Effects of perinatal administration of haloperidol on GH pituitary contents and serum levels during the first postnatal month.

Perinatal dopaminergic blockade with haloperidol caused PRL increases in rat pituitary gland and serum which persisted during the first postnatal month. However the effects of dopamine on the synthesis and secretion of GH at these early ages are unknown. With the aim of investigating the effects of this blockade on postnatal GH secretion, haloperidol (1 mg/kg i.p.) was injected daily to pregnant rats from gestational day 16 until delivery and to pups from untreated mothers between postnatal days 2-6. GH pituitary contents and serum levels were measured weekly by RIA during the first postnatal month. The results showed that haloperidol induced a long-term increase in GH pituitary contents as well as a transient increase in serum levels. The results in serum are similar to those from human neonates indicating that dopamine plays a more important role as controller of the GH secretion in newborns than in adults.