AJP - Endocrinology and Metabolism, Vol 250, Issue 4 362-E366, Copyright © 1986 by American Physiological Society
Thermogenesis and sympathetic activity in BAT of overfed rats after adrenalectomy
D. Marchington, N. J. Rothwell, M. J. Stock and D. A. York
Resting oxygen consumption was elevated by 30% in young rats fed a
cafeteria diet compared with their chow-fed controls and by 22% in
cafeteria-fed, adrenalectomized (ADX) rats compared with the ADX chow-fed
group, but injection of propranolol reduced oxygen consumption in the
cafeteria-fed animals and abolished these differences. Brown adipose tissue
(BAT) mass was increased by cafeteria feeding, and the activity of the
mitochondrial proton conductance pathway (assessed from purine nucleotide
binding) was enhanced by adrenalectomy and by cafeteria feeding.
Norepinephrine turnover in BAT (determined from the time-dependent loss of
tissue [3H]norepinephrine specific activity) was increased by 105% in
sham-operated, cafeteria-fed rats, by 142% in chow-fed ADX rats, and by
400% in cafeteria-fed ADX rats, compared with chow-fed controls. Cardiac
norepinephrine turnover was elevated by 80% in sham-operated, cafeteria-fed
rats, but unaffected by adrenalectomy. These data indicate that the
enhanced thermogenesis and BAT activity induced by adrenalectomy in chow-
or cafeteria-fed rats is due to increased sympathetic activity in the
tissue.
