Department of Pharmacology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan; Department of Anesthesiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan.
Department of Neurology, Tohoku University School of Medicine, 1-1 Seiryo-cho, Aoba-ku, Sendai, Miyagi 980-8574, Japan.
Biochem Biophys Res Commun. 2014 Sep 5;451(4):562-7. doi: 10.1016/j.bbrc.2014.08.026. Epub 2014 Aug 12.
Aquaporin-4 (AQP4) is a water channel protein that is predominantly expressed in astrocytes in the CNS. The rapid water flux through AQP4 may contribute to electrolyte/water homeostasis and may support neuronal activities in the CNS. On the other hand, little is known about the expression of AQP4 in the peripheral nervous system (PNS). Using AQP4(-/-) mice as a negative control, we demonstrated that AQP4 is also expressed in sensory ganglia, such as trigeminal ganglia and dorsal root ganglia in the PNS. Immunohistochemistry revealed that AQP4 is exclusively localized to satellite glial cells (SGCs) surrounding the cell bodies of the primary afferent sensory neurons in the sensory ganglia. Biochemical analyses revealed that the expression levels of AQP4 in sensory ganglia were considerably lower than those in astrocytes in the CNS. Consistently, behavioral analyses did not show any significant difference in terms of mechanical and cold sensitivity between wild type and AQP4(-/-) mice. Overall, although the pathophysiological relevance of AQP4 in somatosensory perception remains unclear, our findings provide new insight into the involvement of water homeostasis in the peripheral sensory system.
水通道蛋白 4（AQP4）是一种主要在中枢神经系统的星形胶质细胞中表达的水通道蛋白。AQP4 的快速水通量可能有助于电解质/水的动态平衡，并可能支持中枢神经系统中的神经元活动。另一方面，AQP4 在周围神经系统（PNS）中的表达知之甚少。我们使用 AQP4(-/-) 小鼠作为阴性对照，证明 AQP4 也在感觉神经节中表达，如三叉神经节和背根神经节。免疫组织化学显示，AQP4 仅定位于感觉神经节中初级传入感觉神经元胞体周围的卫星胶质细胞（SGC）。生化分析表明，感觉神经节中 AQP4 的表达水平明显低于中枢神经系统中星形胶质细胞的表达水平。行为分析也一致表明，野生型和 AQP4(-/-) 小鼠在机械和冷敏感性方面没有明显差异。总体而言，尽管 AQP4 在躯体感觉感知中的病理生理相关性尚不清楚，但我们的研究结果为水动态平衡参与外周感觉系统提供了新的见解。
