Dietary obesity and neonatal sympathectomy. II. Thermoregulation and brown adipose metabolism.
Neonatal sympathectomy with guanethidine (50 mg/kg for 3 wk) in Sprague-Dawley rats was previously shown not to significantly affect body weight gain, even when rats were raised in small litters and fed a high-calorie diet from weaning to produce diet-induced obesity (15). In our study rectal temperatures of cold-stressed (24 h at 4 degrees C) sympathectomized rats (obese and lean) fell only 1.4 degrees C after 4 h and were normal by 24 h, as were plasma catecholamine, glycerol glucose, and insulin levels after 4 h at 4 degrees C. Obese rats (with or without sympathectomy) had decreased 4-h (at 4 degrees C) plasma norepinephrine (NE) and increased basal and 4-h plasma glycerol, glucose, and insulin levels. Despite greater than 95% depletion of interscapular brown adipose tissue (IBAT) NE in sympathectomized rats, there was no alteration in beta-adrenoreceptor binding and only 10 and 32% decreases in basal and maximal NE-stimulated O2 consumption, respectively. Obese rats had significant increases in IBAT beta-receptor binding (148-190%/cell, 77-155%/pad) and in basal (11-19%) but not maximal O2 consumption. These results suggest that factors other than the sympathetic nervous system can effectively control thermoregulation, IBAT metabolism, and body weight in the presence of a chronic defect in sympathetic function.
D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001833:Body Temperature Regulation; D003080:Cold Temperature; D004032:Diet / Q000009:adverse effects*; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D009765:Obesity / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D010101:Oxygen Consumption; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D013312:Stress, Physiological / Q000503:physiopathology; D013563:Sympathectomy, Chemical
D011943:Receptors, Adrenergic, beta; D009638:Norepinephrine