Effect of leptin on intestinal re-growth following massive small bowel resection in rat

Recent evidence suggests that the adipose tissue-derived cytokine leptin (LEP) is involved in modulation of growth and differentiation of normal small intestine. The purpose of the present study was to evaluate the effects of parenteral LEP on structural intestinal adaptation, cell proliferation and apoptosis in a rat model of short bowel syndrome (SBS). Male Sprague-Dawley rats were divided into three experimental groups: Sham rats underwent bowel transection and re-anastomosis, SBS-rats underwent a 75% small bowel resection, and SBS-LEP-rats underwent bowel resection and were treated with LEP given subcutaneously at a dose of 20 μg/kg, once daily, from day 3 through 14. Parameters of intestinal adaptation (bowel and mucosal weights, mucosal DNA and protein, villus height and crypt depth in jejunum and ileum), enterocyte proliferation and enterocyte apoptosis were determined on day 15 following operation. Ileal tissue samples were taken for detection of bax and bcl-2 gene expression using RT-PCR technique. Statistical analysis was performed using the non-parametric Kruskal–Wallis ANOVA test, with P<0.05 considered statistically significant. Treatment with subcutaneous LEP resulted in a significant increase in jejunal (17%, P<0.05) and ileal (13%, P<0.05) bowel weight, jejunal (10%, P<0.05) and ileal (25%, P<0.05) mucosal weight, jejunal (26%, P<0.05) and ileal (38%, P<0.05) mucosal DNA, ileal (25%, P<0.05) mucosal protein, jejunal (41%, P<0.05) and ileal (21%, P<0.05) villus height, jejunal (37%, P<0.05) crypt depth, and jejunal (24%, P<0.05) and ileal (21%, P<0.05) enterocyte proliferation compared to SBS-animals. Enterocyte apoptosis increased significantly after bowel resection in jejunum and ileum compared to sham animals and was accompanied by an increased bax gene expression and a decreased bcl-2 gene expression in ileal samples. SBS-LEP rats showed a trend toward a decrease in enterocyte apoptosis in ileum and a mild decrease in bax gene expression compared to SBS-untreated animals. In conclusion, in a rat model of SBS parenteral LEP stimulates structural intestinal adaptation. Increased cell proliferation and decreased cell death via apoptosis may be responsible for this increased cell mass.