Objectives To investigate the effects of miR-31 on blood pressure and left ventricular remodelling in spontaneously hypertensive rats (SHRs).
Methods Lentiviral vectors carrying miR-31 inhibition gene (LV-miR-31- inhibition) and negative control were constructed. 17-week-old SHRs were randomly divided into 3 groups: LV-miR-31-inhibition treatment (n = 5), negative control (n = 3), and black group (n = 3). The treatment group was injected with 150ul virus solution of LV-miR-31-inhibition with a titer of 1x108 TU/ml via the tail vein. The control and blank groups were injected with an equal volume of negative control virus and enhanced infection solution (ENi. S.) respectively. Throughout the 3-week feeding period, the systolic blood pressure was measured by tail cuff, and the structure and function indexes of left ventricular were observed by high frequency echocardiography (HFUS) for each group animals. After 3 weeks all animals were sacrificed and heat tissue removed and calculated the left ventricular mass index (LVMI). The heart damage was examined by HE staining.
Results LV-miR-31-inhibition caused a significant decrease of blood pressure at 3 weeks (207.22 ± 5.56 vs 175.09 ± 11.89), and the HFUS indexes IVSTd, LVPWd, LVEDD, LVESD was improved dramatically (2.25 ± 0.10 vs 1.75 ± 0.10, 2.28 ± 0.07 vs 1.81 ± 0.07, 4.31 ± 0.11 vs 5.30 ± 0.10, 2.06 ± 0.08 vs 2.63 ± 0.08). The blood pressure was lower in treatment group compared with that of negative control at 3 weeks (208.22 ± 2.86 vs 175.09 ± 11.89), and the HFUS indexes IVSTd, LVPWd LVEDD, LVESD showed a significant difference (2.28 ± 0.04 vs 1.75 ± 0.10, 2.33 ± 0.05 vs 1.81 ± 0.07, 4.28 ± 0.11 vs 5.30 ± 0.10, 2.06 ± 0.05 vs 2.63 ± 0.08). The LVMI of the two groups showed no difference, however the HE staining indicated that the left ventricular hypertrophy was reversed significantly after treatment. Treatments caused no significant changes in negative control and blank control group, and no detectable difference was observed in the two control groups.
Conclusions Down-regulation of miRNA-31 decreases blood pressure and effectively reverses left ventricular remodelling in SHRs.