Long-term potentiation of hippocampal mossy fiber synapses is blocked by postsynaptic injection of calcium chelators.
The role of intracellular calcium in an APV-insensitive form of long-term potentiation (LTP) has been studied at the hippocampal mossy fiber synapse. Intracellular calcium was buffered by iontophoretic injection of either BAPTA or QUIN-2, into CA3 pyramidal neurons. The slow calcium-dependent after hyperpolarization was used as an indicator of buffering. LTP was elicited in control and in APV-treated cells (6/6 and 4/5 cell, respectively). In contrast, LTP was observed in only 2/9 BAPTA-loaded cells and in 1/4 QUIN-2-loaded cells. The magnitude of LTP for control and APV-treated cells were not significantly different, but both groups showed significantly greater LTP than BAPTA-loaded cells. These results suggest that an increase in postsynaptic calcium is required for the induction of mossy fiber LTP.
Williams
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Department of Neurology, Baylor College of Medicine, Houston, Texas 77030.
Johnston
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D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology*; D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D002118:Calcium; D002470:Cell Survival / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology / Q000031:analogs & derivatives; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D007267:Injections; D009412:Nerve Fibers / Q000502:physiology*; D051381:Rats; D013569:Synapses / Q000502:physiology*; D013997:Time Factors
D000634:Aminoquinolines; D002614:Chelating Agents; D004533:Egtazic Acid; D015763:2-Amino-5-phosphonovalerate; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; C035739:Quin2; D002118:Calcium