Paradoxical effects of exogenous norepinephrine on cold-induced thermogenesis in the rat.
The effect of norepinephrine (NE, 250 microgram/kg IP) on thermoregulatory behavior of rats in a cold environment was tested. Norepinephrine produced an increase in operant responding for heat reward but a decrease in core temperature. Since animals compensate behaviorally for alterations in autonomic thermoregulation, this suggested that NE might inhibit cold-induced thermogenesis, an effect contrary to the expected action of this agent. A second experiment showed that NE increased oxygen consumption when rats were tested at 25 degrees C as expected, but decreased oxygen consumption when tested at 5 degrees C. The beta-adrenoceptor antagonist propranolol decreased oxygen consumption both at 25 and at 5 degrees C as expected. These results suggest that the thermogenic effect of NE is highly dependent on ambient temperature.
Zylan
K D
KD
Department of Psychology, University of California, Santa Barbara 93106.
Carlisle
H J
HJ
D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects*; D003080:Cold Temperature; D003216:Conditioning, Operant / Q000187:drug effects; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D011433:Propranolol; D009638:Norepinephrine