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An elevated plus-maze consisting of two open and two enclosed arms was employed for an evaluation of memory in mice. Mice in the plus-maze escaped from the open arm to the enclosed arm because mice apparently dislike open and high spaces. The time it took for the mice to move from the open arm to the enclosed arm (transfer latency) was recorded. The(More)
The potentiating effect of low doses of sigma ligands on the N-methyl-D-aspartate (NMDA)-induced excitation of pyramidal CA3 dorsal hippocampal neurons has recently been reported. In the present study, we investigated behavioral effects relevant to these findings in the experimental amnesia induced by the non-competitive NMDA antagonist, dizocilpine(More)
Learning and memory were previously evaluated by using the elevated plus-maze test in mice. We investigated whether this method could be used for the evaluation of amnesic properties of drugs, including those which alter behavior on the first (training) trial. Six drugs of different types, scopolamine, MK-801(More)
The effect of intracerebroventricular (i.c.v.) injection of dynorphin A-(1-13) on the memory process was examined in mice, using spontaneous alternation performance related to working memory in a Y-maze. Dynorphin A-(1-13) (1, 3 and 10 micrograms) influenced neither spontaneous alternation performance nor total arm entries, which are considered to reflect(More)
The effects of intracerebroventricular administration of dynorphin A(1-13) on scopolamine- and pirenzepine-induced amnesia were investigated in mice by observing the step-down-type passive avoidance response and spontaneous alternation performance. The pre- or post-training, or preretention administration of dynorphin A(1-13) (0.3-10 micrograms) alone(More)
The effects of i.c.v. injection of the mu-selective opioid receptor agonist DAMGO and the effects of its combination with the endogenous kappa-opioid receptor agonist dynorphin A-(1-13) on memory processes were examined in mice, using spontaneous alternation performance associated with working memory in a Y-maze. DAMGO (10 and/or 30 ng) impaired spontaneous(More)
The effects of N-(2,6-dimethyl-phenyl)-2-(2-oxo-1-pyrrolidinyl)acetamide (DM-9384), a cyclic derivative of GABA, were investigated and compared with those of aniracetam in an animal model of amnesia, using a passive avoidance task with animals that have GABAergic neuronal dysfunctions. Pre- and post-training administration of DM-9384 and aniracetam(More)
The effect of dynorphin A-(1-13), an endogenous kappa-opioid receptor agonist, on memory dysfunctions induced by transient cerebral ischemia in mice was investigated by using three different tasks, namely, spontaneous alternation, elevated plus-maze performance, and passive avoidance behavior. Transient ischemia produced a marked memory dysfunction in mice,(More)
MK-801 (30–100 µg/kg, SC) impaired spontaneous alternation behavior of mice, a behavior related to the spatial working memory. 1,3-Di-(2-tolyl)guanidine (DTG),(+)-pentazocine and (+)-SKF 10,047 (100 µg/kg, SC), putative σ agonists, administered 10 min before MK-801, partially but significantly reversed the impairment, without affecting the concomitant(More)
Transient ischemia produced marked memory dysfunctions in mice on three different tasks, spontaneous alternation, elevated plus-maze and passive avoidance, as tested 1, 1-2, and 2-3 days after ischemic insult, respectively. U-50,488H, a kappa-opioid receptor agonist, administered 20 min before ischemic insult markedly prevented the impairment of spontaneous(More)