Wang Xiaohai, Lou Nanhong, Xu Qiwu, Tian Guo-Feng, Peng Wei Guo, Han Xiaoning, Kang Jian, Takano Takahiro, Nedergaard Maiken
Center for Aging and Developmental Biology, Department of Neurosurgery, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, USA.
Nat Neurosci. 2006 Jun;9(6):816-23. doi: 10.1038/nn1703. Epub 2006 May 14.
Although astrocytes are the most abundant cell type in the brain, evidence for their activation during physiological sensory activity is lacking. Here we show that whisker stimulation evokes increases in astrocytic cytosolic calcium (Ca(2+)) within the barrel cortex of adult mice. Increases in astrocytic Ca(2+) were a function of the frequency of stimulation, occurred within several seconds and were inhibited by metabotropic glutamate receptor antagonists. To distinguish between synaptic input and output, local synaptic activity in cortical layer 2 was silenced by iontophoresis of AMPA and NMDA receptor antagonists. The antagonists did not reduce astrocytic Ca(2+) responses despite a marked reduction in excitatory postsynaptic currents in response to whisker stimulation. These findings indicate that astrocytes respond to synaptic input, by means of spillover or ectopic release of glutamate, and that increases in astrocytic Ca(2+) occur independently of postsynaptic excitatory activity.
尽管星形胶质细胞是大脑中数量最多的细胞类型，但缺乏其在生理感觉活动期间被激活的证据。在这里，我们表明，触须刺激会引起成年小鼠桶状皮质内星形胶质细胞胞质钙（Ca(2+)）增加。星形胶质细胞Ca(2+)的增加是刺激频率的函数，在几秒钟内发生，并被代谢型谷氨酸受体拮抗剂抑制。为了区分突触输入和输出，通过AMPA和NMDA受体拮抗剂的离子电渗法使皮质第2层的局部突触活动沉默。尽管对触须刺激的兴奋性突触后电流明显减少，但拮抗剂并未降低星形胶质细胞Ca(2+)反应。这些发现表明，星形胶质细胞通过谷氨酸的溢出或异位释放对突触输入作出反应，并且星形胶质细胞Ca(2+)的增加独立于突触后兴奋性活动而发生。
