[ Effect of Metformin on spatial learning and memory in streptozotocin Rat Model of Alzheimer's Disease]

Background:Alzheimer's disease [AD] is closely associated with impaired insulin signaling in brain, suggesting it to be a brain-specific form of diabetes and so termed as "type 3 diabetes". Therefore investigating the role of pharmacological agents that can improve neuronal insulin resistance merit attention in treatment off AD. Metformin is one of the most widely used against peripheral insulin resistance. In present study, we aimed to investigate the therapeutic efficacy of metformin on spatial learning and memory of streptozotocin [STZ] Rat Model of AD.

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Materials and Methods: 56 Female wistar rate [200-250gr] were divided into 6 groups [n=6]: control, sham operated, STZ, STZ +Saline [0.2ml], STZ +Metformin [50, 100, 200mg/kg, i.p. for 10 day]. For induction of AD, STZ [3 mg/kg,] were administered bilaterally into latral ventricles. All rates were tested spatial learning and memory in the Morris water maze.

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Results: our results show that pre-training injection of Metformin improves spatial learning and memory in STZ Rat Model of AD in a dose dependent manner, so that rats of Metformin groups found platform in less time and with less distance traveled, in comparison with STZ group. Metformin also increased the percentage of time elapsed and the distance swum in the target quadrant in STZ Rat Model of AD, in probe test.

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Conclusion: An i.c.v. injection of STZ resulted in a significant decline in spatial learning and memory and pretreatment with Metformin can enhance spatial learning and memory. The results show that metformin as an insulin sensitizer against peripheral insulin resistance is useful for AD treatment.