THE EFFECT OF HEPARIN ON TRINITROBENZENE SULFONIC ACID-INDUCED COLITIS IN THE RAT

Background: Reduced blood coagulability seems to protect against infla mmatory bowel disease; pilot studies using heparin in patients with in flammatory bowel disease have reported positive results, Aim: To evalu ate the effects of heparin treatment on microangiographic and on infla mmatory parameters in experimental colitis, induced by trinitrobenzene sulphonic acid (TNBS)-ethanol, Methods: Four groups of rats: (i) cont rols (saline enema), TNBS-induced colitis with (ii) sham treatment (sa line, s.c.), (iii) dexamethasone (0.25 mg/kg/day s.c.) and (iv) hepari n (500 U/kg t.d.s., s.c.), Microangiography was performed 2 and 4 days after colitis induction, Partial thromboplastin time. colonic wet wei ght, macroscopic damage score and mucosal myeloperoxidase (MPO) activi ty were determined at day 4. Results: TNBS-induced colitis caused a re duction in visible bowel wall vessels, which was prevented by heparin (P < 0.05) but not by steroids. The macroscopic damage scores and colo n wet weights were similar in all colitis groups, Compared to untreate d colitis the MPO activity in heparin-treated animals was of borderlin e significance. Conclusions: Heparin treatment improved microangiograp hic features and reduced inflammation to a certain degree. Steroids de layed development of colon hypoperfusion, but were ineffective on MPO activity, It remains to be determined if the observed effects are due to the antithrombotic activity of heparin or to an antiinflammatory ac tion.