Electroacupuncture improves impaired gastric motility and slow waves induced by rectal distension in dogs

Abstract

puncture improves impaired gastric motility and slow waves induced by rectal distension in dogs. Am J Physiol Gastrointest Liver Physiol 295: G614 -G620, 2008. First published July 24, 2008 doi:10.1152/ajpgi.90322.2008 is known to induce upper gastrointestinal (GI) symptoms. The aim of this study was to investigate the effects and underlying mechanisms of RD on gastric slow waves (GSW) and motor activity and furthermore to investigate the effects and mechanisms of electroacupuncture (EA) on GSW and motor activity. Eight female hound dogs chronically implanted with gastric serosal electrodes and a gastric fistula were studied in six separate sessions. Antral motility, GSW, heart rate variability, and rectal pressure were evaluated for the above purposes. 1) RD at a volume of 120 ml suppressed antral motility significantly. Guanethidine blocked the inhibitory effect of RD. EA at ST36 was able to restore the suppressed antral contractions induced by RD (16.6 Ϯ 1.7 vs. 8.0 Ϯ 1.4, P Ͻ 0.001). Naloxone partially blocked the effect of EA on antral contractions. 2) RD reduced the percentage of normal GSW from 98.8 Ϯ 0.8% at baseline to 76.1 Ϯ 8.6% (P Ͻ 0.05) that was increased to 91.8 Ϯ 3.0% with EA. The effects of EA on the GSW were nullified by the presence of naloxone. 3) EA did not show any significant effect on rectal pressure, suggesting that the ameliorating effects of EA on RD-induced impaired gastric motility were not due to a decrease in rectal pressure. 4) EA increased the vagal activity suppressed by RD. In conclusion, RD inhibits postprandial gastric motility and impairs GSW in dogs, and the inhibitory effects are mediated via the adrenergic pathways. EA at ST36 is able to restore the RD-induced impaired GSW and motor activities, possibly by enhancing vagal activity, and is partially mediated via the opioid pathway. EA may have therapeutic potential for functional gastrointestinal disorders. adrenergic pathway; gastric slow waves; naloxone CHRONIC, IDIOPATHIC, slow-transit constipation and constipationdominant irritable bowel syndrome (IBS) are commonly observed in clinical practice. These patients frequently complain of upper abdominal symptoms such as bloating, upper abdominal discomfort or pain, and vomiting. The symptoms overlap with lower abdominal symptoms and are resistant to dietary and pharmacological treatments because of the constipation issues; they are related to the presence of impaired gastrointestinal myoelectrical activity and reduced upper gastrointestinal motor activity (1,4,13,31,33,37). This phenomenon has led to the hypothesis that rectal distension (RD) with fecal stasis in the colorectal region directly causes reflexive inhibition of proximal gastrointestinal motility (5,7,9,22,32,50).A number of investigations have indicated that RD induces upper gastrointestinal symptoms, inhibits gastric tone and accommodation, and delays gastric emptying (3, 14, 20 -21, 24, 34 -35, 50). However, little information about the effects of RD on gastric contractions is available, although gastric co...

Electroacupuncture improves rectal distension-induced delay in solid gastric emptying in dogs

“…Fleet Lynchburg, VA, USA), a rectal catheter with a balloon attached to its tip (the caudal pole of the balloon was about 6 cm from the anal verge) was inserted into the rectum and affixed before a test meal for gastric emptying. The balloon was inflated with 120 ml of air (7,21) only during 60 -90 min after the test meal that was identical to the meal in experiment 1. In the control session, no catheter was inserted into the rectum and no RD or EA or sham-EA was performed.…”

“…Previous studies have reported that EA at ST36 accelerated gastric emptying in both dogs and humans (34,49) and restored impaired gastric accommodation in vagotomized dogs (33). A recent study reported that EA improved RD-induced impairment of antral contractions (7). Mechanistically, a number of previous studies have shown the involvement of the opioid pathway with the prokinetic effect of EA on gastrointestinal contractions (7,42).…”

“…A recent study reported that EA improved RD-induced impairment of antral contractions (7). Mechanistically, a number of previous studies have shown the involvement of the opioid pathway with the prokinetic effect of EA on gastrointestinal contractions (7,42). However, it is unknown whether EA is also able to improve or attenuate RD-induced delay in gastric emptying, a condition mimicking delayed gastric emptying attributed to colorectal stasis or gas in constipation or IBS-C. Naloxone is a -opioid receptor competitive antagonist in the central and enteric nervous systems and has been used as a blocker to investigate the possible involvement of the opioid pathway with EA (7).…”

“…Rectal (balloon) distension (RD) mimicking fecal or gas stasis in the colorectal region is one of constipation models commonly used in the study of upper gastrointestinal motor activity. A number of studies have reported that RD impairs gastric myoelectrical activities, gastric tone, and gastric accommodation; reduces antral contractions; delays gastric emptying, and inhibits small-intestine motility in dogs and humans (1,2,7,11,21,39,54).…”

Central and Peripheral Effects of Transcutaneous Acupuncture Treatment for Nausea in Patients with Diabetic Gastroparesis

“…EA at ST36 restored rectal distentioninduced impairment in gastric slow waves in dogs and increased the spikes in rabbits. [35][36][37] EA at ST36 improved the percentage of normal gastric slow waves as well as the percentage of tachygastria in healthy volunteers. 38 Liu et al 21 reported that 2-week TEA at ST36 decreased dyspepsia symptoms and elevated vagal activity in patients with functional dyspepsia.…”