Plasma nitrate levels and flow-mediated vasodilation in untreated major depression

Cerebral blood flow in relation to peripheral endothelial function in youth bipolar disorder

INTRODUCTION

Anomalous cerebral blood flow (CBF) is evident in bipolar disorder (BD), however the extent to which CBF reflects peripheral vascular function in BD is unknown. This study investigated endothelial function, an index of early atherosclerosis and cardiovascular disease risk, in relation to CBF among youth with BD.

METHODS

Participants included 113 youth, 13-20 years old (66 BD; 47 healthy controls [HC]). CBF was measured using arterial spin labeling with 3T MRI. Region of interest analyses (ROI; global grey matter, middle frontal gyrus, anterior cingulate cortex, temporal cortex, caudate) were undertaken alongside voxel-wise analyses. Reactive hyperemia index (RHI), a measure of endothelial function, was assessed non-invasively via pulse amplitude tonometry. General linear models were used to examine RHI and RHI-by-diagnosis associations with CBF, controlling for age, sex, and body mass index. Bonferroni correction for multiple comparisons was used for ROI analyses, such that the significance level was divided by the number of ROIs (α = 0.05/5 = 0.01). Cluster-extent thresholding was used to correct for multiple comparisons for voxel-wise analyses.

RESULTS

ROI findings were not significant after correction. Voxel-wise analyses found that higher RHI was associated with lower left thalamus CBF in the whole group (p < 0.001). Additionally, significant RHI-by-diagnosis associations with CBF were found in three clusters: left intracalcarine cortex (p < 0.001), left thalamus (p < 0.001), and right frontal pole (p = 0.006). Post-hoc analyses showed that in each cluster, higher RHI was associated with lower CBF in BD, but higher CBF in HC.

CONCLUSION

We found that RHI was differentially associated with CBF in youth with BD versus HC. The unanticipated association of higher RHI with lower CBF in BD could potentially reflect a compensatory mechanism. Future research, including prospective studies and experimental designs are warranted to build on the current findings.

Oxidative and Nitrosative Stress in Major Depressive Disorder: A Case Control Study

Introduction: The role of increased oxidative stress and alterations to the nitric oxide (NO) pathway have been implicated in major depressive disorder (MDD). The two pathways interact closely with each other but have not been studied simultaneously in MDD. This study aimed to assess and compare the levels of oxidative and nitrosative stress in the neutrophils (PMNs) of drug-naive MDD patients and their first-degree relatives. Methods: 29 drug-naive MDD patients and 27 healthy first-degree relatives and healthy controls aged 18–45 years were included in this study. An assessment of the levels of reactive oxygen species (ROS), nitrites, neuronal NO synthase (nNOS), and myeloperoxidase in PMNs, and cortisol in serum was carried out. Results: Compared to healthy controls, the generation of free radicals, myeloperoxidase activity, and nNOS mRNA expression in PMNs, and cortisol level in serum were significantly higher in drug-naive depression patients. Indeed, increased levels of myeloperoxidase and serum cortisol were also noted in first-degree relatives. The total nitrite content in the PMNs and plasma however was significantly lower in both patients and first-degree relatives. Interestingly, a positive correlation was established in the ROS levels in the PMNs, plasma and neutrophil nitrite, and the serum cortisol level between MDD patients and their first-degree relatives. Conclusion: The results of this study contribute towards a better understanding of the familial association of depressive disorder, and demonstrate for the first time that neutrophil ROS/RNS, plasma nitrite, and serum cortisol levels are positively correlated between MDD patients and their first-degree relatives. However, further studies in larger, more diverse samples are needed to extend these pathways as potential biomarkers to identify persons at high risk for psychopathology at an early stage.

Nitric Oxide Synthase activity in major depressive episodes before and after antidepressant treatment: Results of a large case-control treatment study

BACKGROUND

Nitric oxide synthase (NOS) activity, an enzyme potentially involved in the major depressive episodes (MDE), could be indirectly measured by the L-Citrulline/L-Arginine ratio (L-Cit/L-Arg). The aim of this study was: (1) to compare the NOS activity of patients with a MDE to that of healthy controls (HC); (2) to assess its change after antidepressant treatment.

METHODS

A total of 460 patients with a current MDE in a context of major depressive disorder (MDD) were compared to 895 HC for NOS activity (L-Cit/L-Arg plasma ratio). L-Arg and L-Cit plasma levels were measured using a MS-based liquid chromatography method. Depressed patients were assessed at baseline, and after 3 and 6 months of antidepressant treatment for depression severity and clinical response.

RESULTS

Depressed patients had a lower NOS activity than HC at baseline [0.31 ± 0.09 v. 0.38 ± 0.12; 95% confidence interval (CI) -0.084 to -0.062, p < 0.0001]. Lower NOS activity at baseline predicted a higher response rate [odds ratio (OR) = 29.20; 95% CI 1.58-536.37; p = 0.023]. NOS activity in depressed patients increased significantly up to 0.34 ± 0.08 after antidepressant treatment (Est = 0.0034; 95% CI 0.0002-0.0067; p = 0.03).

CONCLUSIONS

Depressed patients have a decreased NOS activity that improves after antidepressant treatment and predicts drug response. NOS activity may be a promising biomarker for MDE in a context of MDD.

Association between common cardiovascular drugs and depression

Objective:

Cardiovascular diseases are associated with an increased risk of depression, but it remains unclear whether treatment with cardiovascular agents decreases or increases this risk. The effects of drugs on individual usage are also often unknown. This review aimed to examine the correlation between depression and common cardiovascular drugs, develop more potent interventions for depression in cardiovascular patients, and further research on the bio-behavioural mechanisms linking cardiovascular drugs to depression.

Data sources:

The data in this review were obtained from articles included in PubMed, EMBASE, and Web of Science.

Study selection:

Clinical trials, observational studies, review literature, and guidelines about depression and cardiovascular drugs were selected for the article.

Results:

We systematically investigated whether the seven most used cardiovascular drugs were associated with altered risk of incident depression in this literature review. Statins have been proven to have antidepressant effects. Some studies believe angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blocker (ARB) can exert an antidepressant influence by acting on the renin-angiotensin system, but further clinical trials are needed to confirm this. Beta-blockers have previously been associated with depression, but the current study found no significant association between beta blockers and the risk of depression. Aspirin may have antidepressant effects by suppressing the immune response, but its role as an antidepressant remains controversial. calcium channel blockers (CCBs) can regulate nerve signal transduction by adjusting calcium channels, but whether this effect is beneficial or harmful to depression remains unclear. Finally, some cases have reported that nitrates and diuretics are associated with depression, but the current clinical evidence is insufficient.

Conclusions:

Statins have been proven to have antidepressant effect, and the antidepressant effects of ACEIs/ARB and aspirin are still controversial. CCBs are associated with depression, but it is unclear whether it is beneficial or harmful. No association has been found with β-blockers, diuretics, and nitrates.

Endothelial dysfunction in people with depressive disorders: A systematic review and meta-analysis

The study aimed to identify whether people diagnosed with depression have endothelial dysfunction, assessed by the technique of flow-mediated dilation (FMD), when compared to controls without depression. In addition, to verify whether people with depressive symptoms have impaired endothelial function when compared to controls without symptoms. Also to explore the potential moderators of the association between depression and endothelial dysfunction. Systematic review and meta-analysis. We searched PubMed, PsycINFO, Embase and Web of Science, from inception to April 16, 2021, for studies in people with depression and controls evaluating endothelial function through FMD. The primary outcome was the percentage of change in FMD. Comparative random effects meta-analysis, calculating the mean difference (MD) of the FMD between depressed and controls was performed. Potential sources of heterogeneity were explored by meta-regressions and subgroup analyses. The study protocol was registered with PROSPERO (CRD42020192070). Nine studies evaluating 1367 participants (379 depressed and 988 controls) (median age = 39.8 years, 44.9% men) were included. People with depression had lower FMD = -1.48% (95%CI = -2.62 to -0.33). High density lipoprotein (HDL) cholesterol levels moderated the effect (beta = -0.408, 95%CI = -0.776 to -0.040). Differences in FMD were found when assessment was done in the first minute after release of the occlusion, when using occlusion position in distal forearm, and when using occlusion pressure between 250 and 300 mmHg. Those with clinical depression (established by diagnostic instruments) presented the greatest dysfunction. Individuals with depression have a more impaired endothelial dysfunction when compared to controls. HDL cholesterol levels and differences in FMD assessment modalities moderate the difference.

Urine Nitric Oxide Is Lower in Parents of Autistic Children

Parents raising children with autism spectrum disorder (ASD) usually carry on their daily life under tremendous stress, but limited empirical research has been devoted to this population. It is known that parents' health status directly impacts therapeutic outcome of ASD children. As an important regulator in cardiovascular, nervous and immune systems, nitric oxide (NO) levels haven't been reported in parents of ASD children yet. In this study, we measured urine nitrite and nitrate from 43 ASD parents (ASD-P), and 43 healthy adults in the same range of age (Control) who didn't have any ASD descendants. Comparison between the ASD-P and Control groups showed that NO 2 - , NO 3 - , and NO 2 - / NO 3 - were all significantly lower in the ASD-P group. Analysis on the interaction effect of sex and group indicated that urine NO 3 - of mothers in ASD-P was lower than that in females of the Control group, but no significant difference was observed between males in both groups. It is for the first time that urine nitric oxide metabolites (nitrite, nitrate) levels were precisely reported to differentiate parents of autistic children from other adults without ASD descendants. This phenomenon suggests that parents (especially mothers) of autistic children might have experienced more mental and physical stressors, which led to decreased NO levels during metabolism. Further investigations are necessary to uncover the etiology of low urine NO among parents of autistic children.

The Association Between Vascular Inflammation and Depressive Disorder. Causality, Biomarkers and Targeted Treatment

Diabetes, obesity, atherosclerosis, and myocardial infarction are frequently co-morbid with major depressive disorder. In the current review, it is argued that vascular inflammation is a factor that is common to all disorders and that an endothelial dysfunction of the blood-brain barrier could be involved in the induction of depression symptoms. Biomarkers for vascular inflammation include a high plasma level of C-reactive protein, soluble cell-adhesion molecules, von Willebrand factor, aldosterone, and proinflammatory cytokines like interleukin-6 or tumor necrosis factor α. A further possible biomarker is flow-mediated dilation of the brachial artery. Treatment of vascular inflammation is expected to prevent or to reduce symptoms of depression. Several tentative treatments for this form of depression can be envisioned: eicosapentaenoic acid (EPA), valproate, Vagus-nerve stimulation, nicotinic α7 agonists, and agonists of the cannabinoid CB₂-receptor.

Peripheral microvascular serotoninergic signaling is dysregulated in young adults with major depressive disorder

Dysfunction of the brain serotonergic system is implicated in the pathogenesis of major depressive disorder (MDD). Serotonin is also a vasoactive signaling molecule, the effects of which are modulated by both nitric oxide (NO) and the serotonin transporter [the primary target of selective serotonin reuptake inhibitors (SSRIs)]. Despite its role in the neurobiology of depression, serotoninergic signaling mechanisms in the microvasculature of adults with MDD are unknown. We hypothesized that 1) cutaneous microvascular responsiveness to serotonin would be attenuated in MDD and mediated by reductions in both 2) NO-dependent and 3) serotonin reuptake-dependent mechanisms. In 12 adults with MDD (nonmedicated) and 12 nondepressed adults, red cell flux (laser-Doppler flowmetry) was measured during graded intradermal microdialysis perfusion of 1) serotonin (10^-10 to 10^-1 mol/L) alone and in combination with a nonselective NO synthase inhibitor N^G-nitro-l-arginine methyl ester (l-NAME; 15 mmol/L) and the SSRI paroxetine (10 μmol/L); and 2) paroxetine (n = 6; 10^-9 to 10^-2 M) alone and in combination with l-NAME. Serotonin-induced vasodilation was preserved in MDD. The NO-dependent component of serotonin-induced vasodilation was not different between groups. Paroxetine augmented vasodilatory responsiveness to serotonin via NO-dependent mechanisms in both groups; however, the magnitude was blunted in MDD. The NO contribution to direct paroxetine-induced vasodilation was also reduced in adults with MDD. Collectively, these preliminary data suggest that cutaneous microvascular serotoninergic signaling is dysregulated in adults with MDD and mediated by NO-dependent and serotonin reuptake-dependent mechanisms, providing initial mechanistic insight to the purported vasculoprotective effect of chronic SSRI treatment.NEW & NOTEWORTHY Cutaneous microvascular vasodilatory responsiveness to serotonin was preserved in adults with major depressive disorder (MDD). However, the contribution of serotonin reuptake-dependent mechanisms to serotonin-induced dilation was reduced in MDD. Direct perfusion of the selective serotonin reuptake inhibitor (SSRI) paroxetine elicited vasodilation that is partially mediated by nitric oxide (NO)-dependent mechanisms, but these responses were blunted in MDD, reflective of a diminished contribution of NO to the direct effects of a SSRI on the cutaneous microvasculature.

Oxidative Stress Contributes to Microvascular Endothelial Dysfunction in Men and Women With Major Depressive Disorder

RATIONALE

In rodent models of depression, oxidative stress-induced reductions in NO bioavailability contribute to impaired endothelium-dependent dilation. Endothelial dysfunction is evident in major depressive disorder (MDD); however, the molecular mediators remain undefined.

OBJECTIVE

We sought to translate preclinical findings to humans by testing the role of oxidative stress in mediating microvascular endothelial dysfunction, including potential modulatory influences of sex, in MDD.

METHODS AND RESULTS

Twenty-four treatment-naive, otherwise healthy, young adults with MDD (14 women; 18-23 years) and 20 healthy adults (10 women; 19-30 years) participated. Red blood cell flux (laser Doppler flowmetry) was measured during graded intradermal microdialysis perfusion of the endothelium-dependent agonist acetylcholine, alone and in combination with an NO synthase inhibitor (L-NAME), a superoxide scavenger (Tempol), and an NADPH oxidase inhibitor (apocynin), as well as during perfusion of the endothelium-independent agonist sodium nitroprusside. Tissue oxidative stress markers (eg, nitrotyrosine abundance, superoxide production) were also quantified. Endothelium-dependent dilation was blunted in MDD and mediated by reductions in NO-dependent dilation. Endothelium-independent dilation was likewise attenuated in MDD. In MDD, there were no sex differences in either NO-mediated endothelium-dependent dilation or endothelium-independent dilation. Acute scavenging of superoxide or inhibition of NADPH oxidase improved NO-dependent dilation in MDD. Expression and activity of oxidative stress markers were increased in MDD. In a subset of adults with MDD treated with a selective serotonin reuptake inhibitor for their depressive symptoms and in remission (n=8; 7 women; 19-37 years), NO-mediated endothelium-dependent dilation was preserved, but endothelium-independent dilation was impaired, compared with healthy adults.

CONCLUSIONS

Oxidative stress-induced reductions in NO-dependent dilation, as well as alterations in vascular smooth muscle function, directly contribute to microvascular dysfunction in MDD. Strategies targeting vascular oxidative stress may be viable therapeutic options for improving NO-mediated endothelial function and reducing cardiovascular risk in MDD.

Water contaminant levels interact with parenting environment to predict development of depressive symptoms in adolescents

Contaminants in drinking water, such as lead, nitrate, and arsenic, have been linked to negative physical health outcomes. We know less, however, about whether such pollutants also predict mental health problems and, if so, the conditions under which such effects are strongest. In this longitudinal study, we examined whether drinking water contaminants interact with negative family environments (parental psychological control) to predict changes in depressive symptoms in 110 adolescents-a developmental period when symptoms often first emerge. We found that for adolescents in psychologically controlling families, levels of drinking water contaminants prospectively predicted depressive symptoms 2 years later; this effect was not present in adolescents in non-controlling families. Importantly, these associations were not accounted for by family- or community-level socioeconomic resources, demographic features, or by the adolescents' stress exposure. These findings highlight the interplay of physical and psychological environments in influencing depressive symptoms in adolescents. A video abstract of this article can be viewed at https://youtu.be/thBV-DwnGcY.

Depressive Symptoms During Childhood and Cardiovascular Risk Factors in Black and White Men

OBJECTIVE

Depressive symptoms and major depression predict cardiovascular disease (CVD) and CVD risk factors in adulthood. Evidence regarding the role of depression in the development of CVD risk in youth is minimal. The study evaluated the prospective relationship of depressive symptoms in childhood and adolescence with adult CVD risk factors in black and white men.

METHODS

Health behaviors and medical history were measured in 165 black and 146 white men (mean age = 32); a subset in the Pittsburgh area had a fasting blood draw to measure metabolic syndrome and inflammation. Adult CVD risk factors were related to depressive symptoms and childhood socioeconomic status (SES) prospectively measured annually from ages 7 to 16 years, followed by adjustments for adult SES and depressive symptoms.

RESULTS

Men with higher depressive symptoms ages 7 to 16 smoked more cigarettes, B = 0.28 (standard error = 0.12), p = .015, and ate fewer servings of fruits and vegetables, B = -0.08 (0.04), p = .040, as adults. The association for smoking was independent of adult depressive symptoms (concurrent) and childhood and adult SES as well as race. Depressive symptoms during childhood were unrelated to the metabolic syndrome or biomarkers of inflammation in adulthood.

CONCLUSIONS

Depressive symptoms in childhood may predict later adverse health behaviors in black and white men. No evidence was found for an association between childhood depressive symptoms with metabolic syndrome or inflammation markers at ages approximately 32 years. The nature of the sample and lack of measurement of depressive disorder diagnosis tempers the conclusions, and future research is needed to determine associations with biological measures at later life span phases.

Roles of Gasotransmitters in Synaptic Plasticity and Neuropsychiatric Conditions

Synaptic plasticity is important for maintaining normal neuronal activity and proper neuronal functioning in the nervous system. It is crucial for regulating synaptic transmission or electrical signal transduction to neuronal networks, for sharing essential information among neurons, and for maintaining homeostasis in the body. Moreover, changes in synaptic or neural plasticity are associated with many neuropsychiatric conditions, such as schizophrenia (SCZ), bipolar disorder (BP), major depressive disorder (MDD), and Alzheimer's disease (AD). The improper maintenance of neural plasticity causes incorrect neurotransmitter transmission, which can also cause neuropsychiatric conditions. Gas neurotransmitters (gasotransmitters), such as hydrogen sulfide (H2S), nitric oxide (NO), and carbon monoxide (CO), play roles in maintaining synaptic plasticity and in helping to restore such plasticity in the neuronal architecture in the central nervous system (CNS). Indeed, the upregulation or downregulation of these gasotransmitters may cause neuropsychiatric conditions, and their amelioration may restore synaptic plasticity and proper neuronal functioning and thereby improve such conditions. Understanding the specific molecular mechanisms underpinning these effects can help identify ways to treat these neuropsychiatric conditions.

The relationship of depressive symptoms and functional and structural markers of subclinical atherosclerosis: A systematic review and meta-analysis

Objectives

The relationship of depressive symptoms and subclinical atherosclerosis remains controversial. We performed a systematic review and meta-analysis to evaluate the effect of depressive symptoms on the functional and structural markers of subclinical atherosclerosis as measured by carotid intima-media thickness (IMT), pulse wave velocity (PWV) and flow-mediated vasodilation (FMD).

Methods

A systematic literature search was performed electronically. Studies relating IMT, PWV or FMD to depressive symptoms were included. Standard/weighted mean differences (SMD/WMD) and corresponding 95% confidence intervals (95% CIs) were pooled in overall and subgroup analyses (age, sex, depression diagnosis, region, study design, site measured and sample size). Sensitivity analysis and publication bias were also conducted.

Results

Thirty-eight articles involving 5947 patients with depressive symptoms and 34,423 controls without depressive symptoms were included. Compared with controls without depressive symptoms, patients with depressive symptoms showed a significantly thicker IMT (SMD (95% CI) = 0.137 (0.047–0.227), p = 0.003), a higher PWV (SMD (95% CI) = 0.216 (0.139–0.293), p < 0.001) and a lower FMD (WMD (95% CI) = –2.554 (–3.709 to –1.399), p < 0.001). When analyzing subgroups with age and female ratio, all results were still significant ( p < 0.05) except IMT and FMD in age < 50 years subgroups ( p > 0.05). There was no statistical significance in sensitivity analysis and publication bias ( p > 0.05).

Conclusions

Depressive symptoms contributed toward subclinical atherosclerosis, and resulted in impaired functional and structural markers of subclinical atherosclerosis, which holds great promise in early prevention of cardiovascular disease.

The changes in, and relationship between, plasma nitric oxide and corticotropin-releasing hormone in patients with major depressive disorder

There is strong evidence of roles of the hypothalamus-pituitary-adrenal axis and nitric oxide (NO) synthase-NO system in depression, but the relationship between them is unknown. The aim of this study, therefore, was to elucidate whether there is any correlation between NO and corticotropin-releasing hormone (CRH) in major depressive disorder (MDD) patients. In 16 outpatients with MDD and 18 healthy controls, the plasma amino acids citrulline (Cit) and arginine (Arg) were determined by high-performance liquid chromatography, and CRH levels was measured by radioimmunoassay. The Cit/Arg ratio was calculated as an index of NO synthesis. Correlations between NO and CRH were examined with the Spearman test. Before treatment, no significant correlation was observed between the plasma NO level and CRH levels in MDD patients. The plasma NO levels were significantly higher in MDD patients. A significant correlation was found between NO levels and Hamilton Depression Rating Scale (HAMD) scores in MDD patients. The plasma CRH levels were significantly higher in MDD patients than in controls. After monotherapy for 2 months, the NO levels had dramatically declined but were also higher than those in the controls. This study is the first report of the absence of a significant correlation between plasma NO and CRH levels, although both levels are elevated in MDD patients. Furthermore, the strong links between the plasma NO levels and the HAMD scores, as well as the increased NO reduction after remission, suggest that NO plays a key role in depression and may be an indicator of therapeutic success.

Ketamine upregulates eNOS expression in human astroglial A172 cells: Possible role in its antidepressive properties

Ketamine is a potent anti-depressive agent. Nitric oxide plays an essential role in neuronal transmission and cerebral blood flow and has been implicated in the pathophysiology of major depressive disorder as well as cardiovascular functioning. We investigated the effect of ketamine on eNOS expression in human A172 astroglial cells. Ketamine (50-500μM) increased eNOS expression at 4-24h in a concentration-dependent manner. This effect was mediated by NMDA receptor, Akt inhibition and ERK1/2 activation and was synergistically augmented by rapamycin. The combined effect on the vascular, immune and neuronal systems may be relevant to the rapid antidepressive effect of ketamine.

The impact of major depression on heart rate variability and endothelial dysfunction in patients with stable coronary artery disease

BACKGROUND

Depression is an independent risk factor in cardiovascular diseases. Changes in the cardiac autonomic functions and pro-inflammatory processes are potential biological factors. Endothelial dysfunction plays an important role in the etiopathogenesis of atherosclerosis. Our objective was to evaluate the impact of major depression on heart rate variability and endothelial dysfunction in patients with stable CAD.

METHODS

The study group included 65 CAD patients with a diagnosis of major depression and 54 CAD patients without major depression. All study population underwent transthoracic echocardiography, measurement of flow mediated dilatation (FMD) and 24-h holter recording for heart rate variability (HRV). Blood samples were drawn to determine the inflammatory parameters. Severity of depressive episode was assessed by Montgomery-Asberg Depression Scale (MADRS).

RESULTS

The distribution of age and sex was similar in the patient and control groups (P=0.715, 0.354, respectively). There was no significant difference in medications used between the groups. Echocardiographic parameters were similar between the groups. Inflammatory parameters were also similar between the groups. HRV parameters were significantly lower in the patient group than controls. The absolute FMD value and percentage FMD were significantly lower in the patient group than controls (P<0.001). The MADRS score correlated with pNN50 in both groups (P<0.05), and with FMD in the control group (P<0.001), even after adjusting for age and gender (P<0.001).

CONCLUSIONS

MADRS score was an independent predictor of pNN50 level, percentage and absolute FMD values regardless of age and gender. Clinician should pay more attention for evaluation of depressive patients with CAD.

Intracoronary Des-Acyl Ghrelin Acutely Increases Cardiac Perfusion Through a Nitric Oxide-Related Mechanism in Female Anesthetized Pigs

Des-acyl ghrelin (DAG), the most abundant form of ghrelin in humans, has been found to reduce arterial blood pressure and prevent cardiac and endothelial cell apoptosis. Despite this, data regarding its direct effect on cardiac function and coronary blood flow, as well as the related involvement of autonomic nervous system and nitric oxide (NO), are scarce. We therefore examined these issues using both in vivo and in vitro studies. In 20 anesthetized pigs, intracoronary 100 pmol/mL DAG infusion with a constant heart rate and aortic blood pressure, increased coronary blood flow and NO release, whereas reducing coronary vascular resistances (P < .05). Dose responses to DAG were evaluated in five pigs. No effects on cardiac contractility/relaxation or myocardial oxygen consumption were observed. Moreover, whereas the blockade of muscarinic cholinoceptors (n = 5) or α- and β-adrenoceptors (n = 5 each) did not abolish the observed responses, NO synthase inhibition (n = 5) prevented the effects of DAG on coronary blood flow and NO release. In coronary artery endothelial cells, DAG dose dependently increased NO release through cAMP signaling and ERK1/2, Akt, and p38 MAPK involvement as well as the phosphorylation of endothelial NO synthase. In conclusion, in anesthetized pigs, DAG primarily increased cardiac perfusion through the involvement of NO release. Moreover, the phosphorylation of ERK1/2 and Akt appears to play roles in eliciting the observed NO production in coronary artery endothelial cells.

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.

Examining Endothelial Function and Platelet Reactivity in Patients with Depression before and after SSRI Therapy

Although it is recognized that patients with major depressive disorder (MDD) are at increased risk of developing cardiovascular disease (CVD) the mechanisms responsible remain unknown. Endothelial dysfunction is one of the first signs of CVD. Using two techniques, flow-mediated dilatation in response to reactive hyperemia and laser Doppler velocimetry with iontophoresis, we examined endothelial function in the forearm before and after serotonin-specific reuptake inhibitor (SSRI) treatment in 31 patients with MDD. Measurement of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, soluble P-selectin, and noradrenaline in plasma was also performed. Prior to treatment, markers of endothelial and vascular function and platelet reactivity were within the normal range. Following SSRI therapy (95 ± 5 days) symptoms of depression were reduced (paired difference between pre- and post-treatment Hamilton rating -18 ± 1, P < 0.001) with 19 patients recovered and 4 remitted. There occurred no significant change in markers of endothelial or vascular function following SSRI therapy. The improvement in Hamilton depression rating in response to therapy could be independently predicted by the baseline arterial plasma noradrenaline concentration (r (2) = 0.36, P = 0.003). In this cohort of patients with MDD, SSRI therapy did not influence endothelial function or markers of vascular or platelet reactivity. Patient response to SSRI therapy could be predicted by the initial circulating level of noradrenaline, with noradrenaline levels being lower in responders.

Major Depressive Disorder and Bipolar Disorder Predispose Youth to Accelerated Atherosclerosis and Early Cardiovascular Disease: A Scientific Statement From the American Heart Association

In the 2011 "Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents," several medical conditions among youth were identified that predispose to accelerated atherosclerosis and early cardiovascular disease (CVD), and risk stratification and management strategies for youth with these conditions were elaborated. Major depressive disorder (MDD) and bipolar disorder (BD) among youth satisfy the criteria set for, and therefore merit inclusion among, Expert Panel tier II moderate-risk conditions. The combined prevalence of MDD and BD among adolescents in the United States is ≈10%, at least 10 times greater than the prevalence of the existing moderate-risk conditions combined. The high prevalence of MDD and BD underscores the importance of positioning these diseases alongside other pediatric diseases previously identified as moderate risk for CVD. The overall objective of this statement is to increase awareness and recognition of MDD and BD among youth as moderate-risk conditions for early CVD. To achieve this objective, the primary specific aims of this statement are to (1) summarize evidence that MDD and BD are tier II moderate-risk conditions associated with accelerated atherosclerosis and early CVD and (2) position MDD and BD as tier II moderate-risk conditions that require the application of risk stratification and management strategies in accordance with Expert Panel recommendations. In this scientific statement, there is an integration of the various factors that putatively underlie the association of MDD and BD with CVD, including pathophysiological mechanisms, traditional CVD risk factors, behavioral and environmental factors, and psychiatric medications.

Nonlinear digital signal processing in mental health: characterization of major depression using instantaneous entropy measures of heartbeat dynamics

Nonlinear digital signal processing methods that address system complexity have provided useful computational tools for helping in the diagnosis and treatment of a wide range of pathologies. More specifically, nonlinear measures have been successful in characterizing patients with mental disorders such as Major Depression (MD). In this study, we propose the use of instantaneous measures of entropy, namely the inhomogeneous point-process approximate entropy (ipApEn) and the inhomogeneous point-process sample entropy (ipSampEn), to describe a novel characterization of MD patients undergoing affective elicitation. Because these measures are built within a nonlinear point-process model, they allow for the assessment of complexity in cardiovascular dynamics at each moment in time. Heartbeat dynamics were characterized from 48 healthy controls and 48 patients with MD while emotionally elicited through either neutral or arousing audiovisual stimuli. Experimental results coming from the arousing tasks show that ipApEn measures are able to instantaneously track heartbeat complexity as well as discern between healthy subjects and MD patients. Conversely, standard heart rate variability (HRV) analysis performed in both time and frequency domains did not show any statistical significance. We conclude that measures of entropy based on nonlinear point-process models might contribute to devising useful computational tools for care in mental health.

Oxidative stress and major depression

BACKGROUND

Major causative factor for major depression is inflammation, autoimmune tissue damage and prolonged psychological stress, which leads to oxidative stress. The aim of this study was to know the association of free radicals and antioxidant status in subjects suffering from major depression.

MATERIALS AND METHODS

Sixty patients diagnosed as a case of unipolar depression as per DSM IV, fulfilling the inclusion and exclusion criteria were compared with 40 healthy age and sex matched controls. The sera of both the groups were collected taking aseptic precautions and were evaluated for the markers of oxidative stress and for the antioxidants. The age group of the sample and the controls was between 18-60 y, both males and females were equally represented in the groups.

RESULTS

A significantly high level of malondialdehyde (MDA) was found in the patients with major depression (1.95 ± 1.04 mmol/L) as compared to healthy controls (0.366 ± 0.175 mmol/L) (p < 0.0001). The serum level of nitrite was found to be lower in cases (23.18 ± 12.08 μmol/L) in comparison to controls (26.18 ± 8.68 μmol/L) (p = 0.1789). Similarly the serum level of ascorbic acid and superoxide dismutase (SOD) were significantly below as compared to healthy controls (all p < 0.0001). Ceruloplasmin levels were also depressed in cases (p = 0.3943).

CONCLUSION

The study concluded that in the absence of known oxidative injury causative agents, the lowered levels of antioxidants and higher levels of MDA implicate the high degree of oxidative stress in unipolar depression.

Increases in exhaled nitric oxide after acute stress: association with measures of negative affect and depressive mood

BACKGROUND

Increases in fractional exhaled nitric oxide (FeNO) have been observed after acute laboratory stress, which could indicate a strengthening of immune defenses in acute stress because of the quick onset of the response and the role of nitric oxide in airway-protective functions. In addition, because sustained psychological distress and depression are known to deteriorate immune defenses systems, they may dampen the FeNO response to acute stress.

METHODS

FeNO and negative affect were measured before and after a speech and mental arithmetic stressor. We examined the association of stress-induced FeNO changes with momentary negative affect and questionnaires of perceived stress, anxious mood, and depressive mood in 39 asthma patients and 41 healthy controls.

RESULTS

FeNO increased from baseline to stress in participants with asthma (from 3.38 [0.102] to 3.46 [0.103] ln(ppb)) and controls (2.86 [0.098] to 2.92 [0.099]; F(4,141) = 3.26, p = .014), but the magnitude of the FeNO response did not differ between groups (F < 1). Only low levels of depressive mood were associated with FeNO increases after stress (most pronounced at 0 minute poststress; t(76) = 3.87, p < .001). In contrast, only higher perceived stress was associated with FeNO increases (most pronounced at 0 minute poststress; t(75) = 4.09, p < .001), and momentary negative affect was associated with higher FeNO throughout assessments (β = 0.08, t(114) = 8.27, p = .005). Associations of FeNO with psychological variables were largely unrelated to asthma status and inhaled corticosteroid use.

CONCLUSIONS

Depressive mood is associated with a reduced mobilization of airway nitric oxide in acute stress, whereas other indicators of negative affect are positively associated with overall FeNO levels and reactivity.

Depression and cardiovascular disease: an update on how course of illness may influence risk

Depression constitutes a novel and independent risk factor for cardiovascular disease, which despite extensive support in the literature has been underappreciated. While much of the evidence for depression as a risk factor for cardiovascular disease is based on studies following myocardial infarction, the elevated vascular risk conveyed by depression is not confined to periods following acute coronary syndromes. For that matter, the risk appears across mood disorders with evidence for even greater risk in bipolar disorder. This review summarizes the literature linking depressive disorders to cardiovascular mortality with a focus on how the course of illness of mood disorders may influence this risk. Mood disorders may influence risk over decades of illness in a dose-response to symptom burden, or the persistence of affective symptomatology. This may be mediated through changes in the activity of the autonomic nervous system, the hypothalamic-pituitary-adrenal axis, and inflammatory cytokines. Whether treatment of depression can mitigate this risk is not established although there are suggestions to support this contention, which could be better studied with more effective treatments of depression and larger standardized samples. Directions for future study of mechanisms and treatment are discussed. Regardless of causal mechanisms, persons with depressive disorders and other risk factors for vascular disease represent a neglected, high-risk group for cardiovascular events. In addition to the appropriate treatment for depression, screening and optimized management of traditional risk factors for cardiovascular diseases is necessary.

Lithium increases nitric oxide levels in subjects with bipolar disorder during depressive episodes

BACKGROUND

Altered nitric oxide (NO) signaling has been associated with the pathophysiology of Bipolar Disorder (BD), directly affecting neurotransmitter release and synaptic plasticity cascades. Lithium has shown to regulate NO levels in preclinical models. However, no study has addressed peripheral NO levels in unmedicated BD. Also, lithium's effects on NO levels have not been studied in humans.

METHODS

Plasma NO was evaluated in subjects with BD I and II during a depressive episode (n = 26). Subjects had a score of ≥18 in the 21-item Hamilton Depression Rating Scale and were followed-up during a 6-week trial with lithium. Plasma NO levels were also compared to matched healthy controls (n = 28). NO was determined by chemiluminescence method.

RESULTS

Lithium treatment significantly increased plasma NO levels after 6 weeks of treatment in comparison to baseline levels in bipolar depression (p = 0.016). Baseline NO levels during depressive episodes showed no difference when matching up to healthy controls (p = 0.66).

CONCLUSION

The present findings suggest that lithium upregulates NO signaling in unmedicated BD with short illness duration. Further studies with larger samples are needed to confirm the effects of lithium on NO pathway and its association with synaptic plasticity and therapeutics of BD.

Possible role of adrenomedullin and nitric oxide in major depression

Adrenomedullin (ADM) and nitric oxide (NO) have been implicated in the pathogenesis of certain psychiatric disorders such as schizophrenia and bipolar disorder. ADM induces vasorelaxation by activating adenylate cyclase and stimulating the release of NO. These two molecules are known to influence cerebral activity. In this study, we aimed to examine the serum levels of ADM and NO in patients with major depression (MD). We enrolled 50 patients with MD and 50 healthy control subjects. The diagnosis of MD was established on the basis of a structured clinical interview using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). The severity of depressive symptoms was evaluated using Hamilton's 17-item Depression Rating Scale. The mean serum levels of ADM and NO in patients with MD were significantly higher than those in healthy subjects (p=0.001, for both). The severity of psychomotor retardation in patients with MD was significantly correlated with the ADM (r=0.37, p=0.007) and NO levels (r=0.29, p=0.038). The patients with obvious psychomotor retardation had significantly higher levels of ADM and NO than did the patients with no psychomotor retardation (p=0.025, p=0.030). A significantly positive correlation was found between ADM and NO levels in patients with MD (r=0.79, p=0.001). Serum levels of ADM and NO levels were not correlated with the severity or duration of depression or depressive symptoms (except psychomotor retardation). In conclusion, our study indicates that serum levels of ADM and NO are elevated in patients with MD and that increased serum levels of ADM and NO may be associated with psychomotor retardation. The ADM-NO system may serve as a new target in the treatment of patients with MD and psychomotor retardation.

Defective nitric oxide-cyclic guanosine monophosphate signaling in patients with bipolar disorder: a potential role for platelet dysfunction

OBJECTIVE

Bipolar disorder (BD) is associated with elevated cardiovascular mortality rates. We investigated the modulation of l-arginine-nitric oxide (NO) signaling in platelets from patients with BD at different phases.

METHODS

Platelets obtained from 28 patients with BD and 10 healthy volunteers were analyzed for l-arginine transport, NO synthase (NOS) activity, cyclic guanosine monophosphate content, and biomarkers of oxidative stress. Expressions of NOS isoforms, soluble guanylyl cyclase, and arginase were also measured in platelets. Amino acid and C-reactive protein levels in plasma were assessed.

RESULTS

Plasma concentrations of l-arginine (mean [M] ± standard error of the mean [SEM] = 97 ± 10 versus 121 ± 10 µM) and its transport into platelets (median [interquartile range] = 26.0 [28.6] versus 26.5 [43.9] pmol/10(9) cells per minute) did not differ between patients with BD and controls (p > .05). Patients with BD showed reduced NOS activity (M ± SEM = 0.037 ± 0.003 versus 0.135 ± 0.022 pmol/10(8) cells, p < .001), but not endothelial NOS, inducible NOS, and arginase expression, compared with controls (p > .05). Cyclic guanosine monophosphate content was reduced (M ± SEM = 0.022 ± 0.003 versus 0.086 ± 0.020 pmol/10(8) cells, p < .05) despite the absence of changes in soluble guanylyl cyclase expression (median [interquartile range] = 21.6 [15.5] versus 9.5 [9.4] arbitrary units, p > .05) in patients with BD. Superoxide dismutase activity, but not catalase activity, was increased in patients with BD in the manic phase (M ± SEM = 2094 ± 335 versus 172 ± 17 U/mg protein, p < .001). C-reactive protein was elevated only in manic episodes (M ± SEM = 0.8 ± 0.2 versus 0.1 ± 0.02 mg/L, p < .001).

CONCLUSIONS

Impaired NO generation from platelets, inflammation, and oxidative stress may play pivotal roles in the multifaceted process of cardiovascular events in BD.

Impairment of endothelial protection by ischemic postconditioning in patients with major depressive disorder

This study used a model of ischemia–reperfusion injury to the brachial artery endothelium to investigate whether the protective role of ischemic postconditioning (IPostC) is impaired in patients with major depressive episode. Flow-mediated dilation (FMD) was measured before and after ischemia–reperfusion in the absence or presence of IPostC in 24 patients with major depressive disorder and 20 healthy controls. In addition, the severity of the depression, as assessed by the Hamilton Depression Rating Scale (HDRS) and Beck Depression Inventory (BDI) scores, and plasma nitrogen dioxide (NOx) levels were also determined. Ischemia–reperfusion resulted in a significant decrease in FMD in both patients with a major depressive episode and healthy controls. IPostC effectively prevented this decrease in FMD in healthy controls, but not in patients with a major depressive episode. HDRS and BDI scores were markedly increased, but plasma NOx levels decreased, in patients with a major depressive episode compared with those in healthy controls. Correlation analysis showed that HDRS and BDI scores and plasma NOx levels were significantly associated with post-ischemia–reperfusion FMD. These results suggest that endothelial protection by IPostC is impaired in patients with major depressive disorder, which may be related to the decrease in endothelial nitric oxide production and the severity of the depression.