AIM:To evaluate the effect of microRNA-155(miRNA-155) on the regulation of angiogenesis in diabetic rats with cerebral ischemic injury .METHODS: Adult male Sprague-Dawley rats were randomly divided into 5 groups:sham group, cerebral ischemia group , diabetic cerebral ischemia group , diabetic cerebral ischemia +miRNA-155 inhibitors group and diabetic cerebral ischemia +scramble group .Diabetes model was made by injection of streptozocin and permanent cerebral ischemic model was developed by suture-occluded method .The scores of neurological deficit and infarct volume were estimated at 24 h after cerebral ischemia .miRNA-155 level was detected by real-time polymerase chain reaction.The expression of platelet endothelial cell adhesion molecule-1 ( PECAM-1/CD31 ) and vascular endothelial growth factor ( VEGF) was detected by Western blotting .RESULTS:miRNA-155 inhibitor significantly reduced miRNA-155 levels in the ischemic cortex (P<0.05), improved the scores of neurological deficit , reduced infarction size and up-regulated the levels of CD31 and VEGF (P<0.05).CONCLUSION:miRNA-155 has a critical role in the regulation of angiogenesis in diabetic rats with cerebral ischemia .Down-regulation of miRNA-155 using miRNA-155 inhibitor attenuates brain infarct injury in diabetic rats .

BACKGROUND: Microglia play an important role in immune surveillance in their quiescent state, but the role of the activated microglia is under discussion. OBJECTIVE: To analyze the mechanism of activated microglia in acute cerebral infarction. METHODS: Totally 96 male Kunming mice were selected and randomly divided into four groups, including transplantation, placebo, blank control and sham operation groups. Permanent occlusion of the middle cerebral artery was performed using suture method in the mice of the transplantation, placebo and blank control groups, followed by injection of microglia suspension via subclavian vein, medium containing the same volume of microglia, and nothing, respectively, at 12 hours after modeling. In the meanwhile, the same amount of microglia suspension was injected into the mice of the sham operation group. The Zea-longa scale and brain-derived neurotrophic factor expression at 12, 24 and 72 hours after modeling, the volume of cerebral infarction and the number of nerve cells positive for microtubule-associated protein-2 at 72 hours after modeling were detected. RESULTS AND CONCLUSION: The Zea-longa scale score was 0 point in the sham operation group, which was significantly lower than that in the other three groups at each time point after modeling (P < 0.01). The Zea-longa scores in the transplantation group were significantly lower than those in the placebo and blank control groups at 24 and 72 hours after transplantation (P < 0.01). The positive expression rate of brain-derived neurotrophic factor in the transplantation group was significantly higher than that in the other three groups after transplantation (P < 0.01). The sham group showed no infarction, while the size of cerebral infarction in the transplantation group was significantly lower than that in the placebo and blank control groups (P < 0.01), and the microtubule-associated protein-2 positive rate was significantly higher than that in the placebo and blank control groups (P < 0.01). These results manifest that the activated microglia can improve the survival rate of nerve cells, promote the recovery of cerebral nerve function and reduce the size of cerebral infarction.