Adaptive response of apolipoprotein A-I and A-IV mRNA in residual ileum after massive small bowel resection in rats.
The response of apolipoproteins, which are synthesized mainly in the small intestine, after small bowel resection has not been documented. In this study, we investigated the effect of small bowel resection on the expression of apolipoprotein mRNA in the residual ileum in rats. Wistar rats underwent either an 85% jejunoileal resection or a sham-operation. Plasma concentrations of total and HDL-cholesterol, apolipoprotein A-I and A-IV were measured on days 0, 3, 6, 9, 12, and 16 (surgery on day 1). The abundances of apolipoprotein mRNA in the residual ileum and liver on day 16 were determined. Plasma levels of total and HDL-cholesterol and apolipoprotein A-I and A-IV in resected rats were significantly lower than in sham-operated rats on days 3 and 6. Resected rats showed a significant increase in ileal apolipoprotein A-I (1.2-fold) and A-IV (3.2-fold) mRNA compared with sham-operated animals. Hepatic apolipoprotein mRNA were the same between two groups. These data suggest that the residual ileum adapts to jejunoileal resection by selective increases in apolipoprotein A-I and A-IV expression at a pretranslational stage. The recoveries of apolipoprotein A-I and A-IV in plasma appear to depend, at least in part, on the increased expression of these apolipoproteins in the residual ileum.