Vascular and Central Activation of Peroxisome Proliferator-Activated Receptor-β Attenuates Angiotensin II-Induced Hypertension: Role of RGS-5

Activation of peroxisome proliferator-activated receptor-beta/delta (PPAR beta) lowers blood pressure in genetic and mineralocorticoid-induced hypertension. Regulator of G-protein-coupled receptor signaling 5 (RGS5) protein, which interferes in angiotensin II (AngII) signaling, is a target gene to PPAR beta. The aim of the present study was to examine whether PPAR beta activation in resistance arteries and brain tissues prevents the elevated blood pressure in AngII-induced hypertension and evaluate the role of RGS5 in this effect. C57BL/6J male mice were divided into five groups (control mice, PPAR beta agonist [4-[[[2-[3-Fluoro4-( trifluoromethyl) phenyl]-4-methyl-5-thiazolyl] methyl] thio]2- methylphenoxy] acetic acid (GW0742)-treated mice AngII-infused mice, GW0742-treated AngII-infused mice, and AngII-infused mice treated with GW0742 plus PPAR beta antagonist 3-[[[2-Methoxy-4-( phenylamino) phenyl] amino] sulfonyl]-2-thiophenecarboxylic acid methyl ester (GSK0660)) and were followed for 3 weeks. GW0742 prevented the increase in both arterial blood pressure and plasma noradrenaline levels and the higher reduction of blood pressure after ganglionic blockade, whereas it reduced the mesenteric arterial remodeling and the hyperresponsiveness to vasoconstrictors (AngII and endothelin-1) in AngII-infused mice. These effects were accompanied by an inhibition of NADPH oxidase expression and activity in the brain. Gene expression profiling revealed a marked loss of brainstem and vascular RGS5 in AngII-infused mice, which was restored by GW0742. GW0742-induced effects were abolished by GSK0660. Small interfering RNA targeting RGS5 caused augmented contractile response to AngII in resistance mesenteric arteries and blunted the inhibitory effect of GW0742 on this response. In conclusion, GW0742 exerted antihypertensive effects, restoring sympathetic tone and vascular structure and function in AngII-infused mice by PPAR beta activation in brain and vessels inhibiting AngII signaling as a result of RGS5 upregulation.