Chronic stress, but not hypercaloric diet, impairs vascular function in rats

Τhe neuroprotective role of environmental enrichment against behavioral, morphological, neuroendocrine and molecular changes following chronic unpredictable mild stress: A systematic review

Environmental factors interact with biological and genetic factors influencing the development and well-being of an organism. The interest in better understanding the role of environment on behavior and physiology led to the development of animal models of environmental manipulations. Environmental enrichment (EE), an environmental condition that allows cognitive and sensory stimulation as well as social interaction, improves cognitive function, reduces anxiety and depressive-like behavior and promotes neuroplasticity. In addition, it exerts protection against neurodegenerative disorders, cognitive aging and deficits aggravated by stressful experiences. Given the beneficial effects of EE on the brain and behavior, preclinical studies have focused on its protective role as an alternative, non-invasive manipulation, to help an organism to cope better with stress. A valid, reliable and effective animal model of chronic stress that enhances anxiety and depression-like behavior is the chronic unpredictable mild stress (CUMS). The variety of stressors and the unpredictability in the time and sequence of exposure to prevent habituation, render CUMS an ethologically relevant model. CUMS has been associated with dysregulation of the hypothalamic-pituitary-adrenal axis, elevation in the basal levels of stress hormones, reduction in brain volume, dendritic atrophy and alterations in markers of synaptic plasticity. Although numerous studies have underlined the compensatory role of EE against the negative effects of various chronic stress regimens (e.g. restraint and social isolation), research concerning the interaction between EE and CUMS is sparse. The purpose of the current systematic review is to present up-to-date research findings regarding the protective role of EE against the negative effects of CUMS.

Resveratrol improves vascular endothelial dysfunction in the unpredictable chronic mild stress model of depression in rats by reducing inflammation

Chronic psychological stress may cause depression and it is a risk factor for vascular endothelial dysfunction. Inflammation may contribute to endothelial dysfunction. Resveratrol, which has antiinflammatory and vasculoprotective properties, has been reported its beneficial effects on endothelial dysfunction induced by hypertension, diabetes and, aging. The effects of resveratrol on stress-induced endothelial dysfunction is not investigated yet. This study aimed to investigate the efficacy of resveratrol on vascular function in the unpredictable chronic moderate stress (UCMS) model of rats and to examine the possible mechanisms of resveratrol by assessment of proinflammatory markers. Male rats were assigned to 4 groups (n = 8 for each group): Control, Control+Resveratrol, UCMS, UCMS+Resveratrol. UCMS and UCMS+Resveratrol groups were exposed to the UCMS procedure for 12 weeks. Resveratrol (20 mg/kg/day, i.p., during 12 weeks) was given to the Control+Resveratrol and UCMS+Resveratrol groups.Then depressive-like behaviors were evaluated by forced swimming test. After behavioral tests, systolic blood pressure was recorded. Endothelial function of the thoracic aorta was evaluated by isolated organ bath system. Vascular eNOS expression and inflammatory markers such as TNF-α, IL-1β, IL-6, CRP, ICAM1, MCP in serum and vascular tissue were analyzed to explore the mechanisms of resveratrol. UCMS resulted in depressive-like behavior, endothelial dysfunction and increased inflammatory cytokines in both serum and tissue samples. Resveratrol treatment improved depressive-like behavior, ameliorated vascular dysfunction, and reversed stress-induced inflammation. Our findings suggest that resveratrol exerted antidepressant-like effect and prevented vascular endothelial dysfunction by reducing systemic and peripheral inflammation in UCMS-induced depression in rats. Therefore, resveratrol may be a therapeutic option with a vasculoprotective effect in depression.

Examining the Role of Psychosocial Stressors in Hypertension

Despite advances in medicine and preventive strategies, fewer than 1 in 5 people with hypertension have the problem under control. This could partly be due to gaps in fully elucidating the etiology of hypertension. Genetics and conventional lifestyle risk factors, such as the lack of exercise, unhealthy diet, excess salt intake, and alcohol consumption, do not fully explain the pathogenesis of hypertension. Thus, it is necessary to revisit other suggested risk factors that have not been paid due attention. One such factor is psychosocial stress. This paper explores the evidence for the association of psychosocial stressors with hypertension and shows that robust evidence supports the role of a chronic stressful environment at work or in marriage, low socioeconomic status, lack of social support, depression, anxiety, post-traumatic stress, childhood psychological trauma, and racial discrimination in the development or progression of hypertension. Furthermore, the potential pathophysiological mechanisms that link psychosocial stress to hypertension are explained to address the ambiguity in this area and set the stage for further research.

Involvement of the Renin-Angiotensin System in Stress: State of the Art and Research Perspectives

BACKGROUND

Along with other canonical systems, the renin-angiotensin system (RAS) has shown important roles in stress. This system is a complex regulatory proteolytic cascade composed of various enzymes, peptides, and receptors. Besides the classical (ACE/Ang II/AT1 receptor) and the counter-regulatory (ACE2/Ang-(1-7)/Mas receptor) RAS axes, evidence indicates that nonclassical components, including Ang III, Ang IV, AT₂ and AT₄, can also be involved in stress.

OBJECTIVE AND METHODS

This comprehensive review summarizes the current knowledge on the participation of RAS components in different adverse environmental stimuli stressors, including air jet stress, cage switch stress, restraint stress, chronic unpredictable stress, neonatal isolation stress, and post-traumatic stress disorder.

RESULTS AND CONCLUSION

In general, activation of the classical RAS axis potentiates stress-related cardiovascular, endocrine, and behavioral responses, while the stimulation of the counter-regulatory axis attenuates these effects. Pharmacological modulation in both axes is optimistic, offering promising perspectives for stress-related disorders treatment. In this regard, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are potential candidates already available since they block the classical axis, activate the counter-regulatory axis, and are safe and efficient drugs.

Recent Progress of Chronic Stress in the Development of Atherosclerosis

With the development of the times, cardiovascular diseases have become the biggest cause of death in the global aging society, causing a serious social burden. Atherosclerosis is a chronic inflammatory disease, which can occur in large and medium-sized blood vessels in the whole body. It takes atherosclerotic plaque as the typical pathological change and endothelial injury as the core pathophysiological mechanism. It is the pathological basis of coronary heart disease, peripheral artery disease, cerebrovascular disease, and other diseases. Recent studies have shown that chronic stress plays an important role in the occurrence and development of atherosclerosis, endothelial injury, lipid metabolism, and chronic inflammation. This process involves a large number of molecular targets. It is usually the cause of atherosclerotic cardiovascular and cerebrovascular diseases. If chronic stress factors exist for a long time, patients have genetic susceptibility, and the combination of environmental factors triggers the pathogenesis, which may eventually lead to complete blockage of the blood vessels, unstable rupture of plaques, and serious adverse cardiovascular events. This paper reviews the role of chronic stress in the occurrence and development of atherosclerosis, focusing on the pathophysiological mechanism.

Modulatory action of environmental enrichment on hormonal and behavioral responses induced by chronic stress in rats: Hypothalamic renin-angiotensin system components

Environmental enrichment (EE) has been studied as a protocol that can improve brain plasticity and may protect against negative insults such as chronic stress. The aim of this study was to evaluate the effects of EE on the hormonal and behavioral responses induced by chronic mild unpredictable stress (CMS) in rats, considering the involvement of the renin-angiotensin system. Male adult rats were divided into 4 groups: control, CMS, EE, and CMS + EE, and the experimental protocol lasted for 7 weeks. EE was performed during 7 weeks, 5 days per week, 2 h per day. CMS was applied during weeks 3, 4, and 5. After the CMS (week 6), depression-like behavior was evaluated by forced swimming and sucrose consumption tests, anxiety level was evaluated using the elevated plus-maze test, and memory was evaluated using the Y-maze test. On week 7, the animals were euthanized and basal plasma levels of corticosterone and catecholamines were determined. The hypothalamus was isolated and tissue levels of angiotensin peptides were evaluated. CMS increased plasma corticosterone, norepinephrine, and epinephrine basal concentrations, induced depression-like behaviors, impaired memory, and increased hypothalamic angiotensin I, II, and IV concentrations. EE decreased stress hormones secretion, depression-like behaviors, memory impairment, and hypothalamic angiotensin II induced by stress. Reductions of anxiety-like behavior and norepinephrine secretion were observed in both stressed and unstressed groups. The results indicated that EE seemed to protect adult rats against hormonal and behavioral CMS effects, and that the reduction of angiotensin II could contribute to these effects.

Blockade of AT1 type receptors for angiotensin II prevents cardiac microvascular fibrosis induced by chronic stress in Sprague-Dawley rats

To test the effects of chronic-stress on the cardiovascular system, the model of chronic mild unpredictable stress (CMS) has been widely used. The CMS protocol consists of the random, intermittent, and unpredictable exposure of laboratory animals to a variety of stressors, during 3 consecutive weeks. In this study, we tested the hypothesis that exposure to the CMS protocol leads to left ventricle microcirculatory remodeling that can be attenuated by angiotensin II receptor blockade. Male Sprague-Dawley rats were randomly assigned into four groups: Control, Stress, Control + losartan, and Stress + losartan (N = 6, each group, losartan: 20 mg/kg/day). The rats were euthanized 15 days after CMS exposure, and blood samples and left ventricle were collected. Rats submitted to CMS presented increased glycemia, corticosterone, noradrenaline and adrenaline concentration, and losartan reduced the concentration of the circulating amines. Cardiac angiotensin II, measured by high-performance liquid chromatography (HPLC), was significantly increased in the CMS group, and losartan treatment reduced it, while angiotensin 1-7 was significantly higher in the CMS losartan-treated group as compared with CMS. Histological analysis, verified by transmission electron microscopy, showed that rats exposed to CMS presented increased perivascular collagen and losartan effectively prevented the development of this process. Hence, CMS induced a state of microvascular disease, with increased perivascular collagen deposition, that may be the trigger for further development of cardiovascular disease. In this case, CMS fibrosis is associated with increased production of catecholamines and with a disruption of renin-angiotensin system balance, which can be prevented by angiotensin II receptor blockade.

Heart rate variability: the comparison between high tension and normal tension glaucoma

RELEVANCE

Vascular factors may be involved in the development of both high tension glaucoma (HTG) and normal tension (NTG) glaucoma; however, they may be not exactly the same. Autonomic dysfunction characterized by heart rate variability (HRV) is one of the possible reasons of decrease in mean ocular perfusion pressure (MOPP).

PURPOSE

To compare the shift of the HRV parameters in NTG and HTG patients after a cold provocation test (CPT).

METHODS

MOPP, 24-hour blood pressure and HRV were studied in 30 NTG, 30 HTG patients, and 28 healthy subjects. The cardiovascular fitness assessment was made before and after the CPT. The direction and magnitude of the average group shifts of the HRV parameters after CPT were assessed using the method of comparing regression lines in order to reveal the difference between the groups.

RESULTS

MOPP and minimum daily diastolic blood pressure were decreased in HTG and NTG patients compared to healthy subjects. There was no difference in MOPP between HTG and NTG before the CPT. However, all HRV parameters reflected the predominance of sympathetic innervation in glaucoma patients compared to healthy subjects (P < 0.05).Before the CPT, the standard deviation of NN intervals (SDNN) of HRV was lower in HTG compared to NTG, 27.2 ± 4.1 ms and 35.33 ± 2.43 ms (P = 0.02), respectively. After the CPT, SDNN decreased in NTG by 1.7 ms and increased in HTG and healthy subjects by 5.0 ms and 7.09 ms, respectively (P < 0.05). The analysis of relative shift of other HRV parameters after the CPT also revealed a significant difference between NTG and HTG in regard to the predominance of sympathetic innervation in NTG compared to HTG.

CONCLUSION

Patients with NTG have more pronounced disturbance of autonomic nervous system than HTG patients, which is manifested with the activation of sympathetic nervous system in response to CPT. This finding refers to the NTG pathogenesis and suggests the use of HRV assessment in glaucoma diagnosis and monitoring.

Heart rate variability in normal tension glaucoma: A case-control study

Primary vascular dysregulation (PVD) is believed to be a main cause of local vasospasm and impaired autoregulation as a possible contributing factor in the pathogenesis of normal tension glaucoma (NTG). Subjects with PVD respond stronger to psychological stress. Autonomic dysfunction is another reason of instable ocular blood flow and may be studied by means of assessment of heart rate variability (HRV) especially during a hand-cold provocation test (CPT).To compare the shift of HRV parameters in NTG and healthy subjects after a cold provocation test and to assess the relation between structural damage, circulatory parameters and autonomic dysfunction in NTG.HRV was studied using CPT in 78 NTG patients and 60 health control matches. The ocular blood flow was measured using color Doppler imaging (CDI). The 24 hours blood pressure (BP) monitoring was carried out. The cardiovascular fitness assessment was made to all patients before and after CPT. Mean group difference of HRV parameters was compared between NTG and healthy subjects using the Euclidean metric. The mean ocular perfusion pressure (MOPP) was measured. Optic nerve head and retinal nerve fiber layer (RNFL) were evaluated using spectral-domain optic coherence tomography (SD-OCT). The relation between HRV, CDI, and SD-OCT-parameters was assessed.In contrast to healthy subjects, a predominance of the sympathetic activity after the CPT was revealed in the NTG group. The end diastolic velocity (EDV) in central retinal artery (CRA) and short posterior ciliary artery (SPCA) was significantly reduced in NTG compared to healthy eyes. In NTG, the main HRV parameter characterizing the total effect of autonomic blood circulation regulation (SDNN) correlated with MOPP (0.75, P = .035), SPCA EDV (0.93, P < .001), and CRA EDV (0.9, P < .001). The average daily diastolic BP correlated with RNFL (0.67, P = .009).The NTG patients have the disturbance of the autonomic nervous system, which increases in response to stress provocation and is related to ocular blood flow and structural damage.

Relationship among stress, depression, cardiovascular and metabolic changes and physical exercise

Abstract Introduction: Stress is considered one of the most significant health problems in modern society. It can be characterized as any changes in the homeostasis of an individual that require an adaptive response. An imbalance in the secretion of the primary stress mediators may be responsible for the onset and development of several diseases. Thus, chronic stress has been recognized as a risk factor for depression as well as cardiovascular and metabolic diseases. Given the pathophysiological mechanisms associated with chronic stress and related cardiovascular and metabolic changes, it is necessary to implement measures to prevent, control and/or avoid their development. Physical exercise is a non-pharmacological resource that is widely used for this purpose. Its beneficial effects include the improvement of the emotional state as well as lipid and glycemic control. Objective: The aim of this review is to discuss the relationship between stress, depression, cardiovascular and metabolic changes, and highlight the importance of physical exercise in the prevention and treatment of resulting disorders. Materials and Methods: We searched MEDLINE and SCIELO from 2000 through 2012, using the terms chronic stress, mood disorders, depression, cardiovascular and metabolic changes, and exercise. Results: Most of the studies found in our literature search have shown that exercise can attenuate and/or reverse the deleterious effects of chronic stress. Conclusion: Regular physical exercise is useful for maintaining health, especially with respect to improving mood and mental stress.

Role of peripheral vascular resistance for the association between major depression and cardiovascular disease

Major depression and cardiovascular diseases are 2 of the most prevalent health problems in Western society, and an association between them is generally accepted. Although the specific mechanism behind this comorbidity remains to be elucidated, it is clear that it has a complex multifactorial character including a number of neuronal, humoral, immune, and circulatory pathways. Depression-associated cardiovascular abnormalities associate with cardiac dysfunctions and with changes in peripheral resistance. Although cardiac dysfunction in association with depression has been studied in detail, little attention was given to structural and functional changes in resistance arteries responsible for blood pressure control and tissue perfusion. This review discusses recent achievements in studies of depression-associated abnormalities in resistance arteries in humans and animal experimental models. The changes in arterial structure, contractile and relaxing functions associated with depression symptoms are discussed, and the role of these abnormalities for the pathology of major depression and cardiovascular diseases are suggested.

The effects of antidepressants "fluoxetine and imipramine" on vascular abnormalities and Toll like receptor-4 expression in diabetic and non-diabetic rats exposed to chronic stress

Several studies reveal that diabetes doubles the odds of comorbid depression with evidence of a pro-inflammatory state underlying its vascular complications. Indeed, little information is available about vascular effects of antidepressant drugs in diabetes.

METHOD

We investigated the effect of chronic administration of fluoxetine "FLU" and imipramine "IMIP" on behavioral, metabolic and vascular abnormalities in diabetic and non-diabetic rats exposed to chronic restraint stress (CRS).

RESULTS

Both diabetes and CRS induced depressive-like behavior which was more prominent in diabetic/depressed rats; this was reversed by chronic treatment with FLU and IMIP in a comparable manner. Diabetic and non-diabetic rats exposed to CRS exhibited abnormalities in glucose homeostasis, lipid profile and vascular function, manifested by decreased endothelium-dependent relaxation, increased systolic blood pressure and histopathological atherosclerotic changes. Vascular and metabolic dysfunctions were associated with significant increase in aortic expression of TLR-4, and pro-inflammatory cytokines (TNF-α and IL-1ß). FLU ameliorated these metabolic, vascular and inflammatory abnormalities, while IMIP induced either no change or even worsening of some parameters.

CONCLUSION

FLU has favorable effect over IMIP on metabolic, vascular and inflammatory aberrations associated with DM and CRS in Wistar rats, clarifying the preference of FLU over IMIP in management of comorbid depression in diabetic subjects.

Exercise training in hypertension: Role of microRNAs

Hypertension is a complex disease that constitutes an important public health problem and demands many studies in order to understand the molecular mechanisms involving his pathophysiology. Therefore, an increasing number of studies have been conducted and new therapies are continually being discovered. In this context, exercise training has emerged as an important non-pharmacological therapy to treat hypertensive patients, minimizing the side effects of pharmacological therapies and frequently contributing to allow pharmacotherapy to be suspended. Several mechanisms have been associated with the pathogenesis of hypertension, such as hyperactivity of the sympathetic nervous system and renin-angiotensin aldosterone system, impaired endothelial nitric oxide production, increased oxygen-reactive species, vascular thickening and stiffening, cardiac hypertrophy, impaired angiogenesis, and sometimes genetic predisposition. With the advent of microRNAs (miRNAs), new insights have been added to the perspectives for the treatment of this disease, and exercise training has been shown to be able to modulate the miRNAs associated with it. Elucidation of the relationship between exercise training and miRNAs in the pathogenesis of hypertension is fundamental in order to understand how exercise modulates the cardiovascular system at genetic level. This can be promising even for the development of new drugs. This article is a review of how exercise training acts on hypertension by means of specific miRNAs in the heart, vascular system, and skeletal muscle.

Chronic unpredictable mild stress combined with a high-fat diets aggravates atherosclerosis in rats

Background

Depression and high-fat diet are both known as independent risk factors for atherosclerosis and other cardiovascular diseases, suggesting the interaction of psychological and physiological factors in the development of these diseases. The liver is a crucial organ that facilitate lipid metabolism especially in reverse cholesterol transport (RCT), while according to the theory of Traditional Chinese Medicine, depression as a kind of psychological stress has an influence on hepatic function. So there seem to be some links between depression and lipid metabolic disorders.

Methods

To investigate these links, we separately treated rats with chronic unpredictable mild stress (CMS) and/or a high-fat diet (HD) to evaluate the development of atherosclerosis and the expression of hepatic ABCG8, ABCG5, SR-BI, CYP7A1, LXRα, and LCAT which were associated with reverse cholesterol transport.

Results

This study provided evidence that high-fat diet greatly decreased these genes expression related to RCT while chronic stress alone tended to promote RCT. Chronic unpredictable mild stress combined with a high-fat diet attenuated RCT and aggravated atherogenesis.

Conclusions

These observations suggested that chronic psychological stress alone is virtually propitious to lipid metabolism, however when under a condition of high-fat diet, it deteriorated atherosclerotic plague and did harm to RCT.

Association between endothelial dysfunction and depression-like symptoms in chronic mild stress model of depression

OBJECTIVE

Cardiovascular diseases have high comorbidity with major depression. Endothelial dysfunction may explain the adverse cardiovascular outcome in depression; therefore, we analyzed it in vitro. In the chronic mild stress model, some rats develop depression-like symptoms (including "anhedonia"), whereas others are stress resilient.

METHODS

After 8 weeks of chronic mild stress, anhedonic rats reduced their sucrose intake by 55% (7%), whereas resilient rats did not. Acetylcholine-induced endothelium-dependent relaxation of norepinephrine-preconstricted mesenteric arteries was analyzed in nonstressed, anhedonic, and resilient rat groups.

RESULTS

Small resistance arteries from anhedonic rats were less sensitive to acetylcholine than those of the nonstressed and resilient groups (p = .029). Pathways of endothelium-dependent relaxation were altered in arteries from anhedonic rats. Nitric oxide (NO)-dependent relaxation and endothelial NO synthase expression were increased in arteries from anhedonic rats (0.235 [0.039] arbitrary units and 155.7% [8.15%]) compared with the nonstressed (0.135 [0.012] arbitrary units and 100.0% [8.08%]) and resilient (0.152 [0.018] arbitrary units and 108.1% [11.65%]) groups (p < .001 and p = .002, respectively). Inhibition of cyclooxygenase (COX) activity revealed increased COX-2-dependent relaxation in the anhedonic group. In contrast, endothelial NO synthase- and COX-independent relaxation to acetylcholine (endothelium-dependent hyperpolarization-like response) was reduced in anhedonic rats (p < .001). This was associated with decreased transcription of intermediate-conductance Ca-activated K channels.

CONCLUSIONS

Our findings demonstrate that depression-like symptoms are associated with reduced endothelium-dependent relaxation due to suppressed endothelium-dependent hyperpolarization-like relaxation despite up-regulation of the NO and COX-2-dependent pathways in rat mesenteric arteries. These changes could affect peripheral resistance and organ perfusion in major depression.

Insulin resistance is an independent determinate of ED in young adult men

Background

Insulin resistance (IR) triggers endothelial dysfunction, which contributes to erectile dysfunction (ED) and cardiovascular disease.

Aim

To evaluate whether IR was related to ED in young adult patients.

Methods

A total of 283 consecutive men complaining of ED at least six months were enrolled, with a full medical history, physical examination, and laboratory tests collected. Quantitative Insulin Sensitivity Check Index (QUICKI) was used to determine IR. The severity of ED was assessed by IIEF-5 questionnaire. Endothelial function was assessed by ultrasonographic examination of brachial artery flow mediated dilation (FMD).

Results

IR was detected in 52% patients. Subjects with IR had significant higher total cholesterol, triglycerides, low density lipoprotein-cholesterol (LDL-c), glycated haemoglobin (HBA1c), high sensitivity C-reactive protein (hs-CRP) and body mass index (BMI), but showed significant lower IIEF-5 score, FMD%, high density lipoprotein -cholesterol (HDL-c), testosterone, sex hormone binding globulin (SHBG) levels than patients without IR. Multiple regression analysis showed QUICKI and testosterone were independent predictors of IIEF-5 score. Furthermore, the incidence of IR was correlated with the severity of ED.

Conclusions

Compared with other CVFs, IR was found as the most prevalent in our subjects. Besides, IR was independently associated with ED and its severity, suggesting an adverse effect of insulin resistance on erectile function.

The primary vascular dysregulation syndrome: implications for eye diseases

Vascular dysregulation refers to the regulation of blood flow that is not adapted to the needs of the respective tissue. We distinguish primary vascular dysregulation (PVD, formerly called vasospastic syndrome) and secondary vascular dysregulation (SVD). Subjects with PVD tend to have cold extremities, low blood pressure, reduced feeling of thirst, altered drug sensitivity, increased pain sensitivity, prolonged sleep onset time, altered gene expression in the lymphocytes, signs of oxidative stress, slightly increased endothelin-1 plasma level, low body mass index and often diffuse and fluctuating visual field defects. Coldness, emotional or mechanical stress and starving can provoke symptoms. Virtually all organs, particularly the eye, can be involved. In subjects with PVD, retinal vessels are stiffer and more irregular, and both neurovascular coupling and autoregulation capacity are reduced while retinal venous pressure is often increased. Subjects with PVD have increased risk for normal-tension glaucoma, optic nerve compartment syndrome, central serous choroidopathy, Susac syndrome, retinal artery and vein occlusions and anterior ischaemic neuropathy without atherosclerosis. Further characteristics are their weaker blood–brain and blood-retinal barriers and the higher prevalence of optic disc haemorrhages and activated astrocytes. Subjects with PVD tend to suffer more often from tinnitus, muscle cramps, migraine with aura and silent myocardial ischaemic and are at greater risk for altitude sickness. While the main cause of vascular dysregulation is vascular endotheliopathy, dysfunction of the autonomic nervous system is also involved. In contrast, SVD occurs in the context of other diseases such as multiple sclerosis, retrobulbar neuritis, rheumatoid arthritis, fibromyalgia and giant cell arteritis. Taking into consideration the high prevalence of PVD in the population and potentially linked pathologies, in the current article, the authors provide recommendations on how to effectively promote the field in order to create innovative diagnostic tools to predict the pathology and develop more efficient treatment approaches tailored to the person.

Long-term social stress induces nitric oxide-independent endothelial dysfunction in normotensive rats

As chronic stress is a significant risk factor for several cardiovascular disorders, this study investigated the hypothesis that long-term stress produced by crowding may lead to alterations in nitric oxide (NO) production and NO-dependent relaxation in the course of stress, resulting in endothelial dysfunction and hypertension in Wistar-Kyoto (WKY) rats. For this purpose, male WKY rats were divided into control (480 cm2/rat, four rats/cage, n = 8) and crowded (200 cm2/rat, five rats/cage, n = 10) groups for 8 or 12 weeks. Vasorelaxation was evaluated in vitro as a response to acetylcholine (ACh) of femoral arteries pre-contracted by serotonin, before and after NO synthase inhibition (N (G)-nitro-l-arginine methyl ester, 300 μmol/l). Crowding increased plasma corticosterone concentration but failed to affect blood pressure (determined by tail-cuff plethysmography) of rats. NO production was unchanged in the hypothalamus and left ventricle of both stressed groups; however it was significantly elevated in the aorta. Maximal ACh-induced relaxation was elevated significantly after 8-week stress, but reduced after 12 weeks. Stress elevated the NO-dependent component and reduced the NO-independent component of ACh-induced relaxation in both crowded groups. However, a reduction in the NO-independent component was more pronounced after 12-week versus 8-week stress. In conclusion, elevated endothelium-dependent relaxation was observed after 8-week stress, while the extension of stress exposure resulted in a reduction in arterial relaxation associated with a more pronounced decrease of its NO-independent component. Thus, elevation of the NO-dependent component of relaxation can be considered as an adaptation mechanism, and impairment of NO-independent relaxation might be the initial step in chronic stress-induced cardiovascular disorders.

Effects of nandrolone and resistance training on the blood pressure, cardiac electrophysiology, and expression of atrial β-adrenergic receptors

AIMS

This study was performed to assess isolated and combined effects of nandrolone and resistance training on the blood pressure, cardiac electrophysiology, and expression of the β1- and β2-adrenergic receptors in the heart of rats.

MAIN METHODS

Wistar rats were randomly divided into four groups and submitted to a 6-week treatment with nandrolone and/or resistance training. Cardiac hypertrophy was accessed by the ratio of heart weight to the final body weight. Blood pressure was determined by a computerized tail-cuff system. Electrocardiography analyses were performed. Western blotting was used to access the protein levels of the β1- and β2-adrenergic receptors in the right atrium and left ventricle.

KEY FINDINGS

Both resistance training and nandrolone induced cardiac hypertrophy. Nandrolone increased systolic blood pressure depending on the treatment time. Resistance training decreased systolic, diastolic and mean arterial blood pressure, as well as induced resting bradycardia. Nandrolone prolonged the QTc interval for both trained and non-trained groups when they were compared to their respective vehicle-treated one. Nandrolone increased the expression of β1- and β2-adrenergic receptors in the right atrium for both trained and non-trained groups when they were compared to their respective vehicle-treated one.

SIGNIFICANCE

This study indicated that nandrolone, associated or not with resistance training increases blood pressure depending on the treatment time, induces prolongation of the QTc interval, and increases the expression of β1- and β2-adrenergic receptors in the cardiac right atrium, but not in the left ventricle.