Antipruritic Effects and Primary Mechanism of Osthole

OBJECTIVE:To study antipruritic effects and mechanism of osthole. METHODS:The histamine-dependent and independent itch model was established by intradermal injection of histamine 10 μl or chloroquine on the shaved cheek of mice,respectively. The model mice were randomly divided into normal control group(constant volume 0.2% CMC-Na solution) model(constant volume 0.2% CMC-Na solution)group,positive control(histamine 1.2 mg/kg or chloroquine 0.08 mg/kg) groupand osthole high-dose,medium-dose and low-dose(40、20、10 mg/kg)groups. The itch-related behavior was observed,and the pathomorphological changes of the cheek skin were observed by microscope. RESULTS:Compared with normal control group,the times of scratching increased in model group;there was statistical significance(P0.01). Compared with the histamine-dependent itch model group,the times of scratching decreased in osthole high-dose,medium-dose and low-dose groups;there was statistical significance(P0.01,P0.05). Compared with the histamine-independent itch model group,the times of scratching decreased in osthole high-dose groups;there was statistical significance(P0.05).The times of scratching reached the peak in first 5 min after injection of chloroquine and then decreased gradually. The time interval of chloroquine-induced scratching times had no change in osthole groups. But no obvious pathomorphologic changes of the cheek skin were observed in mice. CONCLUSIONS:Osthole can improve histamine-dependent and independent itch,and osthole can better relieve histamine-dependent itch,which is possibly related to the suppression of histamine.