Immunohistochemical and Morphologic Basis for Glutamate Signaling in the Rat Stomach

Iijima, Junko; Horie, Sawa; Hasegawa, Rumi; Yasui, Hiroaki; Takami, Shigeru

doi:10.1248/bpb.31.1838

Cited by 9 publications

(7 citation statements)

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“…In addition, 5-HT 3 -and nitric oxide synthase-expressing cells, which are involved in glutamate signaling, have also been found in an immunohistochemical study in the rat stomach (11). In the present study, we found that intrapouch administration of MSG stimulated upper gut motility in Pavlov pouch dogs but did not stimulate it in the vagally innervated antral pouch.…”

Section: Discussionsupporting

confidence: 69%

“…It has been reported that the candidates for umami receptor are T1R1/T1R3, mGluR1, and mGluR4 (5,19,25,32). Interestingly, several recent reports have shown that these receptors are also expressed in the upper gastrointestinal mucosa of humans, rats, and mice (1,3,11,26).Physiological studies have reported that intragastric administration of MSG increases the firing rate of afferent fibers in the gastric branch of the rat vagus nerve (34). Furthermore, intragastric administration of MSG has induced activation in forebrain regions via the vagus nerves (33).…”

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confidence: 99%

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

Toyomasu

Mochiki

Yanai

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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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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Section: Discussionsupporting

confidence: 69%

mentioning

confidence: 99%

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

Toyomasu

Mochiki

Yanai

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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“…In contrast, hepatic afferents respond to all amino acids delivered into the portal vein (32). Luminal Glu activates the vagal afferents in the gastric submucosa through the paracrine cascade, led by nitric oxide and followed by serotonin (5-HT), which in turn interacts with 5-HT3 receptors on afferent fibers (2,33).…”

Section: Dietary Glutamate and Digestive Functionsmentioning

confidence: 99%

Dietary monosodium glutamate enhances gastric secretion

et al. 2009

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Dietary L-glutamate (Glu), an amino acid abundant in many foodstuffs in a free form, is able to modulate physiological functions in the stomach, including secretion and motility. Recently, specific receptors for Glu were identified in the apical membrane of chief cells in the lower region of fundic glands and in the somatostatin-secreting D-cell fraction of the gastric mucosa. This Glu-sensing system in the stomach is linked to activation of the vagal afferents. Among 20 kinds of amino acid, luminal Glu alone activated the vagal afferents in the stomach through a paracrine cascade led by nitric oxide and followed by serotonin (5-HT). In dogs with Pavlov pouches, found that supplementation of an amino acid-rich diet lacking Glu with monosodium Glu (MSG) enhanced the secretion of acid, pepsinogen, and fluid. However, MSG did not affect these secretions induced by a carbohydrate-rich diet and it had no effect on basal secretion when MSG was applied alone without the diet. Enhancement of gastric secretion by MSG was abolished by blockage of the gastric afferents using intra-gastric applied lidocaine. This effect of MSG was due in part to stimulation of 5-HT(3) receptors in the gastric mucosa.

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“…MSG is known to bind to receptors on taste cells in the oral cavity and also in the upper gastrointestinal mucosa [3,4]. It elicits a palatable taste, improves appetite, and stimulates secretions from the gastrointestinal exocrine systems [5] as well as the release of insulin [6].…”

Section: Introductionmentioning

confidence: 99%

Histological and immunohistochemical study of the effect of monosodium l-glutamate on the jejunal mucosa of adult albino rat and the possible role of propolis

Mousa

2013

The Egyptian Journal of Histology

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Monosodium l-glutamate (MSG) is used as a flavor-enhancing agent in many kinds of food products. It has been considered to induce a variety of side effects. Propolis is a bee product that has a broad spectrum of biological activities including antioxidative, antimicrobial, and anti-inflammatory effects. Aim of the workThis work aimed to study the effect of MSG on the jejunal mucosa of adult albino rat and to evaluate the possible role of propolis as a protective agent. Materials and methodsAdult male albino rats (n=40) were randomly divided into four equal groups: control group, propolis-treated group (100 mg/kg body weight), MSG-treated group (15 mg/kg body weight), and a group treated with both propolis and MSG. The animals were treated orally once daily for 6 weeks. Specimens from the jejunum were processed for light and electron microscopy. Immunohistochemical study was carried out to detect the inducible isoform of nitric oxide synthase in the epithelial cells covering the villi and lining the crypts. The results were analyzed statistically. ResultsSpecimens from MSG-treated animals showed distortion and focal loss of the villi, disorganization and shedding of the enterocytes, cytoplasmic vacuolation, and nuclear irregularity. The lamina propria showed congested dilated blood capillaries and infiltration with inflammatory cells. Ultrastructurally, focal loss of microvilli, widening of the intercellular spaces, and swollen mitochondria with disrupted cristae were observed in some enterocytes. Immunohistochemical study showed a highly significant increase in the immunoreaction in the cytoplasm of epithelial cells. In contrast, minimal changes were observed in rats treated concomitantly with both propolis and MSG, with a nonsignificant increase in the immunoreaction. Conclusion MSG induced structural changes in rat jejunal mucosa that could be ameliorated by concomitant treatment with propolis. Keywords:inducible isoform of nitric oxide synthase, jejunum, monosodium l-glutamate, propolis Egypt J Histol 36:725-734

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Immunohistochemical and Morphologic Basis for Glutamate Signaling in the Rat Stomach

Cited by 9 publications

References 10 publications

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

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

Dietary monosodium glutamate enhances gastric secretion

Histological and immunohistochemical study of the effect of monosodium l-glutamate on the jejunal mucosa of adult albino rat and the possible role of propolis

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