Dehydroepiandrosterone protects against oxidative stress-induced endothelial dysfunction in ovariectomized rats

Cardiovascular disease is less frequent in premenopausal women than in age-matched men or postmenopausal women. Moreover, the marked age-related decline in serum dehydroepiandrosterone (DHEA) level has been associated to cardiovascular disease. The aim of this study was to evaluate the effects of DHEA treatment on vascular function in ovariectomized rats. At 8 weeks of age, female Wistar rats were ovariectomized (OVX) or sham (SHAM) operated and 8 weeks after surgery both groups were treated with vehicle or DHEA (10 mg kg-1 week-1) for 3 weeks. Aortic rings were used to evaluate the vasoconstrictor response to phenylephrine (PHE) and the relaxation responses to acetylcholine (ACh) and sodium nitroprusside (SNP). Tissue reactive oxygen species (ROS) production and SOD, NADPH oxidase and eNOS protein expression were analysed. PHE-induced contraction was increased in aortic rings from OVX compared to SHAM, associated with a reduction in NO bioavailability. Furthermore, the relaxation induced by ACh was reduced in arteries from OVX, while SNP relaxation did not change. The incubation of aortic rings with SOD or apocynin restored the enhanced PHE-contraction and the impaired ACh-relaxation only in OVX. DHEA treatment corrected the increased PHE contraction and the impaired ACh-induced relaxation observed in OVX by an increment in NO bioavailability and decrease in ROS production. Besides, DHEA treatment restores the reduced Cu/Zn-SOD protein expression and eNOS phosphorylation and the increased NADPH oxidase protein expression in the aorta of OVX rats. The present results suggest an important action of DHEA, improving endothelial function in OVX rats by acting as an antioxidant and enhancing the NO bioavailability.

Aldosterone induces endothelial dysfunction in resistance arteries from normotensive and hypertensive rats by increasing thromboxane A(2) and prostacyclin

Background and purpose: The present study was designed to assess whether cyclooxygenase-2 (COX-2) activation is involved in the effects of chronic aldosterone treatment on endothelial function of mesenteric resistance arteries (MRA) from Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Experimental approach: Relaxation to acetylcholine was measured in MRA from both untreated and aldosterone-treated strains. Vasomotor responses to prostacyclin and U46619 were also analysed. Release of 6-oxo-prostaglandin (PG)F(1 alpha) and thromboxane B(2) (TxB(2)) was determined by enzyme immunoassay. COX-2 protein expression was measured by western blot. Key results: Aldosterone reduced acetylcholine relaxation in MRA from both strains. In MRA from both aldosterone-treated strains the COX-1/2 or COX-2 inhibitor (indomethacin and NS-398, respectively), Tx2 synthesis inhibitor (furegrelate), prostacyclin synthesis inhibitor (tranylcypromine) or Tx2/PG2 receptor antagonist (SQ 29 548), but not COX-1 inhibitor SC-560, increased acetylcholine relaxation. In untreated rats this response was increased only in SHR. Prostacyclin elicited a biphasic vasomotor response: lower concentrations elicited relaxation, whereas higher concentrations elicited contraction that was reduced by SQ 29 548. Aldosterone increased the acetylcholine-stimulated production of 6-oxo-PGF(1 alpha) and TxB(2) in MRA from both strains. COX-2 expression was higher in both strains of rats treated with aldosterone. Conclusions and implications: Chronic treatment with aldosterone impaired endothelial function in MRA under normotensive and hypertensive conditions by increasing COX-2-derived prostacyclin and thromboxane A(2). As endothelial dysfunction participates in the pathogenesis of many cardiovascular disorders we hypothesize that anti-inflammatory drugs, specifically COX-2 inhibitors, could ameliorate vascular damage in patients with elevated aldosterone production.

Oxidative stress and inflammatory mediators contribute to endothelial dysfunction in high-fat diet-induced obesity in mice

Objective We investigated the effects of high-fat diet-induced obesity on vascular proinflammatory factors and oxidative stress on endothelium-dependent relaxation of the aorta. Methods Female Swiss mice were submitted to a high-fat diet for 16 weeks. At the end of the experimental period, we evaluated blood pressure, relaxation in response to acetylcholine in aortic rings in the absence and the presence of the superoxide anion scavenger, superoxide dismutase (SOD, 150 U/ml), and the nuclear factor (NF)-kappa B inhibitor, sodium salicylate (5 mmol/l). Aortic protein expression of endothelial nitric oxide synthase, Cu/Zn-SOD, NF-kappa B, I kappa B-alpha, and proinflammatory cytokines were also evaluated. Results Obese mice presented higher systolic and diastolic blood pressure than control mice (P<0.05). The relaxation of aortas to acetylcholine, but not to sodium nitroprusside, was significantly decreased in obese mice and was corrected by both SOD and sodium salicylate (P<0.05). The protein expression of endothelial nitric oxide synthase and Cu/Zn-SOD was significantly decreased in aorta from obese mice (P<0.05). Total p65 NF-kappa B subunit protein expression was not affected by obesity, but the protein expression of NF-kappa B inhibitor I kappa B-alpha was lower in aorta from obese mice (P<0.05). There were no significant differences in the interleukin (IL)-1 beta and IL-6 protein expression between groups. In contrast, the expression of TNF-alpha was significantly increased in aortas from obese mice. Conclusion Our resultssuggest that the reducedantioxidant defense and the local NF-kappa B pathway play an important role in the impairment of endothelium-dependent relaxation in aorta from obese mice. J Hypertens 28: 2111-2119 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Saturated Fatty Acid-Induced Insulin Resistance Is Associated With Mitochondrial Dysfunction in Skeletal Muscle Cells

Increased plasma levels of free fatty acids (FFA) occur in states of insulin resistance such as obesity and type 2 diabetes mellitus. These high levels of plasma FFA are proposed to play an important role for the development of insulin resistance but the mechanisms involved are still unclear. This study investigated the effects of saturated and unsaturated FFA on insulin sensitivity in parallel with mitochondrial function. C2C12 myotubes were treated for 24 h with 0.1 mM of saturated (palmitic and stearic) and unsaturated (oleic, linoleic, eicosapentaenoic, and docosahexaenoic) FFA. After this period, basal and insulin-stimulated glucose metabolism and mitochondrial function were evaluated. Saturated palmitic and stearic acids decreased insulin-induced glycogen synthesis, glucose oxidation, and lactate production. Basal glucose oxidation was also reduced. Palmitic and stearic acids impaired mitochondrial function as demonstrated by decrease of both mitochondrial hyperpolarization and ATP generation. These FFA also decreased Akt activation by insulin. As opposed to saturated FFA, unsaturated FFA did not impair glucose metabolism and mitochondrial function. Primary cultures of rat skeletal muscle cells exhibited similar responses to saturated FFA as compared to C2C12 cells. These results show that in muscle cells saturated FFA-induced mitochondrial dysfunction associated with impaired insulin-induced glucose metabolism. J. Cell. Physiol. 222: 187-194, 2010. (C) 2009 Wiley-Liss, Inc.

PAR(2) and Temporomandibular Joint Inflammation in the Rat

The proteinase-activated receptor 2 (PAR(2)) is a putative therapeutic target for arthritis. We hypothesized that the early pro-inflammatory effects secondary to its activation in the temporomandibular joint (TMJ) are mediated by neurogenic mechanisms. Immunofluorescence analysis revealed a high degree of neurons expressing PAR(2) in retrogradely labeled trigeminal ganglion neurons. Furthermore, PAR(2) immunoreactivity was observed in the lining layer of the TMJ, co-localizing with the neuronal marker PGP9.5 and substance-P-containing peripheral sensory nerve fibers. The intra-articular injection of PAR(2) agonists into the TMJ triggered a dose-dependent increase in plasma extravasation, neutrophil influx, and induction of mechanical allodynia. The pharmacological blockade of natural killer 1 (NK(1)) receptors abolished PAR(2)-induced plasma extravasation and inhibited neutrophil influx and mechanical allodynia. We conclude that PAR(2) activation is proinflammatory in the TMJ, through a neurogenic mechanism involving NK(1) receptors. This suggests that PAR(2) is an important component of innate neuro-immune response in the rat TMJ.

Upregulation of gp91(phox) Subunit of NAD(P)H Oxidase Contributes to Erectile Dysfunction Caused by Long-term Nitric Oxide Inhibition in Rats: Reversion by Regular Physical Training

OBJECTIVES To test the hypothesis that glyco protein 91phox (gp91(phox)) subunit of nicotinamide adenine dinucleotide phosphate [NAD(P) H] oxidase is a fundamental target for physical activity to ameliorate erectile dysfunction (ED). Vascular risk factors are reported to contribute to ED. Regular physical exercise prevents cardiovascular diseases by increasing nitric oxide (NO) production and/or decreasing NO inactivation. METHODS Male Wistar rats received the NO synthesis inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) for 4 weeks, after which animals were submitted to a run training program for another 4 weeks. Erectile functions were evaluated by in vitro cavernosal relaxations and intracavernous pressure measurements. Expressions of gp91(phox) subunit and neuronal nitric oxidase synthase in erectile tissue, as well as superoxide dismutase activity and nitrite/nitrate (NO(x)) levels were determined. RESULTS The in vitro acetylcholine-and electrical field stimulation-induced cavernosal relaxations, as well as the increases in intracavernous pressure were markedly reduced in sedentary rats treated with L-NAME. Run training significantly restored the impaired cavernosal relaxations. No alterations in the neuronal nitric oxidase synthase protein expression (and its variant penile neuronal nitric oxidase synthase) were detected. A reduction of NO(x) levels and superoxide dismutase activity was observed in L-NAME-treated animals, which was significantly reversed by physical training. Gene expression of subunit gp91(phox) was enhanced by approximately 2-fold in erectile tissue of L-NAME-treated rats, and that was restored to basal levels by run training. CONCLUSIONS Our study shows that ED seen after long-term L-NAME treatment is associated with gp91(phox) subunit upregulation and decreased NO bioavailability. Exercise training reverses the increased oxidative stress in NO-deficient rats, ameliorating the ED. UROLOGY 75: 961-967, 2010. (C) 2009 Elsevier Inc.

Putative antinociceptive action of nitric oxide in the caudal part of the spinal trigeminal nucleus during chronic carrageenan-induced arthritis in the rat temporomandibular joint

In order to investigate a putative role for nitric oxide (NO) in the central nociceptive processing following carrageenan-induced arthritis in the rat temporomandibular joint (TMJ), we analyzed the immunoreactivity, gene expression and activity of nitric oxide synthases (NOS) in the caudal part of the spinal trigeminal nucleus (Sp5C) during the acute (24 h), chronic (15 days) and chronic-active (14 days-24 h) arthritis. In addition, evaluation of head-withdrawal threshold was carried out in all phases of arthritis under chronic inhibition of nNOS with the selective inhibitor 7-nitroindazole (7-NI). Neurons with nNOS-like immunoreactivity (nNOS-LI) were concentrated mainly in the lamina II of the Sp5C, showing no significant statistical difference during arthritis. Only a discrete percentage of nNOS-LI neurons expressed Fos immunoreactivity. The mRNA expression for both nNOS and endothelial nitric oxide synthases (eNOS) presented no noticeable differences among the groups. No expression of inducible nitric oxide synthase (iNOS) was detected in the Sp5C by either immunohistochemistry or reverse-transcription polymerase chain reaction (RTPCR). Ca(2+)-dependent NOS activity in the ipsilateral Sp5C was significantly higher (108.3 +/- 49.2%; P<0.01) in animals during the chronic arthritis. Interestingly, this increased activity was completely abolished 24 h later, in the chronic-active arthritis. Finally, head-withdrawal threshold decreased significantly in the chronic arthritis in animals under 7-NI chronic inhibition. In conclusion, nNOS immunoreactivity and mRNA expression are stable in the Sp5C during TMJ arthritis evolution, but its activity significantly increases in the chronic-phases supporting an antinociceptive role of the nNOS as evidenced by pain threshold experiment. (C) 2009 Elsevier B.V. All rights reserved.

Participation of peripheral tachykinin NK(1) receptors in the carrageenan-induced inflammation of the rat temporomandibular joint

Temporomandibular disorders represent one of the major challenges in dentistry therapeutics. This study was undertaken to evaluate the time course of carrageenan-induced inflammation in the rat temporomandibular joint (TMJ) and to investigate the role of tachykinin NK(1) receptors. Inflammation was induced by a single intra-articular (i.art.) injection of carrageenan into the left TMJ (control group received sterile saline). Inflammatory parameters such as plasma extravasation, leukocyte influx and mechanical allodynia (measured as the head-withdrawal force threshold) and TNF alpha and IL-1 beta concentrations were measured in the TMJ lavages at selected time-points. The carrageenan-induced responses were also evaluated after treatment with the NK(1) receptor antagonist SR140333. The i.art. injection of carrageenan into the TMJ caused a time-dependent plasma extravasation associated with mechanical allodynia, and a marked neutrophil accumulation between 4 and 24 h. Treatment with SR140333 substantially inhibited the increase in plasma extravasation and leukocyte influx at 4 and 24 h, as well as the production of TNF alpha and IL-1 beta into the joint cavity, but failed to affect changes in head-withdrawal threshold. The results obtained from the present TMJ-arthritis model provide, for the first time, information regarding the time course of this experimental inflammatory process. In addition, our data show that peripheral NK(1) receptors mediate the production of both TNF alpha and IL-1 beta in the TMJ as well as some of the inflammatory signs, such as plasma extravasation and leukocyte influx, but not the nociceptive component. 2008 European Federation of Chapters of the International Association for the Study of Pain. Published by Elsevier Ltd. All rights reserved.

The allergic inflammatory reaction in neonatal streptozotocininduced diabetic rats: evidence of insulin resistance and microvascular dysfunction

To investigate the allergic reaction in neonatal streptozotocin (nSTZ)-induced diabetes mellitus. Male newborn Wistar rats were made diabetic by the injection of streptozotocin (160 mg/kg, i. p.) and used 8 weeks thereafter. Animals were sensitized against ovalbumin (OA, 50 mu g and Al(OH)3, 5 mg, s. c.) and challenged 14 or 21 days thereafter. OA-induced airway inflammation and OA-induced pleurisy models were used to investigate leukocyte migration (total and differential leukocyte counts) and lung vascular permeability (Evans blue dye extravasation). nSTZ-diabetic rats presented glucose intolerance and insulin resistance. Relative to controls, nSTZ rats exhibited a 30% to 50% reduction in lung vascular permeability. Leukocyte infiltration in both models of allergen-induced inflammation, and number of pleural mast cells did not differ between groups. Data suggest that the reduction of allergic inflammatory reactions in nSTZ rats is restricted to microvascular dysfunctions and associated, probably, with insulin resistance in lung microvascular endothelium.

Vimentin Expression and Myofibroblast Infiltration Are Early Markers of Renal Dysfunction in Kidney Transplantation: An Early Stage of Chronic Allograft Dysfunction?

Introduction. The objective of this study was to show the morphologic characteristics of allograft renal biopsies in renal transplant patients with stable renal function, which can potentially be early markers of allograft dysfunction, after 5 years of follow-up. Methods. Forty-nine renal transplant patients with stable renal function were submitted to renal biopsies and simultaneous measurement of serum creatinine (Cr). Histology was evaluated using Banff scores, determination of interstitial fibrosis by Sirius red staining and immunohistochemical study of proximal tubule and interstitial compartment (using cytokeratin, vimentin, and myofibroblasts as markers). Biopsies were evaluated according to the presence or absence of the epitheliomesenchymal transition (EMT). The interstitial presence of myofibroblasts and tubular presence of vimentin was also analyzed simultaneously. Renal function was measured over the follow-up period to estimate the reduction of graft function. Results. Median posttransplant time at enrollment was 105 days. Patients were followed for 64.3 +/- 8.5 months. The mean Cr at biopsy time was 1.44 +/- 0.33 mg/dL, and after the follow-up it was 1.29 +/- 0.27 mg/dL. Nine patients (19%) had a reduction of their graft function. Eleven biopsies (22%) had tubulointerstitial alterations according to Banff score. Seventeen biopsies (34%) presented EMT. Fifteen biopsies (32%) had high interstitial expression of myofibroblasts and tubular vimentin. Using Cox multivariate analysis, HLA and high expression of interstitial myofibroblasts and tubular vimentin were associated with reduction of graft function, yielding a risk of 3.3 (P = .033) and 9.8 (P = .015), respectively. Conclusion. Fibrogenesis mechanisms occur very early after transplantation and are risk factors for long-term renal function deterioration.

Increased Activation of Stromal Interaction Molecule-1/Orai-1 in Aorta From Hypertensive Rats A Novel Insight Into Vascular Dysfunction

Disturbances in the regulation of cytosolic calcium (Ca(2+)) concentration play a key role in the vascular dysfunction associated with arterial hypertension. Stromal interaction molecules (STIMs) and Orai proteins represent a novel mechanism to control store-operated Ca(2+) entry. Although STIMs act as Ca(2+) sensors for the intracellular Ca(2+) stores, Orai is the putative pore-forming component of Ca(2+) release-activated Ca(2+) channels at the plasma membrane. We hypothesized that augmented activation of Ca(2+) release-activated Ca(2+)/Orai-1, through enhanced activity of STIM-1, plays a role in increased basal tonus and vascular reactivity in hypertensive animals. Endothelium-denuded aortic rings from Wistar-Kyoto and stroke-prone spontaneously hypertensive rats were used to evaluate contractions because of Ca(2+) influx. Depletion of intracellular Ca(2+) stores, which induces Ca(2+) release-activated Ca(2+) activation, was performed by placing arteries in Ca(2+) free-EGTA buffer. The addition of the Ca(2+) regular buffer produced greater contractions in aortas from stroke-prone spontaneously hypertensive rats versus Wistar-Kyoto rats. Thapsigargin (10 mu mol/L), an inhibitor of the sarcoplasmic reticulum Ca(2+) ATPase, further increased these contractions, especially in stroke-prone spontaneously hypertensive rat aorta. Addition of the Ca(2+) release-activated Ca(2+) channel inhibitors 2-aminoethoxydiphenyl borate (100 mu mol/L) or gadolinium (100 mu mol/L), as well as neutralizing antibodies to STIM-1 or Orai-1, abolished thapsigargin-increased contraction and the differences in spontaneous tone between the groups. Expression of Orai-1 and STIM-1 proteins was increased in aorta from stroke-prone spontaneously hypertensive rats when compared with Wistar-Kyoto rats. These results support the hypothesis that both Orai-1 and STIM-1 contribute to abnormal vascular function in hypertension. Augmented activation of STIM-1/Orai-1 may represent the mechanism that leads to impaired control of intracellular Ca(2+) levels in hypertension. (Hypertension. 2009; 53[part 2]: 409-416.)

Coronary reserve impairment prevents the improvement of left ventricular dysfunction and adversely affects the long-term outcome of patients with hypertensive dilated cardiomyopathy

In hypertension, left ventricular (LV) hypertrophy develops as an adaptive mechanism to compensate for increased afterload and thus preserve systolic function. Associated structural changes such as microvascular disease might potentially interfere with this mechanism, producing pathological hypertrophy. A poorer outcome is expected to occur when LV function is put in jeopardy by impaired coronary reserve. The aim of this study was to evaluate the role of coronary reserve in the long-term outcome of patients with hypertensive dilated cardiomyopathy. Between 1996 and 2000, 45 patients, 30 of them male, with 52 +/- 11 years and LV fractional shortening <30% were enrolled and followed until 2006. Coronary flow velocity reserve was assessed by transesophageal Doppler of the left anterior descending coronary artery. Sixteen patients showed >= 10% improvement in LV fractional shortening after 17 +/- 6 months. Coronary reserve was the only variable independently related to this improvement. Total mortality was 38% in 10 years. The Cox model identified coronary reserve (hazard ratio = 0.814; 95% CI = 0.72-0.92), LV mass, low diastolic blood pressure, and male gender as independent predictors of mortality. In hypertensive dilated cardiomyopathy, coronary reserve impairment adversely affects survival, possibly by interfering with the improvement of LV dysfunction. J Am Soc Hypertens 2010;4(1):14-21. (C) 2010 American Society of Hypertension. All rights reserved.

trans, trans-2,4-decadienal induces mitochondrial dysfunction and oxidative stress

Lipid peroxidation produces a large number of reactive aldehydes as secondary products. We have previously shown that the reaction of cytochrome c with trans,trans-2, 4-decadienal (DDE), an aldehyde generated as a product of lipid peroxidation in cell membranes, results in the formation of adducts. Mass spectrometry analysis indicated that His-33, Lys-39, Lys-72 and Lys-100 in cytochrome c were modified by DDE. In the present work, we investigated the effect of DDE on isolated rat liver mitochondria. DDE (162 mu M) treatment increases the rate of mitochondrial oxygen consumption. Extensive mitochondrial swelling upon treatment with DDE (900 nM-162 mu M) was observed by light scattering and transmission electron microscopy experiments. DDE-induced loss of inner mitochondrial membrane potentials, monitored by safranin O fluorescence, was also observed. Furthermore, DDE-treated mitochondria showed an increase in lipid peroxidation, as monitored by MDA formation. These results suggest that reactive aldehydes promote mitochondrial dysfunction.

cis-4-decenoic acid provokes mitochondrial bioenergetic dysfunction in rat brain

Aims: In the present work we investigated the in vitro effect of cis-4-decenoic acid, the pathognomonic metabolite of medium-chain acyl-CoA dehydrogenase deficiency, on various parameters of bioenergetic homeostasis in rat brain mitochondria. Main methods: Respiratory parameters determined by oxygen consumption were evaluated, as well as membrane potential, NAD(P)H content, swelling and cytochrome c release in mitochondrial preparations from rat brain, using glutamate plus malate or succinate as substrates. The activities of citric acid cycle enzymes were also assessed. Key findings: cis-4-decenoic acid markedly increased state 4 respiration, whereas state 3 respiration and the respiratory control ratio were decreased. The ADP/O ratio, the mitochondrial membrane potential, the matrix NAD(P)H levels and aconitase activity were also diminished by cis-4-decenoic acid. These data indicate that this fatty acid acts as an uncoupler of oxidative phosphorylation and as a metabolic inhibitor. cis-4-decenoic acid also provoked a marked mitochondrial swelling when either KCl or sucrose was used in the incubation medium and also induced cytochrome c release from mitochondria, suggesting a non-selective permeabilization of the inner mitochondria! membrane. Significance: It is therefore presumed that impairment of mitochondrial homeostasis provoked by cis-4-decenoic acid may be involved in the brain dysfunction observed in medium-chain acyl-CoA dehydrogenase deficient patients. (C) 2010 Elsevier Inc. All rights reserved.