gw9662 and Hypertension

Vascular inflammation plays a critical role in the pathogenesis of cerebral aneurysms. Peroxisome proliferator-activated receptor γ (PPARγ) protects against vascular inflammation and atherosclerosis, whereas dominant-negative mutations in PPARγ promote atherosclerosis and vascular dysfunction. We tested the role of PPARγ in aneurysm formation and rupture. Aneurysms were induced with a combination of systemic infusion of angiotensin-II and local injection of elastase in (1) mice that received the PPARγ antagonist GW9662 or the PPARγ agonist pioglitazone, (2) mice carrying dominant-negative PPARγ mutations in endothelial or smooth muscle cells, and (3) mice that received the Cullin inhibitor MLN4924. Incidence of aneurysm formation, rupture, and mortality was quantified. Cerebral arteries were analyzed for expression of Cullin3, Kelch-like ECH-associated protein 1, nuclear factor (erythroid-derived 2)-like 2, NAD(P)H dehydrogenase (quinone)1 (NQO1), and inflammatory marker mRNAs. Neither pioglitazone nor GW9662 altered the incidence of aneurysm formation. GW9662 significantly increased the incidence of aneurysm rupture, whereas pioglitazone tended to decrease the incidence of rupture. Dominant-negative endothelial-specific PPARγ did not alter the incidence of aneurysm formation or rupture. In contrast, dominant-negative smooth muscle-specific PPARγ resulted in an increase in aneurysm formation (P<0.05) and rupture (P=0.05). Dominant-negative smooth muscle-specific PPARγ, but not dominant-negative endothelial-specific PPARγ, resulted in significant decreases in expression of genes encoding Cullin3, Kelch-like ECH-associated protein 1, and nuclear factor (erythroid-derived 2)-like 2, along with significant increases in tumor necrosis factor-α, monocyte chemoattractant protein-1, chemokine (C-X-C motif) ligand 1, CD68, matrix metalloproteinase-3, -9, and -13. MLN4924 did not alter incidence of aneurysm formation, but increased the incidence of rupture (P<0.05). In summary, endogenous PPARγ, specifically smooth muscle PPARγ, plays an important role in protecting from formation and rupture of experimental cerebral aneurysms in mice.

Topics: Aneurysm, Ruptured; Angiotensin II; Anilides; Animals; Cerebral Arteries; Endothelium, Vascular; Gene Expression Regulation; Genes, Dominant; Hypertension; Inflammation Mediators; Intracranial Aneurysm; Mice; Mice, Transgenic; Muscle, Smooth, Vascular; Mutation; Myocytes, Smooth Muscle; Organ Specificity; Pancreatic Elastase; Pioglitazone; PPAR gamma; Subarachnoid Hemorrhage; Thiazolidinediones; Up-Regulation; Vasculitis

Inflammation and renin-angiotensin system activity in the brain contribute to hypertension through effects on fluid intake, vasopressin release, and sympathetic nerve activity. We recently reported that activation of brain peroxisome proliferator-activated receptor (PPAR)-γ in heart failure rats reduced inflammation and renin-angiotensin system activity in the hypothalamic paraventricular nucleus and ameliorated the peripheral manifestations of heart failure. We hypothesized that the activation of brain PPAR-γ might have beneficial effects in angiotensin II-induced hypertension. Sprague-Dawley rats received a 2-week subcutaneous infusion of angiotensin II (120 ng/kg per minute) combined with a continuous intracerebroventricular infusion of vehicle, the PPAR-γ agonist pioglitazone (3 nmol/h) or the PPAR-γ antagonist GW9662 (7 nmol/h). Angiotensin II+vehicle rats had increased mean blood pressure, increased sympathetic drive as indicated by the mean blood pressure response to ganglionic blockade, and increased water consumption. PPAR-γ mRNA in subfornical organ and hypothalamic paraventricular nucleus was unchanged, but PPAR-γ DNA-binding activity was reduced. mRNA for interleukin-1β, tumor necrosis factor-α, cyclooxygenase-2, and angiotensin II type 1 receptor was augmented in both nuclei, and hypothalamic paraventricular nucleus neuronal activity was increased. The plasma vasopressin response to a 6-hour water restriction also increased. These responses to angiotensin II were exacerbated by GW9662 and ameliorated by pioglitazone, which increased PPAR-γ mRNA and PPAR-γ DNA-binding activity in subfornical organ and hypothalamic paraventricular nucleus. Pioglitazone and GW9662 had no effects on control rats. The results suggest that activating brain PPAR-γ to reduce central inflammation and brain renin-angiotensin system activity may be a useful adjunct in the treatment of angiotensin II-dependent hypertension.

Topics: Angiotensin II; Anilides; Animals; Blood Pressure; Brain; Disease Models, Animal; Hypertension; Infusions, Intraventricular; Infusions, Subcutaneous; Male; Pioglitazone; PPAR gamma; Rats; Rats, Sprague-Dawley; Renin-Angiotensin System; Sympathetic Nervous System; Thiazolidinediones; Ventricular Remodeling

Targeted disruption of the Alox15 gene makes mice resistant to angiotensin II-, DOCA/salt-, and N(ω)-nitro-L-arginine methyl ester (L-NAME)-induced experimental hypertension. Macrophages, a primary source of Alox15, are facilitating this resistance, but the underlying mechanism is not known. Because Alox15 metabolites are peroxisome proliferator-activated receptor (PPAR)γ agonists, we hypothesized that activation of macrophage PPARγ is the key step in Alox15 mediation of hypertension. Thioglycollate, used for macrophage elicitation, selectively upregulated PPARγ and its target gene CD36 in peritoneal macrophages of both wild-type (WT) and Alox15(-/-) mice. Moreover, thioglycollate-injected Alox15(-/-) mice became hypertensive upon L-NAME treatment. A similar hypertensive effect was observed with adoptive transfer of thioglycollate-elicited Alox15(-/-) macrophages into Alox15(-/-) recipient mice. The role of PPARγ was further specified by using the selective PPARγ antagonist GW9662. WT mice treated with 50 μg/kg daily dose of GW9662 for 12 days became resistant to L-NAME-induced hypertension. The PPARγ antagonist treatment also prevented L-NAME-induced hypertension in thioglycollate-injected Alox15(-/-) mice, indicating a PPARγ-mediated effect in macrophage elicitation and the resultant hypertension. These results indicate a regulatory role for macrophage-localized PPARγ in L-NAME-induced experimental hypertension.

Topics: Anilides; Animals; Arachidonate 12-Lipoxygenase; Arachidonate 15-Lipoxygenase; CD36 Antigens; Hypertension; Macrophages; Mice; Mice, Inbred C57BL; NG-Nitroarginine Methyl Ester; PPAR gamma; Thioglycolates; Up-Regulation

This study investigated the effects of the peroxisome proliferator-activated receptor alpha (PPAR-α) agonist, Fenofibrate, on the secretion of vascular endothelial contraction factors in hypertensive rats to elucidate its possible mechanisms. The vascular ring contraction experiment was used to observe whether rat vascular tension of clean grade spontaneously hypertensive rats (SHR) changes after 1-h incubation of 0.1, 1.0, 10.0 μM Fenofibrate with 10.0 μM Fenofibrate, a PPAR-α antagonist (MK866), and a PPAR-γ antagonist (GW9662) in SHR. The results were compared with Wistar Kyoto rats. Enzyme-linked immunosorbent assay was used to detect the secretion of the serum vascular endothelial contraction factor prostacyclin-1α (PGF-1α), PGF-2α, and thromboxane B2 (TXB2). Western blot was used to detect COX-1 protein expression. A quantity of 10.0 μM Fenofibrate significantly reduced vasoconstriction in SHR compared to the control group (P = 0.013). The PPAR-α antagonist, MK866, significantly improved the vascular contractility of SHR when incubated with 10.0 μM Fenofibrate (P = 0.021). The PPAR-γ antagonist, GW9662, had no significant effect on the vascular contractility of SHR when incubated with 10.0 μM Fenofibrate (P = 0.071). The isolated aorta of SHR released significantly lower PGF- 1α (P = 0.014), PGF-2α (P = 0.023), and TXB2 (P = 0.017) levels in the 10.0 μM Fenofibrate group compared to the control group. COX-1 expression of SHR rat vascular endothelium was significantly depressed in the 10.0 μM Fenofibrate group compared to the control group (P = 0.027). In conclusion, Fenofibrate reduces the secretion of vascular endothelial contraction factors in hypertensive rats, which might arise through the endothelium influencing COX-1 expression.

Topics: Anilides; Animals; Aorta; Cyclooxygenase 1; Dinoprost; Dose-Response Relationship, Drug; Endothelium, Vascular; Fenofibrate; Gene Expression; Hypertension; Hypolipidemic Agents; Male; Membrane Proteins; PPAR alpha; PPAR gamma; Prostaglandins F; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Thromboxane B2; Tissue Culture Techniques; Vasoconstriction

Telmisartan and losartan, angiotensin II type 1 (AT1) receptor antagonists, are used to manage hypertension. We previously reported that telmisartan, a partial agonist of peroxisome proliferator-activated receptor-γ (PPAR-γ), exhibited stronger vasoprotection than the same dose of losartan in normotensive chronic kidney disease (CKD) rats. We investigated whether telmisartan could inhibit vascular dysfunction in hypertensive CKD rats, via both AT1 receptor blockade and PPAR-γ activation, more effectively than losartan, which decreased blood pressure to a similar extent as telmisartan.. Two or three branches of the left renal artery were ligated and the right kidney was removed to make hypertensive CKD rats. Telmisartan (5 mg/kg), losartan (10 mg/kg) or telmisartan plus the PPAR-γ antagonist GW9662 was administered.. Blood pressure was increased in CKD rats. Telmisartan and losartan decreased blood pressure to the same levels. Impaired endothelium-dependent vasodilation, hyperplasia and decreased phospho-eNOS (Ser(1177)) expression in CKD rat aortas were improved by telmisartan. The aortic infiltration by macrophages and expression of osteopontin were enhanced in CKD rats and suppressed by telmisartan. GW9662 partly canceled the normalization of vascular dysfunction. While losartan attenuated vascular changes, the extent of this attenuation was greater in the telmisartan-treated group.. Telmisartan exhibited vasoprotection via PPAR-γ agonistic properties in hypertensive CKD rats.

Topics: Angiotensin II Type 1 Receptor Blockers; Anilides; Animals; Aorta; Benzimidazoles; Benzoates; Blood Pressure; Disease Models, Animal; Drug Partial Agonism; Endothelium, Vascular; Hypertension; Losartan; Male; Nitric Oxide Synthase Type III; PPAR gamma; Rats; Rats, Wistar; Telmisartan; Vasodilation

Inactivating peroxisome proliferator-activated receptor-γ (PPARγ) mutations lead to a syndrome of familial partial lipodystrophy (FPLD3) associated with early-onset severe hypertension. PPARγ can repress the vascular renin-angiotensin system (RAS) and angiotensin II receptor 1 expression. We evaluated the relationships between PPARγ inactivation and cellular RAS using FPLD3 patients' cells and human vascular smooth muscle cells expressing mutant or wild-type PPARγ. Approach and Results- We identified 2 novel PPARG mutations, R165T and L339X, located in the DNA and ligand-binding domains of PPARγ, respectively in 4 patients from 2 FPLD3 families. In cultured skin fibroblasts and peripheral blood mononuclear cells from the 4 patients and healthy controls, we compared markers of RAS activation, oxidative stress, and inflammation, and tested the effect of modulators of PPARγ and angiotensin II receptor 1. We studied the impact of the 2 mutations on the transcriptional activity of PPARγ and on the vascular RAS in transfected human vascular smooth muscle cells. Systemic RAS was not altered in patients. However, RAS markers were overexpressed in patients' fibroblasts and peripheral blood mononuclear cells, as in vascular cells expressing mutant PPARγ. Angiotensin II-mediated mitogen-activated protein kinase activity increased in patients' fibroblasts, consistent with RAS constitutive activation. Patients' cells also displayed oxidative stress and inflammation. PPARγ activation and angiotensin II receptor 1 mRNA silencing reversed RAS overactivation, oxidative stress, and inflammation, arguing for a role of angiotensin II receptor 1 in these processes.. Two novel FPLD3-linked PPARG mutations are associated with a defective transrepression of cellular RAS leading to cellular dysfunction, which might contribute to the specific FPLD3-linked severe hypertension.

Topics: Adult; Aged; Amino Acid Sequence; Angiotensin II; Anilides; Animals; Case-Control Studies; Enzyme Activation; Female; Fibroblasts; Genetic Predisposition to Disease; HEK293 Cells; Humans; Hypertension; Inflammation Mediators; Leukocytes, Mononuclear; Lipodystrophy, Familial Partial; Male; Mitogen-Activated Protein Kinases; Molecular Sequence Data; Muscle, Smooth, Vascular; Mutation; Myocytes, Smooth Muscle; Oxidative Stress; Phenotype; PPAR gamma; Receptor, Angiotensin, Type 1; Renin-Angiotensin System; RNA Interference; Rosiglitazone; Severity of Illness Index; Skin; Thiazolidinediones; Transfection; Young Adult

It has been shown that the calcium antagonist nifedipine upregulates superoxide dismutase (SOD). Although the peroxisome proliferator-activated receptor (PPAR) response element is located in the promoter region of Cu/ZnSOD, it remains unclear whether nifedipine upregulates PPARs and inhibits vascular remodeling. We hypothesthized that nifedipine activates PPARgamma, inhibits vascular remodeling, and improves vascular function in hypertension.. Stroke-prone spontaneously hypertensive rats (SHRSP) were treated with vehicle, nifedipine, and PPARgamma selective antagonist GW9662 with nifedipine.. Systolic blood pressure in the three SHRSP groups was higher (p <0.01), and the left ventricular weight/body weight ratio was greater (p <0.01) than in the Wistar-Kyoto rat (WKY) group with no differences observed among the three SHRSP groups. In the SHRSP heart, nifedipine significantly inhibited intramyocardial arterial remodeling and perivascular fibrosis, and reduced oxidative stress, while it significantly restored adiponectin and the smooth muscle cell (SMC) phenotype, and selectively restored PPARgamma and Cu/ZnSOD expression/activities to their levels in the WKY rat heart. Furthermore, nifedipine induced a dose-dependent increase in PPARgamma expression in cultured vascular SMCs. These effects of nifedipine were completely abolished by the co-administration of GW9662 with nifedipine. Nifedipine treatment significantly improved acetylcholine-induced relaxation by 27% compared with the vehicle SHRSP group, but it was still significantly impaired by 20% compared with the WKY group.. Nifedipine may inhibit vascular remodeling and improve vascular function by selective activation of PPARgamma through the activation of Cu/ZnSOD in hypertension.

Topics: Anilides; Animals; Aorta; Blood Pressure; Calcium Channel Blockers; Cells, Cultured; Endothelium, Vascular; Hypertension; Immunoblotting; Male; Mesenteric Arteries; Muscle, Smooth, Vascular; Nifedipine; Oxidative Stress; PPAR gamma; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Stroke; Superoxide Dismutase; Superoxides

Thiazolidinediones (TZDs) are synthetic agonists of the ligand-activated transcription factor peroxisome proliferator-activated receptor-gamma (PPARgamma). TZDs are known to curtail inflammation associated with peripheral organ ischemia. As inflammation precipitates the neuronal death after stroke, we tested the efficacy of TZDs in preventing brain damage following transient middle cerebral artery occlusion (MCAO) in adult rodents. As hypertension and diabetes complicate the stroke outcome, we also evaluated the efficacy of TZDs in hypertensive rats and type-2 diabetic mice subjected to transient MCAO. Pre-treatment as well as post-treatment with TZDs rosiglitazone and pioglitazone significantly decreased the infarct volume and neurological deficits in normotensive, normoglycemic, hypertensive and hyperglycemic rodents. Rosiglitazone neuroprotection was not enhanced by retinoic acid x receptor agonist 9-cis-retinoic acid, but was prevented by PPARgamma antagonist GW9662. Rosiglitazone significantly decreased the post-ischemic intercellular adhesion molecule-1 expression and extravasation of macrophages and neutrophils into brain. Rosiglitazone treatment curtailed the post-ischemic expression of the pro-inflammatory genes interleukin-1beta, interleukin-6, macrophage inflammatory protein-1alpha, monocyte chemoattractant protein-1, cyclooxygenase-2, inducible nitric oxide synthase, early growth response-1, CCAAT/enhancer binding protein-beta and nuclear factor-kappa B, and increased the expression of the anti-oxidant enzymes catalase and copper/zinc-superoxide dismutase. Rosiglitazone also increased the expression of the anti-inflammatory gene suppressor of cytokine signaling-3 and prevented the phosphorylation of the transcription factor signal transducer and activator of transcription-3 after focal ischemia. Thus, PPARgamma activation with TZDs might be a potent therapeutic option for preventing inflammation and neuronal damage after stroke with promise in diabetic and hypertensive subjects.

Topics: Anilides; Animals; Cerebral Infarction; Chemotaxis, Leukocyte; Cytokines; Diabetes Mellitus, Type 2; Disease Models, Animal; Encephalitis; Hypertension; Intercellular Adhesion Molecule-1; Ischemic Attack, Transient; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Neuroprotective Agents; Pioglitazone; PPAR gamma; Rats; Rats, Inbred SHR; Rats, Sprague-Dawley; Rosiglitazone; Superoxide Dismutase; Superoxide Dismutase-1; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins; Thiazolidinediones

Phytoestrogens are considered to be natural selective estrogen receptor modulators exerting antioxidant activity and improving vascular function. However, the mechanisms responsible for their antioxidative effects remain largely unknown. This study tested the hypothesis that genistein may provide significant endothelial protection by antioxidative effects through attenuating NADPH oxidase expression and activity. The results showed that genistein suppressed the expressions of the p22phox NADPH oxidase subunit and angiotensin II (Ang II) type 1 (AT1) receptor in a concentration- and time-dependent manner in aortic endothelial cells from stroke-prone spontaneously hypertensive rats examined by Western blot analysis. Treatment with genistein also remarkably reduced the Ang II-induced superoxide by the reduction of nitroblue tetrazolium, inhibited nitrotyrosine formation, and attenuated endothelin-1 production by ELISA via the stimulation of Ang II. However, when cells were pretreated with ICI-182780, an estrogen-receptor antagonist, at a concentration of 50 micromol/l for 30 min and then co-incubated with ICI-182780 and genistein for 24 h, the inhibitory effect of genistein was not blocked. In contrast, the inhibitory effect of genistein treatment was partially reversed by 30-min pretreatment of endothelial cells with GW9662, a peroxisome proliferator-activated receptor gamma (PPARgamma) antagonist. Genistein thus appears to act as an antioxidant at the transcription level by the downregulation of p22phox and AT1 receptor expression. Our data also showed that the PPARgamma pathway was involved, at least in part, in the inhibitory effect of genistein on the expression of p22phox and AT1 receptors. The endothelial-protective effects of phytoestrogen may contribute to improvement of cardiovascular functions.

Topics: Angiotensin II; Anilides; Animals; Aorta, Thoracic; Cells, Cultured; Endothelin-1; Endothelium, Vascular; Enzyme Inhibitors; Estradiol; Estrogen Antagonists; Fulvestrant; Genistein; Hypertension; Male; Membrane Transport Proteins; NADPH Dehydrogenase; NADPH Oxidases; Phosphoproteins; PPAR gamma; Rats; Rats, Inbred SHR; Receptor, Angiotensin, Type 1; Signal Transduction; Stroke; Superoxides; Tyrosine; Vasoconstrictor Agents