Tsukazaki K, Nikami H, Shimizu Y, Kawada T, Yoshida T, Saito M
Department of Biochemistry, Faculty of Veterinary Medicine, Hokkaido University, Sapporo.
J Biochem. 1995 Jan;117(1):96-100. doi: 10.1093/oxfordjournals.jbchem.a124728.
When mammals are exposed to a cold environment for a long time, the capacity of nonshivering thermogenesis by brown adipose tissue (BAT) increases in association with the stimulation of synthesis of some specific proteins and tissue hyperplasia, which are totally dependent on sympathetic innervation to this tissue. To clarify the roles of the adrenergic mechanisms for the cold-induced protein synthesis and hyperplasia in BAT, in this study, the effects of chronic treatment with adrenergic agonists using an osmotic mini-pump were examined in rats. Continuous administration of noradrenaline or isoproterenol (beta-agonist) for 10 days resulted in increased synthesis of the mitochondrial uncoupling protein and an isoform of glucose transporter (GLUT4), and tissue hyperplasia, in the same way as after cold exposure of the same duration. Phenylephrine (alpha-agonist) administration did not have any significant effect. Surgical sympathetic denervation completely abolished the effects of cold exposure, whereas it did not influence those of adrenergic agonists at all. These results indicate that the stimulative effects of cold exposure on protein synthesis and hyperplasia of BAT are attributable solely to the beta-adrenergic action of noradrenaline secreted from the sympathetic nerves in this tissue.
当哺乳动物长时间暴露于寒冷环境时，棕色脂肪组织（BAT）的非寒战产热能力会随着某些特定蛋白质合成的刺激和组织增生而增加，而这完全依赖于该组织的交感神经支配。为了阐明肾上腺素能机制在BAT冷诱导的蛋白质合成和增生中的作用，在本研究中，我们在大鼠中检测了使用渗透微型泵长期给予肾上腺素能激动剂的效果。连续10天给予去甲肾上腺素或异丙肾上腺素（β-激动剂）会导致线粒体解偶联蛋白和葡萄糖转运蛋白（GLUT4）的一种同工型的合成增加以及组织增生，与相同持续时间的冷暴露后的情况相同。给予去氧肾上腺素（α-激动剂）没有任何显著影响。手术切断交感神经完全消除了冷暴露的影响，而对肾上腺素能激动剂的影响则完全没有影响。这些结果表明，冷暴露对BAT蛋白质合成和增生的刺激作用完全归因于该组织中交感神经分泌的去甲肾上腺素的β-肾上腺素能作用。
