An interaction of histamine H2-receptor antagonists with the noradrenergic system in rat brain.

Intraventricular administration of 50 microgram of burimamide or 250 microgram of either metiamide or cimetidine decreased the NA concentration in rat hypothalamus by nearly 30%. Cimetidine did not significantly influence either DA or DOPAC levels in striatum. Cimetidine and metiamide significantly potentiated locomotor activity of tranylcypromine-treated rats and this effect was antagonized by phentolamine. It is concluded that the three histamine H2-receptor antagonists released NA in rat brain.