Department of Pharmacology, School of Medicine, Keio University, Shinanomachi, Shinjuku, 160-8582, Japan; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Kawaguchi, Saitama, 332-0012, Japan; Graduate School of Environment and Information Sciences, Yokohama National University, Japan.
Department of Pharmacology, School of Medicine, Keio University, Shinanomachi, Shinjuku, 160-8582, Japan; College of Engineering, Yokohama National University, Kanagawa, 240-8501, Japan.
Biochem Biophys Res Commun. 2018 Oct 12;504(4):690-697. doi: 10.1016/j.bbrc.2018.09.021. Epub 2018 Sep 11.
Norepinephrine (NE) modulates brain functions depending on both the internal and external environment. While the neuromodulatory actions of NE have been well characterized, the response and involvement of cortical astrocytes to physiological noradrenergic systems remain largely unknown, especially at the molecular level. In this study, we biochemically characterize the action of NE on astrocytes of the murine neocortex. NE stimulation of acute brain slices rapidly increase phosphorylation of connexin 43 (Cx43) at Serine (Ser) 368, in slices from both juvenile and adolescent animals. The phosphorylation is mediated by the protein kinase C (PKC) pathway under the α1-adrenergic receptor and remains elevated for tens of minutes following brief exposure to NE, well after the intracellular calcium level returns to normal level, suggesting the plastic nature of this phosphorylation event. Importantly, this phosphorylation event persists in the absence of neuronal transmissions, suggesting that the effect of NE on Cx43 phosphorylation is induced directly on astrocytes. Furthermore, these NE-induced phosphorylations are associated with biochemical dissociation of Cx43 from gap-junctional plaques to non-junctional compartments. Finally, we show that pharmacological manipulation of the noradrenergic system using psychoactive drugs modulates phosphorylation of Cx43 in the cerebral cortex in vivo. These data suggest that NE acts directly on astrocytes in parallel with neurons and modulates functionally critical connexin channel proteins in a plastic manner. Thus, plasticity of astrocytes induced by the "gliomodulatory" actions of NE may play important roles in their physiological as well as pharmacological actions in the brain.
去甲肾上腺素（NE）根据内部和外部环境调节大脑功能。虽然 NE 的神经调节作用已经得到很好的描述，但皮质星形胶质细胞对生理去甲肾上腺素系统的反应和参与在很大程度上仍然未知，尤其是在分子水平上。在这项研究中，我们从生物化学角度表征了 NE 对小鼠新皮层星形胶质细胞的作用。NE 刺激急性脑片可迅速增加幼年和青少年动物脑片中连接蛋白 43（Cx43）丝氨酸（Ser）368 的磷酸化。这种磷酸化是由蛋白激酶 C（PKC）途径介导的，受α1-肾上腺素能受体调节，在短暂暴露于 NE 后，细胞内钙离子水平恢复正常水平后的数十分钟内仍保持升高，这表明这种磷酸化事件具有可塑性。重要的是，这种磷酸化事件在没有神经元传递的情况下仍然存在，这表明 NE 对 Cx43 磷酸化的影响是直接作用于星形胶质细胞的。此外，这些 NE 诱导的磷酸化与 Cx43 从缝隙连接斑到非连接区的生化解离有关。最后，我们表明使用精神活性药物对去甲肾上腺素能系统的药理学操纵可调节体内大脑皮层中 Cx43 的磷酸化。这些数据表明，NE 与神经元平行作用于星形胶质细胞，并以可塑的方式调节功能关键的连接蛋白通道蛋白。因此，NE 的“神经调节”作用诱导的星形胶质细胞可塑性可能在其生理和药理学作用中发挥重要作用。
