Electroacupuncture Elicits Dual Effects: Stimulation of Delayed Gastric Emptying and Inhibition of Accelerated Colonic Transit Induced by Restraint Stress in Rats

Abstract

Acupuncture has been used for treating functional gastrointestinal (GI) disorders. Animal studies have demonstrated that acupuncture antagonized various stress-induced responses. We investigated the effects of electroacupuncture (EA) at ST-36 (Zusanli; lower limb) on stress-induced alteration of GI motor activities. Solid gastric emptying was significantly delayed by restraint stress (29.6±2.4%; n=7) compared to that of controls (60.0±2.5%; n=8). Delayed gastric emptying was significantly improved by EA at ST-36 (47.2±1.8%). Intracisternal (IC) injection of corticotropin releasing factor (CRF; 1 μg) delayed gastric emptying to 25.4±3.1%, which was also improved by EA at ST-36, to 53.0±7.1% (n=8). The stimulatory effect of EA on stress-induced delayed gastric emptying was abolished by atropine (17.6±1.9%) but not by guanethidine (42.2±2.3%). Colonic transit was significantly accelerated by restraint stress (GC=7.2±0.3; n=8) compared to that of controls (GC=5.2±0.2; n=8). Accelerated colonic transit was significantly reduced by EA at ST-36 (GC=4.9±0.3). IC injection of CRF accelerated colonic transit (GC=6.9±0.2), which was also normalized by EA at ST-36 (GC=4.7±0.2). The inhibitory effect of EA on stress-induced acceleration of colonic transit was not affected by guanethidine (GC=4.6±0.3). In conclusion, EA at ST-36 showed dual effects: stimulation of stress-induced delayed gastric emptying and inhibition of stress-induced acceleration of colonic transit. The stimulatory effect of EA on stress-induced delayed gastric emptying is mediated via cholinergic pathways. The inhibitory effect of EA on stress-induced acceleration of colonic transit is independent of the sympathetic pathway.