The Tasmanian bettong (Bettongia gaimardi) is a small marsupial able to increase its metabolic rate by non-shivering thermogenesis. Oxygen consumption increases in response to various stimuli: vasopressin, non-epinephrine, both α1 and β adrenergic stimulation, thyroid hormone and cold-acclimation (CA)(4-5°C for 14 days). Moreover, the metabolic rate response to nor-epinephrine is enhanced after CA (71% increase ‘v’ 47% prior to CA). The ability to respond to these stimuli only appears after week 10 of the 15-week pouch life. We have attempted to locate the source and cause of the metabolic response. Brown adipose tissue (BAT) is totally absent in this species as in most marsupials. In addition, we have failed to locate the uncoupling protein (UCP1) associated with BAT. Our research led us to investigate skeletal muscle as a source of heat production in this species and we have located both UCP2 and UCP 3 in this tissue in cold-acclimated bettongs.
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