Neuroprotective Effects Of Baicalin On Neonatal Rats After Hypoxic-ischemic Brain Damage

Objectives:1. To study the effect of baicalin on Fas and FasL experssions in injured braincells of neonatal rats after hypoxic-ischemic brain damage(HIBD).2. To compare neuroprotective effects between baicalin(BC) and nerve growthfactor(NGF) on neonatal rats after hypoxic-ischemic brain damage.Methods:1. Grouping: A total of1287-day-old SD rats were randomly divided into4groups(n=32in each group): sham operated group(Sham group); hypoxic-ischemicbrain damage group(HIBD group); nerve growth factor group(NGF group); baicalingroup(BC group).2. Model building and intervention: Building HIBD model according to themethod of Rice, only identified and dissected the left carotid arteries of the rats inSham group, without ligating and hypoxia exposure. Rats in NGF group and BCgroup were treated correspondently with nerve growth factor injection(50μg kg-1)and baicalin injection(16mg kg-1) after hypoxia-ischemia(HI) injury; while giventhe rats in Sham group and HIBD group with physiological saline(10ml kg-1).3. Observing and testing: To observe the changes of animal behavior after HIduring the experiment, calculate survival rate and7d weight growth. The brain tissuesamples were obtained at four time points of24h、48h、72h、7d after HI(eight rats ateach time point) to test the following indexes: the pathological changes of braintissue were observed by microscope; the expressions of Fas and FasL in injured braincells were detceted by immunohistochemistry methods.Results:1. Changes of animal behavior after HI: During the experiment, no abnormalbehavior was found in the rats of Sham group; While the rats in the other groupsappeared oxygen-deficit symptoms at half a hour after HI, such as skin cyanosis, thenabnormal limb muscle tension, even unconsciousness, etc. When restored ventilation,changes of animal behavior were seen in spontaneous rotation to the ligated side. 2. Survival rate: All rats in Sham group were survival, while five rats died inHIBD group with survival rate84.38%(27/32); Only two rats died in NGF group andthe survival rate was93.75%(30/32) similar with BC group90.63%(29/32), inwhich three rats died. Accounting the difference of survival rates among differentgroups, there were no statistical difference(P>0.05).3. Weight growth: The weight of rats in HIBD group were lightest, whose7dweight growth(14days of age body weight minus7days of age body weight) weresignificantly less than other three groups(P <0.01); Comparing the7d weight growthbetween BC group and NGF group, the results showed no difference(P>0.05), butboth lagged behind the Sham group(P<0.01).4. The pathological of brain tissue: In Sham group, the brain cells were arrangeduniformly and the structure of cells were complete; While in HIBD groups, suchchanges could be observed: brain cells were arranged disorderly and appeared edema,necrotic cells scattered, nuclei were disappeared and vacuolated(changes at48h timepoint were the most significant). Comparison at the same time point: the changes inBC group and NGF group were slighter than HIBD group.5. Expressions of Fas and FasL: There were a l expressions of Fas and FasL inbrain cells in Sham group at each time; In other groups, Fas and FasL positive cellsgradually increased in brain tissue after HI, the peak time of expression was48h afterHI, then expressions decreased gradually and were found until7d after HI, but stillmore than Sham group. There were statistical differences among different time pointin these groups(P<0.01); The expressions of Fas and FasL at different time point inBC group and NGF group were similar at the same time(P>0.05), but theexpressions were less than those in HIBD group(P<0.01).6. The correlation analysis between expressions of Fas and FasL: Fas and FasLpositive expressions at different time point in HIBD group were correlated(r=0.863，P=0.000<0.01).Conclusions:1. Expressions of Fas and FasL increase evidently in brain cells of neonatal ratsHIBD, the peak time of expression is48h after HI, then decrease gradually, and couldbe found until7d after HI, while there are a few expressions of Fas and FasL in brain cells in Sham group.2. Baicalin playes a role of neuroprotection on neonatal rats HIBD by reducingthe expressions of Fas and FasL in injured brain cells.3. Baicalin has similar neuroprotective effects with nerve growth factor onneonatal rats HIBD,which could become a substitute for nerve growth factor in thefuture.