Abstract
Compared with NMDA receptor-dependent LTP, much less is known about the mechanism of induction of NMDA receptor-independent LTP; the most extensively studied form of which is mossy fiber LTP in the hippocampus. In the present study we show that Ca2+-induced Ca2+ release from intracellular stores is involved in the induction of mossy fiber LTP. This release also contributes to the kainate receptor-dependent component of the pronounced synaptic facilitation that occurs during high-frequency stimulation. We also present evidence that the trigger for this Ca2+ release is Ca2+ permeation through kainate receptors. However, these novel synaptic mechanisms can be bypassed when the Ca2+ concentration is raised (from 2 to 4 mM), via a compensatory involvement of L-type Ca2+ channels. These findings suggest that presynaptic kainate receptors at mossy fiber synapses can initiate a cascade involving Ca2+ release from intracellular stores that is important in both short-term and long-term plasticity.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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2-Amino-5-phosphonovalerate / pharmacology
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Animals
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Animals, Newborn
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Arthropod Venoms / pharmacology
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Calcium / metabolism*
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Calcium Channel Blockers / pharmacology
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Drug Interactions
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Electric Stimulation
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Enzyme Inhibitors / pharmacology
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Excitatory Amino Acid Agonists / pharmacology
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Excitatory Amino Acid Antagonists / pharmacology
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Excitatory Postsynaptic Potentials / drug effects
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Excitatory Postsynaptic Potentials / physiology
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Extracellular Space
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In Vitro Techniques
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Isoquinolines / pharmacology
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Kainic Acid / pharmacology
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Long-Term Potentiation / drug effects
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Long-Term Potentiation / physiology*
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Magnesium / metabolism
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Membrane Potentials / drug effects
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Membrane Potentials / physiology
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Mossy Fibers, Hippocampal / drug effects
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Mossy Fibers, Hippocampal / physiology*
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Nifedipine / pharmacology
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Patch-Clamp Techniques
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Rats
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Receptors, Kainic Acid / antagonists & inhibitors
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Receptors, Kainic Acid / drug effects
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Receptors, Kainic Acid / metabolism*
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Ryanodine / pharmacology
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Synaptic Transmission / drug effects
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Synaptic Transmission / physiology*
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Thapsigargin / pharmacology
Substances
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Arthropod Venoms
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Calcium Channel Blockers
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Enzyme Inhibitors
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Excitatory Amino Acid Agonists
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Excitatory Amino Acid Antagonists
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Isoquinolines
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LY382884
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Receptors, Kainic Acid
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Ryanodine
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Thapsigargin
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2-Amino-5-phosphonovalerate
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Magnesium
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Nifedipine
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Kainic Acid
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Calcium