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Synapse-to-synapse variation of calcium channel subtype contributions in large mossy fiber terminals of mouse hippocampus
- Source :
- Neuroscience. 136:1003-1014
- Publication Year :
- 2005
- Publisher :
- Elsevier BV, 2005.
-
Abstract
- Both N- and P/Q-type voltage-dependent calcium channels are involved in fast transmitter release in the hippocampus, but are differentially regulated. Although variable contributions of voltage-dependent calcium channel subtypes to presynaptic Ca 2+ influx have been suggested to give a neural network of great diversity, their presence has only been demonstrated in a culture system and has remained unclear in the brain. Here, the individual large mossy fiber presynaptic terminal was labeled with Ca 2+ /Sr 2+ -sensitive fluorescent dextrans in the hippocampal slice of the mouse. The fractional contribution of voltage-dependent calcium channel subtypes to presynaptic Ca 2+ /Sr 2+ influx was directly measured by the sensitivity of Ca 2+ /Sr 2+ -dependent fluorescent increment to subtype-selective neurotoxins, ω-conotoxin GVIA (an N-type selective blocker), ω-agatoxin IVA (a P/Q-type selective blocker) and SNX-482 (an R-type selective blocker). Synapse-to-synapse comparison of large mossy fiber terminals revealed that the contributions of N- and R-type voltage-dependent calcium channels varied more widely than that of P/Q-type. Even two large mossy fiber presynaptic terminals neighboring on the same axon differed in the fractional contributions of N- and R-type voltage-dependent calcium channels. On the other hand, these terminals were similar in the fractional contributions of P/Q-type voltage-dependent calcium channels. These results provide direct evidence that individual large mossy fiber synapses are differential in the contribution of N- and R-type voltage-dependent calcium channel subtypes to presynaptic Ca 2+ /Sr 2+ influx. We suggest that the synapse-to-synapse variation of presynaptic voltage-dependent calcium channel subtype contributions may be one of the mechanisms amplifying diversity of the hippocampal network.
- Subjects :
- Male
Mossy fiber (hippocampus)
Time Factors
P-type calcium channel
Presynaptic Terminals
chemistry.chemical_element
In Vitro Techniques
Calcium
Hippocampus
Mice
Calcium imaging
Animals
Calcium Signaling
Probability
Neurons
Voltage-dependent calcium channel
Chemistry
General Neuroscience
Calcium channel
T-type calcium channel
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
Calcium Channel Blockers
Electric Stimulation
R-type calcium channel
Calcium Channel Agonists
Protein Subunits
Animals, Newborn
Strontium
Mossy Fibers, Hippocampal
Synapses
Biophysics
Female
Calcium Channels
Neuroscience
Cadmium
Subjects
Details
- ISSN :
- 03064522
- Volume :
- 136
- Database :
- OpenAIRE
- Journal :
- Neuroscience
- Accession number :
- edsair.doi.dedup.....cd99f9a458ab13d82c5e198137a4199b