| Objective : To investigate the effect and mechanism of remote ischemic postconditioning combined with dexmedetomidine on postoperative cognitive function in aged rats with cerebral ischemia/reperfusion.Methods:Sixty healthy male aged SD rats, eighteen to twenty-two months, weighing 280 ~ 320 gram, were randomly divided into 5 groups(n = 12): sham operation group(S group), cerebral ischemia and reperfusion group(I/R group), dexmedetomidine group(D group), remote ischemic post treatment group(R group) and remote ischemic post treatment combined with dexmedetomidine group(R/D group). Rats focal cerebral ischemia/reperfusion injury model was preparated by suture method. Rats were intravenous 3ug/kg dexmedetomidine immediately before ischemia in D group, followed by infusion 3ug/(kg·h) dexmedetomidine for 2h. In R group, the right femoral artery were separated and blocked for 5 min, then recovery for 5min, three ischemia/reperfusion cycles. In R/D group, rats were administered with dexmedetomidine, and the right femoral artery were separated and blocked for 5 min, then recovery for 5min, three ischemia/reperfusion cycles. The ischemia/ reperfusion cycle was proceeded in the two groups. The same volume physical saline was administered before reperfusion in S group, I/R group and R group. Nerve dysfunction score(NDS) was measured at reperfusion 24 h. Respectively after reperfusion 12 h, 24 h, 48 h and 144 h, blood samples were collected for detecting the serum S100 B protein and neuron specific enolase(NSE) concentration. Two rats in each group were randomly selected for executing at reperfusion 24 h, 48 h, 144 h. Acquiring their cerebral tissues, and the content of TNF-? were measured by radioimmunoassay(RIA), the ICAM-1 expression was dected by western blot. The other rats were accepted with Morris water maze test, spatial learning, memory and other cognitive ability test.Results :(1) Compared with S group, NDS, serum S100 B and NSE concentration increased significantly in I/R group(P<0.05); compared with I/R group, NDS, serum S100 B and NSE concentrations were significantly decreased in D group, R group and R/D group(P<0.05). Compared with D group and R group, NDS,serum S100 B and NSE concentrations were further decreased in R/D group(P<0.05).(2) Compared with I/R group, rats escape latent period was significantly shorter from first to fifth day in R group, D group and R/D group(P<0.05). Compared with D group and R group, rats escape latent period was significantly shorter from second to fifth day in R/D group(P<0.05). The number of cross platform in R/D group(7.6 ±1.7) was more than in the R group(5.3±1.5) and D group(4.9±0.9) times(P<0.05).(3) At 24 h, 48 h, 144 h after reperfusion, the expression levels of rats brain tissue TNF-? and ICAM- 1 in each group have significant differencetis. Compared with S group, at 24 h, 48 h, 144 h after reperfusion, brain tissue TNF-? and ICAM- 1 expression levels were up-regulated in I/R group, R group, D group and R/D group. Compared with I/R group, the expression levels of brain tissue TNF-? and ICAM- 1 were down-regulated in R group, D group, R/D group; compared with R group, D group, the expression level of brain tissue TNF-? and ICAM- 1 in R/D group were further decreased.Conclusion :(1)Remote ischemic postconditioning combined with dexmedetomidine could restrain the up-regulation of the serum S100 B and NSE concentrations after aging rat ischemia/reperfusion, and reduce cytokines TNF-? and ICAM-1 expression levels, thereby protect postoperative cognitive function in elderly rats.(2) Remote ischemic postconditioning combined with dexmedetomidine has greater protective effect than a single approach on rat focal cerebral ischemia injury, and the effect of their combined use was better, the neural protective effect was considerably enhanced. |
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