Effects of Sho-saiko-to, San'o-shashin-to and Scutellariae Radix on Intracellular Ca2+ Mobilization in C6 Rat Glioma Cells

Glial cells are able to support neurons physically and functionally. The present study was undertaken to determine the effects of Kampo medicines on glial cell function, especially Ca mobilization. C6 rat glioma cells expressed H1-histamine, muscarinic cholinergic and adrenergic α1-receptors, simulation of which resulted in phosphoinositive hydrolysis and increase in intracellular Ca concentration ([Ca]i).The water extracts of Sho-saiko-to and San'o-shashin-to, Kampo medicines which contain Scutellariae Radix (Ogon, the root of Scutellaria baicalensis GEORI), inhibited histamine (100μM)-induced increase in [Ca]i in a concentration-dependent manner. The water extract of Scutellariae Radix potently decreased [Ca]i in a concentration-dependent manner. Sho-saiko-to, San'o-shashin-to and Scutellariae Radix significantly inhibited histamine-induced accumulation of total [3H]inositol phosphates, consistent with their inbition of the increase in [Ca]i. These results suggest that Sho-saiko-to, San'o-shashin-to and Scutellariae Radix inhibit Ca mobilization mediated via an inhibition of phospholipase C. The inhibitory effect may be important in interpreting the pharmacological actions of above Kampo medicines.