Effects Of Central Nervous System Mitochondrial Fission And Fusion And Mitochondrial Reinfusion On Inflammatory Pain

Objective: To investigate the changes of mitochondrial fission and fusion in central nervous system under formalin biphasic inflammatory pain.Noduls analysis software was used to accurately evaluate the behavioral changes of mice with acute inflammatory pain,and to explore the effects of changes in central nervous system mitochondrial division and fusion and mitochondrial reinfusion on acute inflammatory pain by detecting the changes in mitochondrial related genes mRNA expression levels.Methods: In this study,adult male C57BL/6J mice were used to create an acute inflammatory pain model using 5% formalin 25 μl.The morphological changes of mitochondria and vacuoles in the central nervous system of formalin pain mice were observed by transmission electron microscopy at 5 min、30 min and 1 h.Mitochondria to the central nervous system back to normal mice and mice formalin,statistical licking foot frequency and time,using video tracking assessment exercise capacity and exploratory behavior in mice,using flow cytometry instrument to detect the activity of the mitochondria,using real-time fluorescent quantitative PCR(qRT-PCR)analysis of the central nervous system changes of mitochondria related genes mRNA.Results: Compared with normal mice,the number of mitochondria in the cerebral cortex of mice with formalin pain group for 5 min decreases,the number of hollow vacuoles in the cerebral cortex of mice with formalin pain group for 30 min and 1 h decreases,and the volume and density of mitochondria and vacuoles in the cerebellum of mice with formalin pain group for 5 min become larger and the relative density decreases.The volume of mitochondria in the spinal cord decreased and the volume and number of vacuoles increase in the 30 min formalin pain group,while the number of mitochondria in the spinal cord increases significantly in the 1 h formalin pain group.Compared with the formalin pain group for 5 min,the volume of mitochondria and vacuoles in the cerebellum of 30 min and 1 h formalin pain groups decreases,the volume of mitochondria in the spinal cord of 30 min formalin pain group decreases,but the area of vacuoles increases.Compared with the formalin pain group for 30 min,the area of spinal cord vacuoles decreases in the formalin pain group for 1h.Mitochondrial membrane potential is detected by flow cytometry,and the results showe that compared with formalin pain group for 5 minutes,the mitochondrial membrane potential is increased in formalin pain group for 30 minutes(the second reaction),and the function of mitochondria is recovered to some extent.After normal mitochondria are reinjected to formalin mice,the pain response is enhanced.In normal mice,the expression levels of Mitochondrial fusion 1(Mfn1)are increased in cerebellar tissue,and Mfn1 and Uncoupling protein 2(Ucp2)are increased in spinal cord tissue.The expression level of Mfn1 in the cerebellar tissue increases after the mitochondria are reinjected to the spinal cord.Mitochondria extracted after 30 minutes of formalin pain are transferred back to formalin mice,and the pain response is relieved.The expression levels of Mfn1 and Mitochondrial transcription factor A(TFAM)in the cerebral cortex,Dynamin-related protein 1(Drp1)and TFAM in the cerebellum and TFAM in the spinal cord are significantly increased after the mitochondria are reinjected to the cerebral cortex.The expression levels of Drp1,Mfn1 and TFAM are significantly increased in cerebral cortex,and Drp1 and Mfn2 are significantly increased in cerebellar tissue,and Drp1 is significantly increased in spinal cord tissue.Conclusion: Mitochondrial fission and fusion of central nervous system are changed in acute inflammatory pain;mitochondrial function is relatively restored during the second phase of pain;mitochondria are extracted from formalin pain for 30 min and then reinjected,which relieve inflammatory pain.