ANTI-OXIDANT EFFECTS OF ATORVASTATIN IN DEXAMETHASONE-INDUCED HYPERTENSION IN THE RAT

Combined Statin and Glucocorticoid Therapy for the Safer Treatment of Preterm Birth

BACKGROUND

Prematurity is strongly associated with poor respiratory function in the neonate. Rescue therapies include treatment with glucocorticoids due to their anti-inflammatory and maturational effects on the developing lung. However, glucocorticoid treatment in the infant can increase the risk of long-term cardiovascular complications including hypertension, cardiac, and endothelial dysfunction. Accumulating evidence implicates a molecular link between glucocorticoid excess and depletion of nitric oxide (NO) bioavailability as a mechanism underlying the detrimental effects of postnatal steroids on the heart and circulation. Therefore, combined glucocorticoid and statin therapy, by increasing NO bioavailability, may protect the developing cardiovascular system while maintaining beneficial effects on the lung.

METHODS

We investigated combined glucocorticoid and statin therapy using an established rodent model of prematurity and combined experiments of cardiovascular function in vivo, with those in isolated organs as well as measurements at the cellular and molecular levels.

RESULTS

We show that neonatal glucocorticoid treatment increases the risk of later cardiovascular dysfunction in the offspring. Underlying mechanisms include decreased circulating NO bioavailability, sympathetic hyper-reactivity, and NO-dependent endothelial dysfunction. Combined neonatal glucocorticoid and statin therapy protects the developing cardiovascular system by normalizing NO and sympathetic signaling, without affecting pulmonary maturational or anti-inflammatory effects of glucocorticoids.

CONCLUSIONS

Therefore, combined glucocorticoid and statin therapy may be safer than glucocorticoids alone for the treatment of preterm birth.

A systematic review and meta-analyses on the effects of atorvastatin on blood pressure and heart rate

AIMS

Considering the inconsistencies in the literature on the atorvastatin effect on blood pressure (BP), we performed these meta-analyses.

METHODS AND RESULTS

Through a search of the Excerpta Medica Database (EMBASE), PubMed, and Web of Science databases, 1412 articles were identified, from which 33 randomized clinical trials (RCT) and 44 pre-clinical were selected. Populations from RCT were stratified according to baseline BP and lipid levels. We performed meta-analyses of the effect of atorvastatin on systolic (SBP), diastolic and mean BP; heart rate (HR); HR variability, and baroreflex. Atorvastatin reduced SBP in the overall population (P = 0.05 vs. placebo; P = 0.03 vs. baseline), in normotensive and hyperlipidaemic (P = 0.04 vs. placebo; P = 0.0001 vs. baseline) and in hypertensive and hyperlipidaemic (P = 0.02 vs. placebo; P = 0.008 vs. baseline) individuals in parallel RCT, but it did not affect SBP in normotensive and normolipidaemic individuals (P = 0.51 vs. placebo; P = 0.4 vs. baseline). Although an effect of atorvastatin was detected in hyperlipidaemic individuals, the meta-regression coefficient for the association of low density lipoprotein (LDL)-cholesterol reduction with SBP reduction in the overall population demonstrated that SBP reduction is not dependent on the changes in LDL-cholesterol. A meta-analysis of preclinical reports demonstrated that SBP was reduced in atorvastatin-treated hypertensive and normolipidaemic rats (spontaneously hypertensive rats: P < 0.00001), but not in normotensive and normolipidaemic rats (control rats: P = 0.97). Atorvastatin also reduced the HR in spontaneously hypertensive rat.

CONCLUSION

Atorvastatin lowers BP independent of LDL-cholesterol levels. Additional studies are needed to estimate the involvement of the autonomic nervous system in the BP-lowering effect of atorvastatin.

Benefits of combined exercise training on arterial stiffness and blood pressure in spontaneously hypertensive rats treated or not with dexamethasone

Dexamethasone (DEX)-induced arterial stiffness is an important side-effect, associated with hypertension and future cardiovascular events, which can be counteracted by exercise training. The aim of this study was to evaluate the mechanisms induced by combined training to attenuate arterial stiffness and hypertension in spontaneously hypertensive rats treated or not with dexamethasone. Spontaneously hypertensive rats (SHR) underwent combined training for 74 days and were treated with dexamethasone (50 µg/kg s. c.) or saline solution during the last 14 days. Wistar rats were used as controls. Echocardiographic parameters, blood pressure (BP) and pulse wave velocity (PWV), as well as histological analyses of the heart and aorta, carotid and femoral arteries were performed. At the beginning, SHR had higher BP and PWV compared with Wistar rats. After 60 days, while BP increased in sedentary SHR, combined exercise training decreased BP and PWV. After 74d, the higher BP and PWV of sedentary SHR was accompanied by autonomic imbalance to the heart, cardiac remodeling, and higher arterial collagen deposition. DEX treatment did not change these parameters. On the other hand, trained SHR had reduced BP and PWV, which was associated with better autonomic balance to the heart, reduced myocardial collagen deposition, as well as lower arterial collagen deposition. The results of this study suggest that combined training, through the reduction of aortic collagen deposition, is an important strategy to reduce arterial stiffness in spontaneously hypertensive rats, and these lower responses were maintained regardless of dexamethasone treatment.

Differential effects of dexamethasone on arterial stiffness, myocardial remodeling and blood pressure between normotensive and spontaneously hypertensive rats

Dexamethasone (DEX)-induced hypertension is observed in normotensive rats, but little is known about the effects of DEX on spontaneously hypertensive animals (SHR). This study aimed to evaluate the effects of DEX on hemodynamics, cardiac hypertrophy and arterial stiffness in normotensive and hypertensive rats. Wistar rats and SHR were treated with DEX (50 μg/kg s.c., 14 d) or saline. Pulse wave velocity (PWV), echocardiographic parameters, blood pressure (BP), autonomic modulation and histological analyses of heart and thoracic aorta were performed. SHR had higher BP compared with Wistar, associated with autonomic unbalance to the heart. Echocardiographic changes in SHR (vs. Wistar) were suggestive of cardiac remodeling: higher relative wall thickness (RWT, +28%) and left ventricle mass index (LVMI, +26%) and lower left ventricle systolic diameter (LVSD, -19%) and LV diastolic diameter (LVDD, -10%), with slightly systolic dysfunction and preserved diastolic dysfunction. Also, SHR had lower myocardial capillary density and similar collagen deposition area. PWV was higher in SHR due to higher aortic collagen deposition. DEX-treated Wistar rats presented higher BP (~23%) and autonomic unbalance. DEX did not change cardiac structure in Wistar, but PWV (+21%) and aortic collagen deposition area (+21%) were higher compared with control. On the other side, DEX did not change BP or autonomic balance to the heart in SHR, but reduced RWT and LV collagen deposition area (-12% vs. SHR_CT ). In conclusion, the results suggest a differential effect of dexamethasone on arterial stiffness, myocardial remodeling and blood pressure between normotensive and spontaneously hypertensive rats.

Dexamethasone and Training-Induced Cardiac Remodeling Improve Cardiac Function and Arterial Pressure in Spontaneously Hypertensive Rats

INTRODUCTION

Dexamethasone (DEX)-induced hypertension and cardiac remodeling are still unclear, especially in spontaneously hypertensive rats (SHR). On the other side, exercise training is a good strategy to control hypertension. Therefore, this study investigated the effects of DEX treatment and physical training on arterial pressure and cardiac remodeling in SHR.

MATERIAL AND METHODS

SHR underwent treadmill training (5 days/week, 1h/session, at 50-60% of maximal capacity, 0% degree, 75 days) and received low-dose of DEX (50µg/kg, s.c.) during the last 15 days. Sedentary Wistar rats (W) were used as control. Echocardiography and artery catheterization were performed for cardiac remodeling and function, arterial pressure and autonomic nervous system analyses. In addition, left ventricle (LV) capillary density, myocyte diameter and collagen deposition area were analyzed using specific histological staining.

RESULTS

Low-dose of DEX treatment did not exacerbate arterial pressure of SHR and trained groups had lower values, regardless of DEX. DEX and training decreased relative left ventricle wall thickness (RWT) and determined LV angiogenesis (+19%) and lower collagen deposition area (-22%). In addition, it determined increased left ventricular diastolic diameter. These changes were followed by improvements on systolic and diastolic function, since it was observed increased posterior wall shortening velocity (PWSV) and reduced isovolumetric relaxation time (IVRT).

CONCLUSION

In conclusion, this study is unique to indicate that low-dose of DEX treatment does not exacerbate arterial pressure in SHR and, when associated with training, it improves LV systolic and diastolic function, which may be due to LV angiogenesis and reduction of wall collagen deposition area.

NOX-dependent reactive oxygen species production underlies arrhythmias susceptibility in dexamethasone-treated rats

Dexamethasone is the most clinically used glucocorticoid with an established role in the treatment of a wide spectrum of inflammatory-related diseases. While the therapeutic actions are well known, dexamethasone treatment causes a number of cardiovascular side effects, which are complex, frequent and, in some cases, clinically unnoticeable. Here, we investigated whether a therapeutic regimen of dexamethasone affects cardiac arrhythmogenesis, focusing on the contribution of Nox-derived reactive oxygen species (ROS). Male Wistar rats were treated with dexamethasone (2 mg/kg, i.p.) for 7 days. Afterward, hemodynamic measurements, autonomic modulation, left ventricular function, cardiac fibrosis, reactive oxygen species (ROS) generation, Nox protein expression, superoxide dismutase (SOD) and catalase activities, and arrhythmias incidence were evaluated. Here, we show that dexamethasone increases blood pressure, associated with enhanced cardiac and vascular sympathetic modulation. Moreover, a marked increase in the cardiac ROS generation was observed, whereas the enhanced SOD activity did not prevent the higher levels of lipid peroxidation in the dexamethasone group. On the other hand, increased cardiac Nox 4 expression and hydrogen peroxide decomposition rate was observed in dexamethasone-treated rats, while Nox 2 remained unchanged. Interestingly, although preserved ventricular contractility and β-adrenergic responsiveness, we found that dexamethasone-treated rats displayed greater interstitial and perivascular fibrosis than control. Surprisingly, despite the absence of arrhythmias at basal condition, we demonstrated, by in vivo and ex vivo approaches, that dexamethasone-treated rats are more susceptible to develop harmful forms of ventricular arrhythmias when challenged with pharmacological drugs or burst pacing-induced arrhythmias. Notably, concomitant treatment with apocynin, an inhibitor of NADPH oxidase, prevented these ectopic ventricular events. Together, our results reveal that hearts become arrhythmogenic during dexamethasone treatment, uncovering the pivotal role of ROS-generating NADPH oxidases for arrhythmias vulnerability.

MicroRNA-126 upregulation, induced by training, plays a role in controlling microcirculation in dexamethasone treated rats

Microcirculation maintenance is associated with microRNAs. Nevertheless, the role of microRNAs induced by training in preventing dexamethasone (DEX)-induced microvascular rarefaction remains unknown. The study aim was to investigate if training-induced microRNAs are able to improve microcirculation proteins and prevent DEX-induced microvascular rarefaction. Rats underwent training for 8 weeks and then were treated with DEX (50 μg/kg per day, s.c.) for 14 days. Arterial pressure was measured and tibialis anterior (TA) muscle was collected for analyses. DEX induced hypertension concomitantly with capillary density loss (CD, -23.9%) and decrease of VEGF (-43.0%), p-AKT/AKT (-39.6%) and Bcl-2 (-23.0%) and an increase in caspase-3-cleaved protein level (+34.0%) in TA muscle. Training upregulated microRNA-126 expression (+13.1%), prevented VEGF (+61.4%), p-AKT/AKT (+37.7%), Bcl-2 (+7.7%) decrease and caspase-3-cleaved (-23.1%) increase associated with CD (+54.7%) reduction and hypertension prevention. MiRNA-126 upregulation, induced by training, plays a role in controlling microcirculation, which may be a potential target against DEX-induced microvascular rarefaction.

Training counteracts DEX-induced microvascular rarefaction by improving the balance between apoptotic and angiogenic proteins

This work investigated the mechanisms induced by exercise training that may contribute to attenuate dexamethasone (DEX)-induced microvascular rarefaction and hypertension. Wistar rats underwent training protocol or were kept sedentary for 8 weeks. Dexamethasone was administered during the following 14-days and hemodynamic parameters were recorded at the end. Capillary density (CD) and capillary-to-fiber ratio (C:F ratio) were obtained in soleus muscle (SOL). Also, vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor-2 (VEGFR-2), endothelial nitric oxide synthase (eNOS), B-cell lymphoma 2 (Bcl-2), Bcl-2-like protein 4 (Bax), p-BAX and caspase-3 cleaved protein levels were analyzed. DEX treatment significantly increased blood pressure (+14%), which was associated with reduced C:F ratio (-41.0%) and CD (-43.1%). Reduction of vessel density was associated with decreased VEGF (-15.6%), VEGFR-2 (-14.6%), Bcl-2 (-18.4%), Bcl-2/Bax ratio (-29.0%) and p-Bax/Bax (-25.4%), and also with increased caspase-3 cleaved protein level (25%). Training, on the other hand, prevented microvessels loss by mitigating all proteins changes induced by DEX. In addition, angiogenic and apoptotic proteins were significantly correlated with CD, which, in turn, was associated with blood pressure. Therefore, we may point out that exercise training is a good strategy to attenuate DEX-induced microvascular rarefaction in soleus muscle and this response involves a better balance between apoptotic and angiogenic proteins, which may contribute for the attenuation of hypertension.

Dexamethasone Causes Hypertension in Rats Even Under Chemical Blockade of Peripheral Sympathetic Nerves

Synthetic glucocorticoids (GCs) are widely used to treat inflammatory conditions. However, chronic use of GCs can lead to hypertension. The cause of this undesired side effect remains unclear. Previously, we developed an in vivo rat model to study the mechanisms underlying hypertension induced by the chronic administration of the potent synthetic GC, dexamethasone (DEX) and found that the catecholamine biosynthetic pathway plays an important role. In the current study, we used this model to investigate the role of the adrenal medulla, renal nerves, and other peripheral sympathetic nerves in DEX-induced hypertension. After 5 days of baseline telemetric recording of mean arterial pressure (MAP) and heart rate (HR), rats were subjected to one of the following treatments: renal denervation (RDNX), adrenal medullectomy (ADMX), 6-hydroxydopamine (6-OHDA, 20 mg/kg, i.p.) to induce chemical sympathectomy, or a combination of ADMX and 6-OHDA. On day 11, the animals received vehicle (VEH) or DEX in drinking water for 7 days, with the latter causing an increase in MAP in control animals. ADMX and RDNX by themselves exacerbated the pressor effect of DEX. In the chemical sympathectomy group, DEX still caused a rise in MAP but the response was lower (ΔMAP of 6-OHDA/DEX < VEH/DEX, p = 0.039). However, when ΔMAP was normalized to day 10, 6-OHDA + DEX did not show any difference from VEH + DEX, certainly not an increase as observed in DEX + ADMX or RDNX groups. This indicates that sympathetic nerves do not modulate the pressor effect of DEX. TH mRNA levels increased in the adrenal medulla in both VEH/DEX (p = 0.009) and 6-OHDA/DEX (p = 0.031) groups. In the 6-OHDA group, DEX also increased plasma levels of norepinephrine (NE) (p = 0.016). Our results suggest that the activation of catecholamine synthetic pathway could be involved in the pressor response to DEX in animals even under chemical sympathectomy with 6-OHDA.

Augmentation of autophagy by atorvastatin via Akt/mTOR pathway in spontaneously hypertensive rats

Autophagy is activated in hypertension-induced cardiac hypertrophy. However, the mechanisms and significance of an activated autophagy are not clear. This study was designed to determine the role of atorvastatin (ATO) in cardiac autophagy and associated benefits on cardiac remodeling and left ventricular function in spontaneously hypertensive rats (SHRs). Twenty-eight male SHRs at 8 weeks of age were randomized to treatment with vehicle (saline solution; SHR+V) or ATO (SHR+ATO; 50 mg kg(-1) per day) for 6 or 12 months. Age-matched male Wistar-Kyoto (WKY) rats were used as normotensive controls. Cardiac magnetic resonance was used to evaluate cardiac function and structure. Compared with WKY rats, SHRs showed significant left ventricle (LV) dysfunction, remodeling and increases in cardiomyocyte size, which were all attenuated by 6 and 12 months of ATO treatment. Compared with WKY rats, autophagy was activated in the hearts of SHRs and this effect was amplified by chronic ATO treatment, particularly following 12 months of treatment. Protein expression levels of microtubule-associated protein-1 light chain 3-II and beclin-1, the biomarkers of an activated cardiac autophagy, were significantly elevated in ATO-treated versus vehicle-treated SHRs and control WKY rats. Cardiac Akt and phosphorylated mammalian target of rapamycin (mTOR) expression were also increased in the hearts of SHR versus WKY rats, and this effect was attenuated by ATO treatment. These findings suggest that ATO-mediated improvements in LV function and structure in SHRs may be, in part, through its regulation of cardiac autophagy via the Akt/mTOR pathway.

Effect of statins on preventing infectious complications after surgery: Systematic review and meta-analysis

OBJECTIVE

*These authors contributed equally to this work.A meta-analysis to investigate the association between preoperative statin use and the risk of postoperative infectious complications in patients undergoing surgery.

METHODS

PubMed(®) and Embase(®) databases were searched for relevant studies. Data were extracted using a standardized data collection form. The primary effect measure was the odds ratio (OR) of postoperative infectious complications. Summary OR were calculated.

RESULTS

The analysis included 10 cohort studies with a total of 147 263 participants. Statin use was associated with a lower incidence of postoperative infectious complications in all studies (summary OR 0.917, 95% confidence intervals [CI] 0.862, 0.975, fixed-effects model; summary OR 0.731, 95% CI 0.584, 0.870, random-effects model); cardiac surgery (summary OR 0.673; 95% CI 0.535, 0.847); treatment in the USA (summary OR 0.678; 95% CI 0.597, 0.770); retrospective cohort studies (summary OR 0.664; 95% CI 0.521, 0.846).

CONCLUSION

Preoperative statin use is associated with a reduced risk of postoperative infectious complications.

Antioxidant effects of bovine lactoferrin on dexamethasone-induced hypertension in rat

Dexamethasone- (Dex-) induced hypertension is associated with enhanced oxidative stress. Lactoferrin (LF) is an iron-binding glycoprotein with antihypertensive properties. In this study, we investigated the effect of chronic administration of LF on oxidative stress and hypertension upon Dex administration. Male Wistar rats were treated by Dex (30 μg/kg/day subcutaneously) or saline for 14 days. Oral bovine LF (30, 100, 300 mg/kg) was given from day 8 to 14 in a reversal study. In a prevention study, rats received 4 days of LF treatment followed by Dex and continued during the test period. Systolic blood pressure (SBP) was measured using tail-cuff method. Thymus weight was used as a marker of glucocorticoid activity. Plasma hydrogen peroxide (H₂O₂) concentration and ferric reducing antioxidant power (FRAP) value were determined. Dexamethasone significantly increased SBP and plasma H₂O₂ level and decreased thymus and body weights. LF lowered (P < 0.01) and dose dependently prevented (P < 0.001) Dex-induced hypertension. LF prevented body weight loss and significantly reduced the elevated plasma H₂O₂ and increased FRAP values. Chronic administration of LF strongly reduced the blood pressure and production of ROS and improved antioxidant capacity in Dex-induced hypertension, suggesting the role of inhibition of oxidative stress as another mechanism of antihypertensive action of LF.

Statins prevent adverse effects of postnatal glucocorticoid therapy on the developing brain in rats

BACKGROUND

Postnatal glucocorticoid therapy in the treatment of chronic lung disease benefits lung function, however it adversely affects brain development. We hypothesized that combined postnatal glucocorticoid and statin therapy diminishes adverse effects of glucocorticoids on the developing brain.

METHODS

On postnatal days (P) 1-3, one male pup per litter received i.p. injections of saline control (C), n = 13) or dexamethasone (0.5, 0.3, 0.1 µg/g; D, n = 13), ± pravastatin (10 mg/kg i.p.; CP, n = 12; DP, n = 15). Statins or saline continued from P4-6. At P21, brains were perfusion fixed for histological and stereological analyses.

RESULTS

Relative to controls, dexamethasone reduced total (837 ± 23 vs. 723 ± 37), cortical (378 ± 12 vs. 329 ± 15), and deep gray matter (329 ± 12 vs. 284 ± 15) volume (mm(3)), cortical neuronal number (23 ± 1 vs. 19 ± 1 × 10(6)), and hippocampal neuronal soma volume (CA1: 1,206 ± 32 vs. 999 ± 32; dentate gyrus: 679 ± 28 vs. 542 ± 24 µm(3); all P < 0.05). Dexamethasone increased the glial fibrillary acidic protein-positive astrocyte density in the white matter (96 ± 2 vs. 110 ± 4/0.1 mm(2)); P < 0.05. These effects no longer occurred in brains from pups treated with combined dexamethasone and pravastatin. Pravastatin alone had no effect on these variables.

CONCLUSION

Concomitant dexamethasone with statins in premature infants may be safer for the developing brain than dexamethasone alone in the treatment of chronic lung disease.

Antioxidant treatment improves neonatal survival and prevents impaired cardiac function at adulthood following neonatal glucocorticoid therapy

Glucocorticoids are widely used to treat chronic lung disease in premature infants but their longer-term adverse effects on the cardiovascular system raise concerns. We reported that neonatal dexamethasone treatment in rats induced in the short term molecular indices of cardiac oxidative stress and cardiovascular tissue remodelling at weaning, and that neonatal combined antioxidant and dexamethasone treatment was protective at this time. In this study, we investigated whether such effects of neonatal dexamethasone have adverse consequences for NO bioavailability and cardiovascular function at adulthood, and whether neonatal combined antioxidant and dexamethasone treatment is protective in the adult. Newborn rat pups received daily i.p. injections of a human-relevant tapering dose of dexamethasone (D; n = 8; 0.5, 0.3, 0.1 μg g(-1)) or D with vitamins C and E (DCE; n = 8; 200 and 100 mg kg(-1), respectively) on postnatal days 1-3 (P1-3); vitamins were continued from P4 to P6. Controls received equal volumes of vehicle from P1 to P6 (C; n = 8). A fourth group received vitamins alone (CCE; n = 8). At P100, plasma NO metabolites (NOx) was measured and isolated hearts were assessed under both Working and Langendorff preparations. Relative to controls, neonatal dexamethasone therapy increased mortality by 18% (P < 0.05). Surviving D pups at adulthood had lower plasma NOx concentrations (10.6 ± 0.8 vs. 28.0 ± 1.5 μM), an increased relative left ventricular (LV) mass (70 ± 2 vs. 63 ± 1%), enhanced LV end-diastolic pressure (14 ± 2 vs. 8 ± 1 mmHg) and these hearts failed to adapt output with increased preload (cardiac output: 2.9 ± 2.0 vs. 10.6 ± 1.2 ml min(-1)) or afterload (cardiac output: -5.3 ± 2.0 vs.1.4 ± 1.2 ml min(-1)); all P < 0.05. Combined neonatal dexamethasone with antioxidant vitamins improved postnatal survival, restored plasma NOx and protected against cardiac dysfunction at adulthood. In conclusion, neonatal dexamethasone therapy promotes cardiac dysfunction at adulthood. Combined neonatal treatment with antioxidant vitamins is an effective intervention.

Glucocorticoid-induced hypertension and the nitric oxide system

Glucocorticoid hormones, both naturally occurring and synthetic, have long been recognized as a major cause of hypertension. There are well-described experimental models of glucocorticoid-induced hypertension, such as adrenocorticotropic hormone- and dexamethasone-induced hypertension in rats, although the exact mechanism of glucocorticoid-induced hypertension remains unclear. It was initially considered to be due to mineralocorticoid receptor activation but more recent studies have not supported this notion. Current evidence demonstrates the importance of the nitric oxide (NO) system and interactions between NO and reactive oxygen species in the development of glucocorticoid-induced hypertension. This review highlights the pathways contributing to NO deficiency, which encompass the availability of l-arginine, endothelial NO synthase function and the extent of NO inactivation during oxidative stress.

Statin treatment depresses the fetal defence to acute hypoxia via increasing nitric oxide bioavailability

In addition to lowering cholesterol, statins increase nitric oxide (NO) bioavailability, improving endothelial function. In the fetus, enhanced NO during acute hypoxia opposes the fetal peripheral vasoconstrictor response, part of the brain-sparing defence. This study tested the hypothesis that treatment with statins depresses the fetal circulatory response to acute hypoxic stress via increasing NO bioavailability. Under anaesthesia, 12 fetal sheep at 118 ± 1 days of gestation (term ca 145 days) were instrumented with vascular catheters and a femoral artery Transonic flow probe for chronic recording. Five days later, all animals were subjected to 30 min of acute hypoxia (fetal arterial partial pressure of O(2) ( ) reduced by ca 50%) before and 24 h after fetal treatment with pravastatin (25 mg i.v.). In half of the fetuses (n = 6), responses to hypoxia post-pravastatin were evaluated during NO synthesis blockade. Fetal exposure to pravastatin did not affect fetal basal cardiovascular function. Fetal was similarly reduced in all acute hypoxia experiments from ca 21 to 10 mmHg. Fetal exposure to pravastatin markedly diminished the fetal femoral vasoconstrictor (5.1 ± 0.9 vs. 2.5 ± 0.5 mmHg (ml min(-1))(-1)) and lactic acidaemic (4.4 ± 0.5 vs. 3.0 ± 0.3 mm) responses to acute hypoxia (both P < 0.05), without affecting plasma catecholamine responses. Post-pravastatin, the circulatory (5.8 ± 1.5 mmHg (ml min(-1))(-1)) and metabolic (3.9 ± 0.3 mm) responses could be restored to control levels during fetal treatment with NO synthase blockade. Pravastatin depresses the fetal cardiovascular and metabolic defences to acute hypoxia via increasing NO bioavailability. The use of statins during pregnancy should be viewed with extreme caution.

How mental stress affects endothelial function

Mental stress is an important factor contributing to recognized mechanisms underlying cardiovascular events. Among these, stress-related endothelial dysfunction is an early risk factor that predicts future development of severe cardiovascular disorders. Acute mental stress by a variety of tests impairs endothelial function in humans, although the opposite results have been reported by some investigators. Chronic stress always deteriorates endothelial function in humans and experimental animals. Stress hormones, such as glucocorticoids and pro-inflammatory cytokines, and endothelin-1 liberated in response to mental stress participate in endothelial dysfunction possibly via downregulation of endothelial nitric oxide synthase (eNOS) expression, eNOS inactivation, decreased nitric oxide (NO) actions, and increased NO degradation, together with vasoconstriction counteracting against NO-induced vasodilatation. Catecholamines do not directly affect endothelial function but impair its function when blood pressure elevation by the amines is sustained. Endogenous opioids favorably affect endothelial function, which counteract deteriorating effects of other stress hormones and mediators. Inhibition of cortisol and endothelin-1 production, prevention of pro-inflammatory mediator accumulation, hypnotics, mirthful laughter, humor orientation, and lifestyle modification would contribute to the prevention and treatment for stress-related endothelial dysfunction and future serious cardiovascular disease.

How do glucocorticoids cause hypertension: role of nitric oxide deficiency, oxidative stress, and eicosanoids

The exact mechanism by which glucocorticoid induces hypertension is unclear. Several mechanisms have been proposed, although there is evidence against the role of sodium and water retention as well as sympathetic nerve activation. This review highlights the role of nitric oxide-redox imbalance and their interactions with arachidonic acid metabolism in glucocorticoid-induced hypertension in humans and experimental animal models.

Study of Atorvastatin in experimental allergic airway inflammation in mice

BACKGROUND

Inflammation and oxidative stress are associated with airway diseases. There is growing evidence that Atorvastatin could be used as a therapy for these conditions.

OBJECTIVE

On these bases, we evaluated Atorvastatin as a protective and reversal treatment for the allergic airway diseases in mice model. We also looked at the possible interaction with the currently used effective medication.

METHODS

Mice were sensitized and challenged with ovalbumin (OVA) to develop features of allergic airway diseases mainly of bronchial inflammation. Atorvastatin was injected during or after the sensitization and challenge process to evaluate its protective or reversal effects, respectively. Total and differential cells in the BAL fluids together with IL-4, IL-5 and IL-10 cytokine levels were evaluated. Total IgE and cholesterol levels in serum were studied.

RESULTS

In the protective phase, Atorvastatin inhibited the OVA-induced cellular infiltration of lung bronchi, decreased IL-4 and IL-5 and prevented the increase in IL-10 cytokine levels. Also, it reduced the OVA-induced high serum total IgE level. Injection of Atorvastatin after challenge was not effective in reversing the inflammatory process, with no major contribution towards augmenting the actions of Dexamethasone. The cholesterol lowering effect was marked in the protective phase while less effective for the reversal phase.

CONCLUSION

Our results indicate that Atorvastatin reduced the allergic inflammatory features in mice and it could be useful towards developing a better therapeutic regimen for the treatment of allergic diseases.

Chronic antioxidant therapy fails to ameliorate hypertension: potential mechanisms behind

Hypertension in association with oxidative stress belongs to the most discussed topics within the literature on cardiovascular diseases. It is generally believed that elevated production of reactive oxygen species (ROS) plays an important role in hypertension, but clinical studies on chronic antioxidant therapy of hypertension fail to confirm this hypothesis. This discrepancy may be partly determined by the different effects of short and long-lasting treatment with antioxidants or scavengers. Elevated ROS production in hypertension need not be only harmful. It may also stimulate the activity of the antioxidant defence system and improve the nitric oxide (NO)/cyclic 3', 5'-guanosine monophosphate pathway, resulting in the establishment of a new equilibrium between enhanced oxidative load and the stimulated NO pathway, thus maintaining sufficient NO bioavailability. It has been suggested that antioxidant treatment might be beneficial for a short time, until increased NO generation predominates over ROS production. Further weakening of ROS formation by antioxidants may attenuate nuclear factor kappa B activation resulting in decreased endothelial NO synthase expression and activity. Prolonged antioxidant therapy may thus attenuate the beneficial regulatory effect of ROS, leading to decreased NO generation and the re-establishment of the undesirable disproportion between deleterious and protective forces. As a consequence prolonged antioxidant treatment in human hypertension may fail to provide the expected clinical profit.