Further studies concerning the role of nitric oxide in LTP induction and maintenance.
Nitric oxide (NO) has recently been proposed to act as a retrograde messenger to produce long-term potentiation (LTP) in hippocampal area CA1. This notion is based largely on the absence of LTP when hippocampal slices are incubated in the presence of inhibitors of NO synthase (NOS) or of NO scavengers. In the present study, we tested the effects of such compounds on both the induction and maintenance of LTP in field CA1 of hippocampal slices. Incubation of slices in the presence of N-methyl-L-arginine (MLA) or L-nitro-arginine (LNA), two inhibitors of NOS, or in the presence of hemoglobin (Hb), a NO scavenger, produced a large reduction in the magnitude of LTP induced by a theta burst stimulation (TBS) paradigm. These compounds had no effect on the degree of paired-pulse facilitation but produced a significant reduction of the facilitation of postsynaptic responses occurring during TBS. On the other hand, MLA did not prevent the potentiation induced by application of tetraethylammonium (TEA). These results suggest that the inhibition of LTP produced by these agents could be due to an effect on a physiological mechanism that triggers LTP and not necessarily on an event that follows the triggering step.
Musleh
W Y
WY
Neuroscience Program, USC, Los Angeles 90089-2520.
Shahi
K
K
Baudry
M
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D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D016166:Free Radical Scavengers; D006454:Hemoglobins / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase; D019335:Nitroarginine; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000187:drug effects / Q000378:metabolism; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D016166:Free Radical Scavengers; D006454:Hemoglobins; D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D019335:Nitroarginine; D009569:Nitric Oxide; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases