Modification of 8-OH-DPAT effects on learning by manipulation of the assay conditions.
A role for the 5-HT1A receptor in learning and memory has been suggested by diverse evidence. The present paper deals with the acute effect of 8-OH-DPAT (a 5-HT1A agonist) administered to rats before or after training in an autoshaped lever-press response (a model of associative learning). The results show that 8-OH-DPAT improved consolidation of the conditioned response (CR) when injected post-training, but impaired it with pretraining administration. Both effects were time-dependent. When the compound was administered pre- or post-training to free-feeding or prefeeding animals, they did not learn the CR. When it was administered to retrained food-deprived animals, the compound was also inactive. However, with retrained animals on a free-feeding schedule, pre- or post-training administration of 8-OH-DPAT enhanced retrieval in a dose-dependent fashion. Pretraining administration of 8-OH-DPAT impaired food intake and exploration, and therefore learning. The present results strongly suggest a role of 5-HT1A receptors in the consolidation and retrieval of learning. Such improvement is independent of food intake.
Meneses
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Terapéutica Experimental, Departamento de Farmacología y Toxicología, CINVESTAV-IPN, México.
Hong
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D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D003213:Conditioning, Psychological / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D005106:Exploratory Behavior / Q000187:drug effects; D007858:Learning / Q000187:drug effects*; D008297:Male; D008568:Memory / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*
D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin