Alterations in the gastro-intestinal functions during the development of adjuvant disease in rats.

Gastric biliary and pancreatic secretions were examined in Lewis rats with adjuvant-induced polyarthritis. By application of the pylorus-ligation technique according to Shay for 4 h, a marked increase in gastric secretion was detected from day 11 to day 54 after adjuvant injection. The changes were manifest by a decrease of pH and an increase of secretory volume as well as total acid output. Maximum values were reached at the 23rd day with an acid secretion 4 times higher than in healthy animals. The enhanced hydrochloric acid secretion in adjuvant arthritic rats was confirmed with the aid of the gastric perfusion technique according to Ghosh and Schild and by the finding that the gastric contents of conscious arthritic rats under standard feeding conditions showed a statistically significant higher acidity (pH 2.5) than normal rats (pH 4.0). Adjuvant arthritic rats with acute bile fistulas exhibited a basal and stimulated bile and pancreatic secretion like normal rats. The gastric mucosa of rats with adjuvant disease is highly sensitive to the irritant effect of gastric hypersecretion in the pylorus-ligation technique. The ulcer rate increases during the progress of the disease with a maximum of 70% at the 37th day. Normal rats with 4 h-pylorus ligation showed no macroscopically visible lesions. Increased sensitivity of the gastric mucosa against the ulcerogenic activity of non-steroidal anti-rheumatic drugs was demonstrated for aspirin and indomethacin. The etiological role of disease stress for the high susceptibility of the arthritic rat to gastric ulceration is discussed.