Dietary fish oil increases fat absorption and fecal bile acid content without altering bile acid synthesis in 20-d-old weanling rats following massive ileocecal resection

Abstract

Introduction: Dietary fish oil (FO) was reported to lower fecal fat excretion in a weanling rat model of short bowel syndrome (SBS) after ileocecal resection (ICR), and to induce changes in secretion and synthesis of bile acid (BA) in adults. We hypothesized that dietary FO, as compared with corn oil (CO), increases intestinal fat absorption in weanling SBS rats in part due to increased hepatic BA synthesis and luminal BA concentrations.

Methods: After undergoing ICR, 20-d-old rats were fed ad lib for 7 d with a CO or FO diet containing 5% sucrose polybehenate (SPB), a marker for dietary fat absorption. Fecal fatty acid, fecal and intestine luminal BA, liver mRNA expressions of cholesterol 7α-hydroxylase (Cyp7α1) and sterol-12α-hydroxylase (Cyp8β1), and serum 7α-hydroxy-4-cholesten-3-1 (7αC4) levels were determined.

Results: As compared with CO-ICR rats, FO-ICR rats had higher intestinal absorption of total fat and most individual fatty acids. Although the BA content per gram of dry stool was increased in FO-ICR rats, there were no differences between groups for the BA content in remnant jejunum, liver mRNA expression of BA biosynthetic enzymes, Cyp7α1 and Cyp8β1, or serum 7αC4, a marker for BA synthesis.

Conclusion: Dietary FO increases dietary fat absorption without increasing hepatic BA synthesis in weanling SBS rats.

Figures

Figure 1

Daily body weight. surgery was performed at 20 d of age. The daily postoperative body weight is expressed as % of preoperative weight (dotted line at 100%). Open circles: corn oil-ileocecal resection group (n = 7); filled circles: fish oil-ileocecal resection group (n = 7) rats.

Figure 2

Intestinal absorption of total dietary fat and FBA content in 20-d-old ileocecal resection (ICR) rats fed with a corn oil (CO) or fish oil (FO) diet containing 5% sucrose polybehenate. (a) Total fat absorption (%) is displayed for each pair of rats (without SD) and as the two groups (with SD). ICR rats in the CO (n = 7, white bars) and FO groups (n = 7, gray bars) were matched by body weight and length of the respected small bowel. *P < 0.05, CO-ICR vs. FO-ICR rats. (b) FBA contents are displayed for each pair of rats (without SD) and as the two groups (with SD). ICR rats in the CO (n = 7, white bars) and FO groups (n = 7, gray bars) were matched by body weight and length of respected small bowel. *P < 0.05, CO-ICR vs. FO-ICR rats. (c) FBA content was positively correlated with total fat absorption in CO-ICR (n = 7, open circles) and FO-ICR (n = 7, filled circles) rats (r2 = 0.6926, P < 0.001). FBA, fecal bile acid.

Figure 3

Intestine luminal BA contents in segments of remnant jejunum in 20-d-old corn oil-ileocecal resection (n = 6, white column) and fish oil– ileocecal resection (n = 6, gray column) rats. I, II, III, and IV on the x axis: the four quartiles of remnant jejunum from proximal to distal. BA, bile acid.