Traditional Chinese medicine Zhiqiao-Houpu herb-pair induce bidirectional effects on gastric motility in rats.

Ethnopharmacological Relevance: Zhiqiao-Houpu herb-pair (ZQHPHP), composed of Fructus Aurantii (Zhiqiao [ZQ] in Chinese) and Magnolia officinalis (Houpu [HP] in Chinese), is a traditional herbal formula that has been extensively used for treating gastrointestinal motor dysfunction. The aim of the study was to evaluate the effect and possible mechanism of ZQHPHP on gastric emptying (GE) and gastric antral smooth muscle contractility (GASMC).

Materials And Methods: This study includes four parts: (a) study of ZQHPHP's effect on GE; (b) study of ZQHPHP's effect on gastric antral smooth muscle contractility (GASMC); (c) comparing the effects of ZQHPHP, ZQ and HP on GASMC; (d) study of antagonists or agonists on ZQHPHP-induced GASMC. A test meal of Evans blue was adopted to estimate GE in rats. A polygraph was used to measure GASMC in rats.

Results: The in vivo experiments demonstrated that, at the doses of 10mg/kg bw and 20mg/kg bw, ZQHPHP could promote GE. While, at the higher dose of 30 mg/kg bw, ZQHPHP delayed the GE. From the in vitro experiments we found that ZQHPHP (3-10 μg/ml) concentration-dependently increased the mean amplitude of contractions in the antral circular strip compared to untreated controls. While, in the concentration of 30 μg/ml, ZQHPHP prohibited GASMC. Besides, atropine blocked the stimulatory effect of ZQHPHP on GASMC and norepinephrine partly prohibited the stimulatory effect of ZQHPHP on GASMC, whereas isoproterenol showed no effect. From the in vitro experiment, we also found that ZQ and HP used together can synergistically increase gut motor.

Conclusions: The experiment indicated that ZQHPHP could induce bidirectional regulation on gastric motility. ZQ and HP used together can synergistically increase gut motor at a certain dosage. Lower dosage of ZQHPHP increases gastric motility, while higher dosage produces inhibition. In addition, the improvement of gastric motility by ZQHPHP is predominantly involved with muscarinic receptors and secondarily with alpha-receptors.