Abstract
Summary
Metoclopramide, a procainam-ide derivative known to raise serum prolac-tin (PRL) levels in intact humans, produced a significant increase in serum PRL when administered intraperitoneally to male rats. In contrast, direct application of metoclopramide to the isolated rat pituitary in a perifusion system did not increase prolactin release in vitro. In this system, dopamine inhibited prolactin secretion. Perifusion with both metoclopramide and dopamine blocked the inhibitory effect of dopamine on prolactin release. This suggests that metoclopramide promotes PRL secretion by antagonism of dopamine-mediated CNS-de-pendent mechanisms. Although metoclopramide had no effect on serum growth hormone in the intact rat, the drug antagonized the growth hormone-inhibiting action of dopamine in vitro.
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