Sympathetic activity in brown adipose tissue from rats adapted to a high protein, carbohydrate-free diet

• Published in: Journal of the autonomic nervous system 1998-03, Vol.69 (1), p.1-5
• Main Authors: Brito, Marcia N, Brito, Nilton A, Garófalo, Maria A.R, Kettelhut, Isis C, Migliorini, Renato H
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological - physiology; Adipose Tissue, Brown - innervation; Adipose Tissue, Brown - metabolism; Animals; Biological and medical sciences; Body Temperature Regulation - physiology; Brown adipose tissue; Carbohydrate-free diet; Cold exposure; Cold Temperature; Dietary Carbohydrates - administration & dosage; Dietary Proteins - administration & dosage; Dietary Proteins - pharmacology; Fundamental and applied biological sciences. Psychology; High protein; Male; Norepinephrine - metabolism; Norepinephrine turnover; Rats; Rats, Wistar; Sympathetic Nervous System - physiology; Thermoregulation. Hibernation. Estivation. Ecophysiology and environmental effects; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0165-1838; 1872-7476
• DOI: 10.1016/S0165-1838(97)00132-X

Previous studies have shown that adaptation of rats to a high protein, carbohydrate-free (HP) diet results in a marked reduction in brown adipose tissue (BAT) thermogenic capacity. The present experiments were carried out to assess BAT sympathetic activity in HP diet-adapted rats. It was found that interscapular brown adipose tissue (IBAT) norepinephrine (NE) content, fractional turnover rate and calculated rate of turnover were markedly reduced in HP-fed rats. Replacement of the HP diet by a control, balanced diet for 24 h did not affect BAT NE content significantly, but restored fractional turnover rate and turnover rate values to those of control animals. Exposure to cold (4°) for a short period (8 h) induced a marked increase in IBAT NE fractional turnover rate and calculated turnover rate in both HP and control rats. The cold-induced rise of turnover rate over values at ambient temperature (25°C) was higher in HP rats than in controls. Rectal temperature after 8 h of cold exposure did not differ in HP and control rats. The data suggest that the decreased thermogenic capacity of rats adapted to a high protein, carbohydrate-free diet is due to a reduced sympathetic outflow to BAT, which can be rapidly reactivated by cold stimulation.