| Objective:To observe the caspase-3 and Aβ1-42(β-amyloid) expression variation of 7 days rats with hypoxic-ischemic brain damage(HIBD),and to approach the protection of NAP (activity-dependent neuroprotective protein),so as to search for a new possible method to treat newborns with HIBD.Methods:A total of 78 Wistar neonatal rats,cleanliness standard,female or male,with the birth weight of 16 to 20 gram were randomly divided into(1) sham operation group(2) HIBD group(3) NAP treatment group and(4) NAP preconditioning group.The rats in sham operation group were only cut of a nick in the middle of their cervical part,then suture their incisions, these rats' common cervical arteries were not been clamped and they had not undergone HIBD. And the other rats had undergone hypoxic-ischemic brain damage,their right common carotid artery were ligated for 1 hour,then breathed with 8%oxygen and 92%nitrogen mixed gas,the hypoxic-ischemic brain damage model were prepared.The rats of NAP preconditioning group were injected NAP in their abdominal cavities 30 minutes before undergoing HIBD.The rats of NAP treatment group were injected NAP after they were taken out of mionectic box.The rats of the second,third and fourth group were observed after undergoing HIBD at the first day,third day,fifth day and seventh day respectively.There were 6 rats in every time points.The form variation of nerve cells were observed by HE staining under light microscope in different time points,and the caspase-3 and Aβ1-42 expression variation were evaluated by immunityhistochemistry staining of the rats in sham operation group,HIBD group,NAP treatment group and NAP preconditioning group in different time points.Result:The rats of HIBD group,NAP treatment group and NAP preconditioning group behaved disorderly in different extent.It is hard to find caspase-3 and Aβ1-42 positive cell in rats' pallium of sham operation group under light microscope.Caspase-3 and Aβ1-42 positive cells were increased obviously after hypoxic ischemia,which can be found after 1 day of hypoxic-ischemia,and up to the highest on the third day,and lowered afer the seventh day.There were obvious difference between HIBD group and sham operated group of caspase-3 and Aβ1-42 positive cells number(P＜0.05).There were obvious differences among NAP treatment group, NAP precontioning group and HIBD group in terms of caspase-3 and Aβ1-42 positive cells count (P＜0.05).There were not obvious differences between NAP treatment group and NAP preconditioning group in terms of caspase-3 and Aβ1-42 positive cells count(P＞0.05).There were linear positive correlation between caspase-3 and Aβ1-42 of rats with hypoxic-ischemic brain damage(r=0.423).Conclusion:Large dose of NAP for rats undergoing HIBD have no obvious motion improvement.The increased expression of caspase-3 and Aβ1-42 explained that the apoptosis induced and nerve damage by caspase-3 and Aβ1-42 participate the pathomechanism of rats undergoing hypoxic-ischemic brain damage.But NAP can protect nerve system and help the nerve's recovery and regeneration by inhibiting the expression of caspase-3 and Aβ1-42. |
