Astrocytic Ca2+ signaling evoked by sensory stimulation in vivo.
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.
Wang
Xiaohai
X
Center for Aging and Developmental Biology, Department of Neurosurgery, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, USA.
Lou
Nanhong
N
Xu
Qiwu
Q
Tian
Guo-Feng
GF
Peng
Wei Guo
WG
Han
Xiaoning
X
Kang
Jian
J
Takano
Takahiro
T
Nedergaard
Maiken
M
D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005260:Female; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D051379:Mice; D010812:Physical Stimulation; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000378:metabolism; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D013003:Somatosensory Cortex / Q000166:cytology / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014110:Touch / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D014738:Vibrissae / Q000294:innervation / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D002118:Calcium