Dynamic proteomic analysis of protein expression profiles in whole brain of Balb/C mice subjected to unpredictable chronic mild stress: implications for depressive disorders and future therapies

Serotonergic-dependent effects of exercise and elevated stress hormone on small non-coding RNA transcriptomics and proteomics in a mouse model of affective disorders

Environmental changes may alter gene expression in depression and anxiety disorders through epigenetic regulation, including via small non-coding RNAs (sncRNAs) and their major subclass, microRNAs (miRNAs). However, underlying mechanisms mediating miRNA regulation in response to changing environmental stimuli are unclear. Using the serotonin transporter (5-HTT) knockout (KO) mouse model of depression/anxiety, this study aimed to compare the effects of voluntary exercise (EX) versus chronic treatment with the stress hormone corticosterone (CT), on hippocampal miRNA transcriptome and proteome in five comparison groups: WT-SH vs. KO-SH; WT-SH vs. WT-EX; KO-SH vs. KO-EX; WT-SH vs. WT-CT; KO-SH vs. KO-CT. We hypothesized that treatment with stress hormone will result in miRNA and proteomics changes observed in genetic model of depression, while exercise will have beneficial effects similar to antidepressant treatment. Using high-throughput sequencing of miRNAs and mass spectrometry (MS)-based approaches for protein expression, we revealed 337 differentially expressed (DE) miRNAs and 67 proteins in 5-HTT KO mice compared to wild-type (WT) control mice in standard-housing conditions. After exercise, there were 200 DE miRNAs and 3 DE proteins in WT mice, and 20 DE miRNAs and 95 DE proteins in 5-HTT KO mice, while corticosterone treatment led to 168 DE miRNAs and 1 DE protein in WT, and 21 DE miRNAs and 21 DE proteins in 5-HTT KO mice. Serotonergic dysfunction (due to the 5-HTT KO gene mutation) induced altered expression of miRNAs and proteins involved in regulation of neurodevelopment, neurogenesis and neuroinflammatory responses. Treatment with the stress hormone corticosterone in WT mice activated pathways which were also found altered in 5-HTT KO mice, while exercise caused antidepressant-like effects. These findings suggest that functional 5-HTT might be required for the beneficial effects of exercise on miRNA expression. Our study is the first to explore how gene-environment interactions affect miRNA/proteomic composition in a mouse model of depression/anxiety, and extends our understanding of gene-environmental interactions underlying these affective disorders.

CUMS induces depressive-like behaviors and cognition impairment by activating the ERS-NLRP3 signaling pathway in mice

BACKGROUND AND OBJECTIVE

Endoplasmic reticulum stress (ERS), as a primary defense mechanism against stress, is closely related to mental disorders, but its pathogenesis is still unclear. This research seeks to explore the influence of ERS-nucleotide-bound oligomerized domain-like receptor protein 3 (NLRP3) signaling on mice's depressive-like behaviors and cognitive impairment.

DESIGN AND METHOD

We carried out a study on 32 male C57BL/6J mice to investigate how chronic unpredictable mild stress (CUMS) can give rise to depressive-like behaviors and cognitive dysfunction, randomly dividing them into control, model, inhibitor, and agonist groups. We utilized ELISA to quantify dopamine (DA) and 5-hydroxytryptamine (5-HT) levels. Using Nissl and hematoxylin and eosin (H&E) staining, we assessed the number and morphology of hippocampal neurons and cells. Western blot and immunofluorescence staining detected the changes in ERS and inflammation-related pathways in the hippocampus.

RESULTS

CUMS could induce ERS and activate NLRP3 inflammasome, causing neuronal damage and histopathological changes, eventually leading to depressive-like behaviors and cognitive impairment in mice. The abnormal activation of NLRP3 inflammasome could be restored by ERS blocker 4-phenyl butyric acid (PBA), thus reducing neuronal damage, and ameliorating depressive-like behaviors and cognitive disorder in mice.

CONCLUSION

Our study demonstrates a previously unknown link between ERS and NLRP3 inflammasome in CUMS mice. The ERS-NLRP3 signaling pathway may be activated by CUMS, potentially resulting in mice exhibiting depressive-like behaviors and cognitive dysfunction. Theoretical foundations for elucidating the pathogenesis of depression, as well as its prevention and treatment, will be established through the results.

Prolonged stress-induced depression-like behaviors in aged rats are mediated by endoplasmic reticulum stress and apoptosis in the hippocampus

Structural and functional recovery from stress-induced depression is impaired in the context of aging brain. Since investigating the molecular substrates that facilitate behavioral recovery may have important implications for understanding brain plasticity and resilience of individuals, we studied depressive-like behaviors in young and aged rats 6 weeks after chronic stress exposure as a recovery period and examined the levels of TNF-α and IL-6 inflammatory cytokines, NADH oxidase activity, NADPH oxidase, endoplasmic reticulum (ER) stress markers, and apoptosis in the hippocampus. Young (3 months old) and aged (22 months old) male Wistar rats were divided into four groups; young control (Young), depression model of young rats that received chronic stress procedure followed by a 6-week recovery period (Young+S), aged control (Aged), and depression model of aged rats that received chronic stress procedure followed by a 6-week recovery period (Aged+S). After the recovery period, aged but not young rats showed depression-like behaviors, evaluated by the sucrose preference test (SPT) and forced swimming test (FST), coincided with the altered levels of TNF-α, IL-6, NADH oxidase activity, NADPH oxidase, GRP78, CHOP, and cleaved caspase-12 in the hippocampus of these animals. These data suggested that oxidative and ER stress-induced apoptosis in the aging hippocampus may affect the recovery-related outcomes after the stress paradigm.

Connecting Dots between Mitochondrial Dysfunction and Depression

Mitochondria are the prime source of cellular energy, and are also responsible for important processes such as oxidative stress, apoptosis and Ca2+ homeostasis. Depression is a psychiatric disease characterized by alteration in the metabolism, neurotransmission and neuroplasticity. In this manuscript, we summarize the recent evidence linking mitochondrial dysfunction to the pathophysiology of depression. Impaired expression of mitochondria-related genes, damage to mitochondrial membrane proteins and lipids, disruption of the electron transport chain, higher oxidative stress, neuroinflammation and apoptosis are all observed in preclinical models of depression and most of these parameters can be altered in the brain of patients with depression. A deeper knowledge of the depression pathophysiology and the identification of phenotypes and biomarkers with respect to mitochondrial dysfunction are needed to help early diagnosis and the development of new treatment strategies for this devastating disorder.

Dietary Strategies for Relieving Stress in Pet Dogs and Cats

A variety of physical, emotional, and mental factors can induce a stress response in pet dogs and cats. During this process, hypothalamus-pituitary-adrenal (HPA) and sympathetic-adrenal medulla (SAM) axes are activated to produce a series of adaptive short-term reactions to the aversive situations. Meanwhile, oxidative stress is induced where there is an imbalance between the production and scavenging of reactive oxygen species (ROS). Oxidative damage is also incorporated in sustained stress response causing a series of chronic problems, such as cardiovascular and gastrointestinal diseases, immune dysfunction, and development of abnormal behaviors. In this review, the effects and mechanisms of dietary regulation strategies (e.g., antioxidants, anxiolytic agents, and probiotics) on relieving stress in pet dogs and cats are summarized and discussed. We aim to shed light on future studies in the field of pet food and nutrition.

Sigma-1 receptor: A potential target for the development of antidepressants

Though a great many of studies on the development of antidepressants for the therapy of major depression disorder (MDD) and the development of antidepressants have been carried out, there still lacks an efficient approach in clinical practice. The involvement of Sigma-1 receptor in the pathological process of MDD has been verified. In this review, recent research focusing on the role of Sigma-1 receptor in the etiology of MDD were summarized. Preclinical studies and clinical trials have found that stress induce the variation of Sigma-1 receptor in the blood, brain and heart. Dysfunction and absence of Sigma-1 receptor result in depressive-like behaviors in rodent animals. Agonists of Sigma-1 receptor show not only antidepressant-like activities but also therapeutical effects in complications of depression. The mechanisms underlying antidepressant-like effects of Sigma-1 receptor may include suppressing neuroinflammation, regulating neurotransmitters, ameliorating brain-derived neurotrophic factor and N-Methyl-D-Aspartate receptor, and alleviating the endoplasmic reticulum stress and mitochondria damage during stress. Therefore, Sigma-1 receptor represents a potential target for antidepressants development.

Chronic Stress in Bipolar Disorders Across the Different Clinical States: Roles of HPA Axis and Personality

INTRODUCTION

Chronic stress has been linked to the pathophysiology of bipolar disorder (BD); however, the underlying mechanism remains unclear. In BD patients, hypothalamic-pituitary-adrenal (HPA) axis activity is associated with stress. This study aimed to examine the relationship between HPA axis activity and BD symptoms in various clinical states, as well as how personality influences the process.

METHODS

This study investigated the differences in HPA axis activity among four BD states. We enrolled 813 BD patients in an 8-week longitudinal study to examine the relationship between HPA axis activity and symptom trajectories using dynamic temporal warping (DTW) analysis and an unsupervised machine learning technique. Furthermore, using mediation analyses, the relationship between the HPA axis, personality, and BD symptoms was investigated.

RESULTS

Analysis of variance (ANOVA) analysis showed that glucocorticoid cortisol (CORT) and adrenocorticotropin (ACTH) did not differ significantly among the four clinical states of BD. The DTW integrating clustering analysis revealed that the two clusters were optimal, with cluster 1 characterized by severe manic symptoms, which then improved, and cluster 2, characterized by milder manic severity, which also improved. The two clusters showed different ACTH levels (t = 2.289, p = 0.022), and logistic regression analysis revealed a slight positive association between ACTH levels and cluster 1. Furthermore, the mediation analysis indicated that ACTH influences curative efficacy via conscientiousness (βc =0.103, p=0.001).

DISCUSSION

In conclusion, we found that a higher level of ACTH is associated with severe manic symptoms, indicating a chronic stress response in BD patients. Additionally, the ACTH levels affect short-term BD curative efficacy via the mediation of conscientiousness, providing a psychotherapeutic strategy direction for BD.

Ketamine-induced neurotoxicity is mediated through endoplasmic reticulum stress in vitro in STHdhQ7/Q7 cells

Ketamine has traditionally been used as a dissociative anesthetic agent and more recently as a treatment for treatment-resistant depression. However, there is growing concern over the increased use of ketamine in recreational and therapeutic settings due to the potential neurotoxic effects. Recent studies have demonstrated that ketamine is cytotoxic in several cell types, such as fibroblasts, hepatocytes, uroepithelial cells, and adult induced pluripotent stem cells (iPSCs). Ketamine has been shown to dysregulate calcium signalling, increase reactive oxygen species (ROS) production, and impair mitochondrial function, ultimately leading to apoptosis. However, it is unclear whether endoplasmic reticulum (ER) stress plays a role in ketamine associated neurotoxicity in striatal neurons. Disruption to ER homeostasis can initiate ER-mediated cell death, which has been implicated in several neurodegenerative diseases. Thus, the purpose of this study was to determine whether ketamine's neurotoxic effects involve an ER stress-dependent pathway and to elucidate the underlying mechanisms involved in its neurotoxic effects. Mouse striatal cells were treated with various concentrations of ketamine (10 μM, 100 μM, 1 mM) or DMEM for 9-72 hrs. Cell viability was assessed using the MTT assay, and changes in gene expression of ER stress markers were evaluated using RT-qPCR. MTT results revealed that 1 mM ketamine decreased cell viability in striatal cells after 24 h of treatment. Gene expression studies complemented these findings such that ketamine upregulated pro-apoptotic ER stress markers, including X-box binding protein 1 (XBP1), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP) and downregulated pro-survival ER stress proteins such as GRP78, MANF and CDNF. Ketamine activated all three stress sensing pathways including PERK, IRE1, and ATF6. Taken together, our results show that ketamine-induced neurotoxicity is mediated through an ER stress-dependent apoptotic pathway.

Cellular Response to Unfolded Proteins in Depression

Despite many scientific studies on depression, there is no clear conception explaining the causes and mechanisms of depression development. Research conducted in recent years has shown that there is a strong relationship between depression and the endoplasmic reticulum (ER) stress. In order to restore ER homeostasis, the adaptive unfolded protein response (UPR) mechanism is activated. Research suggests that ER stress response pathways are continuously activated in patients with major depressive disorders (MDD). Therefore, it seems that the recommended drugs should reduce ER stress. A search is currently underway for drugs that will be both effective in reducing ER stress and relieving symptoms of depression.

Chronic stress and endothelial dysfunction: mechanisms, experimental challenges, and the way ahead

Although chronic stress is an important risk factor for cardiovascular diseases (CVD) onset, the underlying mechanisms driving such pathophysiological complications remain relatively unknown. Here, dysregulation of innate stress response systems and the effects of downstream mediators are strongly implicated, with the vascular endothelium emerging as a primary target of excessive glucocorticoid and catecholamine action. Therefore, this review article explores the development of stress-related endothelial dysfunction by focusing on the following: 1) assessing the phenomenon of stress and complexities surrounding this notion, 2) discussing mechanistic links between chronic stress and endothelial dysfunction, and 3) evaluating the utility of various preclinical models currently employed to study mechanisms underlying the onset of stress-mediated complications such as endothelial dysfunction. The data reveal that preclinical models play an important role in our efforts to gain an increased understanding of mechanisms underlying stress-mediated endothelial dysfunction. It is our understanding that this provides a good foundation going forward, and we propose that further efforts should be made to 1) more clearly define the concept of stress and 2) standardize protocols of animal models with specific guidelines to better indicate the mental complications that are simulated.

Antidepressant effects of 3-(3,4-methylenedioxy-5-trifluoromethyl phenyl)-2E-propenoic acid isobutyl amide involve TSPO-mediated mitophagy signalling pathway

Piper laetispicum C. DC is one of the Chinese herbal medicines used for alleviating depressive disorders. G11-5 [3-(3, 4-methylenedioxy-5-trifluoromethyl phenyl)-2E-propenoic acid isobutyl amide] is synthesized based on the chemical structure of an active integrant of Piper laetispicum C. DC. The present study assessed the antidepressant effect of G11-5 and investigated the underlying mechanism with learned helplessness (LH) and social defeat stress (SDS) mice model of depression. In the LH model, mice were exposed to 60 inescapable electric shocks once a day for three consecutive days followed by 2-week drug administration and helpless behaviour assessment. In the SDS model, mice were subjected to repeated social defeat by an aggressive CD-1 mouse once a day for consecutive 10 days. Following oral administration for 2 weeks, the mice were subjected to a series of behavioural tests including social interaction test. G11-5 significantly decreased the number of escape failures induced by LH paradigm, meanwhile increased the social interaction ratio and shortened the immobility time in forced swimming test for the SDS-exposed mice, suggesting remarkable antidepressant effect. Moreover, G11-5 ameliorated the changes in mitophagy-related proteins induced by two stress exposures and restored retrograde axonal transport and neurotransmitter release. Our findings suggested that G11-5 exhibited an obvious antidepressant through TSPO-mediated mitophagy pathway.

Hydrogen Sulfide and Endoplasmic Reticulum Stress: A Potential Therapeutic Target for Central Nervous System Degeneration Diseases

There are three members of the endogenous gas transmitter family. The first two are nitric oxide and carbon monoxide, and the third newly added member is hydrogen sulfide (H₂S). They all have similar functions: relaxing blood vessels, smoothing muscles, and getting involved in the regulation of neuronal excitation, learning, and memory. The cystathionine β-synthase (CBS), 3-mercaptopyruvate sulfur transferase acts together with cysteine aminotransferase (3-MST/CAT), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfur transferase with D-amino acid oxidase (3-MST/DAO) pathways are involved in the enzymatic production of H₂S. More and more researches focus on the role of H₂S in the central nervous system (CNS), and H₂S plays a significant function in neuroprotection processes, regulating the function of the nervous system as a signaling molecule in the CNS. Endoplasmic reticulum stress (ERS) and protein misfolding in its mechanism are related to neurodegenerative diseases. H₂S exhibits a wide variety of cytoprotective and physiological functions in the CNS degenerative diseases by regulating ERS. This review summarized on the neuroprotective effect of H₂S for ERS played in several CNS diseases including Alzheimer’s disease, Parkinson’s disease, and depression disorder, and discussed the corresponding possible signaling pathways or mechanisms as well.

Mitochondria, endoplasmic reticulum and innate immune dysfunction in mood disorders: Do Mitochondria-Associated Membranes (MAMs) play a role?

Mood disorders like major depression and bipolar disorder (BD) are among the most prevalent forms of mental illness. Current knowledge of the neurobiology and pathophysiology of these disorders is still modest and clear biological markers are still missing. Thus, a better understanding of the underlying pathophysiological mechanisms to identify potential therapeutic targets is a prerequisite for the design of new drugs as well as to develop biomarkers that help in a more accurate and earlier diagnosis. Multiple pieces of evidence including genetic and neuro-imaging studies suggest that mood disorders are associated with abnormalities in endoplasmic-reticulum (ER)-related stress responses, mitochondrial function and calcium signalling. Furthermore, deregulation of the innate immune response has been described in patients diagnosed with mood disorders, including depression and BD. These disease-related events are associated with functions localized to a subdomain of the ER, known as Mitochondria-Associated Membranes (MAMs), which are lipid rafts-like domains that connect mitochondria and ER, both physically and biochemically. This review will outline the current understanding of the role of mitochondria and ER dysfunction under pathological brain conditions, particularly in major depressive disorder (MDD) and BD, that support the hypothesis that MAMs can act in these mood disorders as the link connecting ER-related stress response and mitochondrial impairment, as well as a mechanisms behind sterile inflammation arising from deregulation of innate immune responses. The role of MAMs in the pathophysiology of these pathologies and its potential relevance as a potential therapeutic target will be discussed.

Role of endoplasmic reticulum stress in depression (Review)

Depression is a devastating mood disorder that causes profound disability worldwide. Despite the increasing number of antidepressant medications available, the treatment options for depression are limited. Therefore, understanding the etiology and pathophysiology of depression, and exploiting potential novel agents to treat and prevent this disorder are imperative. Endoplasmic reticulum (ER) stress activates the unfolded protein response and mediates the pathogenesis of psychiatric diseases, including depression. Emerging evidence in human and animal models suggests an intriguing link between ER stress and depression. The ER serves as an important subcellular organelle for the synthesis, folding, modification, and transport of proteins, a process that is highly developed in neuronal cells. Perturbations of ER homeostasis lead to ER stress, and ER stress helps to restore the normal ER function by restoring the protein-folding capacity of the ER. This biological defense mechanism is imperative to prevent the disease. However, excessive or persistent ER stress eventually causes cell death. If the damage occurs in the hippocampus, the amygdala and striatum and other areas of the neurons will be involved in the development of depression. In this review article, we explore how ER stress might have an important role in the pathophysiology of depression and how different drugs affect depression through ER stress.

Linking unfolded protein response to inflammation and depression: potential pathologic and therapeutic implications

Depression is a devastating mental disorder that affects millions of people worldwide. Inflammation has been shown to be a key factor involved in the underlying pathophysiology of depression and has been shown in a substantial proportion of cases of depression. Changes attributed with morphological deformities and immunomodulation in susceptible regions of the depressed brain raised the possibility of altered cellular homeostasis transduced by the intracellular stress response. How emotional stressors can lead to an inflamed brain that directly affects physiology and activity is yet to be fully understood. The unfolded protein response (UPR) has been shown to be active in both models of depression as well as in postmortem brain of depressed individuals. The UPR is the cellular response to stress which results in misfolded proteins. Interestingly, UPR activation is directly linked to both inflammatory cytokine production and Toll-like receptor (TLR) expression. The TLRs are part of the innate immune response which typically reacts to "classic invasions" such as bacteria or viruses as well as trauma. TLRs have also been shown to be upregulated in depression, thus solidifying the connection between inflammation and depression. In this review, we aim to tie the UPR-TLR response and depression, and describe the implications of such an association. We also propose future directions for their role in treatment for depression.

Elevated heat shock proteins in bipolar disorder patients with hypothalamic pituitary adrenal axis dysfunction

BACKGROUND

Heat shock proteins (HSP) might be useful as biomarkers for bipolar disorder (BD) which would be clinically valuable since no reliable biomarker for BD has so far been identified. The purpose of this study was to assess the heat shock proteins CPN10, CPN60, and CPN70 as potential biomarkers of BD.

METHODS

The study included 100 BD patients recruited from a hospital during 2012 and 2013. The study also included 94 healthy controls. Among the BD patients, 33 had abnormal hypothalamic-pituitary-adrenal (HPA) axis activity. Blood samples were obtained from the patients and controls. The chemiluminescence method, mass spectrometry, and flow cytometry were used for analysis.

RESULTS

The BD patients compared with the controls had a significantly lower level of CPN10 and significantly higher levels of CPN60 and CPN70. The BD patients with abnormal HPA axis activity had a significantly lower level of CPN60 compared with the normal HPA axis activity group of BD patients. The CPN60 level significantly inversely correlated with adrenocorticotropic hormone (ACTH) level in patients with bipolar depression and in patients with bipolar hypomania, and CPN70 significantly correlated with ACTH level in patients with bipolar depression and hypomania.

CONCLUSIONS

Our findings suggest that the heat shock proteins CPN10, CPN60, and CPN70 might have potential as biomarkers for BD and CPN60 blood level might distinguish patients with abnormal HPA axis activity from those with normal HPA axis activity.

Synaptic proteomics as a means to identify the molecular basis of mental illness: Are we getting there?

Synapses are centrally involved in many brain disorders, particularly in psychiatric and neurodevelopmental ones. However, our current understanding of the proteomic alterations affecting synaptic performance in the majority of mental illnesses is limited. As a result, novel pharmacotherapies with improved neurological efficacy have been scarce over the past decades. The main goal of synaptic proteomics in the context of mental illnesses is to identify dysregulated molecular mechanisms underlying these conditions. Here we reviewed and performed a meta-analysis of previous neuroproteomic research to identify proteins that may be consistently dysregulated in one or several mental disorders. Notably, we found very few proteins reproducibly altered among independent experiments for any given condition or between conditions, indicating that we are still far from identifying key pathophysiological mechanisms of mental illness. We suggest that future research in the field will require higher levels of standardization and larger-scale experiments to address the challenge posed by biological and methodological variability. We strongly believe that more resources should be placed in this field as the need to identify the molecular roots of mental illnesses is highly pressing.

Integrative Proteomics-Metabolomics Strategy for Pathological Mechanism of Vascular Depression Mouse Model

Vascular depression (VD), a subtype of depression, is caused by vascular diseases or cerebrovascular risk factors. Recently, the proportion of VD patients has increased significantly, which severely affects their quality of life. However, the current pathogenesis of VD has not yet been fully understood, and the basic research is not adequate. In this study, on the basis of the combination of LC-MS-based proteomics and metabolomics, we aimed to establish a protein metabolism regulatory network in a murine VD model to elucidate a more comprehensive impact of VD on organisms. We detected 44 metabolites and 304 proteins with different levels in the hippocampus samples from VD mice using a combination of metabolomic and proteomics analyses with an isobaric tags for relative and absolute quantification (iTRAQ) method. We constructed a protein-to-metabolic regulatory network by correlating and integrating the differential metabolites and proteins using ingenuity pathway analysis. Then we quantitatively validated the levels of the bimolecules shown in the bioinformatics analysis using LC-MS/MS and Western blotting. Validation results suggested changes in the regulation of neuroplasticity, transport of neurotransmitters, neuronal cell proliferation and apoptosis, and disorders of amino acids, lipids and energy metabolism. These proteins and metabolites involved in these dis-regulated pathways will provide a more targeted and credible direction to study the mechanism of VD. Therefore, this paper presents an approach and strategy that was applied in integrative proteomics and metabolomics for research and screening potential targets and biomarkers of VD, which could be more precise and credible in a field lacking adequate basic research.

Recent advances in applying mass spectrometry and systems biology to determine brain dynamics

INTRODUCTION

Neurological disorders encompass various pathologies which disrupt normal brain physiology and function. Poor understanding of their underlying molecular mechanisms and their societal burden argues for the necessity of novel prevention strategies, early diagnostic techniques and alternative treatment options to reduce the scale of their expected increase. Areas covered: This review scrutinizes mass spectrometry based approaches used to investigate brain dynamics in various conditions, including neurodegenerative and neuropsychiatric disorders. Different proteomics workflows for isolation/enrichment of specific cell populations or brain regions, sample processing; mass spectrometry technologies, for differential proteome quantitation, analysis of post-translational modifications and imaging approaches in the brain are critically deliberated. Future directions, including analysis of cellular sub-compartments, targeted MS platforms (selected/parallel reaction monitoring) and use of mass cytometry are also discussed. Expert commentary: Here, we summarize and evaluate current mass spectrometry based approaches for determining brain dynamics in health and diseases states, with a focus on neurological disorders. Furthermore, we provide insight on current trends and new MS technologies with potential to improve this analysis.

Hydrogen Sulfide Inhibits Chronic Unpredictable Mild Stress-Induced Depressive-Like Behavior by Upregulation of Sirt-1: Involvement in Suppression of Hippocampal Endoplasmic Reticulum Stress

BACKGROUND

Hydrogen sulfide (H2S) is a crucial signaling molecule with a wide range of physiological functions. Previously, we confirmed that stress-induced depression is accompanied with disturbance of H2S generation in hippocampus. The present work attempted to investigate the inhibitory effect of H2S on chronic unpredictable mild stress-induced depressive-like behaviors and the underlying mechanism.

METHODS

We established the rat model of chronic unpredictable mild stress to simulate depression. Open field test, forced swim test, and tail suspension test were used to assess depressive-like behaviors. The expression of Sirt-1 and three marked proteins related to endoplasmic reticulum stress (GRP-78, CHOP, and cleaved caspase-12) were detected by western blot.

RESULTS

We found that chronic unpredictable mild stress-exposed rats exhibit depression-like behavior responses, including significantly increased immobility time in the forced swim test and tail suspension test, and decreased climbing time and swimming time in the forced swim test. In parallel, chronic unpredictable mild stress-exposed rats showed elevated levels of hippocampal endoplasmic reticulum stress and reduced levels of Sirt-1. However, NaHS (a donor of H2S) not only alleviated chronic unpredictable mild stress-induced depressive-like behaviors and hippocampal endoplasmic reticulum stress, but it also increased the expression of hippocampal Sirt-1 in chronic unpredictable mild stress-exposed rats. Furthermore, Sirtinol, an inhibitor of Sirt-1, reversed the protective effects of H2S against chronic unpredictable mild stress-induced depression-like behaviors and hippocampal endoplasmic reticulum stress.

CONCLUSION

These results demonstrated that H2S has an antidepressant potential, and the underlying mechanism is involved in the inhibition of hippocampal endoplasmic reticulum stress by upregulation of Sirt-1 in hippocampus. These findings identify H2S as a novel therapeutic target for depression.

The exercise-glucocorticoid paradox: How exercise is beneficial to cognition, mood, and the brain while increasing glucocorticoid levels

Exercise is known to have beneficial effects on cognition, mood, and the brain. However, exercise also activates the hypothalamic-pituitary-adrenal axis and increases levels of the glucocorticoid cortisol (CORT). CORT, also known as the "stress hormone," is considered a mediator between chronic stress and depression and to link various cognitive deficits. Here, we review the evidence that shows that while both chronic stress and exercise elevate basal CORT levels leading to increased secretion of CORT, the former is detrimental to cognition/memory, mood/stress coping, and brain plasticity, while the latter is beneficial. We propose three preliminary answers to the exercise-CORT paradox. Importantly, the elevated CORT, through glucocorticoid receptors, functions to elevate dopamine in the medial prefrontal cortex under chronic exercise but not chronic stress, and the medial prefrontal dopamine is essential for active coping. Future inquiries may provide further insights to promote our understanding of this paradox.

Neuroprotective, Neurotrophic and Anti-oxidative Role of Bacopa monnieri on CUS Induced Model of Depression in Rat

Major depression is a life threatening neuropsychiatric disorder that produces mental illness and major cause of morbidity. The present study was conducted to evaluate the neuroprotective, neurotrophic and antioxidant potential of Bacopa monnieri extract (BME) on chronic unpredictable stress (CUS) induced behavioral depression in rats. Behavioral tests were carried out for investigation of antidepressant like effects of BME, and potential mechanism was assessed by determining neurotrophin level and hippocampal neurogenesis. Depressive-like behavior was assessed by shuttle-box escape test, forced swim test and tail suspension test. Effect of BME on hypothalamic-pituitary-adrenal (HPA) axis was evaluated by measuring the plasma level of adrenocorticotropic hormone (ACTH) and corticosterone. The expression of brain derived neurotrophic factor (BDNF), neuronal marker doublecortin (DCX) in the hippocampus were measured and hippocampal neurogenesis was investigated by 5-bromo-2-deoxyuridine/neuronal nuclei (BrdU/NeuN). In addition, effects of BME on oxidative stress markers were also measured in the hippocampus of CUS exposed rats. The results indicated that BME significantly able to attenuate the depressive-like behaviors, normalized the levels of ACTH, corticosterone, and up-regulate the expression of BDNF, DCX and BrdU/NeuN in CUS induced rats compared to BME treated rats. It is also found that BME significantly increased the activity of antioxidant enzymes on CUS induced rats. These findings revealed that BME exerted neuroprotective effects possibly by promoting hippocampal neurogenesis with elevation of BDNF level and antioxidant defense against oxidative stress.

Alteration of Energy Metabolism and Antioxidative Processing in the Hippocampus of Rats Reared in Long-Term Environmental Enrichment

Environmental enrichment (EE) is a typical experimental method that promotes levels of novelty and complexity that enhance experience-dependent neuroplasticity and cognitive behavior function in laboratory animals. Early EE is associated with resilience in the face of later-life challenges. Since increased synaptic activity enhances endogenous neuronal antioxidant defenses, we hypothesized that long-term EE beginning at an early stage may alter the levels of oxidative stress. We investigated global protein expression and oxidative stress in hippocampal proteins from rats nurtured for a 6-month EE beginning in the prenatal period. The analysis of protein expression was carried out using 2-dimensional gel electrophoresis with matrix-associated laser desorption ionization time-of-flight mass spectrometry. Proteins with altered expression were involved in energy metabolism (phosphoglycerate mutase 1, α-enolase isoform 1, adenylate kinase 1, and triose phosphate isomerase) and antioxidant enzymes (superoxide dismutase 1, glutathione S-transferase ω type 1, peroxiredoxin 5, DJ-1, and glial maturation factor β). Using Western blot assays, some of the proteins with altered expression and NADPH oxidase 2 were confirmed to be decreased. Further confirmation was demonstrated with attenuated expression of 7,8-dihydro-8-oxo-deoxyguanine, a DNA oxidative stress marker, in the hippocampus of EE group rats. Our data demonstrate that a long-term EE program beginning in the prenatal and early postnatal phase of development modulates energy metabolism and reduced oxidant stress possibly through enhanced synaptic activity. We provide evidence that EE can be developed as a tool to protect the brain from oxidative stress-induced injury.

PGC-1α/ERRα-Sirt3 Pathway Regulates DAergic Neuronal Death by Directly Deacetylating SOD2 and ATP Synthase β

AIMS

Parkinson's disease (PD) heavily affects humans and little is known about its cause and pathogenesis. Sirtuin 3 (Sirt3) plays a key role in regulating mitochondrial dysfunction, which is the main cause of DAergic neuronal loss in PD. We investigated the mechanisms of neuroprotective role of Sirt3 in DAergic neuronal survival.

RESULTS

Sirt3 was reduced in 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP)-treated neurons with its overexpression being neuroprotective. We identified that Sirt3 interacted with manganese superoxide dismutase (SOD2) and adenosine triphosphate (ATP) synthase β and modulated their activities by deacetylating SOD2 (K130) and ATP synthase β (K485) to prevent reactive oxygen species accumulation and ATP depletion, and to alleviate DAergic neuronal death upon MPTP treatment. Peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) interacted with estrogen-related receptor alpha (ERRα) that bound to the Sirt3 promoter as its transcription factor to regulate Sirt3 expression and DAergic neuronal death. In the mouse midbrain, MPTP administration led to the loss of PGC-1α and Sirt3, high acetylation level of SOD2 and ATP synthase β, and the specific loss of DAergic neurons, while Sirt3 overexpression could protect against DAergic neuronal loss. Sirt3 knockout mice exhibited more sensitive and more DAergic neuronal loss to MPTP treatment.

INNOVATION

The study provides new insights into a critical PGC-1α/ERRα-Sirt3 pathway, linking regulation of mitochondrial protein acetylation and DAergic neuronal death in PD pathogenesis, which provide a potential therapeutic strategy and target in PD treatment.

CONCLUSION

These results provide a vital PGC-1α/ERRα-Sirt3 pathway that protects against DAergic neuronal death by directly deacetylating SOD2 (K130) and ATP synthase β (K485) in PD.

Lactulose enhances neuroplasticity to improve cognitive function in early hepatic encephalopathy

Lactulose is known to improve cognitive function in patients with early hepatic encephalopathy; however, the underlying mechanism remains poorly understood. In the present study, we investigated the behavioral and neurochemical effects of lactulose in a rat model of early hepatic encephalopathy induced by carbon tetrachloride. Immunohistochemistry showed that lactulose treatment promoted neurogenesis and increased the number of neurons and astrocytes in the hippocampus. Moreover, lactulose-treated rats showed shorter escape latencies than model rats in the Morris water maze, indicating that lactulose improved the cognitive impairments caused by hepatic encephalopathy. The present findings suggest that lactulose effectively improves cognitive function by enhancing neuroplasticity in a rat model of early hepatic encephalopathy.

The contribution of proteomic studies in humans, animal models, and after antidepressant treatments to investigate the molecular neurobiology of major depression

The neurobiological basis of major depressive disorder (MDD) is only partially understood. The proposed hypotheses postulate dysregulations of monoaminergic and other neurotransmitter pathways, impaired stress responses, insufficient neurogenetic and neurotrophic processes generating maladaptive neuroplasticity, inappropriate inflammatory and metabolic responses. Proteomic approaches can provide useful contributions to the investigation of the molecular neurobiology of MDD due to their open-ended nature. Studies performed in brain regions of MDD patients which had received antidepressant (AD) treatment showed that affected proteins mainly belonged to energy pathways, transport of molecules, signaling, and synaptic transmission. Studies performed in animal models offer the advantage of more controlled experimental conditions at the expense of potential loss in relevance. The design of proteomic investigations included experiments carried out in MDD models, in naive animals treated with ADs, and in animal models subjected to AD treatments. A comparison of results suggested an overlap of several modulated pathways between MDD patients and animal models. Examples include the regulation of energy metabolism, especially oxidative phosphorylation and glycolysis, signal transduction pathways, including calcium-calmodulin kinase II, synaptic proteins, and cytoskeletal proteins. Nevertheless, the paucity of studies performed in human brains requires additional studies to confirm the correspondence.

Elevated systemic expression of ER stress related genes is associated with stress-related mental disorders in the Detroit Neighborhood Health Study

BACKGROUND

The role of endoplasmic reticulum (ER) stress response in mental illness is not well understood. Human studies and animal models of depression show elevated brain ER stress response. In addition, some ER stress associated disorders (e.g. cardiovascular disease) show higher rates of depression compared to the general population, raising the possibility that ER stress response contributes to depression risk. It remains unknown, however, if ER stress response is present among individuals suffering from other stress-related mental illness, and whether such a response would be evident in a non-clinical sample. This study tests for systemic changes in ER stress response associated with Major Depressive Disorder (MDD) or post-traumatic stress disorder (PTSD) among community-dwelling individuals.

METHODS

We analyzed expression of BiP, EDEM1, CHOP, and XBP1, the major indicators of ER stress response, with real-time PCR in leukocyte-derived RNA samples from 86 participants of the Detroit Neighborhood Health Study. Participants were selected based on the presence of either past year MDD or past year PTSD; controls were age and sex matched.

RESULTS

Relative to controls, MDD is associated with a 1.34-fold increase in BiP (P=0.004), 1.35-fold increase in EDEM1 (P=0.001), 1.68-fold increase in CHOP (P=0.002), and 1.60-fold increase in XBP1 (P=0.004). These results remained significant after correction for multiple testing. In contrast, PTSD is associated with a 1.27-fold increase in EDEM1 expression only (P=0.027), a result that is attenuated to non-significance following adjustment for multiple testing; however, a subsample of participants with past month PTSD showed elevated expression of BiP and EDEM1 (uncorrected P value 0.049 and 0.017, respectively).

CONCLUSIONS

These data indicate systemic and persistent activation of the ER stress response pathway in MDD among community-dwelling individuals. Systemic activation of the ER stress response may also occur in PTSD among persons with more recent symptoms.

A terrified-sound stress induced proteomic changes in adult male rat hippocampus

In this study, we investigated the biochemical mechanisms in the adult rat hippocampus underlying the relationship between a terrified-sound induced psychological stress and spatial learning. Adult male rats were exposed to a terrified-sound stress, and the Morris water maze (MWM) has been used to evaluate changes in spatial learning and memory. The protein expression profile of the hippocampus was examined using two-dimensional gel electrophoresis (2DE), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and bioinformatics analysis. The data from the MWM tests suggested that a terrified-sound stress improved spatial learning. The proteomic analysis revealed that the expression of 52 proteins was down-regulated, while that of 35 proteins were up-regulated, in the hippocampus of the stressed rats. We identified and validated six of the most significant differentially expressed proteins that demonstrated the greatest stress-induced changes. Our study provides the first evidence that a terrified-sound stress improves spatial learning in rats, and that the enhanced spatial learning coincides with changes in protein expression in rat hippocampus.

Motor coordination dysfunction induced by gold nanorods core/silver shell nanostructures in mice: disruption in mitochondrial transport and neurotransmitter release

The risk of exposure to silver nanoparticles (AgNPs) is becoming increasingly widespread and causes great concern.

Dynamic proteomics of nucleus accumbens in response to acute psychological stress in environmentally enriched and isolated rats

Our prior research has shown that environmental enrichment (i.e. rats reared in an environment with novel objects, social contact with conspecifics) produces a protective antidepressant-like phenotype in rats and decreases neurobiological effects of acute psychological stress. Although CREB activity has been identified as a major player, the downstream molecular mechanisms remain largely unexplored. Thus, the current study investigates proteomic differences in the accumbens of rats raised in an enriched condition (EC) versus those raised in an isolated control condition (IC) under basal conditions and after 30 min of acute restraint stress. Results showed that under basal conditions, EC rats generally expressed less mitochondria-related proteins, particularly those involved in TCA cycle and electron transport compared to IC rats. After 30 min of acute stress, EC rats displayed increased expression of energy metabolism enzymes (among others) while IC rats exhibited decreased expression of similar proteins. Further, network and pathway analyses also identified links to AKT signaling proteins, 14-3-3 family proteins, heat-shock proteins, and ubiquitin-interacting proteins. The protein ENO1 showed marked differential expression and regulation; EC rats expressed higher levels under basal conditions that increased subsequent to stress, while the basal IC expression was lower and decreased further still after stress. The results of this study define differential protein expression in a protective rat model for major depression and additionally identify a dynamic and coordinated differential response to acute stress between the two groups. These results provide new avenues for exploration of the molecular determinants of depression and the response to acute stress.

Essential oil of Perilla frutescens-induced change in hippocampal expression of brain-derived neurotrophic factor in chronic unpredictable mild stress in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Perilla frutescens (Perilla leaf), a traditional Chinese medicinal herb, has been used for centuries to treat various conditions including depression. A previous study of the authors demonstrated that essential oil of Perilla frutescens (EOPF) attenuated the depressive-like behavior in mice.

AIM OF THE STUDY

This study was undertaken to explore the dynamic change of behaviors and brain-derived neurotrophic factor (BDNF) expression induced by chronic unpredictable mild stress (CUMS), and improved by EOPF.

MATERIALS AND METHODS

Four separate CUMS experimental groups (1-week, 2-week, 3-week and 4-week treatment) were treated with EOPF (3 mg/kg and 6 mg/kg, p.o.) or fluoxetine (20 mg/kg, p.o.), followed by sucrose preference, locomotor activity, immobility and hippocampal BDNF measurement.

RESULTS

EOPF, as well as fluoxetine, restored the CUMS-induced decreased sucrose preference and increased immobility time, without affecting body weight gain and locomotor activity. Furthermore, CUMS (3 or 4-week) produced a reduction in both BDNF mRNA and protein expression in the hippocampus, which were ameliorated by EOPF (4-week) and fluoxetine (3 or 4-week) treatment.

CONCLUSION

These results presented here show that BDNF is expressed depending on length of CUMS procedure and EOPF administration. And this study might contribute to the underlying reason for the slow onset of antidepressant activity in clinic.

Nobiletin Ameliorates the Deficits in Hippocampal BDNF, TrkB, and Synapsin I Induced by Chronic Unpredictable Mild Stress

Background. Our previous study has demonstrated that nobiletin could reverse the behavioral alterations in stressed mice. However, the relation of its antidepressant-like action with neurotrophic molecular expression remains unknown. This study aimed to explore the antidepressant-like mechanism of nobiletin related to the neurotrophic system in rats exposed to chronic unpredictable mild stress (CUMS). Methods. Depressive-like anhedonia (assessed by sucrose preference) and serum corticosterone secretion were evaluated in the CUMS, followed by brain-derived neurotrophic factor (BDNF), its tropomyosin-related kinase receptor B (TrkB), and the downstream target synapsin I expressions in the hippocampus. Results. Anhedonia, which occurred within week 2, was rapidly ameliorated by nobiletin. While fluoxetine needed additional 2 weeks to improve the anhedonia. In addition, nobiletin administration for 5 weeks significantly ameliorated CUMS-induced increase in serum corticosterone levels. Furthermore, we also found that CUMS-induced deficits of hippocampal BDNF, TrkB, and synapsin I were ameliorated by nobiletin. Conclusions. Taken together, these findings suggest that nobiletin produces rapidly acting antidepressant-like responses in the CUMS and imply that BDNF-TrkB pathway may play an important role in the antidepressant-like effect of nobiletin.