Effects Of Different Levels Of Controlled Hypotension On A? Protein And Tau Protein Phosphorylation Expression In Hippocampal CA1 Region In Rats

Objective:Using the sodium nitroprusside and esmolol,controlling blood pressure reduction in the different levels in rats,observe the effect of controlling hypotension on postoperative cognitive function in rats,and the change of A? protein and tau protein phosphorylation in hippocampal CA1 region.Method:The experiment was performed in two parts: In part one,we investigate the effects of different levels of controlled hypotension on postoperative cognitive function in rats.In part two,we investigate the effects of different levels of controlled hypotension on change of A? protein and tau protein phosphorylation in hippocampal CA1 region.Niety-six adult male SD rats,weighing 280~320g,were randomly divided into four groups(n=24 each): Control group(group C,without any treatment),controlled hypotension ?group(group CH1,mean arterial pressure fell to 30% of the baseline),controlled hypotension ?group(group CH2,mean arterial pressure fell to 45% of the baseline),and controlled hypotension ? group(group CH3,mean arterial pressure fell to 60% of the baseline).And the target blood pressure was maintained 1h.During the study,monitored the MAP and HR of the rats and observed the blood gas analysises.Cognitive function was assessed by Morris water maze test.The hippocampus was removed for microscopic examination,detection of neuronal apoptosis by TUNEL,and determination of the expression A? protein and tau protein phosphorylation in hippocampal CA1 region by Western blot.Result:(1)Compared with group C,the escape latency was significantly prolonged,and the frequency of crossing the original platform was decreased in group CH2 and CH3(P<0.05),and there was no significant difference in group CH1(P>0.05).Compared with group CH1,the escape latency was significantlyprolonged,and the frequency of crossing the original platform was decreased in group CH2 and CH3(P<0.05).Compared with group CH2,the escape latency was significantly prolonged,and the frequency of crossing the original platform was decreased in group CH3(P<0.05).(2)The hippocampal neurons morphology was not seen abnormal in group C and CH1.The neurons disposed irregularly,cell boundary and array was not very clear in group CH2.The neuronal injury was more serious,and the neurons disposed disorderly and were lost seriously in group CH3.(3)Compared with group C,the expression A? protein and tau protein phosphorylation in hippocampal CA1 region was increased in group CH2 and CH3(P<0.05),and there was no significant difference in group CH1(P>0.05).Compared with group CH1,the expression A? protein and tau protein phosphorylation in hippocampal CA1 region was increased in group CH2 and CH3(P<0.05).Compared with group CH2,the expression A? protein and tau protein phosphorylation in hippocampal CA1 region was increased in group CH3(P<0.05).Conclusion:1.Controlled hypotension can cause postoperative cognitive dysfunction in rats.With the level of controlling blood pressure more lower,the worse of the postoperative cognitive dysfunction.2.The mechanism of controlled hypotension cause postoperative cognitive dysfunction in rats maybe up expression A? protein and tau protein phosphorylation in hippocampal CA1 region.