Repeated stress increases locomotor response to amphetamine |
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Authors: | Jean-Paul Herman Louis Stinus Michel Le Moal |
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Institution: | (1) Laboratoire de Psychobiologie des Comportements Adaptatifs, INSERM U259, Domaine de Carreire, Rue Camille Saint-Saens, F-33077 Bordeaux, France |
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Abstract: | Adult male rats submitted to mild, 20 min electric foot shock sessions for 10 days displayed an enhanced locomotor response to 0.75 mg/kg (+)amphetamine 24 h after the last shock session, when compared to non-stressed controls. This effect was still present in rats specifically deprived of their forebrain noradrenergic innervation, suggesting the involvement of a dopaminergic mechanism. Cortical and limbic dopamine turnover which increased immediately after acute and repeated foot shocks returned to normal 24 h later, at the time of the pharmacological testing. This fact indicates that a permanent modification of the basal DA activity is not responsible for the above effect apomorphine was enhanced in experimental animals, while hypoactivity resulting from the injection of 0.05 mg/kg apomorphine was similar in control and shocked rats. This latter result suggests the existence of an increased postsynaptic DA sensitivity as a result of repeated stress. |
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Keywords: | Stress Amphetamine Locomotor activity Dopamine Rat |
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