The anxiolytic effect of sho-ju-sen, a Japanese herbal medicine, assessed by an elevated plus-maze test in mice

Sho-ju-sen (SK), a Japanese herbal medicine with a nourishing tonic action, is composed of a water extract of Kumazasa leaves (Sasa kurinensis Makino et Sibata) (SS), and ethanol extracts of Japanese red pine needles (Pinus d ensiflora Sieb. et Zucc) (PN) and Ginseng roots (Panax ginseng C, A, Meyer) (PX) in the ratio 8:1:1, In this study, an elevated plus-maze test in mice was carried out to assess whether SK had an anxiolytic effect, No signific ant change was observed in either the plus-maze or activity test following a single administration of SK (10 and 20 mL/kg p.o,), However, mice allowed a free intake of SK (10% solution) for 5 days and longer showed a signific ant prolongation of the time spent in the open arms tan anxiolytic effect), as long as that caused by the benzodiazepine anxiolytic diazepam (1 mg/kg p.o.). SK (1%, 3% and 30% solutions for 7 days) tended to develop the anxio lytic effect, Of the constituents of SK, SS (8% solution), but not PN (1% s olution) or PX (1% solution), resulted in the anxiolytic effect. Except for a slight acceleration in the motor activity by PN (1% solution), no signif icant change in the motor activity was produced by any treatment with SK, S S of PX, The combined treatment of SK (10% solution) or SS (8% solution) wi th 1 mg/kg diazepam enhanced the anxiolytic effect. Flumazenil (0.1 mg/kg s ,c,), a benzodiazepine receptor antagonist, alone did not change the time s pent in the open arms. However, it completely reversed the anxiolytic effec t of SK, SS and diazepam, The present results suggest that: (1) long-term t reatment with SK develops an anxiolytic effect, (2) SS is the main constitu ent for the anxiolytic effect of SK, and (3) benzodiazepine receptors are i nvolved in the anxiolytic effect of SK and SS, Copyright (C) 2001 John Whey & Sons, Ltd.