AMPA receptor-mediated modulation of inward rectifier K+ channels in astrocytes of mouse hippocampus.
Astrocytes and neurons are tightly associated and recent data suggest a direct signaling between neuronal and glial cells in vivo. To further analyze these interactions, the patch-clamp technique was combined with single-cell RT-PCR in acute hippocampal brain slices. Subsequent to functional analysis, the cytoplasm of the same cell was harvested to perform transcript analysis and identify subunits that underlie inwardly rectifying K+ currents (I(Kir)) in astrocytes of the CA1 stratum radiatum. Transcripts encoding Kir2.1, Kir2.2, or Kir2.3, were encountered in a majority of cells, while Kir4.1 was less frequent. Further investigation revealed that glial Kir channels are rapidly inhibited upon activation of AMPA-type glutamate receptors, most probably due a receptor-mediated influx of Na+, which plugs the channels from the intracellular side. A transient inhibition of I(Kir) in astrocytes in response to neuronal glutamate release and glial AMPA receptor activation represents a further, so far undetected mechanism to balance neuronal excitability.
Schröder
Wolfgang
W
Experimental Neurobiology, Neurosurgery, University of Bonn, 53105 Bonn, Germany.
Seifert
Gerald
G
Hüttmann
Kerstin
K
Hinterkeuser
Stefan
S
Steinhäuser
Christian
C
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006624:Hippocampus / Q000166:cytology*; D007608:Kainic Acid / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism*; D018091:Receptors, AMPA / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism
D018690:Excitatory Amino Acid Agonists; D024661:Potassium Channels, Inwardly Rectifying; D018091:Receptors, AMPA; D012964:Sodium; D011188:Potassium; D007608:Kainic Acid; D002118:Calcium