Electroacupuncture improves restraint stress-induced delay of gastric emptying via central glutaminergic pathways in conscious rats

Acupuncture has been used for treating functional gastrointestinal (GI) disorders. Animal studies demonstrated that acupuncture improves various stress-induced physiological responses. We investigated the effects of electroacupuncture (EA) at ST-36 (Zusanli; lower limb) on stress-induced delay of gastric emptying. Solid food gastric emptying in 90 min was significantly delayed by restraint stress (27.3 ± 2.1%, n = 8), compared to that of controls (64 ± 2.1%, n = 8). Restraint stress-induced delay of gastric emptying was significantly restored by the intracisternal (IC)-injection of GABAA receptor antagonist, bicuculline methiodide (46.5 ± 3.1%; n = 6) and GABAB receptor antagonist, phaclofen (48 ± 3.3%; n = 6). Delayed gastric emptying induced by restraint stress was significantly improved by EA at ST-36 (49.7 ± 1.4%). The stimulatory effect of EA on stress-induced delay of gastric emptying was prevented by pretreatment with IC-injection of glutamate receptor antagonist, kynurenic acid (30.1 ± 2.1%). In conclusion, restraint stress-induced delay of gastric emptying is mediated via central GABAA and GABAB receptors. EA at ST-36 stimulates glutaminergic neurons in the brainstem resulting in improvement of stress-induced delay of gastric emptying.