TY - JOUR
T1 - Identification of brown fat and mechanisms for energy balance in the marsupial, Sminthopsis crassicaudata
AU - Hope, Perdita J.
AU - Pyle, Diana
AU - Daniels, Christopher B.
AU - Chapman, Ian
AU - Horowitz, Michael
AU - Morley, John E.
AU - Trayhurn, Paul
AU - Kumaratilake, Jaliya
AU - Wittert, Gary
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 1997/7
Y1 - 1997/7
N2 - 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°C, body temperature (T(b)) decreased by 1.7°C within 30 min and a further 1.0°C by 90 min (P < 0.001) before stabilizing at these lower levels. When animals were returned to 28°C, T(b) increased within 30 min (P < 0.001) and returned to basal by 120 min. When animals were maintained at 15°C with ad libitum food for 12 days, T(b) (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 T(b) 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.
AB - 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°C, body temperature (T(b)) decreased by 1.7°C within 30 min and a further 1.0°C by 90 min (P < 0.001) before stabilizing at these lower levels. When animals were returned to 28°C, T(b) increased within 30 min (P < 0.001) and returned to basal by 120 min. When animals were maintained at 15°C with ad libitum food for 12 days, T(b) (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 T(b) 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.
KW - Brown adipose tissue
KW - Respiratory quotient
KW - Thermogenesis
KW - Uncoupling protein
UR - http://www.scopus.com/inward/record.url?scp=0030740510&partnerID=8YFLogxK
U2 - 10.1152/ajpregu.1997.273.1.r161
DO - 10.1152/ajpregu.1997.273.1.r161
M3 - Article
C2 - 9249545
AN - SCOPUS:0030740510
SN - 0363-6119
VL - 273
SP - R161-R167
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 1 42-1
ER -