Dietary Glutamate Signal Evokes Gastric Juice Excretion in Dogs

Background: Dietary-free L -glutamate (Glu) in the stomach interacts with specific Glu receptors (T1R1/T1R3 and mGluR1–8) expressed on surface epithelial and gastric gland cells. Furthermore, luminal Glu activates the vagal afferents in the stomach through the paracrine cascade including nitric oxide and serotonin (5-HT). Aim: To elucidate the role of dietary Glu in neuroendocrine control of the gastrointestinal phase of gastric secretion. Methods: In Pavlov or Heidenhain gastric pouch dogs, secretion was measured in the pouch while monosodium glutamate (MSG) was intubated into the main stomach alone or in combination with liquid diets. Results: In both experimental models, supplementation of the amino acid-rich diet with MSG (100 mmol/l) enhanced secretions of acid, pepsinogen and fluid, and elevated plasma gastrin-17. However, MSG did not affect secretion stimulated by the carbohydrate-rich diet and had no effect on basal secretion when applied in aqueous solution. Effects of MSG were abolished by denervation of the stomach and proximal small intestine with intragastrically applied Published online: March 10, 2011 Vasiliy Zolotarev, PhD Laboratory of Physiology of Digestion, Pavlov Institute of Physiology Makarova nab. 6, Saint Petersburg 199034 (Russia) Tel. +7 813 707 2738, Fax +7 812 328 0501 E-Mail vasilyzolotarev @ hotmail.com © 2011 S. Karger AG, Basel 0012–2823/11/0835–0007$38.00/0 Accessible online at: www.karger.com/dig D ow nl oa de d by : 54 .7 0. 40 .1 1 10 /6 /2 01 7 5: 54 :2 1 A M