| Objective: Germinal matrix-intraventricular hemorrhage(GM-IVH)is one of the most common forms of brain injury in premature infants,and neonatal intracranial hemorrhage above 80% is GM-IVH.The incidence rate of GM-IVH is 20%~25% in very low birth weight infants,and it increases to45% in the premature infants with body weight of 500~750g.Studies have shown that the smaller gestational age and the lower body weight,the higher incidence rate of GM-IVH.With the improvement of perinatology and the development of neonatal intensive care technology,the birth rate of preterm infants,super preterm infants and very low birth weight infants is getting higher and higher and coming with the increase of the incidence rate of GM-IVH in preterm infants.GM-IVH occurres more in preterm infants with gestational age less than 34 weeks,and the GM-IVH surviving pretem infants were found different degrees of neurological dysfunction,cerebral palsy,cognitive disorders,behavioral defects,etc.during the follow-up,so it not only influences the life quality of pretem infants seriously and also bring heavy burden to the family and society.Therefore,GM-IVH and the sequelae it caused are still very important problem to be solved.The central nervous system of premature infants is immature,brain injury mechanism is complex,one of the pathogenesis of brain injury is a large number of excitatory amino acid secretion caused by excitotoxicity.Glutamic acid is a common excitatory amino acid that plays a role in binding to its receptor,alpha-methyl-3-hydroxy-5-methyl-4-isoxazolyl propionic acid(AMPA),one of the ionic receptors,widely distributed in glial cells and neurons in the hippocampus,cerebral cortex,striatum and cerebellum.After the brain injury,activation of AMPA receptor,glutamate binding inoligodendrocytes and neuronal surface of the AMPA receptor,induced calcium overload,resulting in neuronal cytoskeleton protein degradation,destruction,causing neuronal damage.Acting on the oligodendrocyte membrane surface AMPA receptor,resulting in oligodendrocyte damage,myelination.2,3-dihydroxy-6-nitro-sulfonamide-quinoxaline(NBQX)is an inhibitor of AMPA receptors for use in GM-IVH patients by inhibiting neuronal and oligodendrocyte surface AMPA Receptor expression,whether to reduce neuronal damage,protect oligodendrocytes,the current domestic research has not been reported.In this study,GM-IVH rabbit model was used to investigate the expression of myelin basic protein(MBP)in GM-IVH and to detect the injury of myelin.To investigate the neuronal injury in GM-IVH rabbits by detecting the expression of microtubule associated protein-2(MAP-2).GM-IVH can increase the demyelination of GM-IVH after NBQX,and play a protective role in neurons.Methods:1 Selecte pregnant rabbits with 29 days pregnancy(full-term pregnancy of 32 days)from New Zealand,quickly remove the preterm rabbits by cesarean section.Warm and feed the young rabbits after birth quikly.Intraperitoneally inject part of the premature rabbits with 50% glycerol,dosage of 10mL/Kg,and the others do not recieve any treatment.2 Observe the GM-IVH development by cranial untrasound 24 later after birth.3 GM-IVH premature rabbits would be randomly divided into two groups,NBQX treatment group(15),and model group(15).And then take 15 pups without any treatment after birth as normal group.NBQX treatment group would be given anterior fontanel injection with NBQX,dosage of 10?g/kg·d.While given the same volume of saline to model group.Within each group,preterm rabbits were randomly divided into three sub-groups(3 days,7 days and 14 days after GM-IVH),all the preterm rabbits were given euthanasia and then the peri-ventricular zone tissues would be quickly separated on ice.Partsof the peri-ventricular zone tissues would be immersed in 4%paraformaldehyde solution,for the immunohistochemical experiment.The rest would be put in-80? refrigerator,used of western blot.4 Compare the expression of microtubule-associated protein-2(MAP-2)in the periventricular zone of the NBQX treatment group,the model group and the normal group by immunohistochemical method.5 Detact the expression of myelin basic protein(MBP)in the periventricular zone of the NBQX treatment group,model group and normal group by western blot method.6 Statistical analysis SPSS19.0 statistics software and Microsoft Excel2003 were used to carry on statistics processing.Measurement data was performed with mean±standard deviation.If the data are homogeneity of variance,the comparison between or among groups were performed with LSD.If they do not meet the homogeneity of variance,use rank sum.P-value <0.05(double side)had statistical significance.Results:1 Sucessfully copied the model of preterm rabbit with GM-IVH.Selected pregnant 29 days of New Zealand pregnant rabbits for cesarean section,quickly remove the preterm rabbits.The specimen showed the intra-ventricular hemorrhage in preterm rabbits.2 The expression of MBP in the brain.The expression of MBP in brain tissue of normal group was increased at3 days,7 days and 14 days after birth,and there was no significant compared3 day with 7 day(P>0.05);the expression of MBP at 14 days was higher than 3days and 7days,and the difference was significantly(P<0.05).The expression of MBP in the model group was lower than that in the normal group at 3 days,7 days and 14 days,the difference was significantly(P<0.05)In the NBQX group,the expression of MBP increased gradually at 3 day,7 day and 14 day,and there was no significant difference between the 3 day and the 7 day(P>0.05).3 day and 14 day,7 day and 14 day difference wassignificantly(P < 0.05).At 7 day and 14 day,the difference of MBP expression between NBQX treatment group and model group was significantly(P<0.05).3 The expression of MAP-2 in the brain.MAP-2 in the normal group of brain tissue arranged neatly,fibrous,uniform staining.the expression of MAP-2 were gradually increased after born at 3 day,7 day,14 day,all had difference(P<0.05).The MAP-2arrangement in the brain tissue of the model group at 3 day was irregular and sparse,and the staining was significantly lighter in the control group,at 14 days the expression gradually increased,MAP-2 arrangement is relative completely,the staining is still light,but the expression was stronger than before,the expression of MAP-2 was statistically significant at any two time points in the model group.the expression level lower than the normal group,the difference was significant(P<0.05).The expression of MAP-2 in brain tissue of NBQX treatment group was increased at 3 days,7 days and 14 days after birth,all had difference(P<0.05).At 7 days and 14 days,the expression of MAP-2 level of the model group was higher than that of the model group at the same time point,lower than that of the normal group,all had difference(P<0.05).Conclusions:1 The expression of MBP and MAP-2 in brain tissue was decreased after GM-IVH in premature rabbits.2 After the treatment of NBQX,to a certain extent the expression of MBP and MAP-2 can be increased. |
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