Background: Long-chain polyunsaturated fatty acids (LCPUFA) are important in the development of the immature nervous system, and addition of these fatty acids to infant formula has been proposed. However, the effects of LCPUFA on small intestinal apolipoprotein (apo) secretion in the neonate have not been studied. Purpose: To determine the effect of LCPUFA on apo B and A-I secretion in a newborn swine intestinal epithelial cell line(IPEC-1). Methods: Differentiated IPEC-1 cells were prepared on collagen-coated filters in Transwell culture dishes in serum-free medium. Cells were incubated for 24 hrs with docosahexaenoic acid (DHA, 22:6) or eicosapentaenoic acid (EPA, 20:5) complexed with albumin (4:1 molar ratio) at a fatty acid concentration of 0.8 mM, or albumin alone (control), added to the apical medium. N=4-6 wells/group. After incubation, cells and basolateral medium were harvested for measurement of apo B and A-I mass by ELISA and cell homogenate total protein. Results: Cell apo content was expressed asμg/mg cell protein, and apo secretion was expressed as μg/mg cell protein/24 hr. Values are expressed as mean (SEM) in the table below (*different from control at p<0.05). Medium lactate dehydrogenase was measured as an index of cellular injury and was not different in any of the groups. Conclusions: Both DHA and EPA decreased apo B secretion and increased apo A-I secretion in IPEC-1 cells. Speculation: Since apo B is obligate for triglyceride-rich lipoprotein assembly and secretion, this decrease in apo B secretion induced by LCPUFA may adversely affect lipid absorption. The increase in apo A-I secretion may increase high-density lipoprotein levels and thereby enhance reverse cholesterol transport in the neonate.

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