Anti-diarrheal effect of water extract of Evodiae fructus in mice

Our previous study showed that Evodiae fructus (the dried, unripe fruit of Evodia rutaecarpa) has an inhibitory effect on the intestinal transit (anti -transit effect) in mice. In the present study, a water extract of Evodiae fructus was used to examine its effect on castor oil-induced diarrhea and t o compare with its anti-transit effect in mice. The results indicated that Evodiae fructus had both anti-transit and anti-diarrheal effects with compa rable ID50 (the dose for 50% inhibition) values of 54 +/- 7 and 76 +/- 17 m g/kg. The time-courses of Evodiae fructus pretreatment for both anti-transi t and anti-diarrheal effects were very similar. Because no significant infl uences of both nitric oxide (NO) precursor L-arginine (600 mg/kg, i.p.) and NO synthase inhibitor N-G-nitro-L-arginine methyl ester (25 mg/kg, i.p.) p retreatment, the NO system was not involved in both the anti-transit and an ti-diarrheal effects of Evodiae fructus. Like Evodiae fructus, a muscarinic acetylcholine receptor antagonist atropine inhibited castor oil-induced in crease in fecal weight and loss of body weight. However, the potencies or t ime-courses of atropine pretreatment for both anti-transit and anti-diarrhe al effects were different. Furthermore, the anti-diarrheal effect of atropi ne was independent of its anti-transit effect at the lower dose (0.5 mg/kg, i.p.). Therefore, the action of Evodiae fructus appeared to be something d ifferent from atropine, suggesting that an action other than the anti-musca rinic action, as previously proposed for Evodiae fructus, may be involved. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.