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Type: Journal article
Title: Identification of brown fat and mechanisms for energy balance in the marsupial, Sminthopsis crassicaudata
Author: Hope, P.
Pyle, D.
Daniels, C.
Chapman, I.
Horowitz, M.
Morley, J.
Trayhurn, P.
Kumaratilake, J.
Wittert, G.
Citation: American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, 1997; 273(1):R161-R167
Publisher: American Physiological Society
Issue Date: 1997
ISSN: 0363-6119
Statement of
Perdita J. Hope , Diana Pyle , Christopher B. Daniels , Ian Chapman , Michael Horowitz , John E. Morley , Paul Trayhurn , Jaliya Kumaratilake, and Gary Wittert
Abstract: The presence of brown adipose tissue (BAT) in marsupials is controversial because attempts to identify mitochondrial uncoupling protein (UCP) have been unsuccessful. Sminthopsis crassicaudata is a small nocturnal marsupial with an interscapular pad of adipose tissue. Electron microscopy revealed this tissue to have characteristics typical of BAT. GDP binding and UCP detection by immunoblot confirmed BAT. Expression of UCP was increased by cold exposure. When animals were placed from 28 to 15 degrees C, body temperature (Tb) decreased by 1.7 degrees C within 30 min and a further 1.0 degree C by 90 min (P < 0.001) before stabilizing at these lower levels. When animals were returned to 28 degrees C, Tb increased within 30 min (P < 0.001) and returned to basal by 120 min. When animals were maintained at 15 degrees C with ad libitum food for 12 days, Tb (P < 0.05), tail width (P < 0.04), and O2 consumption (P < 0.01) all decreased. The respiratory quotient increased (P < 0.001), indicating a change from fat to carbohydrate utilization. Food intake was unchanged, and body weight increased on day 1 (P < 0.01) before returning to baseline on day 3, remaining stable thereafter. These data suggest that although BAT is present in the marsupial S. crassicaudata, it may not be necessary for thermogenesis, at least in the short term. S. crassicaudata utilizes a plasticity in Tb and a change in substrate utilization to maintain energy balance and body composition without the need for an increase in metabolic rate or food consumption and without the need for torpor.
Keywords: Mitochondria
Body Weight
Carrier Proteins
Ion Channels
Membrane Proteins
Mitochondrial Proteins
Guanosine Diphosphate
Microscopy, Electron
Feeding Behavior
Energy Metabolism
Oxygen Consumption
Body Temperature Regulation
Models, Biological
Adipose Tissue, Brown
Cold Temperature
Uncoupling Protein 1
Rights: Copyright © 1997 the American Physiological Society
DOI: 10.1152/ajpregu.1997.273.1.r161
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Appears in Collections:Anatomical Sciences publications
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