Efeito da administração aguda e repetida de fencanfamina sobre o valor reforçado do estímulo / Effect of acute and repeated administration of Fencamfamine on reinforcement value of stimuli.

AUTOR(ES)

Miriam Garcia-Mijares

DATA DE PUBLICAÇÃO

2000

RESUMO

Fencanfamina (FCF) is an indirect dopaminergic agonist with neural and behavioral effects similar to those observed for other stimulant drugs such as the amphetamine or cocaine (COC). The aim of the present investigation was to evaluate the effect of acute and repeated administration of FCF on the reinforcing value (Re) taken as a motivational index. The Herrnstein hyperbole equation (1970) was used to evaluate this motivacional effect. The effects of FCF on response rate and motor capacity (k) where also observed. Three experiments were conducted. In all of them the effect of FCF was tested on rats trained on seven VI multiple schedule. In Experiments 1 and 2 (E1 and E2, respectively) three acute doses of FCF (0.88 mg/kg, 1.75 mg/kg and 3.5 mg/kg) were administered (i.p.) The reinforcer was water (E1) or sacarose (E2). In both experiments, the effect of the drug on the parameters studied was similar: the three doses of FCF increased the response rate, decreased Re and had no effect on k. In Experiment 3, six injections of vehicle (VEI Group) or 1.75 mg/kg of FCF (DROGA Group) were intermittently administered (i.p.) in order to promote sensitization. Seven days after drug withdrawal a single dose of 0.88 mg/kg of FCF was administered to animals in both groups and the effect on response rate, k and Re was measured. Results showed that repeated administration of FCF did not change the effect of this drug on the parameters investigated. These results are consistent with the evidence showing that FCF has behavioral effects similar to those reported for other stimulants and support the interpretation that increases in response rate are primarily related to changes in reinforcing value. Thus they probably reflect a motivational effect of the drug. Moreover, the results support the hypotheses that associate the dopaminergic system to the process of reinforcement. It is speculate that the failure to obtain sensitization after repeated administration of FCF could be related to dosage or number of injections.

ASSUNTO(S)

droga (abuso) desempenho motor esquemas de reforço cns stimulating drugs psicofarmacologia rats drug abuse fencanfamina motivação ratos choice behavior psychopharmacology fencanfamine drogas estimulantes do sistema nervoso central reinforcement schedules comportamento de escolha motor performance motivation

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