Inhibition of dorsal hippocampal nitric oxide synthesis potentiates ethanol-induced state-dependent memory in mice.
In an effort to understand the involvement of dorsal hippocampal nitric oxide system in ethanol (ETOH)-induced state-dependent memory, the effects of microinjection of l-arginine (a precursor of nitric oxide) and/or l-NAME (a nitric oxide synthase inhibitor) into the CA1 regions of dorsal hippocampus on this kind of memory were examined. In order to assess memory retrieval, a single trial step-down inhibitory avoidance task was used in mice. Pre-training intraperitoneal administration of ETOH (0.5 and 1g/kg) dose dependently caused amnesia, while pre-test administration of the same doses of ETOH restored the retrieval and induced state-dependent memory. Pre-test microinjection of l-arginine (0.5, 0.75 and 1 microg/mouse), into the CA1 region of dorsal hippocampus (intra-CA1) had no effect on memory retrieval. However, pre-test intra-CA1 microinjection of the same doses of l-arginine interestingly inhibited ETOH-induced state-dependent memory. The maximum response was obtained with 1 microg/mouse of l-arginine. Furthermore, memory impairment was produced following pre-test intra-CA1 microinjection of l-NAME (0.5, 0.75 and 1 microg/mouse). Pre-test co-administration of a higher dose of l-NAME (1 microg/mouse, intra-CA1) with an ineffective dose of ETOH (0.25 g/kg), improved the memory retrieval. Pre-test intra-CA1 microinjection of l-arginine or l-NAME could not affect ETOH-induced amnesia. In addition, l-arginine-induced inhibition of the pre-test ETOH response was decreased by pre-test microinjection of l-NAME. The ensemble of these observations suggests that ETOH-induced state-dependent memory can be modulated through the dorsal hippocampal nitric oxide system.
Rezayof
Ameneh
A
Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran. rezayof@khayam.ut.ac.ir
Zare-Chahoki
Ameneh
A
Zarrindast
Mohammad-Reza
MR
Rassouli
Yassaman
Y
D000704:Analysis of Variance; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D011930:Reaction Time / Q000187:drug effects
D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D000431:Ethanol; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester