Department of Chemistry and Biochemistry, University of Alaska Fairbanks, 900 Yukon Drive Rm. 194, Fairbanks, AK 99775-6160, USA; Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, 2140 Koyukuk Drive, Fairbanks, AK 99775-7000 USA.
Department of Chemistry and Biochemistry, University of Alaska Fairbanks, 900 Yukon Drive Rm. 194, Fairbanks, AK 99775-6160, USA; Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, 2140 Koyukuk Drive, Fairbanks, AK 99775-7000 USA.
J Chem Neuroanat. 2021 Apr;113:101920. doi: 10.1016/j.jchemneu.2021.101920. Epub 2021 Jan 27.
Hibernation is a seasonal strategy to conserve energy, characterized by modified thermoregulation, an increase in sleep pressure and drastic metabolic changes. Glial cells such as astrocytes and tanycytes are the brain metabolic sensors, but it remains unknown whether they contribute to seasonal expression of hibernation. The onset of hibernation is controlled by an undefined endogenous circannual rhythm in which adenosine plays a role through the activation of the A adenosine receptor (AAR). Seasonal changes in brain levels of adenosine may contribute to an increase in AAR sensitivity leading to the onset of hibernation. The primary regulator of extracellular adenosine concentration is adenosine kinase, which is located in astrocytes. Using immunohistochemistry to localize and quantify adenosine kinase in Arctic ground squirrels' brain collected during different seasons, we report lower expression of adenosine kinase in the third ventricle tanycytes in winter compared to summer; a similar change was not seen in astrocytes. Moreover, for the first time, we describe adenosine kinase expression in tanycyte cell bodies in the hypothalamus and in the area postrema, both brain regions involved in energy homeostasis. Next we describe seasonal changes in tanycyte morphology in the hypothalamus. Although still speculative, our findings contribute to a model whereby adenosine kinase in tanycytes regulates seasonal changes in extracellular concentration of adenosine underling the seasonal expression of hibernation.
冬眠是一种节能的季节性策略，其特征为体温调节改变、睡眠压力增加和代谢剧烈变化。神经胶质细胞（如星形胶质细胞和室管膜细胞）是大脑代谢传感器，但它们是否有助于冬眠的季节性表达仍不清楚。冬眠的开始受未定义的内源性年节律控制，其中腺苷通过激活 A 腺苷受体（AAR）发挥作用。大脑中腺苷水平的季节性变化可能导致 AAR 敏感性增加，从而引发冬眠。细胞外腺苷浓度的主要调节剂是位于星形胶质细胞中的腺苷激酶。通过免疫组织化学方法定位和定量不同季节收集的北极地松鼠大脑中的腺苷激酶，我们报告在冬季第三脑室室管膜细胞中的腺苷激酶表达低于夏季；星形胶质细胞中没有观察到类似的变化。此外，我们首次描述了在下丘脑和后区的室管膜细胞体中存在腺苷激酶表达，这两个脑区都与能量平衡有关。接下来，我们描述了下丘脑内室管膜细胞形态的季节性变化。尽管仍有推测，但我们的发现有助于建立一个模型，即室管膜细胞中的腺苷激酶调节冬眠季节性表达下细胞外腺苷浓度的季节性变化。
