褪黑素对局灶性脑缺血大鼠扩散加权成像及脑组织中Fas, FasL,活性Caspase-3蛋白表达的影响

Objective Based on middle cerebral artery occlusion (MCAO) model, to investigate the effects of melatonin (MT) on DWI and expression of Fas, FasL and cleaved Caspase-3 proteins in rat model with focal cerebral ischemia. Methods Eighty SD rats were randomly divided into Sham group (n=16), MCAO group (n=32) and MT group (n=32). The rats in sham group were treated with sham-operation. And the rats in MCAO and MT groups were peritoneally injected with saline and MT respectively. The behavioral scores were assessed in the three groups. The rats in MCAO and MT group with the behavioral scores of 1-3 points were selected in the study. The DWI relative signal intensity (rDWI-SI), Fas, FasL and cleaved Caspase-3 proteins were respectively examined by MR scaning and immunohistochemical staining in all rats of each group at 6 h, 24 h, 72 h and 7 days after ischemia reperfusion (IR) or sham-operation. And the DWI and immunohistochemical results for each group were compared. Results At last, there were 16 rats in sham group, 29 rats in MCAO group and 30 rats in MT group, respectively. There was significant difference of the behavioral scores among the three groups (χ²=50.125, P<0.01). The behavioral scores of MT and MCAO groups were higher than those of sham group (all P <0.05). And the behavior scores of the MT group were lower compared with MCAO group after IR. Compared with the rDWI-SI values measured at 6 h, 24 h and 72 h, 7 days in sham group, the rDWI-SI values of MT and MCAO groups were significantly higher (all P<0.01). And the rDWI-SI was higher in MCAO group than those in MT group at 6 h, 24 h and 72 h after IR (all P<0.01). And there was no significant difference of rDWI-SI at 7 days after IR between MT and MCAO groups (P>0.05). The immunohistochemical staining results showed that the number of Fas, FasL and cleaved Caspase-3 positive cells in MCAO and MT groups were significantly higher than those in sham group (all P<0.01). And there were less Fas, FasL and cleaved Caspase-3 positive cells in MT groups compared with MCAO group (all P<0.05) at 6 h, 24 h and 72 h after IR. There was no significant difference of Fas, FasL and cleaved Caspase-3 positive cells among the three groups at 7 days after IR (P>0.05). Conclusion MT can effectively alleviate the rDWI-SI value and inhibit the expression of Fas, FasL and cleaved Caspase-3 proteins in rats of focal cerebral ischemia.