Evidence for glutamate-mediated activation of hippocampal neurons by glial calcium waves.
Communication from astrocytes to neurons has recently been reported by two laboratories, but different mechanisms were though to underlie glial calcium wave activation of associated neurons. Neuronal calcium elevation by glia observed in the present report is similar to that reported previously, where an increase in neuronal calcium was demonstrated in response to glial stimulation. In the present study hippocampal neurons plated on a confluent glial monolayer displayed a transient increase in intracellular calcium following a short delay after the passage of a wave of increased calcium in underlying glia. Activated cells displayed action potentials in response to glial waves and showed antineurofilament immunoreactivity. Finally, the N-methyl-D-aspartate glutamate receptor antagonist DL-2-amino-5-phosphonovaleric acid and the non-NMDA glutamate receptor antagonist 6,7-dinitroquinoxaline-2,3-dione significantly reduced the responsiveness of neurons to glial calcium waves. Our results indicate that hippocampal neurons growing on hippocampal or cortical astrocytes respond to glial calcium waves with elevations in calcium and increased electrical activity. Furthermore, we show that in most cases this communication appears to be mediated by ionotropic glutamate receptor channels.
Department of Anatomy and Neurobiology, Colorado State University, Ft. Collins 80523, USA.
T D
TD
Hassinger
P B
PB
Atkinson
G J
GJ
Strecker
L R
LR
Whalen
F E
FE
Dudek
A H
AH
Kossel
S B
SB
Kater
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002450:Cell Communication; D002478:Cells, Cultured; D004594:Electrophysiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D009457:Neuroglia / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017470:Receptors, Glutamate / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology
D018691:Excitatory Amino Acid Antagonists; D017470:Receptors, Glutamate; D018094:Receptors, Metabotropic Glutamate; D018698:Glutamic Acid; D013779:Tetrodotoxin; D002118:Calcium