Abstract 687 Poster Session II, Sunday, 5/2 (poster 152)

Background: Apolipoproteins (apo) B, A-I, A-IV, and C-III are expressed in the small intestine and are important in chylomicron formation, secretion, and peripheral lipoprotein metabolism. Also, apo A-IV serves as a satiety signal and antioxidant. We have previously defined patterns of regulation of apolipoprotein expression by dietary lipid in newborn and suckling swine (Pediatr Res 39:1078, 1996; Biochem Biophys Res Commun 221:619, 1996; Am J Physiol 275:G645, 1998). Hypothesis: Intestinal apolipoprotein expression in weanling swine is regulated by type and amount of dietary lipid.

Experimental Design and Methods: Male domestic swine received sow milk for the first 7 days of life and were then weaned onto three isonitrogenous diets over a 3-day period (n=6 for each group): Unsaturated low-fat (ULF) with 3% corn oil, unsaturated high-fat (UHF) with 18% corn oil, and saturated high-fat (SHF) with 15% tallow and 3% corn oil. The ULF diet contained 8% of total calories as lipid, and the UHF and SHF diets contained 41% of calories as lipid. The ULF and UHF diets contained cholesterol at a level found in the SHF diet (16.4 mg/100 g diet). Animals were fed for 3 wks followed by harvest of jejunum. Apo B and A-I mass was measured by ELISA (ng apolipoprotein/µg total protein), since these apolipoproteins may be post-transcriptionally regulated. Apo A-I, A-IV, and C-III mRNA levels were quantitated by RT-PCR (apolipoprotein/β2-microglobulin for apo A-IV and C-III, β-actin for apo A-I mRNA ratios). Results: Weight gain was comparable in all groups (pNS). Results [mean (SEM)]: (Table)

Table 1 No caption available
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Conclusions: Regulation of weanling swine small intestinal apo B and A-I expression is not responsive to dietary lipid. Relative to a low-unsaturated fat diet, jejunal apo A-IV mRNA expression is induced by both saturated and unsaturated fatty acids. However, apo C-III mRNA expression is induced by saturated, but not unsaturated, dietary fatty acids.

Supported by PHS RO1 HD22551 (DDB) and USDA 58-62501-003 and 96-35206-3903 (MAD)