| Objective: The aim of this study is to establish the model of hypoxic ischemic braindamage (HIBD) in the7-day-old newborn SD rats, detect the serum levels of theubiquitin carboxy-terminal hydrolase L1(UCH-L1) protein at different time points, toexplore (1) the utility of serum UCH-L1in the early diagnosis of hypoxic-ischemicencephalopathy (HIE) in newborn rats, and (2) its relationships with the severity ofbrain injury, and then provide well experimental basis for the early clinical diagnosisand prognosis of neonate with HIE.Methods:(1) One hundred and sixty eighty7-day-old newborn SD rats wererandomly divided into control group, sham-operation group and HIBD model groupwith56rats in each group. HIBD models were established with improved Rice method.According to the time that the animals were sacrificed, all the three groups wererandomly divided into seven subgroups with8rats in each subgroup:6h,12h,24h,48h,72h,96h and7d.(2) The changes of sport behavior of the rats in each group wereobserved before and after the experiment. The modified Neurological Severity Scores(mNSS) test was used to evaluate neurological function.(3) The specimen of blood wasfirstly collected at6h in the HIBD model group. Then all rats were sacrificed by methodof decapitating to collect blood and brain tissue specimens at the same time points. Thevariation in brain morphology and histopathology was examined by H&E StainingMethod.(4) The serum levels of UCH-L1protein was detected by double-antibodysandwich ELISA.Results:(1) Observations on the changes of sport behavior: All the rats in the controlgroup and sham operation group were with normal movement, reflexes, sensation andbalance. But the rats in the HIBD model group developed gradually the symptoms ofhypoxic-ischemic brain injury.(2) Modified Neurological Severity Score (mNSS) scoreof rats: The mNSS score in the control group and sham operation group was0(withoutinjury), and in the HIBD model group was as follow:4.78±1.39(17rats with mildinjury,),9.36±1.92（25rats with moderate injury） and14.63±1.41（14rats with severeinjury）.(3) The macro morphology of brain by the naked eye: the brain tissue was ofnormal appearance in the healthy control group and sham operation group, but varying degrees of edema and liquefactive necrosis was found in the HIBD model group.(4)The micro morphology of brain by HE staining: in the healthy control group and shamoperation group: the neuronal cells were normal; in the HIBD model group: edema,degeneration, necrosis and apoptosis were observed in the neuronal cells at differenttime points, combined with the hyperplasia of glial cells.(5) The difference in serumlevel of UCH-L1protein at different time points: There was no significant difference inthe levels of UCH-L1protein among each subgroup in the control group and shamoperation group (P>0.05); The difference in UCH-L1at different time points betweenthe control group and sham operation group was also not significant (P>0.05), revealedthat the expression of UCH-L1protein may not be influenced by surgical factors in thesham operation group; The difference in the serum levels of UCH-L1at different timepoints was statistically significant between the HIBD group and the control group orsham operation group (P<0.05). There was no significant difference between in theserum level of UCH-L1protein between the control group and sham group (P>0.05);the difference in the levels of UCH-L1protein was significant between the HIBD modelgroup and the control group or sham group (P<0.05); There was significant difference inthe serum level of UCH-L1protein among the subgroups in the HIBD model group(P<0.05). The levels of serum UCH-L1protein began to increase at6h after theoperations, reach the peak level at48h, and then decreased gradually.(6) The serumlevels of UCH-L1protein and different mNSS score rats analysis in the HIBD modelgroup: the serum levels of UCH-L1protein in the severe injury rats were higher thanthose in the moderate injury rats, and conceivable higher than those in the mild injuryrats, the difference among the them was statistical significant (P<0.05); The serumlevels of UCH-L1protein associated with mNSS score.Conclusions:(1) The model of HIBD in the7-day-old newborn SD rats wassuccessfully established.(2) UCH-L1protein can be used as a novel biochemicalindicator for the early diagnosis (6h) of HIE in neonatal rats.(3) The levels of serumUCH-L1protein began to increase at6h after the operations, reach the peak level at48h,and then decreased gradually.(4) The serum level of UCH-L1was positive correlated tothe severity of brain damage in neonatal rats with HIE, and can be used to assess theseverity of brain damage. |
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