Glutamate-induced increases in intracellular Ca2+ in cultured rat neocortical neurons.
In neurons, changes in intracellular Ca2+ concentration ([Ca2+]i) trigger neurotransmitter release, regulate membrane excitability, affect gene expression, and govern short- and long-term forms of synaptic plasticity. Rises in cytoplasmic Ca2+ are thought to underlie the various effects of glutamatergic neurotransmitters within the central nervous system. In the present study, we applied a calcium imaging technique using a confocal laser scanning microscope to investigate the effects of excitatory amino acids on glutamate induced calcium influx in primary cultured neocortical neurons. Glutamate (5 microM) induced increases in [Ca2+]i in both the soma and dendritic processes of the cells. The increase was partially blocked by 10 microM DL-2-amino-5-phosphovaleric acid (APV), a NMDA antagonist. The reduction was higher in the dendritic process than in the cell body: the reduction was 58% in the cell body and 67% in the dendritic processes. In contrast, 5 microM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a non-NMDA antagonist, had less effect on the response. We observed an 11% reduction in the dendritic processes, but no change in the cell bodies. The results demonstrated the heterogeneous distribution of APV- and CNQX-sensitive channels in primary cultured neocortical neurons. In both the cell body and dendritic processes, [Ca2+]i increase induced by low concentrations of glutamate was mainly due to the activation of NMDA receptors.
Wang
Gang
G
Department of Bioengineering, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 8900065, Japan.
Ding
Shan
S
Yunokuchi
Kazutomo
K
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002451:Cell Compartmentation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005333:Fetus; D005456:Fluorescent Dyes; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism*; D019579:Neocortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D015220:Calcium Channels; D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D005456:Fluorescent Dyes; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D002118:Calcium