title: A high-fat diet rich in corn oil reduces spontaneous locomotor activity and induces insulin resistance in mice.
abstract: Over the last few decades, polyunsaturated fatty acid (PUFA), especially n-6 PUFA, and monounsaturated fatty acid content in 'Western diets' has increased manyfold. Such a dietary shift also parallels rising sedentary behavior and diabetes in the Western world. We queried if a shift in dietary fats could be linked to physical inactivity and insulin insensitivity in mice. Eight-week old female C57/Bl6 mice were fed either high-fat (HF) diets [40% energy corn oil (CO) or isocaloric olive oil (OO) diets] or chow (n=10/group) for 6 weeks, followed by estimation of spontaneous locomotor activity, body composition and in vivo metabolic outcomes. Although lean mass and resting energy expenditure stayed similar in both OO- and CO-fed mice, only CO-fed mice demonstrated reduced spontaneous locomotor activity. Such depressed activity in CO-fed mice was accompanied by a lower respiratory ratio, hyperinsulinemia and impaired glucose disposal following intraperitoneal glucose tolerance and insulin tolerance tests compared to OO-fed mice. Unlike the liver, where both HF diets increased expression of fat oxidation genes like PPARs, the skeletal muscle of CO-fed mice failed to up-regulate such genes, thereby supporting the metabolic insufficiencies observed in these mice. In summary, this study demonstrates a specific contribution of n-6 PUFA-rich oils like CO to the loss of spontaneous physical activity and insulin sensitivity in mice. If these data hold true for humans, this study could provide a novel link between recent increases in dietary n-6 PUFA to sedentary behavior and the development of insulin resistance in the Western world.
authors.affiliation: Department of Medical Genetics, University of British Columbia, University of British Columbia, Vancouver, Canada.
authors.forename: Chi Kin
authors.initials: CK
authors.lastname: Wong
authors.affiliation: Department of Biology, IKBSAS, University of British Columbia-Okanagan, Canada.
authors.forename: Amy
authors.initials: A
authors.lastname: Botta
authors.affiliation: Department of Biology, IKBSAS, University of British Columbia-Okanagan, Canada.
authors.forename: Jason
authors.initials: J
authors.lastname: Pither
authors.affiliation: Department of Biology, IKBSAS, University of British Columbia-Okanagan, Canada.
authors.forename: Chuanbin
authors.initials: C
authors.lastname: Dai
authors.affiliation: Department of Medical Genetics, University of British Columbia, University of British Columbia, Vancouver, Canada.
authors.forename: William T
authors.initials: WT
authors.lastname: Gibson
authors.affiliation: Department of Biology, IKBSAS, University of British Columbia-Okanagan, Canada. Electronic address: sanjoy.ghosh@ubc.ca.
authors.forename: Sanjoy
authors.initials: S
authors.lastname: Ghosh
mesh_terms: D000818:Animals; D003314:Corn Oil / Q000008:administration & dosage / Q000009:adverse effects*; D059305:Diet, High-Fat / Q000009:adverse effects*; D004041:Dietary Fats / Q000008:administration & dosage / Q000009:adverse effects*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D043371:Fatty Acids, Omega-6 / Q000008:administration & dosage / Q000009:adverse effects; D005260:Female; D005951:Glucose Tolerance Test; D006946:Hyperinsulinism / Q000097:blood; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D051379:Mice; D008810:Mice, Inbred C57BL; D009043:Motor Activity; D000069463:Olive Oil / Q000008:administration & dosage; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014280:Triglycerides / Q000097:blood
chemical_list: D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D043371:Fatty Acids, Omega-6; D007328:Insulin; D000069463:Olive Oil; D012333:RNA, Messenger; D014280:Triglycerides; D003314:Corn Oil
keywords: Corn oil; Diabetes; Exercise; Insulin resistance; Locomotor activity; MUFA; Polyunsaturated fatty acids; n-6 PUFA