Correlation Between N-Cadherin And Nerve Injury In The Rat With Delayed Encephalopathy After Acute Carbon Monoxide Poisoning

BackgroundsExcessive carbon monoxide(CO)gas absorbed by human body will not only cause acute fatal poisoning,but also cause delayed encephalopathy after acute carbon monoxide poisoning(DEACMP).Demyelinating nerve injury is one of the main pathological manifestations of the disease,and it is also an important reason for the poor prognosis of the disease.It has been reported that N-Cadherin or its related signaling pathway can affect the migration of oligodendrocytes,thus leading to the impairment of demyelinating nerve repair.It is suggested that N-Cadherin or N-Cadherin correlated signaling pathway is related to demyelination and other nerve injury.ObjectivesIn this study,DEACMP rat model was established by means of modified intraperitoneal injection of CO,and model conformity was evaluated with behavioral tests,such as Y maze,open field test,new object recognition test,wheel fatigue test,etc.And the pathological changes of nerve injury were used to evaluate the rat model conformity?The dynamic expressions of myelin basic protein(MBP),a molecule related to nerve injury,as well as N-cadherin in the DEACMP rat model were studied,in order to investigate the correlation between N-Cadherin expression at targeted brain area and pathogenesis of DEACMP demyelination,and thus,To provide a new therapeutic target for the prevention or reduction of demyelinating nerve injury.Methods1.60 SPF grade male SD rats with weight of 280 ± 20 g were randomly divided into model group(AC group,n = 48)and control group(NC group,n = 12),and model group was divided into 4 subgroups according to four different time-points of 1w,2w,3w and 4w after CO poisoning(n=12).Adaptive feeding was carried out for one week in individual ventilated cages(IVC)without water&food restriction.2.DEACMP rat model was established by modified intraperitoneal spacer injection of CO.The rats in model group were intraperitoneally injected with high concentration of CO gas(99.99%,110ml/kg)at 08:00 am,followed by another injections of CO gas(99.99%,55ml/kg)every other 4 fours(a total of 3 times).The control group was injected with the same amount of air.The behavior was observed after acute CO poisoning and within 4 weeks after waking.3.At different time-points of 1w,2w,3w and 4w after CO poisoning,the learning and memory,mental state and motor ability of SD rats in each group were detected by Y maze,open field,new object recognition,rotary fatigue instrument and other behavioral methods.4.q-PCR was used to detect m RNA expression of N-Cadherin and MBP genes in frontal lobe and striatum of rats at different time-points.5.Western blotting was conducted to detect expression of N-Cadherin and MBP proteins in the frontal lobe and striatum of rats at different time-points.6.HE staining was used to detect the neuropathological changes in experimental rats and observe the changes of neuron injury in the brain tissue of rats.7.The experiment results were expressed as mean ± standard deviation(sx±),and statistical analysis was conducted by SPSS21.0 software;independent sample t test was used for subgroup comparison in model group and control group;one-way ANOVA analysis was used for multiple sample comparison;minimum difference of significance test was used for comparison at each time period in two groups(test level =0.05).Significant difference was noticed once P<0.05.Results1.Most of rats in model group demonstrated symptoms of acute carbon monoxide poisoning 10 min to 30 min after intraperitoneal injection of CO gas,such as shortness of breath,irritability and hyperactivity;opisoptonous inversion,and cherry red spots on skin or mucous membrane were also seen in some rats.2.Behavioral tests results:(1)Y maze test showed that the time of exploring new and different arms in model group was significantly shorter than that in control group,and time-shortening in 1w,2w and 3w groups was significantly significant(P<0.05).(2)Open-field results showed that total movement distance in model group was not significantly different than that in control group(P>0.05),but the groups of 2w and 3w in model group had a decreasing trend compared with control group and other groups.(3)New object recognition results showed that new object discrimination index in 1w,2w and 3w groups in model group gradually decreased,it was the lowest in 3w group,and significantly increased in 4w group;and the differences between 2w group and 3w group and control group and 4w group were statistically significant(P<0.05).(4)Rota rod results showed that average activity time in 1w,2w,3w and 4w groups of model group gradually decreased,and differences between model group and control group were statistically significant(P<0.05).3.Western blotting results showed that N-Cadherin and MBP were expressed in prefrontal lobe and striatum brain regions of rats in model group and control group.Expression of MBP in 1w,2w and 3w rats in model group gradually decreased,it reached lowest in 2W group and significantly increased in 4W group;,and significant differences were noticed between 2w and 3w subgroups and control group(P<0.05).N-Cadherin expression in 4 subgroups of model group increased gradually,with the highest level in 3w,but a significant decrease in 4w;and the differences between 2w and 3w rats and control group were statistically significant(P<0.05).4.q-PCR results showed that N-cadherin-m RNA and MBP-m RNA expressed at frontal lobe and striatum both in model group and control group,and N-Cadherin-m RNA expression in model group all significantly increased(P<0.05),with highese level in 3w group at frontal lobe and in 1W at striatum.5.The results of HE staining showed that neuronal degeneration and necrosis appeared in the hippocampus region tissue of rats in the model group.Conclusion1.DEACMP rat model was obtained with modified intraperitoneal spacer injection CO method with high success rate and clinical compliance.2.The DEACMP rat model showed typical neuron injury and MBP degradation,suggesting demyelinating nerve injury3.N-cadherin was up-regulated in DEACMP rat,and its expression was associated with nerve injury in DEACMP rat.