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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 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)
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)
During anesthesia in mice, both common carotid arteries were tied loosely with an overhand knot suture (an occluder), while two snares (releasers) were placed in the knot so that it could be repeatedly tightened to occlude the arteries and loosened again to allow for reperfusion while the mice were conscious and unrestrained. The incidence of mortality as(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 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)
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)
The present study was designed to clarify whether dopamine systems are involved in the effect of dynorphin A-(1-13), an endogenous kappa-opioid receptor agonist, on the scopolamine-induced impairment of spontaneous alternation performance related to working memory in mice. Sulpiride (10 and/or 30 mg/kg), a dopamine D2-selective antagonist, markedly improved(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)
Mild hypothermia protects against neuronal damage after transient global ischemia in experimental animals. The exact mechanism of this protective effect remains to be elucidated. The purpose of the present study was to investigate the molecular mechanisms relevant to different neurologic responses to hypothermia and normothermia. Transient global ischemia(More)