Increases in gastric acidity in response to electroacupuncture stimulation of the hindlimb of anesthetized rats

Acupuncture treatment has been used as physiotherapy to treat gastrointestinal disorders in traditional Oriental medicine. In the present study, we selected anesthetized animals as the subjects of this experiment in order to eliminate emotional factors, and investigated the responses to acupuncture stimulation at only a single point by changing animal conditions. 1) There was marked enhancement of gastric acid secretion by electroacupuncture stimulation of the hindlimb based on pH values of the perfusate. However, the enduring response after the momentary initial decrease suggested the existence of humoral factors. 2) The electroacupuncture-specific response was not observed in rats after sciatic nerve denervation. However, the pH values of the perfusate decreased in response to electroacupuncture stimulation of the hindlimb on the sciatic nerve intact side of the same rat. This suggests that the input pathway of acupuncture stimulation was a somatic nerve efferent pathway from the hindlimb. 3) No response to electroacupuncture stimulation was observed in the rats after vagotomy, but a clear enhancement response was seen after sympathectomy, These findings show that the major efferent path of the responses to acupuncture stimulation is the vagus nerve. The results of this experiment suggest that electroacupuncture stimulation of the hindlimb of anesthetized rats increases gastric acid secretion with somatic nerves as the afferent pathway and branches of the vagus nerve to the stomach as the efferent pathway.