The aim of this study was to determine the effect of RNA interference inhibition of
mineralocorticoid receptor (MR) on cold-induced
hypertension (CIH) and renal damage. Recombinant adeno-associated virus (AAV) carrying short hairpin small interference (si)
RNA for MR (AAV.MR-
shRNA) was constructed and tested for the ability to inhibit renal MR and to control CIH. Three groups of rats with CIH received AAV.MR-
shRNA (1.25 x 10(9) particles/rat, intravenous), AAV carrying scrambled
shRNA (AAV.Control-
shRNA) (1.25 x 10(9) particles/rat, intravenous) and
phosphate buffer solution (PBS), respectively. All rats were kept in a cold chamber (6.7 degrees C) throughout the experiment. Adeno-associated virus delivery of MR-
shRNA prevented progression of CIH. Blood pressure (BP) of the AAV.MR-
shRNA-treated group did not increase and remained at 145+/-3 mm Hg, whereas BP of the AAV.Control-
shRNA-treated and PBS-treated group increased to 167+/-4 and 161+/-3 mm Hg, respectively, at 3 weeks after gene delivery. Thus, the
antihypertensive effect of a single injection of AAV.MR-
shRNA lasted for at least 3 weeks (length of the study). Adeno-associated virus carrying short hairpin
siRNA for MR significantly increased urinary
sodium excretion and decreased
proteinuria. It also decreased serum
creatinine and blood
urea nitrogen, suggesting enhanced renal function. Both Western blot and immunohistochemical analysis showed that MR expression was decreased significantly in the kidney in the AAV.MR-
shRNA-treated rats, confirming that renal MR is effectively inhibited by AAV.MR-
shRNA. Adeno-associated virus carrying short hairpin
siRNA for MR also significantly attenuated renal
hypertrophy. In addition, AAV delivery of MR-
shRNA prevented
atrophy and dilation of renal tubules and abolished tubular deposition of proteinaceous material seen in CIH rats.
CONCLUSIONS: