Correlation Between TRPC3 And Blood Brain Barrier During Aβ Clearance In Mice With Alzheimer’s Disease

ObjectiveIn this study,specific agonists and inhibitors of transient receptor potential canonical 3（TRPC3）were respectively applied to observe behavioral changes in mouse model of Alzheimer’s disease,changes in the levels of β-amyloid protein（Aβ）in serum and hippocampus,changes in the permeability and function of the blood brain barrier,and the expression level of low density lipoprotein receptor-related protein-1（LRP-1）,Aβ trans blood brain barrier transporter,to explore the role of TRPC3 channel in Aβclearance,and the relationship between TRPC3 channel and blood brain barrie in Aβclearance.Methods1.Sixty 5-week-old male ICR mice were randomly divided into sham operation group,model group,OAG group and PYR3 group,with 15 mice in each group.Mice in the model group,OAG group and PYR3 group were injected with Aβ1-42 into the lateral ventricles of mice induced by Alzheimer’s disease,and mice in the sham operation group were injected with the same amount of sterilized normal saline into the lateral ventricles.On the same day,OAG group was intraperitoneously injected TRPC3 agonist OAG（1-oleoyl-2-acetyl-sn-glycerol）,and PYR3 group was intraperitoneally injected with TRPC3 inhibitor PYR3 [ethyl-1-（4-（2,3,3-trichloroacrylamide）phenyl）-5-（Trifluoromethyl）-1H-pyrazole-4-carboxylate],once a day at a fixed time,for consecutive 21 days.2.Morris water maze test was used to test the spatial learning and memory ability of mice in each group.3.Blood brain barrier tracer Evans Blue was intravenously injected to determine the dye concentration in the brain tissues,to measured the blood brain barrier permeability in each group of mice.4.Western blotting was used to detect the expression of tight junction protein,namely zonula occluden-1（ZO-1）of blood brain barrier in each group of mice.5.Western blotting was used to detect the expression of Aβ trans blood brain barrier transporter protein LRP-1 in each group of mice.6.The concentrations of Aβ1-42 in serum and hippocampus were determined by ELISA in each group of mice.Results1.Morris water maze test results showed that compared with the sham operation group,the escape latency of mice was significantly longer on day 4 and day 5（P<0.001;P<0.001）,the dwell time of target quadrant and the number of crossing platform was decreased on day 6（P<0.001;P<0.001）in the model group.Compared with the model group,the escape latency of mice was shortened on day 4 and day 5（P<0.05;P<0.05）,the dwell time of target quadrant and the number of crossing platform was increased on day 6（P<0.05;P<0.05）in OAG group.Compared with the model group,mice in PYR3 group had no significant difference in escape latency on day 4 and day 5,and the dwell time of target quadrant and the number of crossing platform on day 6.2.Evans blue vein perfusion test showed that compared with the sham operation group,the content of Evans blue in the brain tissue of model group was increased（P<0.05）,and the blood brain barrier permeability was increased.Compared with model group,the content of Evans blue in the brain tissue of mice was decreased（P<0.05）,the blood brain barrier permeability was decreased in OAG group,while there was no statistical difference in Evans blue content in the brain tissue of mice in PYR3 group.3.Western blotting detection results of ZO-1 showed that compared with sham operation group,the expression of ZO-1 protein of mice in model group was decreased（P<0.01）,blood brain barrier permeability was increased and function was impaired.Compared with model group,the expression of ZO-1 protein of mice in OAG group was increased（P<0.05）,blood brain barrier permeability was decreased and function was recovered,while the expression of ZO-1 protein of mice in PYR3 group had no statistical difference.4.Western blotting detection results of LRP-1 showed that compared with the sham surgery group,the expression of LRP-1 protein of mice in model group was decreased（P<0.01）.Compared with the model group,the expression of LRP-1 protein of mice in OAG group was increased（P<0.05）,while the expression of LRP-1 protein of mice in PYR3 group had no statistical difference.5.The results of Aβ1-42 concentration determined by ELISA showed that compared with the sham surgery group,the concentrations of Aβ1-42 in serum and hippocampus of mice in model group were increased（P<0.05;P<0.01）.Compared with the model group,the concentration of Aβ1-42 in serum of mice was increased（P<0.05）,the concentration of Aβ1-42 in hippocampus of mice was increased（P<0.05）in OAG group.Compared with the model group,the concentration of Aβ1-42 in serum of mice in PYR3 group was increased（P<0.01）,and there was no significant difference in the concentration of Aβ1-42 in hippocampus.ConclusionIn mouse model of Alzheimer’s disease,the TRPC3 channel may improve behavioral symptoms of Alzheimer’s disease by up-regulating the protein expression of ZO-1 and LRP-1,restoring blood brain barrier permeability and function,and accelerating the clearance of Aβ deposition in brain tissues.