Resumo

In the present study we investigated the effect of the i.p., intra-NAc, and intra-DLS administration of the D1 receptor agonist SKF 82297 and of the D1 receptor antagonist SCH 23390 on learning of the two-way active avoidance, an aversively motivated conditioned avoidance response (CAR) task. Data were analysed by ANOVA followed by the Newman-Keuls test. SCH 23390 caused a learning impairment that was evident in the session that followed its administration into the NAc (F (2,25) = 10,94, p &le 0.05). However, such impairment was evident only in a second session, carried out 24 h later the administration of SCH 23390 into the DLS (F (2,20) = 6,073, p &le 0.05). The i.p. administration of this drug impaired learning scores in both sessions (F (3,30) = 15,845, p &le 0.05). No effect was observed after the administration of SKF 82297 (i.p.: (F (3,31) = 0,160, p = 0.921; intra-NAc: (F (3,36) = 0,94, p = 0.431); intra-DLS: (F (2,22) = 0,808, p = 0.458)). These results were taken as evidence that, during CAR learning, dopamine is released at an optimal level to activate D1 receptors in the NAc and DLS so that they can mediate, respectively, a fast and slow CAR learning.