Crocin alleviates the local paw edema induced by histamine in rats

Crocin, as an active constituent of saffron, has many biological functions including antioxidant and anti-inflammatory activities. The present study was aimed to investigate the effects of crocin and chlorpheniramine on local edema induced by histamine. Local edema was induced by subcutaneous injection of histamine [100 micro l, 0.1%] in ventral surface of right hind paw. The thickness of paw was measured at 1 h before and 1, 2, 3 h after injection of histamine, using a fine caliper. The number of neutrophils in paw tissue sections was counted 3 h after intraplantar injection of histamine. Intraperitoneal injection of crocin at doses of 100 and 200 mg/kg and chlorpheniramine at a dose of 10 mg/kg significantly [p<0.05] decreased both paw thickness and infiltration of neutrophils in paw tissues. In a combined treatment, intraperitoneal injection of an effective dose of crocin [100 mg/kg] with an ineffective dose of chlorpheniramine [2.5 mg/kg] produced a more documented response in comparison with crocin [100 mg/kg] and chlorpheniramine [2.5 mg/kg] used alone. The results suggested that both crocin and chlorpheniramine suppressed histamineinduced local paw edema. Moreover, histamine H1 receptors function may be affected by crocin