Cimetidine Inhibits the Histamine-Induced Prolactin Release in Male Rats 1

Abstract

Summary

The specificity and mechanisms through which HA alters basal PR1 release were evaluated. Rats bearing atrial catheters were given icv infusions of histamine dihydrochloride or saline. Blood samples for PRL and LH were drawn before and at 15, 30, 45, and 60 min after infusion. Similar groups of animals were pretreated with icv infusions of diphenhydramine, cimetidine, atropine, or methysergide prior to icv HA. Animals given icv HA (90 μg) demonstrated at least a twofold rise in PRL at 15 min which fell to baseline levels at 45 min. Pretreatment with cimetidine, but not other agents, significantly inhibited the HA-induced rise in PRL. Serum LH was basically unaltered by these treatments. Histamine appears to be a specific stimulus to PRL release. This stimulatory effect of HA is inhibited by cimetidine, an H₂ receptor blocker, but not by H₁ receptor, cholinergic or serotoninergic antagonists.