N-Type calcium channels in the developing rat hippocampus: subunit, complex, and regional expression.
The expression of multiple classes of voltage-dependent calcium channels (VDCCs) allows neurons to tailor calcium signaling to functionally discrete cellular regions. In the developing hippocampus a central issue is whether the expression of VDCC subtypes plays a role in key phases such as migration and synaptogenesis. Using radioligand binding and immunoblotting, we show that some N-type VDCCs exist before birth, consistent with a role in migration; however, most N-VDCC subunit expression is postnatal, coinciding with synaptogenesis. Immunoprecipitation studies indicate that the increased expression of N-VDCCs in early development occurs without subunit switching because there is no change in the fraction of beta3 subunits in the N-VDCC alpha1B-beta3 heteromers. Fluorescence imaging of cell surface N-VDCCs during this period reveals that N-VDCCs are expressed on somata before dendrites and that this expression is asynchronous between different subfields of the hippocampus (CA3-CA4 before CA1-CA2 and dentate gyrus). Our data argue that N-VDCC expression is an important cue in the genesis of synaptic transmission in discrete hippocampal subfields.
Jones
O T
OT
Playfair Neuroscience Unit, Toronto Hospital Research Institute, Toronto Hospital Western Division, Toronto, Ontario, Canada M5T 2S8.
Bernstein
G M
GM
Jones
E J
EJ
Jugloff
D G
DG
Law
M
M
Wong
W
W
Mills
L R
LR
D000818:Animals; D000906:Antibodies / Q000737:chemistry; D000918:Antibody Specificity; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000032:analysis* / Q000276:immunology; D002540:Cerebral Cortex / Q000737:chemistry / Q000196:embryology / Q000254:growth & development; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D006624:Hippocampus / Q000737:chemistry / Q000196:embryology / Q000254:growth & development; D015151:Immunoblotting; D015640:Ion Channel Gating / Q000502:physiology; D010455:Peptides / Q000494:pharmacology; D011233:Precipitin Tests; D011247:Pregnancy; D017966:Pyramidal Cells / Q000737:chemistry / Q000187:drug effects; D011817:Rabbits; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D020866:omega-Conotoxin GVIA
D000906:Antibodies; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010455:Peptides; D020866:omega-Conotoxin GVIA