Effects of insulin on NMDAR and synaptic plasticity in hippocampus of rats with vascular dementia

【Objective】 To investigate the effects of insulin on hippocampus NMDA receptor(NMDAR)and synaptic plasticity in the rats with vascular dementia.【Methods】 60 male Sprague-Dawley rats were randomly assigned to a treating group(n =20),a model group(n =20),and a sham-operation group(n =20).The rats in the former 2 groups were operated on to establish the experimental vascular dementia model by bilateral common carotid artery permanent ligation.Insulin was injected intracerebroventricularly in treating group,and saline was injected intracerebroventricularly in model and sham-operation group.The rats' learning and memory were assessed at 4 weeks after operation.Immunohistochemical staining was used to detect NMDAR expression in hippocampus.Western blotting was used to detect NMDAR and synaptophysin.【Results】The rats in treating group showed significantly better learning ability than model group(P 0.05).At the first day after operation,the grey level of NMDAR in the hippocampus of the rats for the model group is(110.28 + 13.67),(125.44 + 8.35)for the treating group and(145.12 + 17.23)for the sham-operation group,with obvious differences among the groups(F =16.54,P 0.05).The expression level of NMDAR of treating group is 1.48 times as sham-operation group(P 0.05),the expression level of NMDAR of model group is 2.28 times as sham-operation group(P 0.05).At 35 days after operation,the grey level of NMDAR in the hippocampus of the rats for the model group is(170.79 + 11.13),(155.63 + 13.48)for the treating group and(139.12 + 18.25)for the sham-operation group,with obvious differences among the groups(F =11.79,P 0.05).The expression level of NMDAR of treating group is 0.72 times as sham-operation group,model group is 0.48 times as sham-operation group(P 0.05).The expression level of synaptophysin of treating group is 0.72 times as sham-operation group,and model group is 0.46 times as sham-operation group(P 0.05).【Conclusion】Insulin ameliorated cognitive ability of rats with vascular dementia,and the mechanism possibly is related to modulate expression of NMDAR and synaptophysin in the hippocampus of rats with vascular dementia.