Tehran University Medical Journal

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Background: Nucleus accumbens (NAc) and prefrontal cortex (PFC) dopaminergic and glutamatergic systems are involved in regulating of locomotor activity behaviors. This study has investigated the interaction of NAc shell dopaminergic system and prelimbic glutamatergic systems in regulating locomotor activity and related parameters.
Methods: The aim of this study was the effect the drugs injection interaction in the brain of male Wistar rats on locomotor activity and related parameters, in the order of this purpose, open field apparatus that automatically recorded locomotor activity was employed. Unilateral intra-cerebral injection of drugs was done.
Results: Unilateral intra-prelimbic injection of D-AP7 (N-methyl-D-aspartic acid= NMDA receptor antagonist 0.25, 0.5 and 1μg/μl) did not alter locomotor activity behaviors. However, infusion of NMDA (0.9μg/μl) in this region increased locomotor activity (P<0.01), whereas decreased rearing (P<0.01) and grooming (P<0.01) which was blocked by D-AP7 (0.25μg/μl) (P<0.01). Moreover, unilateral infusion of SCH23390 (dopamine D1 receptor antagonist 0.25, 0.5 and 1μg/μl) into the left NAc shell did not alter locomotor activity. However, injection of SKF38393 (dopamine D1 receptor agonist 4μg/μl) into the left NAc shell increased locomotor activity (P<0.05) which was blocked by SCH23390 (0.25μg/μl) (P<0.01). Furthermore, the subthreshold dose infusion of SCH23390 (0.25μg/μl) into the left NAc shell reduced the effect of intra- prelimbic NMDA on locomotor activity (P<0.01). In addition, intra-NAc shell administration of the subthreshold dose of SKF38393 (1μg/μl) potentiated the middle dose (P<0.05), whereas decreased the higher dose of intra-left prelimbic NMDA response (P<0.05) on locomotor activity.
Conclusion: The results suggested a modulatory effect of the NAc shell dopaminergic system on increased locomotor activity by activating glutamate system in prelimbic.