Oxidative Stress Induced by 30 Days of Mercury Exposure Accelerates Hypertension Development in Prehypertensive Young SHRs.

Mercury is considered a risk factor for the development of hypertension and other cardiovascular diseases. We investigated whether the effects of mercury exposure on haemodynamic parameters of young Wistar rats and prehypertensive SHRs might alter the time course of hypertension development. Young (4 weeks) male Wistar rats and SHRs were randomly assigned to four groups: untreated Wistar rats (Wistar Ct), Wistar rats exposed to mercury chloride for 30 days (Wistar Hg), untreated SHRs (SHR Ct) and SHRs exposed to mercury chloride (SHR Hg) for 30 days. Non-invasive and invasive arterial pressures were measured to investigate pressure reactivity; nitrite/nitrate levels, ACE activity, and lipid peroxidation were measured in plasma. The systolic blood pressure (SBP) of the Wistar rat groups did not change but increased in the SHRs from the second week to the last week. Hg exposure accelerated the increase in the SBP of SHRs. L-NAME administration increased SBP and diastolic blood pressure (DBP) in all groups, but this increase was smaller in SHRs exposed to Hg. A decrease in plasma nitrite and nitrate levels in the SHR Hg group suggested that mercury reduced NO bioavailability. Tempol-reduced blood pressure suggesting that the superoxide anion played a role in the marked increase in this parameter. These findings provide evidence that Hg exposure might activate mechanisms to accelerate hypertension development, including a reduction in NO bioavailability. Therefore, predisposed individuals under mercury exposure are at greater risk from an enhanced development of hypertension.

Physiological and Biochemical Vascular Reactivity Parameters of Angiotensin II and the Action of Biased Agonist TRV023.

Vascular reactivity experiments using isolated aortic rings have been widely used as a model for physiological and pharmacological studies since the early sixties. Here, we suggest several parameters that the researcher should pay attention to when investigating angiotensin II in their experimental models. Angiotensin II is one of the active peptides of the renin-angiotensin system and exerts its effect through the AT1 and AT2 receptors. Some studies seek to understand the effects of angiotensin II receptors at the vascular level by using vascular reactivity experiments. However, because of the large number of variations, there are only a handful of reactivity studies that seek to use this method. Thus, the objective of this study was to standardize experimental methods with angiotensin II, through vascular reactivity protocols. For this, variables such as basal tension, concentration interval, single concentration, curve concentration response, and multiple experiments using the same aortic ring were developed using the technique of vascular reactivity in an organ bath. This is the first study that has standardized the vascular reactivity protocol. In addition, we demonstrated the effects of TRV023-biased ligand of the AT1R at vascular sites.

Chronic iron overload intensifies atherosclerosis in apolipoprotein E deficient mice: Role of oxidative stress and endothelial dysfunction.

AIMS: We previously demonstrated that iron overload induces endothelial dysfunction and oxidative stress, which could increase the risk for atherosclerosis. However, the iron-related harmfulness under a genetic predisposition to atherosclerosis is still unclear. Here, we have tested the hypothesis that chronic iron overload may change vascular reactivity associated with worsening of the atherosclerotic process in apolipoprotein E knockout (apoE(-/-)) mice. MAIN METHODS: Serum and aortas of wild-type (WT) and apoE(-/-) mice injected with iron-dextran (IO, 10 mg/mouse/day, ip) or saline 5 times a week for 4 weeks, were used. KEY FINDINGS: Iron overload increased serum levels of iron and biomarkers of liver injury and oxidative stress, and iron deposition in the aorta in both lines, but only apoE(-/-) IO mice had intensified hypercholesterolemia and atherosclerosis. By scanning electron microscopy, the small endothelial structural damage caused by iron in WT was worsened in the apoE(-/-) group. However, endothelial dysfunction was found only in the apoE(-/-) IO group, identified by impaired relaxation to acetylcholine and hyperreactivity to phenylephrine associated with reduced nitric oxide modulation. Moreover, tiron and indomethacin attenuated reactivity to phenylephrine with greater magnitude in aortas of the apoE(-/-) IO group. Confirming, there were changes in the antioxidant (superoxide dismutase and catalase) activity, increased expression of cyclooxygenase-2 in the aorta and elevated levels of thromboxane A2 and prostacyclin metabolites in the urine of apoE(-/-) IO. SIGNIFICANCE: Our results showed that chronic iron overload intensifies the atherosclerotic process and induces endothelial dysfunction in atherosclerotic mice, probably due to the oxidative stress and the imbalance between the relaxing and contractile factors synthesized by the damaged endothelium.

Effects of direct high sodium exposure at endothelial cell migration.

The present study aimed to test the hypothesis that high sodium affects the migratory phenotype of endothelial cells (EC) and investigates mechanisms involved independently of hemodynamic factors. Cell migration was evaluated by Wound-Healing at conditions: High Sodium (HS; 160 mM) and Control (CT; 140 mM). O2- production was evaluated by DHE. NADPH oxidase activity was determined by chemiluminescence assay. Expression of adhesion molecules was analyzed by RT-PCR. Shear Stress was performed using a rhythmic shake. Nitric oxide production was measured by Griess reaction. HS-induced impairment in EC migration while both Candesartan and DPI prevented it. HS increased NADPH oxidase activity, which was blocked by Candesartan. Also, HS increased O2- production that was inhibited by Candesartan. HS decreased adhesion molecules expression via ROS (Integrin Alpha 5, Integrin Beta 1, Integrin Beta 3, VE-Cadherin and PECAM) and via AT1R (PECAM). The nitric oxide production induced by shear stress was decreased after EC exposure to HS while both Candesartan and DPI prevented it. Conclusion: This study demonstrated that HS reduced EC migration by AT1R and ROS derived from NADPH Oxidase and mitochondria. The HS reduction in adhesion molecules expression modulated by ROS and AT1R may help to explain the impairment in migration capacity. Also, HS affected EC functionality by reducing their nitric oxide production in response to shear stress.

In vivo antimutagenic and antiatherogenic effects of the (1 → 3)(1 → 6)-ß-d- glucan botryosphaeran.

The antimutagenic effect of botryosphaeran, an exocellular (1 → 3)(1 → 6)-ß-d-glucan, from the ascomyceteous and plant-borne endophytic fungus, Botryosphaeria rhodina MAMB-05, was evaluated in young (6-8 weeks) and elderly (18 months) Swiss albino mice of both genders. The hypolipidemic, hypoglycemic and antiatherogenic potential was also evaluated in 18-month old male LDL receptor knockout (LDLr-/-) mice. Administration of botryosphaeran by gavage (doses: 7.5, 15, 30 mg/kg b.w./day) in a 30-day pretreatment protocol (young mice), or 15-day protocol (older mice), did not cause genotoxicity as assessed by the micronucleus test in peripheral blood (PB) and bone marrow cells (BMCs). Furthermore, there was no cytotoxic effect of this ß-d-glucan in the treatments. A lower frequency of micronuclei was observed in BMCs from young and old mice that received botryosphaeran, indicating its antimutagenic effect. Botryosphaeran (30 mg/kg b.w./day) promoted 102.22% (young) and 103.45% (elderly) reductions in cyclophosphamide-induced damage in male mice. Botryosphaeran also exerted chemoprotective effects in LDLr-/- and wild-type (C57BL/6) mice. Botryosphaeran treatment for 15 days at a dose of 30 mg/kg b.w./day improved the lipidic profile (reductions of 53.8-84.3%), and decreased aortic lipid deposition (32.8%) in the LDLr-/- atherosclerotic mice. The results indicate botryosphaeran has relevant biologic effects, making it a promising candidate for the development of new therapeutic agents.

Effects of controlled doses of Oxyelite Pro on physical performance in rats.

BACKGROUND: OxyElite Pro (OEP) is a dietary supplement to increase metabolism which contains as key stimulant the ingredient 1,3-dimethylamylamine (DMAA). Serious adverse effects have been reported after OEP consumption however, these effects are related to poisoning or overdose. To our knowledge, no one studied the effects of OEP at controlled doses. Thus, the aim of this study was to evaluate acute and chronic OEP affects, at controlled doses in Wistar rats, on physical performance, metabolic parameters, liver injury markers and oxidative stress markers and mitochondrial biogenesis in skeletal muscle. METHODS: Rats were divided in control, 4.3 mg OEP/kg, 12.9 mg OEP/kg and 25.8 mg OEP/kg. All groups were submitted to supplementation with OEP for 4 weeks and the experimental protocols were performed 30 min after the first OEP administration (acute response) and 30 min after the last OEP administration at the end of the forth week (chronic response). RESULTS: Running distance and running time increased after acute administration of 12.9 mg OEP/kg (2.6-fold) and 25.8 mg OEP/kg (2.8-fold). Since no effect on the exercise tolerance test was observed at the lower OEP dose (4.3 mg OEP/kg), this group was removed from further analyzes. On other hand, running distance and running time decreased after daily supplementation for 4 weeks also in both groups (64% in 12.9 mg OEP/kg and 72% in 25.8 mg OEP/kg). Chronic supplementation at both 12.9 and 25.8 mg OEP/kg decreased TBARS levels in soleus muscle (36 and 31%) and liver (43 and 25%). AOPP was also decreased by both doses in the liver (39 and 45%). Chronic administration of the highest dose, 25.8 mg OEP/kg, was able to reduce mRNA expression of PGC-1α in soleus muscle (25%). No effect was found in other analyses such as spontaneous physical activity, body weight, food and water intake, hepatic toxicity, cardiac oxidative stress and mitochondrial DNA amount. CONCLUSION: Maximum and not recommended doses of OEP ingested acutely presented stimulating effect on the ability to exercise. However, its daily consumption for 4 weeks showed antioxidant effects in soleus muscle and liver which may have decreased the PGC-1α mRNA expression on soleus muscle and contributed to the impaired performance in the exercise tolerance test.