Research On The Effects And Mechanisms Of Paeoniflorin And Glycyrrhizic Acid In The Regulation Of Gastrointestinal Motility

Objective To study the effects and mechanisms ofpaeoniflorin and glycyrrhizic acid in the regulation of gastrointestinal motility. Methods Rat circular gastrointestinal smooth muscle strips were obtained, and paeoniflorin and glycyrrhizic acid were administered to inhibited Ach stimulated contraction (i.e. induced relaxation). The effects were studied by recording changes in length isotoniclly via Biopac MP150 Lever Tranducer. The gastrointestinal smooth muscle strips were preteated with L-NNA(an inhibitor of NOS), SNP(NO dornor) and Atropine alone or in combination to probe the mechanisms of relaxation induced by paeoniflorin and glycyrrhizic acid. Results (l)There were spontaneous contraction in gastrointestinal smooth muscle strips in normal ststes. Their frenquency were 4.1+0.4/min in gastric antrum, 5.1 + 0. 5/min in gastric corpus, 13. 9?0. 9/min in gastric fundus, and 24. 3 + 1. 3/min in proximal jejunum. (n=9). (2)In circular smooth muscle strips ofgastric fundus, the relaxant effect was induced by paeoniflorin. The effects of relaxation increased in a concentration-dependent manner. (3)paeon if lor in-induced relaxation was abolished by NOS inhibitor L-NNA(10~SM). When L-NNA and SNP were administered, the effect of relaxtion was not affected. (4)In circular smooth muscle strips of proximal jejunum, the relaxant effect could be induced by paeoniflorin and the Paeoniflorin-induced relaxation of jejunum was associated with increases in its concentration. (5) gastric smooth muscle strips contraction were inhibited in Krebs solution of Ca2*-f ree (Ca2+ removed by EDTA). Ach stimulated strips contractions were inhibited by Atropine. Paeoniflorin and glycyrrhizic acid had a weak effect compared to Atropine. A combination of paeoniflorin and glycyrrhizic acid had synergistic action. (6)In gastric smooth muscle strips, the relaxant effect were induced by glycyrrhizic acid. (7) A distinct combination of paeoniflorin and glycyrrhizic acid(l. 2mM) had synergistic relaxant action for jejunum. Conclusions (l)Relaxant effects in gastricand intestinal smooth muscle strips were induced by paeoniflorin and glycyrrhizic acid. (2) There were synergistic relaxant action of paeoniflorin and glycyrrhizic acid. (3)Paeoniflorin-induced relaxation in smooth muscle were inhibited by NOS inhibitor L-NNA. These results suggest that NO may play an important role in the mechanisms of paeoniflorin and glycyrrhizic acid induced relaxation of smooth muscle.