Long-term depression of naïve synapses in adult hippocampus induced by asynchronous synaptic activity.
1. Two independent Schaffer collateral pathways converging to the same pyramidal cell were alternately stimulated by 2-Hz trains (900 pulses) offset by a 150-ms interval in adult rat hippocampal slices. The second input underwent an immediate and persistent long-term depression (LTD). Depression in the first input was smaller than the second input. A narrower interpulse interval (20 ms) failed to induce LTD in either input. 2. Neither the N-methyl-D-aspartate receptor antagonist DL-2-amino-5-phosphonovaleric acid nor the metabotropic glutamate receptor antagonist (+)-alpha-methyl-4-carboxylphenyl-glycine blocked this associative LTD. However, coapplication of these two antagonists blocked LTD. 3. Associative LTD was blocked by prior injection of the Ca2+ chelator bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid into the postsynaptic cell and by bath-applied L-NG-nitroarginine, a nitric oxide synthesis inhibitor. 4. We propose that temporally confined, asynchronous synaptic activity weakens the efficacy of naïve synapses in slices from the adult hippocampus.
Otani
S
S
Roche Institute of Molecular Biology, Nutley, New Jersey 07110, USA.
Connor
J A
JA
D000818:Animals; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D017966:Pyramidal Cells; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D013997:Time Factors
D004533:Egtazic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid