| Objective: Neonatal Hypoxic-Ischemic Brain Damage (HIBD) caused in most cases by perinatalasphyxia. It appeared a series of clinical encephalopathy and was one of the important causes inchildren with disability in China. This experiment set up neonatal rat hypoxic-ischemic braindamage (HIBD) model, to observe the expression of HIF-1αof brain tissue after neonatal ratswith HIBD and possible protection mechanisms of deferoxamine (DFO). Our experiment mayprovide theoretical basis for clinical application of DFO in newborns with HIE.Methods: A total of 120 seven-day-old Wistar rats were randomly divided into three groups:sham-operated group (n=8), hypoxic-ischemic brain damage (HIBD) group and DFO group.HIBD group and DFO group were first prepared by HIBD model. Rats of each group werefurther divided into seven sub-groups (n=8 in each subgroup) based on different time points afterHIBD (3h, 6h, 12h, 24h, 48h,72h, 7d) respectively. HIBD model rats were prepared by keepingrats into hypoxic environment of 8% O2concentration for 2 hours after clamping left commoncarotid artery. Rats in deferoxamine group were given deferoxamine (200mg/kg, intraperitonealinjection) before 24h HIBD. Sham-operated group rats were given median neck incision andfreed left common carotid artery, non hypoxic-ischemic. Rats were sacrificed at different timepoints, to observe morphological changes in brain tissue in general. Pathological changes of leftbrain tissue of all subjects were observed under light microscope. And immunohistochemicaltechnique was used to determine the expression of HIF-1αand Caspase-3.Results: (1) Neonatal rats had various abnormal behaviors after HIBD. (2) After HIBD, variousmorphologic abnormalities of brain tissue at different time points have been observed.Above-mentioned changes weakened after deferoxamine intervention.(3) HE staining: Insham-operated group, brain tissue had normal size and morphology, brain tissue structure andcell-level clearly, neurons were in order closely; Different extent cellular swelling of neurons,degeneration, necrosis, cellular nuclear fragmentation, solution, neuron loss, gliocyteproliferation were observed in brain tissue of HIBD model groups at different time points. InDFO group, pathological changes of brain tissue lessened significantly than HIBD model groups,more nerve cells were survived, and cells were in order, Only a small amount of nerve cellsdegeneration and necrosis have been observed. (4) Immunohistochemical staining: Expressionsof Caspase-3 and HIF-1α: Caspase-3 and HIF-1αpositive staining showed buffy fine graindeposition, positive cells were found in cerebral cortex and hippocampus, and positive staining was mainly in cytoplasm and axon process of nerve cells.①Expressions of HIF-1α:HIF-1αprotein in sham-operated group showed a low level of expression, there were nosignificant differences among at different times; HIF-1αpositive cells were observed in braintissue in HIBD group at each time point, and the expression of HIF-1αpositive cells wasincreased significantly than sham-operated at the same time point. There was statisticalsignificant difference between them (P<0.05). in HIBD group HIF-1αprotein expression wasincreaseded at 3h，and was peaked at 12h,then gradually reduced, However, in DFO group HIF-1αprotein expression was peaked at 6h，maintained higher level at 12h and 24h，HIF-1αproteinexpression was much higher than hypoxia ischemia group at each time point, the differenceswere statistically significant (P<0.05).②Expressions of Caspase-3: Caspase-3 protein insham-operated group showed a low level of expression, no significant change at different time.The expression of Caspase3 protein was significantly increased at 6h, the higher levels weremaintained at 12h and 24h，and then 7d began to decline, It is still maintaining a certain level, Itwas much higher than sham group at each time point ,with the sham group compared to thedifferences were statistically significant (P<0.05); The expression of CC3 protein slightlyincreased at 3h in DFO group，It was significantly increased at 12h, the higher levels weremaintained at 24h and 48h, and then 7d began to decline ,Caspase3 protein expression was muchlower than hypoxia ischemia group at each time point ,with hypoxia ischemia group compared tothe differences were statistically significant (P<0.05). TUNEL positive cells (AI index)expression is mainly distributed in the cortex and hippocampus. Sham-operated group TUNELpositive cells with minimal, HIBD group TUNEL positive cells increased than the control group,and with time gradually increased; there was significant difference between two groups (P <0.05). Group DFO TUNEL positive cells decreased than in HIBD group, there was significantdifference between two groups (P< 0.05).Conclusion: (1) Given deferoxamine before HIBD in neonatal rats can reduce pathologicalchanges of brain tissue, which suggests that deferoxamine has neuroprotective effect. (2)Deferoxamine could upregulate the expression of HIF-1αand downregulate the expression ofCaspase-3, alleviate pathological process of HIBD. It may inhibit neuronal apoptosis and providea protective effect for hypoxia-ischemia-induced cellular injury of neurons of neonatal rats.Further provided new treatment method for the clinical treatment of neonatal hypoxic ischemicbrain injury. |
PDF Full Text Request