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

Previous studies have shown that ascorbic acid (AA) plays a crucial role in mammalian brain as a vitamin and neuronal modulator. There is increasing evidence indicating that dopaminergic system and AA could affect learning and memory processes. In addition، vitamin C acts as a dopamine antagonist in the brain. The aim of the present study was to evaluate the intra-hippocampal co-administration of AA and bromocriptine (Br)، a dopamine D2 receptor agonist، on spatial memory and learning. Adult male rats were trained in Morris Water Maze task. Intra-hippocampal injection was performed through an implanted cannula in the CA1 region. Animals were divided into 12 experimental groups (n=7) including: control، AA 6، 12، 24 and 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. The results 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 and spatial memory as compared to the control and AA groups. These findings indicate that AA could attenuate the effects of D2 dopamine receptors agonist on spatial memory and learning.