神经胶质细胞感知并控制脑内的H^(+)/CO_(2)

Brain H^(+)/CO_(2)sensing and control by glial cells

维持恒定的大脑pH值对于支持神经元的活动、神经元回路内的有效交流以及大脑对信息的有效处理至关重要。本综述重点关注神经胶质细胞如何检测和响应脑组织pH值和CO_(2)浓度的变化,然后触发系统和局部的适应机制,确保脑回路运行环境的稳定。本文详细介绍了神经胶质细胞对H+和CO_(2)敏感的细胞和分子机制,并讨论了神经胶质化学敏感性和信号传导在3个协同工作以保持大脑pH值恒定的关键机制中的作用。本文讨论的证据表明,脑干的星形胶质细胞和边缘神经胶质细胞对中枢呼吸二氧化碳化学感受至关重要——这是机体依据血液和大脑pH值和二氧化碳分压的变化来调节呼吸,以维持系统pH值稳态的一种基本生理机制。本文还回顾了在与神经元活动和代谢变化相关的酸变化负荷条件下,星形胶质细胞参与维持局部脑组织细胞外pH值的证据,并讨论了神经胶质细胞在介导CO_(2)对脑血管影响中的潜在作用。

Maintenance of constant brain pH is critically important to support the activity of individual neurons,ef-fective communication within the neuronal circuits,and,thus,efficient processing of information by the brain.This review article focuses on how glial cells detect and respond to changes in brain tissue pH and concentration of CO_(2),and then trigger systemic and local adaptive mechanisms that ensure a stable milieu for the operation of brain cir-cuits.We give a detailed account of the cellular and molecular mechanisms underlying sensitivity of glial cells to H^(+) and CO_(2)and discuss the role of glial chemosensitivity and signaling in operation of three key mechanisms that work in concert to keep the brain pH constant.We discuss evidence suggesting that astrocytes and marginal glial cells of the brainstem are critically important for central respiratory CO_(2)chemoreception-a fundamental physiological mech-anism that regulates breathing in accord with changes in blood and brain pH and partial pressure of CO_(2)in order to maintain systemic pH homeostasis.We review evidence suggesting that astrocytes are also responsible for the main-tenance of local brain tissue extracellular pH in conditions of variable acid loads associated with changes in the neu-ronal activity and metabolism,and discuss potential role of these glial cells in mediating the effects of CO_(2)on cere-bral vasculature.