Desautels M, Beard A P, Rawlings N C
Department of Physiology, College of Medicine, University of Saskatchewan, Health Sciences Building, Saskatoon, Canada.
Can J Physiol Pharmacol. 1995 Oct;73(10):1458-65. doi: 10.1139/y95-203.
Richardson ground squirrels are hibernators with seasonal changes in the thermogenic capacity of brown adipose tissue (BAT). The objective of this work was to evaluate whether norepinephrine (NE) acts both as a thermogenic and a growth factor in BAT. Brown adipocytes were isolated by collagenase digestion of axillary BAT and kept in a tissue culture incubator in methionine-free Dulbecco's modified Eagle's medium supplemented with albumin, antibiotics, and calf serum with or without NE for up to 24 h. For short-term incubations (<6 h), calf serum was omitted. Freshly isolated brown adipocytes responded to NE with 10- to 20-fold increases in rates of oxygen uptake. This ability to respond calorigenically to NE was maintained over a 24-h period. However, no significant increase in [35S]methionine incorporation into cellular proteins was observed when brown adipocytes were incubated for 1-6 or 24 h with NE. When labeled cell proteins were separated by SDS-PAGE and visualized by autoradiography, no selective change in protein labeling, particularly in the uncoupling protein (32 kDa) region was observed. Likewise, [35S]methionine incorporation into immunoprecipitable uncoupling protein was not affected by the presence of NE. These results suggest a dissociation between the thermogenic and growth effects of NE in BAT of Richardson ground squirrels.
理查森地松鼠是冬眠动物，其褐色脂肪组织（BAT）的产热能力会随季节变化。这项工作的目的是评估去甲肾上腺素（NE）在BAT中是否既作为产热因子又作为生长因子发挥作用。通过胶原酶消化腋窝BAT分离出褐色脂肪细胞，并将其置于组织培养箱中，在不含蛋氨酸的杜氏改良 Eagle 培养基中培养，该培养基添加了白蛋白、抗生素和小牛血清，添加或不添加NE，培养长达24小时。对于短期培养（<6小时），省略小牛血清。新鲜分离的褐色脂肪细胞对NE的反应是氧摄取率增加10至20倍。这种对NE产生产热反应的能力在24小时内得以维持。然而，当褐色脂肪细胞与NE一起孵育1至6小时或24小时时，未观察到[35S]蛋氨酸掺入细胞蛋白质的显著增加。当通过SDS-PAGE分离标记的细胞蛋白质并通过放射自显影进行可视化时，未观察到蛋白质标记的选择性变化，特别是在解偶联蛋白（32 kDa）区域。同样，NE的存在对[35S]蛋氨酸掺入可免疫沉淀的解偶联蛋白没有影响。这些结果表明，理查森地松鼠BAT中NE的产热作用和生长作用之间存在分离。
