Comparative effects of alpha-2 receptor agents and THA on the performance of adult and aged rats in the delayed non-matching to position task |
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Authors: | Jouni Sirviö Maija Harju Paavo Riekkinen Jr Antti Haapalinna Paavo J Riekkinen |
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Institution: | (1) Department of Neurology, University of Kuopio, P. O. Box 1627, SF-70211 Kuopio, Finland;(2) Orion Corporation Farmos, R&D Pharmaceuticals, SF-Turka, Finland |
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Abstract: | The present study investigated the effects of dexmedetomidine (an alpha-2 adrenoceptor agonist), atipamezole (an alpha-2 adrenoceptor antagonist) and tacrine (an inhibitor of acetylcholinesterase) on the performance of adult and aged rats in a delayed non-matching to position task assessing spatial short-term memory. Most of the aged rats were impaired in the pretraining phases and in the acquisition of the non-delayed version of the task. After a substantial training period of the delayed version of the task, both adult and aged rats reached their asymptotic level of performance. Both adult and aged rats showed a decline in the percent correct responses at the longest delays in this task, and a delay independent decrease in the percent correct responses across the delays (0–30 s) was found in the group of aged rats (25-month-old) as compared to the adults (10-month-old). Dexmedetomidine (0.3, 1.0 or 3.0 µg/kg), atipamezole (0.03, 0.3 or 3.0 mg/kg) and tacrine (1.0 or 3.0 mg/kg) did not increase the percent correct responses in adult or aged rats. The highest doses of dexmedetomidine and tacrine decreased behavioural activity of rats during this short-term memory testing. Atipamezole (0.03 mg/kg) increased behavioural activity of rats. The results suggest that acute, systemic administrations of alpha-2 drugs or an anticholinesterase do not improve short-term memory in rats. |
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Keywords: | Short-term memory Aging Noradrenergic system Alpha-2 adrenoceptors Cholinergic system Rat |
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