Endothelial dysfunction of resistance vessels in female apolipoprotein E-deficient mice

<p>Abstract</p> <p>Background</p> <p>The effects of hypercholesterolemia on vasomotricity in apolipoprotein E-deficient (ApoE) mice, a murine model of spontaneous atherosclerosis, are still unclear. The studies were mostly performed in conductance vessels from male mice fed a high-fat diet. In the present study, we evaluated the endothelial function of resistance vessels from normal C57BL/6 (C57) and hypercholesterolemic (ApoE) female mice in both normal and ovariectomized conditions.</p> <p>Methods</p> <p>Twenty week-old C57 and ApoE mice underwent ovariectomy or sham surgery and were studied 30 days later. The vascular reactivities to norepinephrine (NE, 10^-9to 2 × 10^-3mol/L), acetylcholine (ACh) and sodium nitroprusside (SNP) (10^-10to 10^-3mol/L) were evaluated in the isolated mesenteric arteriolar bed through dose-response curves.</p> <p>Results</p> <p>ACh-induced relaxation was significantly reduced (P < 0.05) in ApoE compared with C57 animals, as indicated by both the maximal response (37 ± 4% vs. 72 ± 1%) and the LogEC₅₀(-5.67 ± 0.18 vs. -6.23 ± 0.09 mol/L). Ovariectomy caused a significant impairment in ACh-induced relaxation in the C57 group (maximal response: 61 ± 4%) but did not worsen the deficient state of relaxation in ApoE animals (maximal response: 39 ± 5%). SNP-induced vasorelaxation and NE-induced vasoconstriction were similar in ApoE and C57 female mice.</p> <p>Conclusion</p> <p>These data show an impairment of endothelial function in the resistance vessels of spontaneously atherosclerotic (ApoE-deficient) female mice compared with normal (C57) female mice. The endothelial dysfunction in hypercholesterolemic animals was so marked that ovariectomy, which impaired endothelial function in C57 mice, did not cause additional vascular damage in ApoE-deficient mice.</p

Oral P. gingivalis infection alters the vascular reactivity in healthy and spontaneously atherosclerotic mice

<p>Abstract</p> <p>Background</p> <p>Considering that recent studies have demonstrated endothelial dysfunction in subjects with periodontitis and that there is no information about vascular function in coexistence of periodontitis and atherosclerosis, we assessed the impact of oral inoculation with the periodontal pathogen <it>Porphyromonas gingivalis </it>on vascular reactivity in healthy and hypercholesterolemic apolipoprotein E-deficient (ApoE) mice. <it>In vitro </it>preparations of mesenteric arteriolar bed were used to determine the vascular responses to acetylcholine, sodium nitroprusside and phenylephrine (PE).</p> <p>Results</p> <p>Alveolar bone resorption, an evidence of periodontitis, was assessed and confirmed in all infected mice. Acetylcholine- and sodium nitroprusside-induced vasorelaxations were similar among all groups. Non-infected ApoE mice were hyperreactive to PE when compared to non-infected healthy mice. <it>P gingivalis </it>infection significantly enhanced the vasoconstriction to PE in both healthy and spontaneous atherosclerotic mice, when compared to their respective controls.</p> <p>Conclusions</p> <p>This study demonstrates that oral <it>P gingivalis </it>affects the alpha-adrenoceptor-mediated vascular responsiveness in both healthy and spontaneous atherosclerotic mice, reinforcing the association between periodontitis and cardiovascular diseases.</p

Endothelial Dysfunction in the Apolipoprotein E-deficient Mouse: insights into the influence of diet, gender and aging

Since the early 1990s, several strains of genetically modified mice have been developed as models for experimental atherosclerosis. Among the available models, the apolipoprotein E-deficient (apoE-/-) mouse is of particular relevance because of its propensity to spontaneously develop hypercholesterolemia and atherosclerotic lesions that are similar to those found in humans, even when the mice are fed a chow diet. The main purpose of this review is to highlight the key achievements that have contributed to elucidating the mechanisms pertaining to vascular dysfunction in the apoE-/- mouse. First, we summarize lipoproteins and atherosclerosis phenotypes in the apoE-/- mouse, and then we briefly discuss controversial evidence relative to the influence of gender on the development of atherosclerosis in this murine model. Second, we discuss the main mechanisms underlying the endothelial dysfunction of conducting vessels and resistance vessels and examine how this vascular defect can be influenced by diet, aging and gender in the apoE-/- mouse

Cardiac and vascular phenotypes in the apolipoprotein E-deficient mouse

Cardiovascular death is frequently associated with atherosclerosis, a chronic multifactorial disease and a leading cause of death worldwide. Genetically engineered mouse models have proven useful for the study of the mechanisms underlying cardiovascular diseases. The apolipoprotein E-deficient mouse has been the most widely used animal model of atherosclerosis because it rapidly develops severe hypercholesterolemia and spontaneous atherosclerotic lesions similar to those observed in humans. In this review, we provide an overview of the cardiac and vascular phenotypes and discuss the interplay among nitric oxide, reactive oxygen species, aging and diet in the impairment of cardiovascular function in this mouse model

Hypercholesterolemia promotes early renal dysfunction in apolipoprotein E-deficient mice

<p>Abstract</p> <p>Background</p> <p>Aging and dyslipidemia are processes which can lead to deleterious consequences to renal function. Therefore, the aim of this study was to determine the effects of both hypercholesterolemia and aging on renal function in mice.</p> <p>Methods</p> <p>Male hypercholesterolemic apolipoprotein E-deficient mice (ApoE, n = 13) and age-matched C57BL/6 control mice (C57, n = 15) were studied at 2 (young) and 8 (adult) month-old. At each time point, animals were placed in metabolic cages for 24 hours to urine volume and urinary creatinine quantification. Blood samples were collected for serum cholesterol, urea and creatinine measurements. Glomerular filtration rate (GFR) was estimated through creatinine clearance determination. Mesangial expansion was evaluated by Periodic Acid Schiff staining, renal fibrosis was determined through Masson's trichrome staining and neuronal nitric oxide synthase (nNOS) expression in the kidney was performed by Western Blotting. To statistical analysis two-way ANOVA followed by Fisher's <it>post hoc </it>test was used.</p> <p>Results</p> <p>Total plasma cholesterol was increased about 5-fold in ApoE mice at both time points compared to C57 animals. At 2-month-old, GFR was already markedly reduced in ApoE compared to C57 mice (187 ± 28 vs 358 ± 92 μL/min, p < 0.05). Adult C57 (-77%) and ApoE (-50%) mice also presented a significant reduction of GFR. In addition, serum urea was significantly increased in young ApoE animals compared to C57 mice (11 ± 1.3 vs 7 ± 0.9 mmol/L, p < 0.01). A significant mesangial expansion was observed at 2-month old ApoE mice compared to C57 mice (35 ± 0.6 vs 30 ± 0.9%, respectively, p < 0.05), which was aggravated at 8-month old animals (40 ± 3 and 35 ± 3%, respectively). Tubulointersticial fibrosis was augmented at both young (17 ± 2%, p < 0.05) and adult (20 ± 1%, p < 0.05) ApoE mice compared to respective C57 age controls (8 ± 1 and 12 ± 2%, respectively). The expression of nNOS was markedly reduced in a time-dependent manner in both strains.</p> <p>Conclusions</p> <p>These data show that both hypercholesterolemia and aging contribute to the loss of renal function in mice.</p

Cardiac and vascular changes in elderly atherosclerotic mice: the influence of gender

<p>Abstract</p> <p>Background</p> <p>Although advanced age is considered a risk factor for several diseases, the impact of gender on age-associated cardiovascular diseases, such as atherosclerotic processes and valvular diseases, remains not completely clarified. The present study was designed to assess aortic valve morphology and function and vascular damage in elderly using the apolipoprotein E knockout (ApoE KO) mouse. Our hypothesis was that advanced age-related cardiovascular changes are aggravated in atherosclerotic male mice.</p> <p>Methods</p> <p>The grade (0 to 4) of aortic regurgitation was evaluated through angiography. In addition, vascular lipid deposition and senescence were evaluated through histochemical analyses in aged male and female ApoE KO mice, and the results were compared to wild-type C57BL/6J (C57) mice.</p> <p>Results</p> <p>Aortic regurgitation was observed in 92% of the male ApoE KO mice and 100% of the male C57 mice. Comparatively, in age-matched female ApoE KO and C57 mice, aortic regurgitation was observed in a proportion of 58% and 53%, respectively. Histological analysis of the aorta showed an outward (positive) remodeling in ApoE KO mice (female: 1.86 ± 0.15; male: 1.89 ± 0.68) using C57 groups as reference values. Histochemical evaluation of the aorta showed lipid deposition and vascular senescence only in the ApoE KO group, which were more pronounced in male mice.</p> <p>Conclusion</p> <p>The data show that male gender contributes to the progression of aortic regurgitation and that hypercholesterolemia and male gender additively contribute to the occurrence of lipid deposition and vascular senescence in elderly mice.</p

Inhibition of phosphodiesterase 5 restores endothelial function in renovascular hypertension

Background: the clipping of an artery supplying one of the two kidneys (2K1C) activates the renin-angiotensin (Ang) system (RAS), resulting in hypertension and endothelial dysfunction. Recently, we demonstrated the intrarenal beneficial effects of sildenafil on the high levels of Ang II and reactive oxygen species (ROS) and on high blood pressure (BP) in 2K1C mice. Thus, in the present study, we tested the hypothesis that sildenafil improves endothelial function in hypertensive 2K1C mice by improving the NO/ROS balance.Methods: 2K1C hypertension was induced in C57BL/6 mice. Two weeks later, they were treated with sildenafil (40 mg/kg/day, via oral) or vehicle for 2 weeks and compared with sham mice. At the end of the treatment, the levels of plasma and intrarenal Ang peptides were measured. Endothelial function and ROS production were assessed in mesenteric arterial bed (MAB).Results: the 2K1C mice exhibited normal plasma levels of Ang I, II and 1-7, whereas the intrarenal Ang I and II were increased (similar to 35% and similar to 140%) compared with the Sham mice. Sildenafil normalized the intrarenal Ang I and II and increased the plasma (similar to 45%) and intrarenal (+15%) Ang 1-7. the 2K1C mice exhibited endothelial dysfunction, primarily due to increased ROS and decreased NO productions by endothelial cells, which were ameliorated by treatment with sildenafil.Conclusion: These data suggest that the effects of sildenafil on endothelial dysfunction in 2K1C mice may be due to interaction with RAS and restoring NO/ROS balance in the endothelial cells from MAB. Thus, sildenafil is a promising candidate drug for the treatment of hypertension accompanied by endothelial dysfunction and kidney disease.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)State Agency for the Development of Science and Technology (FAPES/Universal)Univ Fed Espirito Santo, Hlth Sci Ctr, Lab Translat Physiol, Vitoria, ES, BrazilEmescam Sch Hlth Sci, Vitoria, ES, BrazilUniversidade Federal de São Paulo, Dept Med, Div Nephrol, São Paulo, BrazilUniv Fed Espirito Santo, Hlth Sci Ctr, Pharmaceut Sci Grad Program, Vitoria, ES, BrazilUniv Fed Paraiba, Hlth Sci Ctr, Dept Physiol & Pathol, BR-58059900 Joao Pessoa, PB, BrazilUVV, Pharmaceut Sci Grad Program, Vila Velha, ES, BrazilFed Inst Educ Sci & Technol IFES, Vila Velha, ES, BrazilUniversidade Federal de São Paulo, Dept Med, Div Nephrol, São Paulo, BrazilCNPq: 302582/2011-8CNPq: 476525/2012-8CNPq: 305188/2012-7CNPq: 473177/2013-7State Agency for the Development of Science and Technology (FAPES/Universal): 012/2011State Agency for the Development of Science and Technology (FAPES/Universal): 54498465CNPq: 012/2009Web of Scienc

Sildenafil ameliorates oxidative stress and DNA damage in the stenotic kidneys in mice with renovascular hypertension

Background: Oxidative stress and DNA damage have been implicated in the pathogenesis of renovascular hypertension induced by renal artery stenosis in the two-kidney, one-clip (2K1C) Goldblatt model. Considering our previous report indicating that the chronic blockade of phosphodiesterase 5 with sildenafil (Viagra (R)) has marked beneficial effects on oxidative stress and DNA damage, we tested the hypothesis that sildenafil could also protect the stenotic kidneys of 2K1C hypertensive mice against oxidative stress and genotoxicity.Methods: the experiments were performed with C57BL6 mice subjected to renovascular hypertension by left renal artery clipping. Two weeks after clipping, the mice were treated with sildenafil (40 mg/kg/ day for 2 weeks, 2K1C-sildenafil group) or the vehicle (2K1C). These mice were compared with control mice not subjected to renal artery clipping (Sham). After hemodynamic measurements, the stenotic kidneys were assessed using flow cytometry to evaluate cell viability and the comet assay to evaluate DNA damage. Measurements of intracellular superoxide anions and hydrogen peroxide levels as well as nitric oxide bioavailability were also obtained.Results: Sildenafil treatment significantly reduced mean arterial pressure (15%), heart rate (8%), intrarenal angiotensin II (50%) and renal atrophy (36%). in addition, it caused a remarkable decrease of reactive oxygen species production. On the other hand, sildenafil increased nitric oxide levels relative to those in the nontreated 2K1C mice. Sildenafil treatment also significantly reduced the high level of kidney DNA damage that is a characteristic of renovascular hypertensive mice.Conclusions: Our data reveal that sildenafil has a protective effect on the stenotic kidneys of 2K1C mice, suggesting a new use of phosphodiesterase 5 inhibitors for protection against the DNA damage observed in the hypoperfused kidneys of individuals with renovascular hypertension. Further translational research is necessary to delineate the mechanisms involved in the prevention of renal stenosis in the clinical setting.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)State Agency for the Development of Science and Technology (FAPES)Univ Fed Espirito Santo, Hlth Sci Ctr, Lab Translat Physiol, Vitoria, ES, BrazilUniv Fed Paraiba, Hlth Sci Ctr, Dept Physiol & Pathol, BR-58059900 Joao Pessoa, Paraiba, BrazilUniversidade Federal de São Paulo, Dept Med, Div Nephrol, São Paulo, BrazilUniv Vila Velha, Pharmaceut Sci Grad Program, Vila Velha, ES, BrazilFed Inst Educ Sci & Technol IFES, Vila Velha, ES, BrazilUniversidade Federal de São Paulo, Dept Med, Div Nephrol, São Paulo, BrazilCNPq: 302582/2011-8CNPq: 476525/2012-8CNPq: 305188/2012-7CNPq: 473177/2013-7State Agency for the Development of Science and Technology (FAPES): 54498465CNPq: 012/2009Web of Scienc