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Noradrenaline‐Induced Lipolysis in Adipose Tissue is Suppressed at Hibernation Temperatures in Ground Squirrels
Author(s) -
Dark J.,
Miller D. R.,
Lewis D. A.,
Fried S. K.,
Bunkin D.
Publication year - 2003
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1046/j.1365-2826.2003.01020.x
Subject(s) - lipolysis , torpor , medicine , endocrinology , hibernation (computing) , white adipose tissue , brown adipose tissue , adipose tissue , ground squirrel , norepinephrine , chemistry , biology , thermoregulation , dopamine , state (computer science) , algorithm , computer science
Responsiveness of white adipose tissue (WAT) and brown adipose tissue (BAT) from hibernating and nonhibernating golden‐mantled ground squirrels ( Spermophilus lateralis ) to the lipolytic action of the sympathetic neurotransmitter, noradrenaline, was tested in vitro at temperatures characteristic of deep torpor (5 °C) and euthermia (37 °C). Noradrenaline‐stimulated lipolysis, as indicated by WAT glycerol release, of tissue from hibernating ground squirrels was six‐ to ten‐fold greater at 37 °C than at 5 °C. Noradrenaline was ineffective in increasing lipolysis at 5 °C. Noradrenaline‐stimulated lipolysis in BAT was similarly suppressed at 5 °C. Noradrenaline‐stimulated lipolysis was little affected by temperature change below approximately 15 °C but strongly correlated with temperature above approximately 15 °C. Noradrenaline‐induced lipolysis of WAT from nonhibernating and hibernating ground squirrels did not differ at an incubation temperature of 5 °C. We conclude that noradrenaline‐stimulated WAT lipolytic activity is markedly suppressed at the low temperatures characteristic of deep torpor and that there is no ‘hibernation‐specific’ adaptation of WAT to enhance its responsiveness to noradrenaline at low tissue temperatures. Temperature dependence of noradrenaline‐stimulated lipolysis may in part account for the shift from lipid to carbohydrate metabolism during the earliest stage of arousal from deep torpor.