Antipruritic effects of Sophora flavescens on acute and chronic itch-related responses in mice.

To find new antipruritic herbal medicines for pruritus, we screened the methanol extracts of seven herbal medicines which have been used to treat dermatologic diseases, testing them on mouse models of acute and chronic itch. When administrated perorally (p.o.) at a dose of 200 mg/kg, methanol extracts of Sophora flavescens and Cnidium monnieri, but not the others, significantly inhibited a serotonin (5-HT)-induced itch-related response (scratching) and the spontaneous scratching of NC mice, a mouse model of atopic dermatitis. The inhibitory effect of Sophora flavescens was stronger than that of Cnidium monnieri. The methanol extract from Sophora flavescens (50-200 mg/kg) inhibited 5-HT-induced scratching in a dose-dependent manner, without any effects on the locomotor activity. These results suggest that Sophora flavescens and its constituents widely affect acute and chronic pruritus, and are possible as new antipruritic agents.