| ObjectiveVascular dementia(VD)is a dementia syndrome caused by a series of cerebrovascular factors and causes different degrees of damage to brain tissues.The major clinical manifestation of VD is memory loss,indifferent expression,sluggishness and personality changes.It accounts for at least 20% of the total number of dementia.With the aging of the population,the number of patients with vascular dementia is increasing,and it has become a dangerous disease that affects the survival rate of the elderly.Studies have found that transient ischemia hypoxia injury and ischemia-reperfusion injury have the greatest damage to human and animal hippocampal neurons.Hippocampal region is related to cognitive functions such as learning and memory,and it is very sensitive to ischemia and hypoxia.Therefore,the therapeutic research of vascular dementia in recent years is mainly to prevent or reduce the occurrence of apoptosis of nerve cells after ischemia.The phosphoinositide-3-kinase/protein kinase B(PI3K/Akt)signaling pathway is an important signal transduction pathway in cells,which plays an important role in cell survival through a variety of cytokines.?-catenin is an indispensable signaling molecule in the Wnt signaling pathway.It can not only form complexes through adhesion with E-cadherin cells,participate in cell adhesion,but also enter the nucleus,activate transcription factors,and promote cell survival and proliferation.In order to establish a vascular dementia model in rats,we used two-vessel occlusion plus sodium nitroprusside antihypertensive method.To study the expression of PI3 K and ?-catenin in cortical and hippocampal tissues of vascular dementia and the intervention effects of IGF-1 and LY294002.We studied the changes of PI3K/Akt signaling pathway and Wnt/?-catenin signaling pathway in vascular dementia rats,and discussed the mechanism of ischemic neuron cooperative repair.Methods1.Forty-eight healthy male rats of Sprague-Dawley weighed 250–300g.The experimental animals were purchased from the Liaoning Changsheng Biotechnology,and the experimental animal quality certificate number(SCXK(Liao)2015-0001).A model of vascular dementia in rats was made by two-vessel occlusion and sodium nitroprusside hypotension method.Firstly,SD rats were divided into sham group(S group),cerebral ischemia-reperfusion group(I/R group),cerebral ischemia-reperfusion + inhibitor LY294002 group(LY group),cerebral ischemia-reperfusion + IGF-1 group(IGF-1 group),with 12 rats in each group.In the S group,the common carotid artery was isolated without blocking blood vessels.In the LY group,LY294002 was injected into the rats at 0.3 mg/kg through the tail vein 15 minutes before ischemia-reperfusion.In the IGF-1 group,IGF-1 was injected at 14 ?g/kg through the tail vein 1 hour after ischemia-reperfusion in rats,and the S group and I/R group were injected with 1ml of normal saline.2.We used the Zea Longa to screen rat models of vascular dementia.The neurobehavioral scoring method can detect the intervention of IGF-1 and LY294002 on the behavior of VD rats.3.The shuttle box tests the cognitive function of rats in each group.We discuss the effects of cerebral ischemia,IGF-1 and LY294002 on cognitive function in VD rats.4.HE staining was used to detect the histological changes of the cortex and hippocampus,and the intervention of IGF-1 and LY294002.5.To detect expression changes of PI3 K and ?-catenin in cortex and hippocampus after ischemia-reperfusion,and the intervention of IGF-1 and LY294002 by immunochemistry staining.6.Western blot was used for detecting the expression changes of PI3 K and ?-catenin in cortex and hippocampus after ischemia-reperfusion,and the intervention of IGF-1 and LY294002.Result1.Neurological behavior scoring results: The S group had no neurological deficits.zero neurological deficit scores.The neurobehavioral score of the experimental rats in the IGF-1 group was significantly lower than that in the I/R group and the LY group.2.Shuttle box test results: We used shuttle box experiments to test the cognitive function of rats in each group,and to explore the effect of cerebral ischemia on cognitive function in VD rats.Compared with the S group,the avoidance response rates in the I/R group and the LY group decreased,and the avoidance response rate in the LY group decreased more significantly,with a significant difference between the groups.The avoidance response rate of the IGF-1 group increased,which was higher than that of the I/R and LY groups.3.HE staining results: We observed tissue sections of cortex and hippocampus,and evaluated the changes of brain tissue caused by cerebral ischemia-reperfusion injury under light microscope.The number of neurons in S group is large,with neat arrangement and complete morphology.The neurons in the I/R and LY groups were swollen,unevenly distributed,the space around the cells was widened,and some of the cells were reduced in size,and the nuclear contraction was deeply stained.Especially in LY group,the brain tissue damage was more severe and the histological changes were more obvious.Compared with I/R group and LY group,IGF-1 group observed that the number of surviving neurons in cortex and hippocampus increased and the degree of swelling of neuron cells decreased.4.Results of immunochemistry staining: To investigate whether IGF-1 and ischemia-reperfusion activate the PI3K/Akt and Wnt/?-catenin signaling pathways,and detect the expression of PI3 K and ?-catenin after cerebral ischemia-reperfusion in each group of rats.In the S group,PI3 K and ?-catenin were slightly expressed in rat cortex and hippocampus.Compared with the S group,the expression of PI3 K and ?-catenin in the cortex and hippocampus increased in the I / R group The expression of PI3 K and ?-catenin in LY group was lower than that in I/R group.Compared with the I/R group and LY group,PI3 K and ?-catenin in IGF-1 group were significantly increase.5.Western blot test results: Western blot was used to detect the expression of PI3 K and ?-catenin protein after ischemia-reperfusion in each group of rats.IGF-1 and LY294002 can affect the expression of PI3K/Akt and Wnt/?-catenin signaling pathway.Compared with the S group,the expression of PI3 K and ?-catenin in the cortex and hippocampus was increased in the I/R group and the LY group.The expression of IGF-1 group was further increased than that of I/R group and LY group.Conclusion1.IGF-1 promotes cognitive and behavioral damage repair in VD rats.This protective effect will be inhibited by the specific PI3 K / Akt signaling pathway blocker LY294002,suggesting that IGF-1 can activate PI3 K / Akt signaling.Pathways to promote impaired repair of cognitive function in VD rats.2.IGF-1 promotes the survival of ischemic cortex and hippocampal neurons.This protective effect will be inhibited by the specific PI3 K / Akt signaling pathway blocker LY294002,suggesting that IGF-1 works by activating the PI3 K / Akt signaling pathway.3.IGF-1 can activate the PI3 K / ?-catenin signaling pathway in ischemic brain injury,and LY294002 as a PI3 K / Akt signaling pathway inhibitor can effectively inhibit this effect of IGF-1. |
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