Anti-inflammatory effect of intraventricularly administered histamine in rats

Intracerebroventricularly (icv) administered histamine (5, 10 and 20 micrograms) produced a dose-related anti-inflammatory effect against carrageenin-induced pedal edema in rats. The effect of histamine was mimicked by the H1 receptor agonist, 2-methylhistamine, but not by the H2 receptor agonist, 4-methylhistamine. The anti-inflammatory effect of centrally administered histamine was antagonised by mepyramine, a H1 receptor antagonist, but not by cimetidine, a H2 receptor antagonist. The anti-inflammatory effect of icv histamine was inhibited in bilaterally adrenalectomised rats but was unaffected by peripheral chemical sympathectomy induced by 6-hydroxydopamine.