Establishment And Evaluation Of Hyperbilirubinemia And Bilirubin Encephalopathy In Newborn Rats

Objective:It was to etablish a reliable,simple and good simulation model of hyperbilirubinemia and bilirubin encephalopathy in 7 day old SD rats,in order to provide model to explore the pathogenesis and prevent complications in clinical practice.Methods:A total of 50 SD(Sprague-Dawley,SD)rats of 7 day old were randomly divided into 5groups.It was given saline,50mg/kg,100mg/kg,150mg/kg,200mg/kg bilirubin through intraperitoneal injection.After 24 h intervention,obtained the rat brain and heart blood,measured the serum bilirubin level and S-100? in serum and brain,observed nerve cell changes by HE staining,obtained the number of neuronal apoptosis by TUNEL method and calculated the apoptosis rate(Apoptotic,index,AI).It was to record and calculate the experimental results in each team and carried statistical analysis,draw the conclusion,in order to evaluate the reliability and stability of the neonatal rats model.Results:(1)Observed the general situation of the experimental animals: Before the experiment,the rats had good condition in each group,the skin color was red,skin elasticity was well,the response to external stimuli was quick and there was normal behavior.After 24 hours of intraperitoneal injection of bilirubin: The skin of rats in saline group was same with ruddy color and there was normal behavior;The skin of rats in 50mg/kg group was less rosy and the response to external stimuli was slow;The skin of rats in 100mg/kg group and 150mg/kg group was yellow,skin elasticity was poor,the response to external stimuli was slower and there were rolling and fell caused by decreased muscular tension;The skin of rats in 200 mg/kg group was green yellow,skin elasticity was worse and without response to external stimuli or even coma.(2)HE staining: The nerve cells of hippocampus in saline group arranged neatly,complete structure,normal morphology;The nerve cells in 50mg/kg group showed mild swelling and degeneration;The nerve cells in 100mg/kg group and 150mg/kg group showed structure disorder,cell obvious swelling and deformation,some of the nuclear chromatin were dense and concentrated,the cytoplasm were capitation;The nerve cells in200mg/kg group were serious swelling and deformation,most of the nuclear chromatin were dense and concentrated,the cytoplasm were capitation.(3)The level of bilirubin and S-100? in serum and brain tissue: There were statistical difference between the saline group and the other groups in the level of bilirubin and S-100? of serum and brain tissue of rats(P < 0.05);There were no statistical difference between 50mg/kg group and 100mg/kg group in the level of S-100? of serum and brain tissue(P > 0.05).(4)The apoptosis index(AI)measured by TUNEL method: There were statistical difference between saline group and the other groups in apoptosis index(P < 0.05);There were no statistical difference between 150mg/kg group and 200mg/kg group in apoptosis index(P > 0.05).Conclusion:(1)Animal model of hyperbilirubinemia was established through intraperitoneally injection with 50 mg/kg bilirubin in 7d SD rats.(2)Stable bilirubin encephalopathy model was established through intraperitoneally injection with 100mg/kg and 150 mg/kg bilirubin in 7d SD rats.(3)When 150 mg/kg bilirubin through intraperitoneally injection,the glial cell breaks down markedly,So the model of glial cell injury index was established using 150 mg/kgbilirubin in 7d SD rats.