Long-Term Inhibition of the Central α2B-Adrenergic Receptor Gene Via Recombinant AAV-Delivered Antisense in Hypertensive Rats

Background Salt-induced hypertension is mediated via the α2B-adrenergic receptor (AR) subtype. In α2B-AR gene knockout mice, blood pressure (BP) does not rise with salt loading, and in rats with salt-induced hypertension, BP decreases transiently with antisense (AS) treatment targeting the α2B-AR gene. The present experiments were designed to explore the possibility of gene transfection in the brain by intracerebroventricular (ICV) delivery of AS-DNA via adeno-associated virus (AAV) to prolong α2B-AR inhibition and hence reversal of salt-dependent hypertension. Methods A recombinant AAV (rAAV) vector preparation encoding the α2B-AS fragment (previously tested in vitro for inhibition of α2B-AR protein production in cells) and containing green fluorescence protein (GFP) for visualization was injected ICV into subtotally nephrectomized, salt-fed rats. Control rats received rAAV-GFP (n = 8 per group). Results We observed that BP rose from a baseline of 120 ± 10 to 184 ± 12 mm Hg. Injection of rAAV-α2B-AS produced a 35 ± 12 mm Hg fall in BP, lasting without evidence of diminishing for at least 16 days, whereas rAAV-GFP–injected rats showed a continued rise in BP. Rats treated with rAAV-α2B-AS treated had a 45% to 65% decrease in α2B-AR protein levels in key regulatory regions of the brain. Neither group had signs of immunologic response to the virus injection. Conclusions These results indicate that our construct, when given by ICV means, could reach multiple sites of the central nervous system relevant to BP regulation and could safely inhibit the central α2B-adrenergic receptor, thereby achieving prolonged reversal of salt-induced hypertension.