| Objective:This experiment has set up the hyperbilirubinemia newborn rat model,after the intervention of nerve growth factor,observed the relationship between Caspase-3expression and apoptosis in brain tissue of rats,to investigate the influence of nerve growth factor on brain injury and its possible mechanism and provide the experimental basis for the clinical application of NGF in the prevention and treatment of bilirubin encephalopathy.Methods:A total of 72 7-day-old SD(Sprague-Dawley) rats were randomly divided into hyperbilirubinemia model group(group A,n = 24),hyperbilirubinemia +NGF intervention group(group B,n = 24) and normal control group(Group C,n = 24).According to the different time points,each group was divided into 3 subgroups,24 h group,48 h group and72 h group(n=8).The rats in group A and group B were injected intraperitoneally bilirubin as 100μg/g,only 1 times;The rats in group C were injected intraperitoneally with normal saline as 100μg/g,only 1 times;after set up the model,the rats in group B were injected intraperitoneally NGF immediately,the dose was 50μg/KG/d,which need to be conducted three consecutive days.At last,the brain tissue of rats in each group were taken at different time points.The pathological changes of nerve cells was observed by using HE staining method,the expression of Caspase-3 protein was determined by using immunohistochemistry staining method,the apoptotic index was determined by using Tunel method.Then record the experimental results,calculate the relevant data,cunduct statistical analysis and draw a conclusion.Results:(1)Observe the behavior of rats: after set up the model,significant neurobehavioral abnormalities were found in the rats of group A and group B, after the intervention of NGF, compared with group A, at each time point,abnormal behavior of rats in group B were obviously improved.Rats in control group showed no abnormal behavior.(2) HE After set up the model 24 h,different degrees of edema and degeneration appeared in the brain tissue of the rats in group A and group B;After set up the model 48 h,nerve cell necrosis occurred in the rat brain;After set up the model 72 h,neurons necrosis,glial cells proliferation,nuclear shrinkage and fragmentation occurred in the lesion center;Compared with A group,the injury degree of B group was significantly reduced;Rat neural cell structure in C group was basically normal.(3)Expressions of Caspase-3: The expression of Caspase-3 in hyperbilirubinemia group were higher than that in control group, and it was positively correlated with the time, the difference was statistically significant(P <0.05);The expression of Caspase-3 in NGF group were lower than that in hyperbilirubinemia group, but it were higher than that in control group,the difference was statistically significant(P < 0.05).The expression of Caspase-3 in the control group was very little or no expression, and comparison within group at different time points,there was no statistically significant difference(P>0.05);(4)Apoptosis index: the apoptosis index in hyperbilirubinemia group were higher than that in control group, and it was positively correlated with the time, the difference was statistically significant(P < 0.05);The apoptosis index in NGF group were lower than that in hyperbilirubinemia group, but it were higher than that in control group,the difference was statistically significant(P <0.05).Few cell apoptosis in control group,comparison within group at different time points,there was no statistically significant difference(P>0.05).Conclusion:(1)After the intervention of NGF,at different time points, the pathological changes of brain tissue, such as deformation, necrosis and swelling can be reduced to varying degrees, from the point of view of Pathology,It was confirmed that NGF could reduce the CNS damage caused by excess bilirubin;(2)When the occurrence of hyperbilirubinemia, Caspase-3expression of brain tissues was increased,It mediates bilirubin neurotoxicity, resulting in nerve cell apoptosis;NGF can reduce the expression of Caspase-3 to reduce the damage of bilirubin on CNS. |
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