provide evidence for the maturation of pituitary lactotroph sensitivity to dopaminergic inhibition in the preterm human neonate.

Dopamine Administration in Very Low Birth Weight Preterm Infants:Emerging Issues on Endocrine Effects

“…Such suppression is rapidly reversible after dopamine discontinuation with hormonal rebound starting 20 minutes after drug withdrawal and tentimes increase in serum PRL occurring 2-24 hours later, according to different authors [32,260]. In a more recent study [262] neonates with mean GA of about 30 weeks, respond to dopamine administration with PRL suppression of 35% and return to basal values within 2-6 hours after withdrawal, confirming the previous results. In such population, however, dopamine-induced PRL suppression appear significantly related to GA and birthweight with milder inhibition of PRL secretion in infants with lower GA and birthweight, suggesting still incomplete maturation of dopaminergic inhibition of PRL secretion in preterm infants.…”

“…First, term neonates and VLBW infants both present with physiological hyperprolactinemia respect to the following ages [80,[213][214][215] and dopamine-induced PRL suppression is less consistent in neonates of lower GA and birthweight, with evidence of incomplete maturation of inhibiting dopaminergic system only after 30 weeks of GA [262]. Second, all the studies on hormonal arrangement during and after dopamine treatment in preterm infants, with no exception, demonstrated a rapid reversal after dopamine withdrawal, becoming apparent from 20 minutes to 1 day after the interruption, depending on the different sampling timings used by different authors [32,80,203,262]. In our recent study [80] blood samples were taken every 24 hours after dopamine discontinuation and hormonal rebound was observed from the first day after withdrawal.…”

“…Dopamine-induced PRL suppression was widely documented over the past 20 years in adults, children and neonates [32,80,202,208,[260][261][262][263]. As far as now, few evidences exist for preterm newborns, especially for VLBW infants, and only recently the eventual PRL suppression in this population assumed broadening relevance [80].…”

T1 Signal Intensity and Height of the Anterior Pituitary in Neonates: Correlation with Postnatal Time

“…Seri et al 22 studied serum prolactin concentrations before, during, and after dopamine infusion in 19 preterm infants during 3 days and revealed that dopamine therapy resulted in a decrease in mean serum prolactin concentration with a return to the pretreatment level at 2-6 hours after the discontinuation of drug administration. In the present study, the time interval from the termination of dopamine infusion to the MR examination was at least 37 days.…”

Dopamine Infusion and Anterior Pituitary Gland Function in Very Low Birth Weight Infants

“…Exogenous dopamine exerts an inhibitory effect on the physiologic hyperprolactinemia of the sick preterm neonate [14,17,18] , with a return of the serum concentration to the pre-treatment level a few hours after discontinuation of drug administration. However, the magnitude of the dopamine-induced decrease in serum PRL was less evident in newborns with lower GA and birthweight [19] .…”