Effect of administration of ascorbic acid and dopamine D2 receptors agonist in the hippocampal CA1 area on spatial learning and memory in adult male rats

Abstract

Previous studies have shown that ascorbic acid (AA) plays a crucial role in mammalian brain as avitamin and neuronal modulator. There is increasing evidence indicating that dopaminergic system and AAcould affect learning and memory processes. In addition, vitamin C acts as a dopamine antagonist in thebrain. The aim of the present study was to evaluate the intra-hippocampal co-administration of AA andbromocriptine (Br), a dopamine D2 receptor agonist, on spatial memory and learning. Adult male rats weretrained in Morris Water Maze task. Intra-hippocampal injection was performed through an implanted cannulain the CA1 region. Animals were divided into 12 experimental groups (n=7) including: control, AA (6, 12, 24and 48 μg/rat), Br (0.5, 1, 2 and 2.5 μg/rat), AA plus Br (24 and 2 μg/rat), AA and Br related sham. Theresults showed that injection of AA caused a significant decrease in both learning and spatial memory.However, administration of Br alone or concomitant with AA caused a significant increase in learning andspatial memory as compared to the control and AA groups. These findings indicate that AA could attenuatethe effects of D2 dopamine receptors agonist on spatial memory and learning.