The ex vivo effect of the herbal medicine sho-saiko-to on histamine release from rat mast cells

Abstract

A traditional Japanese herbal medicine, Shosaiko-to (SST), has been used orally to treat several chronic diseases. Since these have included allergic rhinitis and bronchial asthma, we investigated the effect of SST on histamine release and the intracellular Ca2+ response in mast cells ex vivo. A single dose of 1.0 g/kg SST was administered orally to immunized rats 2-12 h before death. Mast cells were then separated from peritoneal lavages and stimulated with antigen. SST at 3 h after oral administration most significantly inhibited histamine release. This inhibitory effect was dose-dependent and was weaker than that of tranilast. In contrast, SST at 3 h had no effect on the antigen-induced Ca2+ response of the mast cells and failed to inhibit compound 48/80-induced histamine release. Our findings show that SST indeed has an active anti-allergic effect. We suggest that SST inhibits IgE receptor-associated protein phosphorylation in the histamine release pathway.