title: Long-term high-fat feeding induces greater fat storage in mice lacking UCP3.
abstract: Uncoupling protein-3 (UCP3) is a mitochondrial inner-membrane protein highly expressed in skeletal muscle. While UCP3's function is still unknown, it has been hypothesized to act as a fatty acid (FA) anion exporter, protecting mitochondria against lipid peroxidation and/or facilitating FA oxidation. The aim of this study was to determine the effects of long-term feeding of a 45% fat diet on whole body indicators of muscle metabolism in congenic C57BL/6 mice that were either lacking UCP3 (Ucp3(-/-)) or had a transgenically induced approximately twofold increase in UCP3 levels (UCP3tg). Mice were fed the high-fat (HF) diet for a period of either 4 or 8 mo immediately following weaning. After long-term HF feeding, UCP3tg mice weighed an average of 15% less than wild-type mice (P < 0.05) and were 20% less metabolically efficient than both wild-type and Ucp3(-/-) mice (P < 0.01). Additionally, wild-type mice had 21% lower, whereas UCP3tg mice had 36% lower, levels of adiposity compared with Ucp3(-/-) mice (P < 0.05 and P < 0.001, respectively), indicating a protective effect of UCP3 against fat gain. No differences in whole body oxygen consumption were detected following long-term HF feeding. Glucose and insulin tolerance tests revealed that both the UCP3tg and Ucp3(-/-) mice were more glucose tolerant and insulin sensitive compared with wild-type mice after short-term HF feeding, but this protection was not maintained in the long term. Findings indicate that UCP3 is involved in protection from fat gain induced by long-term HF feeding, but not in protection from insulin resistance.
authors: Faculty of Medicine, Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada.
authors: Sheila R
authors: SR
authors: Costford
authors: Shehla N
authors: SN
authors: Chaudhry
authors: Sean A
authors: SA
authors: Crawford
authors: Mahmoud
authors: M
authors: Salkhordeh
authors: Mary-Ellen
authors: ME
authors: Harper
mesh_terms: D052436:Adipose Tissue, White / Q000033:anatomy & histology / Q000187:drug effects*; D000825:Animal Structures / Q000033:anatomy & histology / Q000187:drug effects; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects; D004734:Energy Metabolism / Q000187:drug effects; D004822:Epididymis / Q000033:anatomy & histology; D005951:Glucose Tolerance Test; D007333:Insulin Resistance; D007473:Ion Channels / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D013997:Time Factors; D000071247:Uncoupling Protein 3
chemical_list: D001786:Blood Glucose; D004041:Dietary Fats; D007473:Ion Channels; D024101:Mitochondrial Proteins; C000604393:Ucp3 protein, mouse; D000071247:Uncoupling Protein 3