Vitamin b12 is a water-soluble vitamin that deficiency leads to the accumulation of homocysteine (an unnecessary amino acid). neuronal damage induced by homocysteine has been shown in some areas of the brain, including the hippocampus involved in the learning process and memory. considering the relationship between low concentration of vitamin b12 and high concentrations of homocysteine with cognitive impairment, the effect of different doses of vitamin b12 on learning and spatial memory in y-maze task in adult male rats was investigated.
Thirty five adult male rats were randomly allocated into four groups: group 1, the control, without any injection; groups 2, 3 and 4, vitamin b₁₂ treatment groups, each group received vitamin b₁₂ (5, 10 or 15 mg/kg, ip daily for ten days) and group 5, vehicle-treated group that received saline (0.2ml, ip daily for ten days) as vitamin b12 vehicle. at the end of the treatment with vitamin b12 or vehicle the rats were trained in y-maze task for five days in order to study spatial learning and twenty five days after training, a retention test was performed to determine long-term memory.
The results showed that treatment with vitamin b12 in groups 10 and 15 mg/kg (p<0.05), significantly improved spatial learning. also, the comparison between vehicle and control groups indicated that there were no significant differences (p>0.05) between these groups that suggested saline had no effect on spatial learning. moreover, no significant difference was observed between the results in the 5th day of training and the memory retention of the 30th day.
The results of this study indicated that intraperitoneal injection of vitamin b₁₂ in doses of 10 and 15 mg/kg for ten days has a positive effect on spatial learning and enhanced the learning in adult male rats in y-maze task.