Sc. Nicol et al., NONSHIVERING THERMOGENESIS IN MARSUPIALS - ABSENCE OF THERMOGENIC RESPONSE TO BETA-3-ADRENERGIC AGONISTS, Comparative biochemistry and physiology. Section A: Comparative physiology, 117(3), 1997, pp. 399-405
Citations number
26
Categorie Soggetti
Physiology,Biology
Journal title
Comparative biochemistry and physiology. Section A: Comparative physiology
The status of nonshivering thermogenesis (NST) in marsupials remains c
ontroversial. Although morphological studies have failed to find evide
nce for the presence of brown adipose tissue (BAT) in adults or juveni
les of species from all extant familes of marsupial, a number of studi
es have investigated the metabolic response of marsupials to noradrena
line (NA) and yielded conflicting results. In eutherian mammals, NA st
imulates NST in BAT by acting on beta 3-receptors, and in the experime
nts reported here we investigated the response of adult and juvenile b
rush tail possums (Trichosurus vulpecula), a Brazilian opossum (Monode
lphis domestica), adult and juvenile red-necked (Bennett's) wallabies
(Macropus rufogriseus) and the laboratory rat to selective beta 3-agon
ists (ICI D7114 and BRL 35135) and to NA. Wallabies were tested with t
he beta 3-agonists only. Although NA and both beta 3-agonists caused a
n 85% increase in oxygen consumption in rats, there was no significant
effect on any of the marsupials. These results clearly indicate no be
ta 3-stimulated NST in these marsupials. All reports of metabolic resp
onses to NA are from macropods, and a recent study demonstrates that N
A and other alpha-adrenergic agonists stimulate thermogenesis in a sma
ll macropod, the bettong (Bettongia gaimardi), by acting on alpha 1-re
ceptors. Thermogenic responses to NA seems to be restricted to macropo
ds, showing the danger of characterising the response of any one marsu
pial species as being representative of marsupials as a group. (C) 199
7 Elsevier Science Inc.