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 μl, 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 histamine-induced local paw edema. Moreover, histamine H1 receptors function may be affected by crocin.