Effects of Sho-saiko-to, San'o-shashin-to and Scutellariae Radix on intracellular Ca2+ mobilization in C6 rat glioma cells

Abstract

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 Ca2+ mobilization. C6 rat glioma cells expressed H1-histamine, muscarinic cholinergic and adrenergic α1- receptors, stimulation of which resulted in phosphoinositide hydrolysis and increase in intracellular Ca2+ concentrations ([Ca2+](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 GEORGI) inhibited histamine (100 μM)-induced increase in [Ca2+](i) in a concentration-dependent manner. The water extract of Scutellariae Radix potently decreased [Ca2+](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 inhibition of the increase in [Ca2+](i). These results suggest that Sho-saiko-to, San'o-shashin-to and Scutellariae Radix inhibit Ca2+ mobilization mediated via an inhibition of phospholipase C. The inhibitory effect may be important in interpreting the pharmacological actions of above Kampo medicines.