Intragastric monosodium l-glutamate stimulates motility of upper gut via vagus nerve in conscious dogs

Monosodium l-glutamate (MSG) is a substance known to produce the umami taste. Recent studies indicate that MSG also stimulates a variety of activities in the gastrointestinal tract through its receptor in the gut, but no study has reported the activity in conscious large experimental animals. The aim of our study was to investigate whether direct intragastric MSG stimulates gut motility and to identify the mechanism in conscious dogs. Contractile response to intraluminal injection of MSG was studied in the fed and fasted states by means of chronically implanted force transducers. MSG (5, 15, 45, and 90 mM/kg) dissolved in water was injected into the stomach and duodenum in normal and vagotomized dogs. MSG solution was administered into the stomach before feeding, and gastric emptying was evaluated. Several inhibitors of gastrointestinal motility (atropine, hexamethonium, and granisetron) were injected intravenously before MSG administration to the stomach. The effect of MSG was investigated in Pavlov (vagally innervated corpus pouch), Heidenhain (vagally denervated corpus pouch), and antral pouch (vagally innervated) dogs. Upper gut motility was significantly increased by intragastric MSG but not significantly stimulated by intraduodenal MSG. Intragastric MSG (45 mM/kg) stimulated postprandial motility and accelerated gastric emptying. MSG-induced contractions were inhibited by truncal vagotomy, atropine, hexamethonium, and granisetron. Gut motility was increased by intrapouch injection of MSG in the Pavlov pouch, but it was not affected in the Heidenhain or antral pouch dogs. We conclude that intragastric MSG stimulates upper gut motility and accelerates gastric emptying. The sensory structure of MSG is present in the gastric corpus, and the signal is mediated by the vagus nerve.

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Role of vagus nerve in postprandial antropyloric coordination in conscious dogs

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00195.2004 ◽

2005 ◽

Vol 288 (3) ◽

pp. G487-G495 ◽

Cited By ~ 28

Author(s):

Tomio Ueno ◽

Kenichiro Uemura ◽

Mary B. Harris ◽

Theodore N. Pappas ◽

Toku Takahashi

Keyword(s):

Gastric Emptying ◽

Vagus Nerve ◽

Late Phase ◽

Motor Pattern ◽

The Body ◽

Conscious Dogs ◽

Solid Meal ◽

Liquid Meal ◽

Vagal Blockade

It is generally believed that gastric emptying of solids is regulated by a coordinated motor pattern between the antrum and pylorus. We studied the role of the vagus nerve in mediating postprandial coordination between the antrum and pylorus. Force transducers were implanted on the serosal surface of the body, antrum, pylorus, and duodenum in seven dogs. Dogs were given either a solid or a liquid meal, and gastroduodenal motility was recorded over 10 h. Gastric emptying was evaluated with radiopaque markers mixed with a solid meal. Dogs were treated with hexamethonium, NG-nitro-l-arginine methyl ester (l-NAME), or transient vagal nerve blockade by cooling. A postprandial motility pattern showed three distinct phases: early, intermediate, and late. In the late phase, profound pyloric relaxations predominantly synchronized with giant antral contractions that were defined as postprandial antropyloric coordination. A gastric emptying study revealed that the time at which gastric contents entered into the duodenum occurred concomitantly with antropyloric coordination. Treatment by vagal blockade or hexamethonium significantly reduced postprandial antral contractions and pyloric relaxations of the late phase. l-NAME changed pyloric motor patterns from relaxation dominant to contraction dominant. Solid gastric emptying was significantly attenuated by treatment with hexamethonium, l-NAME, and vagal blockade. Postprandial antropyloric coordination was not seen after feeding a liquid meal. It is concluded that postprandial antropyloric coordination plays an important role to regulate gastric emptying of a solid food. Postprandial antropyloric coordination is regulated by the vagus nerve and nitrergic neurons in conscious dogs.

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Characteristic motor activity of the gastrointestinal tract in fasted conscious dogs measured by implanted force transducers

The American Journal of Digestive Diseases ◽

10.1007/bf01072323 ◽

1978 ◽

Vol 23 (3) ◽

pp. 229-238 ◽

Cited By ~ 34

Author(s):

Zen Itoh ◽

Shinjin Takeuchi ◽

Isamu Aizawa ◽

Ryuichi Takayanagi

Keyword(s):

Gastrointestinal Tract ◽

Motor Activity ◽

Conscious Dogs ◽

Force Transducers ◽

Characteristic Motor

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An experimental study of the gastrointestinal motility in conscious dogs with strain gauge force transducers.

Japanese Journal of Smooth Muscle Research ◽

10.1540/jsmr1965.25.97 ◽

1989 ◽

Vol 25 (3) ◽

pp. 97-111

Author(s):

Kenzo KOH

Keyword(s):

Experimental Study ◽

Gastrointestinal Motility ◽

Strain Gauge ◽

Conscious Dogs ◽

Force Transducers

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▾ Cisapride – more selective than metoclopramide

Drug and Therapeutics Bulletin ◽

10.1136/dtb.28.23.89 ◽

1990 ◽

Vol 28 (23) ◽

pp. 89-90

Keyword(s):

Gastric Emptying ◽

Gastrointestinal Motility ◽

Chemical Structure ◽

Sphincter Pressure ◽

Antiemetic Effect ◽

Gut Motility ◽

Prokinetic Drugs ◽

Similar Chemical ◽

Non Ulcer Dyspepsia ◽

Product Licence

Metoclopramide (Maxolon; Primperan), has been around for over 20 years and domperidone (Motilium - Sterling Winthrop) for eight years. Both are prokinetic drugs which speed gastric emptying, increase oesophageal sphincter pressure, stimulate gut motility and in addition have a central antiemetic effect. Cisapride (Prepulsid - Janssen; Alimix - Cilag) has a similar chemical structure to metoclopramide and is intended for the reduction of oesophageal reflux and relief of symptoms caused by impaired gastrointestinal motility. The product licence has recently been extended to include treatment of non-ulcer dyspepsia.

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Inhibitory effect of ileal oleate on postprandial motility of the upper gut

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1991.261.3.g458 ◽

1991 ◽

Vol 261 (3) ◽

pp. G458-G463 ◽

Cited By ~ 2

Author(s):

Z. Dreznik ◽

D. Brocksmith ◽

T. A. Meininger ◽

N. J. Soper

Keyword(s):

Oleic Acid ◽

Gastric Emptying ◽

Gamma Camera ◽

Delayed Gastric Emptying ◽

Early Period ◽

Inhibitory Effect ◽

Myoelectric Activity ◽

Phenol Red ◽

Mixed Meal ◽

Postprandial Motility

To determine the effect of ileal oleate on postprandial gastrointestinal motility, duodenal and paired perfusion-aspiration ileal catheters and bipolar duodenal and jejunal electrodes were surgically implanted in five dogs. The ileum was perfused with either saline or an isotonic oleic acid emulsion at 2 ml/min. A 205-kcal mixed meal containing 120 ml liquid nutrient labeled with 111In-diethylenetriamine pentaacetic acid (DTPA) and solid food labeled with 99mTc was then administered orally. Gastric emptying was assessed by a gamma camera, myoelectric activity was continuously monitored, and duodenal-ileal transit of phenol red was determined over the ensuing 240 min. Ileal oleate reduced duodenal spikeburst frequency by 50% (P less than 0.05) and delayed gastric emptying of liquids and solids. Four hours after ingesting the meal, 62% of solids and 34% of liquids were retained in the stomach during oleic acid perfusion compared with 25 and 4%, respectively, when saline was perfused (P less than 0.05). Duodenal-ileal transit was markedly slowed by ileal perfusion with the oleic acid emulsion (P less than 0.001). Ileal oleate therefore exerted a profound inhibitory effect on proximal gut motility in the early period after ingestion of a mixed-nutrient meal in dogs.

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Potential of Vagus Nerve Stimulation for Treating Impaired Gastric Accommodation and Delayed Gastric Emptying: a Preliminary Rodent Study

Gastroenterology ◽

10.1016/s0016-5085(17)33190-6 ◽

2017 ◽

Vol 152 (5) ◽

pp. S936

Author(s):

Shiying Li ◽

Sujuan Zhang ◽

Jiande Chen

Keyword(s):

Gastric Emptying ◽

Vagus Nerve ◽

Nerve Stimulation ◽

Vagus Nerve Stimulation ◽

Delayed Gastric Emptying ◽

Gastric Accommodation

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Role of EDRF/NO in parasympathetic coronary vasodilation following carotid chemoreflex activation in conscious dogs

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1994.267.2.h605 ◽

1994 ◽

Vol 267 (2) ◽

pp. H605-H613 ◽

Cited By ~ 7

Author(s):

W. Shen ◽

M. Ochoa ◽

X. Xu ◽

J. Wang ◽

T. H. Hintze

Keyword(s):

Vagus Nerve ◽

Conscious Dogs ◽

Coronary Resistance ◽

Vascular Response ◽

Coronary Vasodilation ◽

Relaxing Factor ◽

Anesthetized Dogs ◽

Endothelium Derived Relaxing Factor ◽

Stimulation Of

The role of endothelium-derived relaxing factor (EDRF) in parasympathetic coronary vasodilation following carotid chemoreflex activation induced by nicotine in conscious dogs and stimulation of the vagus nerve in anesthetized dogs was studied. Injection of nicotine (11 +/- 4 micrograms) into the carotid artery increased coronary blood flow (CBF) by 126 +/- 16% from 28 +/- 3 ml/min and reduced late diastolic coronary resistance (LDCR) by 43 +/- 4% from 3.58 +/- 0.52 mmHg.ml-1.min, accompanied by a significant increase in mean arterial pressure and a decrease in heart rate (all P < 0.01). Pacing and propranolol did not change the coronary vascular response to chemoreflex activation. There were still increases in CBF by 113 +/- 17% from 29 +/- 3 ml/min and decreases in LDCR by 41 +/- 5% from 3.13 +/- 0.52 mmHg.ml-1.min (all P < 0.01). After infusion of N omega-nitro-L-arginine (L-NNA) (30 mg/kg), the increase in CBF following chemoreflex activation was only 23 +/- 3% from 37 +/- 3 ml/min, and the fall in LDCR was 19 +/- 3% from 3.09 +/- 0.51 mmHg.ml-1.min. Stimulation of the vagus nerve showed a relationship between stimulation frequency and coronary vasodilation that was significantly inhibited by L-NNA. Thus EDRF plays an important role in mediating parasympathetic coronary vasodilation during chemoreflex activation and perhaps during many reflexes that cause vagal cholinergic vasodilation in the heart.

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