Potentiation by saiboku-to of diazepam-induced decreases in hippocampal and striatal acetylcholine release in rats

Summary Effects of saiboku-to , a traditional oriental herbal medicine, on diazepam-induced changes in cerebral acetylcholine (ACh) were investigated in rat striatum and hippocampus. Diazepam (10 mg/kg, i.p.) increased tissue concentrations of the ACh in both regions. The increase was enhanced in rats subacutely treated with saiboku-to (2.0 g/kg, p.o., once a day) for 7 days. Diazepam also decreased release levels of ACh in both regions. The release levels were further decreased in saiboku-to -treated rats. On the other hand, no significant changes in ACh synthesizing and the hydrolyzing enzyme activities in either brain region were observed in saiboku-to -, diazepam- and combination-treated rats. These results suggest that not only is the diazepam-induced increase in tissue ACh due to the inhibition of ACh release but also that saiboku-to potentiates diazepam-induced inhibition of ACh release.