Effects of Acupuncture on Gastric Motility in Rats

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DESCRIPTION (provided by applicant): Acupuncture has been used to treat gastrointestinal (GI) symptoms in China for more than 3,000 years. However, the mechanism of beneficial effects of acupuncture still remains unknown. Our recent studies have shown that acupuncture to the abdomen caused a transient relaxation of the stomach, while the acupuncture to the hind limb caused a transient contraction in thiobutabarbital (Inactin)-anesthetized rats. Gastric relaxations induced by acupuncture to the abdomen were abolished by guanethidine, propranolol, hexamethonium, splanchnic ganglenectomy, but not by vagotomy. In contrast, gastric contractions induced by acupuncture to the hind limb were abolished by atropine, hexamethonium and vagotomy, while splanchnic ganglenectomy and guanethidine had no effects. Both of acupuncture-induced gastric relaxations and contractions were abolished by spino-medullary transection, but not by pontomedullary transection, suggesting the mediation via the brain stem. It is suggested that gastric relaxations and contractions induced by acupuncture are mediated via the somato-sympathetic and somato-parasympathetic neural pathway, respectively. We will study whether acupuncture to the hind limb stimulates c-Fos expression at the dorsal motor nucleus of vagi (DMV), neural activity of vagal efferent and ACh release from the gastric wall. Acupuncture of the lower extremity has been used to treat the patients with anorexia and postoperative ileus in China. Our preliminary study demonstrated that acupuncture to the hind limb potentiates gastric contractions and accelerates solid gastric emptying in conscious rats. It has been demonstrated that gastric emptying is delayed in diabetic rats and that the origin of the delayed gastric emptying was implied to be because of impaired vagal tone. We will study whether acupuncture improves impaired gastric emptying in diabetic rats. Although the mechanism of postoperative ileus still remains unclear, the possibility of reduced vagal tone and increased sympathetic tone has been suggested. We will study whether acupuncture shortens the period of postoperative ileus in rats. This study would provide beneficial information for patients with gastroparesis and postoperative ileus.