These results confirmed the importance of enterobacteria and iNOS/NO in the pathogenesis of indomethacin-induced small intestinal lesions, and suggested that rebamipide prevents the development of these lesions, probably by its radical scavenging action.
Both alendronate and risedronate have mucosal irritative and healing impairing effects in the stomach, yet the effect of risedronate was much less pronounced compared to alendronate. It is assumed that risedronate is safer than alendronate as the antiresorptive agent in patients with diseases related to bone remodeling.
Cyclooxygenase (COX)-2 inhibitors have been developed as new gastric sparing anti-inflammatory drugs. We previously reported that the ulcerogenic response to conventional nonselective COX inhibitors, such as indomethacin and aspirin, was markedly increased in arthritic rats. The ulcerogenic effect of selective COX-2 inhibitors in arthritic animals, however, remains unknown. The present study was designed to examine the influence of selective COX-2 inhibitors, such as rofecoxib and celecoxib, on gastric mucosal integrity in rats with adjuvant-induced arthritis. Arthritis was induced in male dark Agouti rats by injection of Freund's complete adjuvant into the right hind paw. Two weeks after the injection, the animals were fasted for 18 h, various COX inhibitors were administered orally, and the mucosa was examined for lesions 4 h later. Oral administration of indomethacin caused hemorrhagic gastric lesions in both normal and arthritic rats, although the severity of lesions was significantly greater in the latter group. In contrast, neither rofecoxib nor celecoxib caused any gastric damage in normal rats, but both drugs provoked hemorrhagic gastric lesions in arthritic rats. The expression of COX-2 mRNA and immuno-positive cells was observed in the gastric mucosa of arthritic but not normal rats. The gastric mucosal prostaglandin (PG) E 2 content was significantly elevated in arthritic rats in a rofecoxib-sensitive manner. In conclusion, COX-2 inhibitors produce gastric lesions in arthritic rats, similar to the nonselective COX-inhibitors. COX-2 is up-regulated in the stomach of arthritic rats, and PGs produced by COX-2 play a role in maintaining the integrity of the gastric mucosa.
ABSTRACT-The effect of thiaton [3-(di-2-thienylmethylene)-5-methyl-trans-quinolizidinium bromide], an antispasmodic drug, on indomethacin-induced intestinal damage was examined in rats. The animals were given indomethacin, s.c., and the intestinal mucosa was examined 24 h later. Thiaton or atropine was given s.c. twice, 30 min before and 8 h following indomethacin. Indomethacin caused intestinal damage, accompanied with increase in enterobacterial translocation as well as inducible nitric oxide synthase (iNOS) and myeloperoxidase (MPO) activities, and these changes were significantly prevented by supplementation with 16,16-dimethyl prostaglandin E 2 (dmPGE2). Treatment of the animals with thiaton dose-dependently prevented the intestinal damage, together with the suppression of MPO and iNOS activities, and these effects were similarly observed by atropine. The increase of bacterial translocation was also significantly prevented by both thiaton and atropine, similar to dmPGE2. Indomethacin enhanced intestinal motility, and this effect was inhibited by either thiaton, atropine or dmPGE2. The intestinal mucus and fluid secretions were decreased by indomethacin but enhanced by dmPGE2. Both thiaton and atropine slightly decreased these secretions under basal conditions but significantly reversed the decrease in the secretions caused by indomethacin. These results suggest that thiaton protects the small intestine against indomethacin-induced damage and inflammatory changes, and this effect is related with prevention of enterobacterial translocation, the process being associated with inhibition of intestinal hypermotility caused by indomethacin, probably due to anti-muscarinic action.
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