| Research Background and Purpose:Postoperative cognitive dysfunction(POCD)refers to the decline or decline in cognitive function after anesthesia and surgery.These include changes in attention,concentration,orientation,memory,information processing,executive function,visuospatial ability and psychomotor speed.The Mitochondrial calcium uniport(MCU)protein is associated with mitochondrial dysfunction and cell death by controlling mitochondrial calcium uptake,and MCU may play an important role in neurodegenerative diseases.Mineralocorticoid receptor(MR)is related to learning memory and cognitive function.Sevoflurane can cause mitochondrial damage,energy production impairment and cell apoptosis.The pathogenesis of cognitive dysfunction caused by sevoflurane has not been fully elucidated.Sevoflurane may change MCU and cause neuron damage,thus leading to cognitive dysfunction.In order to explore the effect of MCU on cognitive function after sevoflurane anesthesia,POCD model of elderly mice was established by 3%sevoflurane anesthesia,and the influence of MCU on cognitive function was observed,and the relationship between MCU and sevoflurane and cognitive function was discussed,so as to provide a basis for the prevention and treatment of POCD after sevoflurane anesthesia by MCU.The effects of MCU and MR On cognitive function under sevoflurane anesthesia were also investigated.Part I:The effect of MCU on the behavior of aged mice after sevoflurane anesthesiaMaterials and Methods:Thirty-six SPF healthy male C57 aged mice,aged 14 months,were randomly divided into 6 groups:Ruthenium red(MCU antagonist)group(R,n=6),spermine(MCU agonist)group(S,n=6),ruthenium red+sevoflurane group(RA,n=6),spermine+sevoflurane group(SA,n=6),sevoflurane group(A,n=6),and control group(C,n=6).Control group did not do any treatment;Spermine group was intraperitoneally injected with spermine injection 5mg/kg;Ruthenium red group was intraperitoneally injected with ruthenium red injection 6mg/kg;Sevoflurane group inhaled 3%sevoflurane for 3 hours;Spermine+sevoflurane group was intraperitoneally injected with spermine injection 5mg/kg for half an hour and inhaled 3%sevoflurane for 3 hours;Ruthenium red+sevoflurane group was intraperitoneally injected Ruthenium red injection 6mg/kg for half an hour and inhaled 3%sevoflurane for 3 hours.On the first 4 days,all mice were trained in the Morris Water maze positioning navigation experiment.On the fifth day,the mice were given medicine and sevoflurane anesthesia modeling.On the following 7 days,the mice underwent the water maze space exploration experiment to observe the spatial learning and memory ability of the mice and detect the cognitive function.Results:There was no significant difference in activity ability among all groups after 4 days of water maze navigation training(P>0.05).The escape latency of mice in each group was gradually improved with the passage of time in the training stage(P<0.05),indicating that mice formed the spatial memory of the environment around the water maze through training.In addition,no significant differences were observed in escape latency and swimming speed among all groups at the same time point(P>0.05).In the 7-day water maze space exploration experiment,compared with the control group,the frequency of platform crossing in sevoflurane group was lower(P<0.0001),the percentage of target quadrant retention time was shorter(P<0.0001),and the frequency of platform crossing in spermine+sevoflurane group was the lowest(P<0.0001).The percentage of target quadrant dwell time was the shortest(P<0.0001),the target quadrant dwell time of ruthenium red+sevoflurane group was shorter(P<0.05),and there was no significant difference in the frequency of crossing the platform compared with the control group(P>O.05).Conclusion:1.1.5MAC sevoflurane can cause cognitive dysfunction in aged mice;2.Spermine may aggravate cognitive dysfunction in the aged mice after sevoflurane anesthesia,and ruthenium red may alleviate cognitive dysfunction in the aged mice after sevoflurane anesthesia.Part II:The effect of MCU on hippocampal neuron injury in aged mice after sevoflurane anesthesiaMaterials and Methods:Thirty-six SPF healthy male C57 aged mice,aged 14 months,were randomly divided into 6 groups:Ruthenium red(MCU antagonist)group(R,n=6),spermine(MCU agonist)group(S,n=6),ruthenium red+sevoflurane group(RA,n=6),spermine+sevoflurane group(SA,n=6),sevoflurane group(A,n=6),and control group(C,n=6).After behavioral detection,mouse brain tissue was selected for morphological staining and hippocampus tissue protein concentration detection.HE staining was used to observe the morphological changes of neurons in hippocampal CA1 region of mice;Nishi staining was used to observe the morphological changes of neurons in hippocampal CA1 region and the number of Nishi bodies;immunohistochemical staining was used to observe the expressions of MCU and MR In hippocampal CA1 region of mice.The expression levels of MCU and MR Proteins in hippocampus were detected by Western blot(WB).Results:HE staining showed that the number of neurons in the control group was more and arranged neatly.Compared with the control group,the number of neurons in the spermine+sevoflurane group and the sevoflurane group was less and arranged loosely,while the number of neurons in the ruthenium red+sevoflurane group was more and arranged more neatly.At the same time,Nishi staining showed that the structure of neurons in the control group was clear and there were more Nishi bodies.Compared with the control group,the structure of neurons in the sevoflurane group and spermine+sevoflurane group was unclear and there were fewer Nishi bodies,while the structure of neurons in the ruthenium red+sevoflurane group was clear and there were more Nishi bodies.Immunohistochemical results showed that the expressions of MCU and MR Were lower in the control group,increased in the sevoflurane and spermine+sevoflurane groups,but slightly higher in the ruthenium red+sevoflurane group.Western blotting results showed that compared with the control group,MCU and MR In sevoflurane group and spermine+sevoflurane group were increased(P<0.0001),MCU expression in ruthenium red+sevoflurane group was increased(P<0.0001),and MR Expression in ruthenium red+sevoflurane group was slightly increased(P<0.05).Conclusion:1,1.5MAC sevoflurane could induce high expression of MCU,and was positively correlated with hippocampal neuron injury.2.Spermine may aggravate hippocampal neuron damage induced by sevoflurane,and ruthenium red may alleviate hippocampal neuron damage induced by sevoflurane;3.Synchronous high expression of MCU and MR in POCD aged mice successfully modeled by sevoflurane. |
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