Novel effect of leptin on small intestine adaptation

Leptin is a 16-kDa peptide produced by adipocytes that plays an important role in the regulation of body fat and satiety. We have previously shown that leptin is a growth factor for normal rat small intestine. This study was designed to examine the effect of systemic leptin administration on small bowel absorptive function after massive small bowel resection (MSBR).

Twenty-one adult male Sprague-Dawley rats underwent an 80% small bowel resection and end-to-end jejunoileal anastomosis. Seven days following resection, all rats had placement of a jugular venous catheter connected to a subcutaneously placed osmotic minipump and were divided into three groups based on the content of each minipump: Group 1 (n = 7) 0.1% bovine serum albumin; Group 2 (n = 7) leptin 2 microg/kg/day; and Group 3 (n = 7) leptin 4 microg/kg/day. Following a 14-day infusion period, [(14)C]galactose absorption was measured using a closed-recirculation technique. Mucosal DNA content was determined for all groups using a standard DNA purification kit. Mucosal RNA was extracted and RT-PCR was performed using the following primers: sodium/glucose cotransporter (SGLT-1), fructose transporter (GLUT-5), and glyceraldehyde-3-phosphate dehydrogenase, an internal standard. PCR products were separated on a 4% agarose gel and relative band intensities were measured. Statistical analysis was performed using ANOVA and expressed as means +/- SEM.

Group 2 showed a 44% increase in galactose absorption (P < 0.01) and a 14% increase in GLUT-5 band intensity (P < 0.05), but no change in DNA content or SGLT band intensity.

This study demonstrates for the first time that leptin enhances small intestine carbohydrate absorption beyond the normal adaptive response following MSBR. Leptin may be clinically useful in patients with inadequate intestinal function.