Department of Neurophysiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria.
Department of Physiology, David Geffen Schoof of Medicine, University of California Los Angeles, Los Angeles, California, USA.
Glia. 2021 Jul;69(7):1749-1766. doi: 10.1002/glia.23990. Epub 2021 Mar 10.
Astrocytes are indispensable for proper neuronal functioning. Given the diverse needs of neuronal circuits and the variety of tasks astrocytes perform, the perceived homogeneous nature of astrocytes has been questioned. In the spinal dorsal horn, complex neuronal circuitries regulate the integration of sensory information of different modalities. The dorsal horn is organized in a distinct laminar manner based on termination patterns of high- and low-threshold afferent fibers and neuronal properties. Neurons in laminae I (L1) and II (L2) integrate potentially painful, nociceptive information, whereas neurons in lamina III (L3) and deeper laminae integrate innocuous, tactile information from the periphery. Sensory information is also integrated by an uncharacterized network of astrocytes. How these lamina-specific characteristics of neuronal circuits of the dorsal horn are of functional importance for properties of astrocytes is currently unknown. We addressed if astrocytes in L1, L2, and L3 of the upper dorsal horn of mice are differentially equipped for the needs of neuronal circuits that process sensory information of different modalities. We found that astrocytes in L1 and L2 were characterized by a higher density, higher expression of GFAP, Cx43, and GLAST and a faster coupling speed than astrocytes located in L3. L1 astrocytes were more responsive to Kir4.1 blockade and had higher levels of AQP4 compared to L3 astrocytes. In contrast, basic membrane properties, network formation, and somatic intracellular calcium signaling were similar in L1-L3 astrocytes. Our data indicate that the properties of spinal astrocytes are fine-tuned for the integration of nociceptive versus tactile information.
星形胶质细胞对于神经元的正常功能是不可或缺的。鉴于神经元回路的多样化需求以及星形胶质细胞所执行的各种任务，星形胶质细胞被认为是同质的这一观点受到了质疑。在脊髓背角，复杂的神经元回路调节着不同感觉模态的信息整合。根据高阈值和低阈值传入纤维以及神经元特性的终止模式，背角以明显的层状方式组织。位于 I 层（L1）和 II 层（L2）的神经元整合潜在的疼痛性伤害感受信息，而位于 III 层（L3）和更深层的神经元整合来自外周的无害触觉信息。感觉信息也由星形胶质细胞的未被表征的网络进行整合。目前尚不清楚背角神经元回路的这些层特异性特征对于星形胶质细胞功能的重要性。我们研究了是否位于小鼠上背角 L1、L2 和 L3 的星形胶质细胞在装备上存在差异，以满足处理不同感觉模态信息的神经元回路的需求。我们发现 L1 和 L2 中的星形胶质细胞的密度更高，GFAP、Cx43 和 GLAST 的表达更高，偶联速度更快，而位于 L3 的星形胶质细胞则相反。L1 星形胶质细胞对 Kir4.1 阻断的反应性更强，AQP4 水平也高于 L3 星形胶质细胞。相比之下，L1-L3 星形胶质细胞的基本膜特性、网络形成和体细胞内钙信号传导相似。我们的数据表明，脊髓星形胶质细胞的特性经过精细调整，以适应伤害感受信息与触觉信息的整合。
