Molecular pathways of major depressive disorder converge on the synapse

Association of uric acid/high-density lipoprotein cholesterol ratio (UHR) with depression risk in US adults: A cross-sectional study

BACKGROUND

The uric acid/high-density lipoprotein cholesterol ratio (UHR) is a new indicator of inflammation and metabolism that has been found to be strongly associated with several chronic diseases. However, the relationship between the UHR and depression has not been studied to date.

METHODS

The study included a total of 16,920 participants aged 20 years and older from NHANES 2005-2018. Logistic regression models with weights were used to evaluate the association between quintile levels of UHR and depression risk.

RESULTS

Elevated UHR levels were significantly associated with a 52 % increased risk of depression after multivariable adjustment (Q5 OR: 1.52, 95 % CI: 1.26, 1.83, P-trend <0.001). We found a significant interaction between UHR level and sex (P = 0.018), but no significant interaction between UHR and other factors, including age, smoking, alcohol consumption, education level, marital status, household income poverty ratio and physical activity. Stratified analyses of these factors showed that high levels of UHR were significantly associated with risk of depression in groups who were female, younger, had never smoked, were alcohol drinkers, had higher levels of education, were cohabiters, had the highest and lowest household incomes, and were physically active.

CONCLUSION

In conclusion, UHR was positively associated with an increased risk of depression, suggesting that UHR levels can be used as a comprehensive indicator for the early identification of depression risk.

Peripheral blood miR-16-5p as a potential biomarker for distinguishing unmedicated bipolar disorder type II from major depressive disorder

OBJECTIVE

major depressive disorder (MDD) and bipolar disorder type II (BD-II) are difficult to distinguish clinically due to similar depressive symptoms and unrecognizable hypomania symptoms in the early stages. The study aims to identify these two disorders in the early stages through differential expression of microRNAs.

METHODS

93 subjects including 66 unmedicated patients (33 MDD, 33 BD-II), and 27 healthy controls (HC) were enrolled. At the time of enrollment, all subjects' demographic data, HAMD, HCL-32, and YMRS scales were assessed. 5 ml of peripheral blood for all subjects was collected for microRNA second-generation sequencing. MicroRNA differential expression, target gene GO and KEGG analyses were performed.

RESULTS

No statistical differences in demographic data were found except for age (BD-II < MDD, P = 0.002). In terms of clinical data, there are differences in the course of the disease (BD-II > MDD, P = 0.037) and the HCL-32 (BD-II > MDD, P < 0.01). A variance analysis of microRNA expressions across all three groups identified eight highly expressed differential miRNAs (P < 0.001), Pairwise comparisons revealed that the expression level of miR-16-5p was lower in both MDD group (P < 0.05) and BD-II group (P < 0.001) than in HC group, and it was even lower in BD-II group compared to MDD group (P < 0.01). The area under the curve (AUC) for miR-16-5p in differentiating BD-II from MDD groups was 0.723 (P = 0.003).

CONCLUSIONS

Peripheral blood miR-16-5p may serve as a potential biomarker for distinguishing unmedicated BD-II from MDD patients.

Exploring the neuroplasticity hypothesis in depression: The role of traditional Chinese herbal medicine

BACKGROUND

Depression is a mental disorder that seriously affects global health, and its pathogenesis involves multiple factors, including changes in neuroplasticity. The neuroplasticity hypothesis suggests that there may be functional and structural abnormalities in synaptic plasticity, neuronal generation and maturation, neural circuits and related signaling pathways in patients with depression. Traditional Chinese medicine (TCM), as a traditional treatment method, has attracted increasing attention in the field of neuropharmacology in recent years due to its high efficiency and low toxicity.

PURPOSE

This article will systematically review the neuroplasticity changes in key brain regions and related mechanisms of depression, with a focus on the recent research progress in traditional Chinese herbal medicine intervention on neuroplasticity, to provide new ideas and strategies for the treatment of depression.

METHODS

To investigate the effects and mechanisms of Chinese herbal medicine's antidepressant actions through promoting neuroplasticity, data were collected from CNKI, Web of Science, PubMed, and ScienceDirect through November 2024. In addition, a classification and summary of Chinese herbal medicine to restore neuroplasticity was performed.

RESULTS

Brain regions such as the hippocampus, prefrontal cortex, and amygdala are closely associated with neuroplasticity in depression. Moreover, the glutamatergic system, neurotrophic factors, monoamine neurotransmitters, and neuroinflammation are the main mechanisms that regulate neuroplasticity. The benefits of extracts, active ingredients, and formulas of Chinese herbal medicine on neuroplasticity through multiple pathways have been widely reported.

CONCLUSION

The enhancement of neuroplasticity and regulation of its endogenous molecular pathways offer novel therapeutic paradigms for employing botanical interventions in depression management. Future investigations should prioritize mechanistic exploration through integrated preclinical-clinical approaches to elucidate how Chinese herbal formulations modulate neuroplasticity, which decipher the multi-target pharmacological actions underlying botanical antidepressants' therapeutic efficacy.

Heterocycle-fused phenylcyclohexylamines as novel multi-target antagonists of N-methyl-D-aspartate (NMDA) receptor and monoamine transporter for treating depression

Simultaneously modulating the glutamatergic and monoaminergic systems represents a promising strategy for treating depression. In this study, a series of multi-target antagonists targeting both NMDAR and monoamine transporters (SERT, DAT, and NET) was designed and evaluated for their antidepressant potential in vitro and in vivo. Among these heterocycle-fused phenylcyclohexylamine derivatives, compound A16 demonstrated potent and relatively balanced multi-target activity (A16: IC50(NMDAR): IC50(SERT): IC50(DAT): IC50(NET) = 1.8:1.0:1.9:1.3) compared to the lead compound S1. Pharmacokinetic studies revealed that A16 exhibited moderate clearance in microsomes and favorable oral brain exposure in mice. In vivo assessments showed that A16 and its R-isomer A17 exhibited significant antidepressant-like effects in the forced swim test and tail suspension test in mice. Notably, A17 demonstrated significant antidepressant-like effects at doses as low as 1 mg/kg, with no indication of addiction risk at 20 mg/kg. Collectively, these findings identify A17, a heterocycle-fused phenylcyclohexylamine as a promising scaffold for developing non-addictive, rapid-acting antidepressants.

NRXN3-NLGN1 complex influences the development of depression induced by maternal separation in rats

Early-life stress (ELS) increases the risk of major depressive disorder in children and adolescents. However, the molecular and cellular mechanisms of major depressive disorder (MDD) induced by ELS are poorly understood. Here, we establish a stress model in rats in which maternal separation stress (MS) during the postnatal period increases susceptibility to restraint stress (RS) later in life. In terms of mechanism, MS causes long-lasting synaptic plasticity alterations in rats, which is accompanied by reduced branch and spine lengths in the hippocampus. We identified the role of the cell adhesion factor neurexin 3 (NRXN3) and its ligand neuroligin 1 (NLGN1) as mediators of these effects. NRXN3 and NLGN1 downregulation in the hippocampus occurred prior to the observed synaptic changes and depression-related behaviors. In conclusion, NRXN3 is involved in the development of depression induced by maternal separation, and the specific mechanism involves the NRXN3-NLGN1 complex, which can mediate synaptic plasticity and increase susceptibility todepression.

Targeting ApoE-KCC2 Signaling Rescues GABAergic Synaptic Dysfunction and Depression-like Behaviors in Mice

Apolipoprotein E (ApoE) has been implicated in neurodegenerative diseases; however, its function and underlying mechanisms in depression remain elusive. In this study, we employed chronic social defeat stress (CSDS) to establish a mouse model of depression and observed significantly reduced ApoE expression in the hippocampus. By leveraging ApoE knockout (ApoE-/- ) and knockdown (ApoE-KD) mouse models, we demonstrated that ApoE deficiency induced depression-like behaviors, which were closely associated with impaired GABAergic synaptic transmission and down-regulation of ApoE receptors and K+-Cl- cotransporter 2 (KCC2). In addition, we found an interaction between KCC2 and the ApoE receptor low-density lipoprotein receptor (LDLR) through coimmunoprecipitation analysis. Moreover, overexpression of ApoE or targeted activation of GABAergic neurons in the hippocampus significantly reversed depression-like behaviors in both CSDS-exposed and ApoE-KD mice. Lastly, treatment with KCC2 activators, CLP290 and CLP257, restored the expression levels of KCC2 and the GABAAR α1 subunit, significantly alleviating depression-like behaviors induced by CSDS or ApoE-KD. Together, our results elucidate the pivotal role of ApoE in the pathophysiology of depression and highlight the ApoE-KCC2 signaling pathway as a potential target for developing innovative antidepressant therapies.

Phytochemicals encouraging neurotrophic pathways: brain-derived neurotrophic factors as molecular targets in depression

A complex neuropsychiatric disorder, major depressive disorder (MDD), is linked to dysregulation of neurotrophic factors, neurotransmitter imbalances, and structural changes in the brain. A lack of brain-derived neurotrophic factor (BDNF) has been linked to the pathophysiology of depression. BDNF is critical for neuroplasticity, neuronal viability, and synaptic efficacy. The neurotrophic hypothesis of depression proposes that treatment strategies targeting the BDNF signaling pathway may be promising therapeutic strategies. While traditional antidepressants such as selective serotonin reuptake inhibitors (SSRIs) are known to modulate the expression of BDNF, their use is limited in effectiveness, and a delayed onset of action occurs in many patients. Recent studies have focused on the possibility of the use of phytochemicals as antidepressant agents to target the BDNF pathway. Phytochemicals such as curcumin, resveratrol, quercetin, EGCG, hesperidin, and baicalin have demonstrated neuroprotective and antidepressant-like properties by modulating several key signaling pathways, including the PI3K/Akt/mTOR, MAPK/ERK, and NF-κB/CREB pathways. These compounds increase BDNF expression, promote synaptic plasticity, and mitigate neuroinflammation, contributing to improved mood and cognitive function. Although phytochemicals show considerable preclinical and clinical activity, their clinical usage is limited and characterized by several problems, such as poor bioavailability, poor blood‒brain barrier permeability, and variability in therapeutic response. Several formulation strategies, such as structural modifications and nanoencapsulation, are being explored to improve their pharmacokinetic profiles. These results also highlight the need for larger clinical trials, combination therapies with pharmaceuticals, and mechanistic studies that may clarify the role of phytochemicals in establishing these products as effective and well-tolerated treatments for depression. This narrative review addresses the gap in understanding how plant-derived bioactive compounds can modulate neurotrophic pathways in depression and explores emerging strategies for translating these findings into therapies.

Association between atopic disorders and mental ill health: a UK-based retrospective cohort study

OBJECTIVE

To examine the mental ill health burden associated with allergic and atopic disorders, in a UK primary care cohort.

DESIGN

Population-based retrospective open cohort study.

SETTING

United Kingdom.

PARTICIPANTS

2 491 086 individuals with primary-care recorded atopic disorder (food allergy, drug allergy, anaphylaxis, urticaria, allergic rhino-conjunctivitis) diagnosis were matched by sex, age (± 2 years), and socio-economic deprivation (Townsend quintile score) at index to 3 120 719 unexposed individuals. The mean age of exposed patients at cohort entry was 39.42 years (SD (SD) 23.65) compared with 35.81 years (SD 22.17) for unexposed patients.

MAIN OUTCOME MEASURES

The primary outcome was a composite of mental ill health (severe mental illness, anxiety, depression, eating disorders, obsessive-compulsive disorder (OCD), and self-harm), identified using Read codes. Cox regression was used to estimate adjusted hazard ratios with 95% confidence intervals for the composite mental ill health outcome and each of the individual mental health disorders. Covariates adjusted for were age, sex, alcohol use, smoking status, body mass index (BMI), Townsend deprivation quintile score, asthma exposure, and eczema exposure at baseline.

RESULTS

Between first January 1995 to 31st January 2022, a total of 2 491 086 eligible individuals were identified with a primary care recorded diagnosis of atopic disease and were matched to 3 120 719 unexposed individuals. 229 124 exposed individuals developed a mental ill health outcome during the study period (incidence ratio (IR) 144.13 per 10 000 person-years) compared with 203 450 in the unexposed group (IR 117.82 per 10 000 person-years). This translated to an adjusted hazard ratio (aHR) of 1.16 (95% CI 1.15 to 1.17). Notably, the risk of anxiety was greatest, aHR 1.22 (95% CI 1.21 to 1.23). Our findings were robust to a sensitivity analysis, where individuals were also matched for asthma and eczema.

CONCLUSION

There is an increased risk of mental ill health disorders among patients with diagnosis of an allergic and atopic disorders. There is a need to consider dual delivery of allergy and psychology services to optimise mental well-being among this cohort.

The involvement of the synaptic vesicle cycle in homocysteine induced neurotoxicity in vitro and in vivo

Homocysteine (Hcy), a sulfur-containing amino acid derived from methionine, has been shown to be a significant and modifiable risk factor for various neurological disorders, including stroke, Parkinson's disease, Alzheimer's disease, and elderly depression. However, there is currently a lack of comprehensive understanding regarding the molecular mechanisms underlying Hcy-induced neurotoxicity. Therefore, this study aimed to establish rat and cell models of Hcy intervention in order to elucidate the underlying mechanism of neurotoxicity. Our research findings demonstrate that Hcy induces depressive - like symptoms in normal Sprague-Dawley rats. Pathological damage and apoptosis were detected in the DG, CA3, and CA1 regions of the hippocampus, along with the cortical area. Moreover, synaptic structural impairment was observed within the hippocampal. Simultaneously, Hcy promotes neuronal apoptosis and LDH leakage in mouse neuroblastoma (N2a) cells. Furthermore, we conducted mRNA microarray analysis to investigate differences in mRNA expressions and utilized Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis for gene function annotations in Hcy-treated N2a cells. The results highlighted significant alterations in 457 mRNAs in the Hcy-treated group compared to the Control group. Among the differentially expressed genes (DEGs), a total of 155 were found to be significantly up-regulated, while the remaining 302 were down-regulated. Furthermore, it was observed that four genes (snap25, cplx1, slc32a1 and atp6v1e2) related to the synaptic vesicle cycle exhibited decreased expression in Hcy-treated N2a cells compared to the Control group. The expression levels of these four genes, as well as their corresponding proteins, were subsequently confirmed using RT-qPCR and western blot analysis, respectively. In conclusion, this study shed light on the detrimental impact of hyperhomocysteinemia on the nervous system, particularly with regard to the synaptic vesicle cycle.

Autophagy-Unlocking New Dimensions in the Pathology and Treatment of Depression

Depression is a widespread mental disorder whose impact on an individual's health extends far beyond the psychological dimension. As a disease with a significant burden, the effective treatment of depression has become a major challenge for global public health. Although several hypotheses have been proposed for the pathogenesis of depression, its pathophysiological mechanisms remain complex and not yet fully understood. Recent studies suggest that dysfunctional autophagy may play an important role in the development of depression. Autophagy, as an important intracellular degradation mechanism, maintains neuronal function and health by removing excess proteins and damaged organelles. Current evidence suggests that the regulation of autophagic processes may provide new potential targets for the treatment of depression. In this paper, we review the pharmacological mechanisms of autophagy by different antidepressant drugs and the abnormal changes in autophagy in patients with depression and in multiple models. Importantly, we focus on the role of autophagy in different pathological mechanisms of depression and discuss current limitations as well as potential directions for future research.

Elucidating the Antidepressant-Like Effect of Tannic Acid in Mice: Modulation of Serotonergic System and Pro-Inflammatory Mediators

This study aimed to evaluate the therapeutic action of tannic acid (TA) in male Swiss mice by investigating: i) the involvement of the serotonergic system in the acute TA antidepressant-like action per se using pharmacological tools, and ii) the neuroprotective activity of TA in a lipopolysaccharide (LPS)-induced depressive-like behavior. For mechanistic investigation of the acute TA antidepressant-like action, mice received i.p. the serotoninergic receptor antagonists: WAY-100135 (5-HT1 A antagonist), ketanserin (5-HT2 A/2 C antagonist), or ondansetron (5-HT3 antagonist); 15 min later, TA or water was given by gavage. After 1 h, mice were subjected to a tail suspension test (TST). TA in different doses was tested in acute open field test (OFT), TST, and forced swimming test (FST). In the LPS protocol, animals were pretreated once daily with TA (60 or 120 mg/kg), fluoxetine (20 mg/kg) or vehicle for 7 days. On the 7th day, mice received a single injection of LPS (830 μg/kg, i.p.). After 24 h, OFT and TST were assessed. Behavioral data concerning the acute antidepressant-like effects of TA demonstrated that this tannin acts via 5-HT1 A and 5-HT2 A/2 C receptors. Besides, monoamine oxidase A (MAO-A) in vitro activity was determined in total brain; the polyphenol action was able to decrease enzyme activity. In the LPS-induced depression model, TA prevented the increase in LPS-induced immobility time in the TST, downregulated the expression of NF-κB and IL-1β, and modulated MAO-A activity in the cerebral cortex. In conclusion, TA exhibited neuroprotective and antidepressant-like activities in mice, positioning it as a promising candidate for depression therapeutics.

Psilocybin mitigates behavioral despair and cognitive impairment in treatment-resistant depression model using wistar kyoto rats

Major depressive disorder (MDD) is a leading cause of disability that affects over 300 million people globally. Despite multiple antidepressant trials, approximately one-third of MDD patients remain symptomatic, progressing to treatment-resistant depression (TRD). This persistence possibly is due to the multifaceted etiology of TRD, encompassing biological, psychological, and environmental factors. Chronic stress, prevalent in modern life, significantly contributes to mental health disorders and complicates TRD treatment. This study investigated psilocybin as a potential TRD treatment using a diathesis-stress animal model. Twenty-two male Wistar-Kyoto (WKY) rats were divided into control and stress groups, with the stress group further subdivided to receive either sham treatment or psilocybin as early intervention. Behavioral assessments demonstrated a significant and sustained beneficial effect of psilocybin on behavioral despair and cognitive impairment. Biochemical analyses revealed psilocybin-induced increases in thyroid-stimulating hormone (TSH) levels without significant changes in the hypothalamic-pituitary-adrenal (HPA) axis. The ability of psilocybin to counter stress-induced TSH reductions suggested that TSH may serve as a proxy marker of therapeutic response, although its causal role in mood regulation remains unclear. Additionally, following psilocybin administration, changes in cannabinoid receptor type I (CB1R) suggest a potential modulation of psilocybin intervention on the component of the endocannabinoid system (ECS), though causal links remain unconfirmed without antagonist studies. These findings highlight the potential of psilocybin to treat TRD through the targeting of previously unexplored biological pathways.

Single-Nucleus Transcriptomics of the Nucleus Accumbens Reveals Cell-Type-Specific Dysregulation in Adolescent Macaques with Depressive-Like Behaviors

Adolescent depression is increasingly recognized as a serious mental health disorder with distinct clinical and molecular features. Using single-nucleus RNA sequencing, we identified cell-specific transcriptomic changes in the nucleus accumbens (NAc), particularly in astrocytes, of adolescent macaques exhibiting depressive-like behaviors. The level of diacylglycerol kinase beta was significantly reduced in neurons and glial cells of depressed macaques, while FKBP5 levels increased in glial cells. Disruption of GABAergic synapses and disruption of D-glutamine and D-glutamate metabolism were linked to depressive phenotypes in medium spiny neurons (MSNs) and subtypes of astrocytes. Communication pathways between astrocytes and D1/D2-MSNs were also disrupted, involving factors like bone morphogenetic protein-6 and Erb-B2 receptor tyrosine kinase-4. Bulk transcriptomic and proteomic analyses corroborated these findings, and FKBP5 upregulation was confirmed by qRT-PCR, western blotting, and immunofluorescence in the NAc of rats and macaques with chronic unpredictable mild stress. Our results highlight the specific roles of different cell types in adolescent depression in the NAc, offering potential targets for new antidepressant therapies.

Elevated NEGR1 in brain induces anxiety or depression-like phenotypes and synaptic dysfunction

Single nucleotide polymorphisms (SNPs) within 1p31.1 region have shown significant associations with depression, and our prior functional genomics pinpointed a regulatory variant rs3101339 among them. However, its precise role in depression pathogenesis remains elusive. In this study, we employed a series of analytical and functional approaches, including regulatory element annotation, brain expression quantitative trait loci (eQTL), reporter gene assay, electrophoretic mobility shift assay (EMSA), and precise genome editing. Our results confirmed that rs3101339 is a causal variant within 1p31.1 with its risk allele C upregulating NEGR1 expression. To further investigate the consequences of NEGR1 upregulation, we overexpressed NEGR1 in specific region of the mouse brain (including medial prefrontal cortex (mPFC) and ventral hippocampus (vHIP)) using stereotaxic injection. Behavioral assessments revealed that elevated NEGR1 levels in the brain, particularly in the vHIP, resulted in working memory impairment as well as anxiety- and depression-like behaviors in mice. Neuronal sparse labeling assay and transmission electron microscopy revealed that NEGR1 overexpressing in the vHIP leads to dendritic spine loss and synaptic ultrastructure abnormality. Immunoprecipitation-mass spectrometry (IP-MS) further identified 67 high-confidence proteins that interacted with NEGR1, many of which are involved in neurotransmitter exocytosis and synaptic vesicle endocytosis. Transcriptomic profiling revealed 94 differentially expressed genes in NEGR1-OE (vHIP) mice compared to control mice (P adj < 0.05), which were enriched in myelination-related signaling pathways (such as myelination, ensheathment of neurons, axon ensheathment in central nervous system, etc.). Together, our findings implicated that the overexpression of the NEGR1 gene in the mouse brain as a potential driver of anxiety- or depression-like phenotypes potentially through impairing synaptic function and myelination.

RIPK3-MLKL dependent necroptosis mediates depressive-like behavior by facilitating neuroinflammation

BACKGROUND

Neuroinflammation is a critical pathophysiological mechanism of depression. But the sources and processes involved remain unclear. Recent reports suggest that necroptosis with pro-inflammatory properties may facilitate inflammation. Therefore, we investigated the potential role of necroptosis-associated neuroinflammation in depression.

METHODS

Depression model mice induced by intraperitoneal injection of lipopolysaccharide (LPS) were treated with RIPK1 inhibitor Necrostatin-1 s (Nec-1 s, 6 mg/kg), RIPK3 inhibitor GSK'872 (6 mg/kg) or intracerebroventricular injection of MLKL inhibitor GW806742X (5 μL of 200 μmol/L). Depressive-like behaviors were assessed using sucrose preference test and tail suspension test. Serum inflammatory cytokines were detected by ELISA, while glial biomarkers were determined by western blots. Hematoxylin & eosin and immunohistochemical staining were utilized to identify morphological characteristics of necroptotic cells in the hippocampus and prefrontal cortex. Further, specific molecules involved in necroptotic pathway were measured by immunoblots.

RESULTS

Mice treated with LPS exhibited depressive-like behaviors, as well as increased inflammatory cytokines, enhanced MLKL phosphorylation, and decreased cleaved Caspase-8 levels in hippocampus. GSK'872 rather than Nec-1 s exhibited significant antidepressant effects. Although necroptosis was present in both the hippocampus and prefrontal cortex, neuroinflammation was mainly manifested in the hippocampus. Additionally, GSK'872 restored the elevated levels of IL-1β, TNF-α, and HMGB1 in the serum and hippocampus of model mice, and simultaneously ameliorated necroptosis. However, neither GSK'872 nor Nec-1 s had sufficient effect on Caspase-8 and microgliosis. Furthermore, intracerebroventricular injection of GW806742X improved depressive-like behavior and neuroinflammation in hippocampus.

CONCLUSION

This study provides novel evidence that hippocampal RIPK3-MLKL-dependent necroptosis mediates depressive-like behavior induced by inflammatory stress. During this process, necroptosis may facilitate neuroinflammation by promoting the release of HMGB1. Interventions targeting this pathway may help treat depression with an inflammatory phenotype.

Predicting depression severity using machine learning models: Insights from mitochondrial peptides and clinical factors

Depression presents a significant challenge to global mental health, often intertwined with factors including oxidative stress. Although the precise relationship with mitochondrial pathways remains elusive, recent advances in machine learning present an avenue for further investigation. This study employed advanced machine learning techniques to classify major depressive disorders based on clinical indicators and mitochondrial oxidative stress markers. Six machine learning algorithms, including Random Forest, were applied and their performance was investigated in balanced and unbalanced data sets with respect to binary and multiclass classification scenarios. Results indicate promising accuracy and precision, particularly with Random Forest on balanced data. RF achieved an average accuracy of 92.7% and an F1 score of 83.95% for binary classification, 90.36% and 90.1%, respectively, for the classification of three classes of severity of depression and 89.76% and 88.26%, respectively, for the classification of five classes. Including only oxidative stress markers resulted in accuracy and an F1 score of 79.52% and 80.56%, respectively. Notably, including mitochondrial peptides alongside clinical factors significantly enhances predictive capability, shedding light on the interplay between depression severity and mitochondrial oxidative stress pathways. These findings underscore the potential for machine learning models to aid clinical assessment, particularly in individuals with comorbid conditions such as hypertension, diabetes mellitus, and cardiovascular disease.

Flavokawain B ameliorates depressive-like behaviors by inhibiting neddylation in the ventral hippocampus

Depression is a widespread and serious mental illness. Recent evidence suggests that post-translational modifications, particularly neddylation, play a significant role in the pathophysiology of mood disorders. Neddylation, similar to ubiquitination, involves the attachment of NEDD8 to target proteins, regulating their function. However, its role in depression remains unclear. This study aimed to explore the antidepressant effects of flavokawain B (FKB), a novel neddylation inhibitor, in mouse models of depression induced by lipopolysaccharide (LPS) and chronic unpredictable mild stress (CUMS). We assessed depressive- and anxiety-like behaviors using the sucrose preference test (SPT), open-field test (OFT), forced swimming test (FST), and tail suspension test (TST). Neddylation-related protein expression (NEDD8, NAE1, UBA3, UBC12) was measured in the dorsal and ventral hippocampus (DH, VH), prelimbic cortex (PrL), and nucleus accumbens (NAc). Results showed that FKB reversed the activation of neddylation anxiety- and depressive-like behaviors in both LPS- and CUMS-treated mice. The LPS and CUMS experimental paradigms only impacted the neddylation pathway in the VH and not other brain regions (DH, PrL, IL, NAc). In conclusion, these findings suggest that FKB ameliorates depressive-like behaviors by targeting the NAE1/UBA3/UBC12 pathway in the VH, providing a potential therapeutic approach for depression.

Altered proteomics in brain extracellular vesicles from depressed individuals who died by suicide implicates synaptic processes

BACKGROUND

Major depressive disorder (MDD) is a common and debilitating disorder whose molecular neurobiology remains unclear. Extracellular vesicles (EVs) are small vesicles that are released by cells and are involved in intercellular communication. They carry bioactive molecules, such as proteins, that reflect the state of their cell of origin. In this study, we sought to investigate the proteomic cargo of brain EVs from depressed individuals as compared to EVs from matched neurotypical individuals. In addition, we investigated how the EV proteomic cargo compares to the proteomic profile of bulk tissue.

METHODS

Using mass spectrometry and label-free quantification, we investigated the EV and bulk tissue protein profile from anterior cingulate cortex samples from 86 individuals. We performed differential expression analysis to compare cases and controls, followed by in silico analysis to determine potential implicated functions of dysregulated proteins.

RESULTS

Extracellular vesicles display distinct proteomic profiles compared to bulk tissue. Differential expression analysis showed that 70 proteins were differentially packaged in EVs in MDD, while there was no significant difference in protein levels between groups in bulk tissue. In silico analysis points to a strong role of these differential EV proteins in synaptic functions.

CONCLUSION

To our knowledge, this is the first study to profile EV proteins in depression, providing novel information to better understand the pathophysiology of MDD. This work paves the way for discovering new therapeutic targets for MDD and prompts more investigations into EVs in MDD and other psychiatric disorders.

Neuron-Derived Extracellular Vesicles: Emerging Regulators in Central Nervous System Disease Progression

The diagnosis and exploration of central nervous system (CNS) diseases remain challenging due to the blood-brain barrier (BBB), complex signaling pathways, and heterogeneous clinical manifestations. Neurons, as the core functional units of the CNS, play a pivotal role in CNS disease progression. Extracellular vesicles (EVs), capable of crossing the BBB, facilitate intercellular and cell-extracellular matrix (ECM) communication, making neuron-derived extracellular vesicles (NDEVs) a focal point of research. Recent studies reveal that NDEVs, carrying various bioactive substances, can exert either pathogenic or protective effects in numerous CNS diseases. Additionally, NDEVs show significant potential as biomarkers for CNS diseases. This review summarizes the emerging roles of NDEVs in CNS diseases, including Alzheimer's disease, depression, traumatic brain injury, schizophrenia, ischemic stroke, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. It aims to provide a novel perspective on developing therapeutic and diagnostic strategies for CNS diseases through the study of NDEVs.

Structural alterations after repetitive transcranial magnetic stimulation in depression and the link to neurotransmitter profiles

BACKGROUND

Repetitive Transcranial Magnetic Stimulation (rTMS) is widely used to treat depression, showing good efficacy and tolerability. However, the neurobiological mechanisms of its antidepressant effects remain unclear. This study explores the potential impact of rTMS on brain structure in depressed patients and its link to neurotransmitter systems.

METHODS

Thirty-six MDD patients were randomized to receive 5 times per week for 3 weeks of active or sham rTMS targeting the dorsolateral prefrontal cortex (DLPFC) within a double-blind, sham-controlled trial. The Hamilton Depression Rating Scale-17 items (HAMD-17) was used to assess depressive symptoms at baseline and the end of 1 W, 2 W and 3 W after treatment. We analyzed the differences in efficacy between the two groups of patients at different time points, and the grey matter changes of the brain before and after treatment in both groups. In addition, we analyzed the spatial correlations between abnormal grey matter and the neurotransmitter receptors and transporters map.

RESULTS

Both the active and sham groups showed significant improvement in depression and anxiety symptoms following rTMS treatment, with the Active group demonstrating greater improvement. Additionally, the Active group exhibited increased grey matter volume in regions associated with the frontal-limbic network, and these changes were significantly correlated with the spatial distribution of D1 receptors.

CONCLUSION

This study suggests that rTMS targeting the left DLPFC produces antidepressant effects by enhancing structural plasticity in the frontal-limbic network, and that dopamine system modulation may underlie rTMS therapeutic effects. These findings provide insight into the neurobiological basis of rTMS for depression treatment.

Multi-omics analysis reveals mechanisms of FMT in Enhancing antidepressant effects of SSRIs

OBJECTIVE

This study explores the behavioral and molecular biological impacts of Fecal Microbiota Transplantation (FMT) on depressive mice unresponsive to treatment with Selective Serotonin Reuptake Inhibitors (SSRIs).

METHODS

Healthy male C57BL/6 mice were used to establish a depression model through chronic restraint stress, treated with fluoxetine, and categorized into Response and Non-response groups. An FMT treatment was added to the Non-response group. Behavioral tests were conducted to assess symptoms of depression. The gut microbiome, plasma metabolites, and hippocampal tissue gene expression and function changes were analyzed using 16S rRNA gene sequencing, LC-MS, and RNA sequencing.

RESULTS

FMT significantly improved the depressive symptoms in SSRIs-resistant mice. There was a partial restoration in the diversity and structure of the gut microbiota in the FMT group. Compared to the Non-response group, significant changes were noted in the metabolomic profiles of the FMT group, identifying various differential metabolites. Functional annotations indicated that these metabolites are involved in multiple metabolic pathways. In the Non-response group, certain gene expression levels were significantly restored. GO and KEGG enrichment analyses revealed that these differential genes mainly involve cytokine activity, receptor signaling regulation, and NOD-like receptor signaling pathways. Joint analysis suggested that FMT may exert its effects through an increase in the abundance of g__Paraprevotella, leading to decreased baicalin content and increased Tal2 expression.

CONCLUSION

FMT has potential in improving depressive symptoms unresponsive to SSRIs treatment. Its mechanism may be related to the modulation of the gut microbiota and its metabolites, subsequently affecting gene expression.

Design of anti-depressant phosphodiester amino acidic Keap1-Nrf2 protein-protein interaction inhibitors

Inhibiting the protein-protein interaction (PPI) between Keap1 and Nrf2 is theoretically an effective and safe strategy for activation of Nrf2 pathway to treat major depressive disorder (MDD). In this study, through bioinformatic analysis of the brain tissues and peripheral blood of MDD patients and depressive mice, we confirmed the involvement of oxidative stress, inflammation, and the Keap1-Nrf2 pathway in depression. Subsequently, we developed a series of phosphodiester amino acidic diaminonaphthalene compounds as Keap1-Nrf2 PPI inhibitors for the first time. Screening using the LPS-stimulated SH-SY5Y and BV2 cell models identified compound 4-95 showing the best anti-oxidative stress and anti-inflammatory efficacy. The ability of 4-95 to penetrate the blood-brain-barrier was significantly enhanced. In a chronic unpredictable mild stress mouse model, treatment with 4-95 effectively ameliorated anxiety and depression behavior and restored serum neurotransmitter levels by promoting the Nrf2 nuclear translocation. Consequently, oxidative stress was reduced, and the expression of synaptic plasticity biomarkers, such as postsynaptic density protein 95 (PSD95) and synapsin 1 (SYN1) were significantly increased, suggesting the recovery of neuronal function. Collectively, our findings demonstrate that the Keap1-Nrf2 PPI inhibitor holds great promise as a preclinical candidate for the treatment of depression.

The effect of mitochondrial-associated endoplasmic reticulum membranes (MAMs) modulation: New insights into therapeutic targets for depression

Depression is a prevalent mental disorder with high morbidity and mortality and its pathogenesis remains exactly unclarified. However, mitochondria and endoplasmic reticulum (ER) are two highly dynamic organelles that perform an indispensable role in the development of depression. Mitochondrial dysfunction and ER stress are recognized as vital pathological hallmarks in depression. The changes of intracellular activities such as mitochondrial dynamics, mitophagy, energy metabolism and ER stress are closely correlated with the progression of depression. Moreover, organelles interactions are conducive to homeostasis and cellular functions, and mitochondrial-associated endoplasmic reticulum membranes (MAMs) serve as signaling hubs of the two organelles and the coupling of the pathological progression. The main roles of MAMs are involved in metabolism, signal transduction, lipid transport, and maintenance of its structure and function. At present, accumulating studies elucidated that MAMs have gradually become a novel therapeutic target in treatment of depression. In the review, we focus on influence of mitochondria dysfunction and ER stress on depression. Furthermore, we discuss the underlying role of MAMs in depression and highlight natural products targeting MAMs as potential antidepressants to treat depression.

PDE4 inhibition alleviates HMGB1/C1q/C3-mediated excessive phagocytic pruning of synapses by microglia and depressive-like behaviors in mice

Microglial activation and complement-mediated synaptic pruning are involved in depression development. We previously found that the inhibition of phosphodiesterase 4 (PDE4) inhibits microglial activation and increases synaptic plasticity. However, the role of PDE4 in microglia phagocytosis and complement-mediated synaptic pruning during depression remains unclear. Here, we investigated the effect of PDE4 on the expression of complement component 1q (C1q) and C3. We also designed and synthesized a novel PDE4 inhibitor LS21013A-06 (A06), and examined whether A06 exerts antidepressant-like effects by regulating microglia phagocytosis and complement-mediated synaptic pruning. We found that treatment with high-mobility group box-1 (HMGB1) triggered an inflammatory response, enhanced levels of complement component 1q (C1q) and C3, and promoted microglial phagocytosis both in vitro and in vivo. Notably, PDE4B knockdown reduced the levels of HMGB1, C1q, and C3 in lipopolysaccharide (LPS)-treated BV2 cells. Inhibition of PDE4 by A06 reduced the levels of HMGB1, suppressed neuroinflammation and microglial phagocytosis. In addition, A06 alleviated LPS-induced depressive-like behaviors in mice, reduced the levels of HMGB1, C1q, and C3 in the hippocampus, elevated the level of postsynaptic density protein-95, and reduced excessive microglial phagocytosis and engulfment of synapses. Moreover, C1q overexpression inhibited the effects of A06 on microglial activation and synaptic pruning. In conclusion, we demonstrated for the first time that PDE4 regulates the expression of C1q/C3, and A06 reduces microglial activation and ameliorates depressive-like behavior in mice. This mechanism involves complement C1q/C3-mediated excessive microglia phagocytosis and synaptic pruning.

Tauroursodeoxycholic acid mitigates depression-like behavior and hippocampal neuronal damage in a corticosterone model of female mice

Depression, a complex mental disorder influenced by both psychological and physiological factors, predominantly affects females. Studies have indicated that elevated levels of cortisol/corticosterone (CORT) under stress conditions can lead to hippocampal neuronal damage, thereby contributing to depression. Tauroursodeoxycholic acid (TUDCA), a bile acid, possesses anti-apoptotic, antioxidant, and anti-inflammatory properties. This study aimed to investigate the protective mechanism of TUDCA against CORT-induced neuromolecular and behavioral phenotypes of depression in female mice, providing theoretical support for its use in treating female depression. The antidepressant effects of TUDCA were evaluated through a series of behavioral tests, measurement of serum neurotransmitter levels, Nissl staining of the hippocampal CA3 region, and assessment of hippocampal proteins. Behavioral results demonstrated that TUDCA exhibited antidepressant effects, as evidenced by increased sucrose preference and locomotor activity, as well as reduced immobility time in depressed mice. Furthermore, TUDCA ameliorated neurotransmitter imbalances. Nissl staining revealed that TUDCA reduced neuronal damage in depressed mice, while Western blotting results indicated that TUDCA activated the hippocampal BDNF/TrkB/CREB pathway and regulated the expression of GR-related proteins. These findings suggested that TUDCA exerted neuroprotective effects in CORT-induced neuronal damage in female depressed mice. The mechanism appeared to be related to the activation of the BDNF/TrkB/CREB signaling pathway and the modulation of GR-related protein expression.

Secondary analysis of GenRED data (Genetics of Recurrent Early-Onset major Depression) using MERLIN

The familial relevance of depression is a critical aspect, with evidence suggesting a substantial hereditary component. Investigating the inheritance patterns within families can provide valuable insights into the genetic underpinnings of depression. To gain a new perspective on the genetics underpinning of depression, we conducted a novel analysis of the Genetics of Recurrent Early-onset Depression (GenRED) dataset including 683 U.S. Caucasian families, each with one proband with recurrent early-onset major depression and at least one sibling with depression. Using the MERLIN tool, we identified 37 genomic markers with nominal significance linkage to early-onset recurrent depression. The findings differ from prior analyses of GenRED using a different analytical tool. Our findings highlight the variability and potential discrepancies that can arise from using different analytical tools on the same dataset. Given the chance of microsatellites undergoing duplication, mutations, and amplification errors, our two-point analysis can be more robust compared to the previous multipoint analysis. Also, one limitation is genetic admixture; studies with more homogenous ethnic groups are warranted.

Exploring the diagnostic potential of IL1R1 in depression and its association with lipid metabolism

Background

Depression is a complex mental disorder where oxidative stress and lipid metabolism disorders play crucial roles, yet their connection requires further exploration. This study aims to investigate the roles of oxidative stress and lipid metabolism disorders in depression using bioinformatics methods and Mendelian randomization analysis.

Methods

A differential gene expression analysis was performed on the GSE76826 dataset, followed by identification of the intersection with genes related to OS. Subsequently, support vector machine (SVM) and random forest algorithms were employed to determine the optimal division of feature variables. The diagnostic performance was evaluated using a ROC diagnostic model and Diagnostic Nomogram. Furthermore, Mendelian randomization (MR) analysis was conducted to explore the causal relationship between the gene and depression. The expression patterns of key genes in brain tissue were analyzed using the Human eFP Browser database, while their associations with metabolism-related genes were investigated using the STRING database. Finally, DrugnomeAI was utilized to assess the drug development potential of these genes, and small molecule compounds targeting them were identified through dgidb and ChEMBL databases; molecular docking studies were then conducted to evaluate their binding affinity.

Results

By conducting a comprehensive analysis of oxidative stress-related genes and depression-related target genes, we have successfully identified 12 overlapping genes. These 12 genes were selected using support vector machine and random forest algorithms. Upon analyzing the diagnostic model, it was revealed that EPAS1 and IL1R1 serve as key biomarkers for OS in depression, with IL1R1 exhibiting the highest diagnostic potential among them. Additionally, MRfen analysis suggests that IL1R1 may play a protective role against depression. Notably, this gene exhibits high expression levels in crucial brain regions such as the olfactory bulb, corpus callosum, and hippocampus. Furthermore, our findings indicate an association between IL1R1 and lipid-related genes PDGFB, PIK3R1, TNFRSFIAA NOD2, and LYN. DrugnomeAI analysis indicated promising medicinal value for ILIRI with BI 639667 demonstrating superior binding affinity among the selected small molecule drugs.

Conclusion

This study provides novel insights into the association between OS and dyslipidemia metabolism in depression, offering potential therapeutic targets for future drug development.

Plasma-Derived Small Extracellular Vesicles miR- 182 - 5p Is a Potential Biomarker for Diagnosing Major Depressive Disorder

Depression, particularly major depressive disorder (MDD), is a debilitating neuropsychiatric condition characterized by high disability rates, primarily driven by chronic stress and genetic predispositions. Emerging evidence highlights the critical role of microRNAs (miRNAs) in the pathogenesis of depression, with plasma-derived small extracellular vesicles (sEVs) emerging as promising biomarkers. In this study, we collected peripheral blood plasma samples from patients diagnosed with MDD, as assessed by the Hamilton Depression Rating scale, alongside healthy individuals serving as controls. Plasma-derived sEVs were isolated via ultracentrifugation, followed by high-throughput sequencing of miRNAs encapsulated within sEVs, and finally image acquisition and differential expression analysis. Our results revealed a significant elevation of miR-182-5p in plasma-derived sEVs from MDD patients compared to healthy controls, a finding further validated in chronic mild stress (CMS) models. Further analysis suggested that miRNAs encapsulated within sEVs may influence depression onset and progression by modulating hypothalamic-pituitary-adrenal (HPA) axis activity. These findings underscore the potential of miRNAs and their target genes as novel biomarkers, offering improved diagnostic accuracy and therapeutic efficacy for MDD.

Multiple pathways through which the gut microbiota regulates neuronal mitochondria constitute another possible direction for depression

As a significant mental health disorder worldwide, the treatment of depression has long faced the challenges of a low treatment rate, significant drug side effects and a high relapse rate. Recent studies have revealed that the gut microbiota and neuronal mitochondrial dysfunction play central roles in the pathogenesis of depression: the gut microbiota influences the course of depression through multiple pathways, including immune regulation, HPA axis modulation and neurotransmitter metabolism. Mitochondrial function serves as a key hub that mediates mood disorders through mechanisms such as defective energy metabolism, impaired neuroplasticity and amplified neuroinflammation. Notably, a bidirectional regulatory network exists between the gut microbiota and mitochondria: the flora metabolite butyrate enhances mitochondrial biosynthesis through activation of the AMPK-PGC1α pathway, whereas reactive oxygen species produced by mitochondria counteract the flora composition by altering the intestinal epithelial microenvironment. In this study, we systematically revealed the potential pathways by which the gut microbiota improves neuronal mitochondrial function by regulating neurotransmitter synthesis, mitochondrial autophagy, and oxidative stress homeostasis and proposed the integration of probiotic supplementation, dietary fiber intervention, and fecal microbial transplantation to remodel the flora-mitochondrial axis, which provides a theoretical basis for the development of novel antidepressant therapies targeting gut-brain interactions.

Exosomal Biomarkers: A Comprehensive Overview of Diagnostic and Prognostic Applications in Malignant and Non-Malignant Disorders

Exosomes are small extracellular vesicles, ranging from 30 to 150 nm, that are essential in cell biology, mediating intercellular communication and serving as biomarkers due to their origin from cells. Exosomes as biomarkers for diagnosing various illnesses have gained significant investigation due to the high cost and invasive nature of current diagnostic procedures. Exosomes have a clear advantage in the diagnosis of diseases because they include certain signals that are indicative of the genetic and proteomic profile of the ailment. This feature gives them the potential to be useful liquid biopsies for real-time, noninvasive monitoring, enabling early cancer identification for the creation of individualized treatment plans. According to our analysis, the trend toward utilizing exosomes as diagnostic and prognostic tools has raised since 2012. In this regard, the proportion of malignant indications is higher compared with non-malignant ones. To be precise, exosomes have been used the most in gastrointestinal, thoracic, and urogenital cancers, along with cardiovascular, diabetic, breathing, infectious, and brain disorders. To the best of our knowledge, this is the first research to examine all registered clinical trials that look at exosomes as a diagnostic and prognostic biomarker.

Association between depressive symptoms and premature death: An exploratory mediation analysis via mitochondrial function

BACKGROUND

Depression is a common mental health issue that can lead to various physical and psychological diseases. However, the relationship between depressive symptoms and premature death remains unclear.

METHODS

In this study, we used data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 to assess the relationship between depressive symptoms and premature mortality and the potential influence of mitochondrial function on this relationship. The Patient Health Questionnaire-9 (PHQ-9) was used to assess the severity of depressive symptoms. Mortality data were obtained from the National Death Index (NDI). Mitochondrial function was assessed by measuring methylmalonic acid (MMA) levels. Multivariate logistic regression was used to assess the association between depressive symptoms and premature mortality, controlling for demographic, lifestyle, and disease-related factors. Restricted cubic splines were plotted, and propensity score matching (PSM) was used to create balanced groups. Finally, mediation analysis was performed to investigate the mediating role of MMA in the association between depressive symptoms and premature mortality.

RESULTS

This study included a total of 6599 participants. The results showed a substantial positive association (odds ratio [OR] = 1.452; 95 % confidence interval [CI], 1.038-2.031; p < 0.05) between depressive symptoms and premature mortality. The significance of this relationship was maintained after PSM analysis (OR = 2.370; 95 % CI, 1.749-3.212; p < 0.01). Mediation analysis showed that MMA partially mediated this relationship, with a mediation proportion of 4.1 %.

CONCLUSION

This study indicates that depressive symptoms significantly increases the risk of premature death and mitochondrial dysfunction partially mediates this positive relationship. Additional prospective and experimental studies are warranted to verify these findings.

Glymphatic function and choroid plexus volume is associated with systemic inflammation and oxidative stress in major depressive disorder

BACKGROUND

Inflammatory processes were recognized as key factors in the pathophysiology of major depressive disorder (MDD). The choroid plexus (ChP) and glymphatic system played central roles in immune interactions between the brain and periphery. However, their specific roles in MDD and their relationship with systemic inflammation and oxidative stress remained unclear.

METHODS

This study finally included 665 MDD patients and 338 healthy controls. Clinical data and MRI scans were collected, and some patients also underwent blood routine and biochemical tests. ChP volume was manually segmented, and the diffusion tensor imaging along the perivascular space (DTI-ALPS) index, reflecting glymphatic function, was obtained through the FSL pipeline. The differences in these dices between groups were compared, and their associations with systemic inflammation and oxidative stress were analyzed.

RESULTS

MDD patients showed increased ChP volume (total: d = 0.316, p < 0.001; left: d = 0.317, p < 0.001; right: d = 0.268, p = 0.003) and decreased DTI-ALPS index (d = -0.144, p = 0.022), with a negative correlation between them (ρ = -0.135, p < 0.001). In MDD patients, lower DTI-ALPS index was correlated with higher LHR (ρ = -0.107, p = 0.025) and MHR (ρ = -0.126, p = 0.008). Larger right ChP volume was associated with higher MLR (ρ = 0.107, p = 0.009), SIRI (ρ = 0.086, p = 0.036), PIV (ρ = 0.086, p = 0.036), MHR (ρ = 0.136, p = 0.004), and PHR (ρ = 0.126, p = 0.008), while larger total ChP volume was correlated with higher MHR (ρ = 0.097, p = 0.042) and PHR (ρ = 0.114, p = 0.017).

CONCLUSION

MDD appeared to be accompanied by an increase in ChP volume and a decrease in glymphatic function, and these changes were related to systemic inflammation and oxidative stress.

Intranasal dantrolene nanoparticles inhibit lipopolysaccharide-induced depression and anxiety behavior in mice

This study investigates the therapeutic effectiveness of intranasal dantrolene nanoparticles pretreatment to inhibit lipopolysaccharide (LPS)-induced pathological inflammation and synapse destruction and depressive and anxiety behavior in mice. B6SJLF1/J adult mice were pretreated with intranasal dantrolene nanoparticles (dantrolene: 5mg/kg), daily, Monday to Friday, 5 days per week, for 4 weeks. Then, mice were treated with an intraperitoneal injection of LPS (5mg/kg) for one time. Behavioral tests for depression and anxiety were performed 24 hours after a one-time LPS injection. Biomarkers for pyroptosis-related inflammation cytokines (IL-1β and IL-18) in the blood and brain were measured using enzyme-linked immunosorbent assay (ELISA) and immunoblotting, respectively. The changes of primary proteins activation inflammatory pyroptosis (NLRP3: NLR family pyrin domain containing 3, Caspase-1, N-GSDMD: N terminal protein gasdermin D) and synapse proteins (PSD-95 and synpatin-1) in brains were measured using immunoblotting. Intranasal dantrolene nanoparticles robustly inhibited LPS-induced depression and anxiety behavior. Intranasal dantrolene nanoparticles significantly inhibited LPS-induced pathological elevation of IL-1β and IL-18 in the blood and brain and inhibited LPS-induced activation of pyroptosis. Intranasal dantrolene nanoparticles significantly ameliorated decrease of PSD-95 and synpatin-1 proteins in brains. Thus, intranasal dantrolene nanoparticles have demonstrated neuroprotection against inflammation-mediated depression and anxiety behaviors and should be studied further as a future effective drug treatment of major depression disorder or anxiety psychiatric disorder.

Impaired unfolded protein response, BDNF and synuclein markers in postmortem dorsolateral prefrontal cortex and caudate nucleus of patients with depression and Parkinson's disease

Major depressive disorder (MDD) is characterized by significant impairment in social, emotional, and cognitive functioning. Its precise pathophysiology remains poorly understood. Alterations in protein homeostasis and some misfolded proteins have been identified within the brains of patients diagnosed with neuropsychiatric disorders. In contrast to neurodegenerative processes such as Parkinson's disease (PD), where the accumulation of aggregated α-synuclein (α-Syn) protein is a primary cause of significant neuronal loss, altered proteostasis in MDD may result in loss-of-function effects by modifying synaptic neuroplasticity. Moreover, aberrant activation of endoplasmic reticulum (ER) pathways may intensify the pathological alterations due to altered proteostasis. In this study, dorsolateral prefrontal cortex (dlPFC) and caudate nucleus from MDD patients and non-psychiatric controls were used. Postmortem samples of same brain areas from PD patients (Braak 2-3 and 5-6) and controls were also included. Protein levels of ER and unfolded protein response (UPR), synucleins (α-, β- and γ-Syn), and brain-derived neurotrophic factor (BDNF) were measured by Western-Blot. Phospho-eIF2α/eIF2α ratio was increased in the dlPFC and caudate nucleus of MDD and PD patients compared to their respective controls. Brain area-dependent changes in BiP and GRP94 levels were also found. We further detected accumulation of immature BDNF precursors and opposite changes in α- and β-Syn levels in the dlPFC of MDD and PD patients compared to controls. Our findings suggest that alterations in proteostasis contribute to the pathophysiology of MDD, as previously described in PD. A deeper understanding of the pathways involved will identify other candidate proteins and new targets with therapeutic potential.

Genetic and molecular basis of abnormal BOLD signaling variability in patients with major depressive disorder after electroconvulsive therapy

Electroconvulsive therapy (ECT) is an effective and rapid neuromodulatory intervention for treatment-resistant major depressive disorders (MDD). However, the precise mechanisms underlying their efficacies remain unclear. Resting-state functional magnetic resonance imaging (fMRI) data were collected from 84 individuals with MDD and healthy controls before and after ECT, and coefficient of variation of the BOLD signal (CVBOLD) analysis was combined with region of interest (ROI) functional connectivity (FC) analysis. To assess the reliability of the antidepressant mechanism of ECT, we analyzed the changes in CVBOLD in a separate cohort consisting of 35 patients with MDD who underwent ECT. Moreover, transcriptomic and neurotransmitter receptor data were used to reveal the genetic and molecular bases of the changes in CVBOLD. Patients with MDD who underwent ECT demonstrated increased CVBOLD in the left angular cortex and left precuneus. Following ECT, an increase in FC between the left precuneus and right lingual lobes was associated with improvements in Hamilton Depression Rating Scale (HAMD) scores. validation analysis consistently demonstrated similar changes in CVBOLD in two independent cohorts of patients with MDD. Moreover, these changes in CVBOLD were closely associated with thyroid hormone synthesis, oxidative phosphorylation, endocytosis, and the insulin signaling pathway, and were significantly correlated with the receptor/transporter density of serotonin and dopamine. These findings suggest that ECT modulates abnormal functions in the left angular cortex and left precuneus, leading to widespread changes in functional connectivity and neuroplasticity, especially in the default mode network, and exerts an antidepressant effect.

Gut microbiota causes depressive phenotype by modulating glycerophospholipid and sphingolipid metabolism via the gut-brain axis

Emerging evidence suggests that changes in the gut microbiota (GM) are related to prenatal depression onset, but the underlying molecular mechanisms remain obscure. This study was conducted to explore how disordered GM is involved in the onset of prenatal depression through the microbiome-gut-brain (MGB) axis. We transplanted fecal microbiota from women with and without prenatal depression into germ-free mice. Fecal metagenomic sequencing and LC-MS untargeted metabolomics analysis were performed to identify the GM composition, function, and metabolites in mice. Lipid metabolomics analysis was then used to characterize the lipid metabolism of brain tissue in mice. We found that mice transplanted with fecal microbiota from women with prenatal depression exhibited depressive-like behaviors as well as characteristic disorders of the phylum Firmicutes. Weighted Gene Correlation Network Analysis identified three microbial and one metabolic module in the gut, alongside two lipid metabolic modules in the brain, as significantly related to all depressive-like behaviors. These modules were enriched for glycerophospholipid and sphingolipid metabolism. In addition, the GM of mice with depressive-like behaviors were enriched and deficient in relevant functions and enzymes in the glycerophospholipid (mainly phosphatidylethanolamine) and sphingolipid (mainly hexosyl-ceramide) metabolic pathways, respectively. Consistently, glycerophospholipid and sphingolipid metabolites in the brains of depressive-like mice were up- and down-regulated. Increased phosphatidylethanolamine and decreased hexosyl-ceramide were significantly related to differential genera in the gut. Collectively, our findings provide a novel microbial and metabolic framework for understanding the role of the MGB axis in prenatal depression, indicating that the GM may be involved in the onset of depressive phenotypes by modulating central glycerophospholipid and sphingolipid metabolic homeostasis.

Persister Intestinal Bacteria, Epigenetics and Major Depression

The microbiota-gut-brain axis has been proposed as a potential modulator of mood disorders such as major depression. Complex bidirectional biochemical activities in this axis have been posited to participate in adverse mood disorders. Environmental and genetic factors have dominated recent discussions on depression. The prescription of antibiotics, antidepressants, adverse negative DNA methylation reactions and a dysbiotic gut microbiome have been cited as causal for the development and progression of depression. While research continues to investigate the microbiome-gut-brain axis, this review will explore the state of persistence of gut bacteria that underpins bacterial dormancy, possibly due to adverse environmental conditions and/or pharmaceutical prescriptions. Bacterial dormancy persistence in the intestinal microbial cohort could affect the role of bacterial epigenomes and DNA methylations. DNA methylations are highly motif driven exerting significant control on bacterial phenotypes that can disrupt bacterial metabolism and neurotransmitter formation in the gut, outcomes that can support adverse mood dispositions.

From Stress to Synapse: The Neuronal Atrophy Pathway to Mood Dysregulation

Mood disorders, including major depressive disorder and bipolar disorder, are among the most prevalent mental health conditions globally, yet their underlying mechanisms remain incompletely understood. This review critically examines the neuronal atrophy hypothesis, which posits that chronic stress and associated neurobiological changes lead to structural and functional deficits in critical brain regions, contributing to mood disorder pathogenesis. Key mechanisms explored include dysregulation of neurotrophic factors such as brain-derived neurotrophic factor (BDNF), elevated glucocorticoids from stress responses, neuroinflammation mediated by cytokines, and mitochondrial dysfunction disrupting neuronal energy metabolism. These processes collectively impair synaptic plasticity, exacerbate structural atrophy, and perpetuate mood dysregulation. Emerging evidence from neuroimaging, genetic, and epigenetic studies underscores the complexity of these interactions and highlights the role of environmental factors such as early-life stress and urbanization. Furthermore, therapeutic strategies targeting neuroplasticity, including novel pharmacological agents, lifestyle interventions, and anti-inflammatory treatments, are discussed as promising avenues for improving patient outcomes. Advancing our understanding of the neuronal atrophy hypothesis could lead to more effective, sustainable interventions for managing mood disorders and mitigating their global health burden.

The Role and Mechanisms of Probiotic Supplementation on Depressive Symptoms: A Narrative Review

PURPOSE OF REVIEW

The microbiota-gut-brain-axis (MGBA) plays a role in the aetiology of mental disorders. Depression, a leading cause of disability worldwide, may be improved by probiotics. The aim of this narrative review is to investigate and synthesize the current evidence linking probiotic food supplementation with depressive symptomology.

RECENT FINDINGS

The gut and the brain communicate and interact via the MGBA through inflammation and the immune system, short chain fatty acid production, neuronal innervation and activation as well as endocrine and neurotransmitter modulation. Dysregulation of gut-brain pathways are caused by gut dysbiosis and implicated in the onset, persistence and exacerbation of depression related symptoms. Modulation of the gut microbiota via administration of probiotics has shown to reduce depressive symptom severity with Bifidobacterium and Lactobacillus strains being the most reported. Probiotics may produce greater benefits in mild depression rather than in chronic, treatment resistant depression. Probiotic supplementation is a promising and safe approach for the prevention of severe depressive disorders in high-risk individuals such as people with subthreshold depression. However, the mechanistic pathways of the MGBA require further investigation and additional human clinical trials are necessary to evaluate the role of probiotics on depression.

Agomelatine Alleviates Depressive-like Behaviors by Suppressing Hippocampal Oxidative Stress in the Chronic Social Defeat Stress Model

Major depressive disorder (MDD) is a common psychiatric disorder characterized by significant mood disturbances and cognitive impairments. Chronic stress, particularly social defeat stress, plays a crucial role in the etiology of depression, with oxidative stress being a pivotal factor in its pathophysiology. Consequently, identifying effective strategies to mitigate oxidative stress and prevent the progression of depression is of paramount importance. Agomelatine, an atypical antidepressant with melatonergic and serotonergic properties, has shown promise in treating MDD due to its unique mechanisms of action. In this study, we aimed to investigate whether agomelatine could ameliorate behavioral deficits in a chronic social defeat stress (CSDS) mouse model. CSDS mice were administered agomelatine (50 mg/kg, intraperitoneally) and exhibited significant reductions in both anxiety-like and depressive-like behaviors in behavioral tests. Further analysis revealed that agomelatine treatment effectively reduced oxidative damage in the hippocampus of CSDS mice. Additionally, agomelatine attenuated mitochondrial dysfunction and restored synaptic plasticity, as evidenced by an increased density of excitatory synapses and enhanced neuronal activity. These findings suggest that agomelatine may exert therapeutic effects by reducing oxidative stress, preserving mitochondrial function, and enhancing synaptic plasticity, providing new insights into its potential as a treatment for chronic social defeat stress-induced depression.

Electroacupuncture restores maternal separation-induced glutamatergic presynaptic deficits of the medial prefrontal cortex in adulthood

Maternal separation (MS) serves as a critical model of early life stress (ELS) that can lead to mood disorders, such as depression. Our previous studies suggest that MS may disrupt synaptic transmission in adulthood. While electroacupuncture (EA) has demonstrated antidepressant effects in several animal models of stress-induced depression, it remains unclear whether EA can reverse synaptic transmission deficits caused by ELS. In this study, we examined the effects of EA at Baihui (GV20) and Yintang (GV29) on both behavioural deficits and glutamatergic synaptic transmission in Sprague-Dawley rats subjected to MS. First, we showed that EA effectively alleviated anhedonia and despair-like behaviours. Furthermore, our data indicated that EA restored the decrease in presynaptic glutamate release, as evidenced by changes in the frequency of miniature excitatory postsynaptic currents (mEPSCs) and paired-pulse ratios (PPR). Microdialysis results also suggested that EA elevated extracellular glutamate levels. To explore the underlying mechanisms, we performed Western blot analyses on several proteins involved in glutamatergic synaptic transmission. Notably, we found that EA treatment increased the expression of vesicular glutamate transporters (VGLUT1 and VGLUT2) and vesicle-associated release proteins (SNAP25, Syntaxin-1A, and VAMP2) in the medial prefrontal cortex (mPFC) of MS rats. In contrast, EA did not significantly affect most postsynaptic glutamatergic receptors. These findings underscore the significant impact of EA on glutamatergic synaptic transmission, particularly in restoring presynaptic impairments induced by MS in adulthood.

Leveraging pleiotropic clustering to address high proportion correlated horizontal pleiotropy in Mendelian randomization studies

Mendelian randomization harnesses genetic variants as instrumental variables to infer causal relationships between exposures and outcomes. However, certain genetic variants can affect both the exposure and the outcome through a shared factor. This phenomenon, called correlated horizontal pleiotropy, may result in false-positive causal findings. Here, we propose a Pleiotropic Clustering framework for Mendelian randomization, PCMR. PCMR detects correlated horizontal pleiotropy and extends the zero modal pleiotropy assumption to enhance causal inference in trait pairs with correlated horizontal pleiotropic variants. Simulations show that PCMR can effectively detect correlated horizontal pleiotropy and avoid false positives in the presence of correlated horizontal pleiotropic variants, even when they constitute a high proportion of the variants connecting both traits (e.g., 30-40%). In datasets consisting of 48 exposure-common disease pairs, PCMR detects horizontal correlated pleiotropy in 7 out of the exposure-common disease pairs, and avoids detecting false positive causal links. Additionally, PCMR can facilitate the integration of biological information to exclude correlated horizontal pleiotropic variants, enhancing causal inference. We apply PCMR to study causal relationships between three common psychiatric disorders as examples.

Curvilinear association between cardiometabolic index and depressive symptoms in individuals aged 45 and older: a cross-sectional study of CHARLS

Objective

This research is aimed at investigating the association between the cardiometabolic index (CMI) and depressive symptoms in Chinese population of middle and older age, using data derived from the CHARLS study.

Methods

Using data from 7,800 participants in the 2011-2012 wave of the CHARLS cohort, this cross-sectional analysis concentrated on examining the association between CMI and depressive symptoms, assessed through CESD-10 scores. The study utilized multivariate logistic regression, multiple linear regression, and restricted cubic spline (RCS) models to investigate the link between CMI and depression, with subgroup analyses offering further insights. Sensitivity analyses included propensity score matching and data from 8,457 participants in the 2015-2016 CHARLS wave.

Results

In fully adjusted models, higher CMI was significantly associated with an elevated risk of depression, with participants having a CMI ≥ 0.594 showing a 162% higher risk compared to those with lower CMI. The RCS analysis identified a threshold at CMI = 0.594, where participants with CMI ≥ 0.594 had a 162% elevated possibility of depression in comparison to those with CMI < 0.594 [OR = 2.62, 95% CI: 2.36-2.91]. Sensitivity analyses, including propensity score matching and data from the 2015-2016 CHARLS wave, confirmed the robustness of the findings.

Conclusion

Our analysis demonstrates that elevated CMI levels are independently correlated with a heightened likelihood of experiencing depressive symptoms, highlighting the significance of metabolic interventions in mitigating depressive tendencies in middle-aged and older individuals.

Increased individual variability in functional connectivity of the default mode network and its genetic correlates in major depressive disorder

Major depressive disorder (MDD) is a highly heterogeneous psychiatric disorder characterized with considerable individual variability in clinical manifestations which may correspond to brain alterations including the default mode network (DMN). This study analyzed resting-state functional magnetic resonance imaging (rs-fMRI) data from 796 MDD patients and 823 healthy controls (HC) to investigate individual variability in functional connectivity (IVFC) between the DMN and 108 non-DMN regions. We aimed to identify MDD-related IVFC abnormalities and their clinical relevance, alongside exploring gene expression correlations. The results revealed similar spatial patterns of IVFC within the DMN in both groups, yet significantly increased IVFC values in MDD patients were observed in regions such as the ventromedial prefrontal cortex, anterior cingulate cortex, posterior cingulate cortex, fusiform gyrus, and occipital cortex. Notably, the mean IVFC in the DMN and fusiform gyrus was positively correlated with Hamilton Rating Scale for Depression (HAMD) scores in MDD patients. Gene expression analyses explained 47.0% of the variance in MDD-related IVFC alterations, with the most associated genes enriched in processes including membrane potential regulation, head development, synaptic transmission, and dopaminergic synapse. These findings highlight the clinical importance of IVFC variability in the DMN and suggest its potential role as a biomarker in MDD.

Neurobiological Relationships Between Neurodevelopmental Disorders and Mood Disorders

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), neurodevelopmental disorders (NDDs) are a group of conditions that arise early in development and are characterized by deficits in personal, social, academic, or occupational functioning. These disorders frequently co-occur and include conditions such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). Mood disorders (MDs), such as major depressive disorder and bipolar disorder, also pose significant global health challenges due to their high prevalence and substantial impact on quality of life. Emerging evidence highlights overlapping neurobiological mechanisms between NDDs and MDs, including shared genetic susceptibilities, neurotransmitter dysregulation (e.g., dopaminergic and serotonergic pathways), neuroinflammation, and hypothalamic-pituitary-adrenal (HPA) axis dysfunction. Environmental factors such as early-life adversity further exacerbate these vulnerabilities, contributing to the complexity of their clinical presentation and comorbidity. Functional neuroimaging studies reveal altered connectivity in brain regions critical for emotional regulation and executive function, such as the prefrontal cortex and amygdala, across these disorders. Despite these advances, integrative diagnostic frameworks and targeted therapeutic strategies remain underexplored, limiting effective intervention. This review synthesizes current knowledge on the shared neurobiological underpinnings of NDDs and MDs, emphasizing the need for multidisciplinary research, including genetic, pharmacological, and psychological approaches, for unified diagnosis and treatment. Addressing these intersections can improve clinical outcomes and enhance the quality of life for individuals affected by these disorders.

Rescue of CUMS-induced HPA axis hyperfunction and hypothalamic synaptic deficits by Citrus aurantium L. cv. Daidai essential oil via the cAMP/PKA/Grin2b pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine has historically used Citrus aurantium L. cv. Daidai to alleviate anxiety and improve mood. Essential oils are the primary active component of Citrus aurantium L. cv. Daidai, but little research has been conducted on the active substances and mechanisms of the antidepressant effect of Citrus aurantium L. cv. Daidai essential oil (CEO).

AIM OF THE STUDY

This research used network pharmacology, molecular docking, transcriptomics, and in vitro and in vivo experimental validation to assess the effectiveness and therapeutic mechanism of CEO.

MATERIALS AND METHODS

We used gas chromatography‒mass spectrometry (GC-MS) to identify and quantify CEO components and brain-penetrating chemicals. CEO was given to chronic and unpredictable mild stimulation (CUMS) mice for 4 weeks. Depression was assessed using sucrose preference, forced swimming, tail suspension, elevated plus-maze, and open field tests. Analyzing brain homogenates and serum biochemistry data simultaneously revealed neurotransmitter and hormone alterations. Tissue samples were collected for histological and protein analysis. Furthermore, transcriptome and network pharmacology were used to investigate the mechanism by which CEO alleviates depression, and in vitro glutamate (Glu)-induced PC12 cell injury assays were conducted to validate this new mechanism.

RESULTS

CEO inhalation altered neurotransmitter and hormone expression and improved CUMS-induced weight and depression-like behavior in mice. Compared with CUMS mice, CEO mice presented less pathological brain damage, as demonstrated by HE staining, immunohistochemistry, Golgi staining, transmission electron microscopy, and immunofluorescence staining. We discovered that 13 of the active chemicals in CEO act on 522 targets, 96 of which are linked to depression. PRKACA was identified as the core target by a modular analysis of the PPI network. Network pharmacology and transcriptomics revealed that CEO influences depression via the cAMP/PKA/Grin2b pathway and Glu synaptic modulation. In vivo studies indicated that CEO administration reduced PKA and Grin2b phosphorylation in CUMS mice, inhibited the cAMP/PKA/Grin2b pathway, protected against synaptic deficits, and restored HPA axis function. In vitro investigations revealed that the survival rate of PC12 cells treated with CEO increased, the apoptotic rate decreased, and the expression of LDH, Ca2+, and MDA decreased. Western blot and immunofluorescence staining indicated that CEO inhibits the cAMP/PKA/Grin2b pathway to regulate Glu-induced PC12 cells and that 8-Bromo-cAMP pretreatment reduces the protective effect of CEO.

CONCLUSIONS

The active chemicals in CEO can inhibit the cAMP/PKA/Grin2b pathway, reduce anxiety and depression, alleviate excitotoxicity caused by Glu synaptic overactivation, protect against hypothalamic synaptic deficits, and restore HPA axis function. This research could serve as a reference for the field of illness prevention and complementary therapies for depression.

Intranasal dantrolene nanoparticles inhibit lipopolysaccharide-induced helplessness and anxiety behavior in mice

This study investigates the therapeutic effectiveness of intranasal dantrolene nanoparticles pretreatment to inhibit lipopolysaccharide (LPS)-induced pathological inflammation and synapse destruction and depressive and anxiety behavior in mice. B6SJLF1/J adult mice were pretreated with intranasal dantrolene nanoparticles (dantrolene: 5mg/kg), daily, Monday to Friday, 5 days per week, for 4 weeks. Then, mice were treated with intraperitoneal injection of LPS (5mg/kg) for one time. Behavioral tests for depression and anxiety were performed 24 hours after a one-time LPS injection. Biomarkers for pyroptosis-related inflammation cytokines (IL-1β and IL-18) in blood and brains were measured using enzyme-linked immunosorbent assay (ELISA) and immunoblotting, respectively. The changes of primary proteins activation inflammatory pyroptosis (NLRP3: NLR family pyrin domain containing 3, Caspase-1, N-GSDMD: N terminal protein gasdermin D) and synapse proteins (PSD-95 and synpatin-1) in brains were measured using immunoblotting. Intranasal dantrolene nanoparticles robustly inhibited LPS-induced depression and anxiety behavior. Intranasal dantrolene nanoparticles significantly inhibited LPS-induced pathological elevation of IL-1β and IL-18 in the blood and brain and inhibited LPS induced activation of pyroptosis. Intranasal dantrolene nanoparticles significantly ameliorated decrease of PSD-95 and synpatin-1 proteins in brains. Thus, intranasal dantrolene nanoparticles has demonstrated neuroprotection against inflammation mediated depression and anxiety behaviors and should be studied furthermore as a future effective drug treatment of major depression disorder or anxiety psychiatric disorder.

Accelerated brain aging in patients with major depressive disorder and its neurogenetic basis: evidence from neurotransmitters and gene expression profiles

BACKGROUND

Numerous studies have explored the relationship between brain aging and major depressive disorder (MDD) and attempted to explain the phenomenon of faster brain aging in patients with MDD from multiple perspectives. However, a major challenge in this field is elucidating the ontological basis of these changes. Here, we aimed to explore the relationship between brain structural changes in MDD-related brain aging and neurotransmitter expression levels and transcriptomics.

METHODS

Imaging data from 670 Japanese participants (MDD: health controls = 233:437) and the support vector regression model were utilized to predict and compare brain age between MDD patients and healthy controls. A map of differences in cortical thickness was generated, furthermore, spatial correlation analysis with neurotransmitters and correlation analysis with gene expression were performed.

RESULTS

The degree of brain aging was found to be significantly higher in patients with MDD. Moreover, significant cortical thinning was observed in the left ventral area, and premotor eye field in patients with MDD. A significant correlation was observed between MDD-related cortical thinning and neurotransmitter receptors/transporters, including dopaminergic, serotonergic, and glutamatergic systems. Enriched Gene Ontology terms, including protein binding, plasma membrane, and protein processing, contribute to MDD-related cortical thinning.

CONCLUSIONS

The findings of this study provide further evidence that patients with MDD experience more severe brain aging, deepening our understanding of the underlying neural mechanisms and genetic basis of the brain changes involved. Additionally, these findings hold promise for the development of interventions aimed at preventing further deterioration in MDD-related brain aging, thus offering potential therapeutic avenues.

Association of optic neuritis with incident depressive disorder risk in a Korean nationwide cohort

Studies have highlighted complex bidirectional relationships between autoimmune diseases and depressive disorders. Given that early mental health interventions have substantial public health implications, this study investigated association between optic neuritis, an autoimmune inflammatory disorder of the optic nerve, and risk of developing depressive disorders. Utilizing extensive national health insurance data encompassing almost the entire Korean population, this cohort study included 11,745 patients with optic neuritis and 58,725 age- and sex- matched controls between 2010 and 2017. The diagnosis of optic neuritis was confirmed using ICD-10 code H46 and patient medical records. The association with depression risk identified by ICD-10 codes F32 and F33 was assessed using Cox proportional hazards regression models after adjusting for demographics, lifestyle variables, and other comorbidities. Newly diagnosed optic neuritis was associated with an increased risk of depression (hazard ratio = 1.349, 95% confidence interval: 1.277-1.426), independent of potential confounding factors. Subgroup analysis revealed a stronger association for individuals under 50 years, males, current smokers, and those without hypertension. This association suggests that autoimmune neuroinflammatory responses impact mental health differently across demographics. These findings underscore the importance of implementing routine depression screening and developing targeted early intervention strategies for patients with optic neuritis, particularly for those with a high-risk of depression.

New perspectives on galectin in major depressive disorder treatment

Galectins, a family of carbohydrate-binding proteins, regulate immune responses, neuroinflammation, and neurogenesis within the central nervous system (CNS). Among the 15 known galectins, galectins-1, -3, -4, -8, and -9 play significant roles in neuroinflammation and have been investigated in the context of CNS pathologies. This review synthesizes recent advancements in understanding galectins' involvement in the neurobiology of brain disorders, focusing on their interplay with signaling pathways underlying major depressive disorder (MDD). It explores their impact on neuroinflammation, neurogenesis, and brain signaling, highlighting the therapeutic potential of targeting galectins while addressing challenges in translating these findings into clinical practice. Comprehensive studies are essential to unravel the complex mechanisms of galectin-mediated pathways and unlock their full potential for managing neuropsychiatric conditions.