Cholinergic involvement in the improving effects of Yoku-kan-san-ka-chimpi-hange (Yi-Gan-San-Jia-Chen-Pi-Ban-Xia) on the disruption of spatial cognition and the electroconvulsive shock-induced immobilization

We investigated the effect of Yoku-kan-san-ka-chimpi-hange (Yi-Gan-San-Jia-Chen-Pi-Ban-Xia;抑肝散加陳皮半夏) on an experimentally-induced disruption of spatial cognition using an eight arm radial maze task and the electroconvulsive shock (ECS) -induced immobilization in comparison with that of tetrahydroaminoacridine (THA) in rats. Yoku-kan-san-ka-chimpi-hange (10-100mg/kg, p.o.) improved the scopolamine (0.5mg/kg, i.p.) and the Δ^9-tetrahydrocannabinol (THC; 6mg/kg, i.p.) -induced disruption of spatial cognition in rats. THA (0.5-20mg/kg, p.o.) also improved the scopolamine-and THC-induced disruption of spatial cognition in rats. Yoku-kan-san-ka-chimpi-hange (30-100mg/kg) and THA (5mg/kg) suppressed the ECS (90mA, 0.2 s) -induced immobilization, which is a behavioral model of a disturbance of consciousness. On the other hand, Yoku-kan-san-ka-chimpi-hange had no effect on the immobility time in a rat forced swimming test, a model of depression in experimental animals. Furthermore, Yoku-kan-san-ka-chimpi-hange (10-100mg/kg, p.o.) and THA (5-20mg/kg, p.o.) enhanced oxotremorine-induced tremors in mice. These results suggest that Yoku-kan-san-ka-chimpi-hange may indirectly enhance the cholinergic neurons and also improve an experi-mentally-induced disruption of spatial cognition and consciousness.