Nature Neuroscience 9, 816 - 823 (2006)
Published online: 14 May 2006; | doi:10.1038/nn1703
Astrocytic Ca2+ signaling evoked by sensory stimulation in vivoXiaohai Wang1, Nanhong Lou1, Qiwu Xu1, Guo-Feng Tian1, Wei Guo Peng1, Xiaoning Han1, Jian Kang2, Takahiro Takano1
& Maiken Nedergaard11
Center for Aging and Developmental Biology, Department of Neurosurgery, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, USA. 2
Department of Cell Biology and Anatomy, New York Medical College, 30 Sunshine Cottage Road, Valhalla, New York 10595, USA.
Correspondence should be addressed to Maiken Nedergaard Nedergaard@URMC.Rochester.edu 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 (Ca2+) within the barrel cortex of adult mice. Increases in astrocytic Ca2+ 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 Ca2+ 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 Ca2+ occur independently of postsynaptic excitatory activity.
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