抄録
Morphine is known to release histamine from mast cells. It is also known that histamine receptors mediate some of morphine''s effects on the central nervous system. The contribution of H1-and H2-receptors to the effect of morphine on maximal electroconvulsive shock in mice was investigated in the present experiments. Morphine showed a dose-dependent anticonvulsive effect, but produced spontaneous clonic convulsions at higher doses (100 mg/kg, i.p.). The anticonvulsive effect of morphine (1 mg/kg, i.p.) was antagonized by histamine H1-receptor antagonists, dimethindene (0.1 mg/kg, i.p.), promethazine (0.4 mg/kg, i.p.) and pheniramine (30 mg/kg, i.p.), and naloxone (10 mg/kg, i.p.), but not by the H2-receptor antagonist ranitidine (10-50 μg, i.c.v.). These results show that morphine has an anticonvulsive effect via histamine H1-receptors against maximal electroconvulsive shock in mice.
