ABSTRACT
The antidepressant effect of Sho-ju-sen, a Japanese herbal medicine composed of extracts of three herbs; kumazasa leaf (Sasa Kurinensis Makino et Sibata), Japanese red pine leaf (Pinus densiflora Sieb. et Zucc) and ginseng radix (Panax ginseng C.A. Meyer), was assessed using a learned helplessness model in mice. The learned helplessness was produced by presenting 120 unavoidable/inescapable shocks for 3 days to the mouse in a shuttle box, and the avoidance training was carried out on day 4. Compared with the control group given tap water, free consumption of Sho-ju-sen (1%, 3% and 10%) for 21 days resulted in a significant amelioration of the response rate at 1% and 3%, and both the response rate and % avoidance at 10%. Although Sho-ju-sen (10%) caused no significant effect following the 7-day intake, it ameliorated the response rate following the 14-day intake. The extract of Japanese red pine leaf, but not kumazasa leaf or ginseng radix, mildly improved the response rate. Learned helplessness was significantly and dose-dependently reduced by imipramine (10 and 30 mg/kg i.p.), while only mildly by diazepam (1 mg/kg p.o.). These results suggest that a long-term consumption of Sho-ju-sen is effective for the amelioration of depression, and the effectiveness is derived mainly from the extract of Japanese red pine leaf.