Mechanism of acupuncture-induced gastric motility / 全日本鍼灸学会雑誌

ABSTRACT

Effects of acupuncture on gastric motility in anesthetized rats<BR>Acupuncture has been used to treat gastrointestinal symptoms in. China for more than 3, 000 years. However, the mechanism of the beneficial effects of acupuncture remains mysterious. Strain gage transducers were implanted on the serosal surface of the stomach to record circular muscle contractions in thiobutabarbialanesthetized rats. Acupuncture on the right lower abdomen caused a transient relaxation of the stomach. Acupuncture-induced gastric relaxations were abolished by guanethidine, propranolol, splanchnic ganglionectomy, spinal cord transection, and spino-medullary transection. In contrast, NG-nitro-L-arginine, phentolamine, truncal vagotomy and ponto-medullary transection had no effect. Acupuncture increased the number of c-Fos immunopositive cells at the rostral ventrolateral medulla (RVLM). It is concluded that acupuncture-induced gastric relaxations are mediated via somato-sympathetic reflex. Its afferent limb is composed of abdominal cutaneous and muscle afferent nerves. Its efferent limb is the gastric sympathetic nerve and the reflex center is within the medulla. RVLM neurons may play an important role in mediating this reflex.<BR>Effects of acupuncture on gastric motility in conscious rats<BR>Of 35 rats studied, 60% showed no cyclic groupings of strong contractions (type A) and 10 rats (40%) showed the cyclic phase III-like contractions (type B) in conscious rats. In 73 % of type A rats, acupuncture on the hind limb (ST36), but not on the back, produced strong cyclic contractions lasting for more than 3 hrs. Acupuncture failed to produce phase III-like contractions in type A rats treated with atropine, hexamethonium and vagotomy. Pretreatment with naloxone significantly shortened the duration of enhanced phase III-like contractions. In 60 % of type B rats, acupuncture suppressed phase III-like contractions. These results suggest that the acupuncture on the ST36 induces dual effects, either stimulatory or inhibitory effects, on gastric motility. The stimulatory effects of acupuncture on the hind limb are mediated via wagal efferent pathway and opioid pathway.<BR>Effects of acupuncture on vasopressin-induced emesis in conscious dogs<BR>Arginine vasopressin (AVP) is a posterior pituitary hormone and recent evidence implies an involvement of AVP in vomiting and nausea of humans and animals. Vasopressin was intravenously infused at a dose of 0.1U/kg/min. Number of retching and vomiting were visually counted during the experiment. Intravenous administration of vasopressin induced retching and vomiting in all dogs tested. Retrograde peristaltic contractions (RPCs) occurred before the retching and vomiting.<BR>Electro-acupuncture (EA) of 10 HZ at PC6 decreased the number of retching and vomiting induced by vasopressin. EA also suppressed the RPCs. EA at the PC6 significantly reduced the number of episodes of retching and vomiting to 20-30 % compared to that without EA, while EA at BL21 had no significant effects on the number of episodes of retching and vomiting induced by vasopressin.<BR>To investigate whether opioid pathway is involved in EA-induced anti-nociceptive effects, naloxone was administered before EA and vasopressin infusion. EA at PC6 had no more inhibitory effects on vasopressininduced nausea and vomiting when naloxone was given. This suggests that anti-emetic effects of acupuncture is mediated via (central) opioid pathway.<BR>Effects of acupuncture on EGG in healthy volunteers<BR>The point of PC6 and ST36 are the common points for the treatment of gastric symptoms. We compared the effect of EA between PC6 and ST36 on gastric myoelectrical activity using surface electrogastrography (EGG). Eight healthy volunteers were fasted for 12 hours. On the separate days, four sessions of EA (1 Hz, 30 min) were randomly performed to each subject. The percentage of normal slow waves and tachygastria, peak dominant frequency (PDF) and peak dominant power