title: Deficits in working memory following inhibition of hippocampal nitric oxide synthesis in the rat.
abstract: In order to elucidate the roles of hippocampal nitric oxide (NO) synthesis in working and reference memory performance of rats, the effects of intrahippocampal injections of the NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), on this behavior were examined with a three-panel runway task. In the working memory task, L-NAME, injected bilaterally at 10 and 32 micrograms/side into the dorsal hippocampus, significantly increased the number of errors (attempts to pass through two incorrect panels of the three panel-gates at four choice points). This effect of intrahippocampal L-NAME (32 micrograms/side) on working memory was attenuated by concurrent injection of 100 micrograms/side L-arginine, the precursor of NO. Intrahippocampal injection of the inactive isomer D-NAME at doses up to 32 micrograms/side had no effect on the number of working memory errors. In the reference memory task, neither L-NAME nor D-NAME affected the number of errors when injected into the hippocampus at doses up to 32 micrograms/side. These results suggest that processes mediated by NO synthesis in the hippocampus are involved in working memory, but not in reference memory.
authors.affiliation: Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ohno
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: S
authors.initials: S
authors.lastname: Watanabe
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors*; D000704:Analysis of Variance; D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D003216:Conditioning, Operant; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D008297:Male; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D008845:Microinjections; D019331:NG-Nitroarginine Methyl Ester; D019001:Nitric Oxide Synthase; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D019331:NG-Nitroarginine Methyl Ester