Presynaptic calcium current modulation by a metabotropic glutamate receptor.
Metabotropic glutamate receptors (mGluRs) regulate transmitter release at mammalian central synapses. However, because of the difficulty of recording from mammalian presynaptic terminals, the mechanism underlying mGluR-mediated presynaptic inhibition is not known. Here, simultaneous recordings from a giant presynaptic terminal, the calyx of Held, and its postsynaptic target in the medial nucleus of the trapezoid body were obtained in rat brainstem slices. Agonists of mGluRs suppressed a high voltage-activated P/Q-type calcium conductance in the presynaptic terminal, thereby inhibiting transmitter release at this glutamatergic synapse. Because several forms of presynaptic modulation and plasticity are mediated by mGluRs, this identification of a target ion channel is a first step toward elucidation of their molecular mechanism.
Takahashi
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Department of Neurophysiology, Institute for Brain Research, Faculty of Medicine, University of Tokyo, Tokyo 113, Japan. ttakahas-tky@umin.u-tokyo.ac.jp
Forsythe
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Tsujimoto
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Barnes-Davies
M
M
Onodera
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K
D000613:Aminobutyrates / Q000494:pharmacology; D000818:Animals; D001933:Brain Stem; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D066298:In Vitro Techniques; D018377:Neurotransmitter Agents / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*; D009435:Synaptic Transmission
D000613:Aminobutyrates; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D018690:Excitatory Amino Acid Agonists; D018377:Neurotransmitter Agents; D015221:Potassium Channels; D018094:Receptors, Metabotropic Glutamate; D002104:Cadmium; C012729:2-amino-4-phosphonobutyric acid; D011188:Potassium; D002118:Calcium