The acute and chronic effects of metformin on memory retrieval and hippocampal CA1 area intact neurons in streptozotocin-induced Alzheimeric male rats

In this study, both acute and chronic therapeutic effects of metformin on memory retrieval and the number of intact neurons of hippocampal CA1 area in streptozotocin-induced Alzheimeric male rats were investigated. 48 Male Wistar rats weighing 220-250 g were divided into six groups: control group (saline-saline), streptozotocin group (streptozotocine-saline), treated groups with streptozotocin plus metformin for once, one week, three weeks, and eleven weeks. ICV administration of STZ (3mg/kg) was down in the first and the third day of surgery and i.p injection of metformin (200mg/kg) or saline (ml/kg) daily starting one day before surgery to the end of care period. After the memory test, the animals were killed and their brains were fixed and density of intact neurons in the CA1 area of the hippocampus was investigated. Statistical analysis was performed with software SPSS, ANOVA and software Prisme. The ICV injections of STZ significantly reduced memory retention and the number of intact neurons compared to the control group (p<0/001). The use of metformin in once, one week and three weeks improved the effects of STZ (p<0/001). But metformin in eleven weeks treatment period don’t have significant effect on memory retrieval and the number of intact neurons in hippocampal CA1 area compared to the STZ group (p>0/05). Both acute and chronic metformin uses have different effects on memory retrieval and the number of intact hippocampal CA1 area neurons