Effect of Japanese Angelica Root Extract on Pentobarbital-Induced Sleep in Group-Housed and Socially Isolated Mice: Evidence for the Central Action

Abstract

We investigated the effect of the aqueous extract of Japanese angelica root (JAR) on pentobarbital (PB) sleep in group-housed and socially isolated mice. The JAR extract (1.25-2.5 g/kg, p.o.) dose-dependently reversed the decrease in PB sleep caused by isolation stress without affecting PB sleep in group-housed mice. The JAR extract (2.5 g/kg, p.o.) also antagonized the decrease in PB sleep caused by the α2-adrenoceptor antagonists yohimbine and idazoxan (1 mg/kg, i.p.) and the α1-adrenoceptor agonist methoxamine (200 nmol, i.c.v.) in group-housed mice. These results suggest that the JAR extract reverses changes in the arousal level caused by isolation stress and the activation of central noradrenergic systems.