Brown fat thermogenesis and its role in the development of obesity

Barbara J. Moore, Barbara A Horwitz, Judith S. Stern

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Abstract

The role of brown fat thermogenesis in the development of obesity is considered from a number of perspectives. In adult rats, the impact of scapular brown fat lipectomy on carcass fat accretion was examined in three different rodent models: the Zucker lean (Fa/-) rat which is relatively resistant to obesity, the Zucker obese (fa/fa) rat which is characterized by a particularly severe form of hyperplastic obesity and the Osborne Mendel rat which remains lean on a standard pelleted diet but readily becomes obese on a palatable high fat diet. The consequences of brown fat lipectomy varied from no effect on carcass white fat accretion in Zucker Fa/- lean rats to a significant increase in adiposity in the Zucker fatty fa/fa relative to their respective sham-operated controls. The effect of the Osborne Mendel rat was intermediate between the Fa/- and the fa/fa. The results point to the importance of genetic background with respect to the impact of brown fat lipectomy on the development of white fat adiposity. In the developing Zucker rat at 2 and 8 days of age, in vivo evidence is presented to support the concept that brown fat thermogenesis is attenuated in the fatty fa/fa preobese pup. In animals of the fatty fa/fa genotype, maximum oxygen consumption in response to acute cold exposure was lower than in lean pups of the Fa/Fa genotype. Moreover, at 8 days of age, the rectal temperature of the cold-exposed fa/fa pups fell more precipitously than did that of the lean during the period of cold exposure. The genetic obesity of the fatty fa/fa rat at 8 days of age was contrasted with that of 8-day old Zucker genetically lean Fa/Fa pups raised in small litters, a manipulation that results in a type of dietary obesity. The rate of oxygen consumption in response to cold was significantly increased in the overfed pups as compared to both genetically obese (fa/fa) pups and genetically lean (Fa/Fa) pups raised in normal sized litters. Our data support the concept that although the obesity of the fatty fa/fa rat pup was associated with a failure of brown fat mediated thermogenesis, there appeared to be no such failure in the overfed Fa/Fa lean pups during the initial phase of overfeeding.

Original languageEnglish (US)
Pages (from-to)577-583
Number of pages7
JournalBrain Research Bulletin
Volume14
Issue number6
DOIs
StatePublished - 1985

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Keywords

  • Brown fat
  • Energy expenditure
  • Lipectomy
  • Obesity
  • Oxygen consumption
  • Thermogenesis
  • Zucker rat

ASJC Scopus subject areas

  • Neuroscience(all)

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