BACKGROUND AND OBJECTIVE: Ascorbic acid has a wide range of functions in the central nervous system such as neuromodulator and antioxidant. Ascorbic acid intervenes with the neurotransmitters involved in learning and memory. In this study, we examined the effects of its injection and its removal enzyme in the hippocampal CA1 region on spatial learning and retention.

METHODS: We used 49 Wistar rats in this study (220-270 mg/kg) and we divided them into seven groups including: control, sham (recipients of solvent), ascorbate oxidase (0.2, 0.4 µg/kg), ascorbic acid (24, 12µg/kg), and inactive ascorbate oxidase (0.2 µg/kg). Bilateral cannula was performed in the hippocampal CA1 region using stereotaxy device. After one week of recovery, one microliter of the drugs was injected by a Hamilton syringe. Spatial learning and retention was measured by using the Morris water maze.

FINDINGS: The results show that 12 µg/kg dose of ascorbic acid increases mileage (1012.98±63.55) and escape latency (55.48±2.38) compared to the control group (633.33±18.46) (45.9±1.84) (p<0.05). Also mileage (1123.73±108.89) and escape latency delay (57.31±1.18) were raised with 24 µg/kg dose of ascorbic acid compared to the control group (p<0.01). It was determined that ascorbate oxidase with both 0.2µg/kg (p<0.01) and 0.4µg/kg (p<0.001) dose increased the mileage and escape latency compared to the control group.

CONCLUSION: The results showed that the injection of ascorbic acid and its removal enzyme in the hippocampal CA1 region leads to spatial learning and retention loss.