Depression: Biological markers and treatment

Insights for the Next Generation of Ketamine for the Treatment of Depressive Disorder

Treatment-resistant depression responds quickly to ketamine. As an N-methyl-d-aspartate receptor (NMDAR) antagonist, ketamine may affect prefrontal cortex (PFC) neurons. Recent investigations reveal that the (R)-enantiomer is the most effective and least abuseable antidepressant. The Food and Drug Administration approves only the (S)-enantiomer for medical usage. (2R,6R)-Hydroxynorketamine (HNK) inhibits mGlu2, linked to a Gi, in presynaptic glutamatergic neurons, increasing brain-derived neurotrophic factor (BDNF) release, which autocrinely activates Tropomyosin receptor kinase B (TrkB) and promotes synaptogenesis. Ketamine, originally an anesthetic, has garnered attention for its many pharmacological effects, including its potential as a rapid-acting antidepressant and recreational use. In this Perspective, we explore the synthesis, pharmacology, metabolism, and effects of ketamine and its metabolites in animal and human studies to explain the difference in the biological activity between the enantiomers.

Brain region-specific roles of brain-derived neurotrophic factor in social stress-induced depressive-like behavior

Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response. Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region-specific, particularly involving the corticolimbic system, including the ventral tegmental area, nucleus accumbens, prefrontal cortex, amygdala, and hippocampus. Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology. In this review, we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression. We focused on associated molecular pathways and neural circuits, with special attention to the brain-derived neurotrophic factor-tropomyosin receptor kinase B signaling pathway and the ventral tegmental area-nucleus accumbens dopamine circuit. We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature, severity, and duration of stress, especially in the above-mentioned brain regions of the corticolimbic system. Therefore, BDNF might be a biological indicator regulating stress-related processes in various brain regions.

Chronic prostatitis/chronic pelvic pain syndrome induces metabolomic changes in expressed prostatic secretions and plasma

ABSTRACT

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a complex disease that is often accompanied by mental health disorders. However, the potential mechanisms underlying the heterogeneous clinical presentation of CP/CPPS remain uncertain. This study analyzed widely targeted metabolomic data of expressed prostatic secretions (EPS) and plasma to reveal the underlying pathological mechanisms of CP/CPPS. A total of 24 CP/CPPS patients from The Second Nanning People's Hospital (Nanning, China), and 35 asymptomatic control individuals from First Affiliated Hospital of Guangxi Medical University (Nanning, China) were enrolled. The indicators related to CP/CPPS and psychiatric symptoms were recorded. Differential analysis, coexpression network analysis, and correlation analysis were performed to identify metabolites that were specifically altered in patients and associated with various phenotypes of CP/CPPS. The crucial links between EPS and plasma were further investigated. The metabolomic data of EPS from CP/CPPS patients were significantly different from those from control individuals. Pathway analysis revealed dysregulation of amino acid metabolism, lipid metabolism, and the citrate cycle in EPS. The tryptophan metabolic pathway was found to be the most significantly altered pathway associated with distinct CP/CPPS phenotypes. Moreover, the dysregulation of tryptophan and tyrosine metabolism and elevation of oxidative stress-related metabolites in plasma were found to effectively elucidate the development of depression in CP/CPPS. Overall, metabolomic alterations in the EPS and plasma of patients were primarily associated with oxidative damage, energy metabolism abnormalities, neurological impairment, and immune dysregulation. These alterations may be associated with chronic pain, voiding symptoms, reduced fertility, and depression in CP/CPPS. This study provides a local-global perspective for understanding the pathological mechanisms of CP/CPPS and offers potential diagnostic and therapeutic targets.

Network analysis of depressive symptoms and C-reactive protein levels in major depressive disorder

BACKGROUND

C-reactive protein (CRP) levels have been implicated in the severity and symptomatology of major depressive disorder (MDD). The aim of this study was to explore the structure of depressive symptoms in patients with MDD according to different groups of CRP levels using network analysis.

METHODS

The study included 864 individuals (mean age = 54.05, 67.48 % male) diagnosed with MDD from the 2015-2020 National Health and Nutrition Examination Survey (NHANES). Analyses examined how depressive symptoms and CRP level were related to each other, and how the network structure of depressive symptoms differed across groups with different CRP levels.

RESULTS

A direct positive correlation was observed between CRP levels and specific depressive symptoms (e.g., appetite change, energy loss, and feelings of worthlessness). Moreover, there was a stronger correlation between depressive symptoms in the medium CRP and high CRP groups compared to the low CRP group. Furthermore, it was observed that there were notable structural differences between the high-CRP and moderate-CRP groups.

LIMITATIONS

The study is based on cross-sectional data, which precludes the drawing of causal conclusions. Furthermore, it does not take into account confounding factors such as body mass index (BMI) and lifestyle.

CONCLUSIONS

The findings underscore the pivotal role of CRP as a marker of the severity of depressive symptoms. Routine CRP level testing and anti-inflammatory therapies may be beneficial for depressed patients with elevated CRP levels in clinical practice.

Uncovering the effects and mechanisms of tea and its components on depression, anxiety, and sleep disorders: A comprehensive review

Depression, anxiety and sleep disorders are prevalent psychiatric conditions worldwide, significantly impacting the physical and mental well-being of individuals. The treatment of these conditions poses various challenges, including limited efficacy and potential side effects. Tea, a globally recognized healthful beverage, contains a variety of active compounds. Studies have shown that consuming tea or ingesting its certain active ingredients have a beneficial impact on the mental health issues mentioned above. While the effects of tea on physical health are well-documented, there remains a gap in our systematic understanding of its impact on mental health. This article offers a thorough overview of animal, clinical, and epidemiological studies examining tea and its components in the treatment of depression, anxiety, and sleep disorders, and summarizes the associated molecular mechanisms. The active ingredients in tea, including L-theanine, γ-aminobutyric acid (GABA), arginine, catechins, theaflavins, caffeine, theacrine, and several volatile compounds, may help improve depression, anxiety, and sleep disorders. The underlying molecular mechanisms involve the regulation of neurotransmitters, including monoamines, GABA, and brain-derived neurotrophic factor (BDNF), as well as the suppression of oxidative stress and inflammation. Additionally, these ingredients may influence the microbiota-gut-brain (MGB) axis and the hypothalamic-pituitary-adrenal (HPA) axis. This review provides valuable insights into the effects and mechanisms by which tea and its components regulate depression, anxiety, and sleep disorders, laying the groundwork for further research into relevant mechanisms and the development of tea-based mental health products.

Study on the Mechanism of Dictyophora duplicata Polysaccharide in Reducing Depression-like Behavior in Mice

BACKGROUND/OBJECTIVES

Depression is a prevalent worldwide mental health disorder that inflicts significant harm to individuals and society. Dictyophora duplicata is an edible fungus that contains a variety of nutrients, including polysaccharides. This study aims to investigate the monosaccharide composition and molecular weight of the Dictyophora duplicata polysaccharide (DDP-B1), followed by an exploration of its antidepressant effects in chronic unpredictable mild stress (CUMS) mice.

METHODS

Dictyophora duplicata was purified using a DEAE-52 column and an S-400 column to obtain DDP-B1. The monosaccharide composition and molecular weight of DDP-B1 were investigated via high-performance gel permeation chromatograph. Six-week-old C57BL/6 male mice were utilized for the CUMS modeling to evaluate the antidepressant efficacy of DDP-B1. Fluoxetine served as the positive control group. The depressive-like behaviors and brain pathology of mice were evaluated. Immunofluorescence (IF) staining, metabolomics analysis, and western blot were employed to further investigate the underlying mechanisms.

RESULTS

DDP-B1 significantly alleviated the depression-like behavior of CUMS mice and increased the expression of SYN and PSD-95 in the mice's brains, which was further validated by western blot. Metabolomics analysis indicated a reduction in serum glutamate in CUMS mice following DDP-B1 treatment. Moreover, DDP-B1 treatment led to an increase in levels of GABAAR, BDNF, p-TrkB and p-p70S6K.

CONCLUSIONS

DDP-B1 regulated abnormalities in the glutamatergic system, subsequently activated the BDNF-TrkB-mTOR pathway and mitigated the pathological manifestations of CUMS mice. This study validated the potential of DDP-B1 as an antidepressant medication and established a theoretical foundation for the development of fungi with similar properties.

More adverse childhood experiences are associated with increased social thinning and severe psychological distress

Adverse childhood experiences have been linked to psychopathology due to reduced social networks or social thinning. However, evidence of the temporal associations between adverse childhood experiences, social networks, and psychopathology was lacking, as few studies assessed social networks repeatedly. Further, their underlying neurocognitive and biological mechanisms related to hypervigilance and inflammation remain unclear. This study aimed to clarify these associations using a three-wave population-based cohort study during the COVID-19 pandemic (n = 465), where we leveraged repeated social network assessments. Self-reported questionnaires assessed adverse childhood experiences, social network size and diversity, psychological distress, and hypervigilance regarding COVID-19. Blood tests were conducted to measure inflammation markers. Individuals with more adverse childhood experiences demonstrated lesser increases in their social networks than those without adverse childhood experiences. Decreased network sizes were associated with severe psychological distress, but this association did not remain after adjusting for baseline distress. On the other hand, reduced network diversities were associated with increased psychological distress. We did not find any paths through hypervigilance regarding COVID-19 and inflammation that explain associations between adverse childhood experiences, social thinning, and psychological distress. These findings emphasize the significant social network changes in the associations between adverse childhood experiences and psychopathology.

Genetic association and drug target exploration of inflammation-related proteins with risk of major depressive disorder

BACKGROUND

In numerous observational studies, circulating inflammation-related proteins have been linked with major depressive disorder (MDD), yet the precise causal direction of this relationship remains unclear. This study aims to investigate the potential causal link between inflammation-related proteins and the risk of developing MDD.

METHODS

We utilized summary data from a genome-wide association study (GWAS) of 91 circulating inflammation-associated proteins in 14,824 individuals of European descent. Additionally, we incorporated findings from a substantial GWAS on MDD, which included 294,322 cases and 741,438 controls. Our analysis employed a two-sample bidirectional Mendelian randomization (MR) approach, with inverse variance weighting (IVW) as the primary method. We augmented this with two supplementary techniques (MR-Egger and weighted median approaches) to detect and address potential pleiotropy. Furthermore, to identify and evaluate possible drug targets, we conducted a thorough search within the Drug-Gene Interaction Database (DGIdb).

RESULTS

Analysis using MR unveiled significant and causative associations between genetically determined CASP-8 (odds ratio (OR): 0.97), CD40 (OR: 0.96), IL-18 (OR: 0.98), SLAMF1 (OR: 0.97), and uPA (OR: 0.98) with MDD. Conversely, reverse MR analysis indicated causal associations between MDD and CCL19 (OR: 1.15), HGF (OR: 1.15), IL-8 (OR: 1.10), IL-18 (OR: 1.11), IL20RA (OR: 1.12), TGFA (OR: 1.12) and TNFSF14 (OR: 1.16). Notably, a significant bidirectional causal link was observed between IL-18 and MDD. Gene-drug analysis identified CD40, HGF, IL-8, IL-18, SLAMF1, and TGFA as potential therapeutic targets.

CONCLUSIONS

We've pinpointed causal links between inflammation-related proteins and MDD, offering compelling and innovative evidence to enhance our understanding of the inflammatory mechanisms involved in MDD and to investigate potential targets for anti-MDD medications.

GluN2A: A Promising Target for Developing Novel Antidepressants

BACKGROUND

Depression is a heterogeneous disorder with high morbidity and disability rates that poses serious problems regarding mental health care. It is now well established that N-methyl D-aspartate receptor (NMDAR) modulators are being increasingly explored as potential therapeutic options for treating depression, although relatively little is known about their mechanisms of action. NMDARs are glutamate-gated ion channels that are ubiquitously expressed in the central nervous system (CNS), and they have been shown to play key roles in excitatory synaptic transmission. GluN2A, the predominant Glu2N subunit of functional NMDARs in neurons, is involved in various physiological processes in the CNS and is associated with diseases such as anxiety, depression, and schizophrenia. However, the role of GluN2A in the pathophysiology of depression has not yet been elucidated.

METHODS

We reviewed several past studies to better understand the function of GluN2A in depression. Additionally, we also summarized the pathogenesis of depression based on the regulation of GluN2A expression, particularly its interaction with neuroinflammation and neurogenesis, which has received considerable critical attention and is highly implicated in the onset of depression.

RESULTS

These evidence suggests that GluN2A overexpression impairs structural and functional synaptic plasticity, which contributes to the development of depression. Consequently, this knowledge is vital for the development of selective antagonists targeting GluN2A subunits using pharmacological and molecular methods.

CONCLUSIONS

Specific inhibition of the GluN2A NMDAR subunit is resistant to chronic stress-induced depressive-like behaviors, making them promising targets for the development of novel antidepressants.

PERK inhibitor (ISRIB) improves depression-like behavior by inhibitions of HPA-axis over-activation in mice exposed to chronic restraint stress

Stressful life event is closely associated with depression, thus strategies that blunt or prevent the negative effect stress on the brain might benefits for the treatment of depression. Although previous study showed the role of protein kinase R (PKR)-like ER kinase (PERK) in inflammation related depression, its involvement in the neuropathology of chronic stress induced depression is still unknown. We tried to explore whether block the PERK pathway would alleviate the animals' depression-like behavior induced by chronic restraint stress (CRS) and investigate the underlying mechanism. The CRS-exposed mice exhibited depression-like behavior, including anhedonia in the sucrose preference test (SPT), and increased immobility time in tail suspension test (TST) and forced swim test (FST). ISRIB administration for 2 weeks significantly improved the depression-like behavior in male mice exposed to CRS, which was manifested by markedly increasing the sucrose preference and reducing the immobility time in the FST and TST. However, we observed that exposure to the same dose of ISRIB in CRS female mice only showed improved anhedonia-like deficits,leaving unaltered improvement in the FST and TST. Mechanically, we found that ISRIB reversed the hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, indicating decreased levels of serum corticosterone, reduced hippocampal glucocorticoidreceptor (GR) expression and expression of FosB in hypothalamic paraventricularnucleus (PVN), which was accompanied by preserved hippocampal neurogenesis. The present findings further expand the potential role of ER stress in depression and provide important details for a therapeutic path forward for PERK inhibitors in mood disorders.

Prophylactic Effects of n-Acethylcysteine on Inflammation-induced Depression-like Behaviors in Mice

Depression, affecting individuals worldwide, is a prevalent mental disease, with an increasing incidence. Numerous studies have been conducted on depression, yet its pathogenesis remains elusive. Recent advancements in research indicate that disturbances in synaptic transmission, synaptic plasticity, and reduced neurotrophic factor expression significantly contribute to depression's pathogenesis. In our study, we utilized adult male C57BL/6J mice. Lipopolysaccharide (LPS) can induce both chronic and acute depression-like symptoms in mice, a widely used model for studying depression associated with inflammation. N-acetylcysteine (NAC) exhibits anti-inflammatory and ameliorative effects on depressive symptoms. This study sought to determine whether NAC use could mitigate inflammatory depressive behavior through the enhancement of synaptic transmission, synaptic plasticity, and increasing levels of brain-derived neurotrophic factor (BDNF). In this study, we discovered that in mice modeled with depression-like symptoms, the expression levels of dendrites, BDNF, and miniature excitatory postsynaptic potential (mEPSC) in glutamatergic neurons, as well as the α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid glutamate receptors (AMPARs) GluA1 and GluA2 subunits, were significantly decreased. These findings suggest an impairment in the synaptic transmission of glutamatergic neurons. Following treatment with NAC, the previously mentioned levels improved, indicating an enhancement in both synaptic transmission and synaptic plasticity. Our results suggest that NAC exerts a protective effect on mouse models of inflammatory depression, potentially through the enhancement of synaptic transmission and plasticity, as well as the restoration of neurotrophic factor expression. These findings offer vital animal experimental evidence supporting NAC's role in mitigating inflammatory depressive behaviors.

Metabolomics in Depression: What We Learn from Preclinical and Clinical Evidences

Depression is one of the predominant common mental illnesses that affects millions of people of all ages worldwide. Random mood changes, loss of interest in routine activities, and prevalent unpleasant senses often characterize this common depreciated mental illness. Subjects with depressive disorders have a likelihood of developing cardiovascular complications, diabesity, and stroke. The exact genesis and pathogenesis of this disease are still questionable. A significant proportion of subjects with clinical depression display inadequate response to antidepressant therapies. Hence, clinicians often face challenges in predicting the treatment response. Emerging reports have indicated the association of depression with metabolic alterations. Metabolomics is one of the promising approaches that can offer fresh perspectives into the diagnosis, treatment, and prognosis of depression at the metabolic level. Despite numerous studies exploring metabolite profiles post-pharmacological interventions, a quantitative understanding of consistently altered metabolites is not yet established. The article gives a brief discussion on different biomarkers in depression and the degree to which biomarkers can improve treatment outcomes. In this review article, we have systemically reviewed the role of metabolomics in depression along with current challenges and future perspectives.

Mining key circadian biomarkers for major depressive disorder by integrating bioinformatics and machine learning

OBJECTIVE

This study aimed to identify key clock genes closely associated with major depressive disorder (MDD) using bioinformatics and machine learning approaches.

METHODS

Gene expression data of 128 MDD patients and 64 healthy controls from blood samples were obtained. Differentially expressed were identified and weighted gene co-expression network analysis (WGCNA) was first performed to screen MDD-related key genes. These genes were then intersected with 1475 known circadian rhythm genes to identify circadian rhythm genes associated with MDD. Finally, multiple machine learning algorithms were applied for further selection, to determine the most critical 4 circadian rhythm biomarkers.

RESULTS

Four key circadian rhythm genes (ABCC2, APP, HK2 and RORA) were identified that could effectively distinguish MDD samples from controls. These genes were significantly enriched in circadian pathways and showed strong correlations with immune cell infiltration. Drug target prediction suggested that small molecules like melatonin and escitalopram may target these circadian rhythm proteins.

CONCLUSION

This study revealed discovered 4 key circadian rhythm genes closely associated with MDD, which may serve as diagnostic biomarkers and therapeutic targets. The findings highlight the important roles of circadian disruptions in the pathogenesis of MDD, providing new insights for precision diagnosis and targeted treatment of MDD.

Sex differences in the combined influence of inflammation and nutrition status on depressive symptoms: insights from NHANES

Background

Both nutrition and inflammation are associated with depression, but previous studies have focused on individual factors. Here, we assessed the association between composite indices of nutrition and inflammation and depression.

Methods

Adult participants selected from the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2018 were chosen. The exposure variable was the Advanced Lung Cancer Inflammation Index (ALI) integrating nutrition and inflammation, categorized into low, medium, and high groups. The outcome variable was depression assessed using the Patient Health Questionnaire-9 (PHQ-9). A multivariable logistic regression model was employed to evaluate the relationship between ALI and the risk of depression.

Results

After extensive adjustment for covariates, in the overall population, participants with moderate and high levels of ALI had a decreased prevalence of depression compared to those with low ALI levels, with reductions of 17% (OR, 0.83; 95% CI: 0.72-0.97) and 23% (OR, 0.77; 95% CI: 0.66-0.91), respectively. Among females, participants with moderate and high ALI levels had a decreased prevalence of depression by 27% (OR, 0.73; 95% CI: 0.60-0.88) and 21% (OR, 0.79; 95% CI: 0.64-0.98), respectively, compared to those with low ALI levels, whereas no significant association was observed among males. Subgroup analyses based on females and males yielded consistent results.

Conclusion

In this study, we observed a negative correlation between moderate to high levels of ALI and the prevalence of depression, along with gender differences. Specifically, in females, greater attention should be given to the nutritional and inflammatory status.

Identifying depression's genetic role as a precursor to sepsis and increased mortality risk: Comprehensive insights from mendelian randomization analysis

BACKGROUND

Previous retrospective studies have shown a correlation between depression and increased risk of infections, including a moderate rise in sepsis likelihood associated with severe depression and anxiety. To investigate the potential causal links between depression, sepsis, and mortality risks, while considering confounding factors, we employed a Mendelian randomization (MR) approach.

METHODS

In this two-sample Mendelian randomization study, we analyzed data from a large-scale genome-wide association study on depression, involving 807,553 European individuals (246,363 cases, 561,190 controls). We extracted SNP associations with sepsis and 28-day mortality from UK Biobank GWAS outcomes. The correlation analysis primarily employed the inverse-variance weighted method, supplemented by sensitivity analyses for heterogeneity and pleiotropy assessment.

RESULTS

Our analysis revealed a potential causal link between depression and an increased risk of sepsis (OR = 1.246, 95% CI: 1.076-1.442, P = 0.003), but no causal association was found with sepsis-induced mortality risk (OR = 1.274, 95% CI: 0.891-1.823, P = 0.184). Sensitivity analyses confirmed the robustness of these findings.

CONCLUSIONS

We identified a potential causal association between depression and heightened sepsis risk, while no link was found with sepsis-induced mortality. These findings suggest that effective management of depression could be important in preventing sepsis.

Exploring pathogenesis and biomarkers through establishment of a rat model of male infertility with liver depression and kidney deficiency

OBJECTIVES

To establish a rat model that accurately replicates the clinical characteristics of male infertility (MI) with Liver Depression and Kidney Deficiency (LD & KD) and investigate the pathogenesis.

METHODS

After subjecting the rats to chronic restraint stress (CRS) and adenine treatment, a series of tests were conducted, including ethological assessments, evaluations of reproductive characteristics, measurements of biochemical parameters, histopathological examinations, and analyses of urinary metabolites. Additionally, bioinformatics predictions were performed for comprehensive analysis.

RESULTS

Compared to the control, the model exhibited significant manifestations of MI with LD & KD, including reduced responsiveness, diminished frequency of capturing estrous female rats, and absence of mounting behavior. Additionally, the kidney coefficient increased markedly, while the coefficients of the testis and epididymis decreased significantly. Sperm counts and viabilities decreased notably, accompanied by an increase in sperm abnormalities. Dysregulation of reproductive hormone levels in the serum was observed, accompanied by an upregulation of proinflammatory cytokines expressions in the liver and kidney, as well as exacerbated oxidative stress in the penile corpus cavernosum and testis. The seminiferous tubules in the testis exhibited a loose arrangement, loss of germ cells, and infiltration of inflammatory cells. Furthermore, utilizing urinary metabolomics and bioinformatics analysis, 5 key biomarkers and 2 crucial targets most closely linked to MI were revealed.

CONCLUSION

The study successfully established a clinically relevant animal model of MI with LD & KD. It elucidates the pathogenesis of the condition, identifies key biomarkers and targets, and provides a robust scientific foundation for the prediction, diagnosis, and treatment of MI with LD & KD.

Ghrelin/GHSR signaling in the lateral septum ameliorates chronic stress-induced depressive-like behaviors

Ghrelin is a gastrointestinal hormone on feeding and metabolism regulation, and acts through its receptor-growth hormone secretagogue receptor (GHSR), which is widely distributed throughout the central nervous system. Recent studies have suggested that ghrelin plays an important role in the regulation of depression, but the underlying mechanisms remain uncertain. Lateral septum (LS) is a critical brain region in modulating depression. Therefore, we investigated the role of ghrelin/GHSR signaling in the LS on the depressive-like behaviors of mice under conditions of chronic stress by using behavioral tests, neuropharmacology, and molecular biology techniques. We found that infusion of ghrelin into the LS produced antidepressant-like responses in mice. Activation of LS GABAergic neurons was involved in the antidepressant effect of ghrelin. Importantly, GHSR was highly expressed and distributed in the LS neurons. Blockade of GHSR in the LS reversed the ghrelin-induced antidepressant-like effects. Molecular knockdown of GHSR in the LS induced depressive-like symptoms in mice. Furthermore, administration of ghrelin into the LS alleviated depressive-like behaviors induced by chronic social defeat stress (CSDS). Consistent with the neuropharmacological results, overexpression of GHSR in the LS reversed CSDS-induced depressive-like behaviors. Our findings clarify a key role for ghrelin/GHSR signaling in the regulation of chronic stress-induced depressive-like behaviors, which could provide new strategies for the treatment of depression.

Association and biological pathways between lung function and incident depression: a prospective cohort study of 280,032 participants

BACKGROUND

Lung health is increasingly recognized as an essential factor in mental health. However, prospective evidence on lung function with incident depression remains to be determined. The study aimed to examine the prospective association between impaired lung function and incident depression and the underlying biological mechanisms.

METHODS

This prospective cohort study comprised 280,032 non-depressed individuals with valid lung function measurements from the UK Biobank. Lung function was assessed through the forced vital capacity (FVC) or forced expiratory volume in 1 s (FEV1). Cox proportional hazard models were applied to estimate the associations between lung function and incident depression. Mediation analyses were fitted to investigate the potential mediating role of biomarkers and metabolites in the association.

RESULTS

A total of 9514 participants (3.4%) developed depression during a median follow-up of 13.91 years. Individuals in the highest quartile had a lower risk of depression (FVC % predicted: HR = 0.880, 95% CI = 0.830-0.933; FEV1% predicted: HR = 0.854, 95% CI = 0.805-0.905) compared with those in the lowest quartile of the lung function indices. Additionally, the restricted cubic splines suggested lung function indices had reversed J-shaped associations with incident depression (nonlinear P < 0.05 for FVC % predicted and FEV1% predicted). Impaired lung function yielded similar risk estimates (HR = 1.124, 95% CI = 1.074-1.176). Biomarkers involving systemic inflammation, erythrocytes, and liver and renal function may be potential mediators in the lung function-depression association.

CONCLUSIONS

This study revealed that the higher risk of developing depression was associated with impaired lung function. Also, the association might be partially mediated by biomarkers including systemic inflammation, erythrocytes, and liver and renal function, though these mediation findings should be interpreted with caution due to potential temporal ambiguity.

Identification of Key Genes and Imbalanced SNAREs Assembly in the Comorbidity of Polycystic Ovary Syndrome and Depression

BACKGROUND

Women with polycystic ovary syndrome (PCOS) have increased odds of concurrent depression, indicating that the relationship between PCOS and depression is more likely to be comorbid. However, the underlying mechanism remains unclear. Here, we aimed to use bioinformatic analysis to screen for the genetic elements shared between PCOS and depression.

METHODS

Differentially expressed genes (DEGs) were screened out through GEO2R using the PCOS and depression datasets in NCBI. Protein-protein interaction (PPI) network analysis and enrichment analysis were performed to identify the potential hub genes. After verification using other PCOS and depression datasets, the associations between key gene polymorphism and comorbidity were further studied using data from the UK biobank (UKB) database.

RESULTS

In this study, three key genes, namely, SNAP23, VTI1A, and PRKAR1A, and their related SNARE interactions in the vesicular transport pathway were identified in the comorbidity of PCOS and depression. The rs112568544 at SNAP23, rs11077579 and rs4458066 at PRKAR1A, and rs10885349 at VTI1A might be the genetic basis of this comorbidity.

CONCLUSIONS

Our study suggests that the SNAP23, PRKAR1A, and VTI1A genes can directly or indirectly participate in the imbalanced assembly of SNAREs in the pathogenesis of the comorbidity of PCOS and depression. These findings may provide new strategies in diagnosis and therapy for this comorbidity.

Serum proteomic biomarker investigation of vascular depression using data-independent acquisition: a pilot study

Background

Vascular depression (VaD) is a depressive disorder closely associated with cerebrovascular disease and vascular risk factors. It remains underestimated owing to challenging diagnostics and limited information regarding the pathophysiological mechanisms of VaD. The purpose of this study was to analyze the proteomic signatures and identify the potential biomarkers with diagnostic significance in VaD.

Methods

Deep profiling of the serum proteome of 35 patients with VaD and 36 controls was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Functional enrichment analysis of the quantified proteins was based on Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and Reactome databases. Machine learning algorithms were used to screen candidate proteins and develop a protein-based model to effectively distinguish patients with VaD.

Results

There were 29 up-regulated and 31 down-regulated proteins in the VaD group compared to the controls (|log2FC| ≥ 0.26, p ≤ 0.05). Enrichment pathways analyses showed that neurobiological processes related to synaptic vesicle cycle and axon guidance may be dysregulated in VaD. Extrinsic component of synaptic vesicle membrane was the most enriched term in the cellular components (CC) terms. 19 candidate proteins were filtered for further modeling. A nomogram was developed with the combination of HECT domain E3 ubiquitin protein ligase 3 (HECTD3), Nidogen-2 (NID2), FTO alpha-ketoglutarate-dependent dioxygenase (FTO), Golgi membrane protein 1 (GOLM1), and N-acetylneuraminate lyase (NPL), which could be used to predict VaD risk with favorable efficacy.

Conclusion

This study offers a comprehensive and integrated view of serum proteomics and contributes to a valuable proteomics-based diagnostic model for VaD.

Progress of plant polyphenol extracts in treating depression by anti-neuroinflammatory mechanism: A review

There is a growing body of evidence supporting the involvement of central nervous system inflammation in the pathophysiology of depression. Polyphenols are a diverse group of compounds known for their antioxidative and anti-inflammatory properties. They offer a promising and effective supplementary approach to alleviating neuropsychiatric symptoms associated with inflammation-induced depression. This paper provides a summary of the potential anti-neuroinflammatory mechanisms of plant polyphenol extracts against depression. This includes direct interference with inflammatory regulators and inhibition of the expression of pro-inflammatory cytokines. Additionally, it covers downregulating the expression of pro-inflammatory cytokines by altering protein kinases or affecting the activity of the signaling pathways that they activate. These pathways interfere with the conduction of signaling molecules, resulting in the destruction and reduced synthesis of all inflammatory mediators and cytokines. This reduces the apoptosis of neurons and plays a neuroprotective role. This paper provides a theoretical basis for the clinical application of plant polyphenols.

Relationships between depression level and serum inflammatory factors and thyroxine levels in patients with malignant bone tumors associated with depression

OBJECTIVE

To elucidate the relationships between depression level and serum inflammatory factors and thyroxine levels in patients with malignant bone tumors associated with depression.

METHODS

The depression (n = 28) and non-depression groups (n = 35) were established. Another 35 healthy subjects were selected as the control group. The severity of depression was assessed, and the depression group received the selective serotonin reuptake inhibitor antidepressant sertraline for 4 weeks. Serum levels of inflammatory factors and thyroxine, and the correlation between inflammatory factors, thyroxine, and HAMD-17 score were analyzed.

RESULTS

The IL-1β, IL-6, and IL-21 levels were lower and TGF-β1, IL-10, and IL-27 were higher in the depression group after treatment than before treatment. After treatment, T3 levels were higher and T4 levels were lower in the depression group. T4 levels were higher in patients with major depression than those with mild depression. IL-1β and IL-21 levels were elevated in moderately depressed patients [(11.13 ± 1.49) ng/L、(9.71 ± 1.26) ng/L], and IL-1β levels were elevated in severely depressed patients [(11.26 ± 1.95) ng/L], compared to mildly depressed patients [(9.36 ± 1.25) ng/L, (7.95 ± 1.31) ng/L] (all p < 0.05). Serum IL-1β, IL-6, and IL-21 were positively correlated with the total HAMD-17 score, and TGF-β1 and IL-10 were negatively correlated with the total HAMD-17 score.

CONCLUSION

Depression degree in patients with malignant bone tumors correlates with serum inflammatory factors and thyroxine levels. Measurement of serum inflammatory factors and thyroxine levels can assess the progression and prognosis of depressed patients.

Plasma metabolomics reveals the intervention mechanism of different types of exercise on chronic unpredictable mild stress-induced depression rat model

OBJECTIVE

To study the effects of different types of exercise on the plasma metabolomics of chronic unpredictable mild stress (CUMS)-induced depressed rats based on 1H-NMR metabolomics techniques, and to explore the potential mechanisms of exercise for the treatment of depression. Rats were randomly divided into blank control group (C), CUMS control group (D), pre-exercise with CUMS group (P), CUMS with aerobic exercise group, CUMS with resistance exercise group (R), and CUMS with aerobic + resistance exercise group (E). The corresponding protocol intervention was applied to each group of rats. Body weight, sucrose preference and open field tests were performed weekly during the experiment to evaluate the extent of depression in rats. Plasma samples from each group of rats were collected at the end of the experiment, and then the plasma was analyzed by 1H-NMR metabolomics combined with multivariate statistical analysis methods to identify differential metabolites and perform metabolic pathway analysis. (1) Compared with the group D, the body weight, sucrose preference rate, and the number of crossings and standings in the different types of exercise groups were significantly improved (p < 0.05 or p < 0.01). (2) Compared to group C, a total of 15 differential metabolites associated with depression were screened in the plasma of rats in group D, involving 6 metabolic pathways. Group P can regulate the levels of 6 metabolites: valine, lactate, inositol, glucose, phosphocreatine, acetoacetic acid. Group A can regulate the levels of 6 metabolites: N-acetylglycoprotein, leucine, lactate, low density lipoprotein, glucose and acetoacetic acid. Group R can regulate the levels of 6 metabolites: choline, lactate, inositol, glucose, phosphocreatine and acetoacetic acid. Group E can regulate the levels of 5 metabolites: choline, citric acid, glucose, acetone and acetoacetic acid. The different types of exercise groups can improve the depressive symptoms in CUMS rats, and there are common metabolites and metabolic pathways for their mechanism of effects. This study provides a powerful analytical tool to study the mechanism of the antidepressant effect of exercise, and provides an important method and basis for the early diagnosis, prevention and treatment of depression.

Narrative Review: Pathogenesis of the Inflammatory Response and Intestinal Flora in Depression

Depression, as a common mental illness that is often accompanied by suicidal and homicidal behaviors, is one of the most important diseases in the medical field that requires urgent attention. The pathogenesis of depression is complex, and the current therapeutic drugs such as tricyclic antidepressants (TCAs), monoamine oxidase inhibitors, and secondary serotonin reuptake inhibitors have certain shortcomings. The inflammatory factor hypothesis, one of the pathogenesis of depression, suggests that inflammatory response is a key factor leading to the occurrence and development of depression, and that overactivation of inflammatory factors such as NLRP3, Toll-like receptor 4, and IDO leads to immune-system dysfunction and depression. The other pathogenic hypothesis, the gut flora hypothesis, has also been the focus of recent research. The gut flora may work together with inflammatory factors to cause depression. The approach to treating depression has been by altering the gut flora through drugs or probiotics. However, effective and clear treatment methods are lacking. In this study, by exploring the involvement of intestinal flora and inflammatory factors in the pathogenesis of depression, we found that improving the intestinal flora can affect inflammatory factors and, therefore, provide research ideas for the development of novel drugs to treat depression.

Protein Plasma Levels of the IGF Signalling System Are Altered in Major Depressive Disorder

The Insulin-like growth factor 2 (IGF-2) has been recently proven to alleviate depressive-like behaviors in both rats and mice models. However, its potential role as a peripheral biomarker has not been evaluated in depression. To do this, we measured plasma IGF-2 and other members of the IGF family such as Binding Proteins (IGFBP-1, IGFBP-3, IGFBP-5 and IGFBP-7) in a depressed group of patients (n = 51) and in a healthy control group (n = 48). In some of these patients (n = 15), we measured these proteins after a period (19 ± 6 days) of treatment with antidepressants. The Hamilton Depressive Rating Scale (HDRS) and the Self-Assessment Anhedonia Scale (SAAS) were used to measure depression severity and anhedonia, respectively. The general cognition state was assessed by the Mini-Mental State Examination (MMSE) test and memory with the Free and Cued Selective Reminding Test (FCSRT). The levels of both IGF-2 and IGFBP-7 were found to be significantly increased in the depressed group; however, only IGF-2 remained significantly elevated after correction by age and sex. On the other hand, the levels of IGF-2, IGFBP-3 and IGFBP-5 were significantly decreased after treatment, whereas only IGFBP-7 was significantly increased. Therefore, peripheral changes in the IGF family and their response to antidepressants might represent alterations at the brain level in depression.

Antidepressant-like Effects of Representative Types of Food and Their Possible Mechanisms

Depression is a mental disorder characterized by low mood, lack of motivation, negative cognitive outlook, and sleep problems. Suicide may occur in severe cases, although suicidal thoughts are not seen in all cases. Globally, an estimated 350 million individuals grapple with depression, as reported by the World Health Organization. At present, drug and psychological treatments are the main treatments, but they produce insufficient responses in many patients and fail to work at all in many others. Consequently, treating depression has long been an important topic in society. Given the escalating prevalence of depression, a comprehensive strategy for managing its symptoms and impacts has garnered significant attention. In this context, nutritional psychiatry emerges as a promising avenue. Extensive research has underscored the potential benefits of a well-rounded diet rich in fruits, vegetables, fish, and meat in alleviating depressive symptoms. However, the intricate mechanisms linking dietary interventions to brain function alterations remain largely unexplored. This review delves into the intricate relationship between dietary patterns and depression, while exploring the plausible mechanisms underlying the impact of dietary interventions on depression management. As we endeavor to unveil the pathways through which nutrition influences mental well-being, a holistic perspective that encompasses multidisciplinary strategies gains prominence, potentially reshaping how we approach and address depression.

Brain-Derived Neurotrophic Factor (BDNF) as a Predictor of Treatment Response in Major Depressive Disorder (MDD): A Systematic Review

Brain-derived neurotrophic factor (BDNF) has been studied as a biomarker of major depressive disorder (MDD). Besides diagnostic biomarkers, clinically useful biomarkers can inform response to treatment. We aimed to review all studies that sought to relate BDNF baseline levels, or BDNF polymorphisms, with response to treatment in MDD. In order to achieve this, we performed a systematic review of studies that explored the relation of BDNF with both pharmacological and non-pharmacological treatment. Finally, we reviewed the evidence that relates peripheral levels of BDNF and BDNF polymorphisms with the development and management of treatment-resistant depression.

Physical Exercise as Disease-Modifying Alternative against Alzheimer's Disease: A Gut-Muscle-Brain Partnership

Alzheimer's disease (AD) is a common cause of dementia characterized by neurodegenerative dysregulations, cognitive impairments, and neuropsychiatric symptoms. Physical exercise (PE) has emerged as a powerful tool for reducing chronic inflammation, improving overall health, and preventing cognitive decline. The connection between the immune system, gut microbiota (GM), and neuroinflammation highlights the role of the gut-brain axis in maintaining brain health and preventing neurodegenerative diseases. Neglected so far, PE has beneficial effects on microbial composition and diversity, thus providing the potential to alleviate neurological symptoms. There is bidirectional communication between the gut and muscle, with GM diversity modulation and short-chain fatty acid (SCFA) production affecting muscle metabolism and preservation, and muscle activity/exercise in turn inducing significant changes in GM composition, functionality, diversity, and SCFA production. This gut-muscle and muscle-gut interplay can then modulate cognition. For instance, irisin, an exercise-induced myokine, promotes neuroplasticity and cognitive function through BDNF signaling. Irisin and muscle-generated BDNF may mediate the positive effects of physical activity against some aspects of AD pathophysiology through the interaction of exercise with the gut microbial ecosystem, neural plasticity, anti-inflammatory signaling pathways, and neurogenesis. Understanding gut-muscle-brain interconnections hold promise for developing strategies to promote brain health, fight age-associated cognitive decline, and improve muscle health and longevity.

Deiodinase Types 1 and 3 and Proinflammatory Cytokine Values May Discriminate Depressive Disorder Patients from Healthy Controls

INTRODUCTION

Depressive disorders are multifactorial diseases in that a variety of factors may play a role in their etiology, including inflammation and abnormalities in the thyroid hormone (TH) metabolism and levels. The purpose of this study was to evaluate iodothyronine deiodinases (DIOs) and DIO-interacting cytokines as possible biomarkers in the diagnosis of depressive disorders.

METHODS

This study enrolled 73 patients diagnosed with recurrent depressive disorder (rDD) and 54 controls. The expressions of DIO1, DIO2, DIO3, IL1B, IL6, TNFA, and IFNG genes, encoding three types of DIOs (1, 2, and 3), interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, were assessed using the polymerase chain reaction in blood cells and an enzymatic immunoassay method in serum. The levels of examined molecules between patients and controls were compared, and correlations and diagnostic values were evaluated.

RESULTS

Lower levels of DIO2 and higher levels of IL1B, IL6, and TNFA were found in patients compared to controls. The protein concentrations of DIO1 and DIO2 were lower, while that of DIO3 was higher, in patients than in controls. Serum IL-1β, IL-6, and TNF-α were also higher in patients than in controls. The area under the curve (AUC) of the IL-1β, IL-6, DIO1, and DIO3 proteins was >0.7 for discriminating patients with rDD from controls.

CONCLUSIONS

The expressions of genes for DIO2, IL-1β, IL-6, and TNF-α may have a role in the estimation of processes present in depressive disorders. We can cautiously claim that DIO1 and DIO3 and pivotal cytokines, mainly IL-1β and IL-6, may play a role in depression diagnosis, and further studies are suggested to explain the exact role of these molecules in larger samples with more precise methods.

Diagnostic value of serum neuroactive substances in the acute exacerbation of chronic obstructive pulmonary disease complicated with depression

We aimed to investigate the potential diagnostic value of five serum neuroactive substances in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) complicated with depression. A total of 103 patients with AECOPD were enrolled between August 2020 and August 2021. All patients were assessed using a self-rating depression scale and divided into AECOPD with or without depression groups. Baseline data and serum neuroactive substance levels were compared between the two groups. Logistic regression was used to identify the risk factors. The diagnostic performance of neuroactive substances was evaluated using receiver operating characteristic (ROC) curves. Patients with AECOPD complicated with depression exhibited higher partial pressure of CO2 values and higher chronic obstructive pulmonary disease assessment test (CAT) scores. An elevated proportion of patients with more than two acute exacerbations (AEs) in the previous year was observed in this patient group (all P < 0.001). The CAT score and number of AEs during the previous year were identified as independent risk factors for AECOPD complicated with depression. No significant differences were observed in the levels of aspartic acid and glutamate between the two groups (P > 0.05). Serum γ-aminobutyric acid (GABA) and glycine (Gly) levels were decreased. In contrast, serum nitric oxide (NO) levels were increased in the AECOPD complicated with the depression group (P < 0.05). Serum GABA and Gly levels exhibited a negative correlation, and NO levels positively correlated with the number of AEs in the previous year and the CAT score. The area under the ROC curve values for GABA, Gly, and NO were 0.755, 0.695, and 0.724, respectively. Serum GABA exhibited a sensitivity of 85.1% and a specificity of 58.9%, below the cut-off value of 4855.98 nmol/L. Serum GABA, Gly, and NO may represent potential biomarkers for AECOPD complicated with depression.

Improving mental health care in depression: A call for action

Depressive disorders have one of the highest disability-adjusted life years (DALYs) of all medical conditions, which led the European Psychiatric Association to propose a policy paper, pinpointing their unmet health care and research needs. The first part focuses on what can be currently done to improve the care of patients with depression, and then discuss future trends for research and healthcare. Through the narration of clinical cases, the different points are illustrated. The necessary political framework is formulated, to implement such changes to fundamentally improve psychiatric care. The group of European Psychiatrist Association (EPA) experts insist on the need for (1) increased awareness of mental illness in primary care settings, (2) the development of novel (biological) markers, (3) the rapid implementation of machine learning (supporting diagnostics, prognostics, and therapeutics), (4) the generalized use of electronic devices and apps into everyday treatment, (5) the development of the new generation of treatment options, such as plasticity-promoting agents, and (6) the importance of comprehensive recovery approach. At a political level, the group also proposed four priorities, the need to (1) increase the use of open science, (2) implement reasonable data protection laws, (3) establish ethical electronic health records, and (4) enable better healthcare research and saving resources.

Illuminating the way: the role of bright light therapy in the treatment of depression

INTRODUCTION

Despite the growing number of different therapeutic options, treatment of depression is still a challenge. A broader perspective reveals the benefits of bright light therapy (BLT). It stimulates intrinsically photosensitive retinal ganglion cells, which induces a complex cascade of events, including alterations in melatonergic, neurotrophic, GABAergic, glutamatergic, noradrenergic, serotonergic systems, and HPA axis, suggesting that BLT effects expand beyond the circadian pacemaker.

AREAS COVERED

In this review, the authors present and discuss recent data of BLT in major depressive disorder, non-seasonal depression, bipolar depression or depressive phase of bipolar disorder, and seasonal affective disorder, as well as in treatment-resistant depression (TRD). The authors further highlight BLT effects in various depressive disorders compared to placebo and report data from several studies suggesting a response to BLT in TRD. Also, the authors report data showing that BLT can be used both as a monotherapy or in combination with other pharmacological treatments.

EXPERT OPINION

BLT is an easy-to-use and low-budget therapy with good tolerability. Future studies should focus on clinical and biological predictors of response to BLT, on defining specific populations which may benefit from BLT and establishing treatment protocols regarding timing, frequency, and duration of BLT.

Dietary Nutrient Deficiencies and Risk of Depression (Review Article 2018-2023)

Depression is classified as one of the most common mental disorders. Its prevalence has recently increased, becoming a growing public health threat. This review focuses on clarifying the role and importance of individual nutrients in the diet and the impact of nutrient deficiencies on the risk of depression. Deficiencies in nutrients such as protein, B vitamins, vitamin D, magnesium, zinc, selenium, iron, calcium, and omega-3 fatty acids have a significant impact on brain and nervous system function, which can affect the appearance of depressive symptoms. However, it is important to remember that diet in itself is not the only factor influencing the risk of or helping to treat depression. There are many other aspects, such as physical activity, sleep, stress management, and social support, that also play an important role in maintaining mental health. The data review observed that most of the available analyses are based on cross-sectional studies. Further studies, including prospective cohort, case-control studies, are recommended to draw more reliable conclusions.

Frequency-resolved connectome alterations in major depressive disorder: A multisite resting fMRI study

BACKGROUND

Functional connectome studies have revealed widespread connectivity alterations in major depressive disorder (MDD). However, the low frequency bandpass filtering (0.01-0.08 Hz or 0.01-0.1 Hz) in most studies have impeded our understanding on whether and how these alterations are affected by frequency of interest.

METHODS

Here, we performed frequency-resolved (0.01-0.06 Hz, 0.06-0.16 Hz and 0.16-0.24 Hz) connectome analyses using a large-sample resting-state functional MRI dataset of 1002 MDD patients and 924 healthy controls from seven independent centers.

RESULTS

We reported significant frequency-dependent connectome alterations in MDD in left inferior parietal, inferior temporal, precentral, and fusiform cortices and bilateral precuneus. These frequency-dependent connectome alterations are mainly derived by abnormalities of medium- and long-distance connections and are brain network-dependent. Moreover, the connectome alteration of left precuneus in high frequency band (0.16-0.24 Hz) is significantly associated with illness duration.

LIMITATIONS

Multisite harmonization model only removed linear site effects. Neurobiological underpinning of alterations in higher frequency (0.16-0.24 Hz) should be further examined by combining fMRI data with respiration, heartbeat and blood flow recordings in future studies.

CONCLUSIONS

These results highlight the frequency-dependency of connectome alterations in MDD and the benefit of examining connectome alteration in MDD under a wider frequency band.

The association of brain-derived neurotrophic factor with the diagnosis and treatment response in depression

INTRODUCTION

Recent evidence from the studies evaluating the association between brain derived neurotrophic factor (BDNF) concentration/levels, BDNF Val66Met (rs6265) polymorphism and major depressive disorders, referred as depression, and the association between BDNF levels and/or BDNF Val66Met with the treatment response in depression, is presented.

AREAS COVERED

This mini review focuses on the changes in the peripheral BDNF levels in blood (serum, plasma, platelets) in patients with depression before or after treatment with antidepressant drugs or different therapeutic strategies. In addition, this review describes the recent data on the possible association between different antidepressants/therapeutic strategies and the particular BDNF Val66Met genotypes, evaluating the risk alleles associated with the response in patients with depression.

EXPERT OPINION

BDNF has an important role in the pathophysiology and treatment response in depression. Most data reveal that peripheral BDNF levels are lower before than after antidepressant treatment and might be used as potential biomarkers of therapeutic response. Novel therapeutic strategies should target restoring/increasing BDNF levels.

α7 Nicotinic acetylcholine receptor: a key receptor in the cholinergic anti-inflammatory pathway exerting an antidepressant effect

Depression is a common mental illness, which is related to monoamine neurotransmitters and the dysfunction of the cholinergic, immune, glutamatergic, and neuroendocrine systems. The hypothesis of monoamine neurotransmitters is one of the commonly recognized pathogenic mechanisms of depression; however, the drugs designed based on this hypothesis have not achieved good clinical results. A recent study demonstrated that depression and inflammation were strongly correlated, and the activation of alpha7 nicotinic acetylcholine receptor (α7 nAChR)-mediated cholinergic anti-inflammatory pathway (CAP) in the cholinergic system exhibited good therapeutic effects against depression. Therefore, anti-inflammation might be a potential direction for the treatment of depression. Moreover, it is also necessary to further reveal the key role of inflammation and α7 nAChR in the pathogenesis of depression. This review focused on the correlations between inflammation and depression as well-discussed the crucial role of α7 nAChR in the CAP.

Gut microbiota-SCFAs-brain axis associated with the antidepressant activity of berberine in CUMS rats

BACKGROUND

The anti-depressant effect of berberine (BBR) has been widely reported. However, the underlying mechanism remains unclear. The microbiota-gut-brain (MGB) axis plays a key role in the pathogenesis of depression. Therefore, we aimed to explore the anti-depressant mechanisms of BBR involving the association of the gut microbiota, neurotransmitters, BDNF, and SCFAs in chronic unpredictable mild stress (CUMS)-induced depressive rats.

METHODS

The antidepressant effects of BBR were detected by open-field test, 1 % sucrose preference test and body weight test in CUMS-induced depressive rats. 16S rDNA sequencing was performed to identify the change of gut microbiota. The concentrations of fecal SCFAs were analyzed by GC-MS targeted metabolomics. At the same time, neurotransmitters and BDNF expression were measured by enzyme linked immunosorbent assay (ELISA).

RESULTS

BBR improved depression-like behaviors in CUMS rats by increasing the expression of serotonin (5-HT), norepinephrine (NE), dopamine (DA), and BDNF in the hippocampus. BBR regulates Firmicutes, Bacteroidetes, and Lachnospiraceae in depressive rats, resulting in the alteration of the synthesis and metabolism of SCFAs, including acetic, propanoic, and isovaleric acids.

LIMITATIONS

Direct evidence that BBR improves depressive behaviors via gut microbiota-SCFAs-brain axis is lacking, and only male rats were investigated in the present study.

CONCLUSION

The anti-depressant mechanism of BBR is related to the regulation of the MGB axis via modulating the gut microbiota-SCFAs-monoamine neurotransmitters/BDNF.

Neuromicrobiology, an emerging neurometabolic facet of the gut microbiome?

The concept of the gut microbiome is emerging as a metabolic interactome influenced by diet, xenobiotics, genetics, and other environmental factors that affect the host's absorption of nutrients, metabolism, and immune system. Beyond nutrient digestion and production, the gut microbiome also functions as personalized polypharmacy, where bioactive metabolites that our microbes excrete or conjugate may reach systemic circulation and impact all organs, including the brain. Appreciable evidence shows that gut microbiota produce diverse neuroactive metabolites, particularly neurotransmitters (and their precursors), stimulating the local nervous system (i.e., enteric and vagus nerves) and affecting brain function and cognition. Several studies have demonstrated correlations between the gut microbiome and the central nervous system sparking an exciting new research field, neuromicrobiology. Microbiome-targeted interventions are seen as promising adjunctive treatments (pre-, pro-, post-, and synbiotics), but the mechanisms underlying host-microbiome interactions have yet to be established, thus preventing informed evidence-based therapeutic applications. In this paper, we review the current state of knowledge for each of the major classes of microbial neuroactive metabolites, emphasizing their biological effects on the microbiome, gut environment, and brain. Also, we discuss the biosynthesis, absorption, and transport of gut microbiota-derived neuroactive metabolites to the brain and their implication in mental disorders.

Suicide and Neurotrophin Factors: A Systematic Review of the Correlation between BDNF and GDNF and Self-Killing

According to WHO data, suicide is a public health priority. In particular, suicide is the fourth-leading cause of death in young people. Many risk factors of suicide are described, including individual-, relationship-, community-, and societal-linked ones. The leading factor is the diagnosis of mental illness. Nevertheless, not all people who attempt suicide are psychiatric patients; these characteristics help define high-risk populations. There are currently no useful biomarkers to indicate the risk of suicide. In recent years, neurotrophic factors have increasingly become of scientific interest. This review aims to summarize the current scientific knowledge on the correlation between BDNF and GDNF and suicide, to theorize whether neurotrophins could be a reliable marker for an early diagnosis of suicidal risk. The authors conducted a systematic review following PRISMA criteria. They found eight research papers in agreement with the inclusion criteria. According to the results of these studies, there may be a connection between BDNF brain levels and complete suicide, although there are discrepancies. A lack of interest in GDNF may suggest less involvement in the suicidal dynamic. Further studies may provide helpful information to researchers.

Mechanism of lily bulb and Rehmannia decoction in the treatment of lipopolysaccharide-induced depression-like rats based on metabolomics study and network pharmacology

CONTEXT

Lily bulb and Rehmannia decoction (LBRD), consisting of Lilium henryi Baker (Liliaceae) and Rehmannia glutinosa (Gaertn) DC (Plantaginaceae), is a specialized traditional Chinese medicine formula for treating depression. However, the underlying mechanisms, especially the relationship between LBRD efficacy and metabolomics, remains unclear.

OBJECTIVE

This study was aimed to investigate the metabolic mechanism of LBRD in treating depression.

MATERIALS AND METHODS

Network pharmacology was conducted using SwissTargetPrediction, DisGeNET, DrugBank, Metascape, etc., to construct component-target-pathway networks. The depression-like model was induced by intraperitoneal injection with lipopolysaccharide (LPS) (0.3 mg/kg) for 14 consecutive days. After the administration of LBRD (90 g/kg) and fluoxetine (2 mg/kg) for 14 days, we assessed behaviour and the levels of neurotransmitter, inflammatory cytokine and circulating stress hormone. Prefrontal metabolites of rats were detected by using liquid chromatography-mass spectrometry metabolomics method.

RESULTS

The results of network pharmacology showed that LBRD mainly acted on neurotransmitter and second messenger pathways. Compared to the model group, LBRD significantly ameliorated depressive phenotypes and increased the level of 5-HT (13.4%) and GABA (24.8%), as well as decreased IL-1β (30.7%), IL-6 (32.8%) and TNF-α (26.6%). Followed by LBRD treatment, the main metabolites in prefrontal tissue were contributed to retrograde endocannabinoid signalling, glycerophospholipid metabolism, glycosylphosphatidylinositol-anchor biosynthesis, autophagy signal pathway, etc.

DISCUSSION AND CONCLUSIONS

LBRD were effective at increasing neurotransmitter, attenuating proinflammatory cytokine and regulating glycerophospholipid metabolism and glutamatergic synapse, thereby ameliorating depressive phenotypes. This research will offer reference for elucidating the metabolomic mechanism underlying novel antidepressant agents contained LBRD formula.

Evaluation of rosmarinic acid against myocardial infarction in maternally separated rats

Depression and coronary heart diseases are the common comorbid disorder affecting humans globally. The present study evaluated the effectiveness of rosmarinic acid (RA) against myocardial infarction (MI) in comorbid depression induced by maternal separation in rats. Maternal stress is one of the childhood crises that may be a potential risk factor for coronary heart disease in later part of life. As per protocol, 70-80% of pups were separated daily for 3 h between postnatal day 1 (PND1) and postnatal day 21 (PND21). Forced-swim test, sucrose preference test, and electrocardiography were performed during the experiment. Body weight was measured on PND0, PND35, and PND55. Orally rosmarinic acid (25 mg/kg and 50 mg/kg) and fluoxetine (10 mg/kg) was done from PND35 to PND55. On PND53 and PND54, isoproterenol (100 mg/kg, subcutaneously) was administered to induce myocardial infarction. On PND55, blood was collected and animals sacrificed, and plasma corticosterone, brain-derived neurotrophic factor, cardiac biomarkers, interleukine-10, and anti-oxidant parameters were measured. Rosmarinic acid and fluoxetine ameliorated the maternal separation-induced increase in immobility period, anhedonia, body weight, ST elevation, corticosterone, creatine kinase-MB (CK-MB), and lactate dehydrogenase (LDH). At the same time, both drugs elevated the tissue levels of BDNF, IL-10, glutathione, and superoxide dismutase activity. This study provides the first experimental evidence that maternal stress is an independent risk factor of cardiac abnormalities in rats. Moreover, maternal stress synergistically increases the severity of cardiac abnormalities induced by isoproterenol. Interestingly, fluoxetine and rosmarinic acid effectively ameliorated behavioral anomalies and myocardial infarction in maternally separated rats. Schematic representation of possible molecular mechanism of action of rosmarinic acid against MS-induced myocardial infarction. RA, rosmarinic acid; MS, maternal separation; PND, postnatal days; ISO, isoproterenol; BDNF, brain-derived neurotrophic factor; GSH, glutathione; SOD, superoxide dismutase; IL-10, interleukin-10; MI, myocardial infarction.

The potential risk factors of early-onset post-stroke depression from immuno-inflammatory perspective

Background

Mounting evidence strongly uncovered that peripheral immuno-inflammatory response induced by acute stroke is associated with the appearance of post-stroke depression (PSD), but the mechanism remains unclear.

Methods

103 stroke patients were assessed at 2 weeks after onset using Diagnostic and Statistical Manual of Mental Disorders, 5th edition and then divided into PSD and non-PSD groups. Polymorphisms of inflammatory molecules (interleukin [IL]-1β, IL-6, IL-10, IL-18, tumor necrosis factor-α [TNF-α], interferon-γ [IFN-γ] and C-reactive protein [CRP]), complete blood count parameters, splenic attenuation (SA) and splenic volume (SV) on unenhanced chest computed tomography, demographic and other clinical characteristics were obtained. Binary logistic regression model was used to analyze the associations between inflammation-related factors and the occurrence of PSD at 2 weeks after stroke.

Results

49 patients were diagnosed with PSD at 2 weeks after onset (early-onset PSD). The C/T genotypes of CRP rs2794520 and rs1205 were less in PSD group than non-PSD group (both adjusted odds ratio = 3.364; 95%CI: 1.039-10.898; p = 0.043). For CRP rs3091244, the frequency of G allele was higher (80.61% vs. 13.89%) while the frequency of A allele was lower (6.12% vs. 71.30%) in PSD patients than non-PSD patients (χ² = 104.380; p<0.001). SA of PSD patients was lower than that of non-PSD patients in the presence of CRP rs2794520 C/T genotype and rs1205 C/T genotype (both t = 2.122; p = 0.039). Peripheral monocyte count was less in PSD group than non-PSD group (adjusted odds ratio = 0.057; 95%CI: 0.005-0.686; p = 0.024).

Conclusions

CRP polymorphisms, SA based on CRP genotype, and peripheral monocytes are associated with the risk of early-onset PSD, suggesting peripheral immuno-inflammatory activities elicited by stroke in its aetiology.

Anti-depression effectiveness of essential oil from the fruits of Zanthoxylum bungeanum maxim. on chronic unpredictable mild stress-induced depression behavior in mice

The fruits of Zanthoxylum bungeanum Maxim. Was a popular traditional Chinese herbal medicine for pain relief, itching prevention, and diarrhea relief. The fruits of Zanthoxylum bungeanum Maxim. Essential oil (HEO) had an effect of improving anxiety and other emotional disorders. In this paper, we aim to systematically research the antidepressant effects of HEO on Chronic Mild Unpredictable Stimulation (CUMS) mice and explore the relevant molecular mechanisms. Experimental mice were exposed to CUMS for 8 weeks. Meanwhile, for 8 weeks, Sertraline hydrochloride (20 mg/kg/day) and HEO (50, 100, and 150 mg/kg/day) were administered by gavage. HEO treatment increased residence time of central zone in OFT and open-arm in EPM test but decreased immobility times in FST and TST. Moreover, HEO treatment improved the levels of 5-HT, DA, NE, and BDNF, but reduced CRF and CORT levels of the HPA axis in the hippocampus. Network pharmacology predicted the possible mechanisms for the antidepressant effects of HEO by regulation of PI3K/Akt signaling pathway. The mRNA expression of PI3K and Akt were increased, and immunofluorescence results in the hippocampus indicated that HEO treatment could increase the phosphorylation of PI3K and Akt. Besides, the viability of CORT-treated PC12 cells was significantly improved by HEO treatment. The AO-EB staining, MOMP analysis, and flow cytometry analysis results showed HEO inhibiting the CORT-induced apoptosis in PC12 cells significantly. Besides, the phosphorylation of PI3K and Akt in COTR-induced PC12 cells could increase by HEO treatment. In conclusion, HEO ameliorated depression behavior induced by CUMS, potentially via regulating HPA axis and activating PI3K/Akt signaling pathway to reduce neuronal apoptosis.

Pumpkin seed oil and zinc attenuate chronic mild stress perturbations in the cerebral cortex of rats

Purpose

This study aims to investigate the potential of pumpkin seed oil (PSO) and zinc to attenuate oxidative stress and neuroinflammation caused by chronic mild stress (CMS) in the cerebral cortex of male rats.

Design/methodology/approach

The rats were submitted to stress for six weeks and then the behavior of the rats was tested by forced swimming test (FST) and novel cage test. The treated groups were given venlafaxine (20 mg/kg), pumpkin seed oil (40 mg/kg) and zinc (4 mg/kg). The cortex homogenate was used for the detection of the oxidative stress parameters, the concentration of neurotransmitters, tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β), Na+/K+-ATPase activity, and the expression of histamine N-methyltransferase (Hnmt) and tyrosine hydroxylase (Th).

Findings

CMS causes a significant increase in immobility time in the FST and a significant decrease in the number of rearing in the novel cage test. CMS group showed a significant increase in alanine aminotransferase (ALT) activity, levels of cortisol, TNF-α, IL-1β, nitric oxide and malondialdehyde. CMS caused a significant decrease in the concentrations of serotonin, GABA, norepinephrine, and the activities of glutathione peroxidase, catalase, superoxide dismutase and Na+/K+-ATPase. CMS caused a marked reduction in the expression of Hnmt and Th in the cortex. PSO and zinc attenuated the Na+/K+-ATPase activity, oxidative parameters and neuroinflammation induced by the CMS, and this was reflected by the elevation of the concentration of neurotransmitters and reduction of cortisol and ALT, in addition to the behavior normalization. PSO and zinc attenuated the CMS by improving the antioxidant milieu and anti-inflammatory status of the cerebral cortex.

Originality/value

There are no studies on the effect of pumpkin seed oil on depression

Neurotransmitters-Key Factors in Neurological and Neurodegenerative Disorders of the Central Nervous System

Neurotransmitters are molecules that amplify, transmit, and convert signals in cells, having an essential role in information transmission throughout the nervous system. Hundreds of such chemicals have been discovered in the last century, continuing to be identified and studied concerning their action on brain health. These substances have been observed to influence numerous functions, including emotions, thoughts, memories, learning, and movements. Thus, disturbances in neurotransmitters' homeostasis started being correlated with a plethora of neurological and neurodegenerative disorders. In this respect, the present paper aims to describe the most important neurotransmitters, broadly classified into canonical (e.g., amino acids, monoamines, acetylcholine, purines, soluble gases, neuropeptides) and noncanonical neurotransmitters (e.g., exosomes, steroids, D-aspartic acid), and explain their link with some of the most relevant neurological conditions. Moreover, a brief overview of the recently developed neurotransmitters' detection methods is offered, followed by several considerations on the modulation of these substances towards restoring homeostasis.

Overtraining Syndrome as a Complex Systems Phenomenon

The phenomenon of reduced athletic performance following sustained, intense training (Overtraining Syndrome, and OTS) was first recognized more than 90 years ago. Although hundreds of scientific publications have focused on OTS, a definitive diagnosis, reliable biomarkers, and effective treatments remain unknown. The present review considers existing models of OTS, acknowledges the individualized and sport-specific nature of signs/symptoms, describes potential interacting predisposing factors, and proposes that OTS will be most effectively characterized and evaluated via the underlying complex biological systems. Complex systems in nature are not aptly characterized or successfully analyzed using the classic scientific method (i.e., simplifying complex problems into single variables in a search for cause-and-effect) because they result from myriad (often non-linear) concomitant interactions of multiple determinants. Thus, this review 1) proposes that OTS be viewed from the perspectives of complex systems and network physiology, 2) advocates for and recommends that techniques such as trans-omic analyses and machine learning be widely employed, and 3) proposes evidence-based areas for future OTS investigations, including concomitant multi-domain analyses incorporating brain neural networks, dysfunction of hypothalamic-pituitary-adrenal responses to training stress, the intestinal microbiota, immune factors, and low energy availability. Such an inclusive and modern approach will measurably help in prevention and management of OTS.

Novel Molecular Targets of Antidepressants

Antidepressants target a variety of proteins in the central nervous system (CNS), the most important belonging to the family of G-protein coupled receptors and the family of neurotransmitter transporters. The increasing number of crystallographic structures of these proteins have significantly contributed to the knowledge of their mechanism of action, as well as to the design of new drugs. Several computational approaches such as molecular docking, molecular dynamics, and virtual screening are useful for elucidating the mechanism of drug action and are important for drug design. This review is a survey of molecular targets for antidepressants in the CNS and computer based strategies to discover novel compounds with antidepressant activity.

Mapping the structure of depression biomarker research: A bibliometric analysis

BACKGROUND

Depression is a common mental disorder and the diagnosis is still based on the descriptions of symptoms. Biomarkers can reveal disease characteristics for diagnosis, prognosis, and treatment. In recent years, many biomarkers relevant to the mechanisms of depression have been identified. This study uses bibliometric methods and visualization tools to analyse the literature on depression biomarkers and its hot topics, and research frontiers to provide references for future research.

METHODS

Scientific publications related to depression biomarkers published between 2009 and 2022 were obtained from the Web of Science database. The BICOMB software was used to extract high-frequency keywords and to construct binary word-document and co-word matrices. gCLUTO was used for bicluster and visual analyses of high-frequency keywords. Further graphical visualizations were generated using R, CiteSpace and VOSviewer software.

RESULTS

A total of 14,403 articles related to depression biomarkers were identified. The United States (34.81%) and China (15.68%), which together account for more than half of all publications, can be considered the research base for the field. Among institutions, the University of California, University of London, and Harvard University are among the top in terms of publication number. Three authors (Maes M, Penninx B.W.J.H., and Berk M) emerged as eminent researchers in the field. Finally, eight research hotspots for depression biomarkers were identified using reference co-citation analysis.

CONCLUSION

This study used bibliometric methods to characterize the body of literature and subject knowledge in the field of depression biomarker research. Among the core biomarkers of depression, functional magnetic resonance imaging (fMRI), cytokines, and oxidative stress are relatively well established; however, research on machine learning, metabolomics, and microRNAs holds potential for future development. We found "microRNAs" and "gut microbiota" to be the most recent burst terms in the study of depression biomarkers and the likely frontiers of future research.

Biomarkers of Post-COVID Depression

The COVID-19 pandemic is spreading around the world and 187 million people have already been affected. One of its after-effects is post-COVID depression, which, according to the latest data, affects up to 40% of people who have had SARS-CoV-2 infection. A very important issue for the mental health of the general population is to look for the causes of this complication and its biomarkers. This will help in faster diagnosis and effective treatment of the affected patients. In our work, we focused on the search for major depressive disorder (MDD) biomarkers, which are also present in COVID-19 patients and may influence the development of post-COVID depression. For this purpose, we searched PubMed, Scopus and Google Scholar scientific literature databases using keywords such as 'COVID-19', 'SARS-CoV-2', 'depression', 'post-COVID', 'biomarkers' and others. Among the biomarkers found, the most important that were frequently described are increased levels of interleukin 6 (IL-6), soluble interleukin 6 receptor (sIL-6R), interleukin 1 β (IL-1β), tumor necrosis factor α (TNF-α), interferon gamma (IFN-γ), interleukin 10 (IL-10), interleukin 2 (IL-2), soluble interleukin 2 receptor (sIL-2R), C-reactive protein (CRP), Monocyte Chemoattractant Protein-1 (MCP-1), serum amyloid a (SAA1) and metabolites of the kynurenine pathway, as well as decreased brain derived neurotrophic factor (BDNF) and tryptophan (TRP). The biomarkers identified by us indicate the etiopathogenesis of post-COVID depression analogous to the leading inflammatory hypothesis of MDD.