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Probiotics exert cardiovascular protective effects in genetic hypertension related to the improvement of vascular pro-oxidative and pro-inflammatory status.

We propose that Q3GA behaves as a quercetin carrier in plasma, which deconjugates in situ releasing the aglycone which is the final effector.

BackgroundChronic oral quercetin reduces blood pressure and restores endothelial dysfunction in hypertensive animals. However, quercetin (aglycone) is usually not present in plasma, because it is rapidly metabolized into conjugated, mostly inactive, metabolites. The aim of the study is to analyze whether deconjugation of these metabolites is involved in the blood pressure lowering effect of quercetin.Methodology/Principal FindingsWe have analyzed the effects on blood pressure and vascular function in vitro of the conjugated metabolites of quercetin (quercetin-3-glucuronide, Q3GA; isorhamnetin-3-glucuronide, I3GA; and quercetin-3′-sulfate, Q3'S) in spontaneously hypertensive rats (SHR). Q3GA and I3GA (1 mg/kg i.v.), but not Q3'S, progressively reduced mean blood pressure (MBP), measured in conscious SHR. The hypotensive effect of Q3GA was abolished in SHR treated with the specific inhibitor of β-glucuronidase, saccharic acid 1,4-lactone (SAL, 10 mg/ml). In mesenteric arteries, unlike quercetin, Q3GA had no inhibitory effect in the contractile response to phenylephrine after 30 min of incubation. However, after 1 hour of incubation Q3GA strongly reduced this contractile response and this effect was prevented by SAL. Oral administration of quercetin (10 mg/Kg) induced a progressive decrease in MBP, which was also suppressed by SAL.ConclusionsConjugated metabolites are involved in the in vivo antihypertensive effect of quercetin, acting as molecules for the plasmatic transport of quercetin to the target tissues. Quercetin released from its glucuronidated metabolites could be responsible for its vasorelaxant and hypotensive effect.

Abstract-Activation of nuclear hormone receptor peroxisome proliferator-activated receptor ␤/␦ (PPAR␤) has been shown to improve insulin resistance and plasma high-density lipoprotein levels, but nothing is known about its effects in genetic hypertension. We studied whether the PPAR␤ agonist GW0742 might exert antihypertensive effects in spontaneously hypertensive rats (SHRs). The rats were divided into 4 groups, Wistar Kyoto rat-control, Wistar Kyoto rat-treated (GW0742, 5 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 by oral gavage), SHR-control, and SHR-treated, and followed for 5 weeks. GW0742 induced a progressive reduction in systolic arterial blood pressure and heart rate in SHRs and reduced the mesenteric arterial remodeling, the increased aortic vasoconstriction to angiotensin II, and the endothelial dysfunction characteristic of SHRs. These effects were accompanied by a significant increase in endothelial NO synthase activity attributed to upregulated endothelial NO synthase and downregulated caveolin 1 protein expression. Moreover, GW0742 inhibited vascular superoxide production, downregulated p22 phox and p47 phox proteins, decreased both basal and angiotensin II-stimulated NADPH oxidase activity, inhibited extracellular-regulated kinase 1/2 activation, and reduced the expression of the proinflammatory and proatherogenic genes, interleukin 1␤, interleukin 6, or intercellular adhesion molecule 1. None of these effects were observed in Wistar Kyoto rats. PPAR␤ activation, both in vitro and in vivo, increased the expression of the regulators of G protein-coupled signaling proteins RGS4 and RGS5, which negatively modulated the vascular actions of angiotensin II. PPAR␤ activation exerted antihypertensive effects, restored the vascular structure and function, and reduced the oxidative, proinflammatory, and proatherogenic status of SHRs. We propose PPAR␤ as a new therapeutic target in hypertension. T he peroxisome proliferator-activated receptors (PPARs) PPAR␣, PPAR␤/␦, and PPAR␥ are members of the nuclear hormone receptor superfamily. PPARs were initially believed to regulate genes involved only in lipid and glucose metabolism. 1 However, in recent years, evidence suggests that activation of PPAR␣ or PPAR␥ may exert cardiovascular protection beyond their metabolic effects. 2 In fact, PPAR␣ or PPAR␥ agonists exert antihypertensive effects in both human and animal models with or without metabolic disorders. [3][4][5][6] The mechanisms underlying the beneficial effects of PPARs beyond glucose and lipid metabolism may relate to their anti-inflammatory and antioxidant actions. 5 Thus, activation of both PPAR␣ or PPAR␥ antagonizes angiotensin II (Ang II) actions, including the activation of NADPH oxidase and the generation of reactive oxygen species, as well as the increase in proinflammatory mediators and adhesion molecules in blood vessels. 5,6 Activation of PPAR␤/␦ (PPAR␤) also exhibits antiinflammatory properties in the vessel wall by inhibiting the expression of vascular cell adhesion molecule 1 and monocyte chemoattractant prote...

The effects of chronic consumption of oleuropein-enriched (15% w/w) olive leaf extract (OLE) on blood pressure, endothelial function, and vascular oxidative and inflammatory status in spontaneously hypertensive rats (SHR) were evaluated. Ten Wistar Kyoto rats (WKY) and twenty SHR were randomly assigned to three groups: a control WKY group, a control SHR group and a SHR group treated with OLE (30 mg kg(-1)) for 5 weeks. Long-term administration of OLE reduced systolic blood pressure, heart rate, and cardiac and renal hypertrophy. OLE treatment reversed the impaired aortic endothelium-dependent relaxation to acetylcholine observed in SHR. OLE restored aortic eNOS phosphorylation at Ser-1177 and Thr-495 and increased eNOS activity. OLE eliminated the increased aortic superoxide levels, and reduced the elevated NADPH oxidase activity, as a result of reduced NOX-1 and NOX-2 mRNA levels in SHR. OLE reduced the enhanced vascular TLR4 expression by inhibition of mitogen-activated protein kinase (MAPK) signaling with the subsequent reduction of proinflammatory cytokines. In conclusion, OLE exerts antihypertensive effects on genetic hypertension related to the improvement of vascular function as a result of reduced pro-oxidative and pro-inflammatory status.

Quercetin is a dietary flavonoid which exerts vasodilator, antiplatelet and antiproliferative effects and reduces blood pressure, oxidative status and end-organ damage in humans and animal models of systemic hypertension. We hypothesized that oral quercetin treatment might be protective in a rat model of pulmonary arterial hypertension. Three weeks after injection of monocrotaline, quercetin (10 mg/kg/d per os) or vehicle was administered for 10 days to adult Wistar rats. Quercetin significantly reduced mortality. In surviving animals, quercetin decreased pulmonary arterial pressure, right ventricular hypertrophy and muscularization of small pulmonary arteries. Classic biomarkers of pulmonary arterial hypertension such as the downregulated expression of lung BMPR2, Kv1.5, Kv2.1, upregulated survivin, endothelial dysfunction and hyperresponsiveness to 5-HT were unaffected by quercetin. Quercetin significantly restored the decrease in Kv currents, the upregulation of 5-HT2A receptors and reduced the Akt and S6 phosphorylation. In vitro, quercetin induced pulmonary artery vasodilator effects, inhibited pulmonary artery smooth muscle cell proliferation and induced apoptosis. In conclusion, quercetin is partially protective in this rat model of PAH. It delayed mortality by lowering PAP, RVH and vascular remodeling. Quercetin exerted effective vasodilator effects in isolated PA, inhibited cell proliferation and induced apoptosis in PASMCs. These effects were associated with decreased 5-HT2A receptor expression and Akt and S6 phosphorylation and partially restored Kv currents. Therefore, quercetin could be useful in the treatment of PAH.

The present study analysed the effects of the flavanol (2)-epicatechin in rats after chronic inhibition of NO synthesis with N G -nitro-L-arginine methyl ester (L-NAME), at doses equivalent to those achieved in the studies involving human subjects. Wistar rats were randomly divided into four groups: (1) control-vehicle, (2) L-NAME, (3) L-NAME-epicatechin 2 (L-NAME-Epi 2) and (4) L-NAME-epicatechin 10 (L-NAME-Epi 10). Rats were daily given by oral administration for 4 weeks: vehicle, (2)-epicatechin 2 or 10 mg/kg. Animals in the L-NAME groups daily received L-NAME 75 mg/100 ml in drinking-water. The evolution in systolic blood pressure and heart rate, and morphological and plasma variables, proteinuria, vascular superoxide, reactivity and protein expression at the end of the experiment were analysed. Chronic (2 )-epicatechin treatment did not modify the development of hypertension and only weakly affected the endothelial dysfunction induced by L-NAME but prevented the cardiac hypertrophy, the renal parenchyma and vascular lesions and proteinuria, and blunted the prostanoid-mediated enhanced endothelium-dependent vasoconstrictor responses and the cyclo-oxygenase-2 and endothelial NO synthase (eNOS) up-regulation. Furthermore, (2)-epicatechin also increased Akt and eNOS phosphorylation and prevented the L-NAME-induced increase in systemic (plasma malonyldialdehyde and urinary 8-iso-PGF 2a ) and vascular (dihydroethidium staining, NADPH oxidase activity and p22 phox up-regulation) oxidative stress, proinflammatory status (intercellular adhesion molecule-1, IL-1b and TNFa up-regulation) and extracellular-signal-regulated kinase 1/2 phosphorylation. The present study shows for the first time that chronic oral administration of (2)-epicatechin does not improve hypertension but reduced pro-atherogenic pathways such as oxidative stress and proinflammatory status of the vascular wall induced by blockade of NO production.Key words: (2 )-Epicatechin: N G -nitro-L-arginine methyl ester: Hypertension: Superoxide: Inflammation Flavanols, such as (2)-epicatechin, catechin and their oligomers, represent a major class of flavonoids that are commonly present in most higher plants, and with high content in certain foods, such as grapes, tea and cocoa. Several epidemiological investigations and dietary interventions in human subjects using flavanol-containing foods indicate an inverse relationship between flavanol intake and the risk of CVD (1 -5) . A very wide range of biological actions of a flavanol-rich diet support these potential cardiovascular protective effects including the improvement of vasodilation (6 -8) , blood pressure (9,10) , insulin resistance (11) , the attenuation of platelet reactivity (12) , and the improvement of immune responses and antioxidant defence system (13) . However, little is known about the molecular mechanisms of flavanol-mediated bioactivities in both humans and animals. The reasons for these shortcomings are, at least in part, based on the fact that food matrices contain a multitude of ...