Effect of cimetidine on gastric tissue mucous contents in rats subjected to stress

Morphine enhances gastric mucus synthesis in rats

The effect of morphine on gastric mucus synthesis was studied in conscious rats, using the method of staining mucus with alcian blue then destaining it with magnesium chloride. It was found that morphine significantly enhanced gastric mucus synthesis, as did fentanyl, a non-histamine-liberating opioid. The effects of the opioids on mucus synthesis were significantly attenuated by pretreatment with naloxone 8 mg/kg or cimetidine 100 mg/kg. Cimetidine itself significantly suppressed gastric mucus production in saline-treated rats. These findings suggest that the increased gastric mucus synthesis caused by morphine is due to activation of opiate receptors and not to histamine release. It appears that cimetidine may counteract rather than block the receptor effects of the opioids by a direct action on the mucus-secreting glands.

Changes in the Incorporating Activity of 35S-Sulfate into Gastric Sulfated Glycoproteins in the Rat with Erosions by Restraint and Water Immersion Stress

The synthetic activity of rat gastric sulfated glycoproteins (SGP) in vitro was investigated at various time intervals after water immersion stress using 35S-sulfate as a precursor. More than 90 percent of the total radioactivity was incorporated into mucosal SGP, and the rest was incorporated into glycosaminoglycans in the gastric muscular layer. The incorporation of 35S-sulfate into SGP increased at 2 hr and decreased at 6 hr after the onset of stress. The incorporating activity again increased markedly at 12 hr and then recovered to the normal level at 24 hr after the onset of stress. An anti-ulcer agent, N-(N-acetyl-beta-alanyl)-L-histidine aluminum complex (AAHA), significantly increased the SGP synthetic activity at 12 hr and at 24 hr after the onset of stress. It was indicated from the elution patterns on the DEAE-cellulose column that AAHA increased the amount of highly sulfated glycoproteins compared with the stress control at 12 hr after the onset of stress. The uronic acid content in the gastric muscular layer of the rat was unchanged with stress. These results in the in vitro experiment indicate that the SGP synthetic activity does not decrease with stress load, but rather increases at 2 hr and at 12 hr after the onset of stress when a sufficient amount of 35S-sulfate is supplied. Accordingly, it is suggested that SGP facilitates the restoration of the gastric mucosal damage caused by stress.