POLYAMINE SIGNALING VIA GLIAL CONNEXIN-43 HEMICHANNELS IN RETINA

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 视网膜中的主要神经胶质细胞，M？ller细胞，跨越整个视网膜厚度， 感光细胞到神经节细胞。M？ller细胞接触甚至划分所有神经元 隔室并可以释放神经活性物质以直接调节神经元。一 调节视网膜神经元活性的可能候选物是内源性多胺精胺 （SPM）。多胺精胺和亚精胺（SPM/SPD）主要位于 视网膜中的米勒细胞，但调节许多神经元受体和通道上发现， 视网膜神经元包括AMPA、红藻氨酸、NMDA受体通道和Kir通道。我们 初步数据表明，SPM/SPD从这种神经胶质细胞释放到神经元网络， 神经胶质特异性治疗。我们的工作假设是内源性SPM作为一种信号 视网膜中神经胶质细胞和神经元细胞之间的分子：（i）SPM积累和释放 来自M？ller（神经胶质）细胞，可能通过未贴壁的半间隙连接（半通道） 和（ii）同时作用于几种类型的神经元受体和通道以调节 视网膜神经网络利用电生理学和免疫细胞化学技术， 我们建议通过以下具体目标来检验这一假设： 具体目标1 为了确定米勒神经胶质细胞是否表达必需的生物合成酶， 在生理和病理生理条件下合成多胺。 具体目标2  为了检查SPM通量可能通过连接蛋白半通道或P2 X7 视网膜M？ller（神经胶质）细胞中的受体。 具体目标3  目的：观察精胺对离体海马神经元谷氨酸受体的影响， 视网膜神经元和视网膜整体包埋制备物。 这些研究的结果将提供对精胺依赖性视网膜活动的深入了解， 最终可能导致青光眼、视网膜缺血、谷氨酸盐 兴奋性毒性和随后的神经元死亡。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The major glial cells in the retina, M¿ller cells, span the whole retinal thickness from photoreceptors to ganglion cells. M¿ller cells contact and even delimit all neuronal compartments and can release neuroactive substances to directly regulate neurons. One likely candidate to regulate retinal neuronal activity is the endogenous polyamine spermine (SPM). The polyamines spermine and spermidine (SPM/SPD) are predominantly located in M¿ller cells in the retina, but modulate many neuronal receptors and channels found on retinal neurons including AMPA, kainate, NMDA receptor channels and Kir channels. Our preliminary data demonstrate release of SPM/SPD from this glia to neuronal network under glial specific treatments. Our working hypothesis is that endogenous SPM acts as a signaling molecule between glial and neuronal cells in the retina: (i) SPM is accumulated and released from M¿ller (glial) cells, potentially through unapposed hemi-gap junctions (hemichannels) and (ii) acts simultaneously on several types of neuronal receptors and channels to modulate retinal neuronal networks. Using electrophysiological and immunocytochemical techniques, we propose to test this hypothesis by the following specific aims: Specific aim 1 To determine if M¿ller glial cells express the biosynthetic enzymes necessary for polyamine synthesis under physiological and pathophysiological conditions. Specific aim 2  To examine SPM flux potentially through connexin hemichannels or P2X7 receptors in retinal M¿ller (glial) cells. Specific aim 3  To determine the effect of spermine on glutamate receptors in isolated retinal neurons and in a retinal whole-mount preparation. The results of these studies will provide insight into spermine-dependent retinal activity and may ultimately result in interventions for glaucoma, retinas ischemia, glutamate excitotoxicity and subsequent neuronal death.