Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on thermogenesis in brown adipose tissue of rats.
Male Sprague-Dawley rats were treated with a usually lethal dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 125 micrograms/kg i.p. in corn oil) or with vehicle alone. Two, 4, and 8 days after treatment the temperature of interscapular brown adipose tissue (IBAT) was monitored during venous infusion of norepinephrine (480 ng/min) for 60 min. The temperature response was about 1.0-1.5 degrees C within 1 h in vehicle-treated, pair-fed and ad libitum-fed controls. In TCDD-treated animals, the response of IBAT decreased with time after TCDD dosage, amounting to only 0.3 +/- 0.1 degree C at 8 days after dosing (differences significant with respect to both controls, P less than 0.05). GDP binding to IBAT mitochondria (a measure of thermogenic capacity) was unchanged in all groups, indicating that the reduced thermogenic response was probably not caused by an impairment of the mitochondrial uncoupling process by TCDD.
Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City 66103.
L W
LW
Weber
T W
TW
Haart
K
K
Rozman
D002001:Adipose Tissue, Brown / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D004147:Dioxins / Q000633:toxicity*; D004435:Eating / Q000187:drug effects; D006153:Guanosine Diphosphate / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains
D004147:Dioxins; D000072317:Polychlorinated Dibenzodioxins; D006153:Guanosine Diphosphate; D009638:Norepinephrine