| Objective:To investigate the mechanism of Grb10 / IGF-1R signaling pathway in attenuating cognitive function of STZ-induced diabetic encephalopathy rats under the intervention of treadmill.Method:Experimental animals were grouped and modeled: 30 male SD rats of 2 months old with a body weight of 160±20 g were adopted.After one week of adaptive feeding,they were randomly divided into 10 control group(NC)and 20 diabetes model group(DM)according to body weight.In the DM group,4 weeks of high fat diet combined with STZ injection was used to make the model.After weighing each rat,STZ was intraperitoneal injected at a dose of 25 mg/kg,while the NC group rats were intraperitoneally injected with the corresponding dose of citric acid buffer after weighing.Rats with successful modeling can be randomly divided into diabetes group(DM group)and diabetes exercise intervention group(DM+Exe)each 10.The rats in the DM+Exe group exercised on a non-slope treadmill for 40 minutes at 8pm every night at a speed of 12 m/min,and exercised 5 times a week for 8 weeks.Take a day off after exercise intervention to conduct a 6 day Morris water maze test experiment to observe the behavioral performance of rats.After the experiment,the rats were sacrificed under anesthesia,and the brain,hippocampal and cortical tissues were quickly stripped off on the ice.The hippocampus and cortical tissue were immediately stored in liquid nitrogen,and the whole brain was fixed in the 4% paraformaldehyde solution for 12-24 h.Nissl staining was used to observe the morphological changes of neurons in hippocampus of rats;Western blot was used to detect the expressions of AD-like pathological proteins,synaptic plasticity-related proteins,Grb10 / IGF-1R / PI3 K / AKT / ERK / GSK-3β signaling pathway-related proteins,mTOR / AMPK proteins,apoptosis related-proteins and glucose transporters in the hippocampus and cortex of rats.NeuN staining was used to observe the expression of mature hippocampal neurons in rats.To detect the degree of cognitive impairment and the intervention effect after exercisein diabetic rats,and to elucidate the molecular mechanism of exercise intervention in alleviating cognitive impairment in diabetic encephalopathy rats.Results:1.The diabetic rat model was successfully established.Compared with the NC group,the weight of the DM group rats was significantly reduced(p <0.05),and the blood glucose level of the DM group rats was also increased(p <0.001),and they showed symptoms of polydipsia,polyphagia and polyuria.It can be seen that the diabetic rat model was successfully established.In the DM+Exe group,the symptoms of diabetes were reduced and the blood glucose level was lower than that in the DM group(p <0.05),indicating that treadmill exercise can improve the symptoms of diabetes.2.The behavioral results of 1-5 days showed that the latency of finding a platform in the DM group was significantly longer than that in the NC group,and the number of times of crossing the platform on the 6th day was less than that in the NC group.It indicates that diabetic rats have cognitive dysfunction.The treadmill shortens the escape latency of DM rats,increases the number of times they cross the platform(p <0.05),and improves cognitive dysfunction caused by diabetes.3.Nissl staining results showed that the Nissl bodies in hippocampal CA1,CA3,and DG regions of STZ-induced diabetic encephalopathy were arranged neatly and the structure was normal;but the Nissl bodies in hippocampal region of DM group were disordered and irregular in shape.It is suggested that hippocampal neurons of STZ-induced diabetic rats are damaged.The 8-week treadmill intervention restored hippocampal neuron damage.4.Compared with NC group,the expression of Aβ,BACE1 and PHF10 protein in hippocampus of DM group was significantly increased.However,treadmill exercise intervention reduced the expression of these proteins in STZ-induced diabetic rats,indicating that treadmill exercise can reduce the expression of AD-like pathological proteins in the hippocampus of diabetic encephalopathy rats.5.Compared with the NC group,the synaptic plasticity-related proteins in the hippocampus and cortex of the DM group: protein levels of SYN,PSD-93 and PSD-95 decreased significantly.It showed that the synaptic plasticity of hippocampus and cortex was damaged in diabetic encephalopathy rats.The DM+Exe group reversed the abnormal decrease in synaptic plasticity in the hippocampus and cortex of DM rats.6.Compared with the NC group,the expression of Grb10 protein in the hippocampus and cortex of the DM group was significantly increased,and the expression of IGF-1Rβ was reduced.However,treadmill exercise can reduce the abnormal increase of Grb10 protein in the hippocampus and cortex of diabetic encephalopathy rats and increase the expression of IGF-1R.7.The IGF-1R / PI3 K / AKT / ERK / GSK-3β signal in the hippocampus of the DM group is inhibited.And treadmill exercise intervention can up-regulate PI3 K / AKT / ERK / GSK-3β signaling pathway in hippocampus of diabetic encephalopathy rats.8.Compared with the NC group,the phosphorylation levels of mTOR(ser2448)and AMPK(Thr172)in the hippocampus of the DM group were decreased,and treadmill exercise intervention could increase the phosphorylation levels of mTOR and AMPK in the hippocampus of the diabetic encephalopathy rats.9.Compared with the NC group,the positive cells of the hippocampal NeuN in the DM group were loosely arrangedand the expression of NeuN was significantly reduced.This indicates that hippocampal neuron loss is increased in diabetic encephalopathy rats.However,after 8 weeks of treadmill training,rats in the DM+Exe group increased NeuN staining positive cells.Compared with the NC group,the expression of anti-apoptotic protein Bcl-2 in the hippocampus and cortex of the DM group decreased,and the expression of the proapoptotic protein Bax increased,while treadmill intervention can significantly reduce hippocampal and cortical cell apoptosis in diabetic encephalopathy rats.10.Finally,we found that the expression of GLUT4 in the hippocampus of the DM model group was lower than that in the NC group,that is,glucose transport disorder in diabetic encephalopathy rats.However,treadmill exercise intervention significantly increased the level of GLUT4 protein in hippocampus of DM rats,indicating that treadmill exercise improved the transport of GLUT4 protein in hippocampus of diabetic encephalopathy rats.Conclusions:Treadmill training can improve the cognitive impairment caused by diabetes,mainly by regulating the Grb10 / IGF-1R signaling pathways. |
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