Influence of nitric oxide agents in the dorsal hippocampus of mice on anxiogenic-like effect induced by histamine.
Histaminergic receptors and neuronal nitric oxide synthase (nNOS) are co-expressed at high levels in the hippocampal neurons and alter anxiety-like behaviors in rodents. Since the dorsal hippocampus may be involved in modulation of anxiety-like behaviors, the aim of the present study was to assess whether the nitric oxide (NO) system in the dorsal hippocampus affects anxiety-like behaviors induced by histaminergic agents in mice. The effects of the NO precursor, L-arginine and NOS inhibitor, L-nitro-amino-methyl-ester (L-NAME) on histamine, pyrilamine and ranitidine responses in elevated plus maze (E.P.M.) in mice were investigated. Intra-CA1 microinjection of histamine (9 μg/mouse) or H1 receptor antagonist, pyrilamine (3, 6 and 9 μg/mouse), but not H2 receptor antagonist, ranitidine decreased the percentage of open arm time (%OAT) and open arm entries (%OAE), without affecting locomotor activity, suggesting an anxiogenic-like response. Both L-arginine (0.4 and 0.8 μg/mouse) and L-NAME (40 ng/mouse) when injected into the dorsal hippocampus induced anxiety-like behaviors, but the drugs reversed the anxiogenic response induced by the effective dose of histamine (9 μg/mouse) or pyrilamine (9 μg/mouse). Our results also indicated that intra-CA1 administration of L-arginine and L-NAME, in the presence or absence of ranitidine, exerted an anxiogenic effect. The results may indicate a modulatory role for NO in the dorsal hippocampus in the anxiogenic-like response induced by histamine or pyrilamine.
Department of Biology, Faculty of Basic Sciences, Islamic Azad University, Ardabil Branch, Ardabil, Iran.
Morteza
M
Piri
Mohammad
M
Nasehi
Malihe
M
Asgariyan
Mohammad Reza
MR
Zarrindast
D000818:Animals; D001007:Anxiety / Q000139:chemically induced* / Q000517:prevention & control* / Q000523:psychology; D001120:Arginine / Q000494:pharmacology; D056547:CA1 Region, Hippocampal / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects*; D006632:Histamine; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000494:pharmacology; D008297:Male; D051379:Mice; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D052248:Nitric Oxide Synthase Type I / Q000037:antagonists & inhibitors; D011738:Pyrilamine / Q000494:pharmacology; D011899:Ranitidine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D009569:Nitric Oxide; D006632:Histamine; D011899:Ranitidine; D001120:Arginine; D052248:Nitric Oxide Synthase Type I; D011738:Pyrilamine; D019331:NG-Nitroarginine Methyl Ester