Spasmolytic activity of Aquilariae Lignum Resinatum extract on gastrointestinal motility involves muscarinic receptors, calcium channels and NO release.

CONTEXT

Aquilariae Lignum Resinatum (ALR), the dry rhizome of Aquilaria agallocha R. (Thymelaeaeeae), has been widely used to treat emesis, stomachache and gastrointestinal dysfunction.

OBJECTIVE

This study evaluates the effects of ALR methanol extract on gastrointestinal motility (GIM) and possible mechanisms of the action involved.

MATERIALS AND METHODS

In vivo, the study evaluated the effects of ALR (200-800 mg/kg) on gastric emptying and small intestinal motility in normal and neostigmine-induced adult KM mice. The in vitro effects of ALR (0.2-1.6 mg/mL) on GIM were performed on isolated jejunum of Wistar rats, pretreated with acetylcholine (ACh), KCl, CaCl, and pre-incubation with l-NAME (a selective inhibitor of the nitric oxide synthase).

RESULTS

In vivo, ALR (800 mg/kg) decreased gastric emptying (70.82 ± 9.81%, p < 0.01, compared with neostigmine group 91.40 ± 7.81%), small intestinal transit (42.82 ± 3.82%, p < 0.01, compared with neostigmine group 85.53 ± 5.57%). In vitro, ALR concentration dependently decreased the contractions induced by ACh (10 M) and KCl (60 mM) with respective EC values of 0.35 and 0.32 mg/mL. The Ca concentration-response curves were shifted by ALR to the right, similar to that caused by verapamil (the positive). The spasmolytic activity of ALR was inhibited by pre-incubation with l-NAME.

DISCUSSION AND CONCLUSIONS

ALR played a spasmolytic role in GIM, which is probably mediated through inhibition of muscarinic receptors, blockade of Ca influx and NO release. This is the first study presenting a comprehensive description of the effects of ALR on GIM.