A Preliminary Study Of Mitochondrial DNA Copy Number And Neural Function Changes In Ischemic Stroke

Objective Ichaemic stroke has sudden onset,short treatment window and poor prognosis,which brings great burden to family and society.Mitochondria are the main organelles from which adenosine triphosphate(ATP)is derived,mitochondrial DNA(mtDNA)copy number plays an irreplaceable important role in the development of ischemic stroke.Mitochondrial DNA(mtDNA)copy number is one of the important markers that can reflect the biosynthesis of mitochondria.Therefore,we hypothesized that mtDNA copy number may be associated with ischemic stroke.This study mainly investigated the changes of mtDNA copy number and mitochondrial function in ischemic stroke,which may provide a new idea for the clinical evaluation and treatment of ischemic stroke.Methods 1.The clinical,animal and cell levels were studied:(1)Clinical grouping:(1)12 cases of normal control group;(2)Ischemic stroke group(12cases).(2)Animal grouping:(1)5 animals in normal control group;(2)Middle cerebral artery occlusion(MCAO)group had 5 animals in 6h and 24 h respectively.(3)Cell grouping:(1)normal oxygen treatment group;(2)Hypoxia treatment group.2.Fresh peripheral venous blood of ischemic stroke patients,inferior venous blood of rats and brain tissue were obtained,and rat cortical neuron cells(RN-C)and mouse hippocampal neuron cells(HT-22)were purchased.By real-time fluorescent quantitative PCR(qPCR)and flow cytometry detection technology to detect mtDNA copy number,mitochondrial membrane potential,reactive oxygen species(ROS)and mitochondrial membrane permeability transition pore(mPTP).Results 1.In the ischemic stroke group,the mtDNA copy number of peripheral venous blood leukocytes was significantly increased,the level of mitochondrial membrane potential and the opening of mPTP were not significantly changed,and ROS was increased.2.The mtDNA copy number of leucocytes in inferior venous blood of rats in MCAO group was lower than that in normal control group(F=244.3,P<0.0001),the mtDNA copy number of MCAO-6h group was significantly decreased,and the mtDNA copy number of MCAO-24 h group was slightly increased than that of MCAO-6h group.The mtDNA copy number in brain tissue of rats in MCAO group was decreased compared with that in normal control group(F = 8.043,P =0.0201),the mtDNA copy number of rats in MCAO-6h group was significantly decreased,and the mtDNA copy number of rats in MCAO-24 h group was significantly increased compared with that in MCAO-6h group.There was no significant change in the level of mitochondrial membrane potential of neurons in the brain tissue of rats in the MCAO group,and no significant change in the MCAO-6h group with mPTP,but the MCAO-24 h group was increased and higher than the normal control group(F=23.74,P<0.0001),ROS of MCAO-24 h group was lower than that of normal control group(F=5.564,P=0.0195);3.The mtDNA copy number and mitochondrial membrane potential level of RN-C in the hypoxic treatment group were significantly lower than those in the normoxic treatment group,and the differences were statistically significant.There was no significant change in mPTP opening,but ROS was increased.The mtDNA copy number,mitochondrial membrane potential level and mPTP opening of HT-22 in hypoxia group were significantly increased,and ROS was decreased.Conclusion In the early stage of ischemic stroke,the body mainly relies on the increase of mitochondrial number and the restoration of mitochondrial function to maintain the physiological function of the brain,and this process may have a short endogenous compensatory repair mechanism.