Beneficial effects of angiotensin converting enzyme inhibitors captopril and enalapril on experimentally induced colitis in rats

ABSTRACT

Increasing evidence supports an association between inflammation and angiotensin converting enzyme [ACE]. The aim of this study was to examin the efficacy of ACE inhibitors [ACEIs] namely, captopril and enalapril on acetic acid induced colitis in rats. Colitis was induced by intracolonic injection of 2 ml of 3% acetic acid. Eighty rats were studied in this study, divided into two main groups, group 1, 40 rats of long duration of inflammation and treatment and group II, 40 rats of short duration of inflammation and treatment. Each group was subdivided into 4 subgroups. 10 control rats, 10 rats injected intracolonic with acetic acid [acetic acid untreated rats], 10 rats injected intracolonic with acetic and plus oral administration of captopril [captopril treated rats], and 10 rats injected intracolonic with acetic acid plus oral administration of enalapril [enalapril treated rats]. Captopril and enalapril were given 2 days after induction of colitis and continued daily for 3 weeks in group I, and for 2 days before and 2 days after induction of colitis in group II. Intracolonic acetic acid injection produced a significant inflammation, assessed by the ulcer index score, the weight of the colon and the colonic tissue level of myeloperoxidase enzyme, in acetic acid untreated rats of both groups. These parameters were significantly improved by ACEIs administration. The effect of captopril in group I was more potent than enalapril, while in group II both ACEIs had the same effect. in group II captopril succeeded to inhibit the change in the weight of the colon or the tissue level of myeloperoxidase enzyme. The colonic tissue level of glutathione reductase was significantly reduced in acetic acid untreated rats of both groups. This reduction was significantly inhibited by ACEIs administration in both groups, with better results with captopril treated rats than enalapril ones in group I. Also the efficacy of captopril in group I was more significant than in group II in improving the glutathione reductase colonic tissue level. Captopril and enalapril also sigificantly improved the level of tissue lipid peroxides, which was significantly elevated in acetic acid untreated rats of both groups. However, the efficiency of captopril in reducing the lipid peroxides level was mor significant than enalapril in both groups. this study provides an evidence that the two ACEIs particularly captopril confers a good anti-inflammatory activity against colitis in rats leading to improvement of oxidative stress induced by the inflammatory insult