Ischemic preconditioning reduces intestinal epithelial apoptosis in rats

Recent experimental studies have described protective effect of ischemic preconditioning (IPC) on ischemia-reperfusion (I/R) injury of the intestine. We hypothesize that to reach a new point of view on the effect of IPC in intestinal barrier function, the relationship between I/R-induced mucosal injury and apoptosis must first be clarified. The present study was undertaken to investigate the role of IPC on intestinal apoptosis and probable contributions of bcl-2 expression to this process. We also investigated the effect of intestinal IPC on ileal malondyaldihyde levels. Forty-four male Wistar rats were randomized into four groups each consisting of 11 rats: sham-operated control, I/R group (30 min of superior mesenteric artery occlusion), IPC-I/R group (10 min of temporary artery occlusion prior before an ischemic insult of 30 min), and IPC alone group (10 min of preconditioning). Twenty-four hours later, ileum samples were obtained. Ileal malondyaldihyde levels were increased in the I/R group (31.9 +/- 18.8 vs. 106.8 +/- 39.8) but not in the IPC alone and IPC-I/R groups (38.1 +/- 13.6 and 44.7 +/- 12.7; P < 0.01). The number of apoptotic cells was significantly lower in IPC-I/R group than that of I/R group, and these findings were further supported by DNA laddering and M30 findings. Diminished bcl-2 expression observed in the ileal specimens of I/R group was prevented by IPC. Our results indicate that IPC may provide a protective effect on ileal epithelium and that this effect is probably the result of a significant increase in the expression of bcl-2 after the insult. The reversal of apoptosis by IPC might help preserving the vitality of intestinal structures that have a critical function, cessation of which often leads to multiorgan dysfunction syndrome.