ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of RNA interference (RNAi) targeting angiotensin-converting enzyme (ACE) on the blood pressure and myocardial remodeling in spontaneously hypertensive rats (SHRs).</p><p><b>METHODS</b>Saline (control), adenovirus (Ad5) and recombinant adenoviral vectors (Ad5-ACE-shRNA expressing ACE gene-specific shRN) were randomly administered by caudal intravasation to SHRs (n = 12 each group) at day 1 and day 16. Normotensive Wistar-Kyoto rats (WKY) served as normal controls. Systolic blood pressure (SBP) of the caudal artery was measured daily. Expressions of ACE at mRNA and protein levels in myocardium and aorta were evaluated by RT-PCR and Western blot respectively, ACE serum concentration was measured by ELISA at day 3 (n = 6 each group). The ratio of left ventricular to body weight (LVW/BW), myocardial collagen content were measured and myocardial ultrastructure observed under transmission electron microscope at the study end.</p><p><b>RESULTS</b>Ad5-ACE-shRNA injection significantly reduced SBP (-22 mm Hg, 1 mm Hg = 0.133 kPa) and the antihypertensive effect could last at least 14 days post each injection. SBP was not affected by saline and Ad5 injections. ACE expressions at mRNA and protein levels at myocardium and aorta as well as serum ACE were significantly decreased in Ad5-ACE-shRNA treated SHRs compared to that in saline and Ad5 groups (all P < 0.05) and was comparable to that in WKY group (P > 0.05). The LVW/BW ratio (2.24 +/- 0.19) and myocardial collagen content [(1.283 +/- 0.019) microg/mg] in Ad5-ACE-shRNA treated SHRs were also significantly lower than those in saline treated [3.21 +/- 0.13 and (1.686 +/- 0.013) microg/mg, both P < 0.05] and Ad5 treated SHRs [3.13 +/- 0.12, (1.682 +/- 0.009) microg/mg, both P < 0.05] but still higher than those of WKY group [2.06 +/- 0.11, (1.257 +/- 0.019) microg/mg, both P < 0.05]. Myocardial ultrastructure was also significantly improved in Ad5-ACE-shRNA treated SHRs compared to saline and Ad5 treated SHRs.</p><p><b>CONCLUSION</b>RNAi targeting ACE gene significantly inhibited the expressions of ACE at mRNA and protein levels and resulted in prolonged antihypertensive effects and myocardial ultrastructure improvements in this SHR model.</p>
Subject(s)
Animals , Male , Rats , Blood Pressure , Disease Models, Animal , Heart Rate , Hypertension , Genetics , Peptidyl-Dipeptidase A , Genetics , Metabolism , RNA Interference , RNA, Messenger , Genetics , Rats, Inbred SHR , Rats, Inbred WKY , Ventricular RemodelingABSTRACT
Background Hypertension is a multigenetic inheritable disease.Gene therapy with long-term effects and less side effects by regulating gene expression has been shown to be a potential and exciting prospect. Objective To investigate the effects of RNA interference(RNAi)targeting angiotensin-converting enzyme(ACE)on the blood pressure and ACE expression in kidney of spontaneously hypertensive rats(SHR).Methods SHR were randomly to receive placebo(n=12)or control adenovirus Ad5-EGFP)or a single injection of recombinant adenovi- ral vectors,Ad5-EGFP-ACE-shRNA(n=12,iv).Normotensive Wistar-Kyoto rats(WKY)were served as normal control group.SBP was measured before and after the intervention.Aorta,lung,myocardium and kidney were studied using fluorescence microscope to identify the sites of Ad5-EGFP-ACE-shRNA.Expressions of ACE mRNA and protein in kidney were evaluated by RT-PCR and Western blot.Results SBP of the treat group was effectively reduced by 19.0?3.2 mmHg at the 3rd day,and 22.1?3.3 mmHg at the 13th day of the experiment.The anti- hypertensive effect significant remained at least for 14 days.On the contrary,increase in BP was shown in placebo and the adenovirus control group.Compared with placebo or adenovirus control rats,ACE mRNA expression level in kidney of the treated rats was lower by 61.1% and 62.3% respectively,with ACE protein expression level lower- ing by 56.2% and 53.30% as well(ail P0.05). Conclusion RNA interference targeting ACE gene inhibits the expressions of ACE mRNA and protein.A single dose injection resulted in a prolonged decrease in BP.The evidence of strong antihypertensive effect by genetic therapy justifies efforts for further investigation.