Expression of glycerokinase in brown adipose tissue is stimulated by the sympathetic nervose system.
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Date
2003
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Abstract
Expression of glycerokinase
in brown adipose tissue is stimulated by the sympathetic
nervous system. Am J Physiol Regul Integr Comp Physiol 284:
R1536–R1541, 2003; 10.1152/ajpregu.00764.2002.—The effect
of cold exposure (4°C) or prolonged norepinephrine infusion
on the activity and mRNA levels of glycerokinase (GyK) was
investigated in rat interscapular brown adipose tissue (BAT).
Cold exposure for 12 and 24 h induced increases of 30% and
100%, respectively, in the activity of BAT GyK, which was
paralleled by twofold and fourfold increase in enzyme mRNA
levels. BAT hemidenervation resulted in reductions of 50%
and 30% in GyK activity and in mRNA levels, respectively, in
denervated pads from rats kept at 25°C, and suppressed in
these pads the cold-induced increases in both GyK activity
and mRNA levels. The increase in GyK activity induced by
cold exposure was not affected by phenoxybenzamine, but
was markedly inhibited by previous administration of propranolol
or actinomycin D. BAT GyK activity did not change
significantly after 6 h of continuous subcutaneous infusion of
norepinephrine (20 g/h), but increased twofold and fourfold
after 12 and 24 h, with no further increase after 72 h of
infusion. Norepinephrine infusion also activated mRNA production,
but the effect was comparatively smaller than that
on enzyme activity. -Adrenergic agonists also stimulated
GyK activity with the following relative magnitude of response:
CL316243 ( 3) isoproterenol (non-selective) dobutamine
( 1). In vitro rates of incorporation of glycerol into
glyceride-glycerol were increased in BAT from rats exposed
to cold. The data suggest that in conditions of a sustained
increase in BAT sympathetic flow there is a stimulation of
GyK gene expression at the pretranslational level, with increased
enzyme activity, mediated by -adrenoreceptors,
mainly 3.
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Keywords
Cold exposure, Norepinephrine infusion, Agonists and antagonists, Actinomycin D, Glyceride-glycerol synthesis
Citation
FESTUCCIA, W. T. L. et al. Expression of glycerokinase in brown adipose tissue is stimulated by the sympathetic nervose system. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology , v. 284, p. R1536-R1541, 2003. Disponível em: <http://ajpregu.physiology.org/content/284/6/R1536.long>. Acesso em: 19 fev. 2017.