title: An isocaloric PUFA diet enhances lipid uptake and weight gain in aging rats.
abstract: Aging is associated with a change in the morphology and absorptive capacity of the small intestine. In young rats, feeding a semisynthetic diet containing saturated FA (SFA) increases nutrient uptake, as compared with an isocaloric diet containing polyunsaturated FA (PUFA). We tested the hypotheses that (i) aging is associated with a decline in lipid absorption in the Fischer 344 rat; (ii) this decline can be corrected by manipulating the fat composition of the diet; and (iii) the age- and diet-associated variations in lipid uptake are associated with changes in the ileal lipid-binding protein (ILBP) or the intestinal or liver FA-binding proteins (I- or L-FABP, respectively) in the cytosol of the enterocyte. In rats fed SFA or PUFA, aging was associated with a decline in the in vitro uptake of stearic acid (18:0) when expressed on the basis of intestinal or mucosal weight. In contrast, age had no effect on lipid uptake when expressed on the basis of serosal surface area, whereas lipid uptake increased with age when expressed on the basis of mucosal surface area. The age-associated variations in lipid uptake were not associated with changes in protein abundance and/or expression of ILBP, I-FABP, or L-FABP. In 24-mon-old rats, when uptake of lipids was expressed on the basis of mucosal surface area, feeding PUFA enhanced lipid uptake and body weight gain as compared with rats fed SFA. Future studies must determine whether the enhanced lipid uptake and body weight gain observed in older animals fed PUFA have any therapeutic benefit.
authors.affiliation: Nutrition and Metabolism Group, Division of Gastroenterology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Trudy D
authors.initials: TD
authors.lastname: Woudstra
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Drozdowski
authors.forename: Gary E
authors.initials: GE
authors.lastname: Wild
authors.forename: M T
authors.initials: MT
authors.lastname: Clandinin
authors.forename: Luis B
authors.initials: LB
authors.lastname: Agellon
authors.forename: Alan B R
authors.initials: AB
authors.lastname: Thomson
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D000818:Animals; D001835:Body Weight; D002352:Carrier Proteins / Q000378:metabolism; D004032:Diet; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage / Q000378:metabolism*; D050556:Fatty Acid-Binding Proteins; D006801:Humans; D007082:Ileum / Q000166:cytology / Q000378:metabolism; D007583:Jejunum / Q000378:metabolism; D050356:Lipid Metabolism; D008297:Male; D008875:Middle Aged; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D002352:Carrier Proteins; D004042:Dietary Fats, Unsaturated; C493319:FABP1 protein, human; C493321:Fabp1 protein, rat; D050556:Fatty Acid-Binding Proteins