Nitric oxide and long-term synaptic depression in the rat hippocampus.
Stimulation of the Schaffer collateral projection to the CA1 region in rat hippocampal slices at 1 Hz for 15 min produced a N-methyl-D-aspartate (NMDA) receptor-dependent long-term depression (LTD) of synaptic responses and, when given after tetanic stimulation, reversed long-term potentiation (LTP). Both LTD and the reversal of LTP were blocked by the nitric oxide (NO) inhibitor L-NG-monomethylargine (L-NMMA). L-NG-nitroarginine (L-NOArg) and hemoglobin also blocked LTD. The inhibition of LTD by L-NMMA was overcome by L- but not D-arginine. Sodium nitroprusside and S-nitrosocysteine, agents that spontaneously release NO, mimicked the effect of 1 Hz stimulation. These results indicate that NO mediates LTD produced by sustained 1 Hz activation of CA1 synapses and support the hypothesis that NO mediates the inhibition of LTP produced by untimely activation of NMDA receptors.
Izumi
Y
Y
Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110.
Zorumski
C F
CF
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002248:Carbon Monoxide / Q000378:metabolism; D004558:Electric Stimulation; D006454:Hemoglobins / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D019335:Nitroarginine; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology; D013569:Synapses / Q000187:drug effects*; D019323:omega-N-Methylarginine
D006454:Hemoglobins; D016194:Receptors, N-Methyl-D-Aspartate; D009599:Nitroprusside; D019335:Nitroarginine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D002248:Carbon Monoxide; D001120:Arginine