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The effects of the dopamine agonists apomorphine, GBR-12909, nomifensine and methamphetamine on latent learning were investigated using a one-trial, water-finding task in mice. Mice without water deprivation were given these agonists or their vehicle before a training trial which consisted of exposure to a novel open-field environment containing a water(More)
The main purpose of the present study was to examine the effect of dopamine blockers on memory processes by means of a one-trial passive avoidance (PA) task with ddY mice. Haloperidol (0.025-0.4 mg/kg i.p.) did not affect the PA response when it was given before the training or retention test. Sulpiride (10-80 mg/kg i.p.) had different effects, depending on(More)
The effects of benzodiazepines on learning and memory were investigated, using passive avoidance and latent learning tasks, with particular attention being paid to the possible involvement of benzodiazepine receptors and the cholinergic neuronal system. Benzodiazepines such as diazepam, nitrazepam and chlordiazepoxide (CDP) impaired the passive avoidance(More)
The possible involvement of GABAergic neuronal systems in benzodiazepine (BZP)-induced impairment of a passive avoidance response was investigated. Chlordiazepoxide (CDP) impaired passive avoidance when administered prior to training. The CDP-induced impairment was antagonized by pretreatment with picrotoxin, but not by pretreatment with bicuculline or(More)
The effects of apomorphine (0.0125-1 mg/kg, SC), a dopamine (DA) agonist, on passive avoidance learning were assessed in mice which received brief and long foot-shocks in a training test. At low doses, apomorphine stimulates DA autoreceptors. With a shock of brief duration, apomorphine at a low dose (0.05 mg/kg), enhanced the avoidance learning when it was(More)
The effect of phencyclidine (PCP) on latent learning was investigated using a one-trial water-finding task in mice. Mice without water deprivation were given PCP or saline before a training trial, which consisted of exposure to a novel open-field environment with an alcove containing a water tube. Twenty to twenty-four hours after water deprivation, animals(More)
We investigated the involvement of dopamine D1 and D2 receptor subtypes in the effects of GBR 12909, a selective dopamine uptake inhibitor, on latent learning in the performance of a water-finding task and on locomotor activity in mice. GBR 12909 (10 and 20 mg/kg) impaired latent learning, and this effect was counteracted by the dopamine D2 receptor(More)
We examined the involvement of GABAergic neuronal systems in benzodiazepine-induced passive avoidance deficit. Chlordiazepoxide impaired the passive avoidance response dose dependently when it was given prior to training. Post-training administration of muscimol improved the performance of chlordiazepoxide-pretreated mice. The effects of muscimol were(More)
We investigated the effects of nefiracetam (DM-9384), a pyrrolidone derivative, on chlordiazepoxide-, apomorphine-, and methamphetamine-induced impairment of latent learning in a water finding test in mice. Pretreatment with nefiracetam reversed the inhibitory effects of chlordiazepoxide and apomorphine, but not those of methamphetamine, on latent learning.(More)
Our main purpose was to clarify the differences between the effects of dopamine D-1 (SCH 23390) and D-2 (pimozide) antagonists on memory acquisition in a water-finding and a one-trial passive avoidance task with ddY mice. In the water-finding task, pimozide (0.1 and 0.2 mg/kg i.p.) enhanced the acquisition of latent learning of mice although it suppressed(More)