Introduction: Studies have indicated that metformine has different effects on learning and memory. In this study, both acute and chronic therapeutic effects of metformin on memory retrieval and some serum oxidative stress factors in Streptozotocin -induced Alzheimeric male rats were investigated.
Methods: In this experimental study, 48 rats were divided into six groups (n=8) as follows: saline - saline, streptozotocin - saline, and streptozotocin - metformine (once, one week, three weeks and eleven weeks). Intracerebroventricular administrations of streptozotocin (3mg/kg) were done at the first and third day of the surgery. Intraperitoneally administrations of saline (ml/kg) or metformin (200mg/kg) was started one day before the surgery and continued until the end of the care period. The animals’ memory was evaluated through passive avoidance learning; blood serums were used to measure the levels of malondialdehyde, assessment of Ferric Reducing Ability of Plasma (FRAP), levels of superoxide dismutase and catalase enzymes.
Results: Streptozotocin (STZ) significantly reduced the memory retrieval and the levels of FRAP, superoxide dismutase and catalase enzymes and it significantly increased the level of malondialdehyde compared to the control group (p<0/001). Administration of metformin (once, one week and three weeks) improved the memory retrieval and serum oxidative stress factors compared to the STZ group (p<0/001). While the administration of metformin in eleven weeks group did not have any significantly differences compared to the STZ group (p>0/05).
Conclusion: It seems that administration of acute and chronic metformin has different effects on the memory retrieval that it may be due to the effect of chronic metformin in increasing the level of oxidative stress factors in serum.