RESUMO
Objective To investigate the effect of targeting vascular endothelial growth factor (VEGF) by microRNA-126 (miR-126) on neuronal damage in neonatal rats with hypoxic-ischemic encephalopathy (HIE). Methods Newborn 7 days old SD male rats were randomly divided into four group, sham operation group (group A), HIE group (group B), HIE+negative control group (group C), and HIE+miR-126 overexpression group (group D), eighteen in each group. After modeling, neurological deficit score and brain water content were measured. HE staining was used to observe the pathological changes of CAI area in hippocampus of brain in each group. Real-time PCR was used to detect the expression of miR-126 and VEGF. Immunohistochemistry was used to detect the expression of VEGF in CAI area in hippocampus of brain. Double luciferase target experiment was used to verify the targeting relationship between miR-126 and VEGF gene. Flow cytometry was used to detect neuron apoptosis in hippocampus. Western blotting was used to detect the expression of cleaved-Caspase-3 protein in brain tissue of rats in each group. Results There was no neurobehavioral damage in group A, the neurobehavioral score was 0, and the brain tissue was not damaged; the neurobehavioral scores in group B and group C were (2. 50±0. 55) and (2. 33±0. 82) respectively, and the brain tissue damage was obvious; the neurobehavioral score in group D was ( 1. 50 ±0. 55), and the damage of brain tissue was improved. Compared with the group A, the neurobehavioral score (P<0. 05) and brain water content of group B and group C increased significantly (P<0. 05); Compared with the group B, the neurobehavioral score (P<0. 05) and brain water content of group D (P<0. 05) decreased. Compared with the group A, the expression level of miR-126, VEGF mRNA and protein, neuron apoptosis rate and cleaved-Caspase-3 in brain tissue of group B and group C were all significantly lower (P<0. 05). Compared with the group B, the expression level of miR-126, VEGF mRNA and protein, neuron apoptosis rate and cleaved-Caspase-3 in hippocampus of group D were all significantly higher (P<0. 05). The result of luciferase reporter gene experiment showed that miR-126 and VEGF could be targetly binded. Conclusion Overexpression of miR-126 can reduce neuronal apoptosis in hippocampus of brain and improve the development of HIE. The mechanism may be related to the targeted inhibition of VEGF gene expression by miR-126.