Abstract
R-type calcium channels in postsynaptic spines signal through functional calcium microdomains to regulate a calcium/calmodulin-sensitive potassium channel that in turn regulates postsynaptic hippocampal long-term potentiation (LTP). Here, we ask whether R-type calcium channels in presynaptic terminals also signal through calcium microdomains to control presynaptic LTP. We focus on presynaptic LTP at parallel fiber to Purkinje cell synapses in the cerebellum (PF-LTP), which is mediated by calcium/calmodulin-stimulated adenylyl cyclases. Although most presynaptic calcium influx is through N-type and P/Q-type calcium channels, blocking these channels does not disrupt PF-LTP, but blocking R-type calcium channels does. Moreover, global calcium signaling cannot account for the calcium dependence of PF-LTP because R-type channels contribute modestly to overall calcium entry. These findings indicate that, within presynaptic terminals, R-type calcium channels produce calcium microdomains that evoke presynaptic LTP at moderate frequencies that do not greatly increase global calcium levels.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Adenosine A1 Receptor Antagonists / pharmacology
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Analysis of Variance
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Animals
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Animals, Newborn
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Calcium / metabolism*
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Calcium Channel Blockers / pharmacology
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Calcium Channels, R-Type / metabolism*
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Calcium Signaling / drug effects
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Cerebellum / cytology
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Dose-Response Relationship, Drug
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Electric Stimulation / methods
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Excitatory Amino Acid Antagonists / pharmacology
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GABA Antagonists / pharmacology
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In Vitro Techniques
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Long-Term Potentiation / drug effects
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Long-Term Potentiation / physiology*
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Membrane Microdomains / drug effects
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Membrane Microdomains / metabolism*
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Neural Pathways / drug effects
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Neural Pathways / physiology
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Nickel / pharmacology
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Patch-Clamp Techniques / methods
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Phosphinic Acids / pharmacology
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Piperidines / pharmacology
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Presynaptic Terminals / drug effects
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Presynaptic Terminals / physiology*
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Propanolamines / pharmacology
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Purkinje Cells / cytology
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Purkinje Cells / physiology*
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Pyrazoles / pharmacology
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Quinoxalines / pharmacology
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Rats
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Rats, Sprague-Dawley
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Sodium Channel Blockers / pharmacology
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Spider Venoms / pharmacology
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Tetrodotoxin / pharmacology
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Xanthines / pharmacology
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omega-Agatoxin IVA / pharmacology
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omega-Conotoxin GVIA / pharmacology
Substances
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Adenosine A1 Receptor Antagonists
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Calcium Channel Blockers
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Calcium Channels, R-Type
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Excitatory Amino Acid Antagonists
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GABA Antagonists
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Phosphinic Acids
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Piperidines
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Propanolamines
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Pyrazoles
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Quinoxalines
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SNX 482
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Sodium Channel Blockers
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Spider Venoms
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Xanthines
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omega-Agatoxin IVA
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2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline
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CGP 55845A
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AM 251
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Tetrodotoxin
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nickel chloride
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Nickel
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omega-Conotoxin GVIA
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1,3-dipropyl-8-cyclopentylxanthine
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Calcium