The role of insulin in norepinephrine turnover and thermogenesis in brown adipose tissue after acute cold-exposure.
The role of insulin in norepinephrine turnover (NE) and thermogenesis in brown adipose tissue (BAT) after acute cold-exposure was studied using streptozocin (STZ)-induced diabetic rats. NE turnover was estimated by the NE synthesis inhibition technique with alpha-methyl-p-tyrosine. BAT thermogenesis was estimated by measuring mitochondrial guanosine-5'-diphosphate (GDP), cytochrome oxidase activity and mitochondrial oxygen consumption in BAT at an ambient temperature of 22 degrees C and during a six-hour cold-exposure at 4 degrees C. In insulin-deficient diabetic rats, the NE turnover, mitochondrial GDP binding, cytochrome oxidase activity and mitochondrial oxygen consumption in BAT at 22 degrees C were significantly reduced, compared with those of control rats. Treatment of STZ-induced diabetic rats with insulin prevented a decrease in NE turnover and BAT thermogenesis. Acute cold-exposure increased the NE turnover of BAT in insulin-deficient diabetic rats. The BAT thermogenic response to acute cold-exposure, however, did not occur in insulin-deficient diabetic rats. These results suggest that insulin is not essential in potentiating NE turnover in BAT after acute cold-exposure, but is required for cold-induced thermogenesis.
Yoshioka
K
K
First Department of Internal Medicine and Biochemistry, Kyoto Prefectural University of Medicine, Japan.
Yoshida
T
T
Wakabayashi
Y
Y
Nishioka
H
H
Kondo
M
M
D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000818:Animals; D001833:Body Temperature Regulation / Q000502:physiology*; D003080:Cold Temperature; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism / Q000503:physiopathology; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D006153:Guanosine Diphosphate / Q000378:metabolism; D007328:Insulin / Q000502:physiology* / Q000627:therapeutic use; D008928:Mitochondria / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013564:Sympathetic Nervous System / Q000502:physiology
D007328:Insulin; D006153:Guanosine Diphosphate; D003576:Electron Transport Complex IV; D009638:Norepinephrine