Cross-talk along gastrointestinal tract during electrical stimulation: effects and mechanisms of gastric/colonic stimulation on rectal tone in dogs

Abstract

. Cross-talk along gastrointestinal tract during electrical stimulation: effects and mechanisms of gastric/colonic stimulation on rectal tone in dogs. Am J Physiol Gastrointest Liver Physiol 288: G1195-G1198, 2005. First published February 3, 2005 doi:10.1152/ajpgi.00554.2004.-Gastric electrical stimulation (GES) has been shown to alter motor and sensory functions of the stomach. However, its effects on other organs of the gut have rarely been investigated. The study was performed in 12 dogs implanted with two pairs of electrodes, one on the serosa of the stomach and the other on the colon. The study was composed of two experiments. Experiment 1 was designed to study the effects of GES on rectal tone and compliance in nine dogs compared with colonic electrical stimulation (CES). Rectal tone and compliance were assessed before and after GES or CES. Experiment 2 was performed to study the involvement of sympathetic pathway in 8 of the 12 dogs. The rectal tone was recorded for 30 -40 min at baseline and 20 min after intravenous guanethidine. GES or CES was given for 20 min 20 min after the initiation of the infusion. It was found that both GES and CES reduced rectal tone with comparable potency. Rectal compliance was altered neither with GES, nor with CES. The inhibitory effect of GES but not CES on rectal tone was abolished by an adrenergic blockade, guanethidine. GES inhibited rectal tone with a comparable potency with CES but did not alter rectal compliance. The inhibitory effect of GES on rectal tone is mediated by the sympathetic pathway. It should be noted that electrical stimulation of one organ of the gut may have a beneficial or adverse effect on another organ of the gut. gastric electrical stimulation; colonic electrical stimulation; rectal motility; sympathetic nerve THE EFFECTS OF GASTRIC ELECTRICAL stimulation (GES) on symptoms and gastric functions have received increasing scrutiny. A number of studies has been performed to investigate the effects of GES on gastric motility, gastric emptying, and gastrointestinal symptoms in both dogs and humans (1, 3, 5, 9 -12, 15, 16, 18, 20 -22). On the basis of stimulation pulse width, GES can be classified into three categories: long pulses (on the order of milliseconds), short pulses (in the order of microseconds), and pulse trains. Although some of the results are still controversial, the majority of these studies seems to indicate that GES with long pulses at a low frequency (close to or slightly higher than intrinsic gastric slow-wave frequency) is able to normalize gastric dysrhythmias, entrain gastric slow waves, and accelerate gastric emptying (3,10,16,18,20,22). GES with short pulses at a high frequency (4 times or much higher than intrinsic gastric slow waves) is able to significantly reduce symptoms of nausea and vomiting but is minimally effective on gastric motility (1,5,9,11,12). GES with pulse trains was noted to accelerate the movement of gastric solid contents in anesthetized dogs (21) and have a therapeutic role for the treatment of obesity (6 ...

Systematic review: applications and future of gastric electrical stimulation

“…Rectal tone was reduced with GES of long pulses and the inhibitory effect was found to be mediated via the sympathetic pathway. 57 …”

Inhibitory Effects of Gastrointestinal Electrical Stimulation on Rectal Tone are both Organ-Specific and Distance-Related in Dogs

“…29 Long-pulse GES with the parameters used in this study was previously reported to induce gastric and rectal relaxation. 16,19,23 The current study was designed to systematically investigate the effects of electrical stimulation of various parts of the gut on rectal tone and to answer the following questions: 1) is the effect of electrical stimulation on rectal tone organ-specific? ; 2) is the effect of electrical stimulation associated with the distance between the stimulation organ and the rectum?…”

“…Previous studies in our laboratory have shown that both GES and CES inhibits rectal tone and CES significantly inhibits gastric tone. 16,19 It also is reported that DES has inhibitory effects on gastric emptying in healthy humans, and pyloric electrical stimulation significantly inhibits gastric myoelectrical activity, antral contractions, and gastric emptying. 11,18 However, it is still not clear whether the effect of electrical stimulation of one part of the gut on another part of the gut is related to the two involved organs or the distance between the stimulation site and the affected organ.…”

“…[13][14][15] A number of studies also have investigated the effects of GES, intestinal electrical stimulation, pyloric electrical stimulation, or CES on motility of the organ where the stimulation is initiated or some other organs along the GI tract. [11][12][13][14][15][16][17][18][19] Based on the pulse width of stimulation, electrical stimulation could be divided into three categories: long pulse (in the order of ms), short pulses (in the order of μs), and pulse trains. Available data from clinic and animal studies have shown that GES with short pulses is capable of improving symptoms of nausea and vomiting in patients with gastroparesis and in dogs.…”

“…1,5,7 Long-pulse GES is able to normalize gastric dysrhythmias, entrain gastric slow waves, accelerate gastric emptying, induce gastric relaxation, and inhibit rectal tone. 2,[6][7][8][9]16,[20][21][22][23] Long-pulse jejunal electrical stimulation is capable of accelerating intestinal transit in dogs and duodenum electrical stimulation is able to delay gastric emptying and reduce water intake in healthy humans. 11,17 CES with long pulses can significantly inhibit gastric tone and rectal tone.…”