The Effect On The Apoptosis And Expression Of Neuroglobin In The Hippocampus Of The Rat With Sustained Threshold Controlled Hypotension At Different Times

Objective:This research aimed to make clear about the time limit for the continued safety of the threshold(MAP=55mmHg)controlled hypotension and the mechanism of leading to brain injury, with the support of observations of the tolerance of the rat brain after threshold controlled hypotension at different time.Methods:SD rats were randomly divided into 4 groups, each group with 6 rats:Group A(normal);Group C(sustained controlled hypotension), Group C set three different points of sustained controlled hypotension:2h, 4h,6h. So 3 groups:C1, C2, C3. Use sodium nitroprusside (SNP) and esmolol (ESM) induced hypotension, using tracheotomy for mechanical ventilation. During the time of controlling blood pressure, recorded rats' vital signs and did blood gas analysise.24-hour later, observed the rats' neurobehavioral function and survival rate after hypotension, recorded the blood gas analysises again. Evaluated the apoptosis by Tunel and determined the expression of neuroglobin by immunohistochemistry of hippocampus.Result:(1) Assessment of the rats'neurobehavioral function:there were statistic difference (P<0.05) between group C3 and A. The survival rate after 24 hours of group C3 was 60%. Other groups were 100%.(3) A statistic difference of apoptosis-index(AI%) lied in group C2 and A(P<0.05). So was the C3and A. The group C2 group C3 were all had difference between group C1(P<0.05). There was great statistic difference between C3 and C2 (P<0.01).(4) There was statistic difference of neuroglobin immunoteactive (Ngb-IR) numbers between C and A(P<0.05). The Ngb-IR in the group C2 and C3 were more than C1(P<0.05). The statistic difference was also marked between group C2 and C3(P<0.01). Group C2 had the most Ngb-IR number. And the next one is group C3. The highest average optical density(A) lied in group C2(P<0.05), and the second one is C3 (P<0.05).Conclusions:(1) After hypotension of MAP55mmHg continued for 6h induced by SNP and ESM, rats'neurobehavioral function was severely damaged.(2) 4h hypotension of MAP55mmHg induced by SNP and ESM can had a notable changed on the AI% of hippocampus. Hypotension during 6h, the AI% was distinguished different between other groups.(3)Continued induced 4h hypotension of MAP55mmHg can made Ngb-IR a strongly expression. Continued for 6h can only lead Ngb-IR a waek expression. This indicated that the neurons showed an irreversible damage with the step-down time.