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Distribution of high‐voltage‐activated calcium channels in cultured γ‐aminobutyric acidergic neurons from mouse cerebral cortex
Author(s) -
Timmermann Daniel B.,
Westenbroek Ruth E.,
Schousboe Arne,
Catterall William A.
Publication year - 2001
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.10074
Subject(s) - voltage dependent calcium channel , gabaergic , gene isoform , axon , neuroscience , neurotransmitter , calcium channel , chemistry , microbiology and biotechnology , protein subunit , calbindin , calcium , biology , biochemistry , central nervous system , inhibitory postsynaptic potential , organic chemistry , gene
The localization of voltage‐gated calcium channel (VGCC) α 1 subunits in cultured GABAergic mouse cortical neurons was examined by immunocytochemical methods. Ca v 1.2 and Ca v 1.3 subunits of L‐type VGCCs were found in cell bodies and dendrites of GABA‐immunopositive neurons. Likewise, the Ca v 2.3 subunit of R‐type VGCCs was expressed in a somatodendritic pattern. Ca v 2.2 subunits of N‐type channels were found exclusively in small varicosities that were identified as presynaptic nerve terminals based on their expression of synaptic marker proteins. Two splice variants of the Ca v 2.1 subunit of P/Q‐type VGCCs showed widely differing expression patterns. The rbA isoform displayed a purely somatodendritic staining pattern, whereas the BI isoform was confined to axon‐like fibers and nerve terminals. The nerve terminals of these cultured GABAergic neurons express Ca v 2.2 either alone or in combination with Ca v 2.1 (BI isoform) but never express Ca v 2.1 alone. The functional association between VGCCs and the neurotransmitter release machinery was probed using the FM1‐43 dye‐labeling technique. N‐type VGCCs were found to be tightly coupled to exocytosis in these cultured cortical neurons, and P‐type VGCCs were also important in a fraction of the cells. The predominant role of N‐type VGCCs in neurotransmitter release and the specific localization of the BI isoform of Ca v 2.1 in the nerve terminals of these neurons distinguish them from previously studied central neurons. The complementary localization patterns observed for two different isoforms of the Ca v 2.1 subunits provide direct evidence for alternative splicing as a means of generating functional diversity among neuronal calcium channels. © 2002 Wiley‐Liss, Inc.