Pronounced heterothermic responses are relatively rare among birds. Along with taxa such as hummingbirds and caprimulgids, the order Coliiformes (mousebirds) is known to possess the physiological capacity for torpor. During torpor, body temperature is greatly reduced and a bird becomes unresponsive to external stimuli until ambient temperatures return to more favorable conditions. Under such conditions, these birds are forced to rely only on their internal fuel storage for energy and show great reduction in metabolic rates by decreasing energy-expensive processes. This study investigated the role of the key insulin-Akt signaling kinase pathway involved in regulating energy metabolism and protein translation in the liver, kidney, heart, skeletal muscle, and brain of the speckled mousebird (Colius striatus). The degree of phosphorylation of well-conserved target residues with important regulatory function was examined in both the euthermic control and torpid birds. The results demonstrated marked differences in responses between the tissues with decreases in RPS6 S235/236 phosphorylation in the kidney (0.52 fold of euthermic) and muscle (0.29 fold of euthermic) as well as decreases in GS3K3β S9 in muscle (0.60 fold of euthermic) and GSK3α S21 (0.71 fold of euthermic) phosphorylation in kidney during torpor, suggesting a downregulation of this pathway. Interestingly, the liver demonstrated an increase in RPS6 S235/236 (2.89 fold increase) and P70S6K T412 (1.44 fold increase) phosphorylation in the torpor group suggesting that protein translation is maintained in this tissue. This study demonstrates that avian torpor is a complex phenomenon and alterations in this signaling pathway follow a tissue specific pattern.

明显的异温反应在鸟类中相对罕见。与蜂鸟和山羊科动物等分类群一样，大肠菌目（鼠鸟）已知具有麻木的生理能力。在麻木期间，体温大大降低，鸟类对外部刺激没有反应，直到环境温度恢复到更有利的条件。在这种情况下，这些鸟类被迫仅依靠其内部燃料储存来获取能量，并通过减少耗能过程来显着降低代谢率。本研究调查了关键的胰岛素-Akt 信号激酶通路在调节斑点鼠鸟（Colius striatus）肝脏、肾脏、心脏、骨骼肌和大脑中的能量代谢和蛋白质翻译中的作用。）。在恒温控制和麻木鸟类中检查了具有重要调节功能的保存完好的目标残基的磷酸化程度。结果表明，组织之间的反应存在显着差异，肾脏（真热的 0.52 倍）和肌肉（真热的 0.29 倍）中 RPS6 S235/236 磷酸化的降低以及肌肉中 GS3K3β S9 的降低（真热的 0.60 倍）和 GSK3α S21（正常体温的 0.71 倍）磷酸化在麻木期间肾脏中，表明该途径的下调。有趣的是，肝脏表现出在麻木组中 RPS6 S235/236（增加 2.89 倍）和 P70S6K T412（增加 1.44 倍）磷酸化的增加，表明该组织中维持了蛋白质翻译。