Cold Tolerance in Hypothyroid Rabbits: Role of Skeletal Muscle Mitochondria and Sarcoplasmic Reticulum Ca2+ ATPase Isoform 1 Heat Production
Cold Tolerance in Hypothyroid Rabbits: Role of Skeletal Muscle Mitochondria and Sarcoplasmic Reticulum Ca2+ ATPase Isoform 1 Heat Production
复制标题
DOI：
10.1210/en.2008-0564
复制
发表时间：
2008-12-01
期刊：
影响因子：
4.8
通讯作者：
de Meis, Leopoldo
中科院分区：
文献类型：
--
作者：
Arruda, Ana Paula;Ketzer, Luisa A.;de Meis, Leopoldo
棕色脂肪组织（BAT）参与大鼠和小鼠的体温调节，BAT产生的热量依赖于甲状腺激素和儿茶酚胺的协同作用。对于哺乳动物中的冷诱导产热知之甚少，这些哺乳动物很少或没有BAT，例如兔子。在这些动物中，产热主要发生在骨骼肌中。本工作研究了正常和甲状腺功能低下家兔冷适应（4 ℃，10天）的影响。众所周知，甲状腺功能减退的大鼠在寒冷暴露几小时后死亡。我们现在表明，与大鼠不同，甲状腺功能减退的兔在冷暴露10天后仍能维持体温并存活。与室温下的家兔相比，冷暴露家兔的肌肉显示出氧化肌纤维的暗红色特征。根据这一模式，我们观察到，在正常和甲状腺功能减退的兔子，冷暴露促进骨骼肌线粒体耗氧量的增加。此外，在红色肌肉中，冷适应诱导肌浆网Ca 2 + ATP酶亚型1（SERCA 1）的表达和活性增加，SERCA 1是参与产热的肌肉酶之一。我们的结论是，兔的耐寒性可能与增加肌肉的氧化代谢和热产生SERCA 1，这些变化并不完全依赖于正常的甲状腺功能。（内分泌学149：6262-6271，2008）
Brown adipose tissue ( BAT) is involved in rat and mice thermoregulation, and heat produced by BAT depends on the concerted action of thyroid hormones and catecholamines. Little is known about cold-induced thermogenesis in mammals that have little or no BAT, such as rabbits. In these animals, thermogenesis primarily occurs in skeletal muscle. In this work, we have studied the effect of cold acclimation ( 4 C for 10 d) in normal and hypothyroid rabbits. It is known that hypothyroid rats die after a few hours of cold exposure. We now show that, different from rats, hypothyroid rabbits sustain their body temperature and survive after 10 d cold exposure. When compared with rabbits kept at room temperature, the muscles of cold-exposed rabbits showed a dark red color characteristic of oxidative muscle fibers. According to this pattern, we observed that in both normal and hypothyroid rabbits, cold exposure promotes an increase in oxygen consumption by skeletal muscle mitochondria. Moreover, in red muscle, cold acclimation induces an increase in the expression and activity of sarcoplasmic reticulum Ca2+ ATPase isoform 1 (SERCA1), one of the muscle enzymes involved in heat production. We conclude that rabbit cold tolerance is probably related to increased muscle oxidative metabolism and heat production by SERCA1 and that these changes are not completely dependent on normal thyroid function. ( Endocrinology 149: 6262-6271, 2008)