OBJECTIVETo investigate the role of miRNA-210 in hypoxic-ischemic brain edema in neonatal rats.

METHODSA total of 80 neonatal rats were randomly divided into control group, normal saline group, miRNA-210 expression inhibition group, and miRNA-210 overexpression group, with 20 rats in each group. Each group was randomly divided into sham-operation group and hypoxia-ischemia (HI) group, with 10 rats in each group. The neonatal rats in the HI group were treated with ligation of the left common carotid artery and then put in a hypoxia cabin with mixed gas of 8% O2 and 92% N2 for 2 hours; those in the sham-operation group were treated with isolation of the left common carotid artery only, without ligation or hypoxia treatment. After HI or sham-operation, the rats in the normal saline group, miRNA-210 expression inhibition group, and miRNA-210 overexpression group were intracranially injected with normal saline (2.5 mg/kg), miRNA-210 inhibitor (2.5 mg/kg), and miRNA-210 mimic (2.5 mg/kg) respectively. No treatment was given to the rats in the control group. The rats were sacrificed three days later, and the left brain tissue was harvested. Fluorescent quantitative PCR was used to measure the expression of miRNA-210; the dry-wet weight method was used to measure the water content of brain tissue; hematoxylin and eosin staining was used to observe the histomorphological changes in the brain.

RESULTSThe HI groups showed significant reductions in the expression of miRNA-210 and significant increases in the water content of brain tissue compared with the corresponding sham-operation groups (P<0.05). Compared with the normal saline HI group, the miRNA-210 expression inhibition HI group showed a significant reduction in the expression of miRNA-210 and a significant increase in the water content of brain tissue (P<0.05), and the miRNA-210 overexpression HI group showed a significant increase in the expression of miRNA-210 and a significant reduction in the water content of brain tissue (P<0.05). The results of hematoxylin and eosin staining suggested that the miRNA-210 expression inhibition HI group showed marked edema, and the miRNA-210 overexpression HI group showed a significant improvement in edema.

CONCLUSIONSNeonatal rats show down-regulated expression of miRNA-210 after HI, suggesting that miRNA-210 may be involved in the development and progression of hypoxic-ischemic brain edema in neonatal rats.