Brown fat and nonshivering thermogenesis in the gray mouse lemur (Microcebus murinus).
The gray mouse lemur Microcebus murinus is a rare example of a primate exhibiting daily torpor. In captive animals, we examined the metabolic rate during arousal from torpor and showed that this process involved nonshivering thermogenesis (NST). Under thermoneutrality (28 degrees C), warming-up from daily torpor (body temperature <33 degrees C) involved a rapid (<5 min) increase of O(2) consumption that was proportional to the depth of torpor (n = 8). The injection of a beta-adrenergic agonist (isoproterenol) known to elicit NST induced a dose-dependent increase in metabolic rate (n = 8). Moreover, maximum thermogenesis was increased by cold exposure. For the first time in this species, anatomic and histological examination using an antibody against uncoupling protein (UCP) specifically demonstrated the presence of brown fat. With the use of Western blotting with the same antibody, we showed a likely increase in UCP expression after cold exposure, suggesting that NST is also used to survive low ambient temperatures in this tropical species.
Génin
F
F
Centre National de la Recherche Scientifique Unité Mixte de Recherches 8571, Muséum National d'Histoire Naturelle, Laboratoire d'Ecologie Générale, F-91800 Brunoy, France. fabien.genin@free.fr
Nibbelink
M
M
Galand
M
M
Perret
M
M
Ambid
L
L
D002001:Adipose Tissue, Brown / Q000166:cytology / Q000502:physiology*; D000818:Animals; D001143:Arousal / Q000502:physiology; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism; D016565:Cheirogaleidae / Q000502:physiology*; D002940:Circadian Rhythm; D005260:Female; D007267:Injections; D007473:Ion Channels; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008660:Metabolism / Q000187:drug effects; D024101:Mitochondrial Proteins; D010101:Oxygen Consumption; D012894:Sleep Stages / Q000502:physiology; D022722:Thermogenesis / Q000502:physiology*; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D000071256:Uncoupling Protein 1; D007545:Isoproterenol