The effects of crocin and safranal on the yawning induced by intracerebroventricular injection of histamine in rats

OBJECTIVE Crocin and safranal, as the major constituents of saffron, have many biological activities. This study investigated the effects of crocin and safranal on yawning response induced by intracerebroventricular (i.c.v.) injection of histamine in rats. MATERIALS AND METHODS In ketamine/xylazine-anesthetized rats, a guide cannula was implanted in the right ventricle of the brain and yawning induced by i.c.v. injection of histamine. Crocin and safranal were intraperitoneally (i.p.) injected alone and before i.c.v. injection of histamine. RESULTS Histamine at the doses of 10 and 20 µg/rat produced yawning. Mepyramine (a histamine H1 receptor antagonist) 40 µg/rat significantly (p<0.05) prevented histamine (20 µg/rat)-induced yawning. Crocin (30 mg/kg) and safranal (1 mg/kg) significantly (p<0.05) increased histamine (10 µg/rat)-induced yawning. Crocin and safranal also induced yawning when injected before mepyramine plus histamine administration. CONCLUSION The results of the present study showed a yawning-inducing effect for central histamine, which was inhibited by mepyramine. Crocin and safranal increased histamine-induced yawning, and also produced yawning when the histamine action is blocked.