星形胶质细胞和嗅鞘细胞之间的Panglial缝隙连接介导Ca^(2+)瞬变的传递和神经血管耦合

Panglial gap junctions between astrocytes and olfactory ensheathing cells mediate transmission of Ca^(2+) transients and neurovascular coupling

星形胶质细胞排列在有高度组织性的缝隙连接耦合网络中,通过Ca^(2+)波的传播进行通信。星形胶质细胞不仅与邻近的星形胶质细胞结合,而且还与少突胶质细胞偶联,形成panglial合胞体。但panglial合胞体中的神经胶质细胞是否通过Ca^(2+)信号传递信息尚不清楚。我们使用共聚焦Ca^(2+)成像来研究小鼠嗅球中星形胶质细胞和嗅鞘神经胶质细胞(OECs)之间的细胞间通讯。研究结果表明,通过"笼状" ATP和"笼状" tACPD的局部光解可引起的肾小球旁星形胶质细胞中的Ca^(2+)瞬变,导致OEC中随之而来的Ca^(2+)反应。这种从星形胶质细胞到OEC的Ca^(2+)反应的传递在神经元抑制的情况下持续存在,但是当用甘珀酸抑制缝隙连接偶联时消失。当通过DHPG的抽吸在OEC中直接诱发Ca^(2+)瞬变时,它们导致肾小球星形胶质细胞中的Ca^(2+)反应延迟,表明Ca^(2+)信号的panglial传递以双向方式发生。此外,从星形胶质细胞到OEC的Ca^(2+)信号的panglial传递导致嗅觉神经层中OEC相关血管的收缩。本研究结果证明了在缝隙连接耦合的panglial网络中,不同类别的神经胶质细胞之间通过Ca^(2+)进行信号传递,并借此调节嗅球中血管的直径。

Astrocytes are arranged in highly organized gap junction-coupled networks, communicating via the propagation of Ca^2+ waves. Astrocytes are gap junction-coupled not only to neighboring astrocytes, but also to oligodendrocytes, forming so-called panglial syncytia. It is not known, however, whether glial cells in panglial syncytia transmit information using Ca2+ signaling. We used confocal Ca2+ imaging to study intercellular communication between astrocytes and olfactory ensheathing glial cells (OECs) in in-toto preparations of the mouse olfactory bulb. Our results demonstrate that Ca^2+ transients in juxtaglomerular astrocytes, evoked by local photolysis of "caged" ATP and "caged" tACPD, led to subsequent Ca^2+ responses in OECs. This transmission of Ca^2+ responses from astrocytes to OECs persisted in the presence of neuronal inhibition, but was absent when gap junctional coupling was suppressed with carbenoxolone. When Ca^2 + transients were directly evoked in OECs by puff application of DHPG, they resulted in delayed Ca^2 + responses in juxtaglomerular astrocytes, indicating that panglial transmission of Ca^2+ signals occurred in a bidirectional manner. In addition, panglial transmission of Ca^2+ signals from astrocytes to OECs resulted in vasoconstriction of OEC-associated blood vessels in the olfactory nerve layer. Our results demonstrate functional transmission of Ca^2+ signals between different classes of glial cells within gap junction-coupled panglial networks and the resulting regulation of blood vessel diameter in the olfactory bulb.