title: Alterations of brown adipose tissue in genetically obese (ob/ob) mice. I. Demonstration of loss of metabolic response to nerve stimulation and catecholamines and its partial recovery after fasting or cold adaptation.
abstract: Metabolic responses to electrical nerve stimulation or norepinephrine of isolated interscapular brown adipose tissue (BAT) from lean and ob/ob mice were studied using either continuous monitoring of the NAD(P)H/NAD(P) redox state or direct microcalorimetry. The responses to these sympathetic stimuli were not significantly different from zero in BAT of ob/ob mice kept at 22 C and fed ad libitum. The metabolic rate of BAT of lean mice was stimulated 3-fold by norepinephrine. ob/ob mice are hyperglycemic and hyperinsulinemic; cold adaptation further increased their plasma glucose, and fasting decreased the levels of both glucose and insulin to normal values. Both fasting and cold adaptation at 5 C partially restored the tissue metabolic response of ob/ob mice, whereas a decreased sensitivity was observed in the tissue of lean mice. The results of these experiments are compatible with the hypothesis that the impaired capacity of BAT of ob/ob mice to produce heat could be one of the causes of their high food efficiency and their inability to withstand acute cold exposure.
mesh_terms: D000064:Acclimatization; D002001:Adipose Tissue, Brown / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001833:Body Temperature Regulation; D002395:Catecholamines / Q000494:pharmacology*; D003080:Cold Temperature; D004558:Electric Stimulation; D005215:Fasting; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology
chemical_list: D002395:Catecholamines; D009243:NAD; D009638:Norepinephrine