Abstract
Abstract
To study the possible involvement of hypothalamic vasoactive intestinal polypeptide (VIP) in regulating the secretion of prolactin (PRL), the effect of anti-VIP rabbit serum on serotonin (5-HT)-induced PRL release was examined in urethane-anesthetized male rats. Anti-VIP serum (AVS) or normal rabbit serum (NRS) was infused into a single hypophysial portal vessel of the rat for 40 min at a rate of 2 μl/min with the aid of a fine glass cannula and 5-HT was injected into a lateral ventricle 10 min after the start of the infusion. Intraventricular injection of 5-HT (10 μg/rat) caused an increase in plasma PRL levels in control animals infused with NRS and 5-HT-induced PRL release was blunted in animals infused with AVS (mean±SE peak plasma PRL: 118.9±19.8 ng/ml vs 54.7±16.2 ng/ml, p<0.05). These findings suggest that the secretion of PRL induced by 5-HT is mediated, at least in part, by hypothalamic VIP release into the hypophysial portal blood in the rat.
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