Effect of bowel resection and high-fat diet on heart CD36/fatty-acid translocase expression in a rat model of short-bowel syndrome.

Abstract

Long-chain fatty acids (LCFA) are the major energy substrates for the heart. In short-bowel syndrome (SBS), LCFA delivery to the myocardium decreases due to fat malabsorption. Fatty-acid translocase (FAT)/CD36 has recently been identified as a LCFA-binding protein in heart tissue. To determine the effects of bowel resection and a high-fat diet (HFD) on myocardial CD36 expression, male Sprague-Dawley rats were randomly assigned to one of three groups: sham rats fed normal chow (Sham-NC); SBS rats fed NC (SBS-NC), and SBS rats fed a HFD (SBS-HFD). Control rats underwent transection and anastomosis; SBS animals underwent 75% small-bowel resection. Rats were killed at 3 or 14 days. Total body weight, heart weight, heart-tissue total lipid, serum cholesterol, and triglycerides were determined at death. Total RNA from the myocardium was extracted using TRIZOL reagent. Northern-blot analysis was used to determine FAT/CD36 mRNA. Statistical significance was determined by Student's t-test with P values below 0.05 considered significant. SBS-NC and SBS-HFD rats had significantly lower body weights compared with Sham-NC animals. The heart weights and myocardial total lipid did not vary among experimental groups. Decreases in plasma triglycerides (38.2 +/- 3.8 vs 58.8 +/- 5.5 mg/dl, P < 0.05) and cholesterol (38.2 +/- 6.9 vs 55.3 +/- 8.2 mg/dl, P < 0.05) in SBS-NC compared to Sham-NC rats on day 3 was accompanied by a twofold increase ( P < 0.05) in myocardial CD36/FAT mRNA levels. Early exposure to HFD led to increased (vs SBS-NC) plasma cholesterol (82.9 +/- 5.7 vs 38.2 +/- 6.9 mg/dl, P < 0.05) and triglycerides (62.5 +/- 15.6 vs 38.2 +/- 3.8 mg/dl, P < 0.05), and a concomitant decrease in CD36/FAT mRNA levels (45.1 +/- 17.8 vs 86.6 +/- 15%, respectively, P < 0.05). Plasma lipid concentration and myocardial CD36/FAT mRNA levels on day 14 were not significantly different among the experimental groups. In this rat model of SBS, the heart thus reacts to decreased LCFA delivery by increased tissue CD36/FAT mRNA levels and, consequently, active LCFA uptake. A HFD increased plasma lipid concentrations and decreased CD36/FAT levels.