Nitric oxide synthase inhibitors block long-term potentiation induced by weak but not strong tetanic stimulation at physiological brain temperatures in rat hippocampal slices.
Nitric oxide synthase (NOS) inhibitors have been shown to block long-term synaptic enhancements in the mammalian hippocampus. This effect has been somewhat controversial, however, showing sensitivity to both temperature and stimulus strength. We have demonstrated a differential effect of the NOS inhibitor L-NG-nitroarginine (NOArg) on long-term potentiation (LTP) induced by weak and strong tetanic stimulation in slices of rat hippocampus. NOArg prevented LTP induction by a weak tetanus that produced stable potentiation in control slices, while the NOS inhibitor was without effect when strong tetani were used. These results suggest that nitric oxide (NO) produced as a result of tetanic stimulation plays a role in adjusting the threshold of LTP induction, but is not necessary for establishing synaptic enhancement under conditions of strong synaptic activation.
Haley
J E
JE
Department of Psychology, University of Minnesota, Minneapolis 55455.
Malen
P L
PL
Chapman
P F
PF
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors*; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects*; D008297:Male; D019001:Nitric Oxide Synthase; D019335:Nitroarginine; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects; D013696:Temperature
D016194:Receptors, N-Methyl-D-Aspartate; D019335:Nitroarginine; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases