Effects of various amino acids on gastric lesions induced by acetylsalicylic acid (ASA) and gastric secretion in pylorus-ligated rats

The simultaneous oral administration of various amino acids such as L-lysine, L-arginine, L-histidine, L-serine and others at 750, 250 or 83.3 mg/kg in pylorus-ligated rats produced a marked prevention of the gastric mucosal damages caused by oral acetylsalicylic acid (ASA) at 100 mg/kg. In regard with L-lysine and L-arginine, it was assumed that these amino acids might inhibit the ASA-induced gastric lesions through neutralization of acid because of the high alkalinity of these amino acids. In addition, the lesser effect of the hydrochoride salts of these amino acids as compared with the free form on ASA-induced gastric lesions was observed. The other effective amino acids markedly prevented the back diffusion of acid in response to ASA, suggesting as one of the possible mechanisms of lesion formation. However, L-cysteine, which exerted insignificant effect on ASA-induced gastric lesions, also prevented the back diffusion of acid even though the Na+ concentration had not returned to the control level.

Effects of acetylsalicylic acid (ASA), ASA plus L-glutamine and L-glutamine on healing of chronic gastric ulcer in the rat

A chronic gastric ulcer model was produced in rats by the subserosal injection of 20% acetic acid solution (0.015 ml) in order to examine whether (1) acetylsalicylic acid (ASA) irritates the chronic gastric ulcer in active or healed or diminished stage, (2) L-glutamine, given together with ASA, inhibits the adverse effect of ASA. Oral ASA 200 mg/kg/day, given in two divided doses for 10 consecutive days, apparently delayed the healing of the gastric ulcer and irritated the healed ulcer to reulcerate. L-Glutamine, 1,500 mg/kg/day, which was given together with ASA in two divided doses, markedly protected the gastric ulcer both in active and healed stages from the deleterious activity of ASA.

Effects of L-glutamine on various gastric lesions in rats and guinea pigs

Effects of L-glutamine on gastric lesion models in rats and guinea pigs were studied. Shay ulceration in rats was not inhibited by oral L-glutamine. Although stress-induced gastric lesions in intact rats were not inhibited by L-glutamine, a strong antagonism of gastric lesions was induced in pylorus-ligated rats under the same stress by the amino acid. Histamine-induced gastric lesions in intact rats and guinea pigs were also markedly inhibited by L-glutamine. L-Glutamine inhibited the gastric lesions in rats induced by compound 48/80 but not significantly. Reserpine- or serotonin-induced gastric lesions in rats were not affected by L-glutamine. The mechanism of L-glutamine protection was discussed.

Effects of L-glutamine on acetylsalicylic acid-induced gastric lesions in normal and cirrhotic rats

Cirrhosis of the liver in rats was induced by the administration of carbon tetrachloride (0.1 ml/100 g of body weight, s.c.) biweekly for 13 weeks. In the pylorus ligation preparation, acetylsalicylic acid (ASA) 100 mg/kg p.o. induced much more serious gastric damage in CC14-induced cirrhotic rats as compared with rats with a normal liver. L-glutamine 750 mg/kg p.o. prevented the ASA-induced gastric lesions in both normal and cirrhotic rats, even though the degree of the inhibition was weaker in cirrhotic rats. Gastric analysis indicated that L-glutamine 750 mg/kg p.o. markedly inhibited the gastric ionic changes (acid back diffusion) in response to ASA in both cirrhotic and normal rats.

Inhibitory effect of L-glutamine on gastric irritation and back diffusion of gastric acid in response to aspirin in the rat

L-Glutamine given orally at 750 mg/kg significantly reduced the formation of gastric mucosal lesions induced by aspirin at 100 mg/kg at 1, 3, and 7 hours in pylorus-ligated rats. L-Glutamine markedly inhibited the loss of H+ and a corresponding increment of Na+ through the aspirin-damaged mucosal barrier, which suggests inhibition of acid back diffusion as the mechanism of action. In vagotomized rats, the diffusion of H+ from the instilled acid solution into the gastric mucosa and outflux of Na+ from the mucosa into the lumen was so strong that aspirin could not show any acceleration of a back diffusion of H+ in contrast to the aspirin-free group. However, L-Glutamine given with or without aspirin inhibited the group. However, L-Glutamine given with or without aspirin inhibited the back diffusion of H+ instilled into the vagotomized rat stomach.

Influence of the proximal small intestine on the gastric hypersecretion in pylorus-ligated rats

The mechanism of the gastric secretory inhibition caused by the simultaneous ligation of the upper and lower duodenum or the jejunum in pylorus-ligated rats was studied. The data obtained from the experiments on surgical manipulation of the small intestine indicated that the absorption of certain substances appeared to be important in maintaining gastric secretion of pylorus-ligated rats. The participation of biliary secretion was negligible, while the ligation procedure per se, which results in the accumulation of duodenal contents, might be partly involved in the mechanism of acid secretion. Pharmacological techniques suggested that the inhibition appeared to be independent of cholinergic nervous reflex and hormonal influence, which is assumed to be released by intestinal acidification.

Influence of L-glutamine on aspirin-induced gastric lesions and absorptions as well as antipyretic, analgesic and anti-inflammatory effects of aspirin in rats and mice

L-glutamine markedly suppressed the development of the gastric lesions induced by aspirin in pylorus-ligated rats. In non-ligated normal rats, aspirin was absorbed rapidly after administration and was maintained in the blood in high salicylate concentration thereafter. When aspirin was administered in combination with L-glutamine, the absorption of aspirin was at nearly the same level as when aspirin had been given alone. In pylorus-ligated rats, administration of aspirin was followed by slow increment in blood salicylate concentration. Blood salicylate level in these rats was higher when aspirin was administered in combination with L-glutamine than when it had been given alone. Combined administration of aspirin and L-glutamine produced little influence on the antipyretic, analgesic and anti-inflammatory effects of aspirin in non-ligated normal rats.

Inhibitory effect of L-glutamine on the aspirin-induced gastric lesions in the rat

The effects of an amino acid, L-glutamine, on aspirin-induced gastric lesions and gastric secretion were studied in either intact or pylorus-ligated rats. L-Glutamine had a pronounced inhibitory effect on gastric lesions induced by aspirin administered by oral, intraperitoneal, or intraduodenal routes to intact or pylorus-ligated rats. By the oral route the inhibition was dose-related. However, L-glutamine given either intraduodenally or intraperitoneally did not show any appreciable effects on gastric lesions induced by orally administered aspirin in pylorus-ligated rats. One mechanism of L-glutamine protection was inhibition of a back diffusion of gastric acid caused by aspirin and this was demonstrated in pylorus-ligated rats. The reduction in H+ and increase in Na+ concentrations in the lumen caused by aspirin was returned to normal by increasing doses of L-glutamine. In addition, L-glutamine was considered to inhibit the back diffusion of acid caused by pylorus ligation per se, because the amino-acid produced an increment of H+ and reduction of Na+ and K+ in comparison with the control group. The role of pepsin on L-glutamine protection was negligible.