Optogenetic Stimulating Of Medial Prefrontal Cortex Promotes Cognitive Improvement In Vascular Cognitive Impairment And Its Mechanism

Background: Vascular cognitive impairment(VCI)is the second leading cause of dementing illness,and it is related to white matter damage which is caused by chronic hypoperfusion led by intracranial small blood vessel or macrovascular disease.However,the pathogenesis of VCI is not clear,and there is still no effective clinical therapy.It’s urgent to explore the potential pathogenesis and therapy of VCI.Studies have found that chronic hypoperfusion mainly causes myelin impairment in the white matter area.Neuronal activity could promote myelin remodeling,and optogenetics could control neuronal electrical activity in awake and moving freely animals.Therefore,the purpose of this study was to explore the treatments and potential mechanisms of repairing damaged white matter and improving cognitive function in vascular cognitive impairment model mice by optogenetics.Methods: C57BL/6 mice were performed bilateral common carotid artery stenosis(BCAS)model.Then,after one and two months,the memory impairment was determined using fearing conditioning tests and Y-Maze tests,T-Maze tests,white matter lesions and myelin integrity in the corpus callosum(CC)were evaluated using Black-Gold Staining,immunofluorescence,western blot,RT-PCR and transmission electron microscope (TEM).After that,the brain regions related to impaired memory were explored using virus-mediated c-fos neuronal labeling strategy and fiber photometry system monitoring in vivo calcium(Ca2+).Then,immunofluorescence and patch clamp technology were performed to explore whether the brain regions associated with impaired memory were damaged.After that,virus-mediated neuronal labeling strategy was developed to find the connectivity between damaged brain regions and CC.Then,optogenetic stimulation was used to selectively activate neurons in the damaged brain areas.And behavior tests were performed again to determine the improvement of memory in BCAS model mice treated with optogenetics.Then,Black-Gold Staining,immunofluorescence,western blot,RT-PCR and TEM were used to evaluate improvement of white matter in the projections from the damaged brain areas entering the CC.At last,m RNA chips were developed to screen out genes differentially expressed in damaged brain regions after optogenetic treatment to explore specific mechanisms.Results: 1)In month 2 after BCAS surgery,the short-term working memory was impaired,myelination in CC was blocked,and the excitatory of glutamatergic neurons in the media prefrontal cortex(m PFC)reduced.2)Optogenetic stimulation of glutamatergic neurons in the m PFC of BCAS model mice could improve short-term working memory,promote myelin remodeling,white matter repair,and there was strong positive correlation between the improvement of working memory and the repairment of white matter.3)Optogenetic stimulation of glutamatergic neurons in m PFC of BCAS model mice could up regulate the genes for oligodendrocytes’ proliferation,differentiation,maturation,and migration and down regulate the genes damaging myelin’s function and causing demyelinating disease.Conclusions: Optogenetic stimulation of glutamatergic neurons in m PFC of BCAS model mice could promote myelin remodeling,white matter repair and improve short-term working memory.