H19 expression is upregulated after MCAO injury while H19 inhibition alleviates rat MCAO injury
Given the increased H19 expression in patients with stroke, we further evaluated the role of H19 in cerebral ischemic injury through intravenous injection of H19 siRNA to rats at 3 days before MCAO. Quantitative PCR was performed to detect H19 expression and verify the efficacy of H19 siRNA transfection. First, there were increased H19 levels in the ischemic brain of rats at 24 h after MCAO (Figure 2A,P < 0.001). There were no significant differences in leukocyte H19 levels between MCAO rats and sham rats; however, there was an upregulation trend (Figure 2A, P > 0.05). There was decreased leukocyte H19 expression after treatment with H19 siRNA (Figure 2B, P < 0.001). Furthermore, TTC staining showed that H19 siRNA treatment decreased cerebral infarct volume and oedema volume compared with that in MCAO rats (Figure 2C,P <0.05). Moreover, H19 siRNA alleviated the MCAO-induced neurological deficits (Figure 2C, P <0.05).
To determine whether H19 siRNA preserves neurons from ischemic injury, we examined the number of NeuN/TUNEL-positive cells in rats after MCAO. MCAO injury increased the number of cortical TUNEL-positive cells compared with sham-operated rats, which was abrogated by H19 siRNA treatment (Figure 2D, E P < 0.05). These results demonstrate that H19 inhibition can attenuate cerebral ischemic injury in the cortex.