LUMINAL SHORT-CHAIN FATTY-ACIDS AND POSTRESECTION INTESTINAL ADAPTATION

Background: Short-chain fatty acids (SCFAs) reportedly have a trophic effect on the small intestine. How-ever, it is unclear if this is a lo cal or primarily systemic effect. Loss of the ileocolonic junction (LC J) may result in increased SCFAs and bacteria in the small intestine f rom colonic reflux. Our aim was to evaluate the effect of bypass of th e ICJ on intestinal SCFA content and postresection adaptation. Methods : Thirty dogs were studied: transection control (TC, n = 10), distal r esection of 50% intestine (DR, n = 10), and distal resection with bypa ss of ICJ (DRBP, n = 10). Animals were killed at 4 and 12 weeks. Lumin al SCFAs and bacteria and adaptation of the small intestine were evalu ated. Results: Caloric intake was significantly less in the two resect ed groups (67 +/- 3 DR and 63 +/- 3, DRBP vs 78 +/- 5 kcal/kg/ d TC, p < .05). Body weight and albumin levels were decreased at 12 weeks but were similar between the resected groups (81% +/- 3% and 74% +/- 6% i nitial and 1.9 +/- 0.1 and 2.1 +/- 0.2 g/dL, DR and DRBP, respectively ). Steatorrhea was present for 12 weeks after resection and was greate r after DRBP (14.2% +/- 3.8% vs 8.6% +/- 1.9% at 4 weeks and 13.6% +/- 2.5% vs 6.7% +/- 0.6% at 12 weeks, P < .05). Bypassed animals had ele vated intraluminal SCFA content (3126 +/- 1004 vs 1791 +/- 538 DR and 1600 +/- 446 mu g/mL TC, p < .05) and anaerobic bacterial counts (100% vs 50% and 44%, respectively). Tissue inflammation and myeloperoxidas e activity were similar. Small intestinal length (174 +/- 10 and 180 /- 10 cm) and circumference (5.2 +/- 0.4 and 5.2 +/- 0.3 cm) increased to a similar ex-tent in both resected groups at 12 weeks. Thickness o f mucosa (1939 +/- 162 vs 1662 +/- 162 mu m) and muscle (865 +/- 45 vs 978 +/- 79 mu m) layers were similar after DR and DRBP. Conclusion: ( 1) Bypass of the ICJ after distal resection results in increased growt h of anaerobic bacteria and luminal SCFA and is associated with more m arked steatorrhea. (2) Bypass of the ICJ does not influence structural adaptation of the small intestine. (3) These findings do not support a local trophic effect for SCFA.