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Several studies have recently shown that basal and stress-induced secretion of corticosterone may enhance vulnerability to drugs of abuse. In this report, we studied the effects of metyrapone, an inhibitor of the synthesis of corticosterone, on cocaine-induced locomotion and on the relapse of cocaine self-administration. Locomotor response to cocaine was(More)
It has been shown that rats, like humans, display individual differences in the propensity to develop psychostimulant self-administration. Animals showing the highest locomotor reactivity to novelty (HRs: High Responders) are more prone to develop amphetamine self-administration than rats having a low locomotor response to novelty (LRs: Low Responders). The(More)
The neurobehavioral responsivity to peripherally injected muscimol, a gamma-aminobutyric acid-A (GABA-A) agonist, was assessed in infant (14-day-old), weanling (20-day-old) and young adult (53-day-old) outbred male mice. In the first experiment, relatively high doses of muscimol (ranging from 0.05 to 0.40 mg/kg in developing and from 0.50 to 3 mg/kg in(More)
Previous studies have shown that different components of behavioral effects of indirect agonists given chronically to laboratory rodents can follow different courses during treatment. Whether repeated injections of a D2 agonist can lead to the same phenomenon was investigated in mice using the D2 agonist(More)
Inhibition of ethanol tolerance by oxytocin has been demonstrated previously using the hypothermic effect only. The purpose of the present experiment was to investigate the effect of oxytocin on the development of tolerance to ethanol-induced hypothermia, myorelaxation and akinesia in mice. Four groups of mice received daily intraperitoneal injections of(More)
The present study tested the hypothesis that the attenuation by oxytocin of tolerance to ethanol-induced hypothermia relies upon an impairment of the putative conditioning processes underlying environment-specific tolerance. According to the conditioning model of tolerance, such tolerance occurs because an opposite compensatory response conditioned to(More)
The present experiment assessed the extent to which environmental stimulation could influence tolerance to the sedative and catatonic effects of the GABAA agonist, 4,5,6,7-tetrahydroisoxozolo(5,4-c)pyridin-3-ol (THIP), through associative learning processes. A conditioning paradigm was used, with THIP as unconditioned stimulus and environmental cues as(More)
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