Brown fat is essential for cold-induced thermogenesis but not for obesity resistance in aP2-Ucp mice.
The role of brown adipose tissue in total energy balance and cold-induced thermogenesis was studied. Mice expressing mitochondrial uncoupling protein 1 (UCP-1) from the fat-specific aP2 gene promoter (heterozygous and homozygous aP2-Ucp transgenic mice) and their nontransgenic C57BL6/J littermates were used. The transgenic animals are resistant to obesity induced by a high-fat diet, presumably due to ectopic synthesis of UCP-1 in white fat. These animals exhibited atrophy of brown adipose tissue, as indicated by smaller size of brown fat and reduction of its total UCP-1 and DNA contents. Norepinephrine-induced respiration (measured in pentobarbital sodium-anesthetized animals) was decreased proportionally to the dosage of the transgene, and the homozygous (but not heterozygous) transgenic mice exhibited a reduction in their capacity to maintain body temperature in the cold. Our results indicate that the role of brown fat in cold-induced thermogenesis cannot be substituted by increased energy expenditure in other tissues.
Stefl
B
B
Faculty of Sciences, Charles University, Prague, Czech Republic.
Janovská
A
A
Hodný
Z
Z
Rossmeisl
M
M
Horáková
M
M
Syrový
I
I
Bémová
J
J
Bendlová
B
B
Kopecký
J
J
D000273:Adipose Tissue / Q000502:physiology; D002001:Adipose Tissue, Brown / Q000502:physiology*; D000818:Animals; D001833:Body Temperature Regulation / Q000235:genetics / Q000502:physiology*; D001835:Body Weight; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D003080:Cold Temperature; D004734:Energy Metabolism; D006720:Homozygote; D007113:Immunity, Innate / Q000235:genetics; D007473:Ion Channels; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D026901:Membrane Transport Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D024101:Mitochondrial Proteins; D009765:Obesity / Q000235:genetics / Q000503:physiopathology*; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000235:genetics / Q000502:physiology; D013961:Thyroid Gland / Q000502:physiology; D019076:Transgenes; D000071256:Uncoupling Protein 1; D000071246:Uncoupling Protein 2
D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; C000604372:Ucp1 protein, mouse; D000071256:Uncoupling Protein 1; D000071246:Uncoupling Protein 2