Dysregulation of mitochondrial dynamics, mitophagy and apoptosis in major depressive disorder: Does inflammation play a role?

AdipoRon exerts an antidepressant effect by inhibiting NLRP3 inflammasome activation in microglia via promoting mitophagy

Depression is a serious mental disorder that threatens patients' physical and mental health worldwide. The activation of the NLR family pyrin domain-containing 3 (NLRP3) inflammasome is essential for microglia-mediated neuroinflammation and neuronal damage in depression. Numerous pathophysiological factors, such as mitochondrial dysfunction and impaired mitophagy, have an essential role in activating the NLRP3 inflammasome. AdipoRon is a potent adiponectin receptor agonist; however, its antidepressant effects have not been thoroughly investigated. In this study, we found that AdipoRon ameliorated depression-like behavior and neuronal damage induced by chronic unpredictable mild stress (CUMS). Further research demonstrated that AdipoRon inhibited the activation of the NLRP3 inflammasome and protected hippocampal neurons from microglial cytotoxicity by promoting mitophagy, increasing the clearance of damaged mitochondria, and reducing mtROS accumulation. Importantly, inhibition of mitophagy attenuated the antidepressant and neuroprotective effects of AdipoRon. Overall, these findings indicate that AdipoRon alleviates depression by inhibiting NLRP3 inflammasome activation in microglia via improving mitophagy.

VPS13D affects epileptic seizures by regulating mitochondrial fission and autophagy in epileptic rats

Abnormal mitochondrial dynamics can lead to seizures, and improved mitochondrial dynamics can alleviate seizures. Vacuolar protein sorting 13D (VPS13D) is closely associated with regulating mitochondrial homeostasis and autophagy. However, further investigation is required to determine whether VPS13D affects seizures by influencing mitochondrial dynamics and autophagy. We aimed to investigate the influence of VPS13D on behavior in a rat model of acute epileptic seizures. Hence, we established an acute epileptic seizure rat model and employed the CRISPR/CAS9 technology to construct a lentivirus to silence the Vps13d gene. Furthermore, we used the HT22 mouse hippocampal neuron cell line to establish a stable strain with suppressed expression of Vps13d in vitro. Then, we performed quantitative proteomic and bioinformatics analyses to confirm the mechanism by which VPS13D influences mitochondrial dynamics and autophagy, both in vitro and in vivo using the experimental acute epileptic seizure model. We found that knockdown of Vps13d resulted in reduced seizure latency and increased seizure frequency in the experimental rats. Immunofluorescence staining and western blot analysis revealed a significant increase in mitochondrial dynamin-related protein 1 expression following Vps13d knockdown. Moreover, we observed a significant reduction in LC3II protein expression levels and the LC3II/LC3I ratio (indicators for autophagy) accompanied by a significant increase in P62 expression (an autophagy adaptor protein). The proteomic analysis confirmed the up-regulation of P62 protein expression. Therefore, we propose that VPS13D plays a role in modulating seizures by influencing mitochondrial dynamics and autophagy.

Parkin, a Parkinson's disease-associated protein, mediates the mitophagy that plays a vital role in the pathophysiology of major depressive disorder

Depression is a complex mood disorder with multifactorial etiology and is also the most frequent non-motor symptom of Parkinson's disease. Emerging research suggests a potential link between mitochondrial dysfunction and the pathophysiology of major depressive disorder. By synthesizing current knowledge and research findings, this review sheds light on the intricate relationship between Parkin, a protein classically associated with Parkinson's disease, and mitochondrial quality control mechanisms (e.g., mitophagy, mitochondrial biogenesis, and mitochondrial dynamic), specifically focusing on their relevance in the context of depression. Additionally, the present review discusses therapeutic strategies targeting Parkin-medicated mitophagy and calls for further research in this field. These findings suggest promise for the development of novel depression treatments through modulating Parkin-mediated mitophagy.

Mitochondrial dynamics and psychiatric disorders: The missing link

Elucidating the molecular mechanisms of psychopathology is crucial for optimized diagnosis and treatment. Accumulating data have underlined how mitochondrial bioenergetics affect major psychiatric disorders. However, how mitochondrial dynamics, a term addressing mitochondria quality control, including mitochondrial fission, fusion, biogenesis and mitophagy, is implicated in psychopathologies remains elusive. In this review, we summarize the existing literature on mitochondrial dynamics perturbations in psychiatric disorders/neuropsychiatric phenotypes. We include preclinical/clinical literature on mitochondrial dynamics recalibrations in anxiety, depression, post-traumatic stress disorder (PTSD), bipolar disorder and schizophrenia. We discuss alterations in mitochondrial network, morphology and shape, molecular markers of the mitochondrial dynamics machinery and mitochondrial DNA copy number (mtDNAcn) in animal models and human cohorts in brain and peripheral material. By looking for common altered mitochondrial dynamics patterns across diagnoses/phenotypes, we highlight mitophagy and biogenesis as regulators of anxiety and depression pathophysiology, respectively, as well as the fusion mediator dynamin-like 120 kDa protein (Opa1) as a molecular hub contributing to psychopathology. Finally, we comment on limitations and future directions in this novel neuropsychiatry field.

Crotonaldehyde paralyzes arteries by inducing impairment of ion channels, vascular histiocytic injury, overproduction of reactive oxygen species, mitochondrial damage, and autophagy

Humans are ubiquitously exposed to crotonaldehyde (CRA) endogenously and exogenously. Deeper knowledge of the pharmacological and toxicological characteristics and the mechanisms of CRA on vasculature is urgently needed for prevention of its harmfulness. The effects of acute and prolonged exposure to CRA were studied in rat isolated arteries and arterial smooth muscle cells (ASMCs). Instant exposure to CRA (1-300 μM) concentration-dependently declined the tension of pre-constricted arteries with an irreversible depression on the contractility. Prolonged exposure of rat coronary arteries (RCAs) to CRA concentration- and time-dependently depressed the arterial contractile responsiveness to various vasoconstrictors including depolarization, U46619, serotonin and Bay K8644 (an agonist of voltage-gated Ca2+ channels (VGCCs)). In fresh RCA ASMCs, CRA abated depolarization-induced elevation of intracellular Ca2+ ([Ca2+]i). Electrophysiological study revealed that acute exposure to CRA depressed the functions of Ca2+-activated Cl- channels (CaCCs), voltage-gated K+ (Kv) channels and inward rectifier K+ (Kir) channels in RCA ASMCs. Prolonged exposure of RCAs to CRA reduced the expressions of these ion channels in RCA ASMCs, disordered tissue frames, injured arterial cells, and increased autophagosomes in both ASMCs and endothelial cells. In rat aortic smooth muscle cells (A7r5), CRA exposure decreased the cell viability, elevated the intracellular levels of reactive oxygen species, reduced the mitochondrial membrane potential, and enhanced autophagy. Taken together, the present study for the first time portrays a clearer panoramic outline of the vascular effects and the mechanisms of CRA on arteries, demonstrates that CRA impairs arterial contractility, depresses VGCCs, CaCCs, Kv channels and Kir channels, reduces cell viability, and destroys the arterial histiocytes, and suggests that excessive oxidative stress, mitochondrial dysfunction and autophagy underlie these vascular damages. These findings are significant for the comprehensive evaluation of the vicious effects of CRA on arteries and suggest potential preventive strategies.

Role of mitochondria-associated membranes in the hippocampus in the pathogenesis of depression

BACKGROUND

Pathological changes, such as microglia activation in the hippocampus frequently occur in individuals with animal models of depression; however, they may share a common cellular mechanism, such as endoplasmic reticulum (ER) stress and mitochondrial dysfunction. Mitochondria associated membranes (MAMs) are communication platforms between ER and mitochondria. This study aimed to investigate the role of intracellular stress responses, especially structural and functional changes of MAMs in depression.

METHODS

We used chronic social defeat stress (CSDS) to mimic depression in C57 mice to investigate the pathophysiological changes in the hippocampus associated with depression and assess the antidepressant effect of electroacupuncture (EA). Molecular, histological, and electron microscopic techniques were utilized to study intracellular stress responses, including the ER stress pathway reaction, mitochondrial damage, and structural and functional changes in MAMs in the hippocampus after CSDS. Proteomics technology was employed to explore protein-level changes in MAMs caused by CSDS.

RESULTS

CSDS caused mitochondrial dysfunction, ER stress, closer contact between ER and mitochondria, and enrichment of functional protein clusters at MAMs in hippocampus along with depressive-like behaviors. Also, EA showed beneficial effects on intracellular stress responses and depressive-like behaviors in CSDS mice.

LIMITATION

The cellular specificity of MAMs related protein changes in CSDS mice was not explored.

CONCLUSIONS

In the hippocampus, ER stress and mitochondrial damage occur, along with enriched mitochondria-ER interactions and MAM-related protein enrichment, which may contribute to depression's pathophysiology. EA may improve depression by regulating intracellular stress responses.

Identification of mitophagy-related genes and analysis of immune infiltration in the astrocytes based on machine learning in the pathogenesis of major depressive disorder

BACKGROUNDS

Major depressive disorder (MDD) is a pervasive mental and mood disorder with complicated and heterogeneous etiology. Mitophagy, a selective autophagy of cells, specifically eliminates dysfunctional mitochondria. The mitochondria dysfunction in the astrocytes is regarded as a critical pathogenetic mechanism of MDD. However, studies on the mitophagy of astrocytes in MDD are scarce. To explore the impact of mitophagy on the astrocytes, we used bioinformatic methods to analyze the correlation between astrocyte-related genes and mitophagy-related genes in MDD.

METHODS

The microarray dataset of MDD was downloaded from the Gene Expression Omnibus database and identified astrocyte- and mitophagy-related differentially expressed genes (AMRDEGs). We used three machine learning algorithms to identify hub AMRDEGs and constructed a diagnostic prediction model. Also, we analyzed transcription factor-gene and gene-microRNA interaction networks, and the immune infiltration in MDD and healthy controls. Besides, we performed consensus clustering analysis, immune infiltration analysis, and gene set variation analysis of MDD samples.

RESULTS

The present research identified 3 hub AMRDEGs (GRN, NDUFAF4, and SNCA), and a good diagnostic model with potential clinical applications was constructed and validated. Besides, we identified 6 transcription factors and 14 microRNAs. The immune infiltration analysis showed that MDD was closely related to immune cells. Gene set variant analysis showed that MDD was related to immune and mitochondrial metabolism and inflammatory signaling pathways.

CONCLUSIONS

We identified 3 hub AMRDEGs, new biomarkers for treating and diagnosing MDD and associated with immuno-inflammation. Our research provides new insights into the early diagnosis and treatment of MDD.

Transcriptomic profiles in major depressive disorder: the role of immunometabolic and cell-cycle-related pathways in depression with different levels of inflammation

Transcriptomic profiles are important indicators for molecular mechanisms and pathways involved in major depressive disorder (MDD) and its different phenotypes, such as immunometabolic depression. We performed whole-transcriptome and pathway analyses on 139 individuals from the observational, case-control, BIOmarkers in DEPression (BIODEP) study, 105 with MDD and 34 controls. We divided MDD participants based on levels of inflammation, as measured by serum high-sensitivity C-reactive protein (CRP), in n = 39 'not inflamed' (CRP < 1 mg/L), n = 31 with 'elevated CRP' (1-3 mg/L), and n = 35 with 'low-grade inflammation' (>3 mg/L). We performed whole-blood RNA sequencing using Illumina NextSeq 550 and statistical analyses with the Deseq2 package for R statistics (RUV-corrected) and subsequent pathway analyses with Ingenuity Pathway Analysis. Immunometabolic pathways were activated in individuals with CRP > 1 mg/L, although surprisingly the CRP 1-3 group showed stronger immune activation than the CRP > 3 group. The main pathways identified in the comparison between CRP < 1 group and controls were cell-cycle-related, which may be protective against immunometabolic abnormalities in this 'non-inflamed' depressed group. We further divided MDD participants based on exposure and response to antidepressants (n = 47 non-responders, n = 37 responders, and n = 22 unmedicated), and identified specific immunomodulatory and neuroprotective pathways in responders (especially vs. non-responders), which could be relevant to treatment response. In further subgroup analyses, we found that the specific transcriptional profile of responders is independent of CRP levels, and that the inhibition of cell-cycle-related pathways in MDD with CRP < 1 mg/L is present only in those who are currently depressed, and not in the responders. The present study demonstrates immunometabolic and cell-cycle-related transcriptomic pathways associated with MDD and different (CRP-based and treatment-based) MDD phenotypes, while shedding light on potential molecular mechanisms that could prevent or facilitate an individual's trajectory toward immunometabolic depression and/or treatment-non-responsive depression. The recognition and integration of these mechanisms will facilitate a precision-medicine approach in MDD.

Revealing genetic causality between blood-based biomarkers and major depression in east Asian ancestry

Introduction

Major Depression (MD) is a common mental disorder. In East Asian ancestry, the association, causality, and shared genetic basis between blood-based biomarkers and MD remain unclear.

Methods

We investigated the relationships between blood-based biomarkers and MD through a cross-sectional study and Mendelian randomization (MR) analysis. Cross-trait analysis and enrichment analyses were used to highlight the shared genetic determinants and biological pathways. We conducted summary data-based MR to identify shared genes, which were then validated using a transcriptome dataset from drug-naïve patients with MD.

Results

In the cross-sectional study, C-Reactive Protein showed the significantly positive correlation with depressive symptoms, while hematocrit, hemoglobin, and uric acid exhibited significantly negative correlations. In MR analysis, basophil count (BASO) and low-density lipoprotein cholesterol (LDLc) had a significant causal effect on MD. The enrichment analysis indicated a significant role of inflammatory cytokines and oxidative stress. The shared genes MFN2, FAM55C, GCC2, and SCAPER were validated, with MFN2 identified as a pleiotropic gene involved in MD, BASO, and LDLc.

Discussion

This study highlighted that BASO and LDLc have a causal effect on MD in East Asian ancestry. The pathological mechanisms of MD are related not only to inflammatory cytokines and oxidative stress but also to down regulation of MFN2 expression and mitochondrial dysfunction.

Molecular mechanism and potential role of mitophagy in acute pancreatitis

Acute pancreatitis (AP) is a multifaceted inflammatory disorder stemming from the aberrant activation of trypsin within the pancreas. Despite the contribution of various factors to the pathogenesis of AP, such as trypsin activation, dysregulated increases in cytosolic Ca2+ levels, inflammatory cascade activation, and mitochondrial dysfunction, the precise molecular mechanisms underlying the disease are still not fully understood. Mitophagy, a cellular process that preserves mitochondrial homeostasis under stress, has emerged as a pivotal player in the context of AP. Research suggests that augmenting mitophagy can mitigate pancreatic injury by clearing away malfunctioning mitochondria. Elucidating the role of mitophagy in AP may pave the way for novel therapeutic strategies. This review article aims to synthesize the current research findings on mitophagy in AP and underscore its significance in the clinical management of the disorder.

The Interplay of Mitochondrial Dysfunction in Oral Diseases: Recent Updates in Pathogenesis and Therapeutic Implications

Mitochondrial dysfunction is linked to various systemic and localized diseases, including oral diseases like periodontitis, oral cancer, and temporomandibular joint disorders. This paper explores the intricate mechanisms underlying mitochondrial dysfunction in oral pathologies, encompassing oxidative stress, inflammation, and impaired energy metabolism. Furthermore, it elucidates the bidirectional relationship between mitochondrial dysfunction and oral diseases, wherein the compromised mitochondrial function exacerbates disease progression, while oral pathologies, in turn, exacerbate mitochondrial dysfunction. Understanding these intricate interactions offers insights into novel therapeutic strategies targeting mitochondrial function for managing oral diseases. This paper pertains to the mechanisms underlying mitochondrial dysfunction, its implications in various oral pathological and inflammatory conditions, and emerging versatile treatment approaches. It reviews current therapeutic strategies to mitigate mitochondrial dysfunction, including antioxidants, mitochondrial-targeted agents, and metabolic modulators.

Increased expression of ER stress, inflammasome activation, and mitochondrial biogenesis-related genes in peripheral blood mononuclear cells in major depressive disorder

A subset of major depressive disorder (MDD) is characterized by immune system dysfunction, but the intracellular origin of these immune changes remains unclear. Here we tested the hypothesis that abnormalities in endoplasmic reticulum (ER) stress, inflammasome activity and mitochondrial biogenesis contribute to the development of systemic inflammation in MDD. RT-qPCR was used to measure mRNA expression of key organellar genes from peripheral blood mononuclear cells (PBMCs) isolated from 186 MDD and 67 healthy control (HC) subjects. The comparative CT (2-ΔΔCT) method was applied to quantify mRNA expression using GAPDH as the reference gene. After controlling for age, sex, BMI, and medication status using linear regression models, expression of the inflammasome (NLRC4 and NLRP3) and the ER stress (XBP1u, XBP1s, and ATF4) genes was found to be significantly increased in the MDD versus the HC group. Sensitivity analyses excluding covariates yielded similar results. After excluding outliers, expression of the inflammasome genes was no longer statistically significant but expression of the ER stress genes (XBP1u, XBP1s, and ATF4) remained significant and the mitochondrial biogenesis gene, MFN2, was significantly increased in the MDD group. NLRC4 and MFN2 were positively correlated with serum C-reactive protein concentrations, while ASC trended significant. The altered expression of inflammasome activation, ER stress, and mitochondrial biogenesis pathway components suggest that dysfunction of these organelles may play a role in the pathogenesis of MDD.

Mitophagy and cGAS-STING crosstalk in neuroinflammation

Mitophagy, essential for mitochondrial health, selectively degrades damaged mitochondria. It is intricately linked to the cGAS-STING pathway, which is crucial for innate immunity. This pathway responds to mitochondrial DNA and is associated with cellular stress response. Our review explores the molecular details and regulatory mechanisms of mitophagy and the cGAS-STING pathway. We critically evaluate the literature demonstrating how dysfunctional mitophagy leads to neuroinflammatory conditions, primarily through the accumulation of damaged mitochondria, which activates the cGAS-STING pathway. This activation prompts the production of pro-inflammatory cytokines, exacerbating neuroinflammation. This review emphasizes the interaction between mitophagy and the cGAS-STING pathways. Effective mitophagy may suppress the cGAS-STING pathway, offering protection against neuroinflammation. Conversely, impaired mitophagy may activate the cGAS-STING pathway, leading to chronic neuroinflammation. Additionally, we explored how this interaction influences neurodegenerative disorders, suggesting a common mechanism underlying these diseases. In conclusion, there is a need for additional targeted research to unravel the complexities of mitophagy-cGAS-STING interactions and their role in neurodegeneration. This review highlights potential therapies targeting these pathways, potentially leading to new treatments for neuroinflammatory and neurodegenerative conditions. This synthesis enhances our understanding of the cellular and molecular foundations of neuroinflammation and opens new therapeutic avenues for neurodegenerative disease research.

CRHR1 antagonist alleviated depression-like behavior by downregulating p62 in a rat model of post-stroke depression

Post-stroke depression (PSD) is a complication of cerebrovascular disease, which can increase mortality after stroke. CRH is one of the main signaling peptides released after activation of the hypothalamic-pituitary-adrenal (HPA) axis in response to stress. It affects synaptic plasticity by regulating inflammation, oxidative stress and autophagy in the central nervous system. And the loss of spines exacerbates depression-like behavior. Therefore, synaptic deficits induced by CRH may be related to post-stroke depression. However, the underlying mechanism remains unclear. The Keap1-Nrf2 complex is one of the core components of the antioxidant response. As an autophagy associated protein, p62 participates in the Keap1-NrF2 pathway through its Keap1 interaction domain. Oxidative stress is involved in the feedback regulation between Keap1-Nrf2 pathway and p62.However, whether the relationship between CRH and the Keap1-Nrf2-p62 pathway is involved in PSD remains unknown. This study found that serum levels of CRH in 22 patients with PSD were higher than those in healthy subjects. We used MCAO combined with CUMS single-cage SD rats to establish an animal model of PSD. Animal experiments showed that CRHR1 antagonist prevented synaptic loss in the hippocampus of PSD rats and alleviated depression-like behavior. CRH induced p62 accumulation in the prefrontal cortex of PSD rats through CRHR1. CRHR1 antagonist inhibited Keap1-Nrf2-p62 pathway by attenuating oxidative stress. In addition, we found that abnormal accumulation of p62 induces PSD. It alleviates depression-like behavior by inhibiting the expression of p62 and promoting the clearance of p62 in PSD rats. These findings can help explore the pathogenesis of PSD and design targeted treatments for PSD.

Epigallocatechin gallate attenuated high glucose-induced pancreatic beta cell dysfunction by modulating DRP1-mediated mitochondrial apoptosis pathways

Long-term exposure to hyperglycemic conditions leads to β-cell dysfunction, particularly mitochondrial dysfunction, and inflammatory and oxidative stress responses, which are considered the primary causes of β-cell death and the hallmarks of diabetes. Plant-active ingredients may play a key role in glycemic control. Epigallocatechin gallate (EGCG) is a characteristic catechin derived from tea that possesses anti-diabetic properties. Nonetheless, its underlying mechanisms remain elusive. Herein, the protective role of EGCG on high glucose (33 mM)-induced pancreatic beta cell dysfunction and its possible molecular mechanisms were investigated. Briefly, MIN6 cells were treated with glucose and EGCG (10 µM, 20 µM, and 40 µM) for 48 h. Our results revealed that EGCG dose-dependently restored mitochondrial membrane potential and concomitantly alleviated cell apoptosis. Mechanistically, the expression level of apoptotic protein BAX and Dynamic related protein 1 (DRP1) was significantly downregulated following EGCG treatment, whereas that of the anti-apoptotic protein BCL-2 was significantly upregulated. Taken together, EGCG alleviated high glucose-induced pancreatic beta cell dysfunction by targeting the DRP1-related mitochondrial apoptosis pathway and thus can serve as a nutritional intervention for the preservation of beta cell dysfunction in patients with type 2 diabetes mellitus.

BGP-15 alleviates LPS-induced depression-like behavior by promoting mitophagy

The high prevalence of major depressive disorder (MDD) frequently imposes severe constraints on psychosocial functioning and detrimentally impacts overall well-being. Despite the growing interest in the hypothesis of mitochondrial dysfunction, the precise mechanistic underpinnings and therapeutic strategies remain unclear and require further investigation. In this study, an MDD model was established in mice using lipopolysaccharide (LPS). Our research findings demonstrated that LPS exposure induced depressive-like behaviors and disrupted mitophagy by diminishing the mitochondrial levels of PINK1/Parkin in the brains of mice. Furthermore, LPS exposure evoked the activation of the NLRP3 inflammasome, accompanied by a notable elevation in the concentrations of pro-inflammatory factors (TNF-α, IL-1β, and IL-6). Additionally, neuronal apoptosis was stimulated through the JNK/p38 pathway. The administration of BGP-15 effectively nullified the impact of LPS, corresponding to the amelioration of depressive-like phenotypes and restoration of mitophagy, prevention of neuronal injury and inflammation, and suppression of reactive oxygen species (ROS)-mediated NLRP3 inflammasome activation. Furthermore, we elucidated the involvement of mitophagy in BGP-15-attenuated depressive-like behaviors using the inhibitors targeting autophagy (3-MA) and mitophagy (Mdivi-1). Notably, these inhibitors notably counteracted the antidepressant and anti-inflammatory effects exerted by BGP-15. Based on the research findings, it can be inferred that the antidepressant properties of BGP-15 in LPS-induced depressive-like behaviors could potentially be attributed to the involvement of the mitophagy pathway. These findings offer a potential novel therapeutic strategy for managing MDD.

Pharmacological mechanism of natural antidepressants: The role of mitochondrial quality control

BACKGROUND

Depression is a mental illness characterized by persistent sadness and a reduced capacity for pleasure. In clinical practice, SSRIs and other medications are commonly used for therapy, despite their various side effects. Natural products present distinct advantages, including synergistic interactions among multiple components and targeting multiple pathways, suggesting their tremendous potential in depression treatment. Imbalance in mitochondrial quality control (MQC) plays a significant role in the pathology of depression, emphasizing the importance of regulating MQC as a potential intervention strategy in addressing the onset and progression of depression. However, the role and mechanism through which natural products regulate MQC in depression treatments still need to be comprehensively elucidated, particularly in clinical and preclinical settings.

PURPOSE

This review was aimed to summarize the findings of recent studies and outline the pharmacological mechanisms by which natural products modulate MQC to exert antidepressant effects. Additionally, it evaluated current research limitations and proposed new strategies for future preclinical and clinical applications in the depression domain.

METHODS

To study the main pharmacological mechanisms underlying the regulation of MQC by natural products in the treatment of depression, we conducted a thorough search across databases such as PubMed, Web of Science, and ScienceDirect databases to classify and summarize the relationship between MQC and depression, as well as the regulatory mechanisms of natural products.

RESULTS

Numerous studies have shown that irregularities in the MQC system play an important role in the pathology of depression, and the regulation of the MQC system is involved in antidepressant treatments. Natural products mainly regulate the MQC system to induce antidepressant effects by alleviating oxidative stress, balancing ATP levels, promoting mitophagy, maintaining calcium homeostasis, optimizing mitochondrial dynamics, regulating mitochondrial membrane potential, and enhancing mitochondrial biogenesis.

CONCLUSIONS

We comprehensively summarized the regulation of natural products on the MQC system in antidepressants, providing a unique perspective for the application of natural products within antidepressant therapy. However, extensive efforts are imperative in clinical and preclinical investigations to delve deeper into the mechanisms underlying how antidepressant medications impact MQC, which is crucial for the development of effective antidepressant treatments.

PGC-1α in the hippocampus mediates depressive-like and stress-coping behaviours and regulates excitatory synapses in the dentate gyrus in mice

Decreased hippocampal synaptic plasticity is an important pathological change in stress-related mood disorders, including major depressive disorder. However, the underlying mechanism is unclear. PGC-1α, a transcriptional coactivator, is a key factor in synaptic plasticity. We investigated the relationships between changes in hippocampal PGC-1α expression and depressive-like and stress-coping behaviours, and whether they are related to hippocampal synapses. Adeno-associated virus was used to alter hippocampal PGC-1α expression in male C57BL/6 mice. The sucrose preference test and forced swimming test were used to assess their depressive-like and stress-coping behaviours, respectively. Immunohistochemistry and stereology were used to calculate the total number of excitatory synapses in each hippocampal subregion (the cornu ammonis (CA) 1, CA3, and dentate gyrus). Immunofluorescence was used to visualize the changes in dendritic structure. Western blotting was used to detect the expression of hippocampal PGC-1α and mitochondrial-associated proteins, such as UCP2, NRF1 and mtTFAs. Our results showed that mice with downregulated PGC-1α expression in the hippocampus exhibited depressive-like and passive stress-coping behaviours, while mice with upregulated PGC-1α in the hippocampus exhibited increased stress-coping behaviours. Moreover, the downregulation of hippocampal PGC-1α expression resulted in a decrease in the number of excitatory synapses in the DG and in the protein expression of UCP2 in the hippocampus. Alternatively, upregulation of hippocampal PGC-1α yielded the opposite results. This suggests that hippocampal PGC-1α is involved in regulating depressive-like and stress-coping behaviours and modulating the number of excitatory synapses in the DG. This provides new insight for the development of antidepressants.

Mitochondrial dynamics dysfunction: Unraveling the hidden link to depression

Depression is a common mental disorder and its pathogenesis is not fully understood. However, more and more evidence shows that mitochondrial dynamics dysfunction may play an important role in the occurrence and development of depression. Mitochondria are the centre of energy production in cells, and are also involved in important processes such as apoptosis and oxidative stress. Studies have found that there are abnormalities in mitochondrial function in patients with depression, including mitochondrial morphological changes, mitochondrial dynamics disorders, mitochondrial DNA damage, and impaired mitochondrial respiratory chain function. These abnormalities may cause excessive free radicals and oxidative stress in mitochondria, which further damage cells and affect the balance of neurotransmitters, causing or aggravating depressive symptoms. Studies have shown that mitochondrial dynamics dysfunction may participate in the occurrence and development of depression by affecting neuroplasticity, inflammation and neurotransmitters. This article reviews the effects of mitochondrial dynamics dysfunction on the pathogenesis of depression and its potential molecular pathway. The restorers for the treatment of depression by regulating the function of mitochondrial dynamics were summarized and the possibility of using mitochondrial dynamics as a biomarker of depression was discussed.

Mutational landscape of risk variants in comorbid depression and obesity: a next-generation sequencing approach

Major depression (MD) and obesity are complex genetic disorders that are frequently comorbid. However, the study of both diseases concurrently remains poorly addressed and therefore the underlying genetic mechanisms involved in this comorbidity remain largely unknown. Here we examine the contribution of common and rare variants to this comorbidity through a next-generation sequencing (NGS) approach. Specific genomic regions of interest in MD and obesity were sequenced in a group of 654 individuals from the PISMA-ep epidemiological study. We obtained variants across the entire frequency spectrum and assessed their association with comorbid MD and obesity, both at variant and gene levels. We identified 55 independent common variants and a burden of rare variants in 4 genes (PARK2, FGF21, HIST1H3D and RSRC1) associated with the comorbid phenotype. Follow-up analyses revealed significantly enriched gene-sets associated with biological processes and pathways involved in metabolic dysregulation, hormone signaling and cell cycle regulation. Our results suggest that, while risk variants specific to the comorbid phenotype have been identified, the genes functionally impacted by the risk variants share cell biological processes and signaling pathways with MD and obesity phenotypes separately. To the best of our knowledge, this is the first study involving a targeted sequencing approach toward the study of the comorbid MD and obesity. The framework presented here allowed a deep characterization of the genetics of the co-occurring MD and obesity, revealing insights into the mutational and functional profile that underlies this comorbidity and contributing to a better understanding of the relationship between these two disabling disorders.

Repurposing Ketamine in the Therapy of Depression and Depression-Related Disorders: Recent Advances and Future Potential

Depression represents a prevalent and enduring mental disorder of significant concern within the clinical domain. Extensive research indicates that depression is very complex, with many interconnected pathways involved. Most research related to depression focuses on monoamines, neurotrophic factors, the hypothalamic-pituitary-adrenal axis, tryptophan metabolism, energy metabolism, mitochondrial function, the gut-brain axis, glial cell-mediated inflammation, myelination, homeostasis, and brain neural networks. However, recently, Ketamine, an ionotropic N-methyl-D-aspartate (NMDA) receptor antagonist, has been discovered to have rapid antidepressant effects in patients, leading to novel and successful treatment approaches for mood disorders. This review aims to summarize the latest findings and insights into various signaling pathways and systems observed in depression patients and animal models, providing a more comprehensive view of the neurobiology of anxious-depressive-like behavior. Specifically, it highlights the key mechanisms of ketamine as a rapid-acting antidepressant, aiming to enhance the treatment of neuropsychiatric disorders. Moreover, we discuss the potential of ketamine as a prophylactic or therapeutic intervention for stress-related psychiatric disorders.

Assessing the joint effects of mitochondrial genes and physical activity on the psychiatric phenotype of subjective well-being based on the UK Biobank data

Subjective well-being (SWB) is an important measure for mental health status. Previous research has shown that physical activity can affect an individual's well-being, yet the underlying molecular mechanism remains to be clarified. In this study, we aim to evaluate the potential interactions between mitochondrial genes and physical activity (PA) as well as their combined effects on individual well-being. SWB phenotype data in UK Biobank were enrolled for this study including nine aspects such as work/job satisfaction, health satisfaction, family relationship satisfaction, friendships satisfaction, financial situation satisfaction, ever depressed for a whole week, general happiness, general happiness with own health and belief that own life is meaningful. We made analysis for each aspects separately. Firstly, mitochondria-wide association studies (MiWAS) was conducted to assess the association of mitochondrial Single Nucleotide Polymorphisms SNP with each aspect of SWB. Then an interaction analysis of mitochondrial DNA (mtDNA) mutation and PA was performed to evaluate their joint effect on SWB status. Meanwhile, these two analysis were made for female and male group separately as well as the total samples, all under the control of possible confounding factors including gender, age, Townsend Deprivation Index (TDI), education, alcohol consumption, smoking habits, and 10 principal components. MiWAS analysis identified 45 mtSNPs associated with 9 phenotypes of SWB. For example, m.15218A > G on MT-CYB in the health satisfaction phenotype of the total subjects. Gender-specific analyses found 30 mtSNPs in females and 58 in males, involving 13 mtGenes. In mtDNA-PA interaction analysis, we also identified 10 significant mtDNA-PA interaction sets for SWB. For instance, m.13020 T > C (MT-ND5) was associated with the SWB financial situation satisfaction phenotype in all subjects (P = 0.00577). In addition, MiWAS analysis identified 12 mtGene variants associated with SWB, as MT-ND1 and MT-ND2. However, in mtDNA-PA interactions we detected 7 mtDNA affecting psychiatric disorders occurring, as in the friendships satisfaction phenotype (m.3394 T > C on MT-ND1). Our study results suggest an implication of the interaction between mitochondrial function and physical activity in the risk of psychiatric disorder development.

Targeting autophagy to counteract neuroinflammation: A novel antidepressant strategy

Depression is a common disease that affects physical and mental health and imposes a considerable burden on afflicted individuals and their families worldwide. Depression is associated with a high rate of disability and suicide. It causes a severe decline in productivity and quality of life. Unfortunately, the pathophysiological mechanisms underlying depression have not been fully elucidated, and the risk of its treatment is still presented. Studies have shown that the expression of autophagic markers in the brain and peripheral inflammatory mediators are dysregulated in depression. Autophagy-related genes regulate the level of autophagy and change the inflammatory response in depression. Depression is related to several aspects of immunity. The regulation of the immune system and inflammation by autophagy may lead to the development or deterioration of mental disorders. This review highlights the role of autophagy and neuroinflammation in the pathophysiology of depression, sumaries the autophagy-targeting small moleculars, and discusses a novel therapeutic strategy based on anti-inflammatory mechanisms that target autophagy to treat the disease.

Brain-Region-Specific Genes Form the Major Pathways Featuring Their Basic Functional Role: Their Implication in Animal Chronic Stress Model

The analysis of RNA-Sec data from murine bulk tissue samples taken from five brain regions associated with behavior and stress response was conducted. The focus was on the most contrasting brain region-specific genes (BRSG) sets in terms of their expression rates. These BRSGs are identified as genes with a distinct outlying (high) expression rate in a specific region compared to others used in the study. The analysis suggested that BRSG sets form non-randomly connected compact gene networks, which correspond to the major neuron-mediated functional processes or pathways in each brain region. The number of BRSGs and the connection rate were found to depend on the heterogeneity and coordinated firing rate of neuron types in each brain region. The most connected pathways, along with the highest BRSG number, were observed in the Striatum, referred to as Medium Spiny Neurons (MSNs), which make up 95% of neurons and exhibit synchronous firing upon dopamine influx. However, the Ventral Tegmental Area/Medial Raphe Nucleus (VTA/MRN) regions, although primarily composed of monoaminergic neurons, do not fire synchronously, leading to a smaller BRSG number. The Hippocampus (HPC) region, on the other hand, displays significant neuronal heterogeneity, with glutamatergic neurons being the most numerous and synchronized. Interestingly, the two monoaminergic regions involved in the study displayed a common BRSG subnetwork architecture, emphasizing their proximity in terms of axonal throughput specifics and high-energy metabolism rates. This finding suggests the concerted evolution of monoaminergic neurons, leading to unique adaptations at the genic repertoire scale. With BRSG sets, we were able to highlight the contrasting features of the three groups: control, depressive, and aggressive mice in the animal chronic stress model. Specifically, we observed a decrease in serotonergic turnover in both the depressed and aggressive groups, while dopaminergic emission was high in both groups. There was also a notable absence of dopaminoceptive receptors on the postsynaptic membranes in the striatum in the depressed group. Additionally, we confirmed that neurogenesis BRSGs are specific to HPC, with the aggressive group showing attenuated neurogenesis rates compared to the control/depressive groups. We also confirmed that immune-competent cells like microglia and astrocytes play a crucial role in depressed phenotypes, including mitophagy-related gene Prkcd. Based on this analysis, we propose the use of BRSG sets as a suitable framework for evaluating case-control group-wise assessments of specific brain region gene pathway responses.

Aqueous Extract of Leaves and Flowers of Acmella caulirhiza Reduces the Proliferation of Cancer Cells by Underexpressing Some Genes and Activating Caspase-3

The increasing prevalence of cancers and the multiple side effects of cancer treatments have led researchers to constantly search for plants containing bioactive compounds with cell death properties. This work aimed at evaluating the antiproliferative effect of an Acmella caulirhiza extract. After evaluation of the in vitro antioxidant potential of the three extracts of Acmella caulirhiza (aqueous (AE-Ac), hydroethanolic (HEE-Ac), and ethanolic (EE-Ac)) through the scavenging of DPPH● and NO● radicals, the extract with the best antioxidant activity was selected for bioactive compound assessment and antiproliferative tests. Subsequently, the cytotoxic activity was evaluated on the viability of breast (MCF-7), brain (CT2A, SB-28, and GL-261), colon (MC-38), and skin (YUMM 1.7 and B16-F1) cancer lines using the MTT method. Then, the line where the extract was the most active was selected to evaluate the expression of certain genes involved in cancerogenesis by RT-PCR and the expression of cleaved caspase-3 involved in cell death mechanism by western blot. The AE-Ac showed the best scavenging activity with IC50s of 0.52 and 0.02 for DPPH● and NO●, respectively. This AE-Ac was found to contain alkaloids, flavonoids, and tannins and was more active on YUMM 1.7 cells (IC50 = 149.42 and 31.99 μg/mL for 24 and 48 h, respectively). Results also showed that AE-Ac downregulated the expression of inflammation (IL-1b (p = 0.017) and IL-6 (p = 0.028)), growth factors (PDGF (p = 0.039), IGF (p = 0.034), E2F1(p = 0.038), and E2F2(p = 0.016)), and antiapoptotic protein genes (Bcl-2 (p = 0.028) and Bcl-6 (p = 0.039)). The cleaved caspase-3 was positively modulated by the AE-Ac inducing thus cell death by apoptosis. AE-Ac showed inhibitory effects on the expression of genes involved in cancer progression making it a potential health intervention agent that can be exploited in cancer therapy protocols.

Chronic Treatment with Nigella sativa Oil Exerts Antimanic Properties and Reduces Brain Inflammation in Rats

Nigella sativa (NS) is a native herb consumed habitually in several countries worldwide, possessing manifold therapeutic properties. Among them, anti-inflammatory features have been reported, presumably relating to mechanisms involved in the nuclear factor kappa-B pathway, among others. Given the observed association between neuroimmune factors and mental illness, the primary aim of the present study was to examine the effects of chronic NS use on manic-like behavior in rats, as well as analyze levels of brain inflammatory mediators following NS intake. Using male and female rats, baseline tests were performed; thereafter, rats were fed either regular food (control) or NS-containing food (treatment) for four weeks. Following intervention, behavioral tests were induced (an open field test, sucrose consumption test, three-chamber sociality test, and amphetamine-induced hyperactivity test). Subsequently, brain samples were extracted, and inflammatory mediators were evaluated, including interleukin-6, leukotriene B4, prostaglandin E2, tumor necrosis factor-α, and nuclear phosphorylated-p65. Our findings show NS to result in a marked antimanic-like effect, in tandem with a positive modulation of select inflammatory mediators among male and female rats. The findings reinforce the proposed therapeutic advantages relating to NS ingestion.

Mitochondria in depression: The dysfunction of mitochondrial energy metabolism and quality control systems

BACKGROUND

Depression is the most disabling neuropsychiatric disorder, causing difficulties in daily life activities and social interactions. The exact mechanisms of depression remain largely unclear. However, some studies have shown that mitochondrial dysfunction would play a crucial role in the occurrence and development of depression.

AIMS

To summarize the known knowledge about the role of mitochondrial dysfunction in the pathogenesis of depression.

METHODS

We review the recent literature， including 105 articles, to summarize the mitochondrial energy metabolism and quality control systems in the occurrence and development of depression. Some antidepressants which may exert their effects by improving mitochondrial function are also discussed.

RESULTS

Impaired brain energy metabolism and (or) damaged mitochondrial quality control systems have been reported not only in depression patients but in animal models of depression. Although the classical antidepressants have not been specially designed to target mitochondria, the evidence suggests that many antidepressants may exert their effects by improving mitochondrial function.

CONCLUSIONS

This brief review focuses on the findings that implicate mitochondrial dysfunction and the quality control systems as important etiological factors in the context of depressive disorders. It will help us to understand the various concepts of mitochondrial dysfunction in the pathogenesis of depression, and to explore novel and more targeted therapeutic approaches for depression.

PGAM5 knockout causes depressive-like behaviors in mice via ATP deficiency in the prefrontal cortex

INTRODUCTION

Major depressive disorder (MDD) affects about 17% population in the world. Although abnormal energy metabolism plays an important role in the pathophysiology of MDD, however, how deficiency of adenosine triphosphate (ATP) products affects emotional circuit and what regulates ATP synthesis are still need to be elaborated.

AIMS

Our study aimed to investigate how deficiency of PGAM5-mediated depressive behavior.

RESULTS

We firstly discovered that PGAM5 knockout (PGAM5-/- ) mice generated depressive-like behaviors. The phenotype was reinforced by the observation that chronic unexpected mild stress (CUMS)-induced depressive mice exhibited lowered expression of PGAM5 in prefrontal cortex (PFC), hippocampus (HIP), and striatum. Next, we found, with the using of functional magnetic resonance imaging (fMRI), that the functional connectivity between PFC reward system and the PFC volume were reduced in PGAM5-/- mice. PGAM5 ablation resulted in the loss of dendritic spines and lowered density of PSD95 in PFC, but not in HIP. Finally, we found that PGAM5 ablation led to lowered ATP concentration in PFC, but not in HIP. Coimmunoprecipitation study showed that PGAM5 directly interacted with the ATP F1 F0 synthase without influencing the interaction between ATP F1 F0 synthase and Bcl-xl. We then conducted ATP administration to PGAM5-/- mice and found that ATP could rescue the behavioral and neuronal phenotypes of PGAM5-/- mice.

CONCLUSIONS

Our findings provide convincing evidence that PGAM5 ablation generates depressive-like behaviors via restricting neuronal ATP production so as to impair the number of neuronal spines in PFC.

The molecular mechanism of polysaccharides in combating major depressive disorder: A comprehensive review

Major depressive disorder (MDD) is a complex psychiatric condition with diverse etiological factors. Typical pathological features include decreased cerebral cortex, subcortical structures, and grey matter volumes, as well as monoamine transmitter dysregulation. Although medications exist to treat MDD, unmet needs persist due to limited efficacy, induced side effects, and relapse upon drug withdrawal. Polysaccharides offer promising new therapies for MDD, demonstrating antidepressant effects with minimal side effects and multiple targets. These include neurotransmitter, neurotrophin, neuroinflammation, hypothalamic-pituitary-adrenal axis, mitochondrial function, oxidative stress, and intestinal flora regulation. This review explores the latest advancements in understanding the pharmacological actions and mechanisms of polysaccharides in treating major depression. We discuss the impact of polysaccharides' diverse structures and properties on their pharmacological actions, aiming to inspire new research directions and facilitate the discovery of novel anti-depressive drugs.

Photobiomodulation therapy alleviates repeated closed head injury-induced anxiety-like behaviors

Repeated closed head injury (rCHI) is one of the most common brain injuries. Although extensive studies have focused on how to treat rCHI-induced brain injury and reduce the possibility of developing memory deficits, the prevention of rCHI-induced anxiety has received little research attention. The current study was designed to assess the effects of photobiomodulation (PBM) therapy in preventing anxiety following rCHI. The rCHI disease model was constructed by administering three repeated closed-head injuries within an interval 5 days. 2-min daily PBM therapy using an 808 nm continuous wave laser at 350 mW/cm2 on the scalp was implemented for 20 days. We found that PBM significantly ameliorated rCHII-induced anxiety-like behaviors, neuronal apoptosis, neuronal injury, promotes astrocyte/microglial polarization to anti-inflammatory phenotype, preserves mitochondrial fusion-related protein MFN2, attenuates the elevated mitochondrial fission-related protein DRP1, and mitigates neuronal senescence. We concluded that PBM therapy possesses great potential in preventing anxiety following rCHI.

Targeting mitochondrial dynamics of morphine-responsive dopaminergic neurons ameliorates opiate withdrawal

Converging studies demonstrate the dysfunction of the dopaminergic neurons following chronic opioid administration. However, the therapeutic strategies targeting opioid-responsive dopaminergic ensembles that contribute to the development of opioid withdrawal remain to be elucidated. Here, we used the neuronal activity-dependent Tet-Off system to label dopaminergic ensembles in response to initial morphine exposure (Mor-Ens) in the ventral tegmental area (VTA). Fiber optic photometry recording and transcriptome analysis revealed downregulated spontaneous activity and dysregulated mitochondrial respiratory, ultrastructure, and oxidoreductase signal pathways after chronic morphine administration in these dopaminergic ensembles. Mitochondrial fragmentation and the decreased mitochondrial fusion gene mitofusin 1 (Mfn1) were found in these ensembles after prolonged opioid withdrawal. Restoration of Mfn1 in the dopaminergic Mor-Ens attenuated excessive oxidative stress and the development of opioid withdrawal. Administration of Mdivi-1, a mitochondrial fission inhibitor, ameliorated the mitochondrial fragmentation and maladaptation of the neuronal plasticity in these Mor-Ens, accompanied by attenuated development of opioid withdrawal after chronic morphine administration, without affecting the analgesic effect of morphine. These findings highlighted the plastic architecture of mitochondria as a potential therapeutic target for opioid analgesic-induced substance use disorders.

Increased expression of ER stress, inflammasome activation, and mitochondrial biogenesis-related genes in peripheral blood mononuclear cells in major depressive disorder

A subset of major depressive disorder (MDD) is characterized by immune system dysfunction, but the intracellular origin of these immune changes remains unclear. Here we tested the hypothesis that abnormalities in the endoplasmic reticulum (ER) stress, inflammasome activity and mitochondrial biogenesis contribute to the development of systemic inflammation in MDD. RT-qPCR was used to measure mRNA expression of key organellar genes from peripheral blood mononuclear cells (PBMCs) isolated from 186 MDD and 67 healthy control (HC) subjects. The comparative CT (2-ΔΔCT) method was applied to quantify mRNA expression using GAPDH as the reference gene. After controlling for age, sex, BMI, and medication status using linear regression models, expression of the inflammasome (NLRC4 and NLRP3) and the ER stress (XBP1u, XBP1s, and ATF4) genes was found to be significantly increased in the MDD versus the HC group. After excluding outliers, expression of the inflammasome genes was no longer statistically significant but expression of the ER stress genes (XBP1u, XBP1s, and ATF4) and the mitochondrial biogenesis gene, MFN2, was significantly increased in the MDD group. ASC and MFN2 were positively correlated with serum C-reactive protein concentrations. The altered expression of inflammasome activation, ER stress, and mitochondrial biogenesis pathway components suggest that dysfunction of these organelles may play a role in the pathogenesis of MDD.

Promising new pharmacological targets for depression: The search for efficacy

Pharmacological treatment of major depressive disorder (MDD) still relies on the use of serotonergic drugs, despite their limited efficacy. A few mechanistically new drugs have been developed in recent years, but many fail in clinical trials. Several hypotheses have been proposed to explain MDD pathophysiology, indicating that physiological processes such as neuroplasticity, circadian rhythms, and metabolism are potential targets. Here, we review the current state of pharmacological treatments for MDD, as well as the preclinical and clinical evidence for an antidepressant effect of molecules that target non-serotonergic systems. We offer some insights into the challenges facing the development of new antidepressant drugs, and the prospect of finding more effectiveness for each target discussed.

BNIP3L/NIX-mediated mitophagy alleviates passive stress-coping behaviors induced by tumor necrosis factor-α

Recent studies based on animal models of various neurological disorders have indicated that mitophagy, a selective autophagy that eliminates damaged and superfluous mitochondria through autophagic degradation, may be involved in various neurological diseases. As an important mechanism of cellular stress response, much less is known about the role of mitophagy in stress-related mood disorders. Here, we found that tumor necrosis factor-α (TNF-α), an inflammation cytokine that plays a particular role in stress responses, impaired the mitophagy in the medial prefrontal cortex (mPFC) via triggering degradation of an outer mitochondrial membrane protein, NIP3-like protein X (NIX). The deficits in the NIX-mediated mitophagy by TNF-α led to the accumulation of damaged mitochondria, which triggered synaptic defects and behavioral abnormalities. Genetic ablation of NIX in the excitatory neurons of mPFC caused passive coping behaviors to stress, and overexpression of NIX in the mPFC improved TNF-α-induced synaptic and behavioral abnormalities. Notably, ketamine, a rapid on-set and long-lasting antidepressant, reversed the TNF-α-induced behavioral abnormalities through activation of NIX-mediated mitophagy. Furthermore, the downregulation of NIX level was also observed in the blood of major depressive disorder patients and the mPFC tissue of animal models. Infliximab, a clinically used TNF-α antagonist, alleviated both chronic stress- and inflammation-induced behavioral abnormalities via restoring NIX level. Taken together, these results suggest that NIX-mediated mitophagy links inflammation signaling to passive coping behaviors to stress, which underlies the pathophysiology of stress-related emotional disorders.

The Protective Effect of Lithium Against Rotenone may be Evolutionarily Conserved: Evidence from Eisenia fetida, a Primitive Animal with a Ganglionic Brain

Chronic exposure to stress is a non-adaptive situation that is associated with mitochondrial dysfunction and the accumulation of reactive oxygen species (ROS), especially superoxide anion (SA). This accumulation of ROS produces damage-associated molecular patterns (DAMPs), which activate chronic inflammatory states and behavioral changes found in several mood disorders. In a previous study, we observed that an imbalance of SA triggered by rotenone (Ro) exposure caused evolutionarily conserved oxi-inflammatory disturbances and behavioral changes in Eisenia fetida earthworms. These results supported our hypothesis that SA imbalance triggered by Ro exposure could be attenuated by lithium carbonate (LC), which has anti-inflammatory properties. The initial protocol exposed earthworms to Ro (30 nM) and four different LC concentrations. LC at a concentration of 12.85 mg/L decreased SA and nitric oxide (NO) levels and was chosen to perform complementary assays: (1) neuromuscular damage evaluated by optical and scanning electron microscopy (SEM), (2) innate immune inefficiency by analysis of Eisenia spp. extracellular neutrophil traps (eNETs), and (3) behavioral changes. Gene expression was also evaluated involving mitochondrial (COII, ND1), inflammatory (EaTLR, AMP), and neuronal transmission (nAchR α5). LC attenuated the high melanized deposits in the circular musculature, fiber disarrangement, destruction of secretory glands, immune inefficiency, and impulsive behavior pattern triggered by Ro exposure. However, the effects of LC and Ro on gene expression were more heterogeneous. In summary, SA imbalance, potentially associated with mitochondrial dysfunction, appears to be an evolutionary component triggering oxidative, inflammatory, and behavioral changes observed in psychiatric disorders that are inhibited by LC exposure.

Mitochondrial fission drives neuronal metabolic burden to promote stress susceptibility in male mice

Neurons are particularly susceptible to energy fluctuations in response to stress. Mitochondrial fission is highly regulated to generate ATP via oxidative phosphorylation; however, the role of a regulator of mitochondrial fission in neuronal energy metabolism and synaptic efficacy under chronic stress remains elusive. Here, we show that chronic stress promotes mitochondrial fission in the medial prefrontal cortex via activating dynamin-related protein 1 (Drp1), resulting in mitochondrial dysfunction in male mice. Both pharmacological inhibition and genetic reduction of Drp1 ameliorates the deficit of excitatory synaptic transmission and stress-related depressive-like behavior. In addition, enhancing Drp1 fission promotes stress susceptibility, which is alleviated by coenzyme Q10, which potentiates mitochondrial ATP production. Together, our findings unmask the role of Drp1-dependent mitochondrial fission in the deficits of neuronal metabolic burden and depressive-like behavior and provides medication basis for metabolism-related emotional disorders.

Post-Stroke Neuropsychiatric Complications: Types, Pathogenesis, and Therapeutic Intervention

Almost all stroke survivors suffer physical disabilities and neuropsychiatric disturbances, which can be briefly divided into post-stroke neurological diseases and post-stroke psychiatric disorders. The former type mainly includes post-stroke pain, post-stroke epilepsy, and post-stroke dementia while the latter one includes post-stroke depression, post-stroke anxiety, post-stroke apathy and post-stroke fatigue. Multiple risk factors are related to these post-stroke neuropsychiatric complications, such as age, gender, lifestyle, stroke type, medication, lesion location, and comorbidities. Recent studies have revealed several critical mechanisms underlying these complications, namely inflammatory response, dysregulation of the hypothalamic pituitary adrenal axis, cholinergic dysfunction, reduced level of 5-hydroxytryptamine, glutamate-mediated excitotoxicity and mitochondrial dysfunction. Moreover, clinical efforts have successfully given birth to many practical pharmaceutic strategies, such as anti-inflammatory medications, acetylcholinesterase inhibitors, and selective serotonin reuptake inhibitors, as well as diverse rehabilitative modalities to help patients physically and mentally. However, the efficacy of these interventions is still under debate. Further investigations into these post-stroke neuropsychiatric complications, from both basic and clinical perspectives, are urgent for the development of effective treatment strategies.

Does decreased autophagy and dysregulation of LC3A in astrocytes play a role in major depressive disorder?

Astrocytic dysfunction contributes to the molecular pathogenesis of major depressive disorder (MDD). However, the astrocytic subtype that mainly contributes to MDD etiology and whether dysregulated autophagy in astrocytes is associated with MDD remain unknown. Using a single-nucleus RNA sequencing (snRNA-seq) atlas, three astrocyte subtypes were identified in MDD, while C2 State-1Q astrocytes showed aberrant changes in both cell proportion and most differentially expressed genes compared with other subtypes. Moreover, autophagy pathways were commonly inhibited in astrocytes in the prefrontal cortices (PFCs) of patients with MDD, especially in C2 State-1Q astrocytes. Furthermore, by integrating snRNA-seq and bulk transcriptomic data, we found significant reductions in LC3A expression levels in the PFC region of CUMS-induced depressed mice, as well as in postmortem PFC tissues and peripheral blood samples from patients with MDD. These results were further validated by qPCR using whole-blood samples from patients with MDD and healthy controls. Finally, LC3A expression in the whole blood of patients with MDD was negatively associated with the severity of depressive symptoms. Overall, our results underscore autophagy inhibition in PFC astrocytes as a common molecular characteristic in MDD and might reveal a novel potential diagnostic marker LC3A.

Exposure to salinomycin dysregulates interplay between mitophagy and oxidative response to damage the porcine jejunal cells

Salinomycin (SAL) has caused widespread pollution as a feed additive and growth promoter in livestock such as pigs, exerting a negative impact on public health. The toxicity mechanism of SAL has been widely studied in chickens, but the underlying mechanisms of SAL-induced toxicity to pigs and the ecosystem remain undefined. In this study, we explored the potential damage of SAL in IPEC-J2 cells to identify the effects of excessive SAL on the interplay between mitophagy and oxidative stress. The results showed that a concentration-dependent response was observed for SAL in altering cellular morphology and inducing cell death in IPEC-J2 cells, including the induction of cell cycle arrest and lactic dehydrogenase (LDH) release. Meanwhile, we found that excessive SAL led to oxidative damage by activating the Nrf2/Keap1/HO-1 pathway, accompanied by reactive oxygen species (ROS) elevation and the reduction of antioxidant enzyme activity. We also found that PINK1/Parkin-dependent mitophagy was activated by SAL exposure, particularly with mitochondrial membrane potential reduction. Interestingly, SAL-induced oxidative damages were prevented after the autophagy inhibitor 3-methyladenine (3-MA) treatment, and mitophagy was alleviated following ROS scavenger (N-acetylcysteine, NAC) treatment. Overall, our findings showed that SAL stimulated oxidative stress and mitophagy in IPEC-J2 cells resulting in cellular injury, and there was a strong connection between SAL-induced oxidative stress and mitophagy. Targeting ROS/PINK1/Parkin-dependent mitophagy and oxidative stress could be a novel protective mechanism in SAL-induced cell damage.

Mitochondrial dysfunction: A fatal blow in depression

Mitochondria maintain the normal physiological function of nerve cells by producing sufficient cellular energy and performing crucial roles in maintaining the metabolic balance through intracellular Ca2+ homeostasis, oxidative stress, and axonal development. Depression is a prevalent psychiatric disorder with an unclear pathophysiology. Damage to the hippocampal neurons is a key component of the plasticity regulation of synapses and plays a critical role in the mechanism of depression. There is evidence suggesting that mitochondrial dysfunction is associated with synaptic impairment. The maintenance of mitochondrial homeostasis includes quantitative maintenance and quality control of mitochondria. Mitochondrial biogenesis produces new and healthy mitochondria, and mitochondrial dynamics cooperates with mitophagy to remove damaged mitochondria. These processes maintain mitochondrial population stability and exert neuroprotective effects against early depression. In contrast, mitochondrial dysfunction is observed in various brain regions of patients with major depressive disorders. The accumulation of defective mitochondria accelerates cellular nerve dysfunction. In addition, impaired mitochondria aggravate alterations in the brain microenvironment, promoting neuroinflammation and energy depletion, thereby exacerbating the development of depression. This review summarizes the influence of mitochondrial dysfunction and the underlying molecular pathways on the pathogenesis of depression. Additionally, we discuss the maintenance of mitochondrial homeostasis as a potential therapeutic strategy for depression.

Targeting mitophagy for depression amelioration: a novel therapeutic strategy

Major depressive disorder is a global psychiatric condition characterized by persistent low mood and anhedonia, which seriously jeopardizes the physical and mental well-being of affected individuals. While various hypotheses have been proposed to explicate the etiology of depression, the precise pathogenesis and effective treatment of this disorder remain elusive. Mitochondria, as the primary organelles responsible for cellular energy production, possess the ability to meet the essential energy demands of the brain. Research indicated that the accumulation of damaged mitochondria is associated with the onset of depression. Mitophagy, a type of cellular autophagy, specifically targets and removes excess or damaged mitochondria. Emerging evidence demonstrated that mitophagy dysfunction was involved in the progression of depression, and several pharmacological interventions that stimulating mitophagy exerted excellent antidepressant actions. We provided an overview of updated advancements on the regulatory mechanism of mitophagy and the mitophagy abnormality in depressed patients and animals, as well as in cell models of depression. Meanwhile, various therapeutic strategies to restore mitophagy for depression alleviation were also discussed in this review.

Mitochondria of intestinal epithelial cells in depression: Are they at a crossroads of gut-brain communication?

The role of gut dysbiosis in depression is well established. However, recent studies have shown that gut microbiota is regulated by intestinal epithelial cell (IEC) mitochondria, which has yet to receive much attention. This review summarizes the recent developments about the critical role of IEC mitochondria in actively maintaining gut microbiota, intestinal metabolism, and immune homeostasis. We propose that IEC mitochondrial dysfunction alters gut microbiota composition, participates in cell fate, mediates oxidative stress, activates the peripheral immune system, causes peripheral inflammation, and transmits peripheral signals through the vagus and enteric nervous systems. These pathological alterations lead to brain inflammation, disruption of the blood-brain barrier, activation of the hypothalamic-pituitary-adrenal axis, activation of microglia and astrocytes, induction of neuronal loss, and ultimately depression. Furthermore, we highlight the prospect of treating depression through the mitochondria of IECs. These new findings suggest that the mitochondria of IECs may be a newly found important factor in the pathogenesis of depression and represent a potential new strategy for treating depression.

Comorbidity between major depressive disorder and physical diseases: a comprehensive review of epidemiology, mechanisms and management

Populations with common physical diseases - such as cardiovascular diseases, cancer and neurodegenerative disorders - experience substantially higher rates of major depressive disorder (MDD) than the general population. On the other hand, people living with MDD have a greater risk for many physical diseases. This high level of comorbidity is associated with worse outcomes, reduced adherence to treatment, increased mortality, and greater health care utilization and costs. Comorbidity can also result in a range of clinical challenges, such as a more complicated therapeutic alliance, issues pertaining to adaptive health behaviors, drug-drug interactions and adverse events induced by medications used for physical and mental disorders. Potential explanations for the high prevalence of the above comorbidity involve shared genetic and biological pathways. These latter include inflammation, the gut microbiome, mitochondrial function and energy metabolism, hypothalamic-pituitary-adrenal axis dysregulation, and brain structure and function. Furthermore, MDD and physical diseases have in common several antecedents related to social factors (e.g., socioeconomic status), lifestyle variables (e.g., physical activity, diet, sleep), and stressful live events (e.g., childhood trauma). Pharmacotherapies and psychotherapies are effective treatments for comorbid MDD, and the introduction of lifestyle interventions as well as collaborative care models and digital technologies provide promising strategies for improving management. This paper aims to provide a detailed overview of the epidemiology of the comorbidity of MDD and specific physical diseases, including prevalence and bidirectional risk; of shared biological pathways potentially implicated in the pathogenesis of MDD and common physical diseases; of socio-environmental factors that serve as both shared risk and protective factors; and of management of MDD and physical diseases, including prevention and treatment. We conclude with future directions and emerging research related to optimal care of people with comorbid MDD and physical diseases.

The nano-windmill exerts superior anti-inflammatory effects via reducing choline uptake to inhibit macrophage activation

Macrophages' activation plays a central role during the development and progression of inflammation, while the regulation of metabolic reprogramming of macrophages has been recently identified as a novel strategy for anti-inflammatory therapies. Our previous studies have found that tetrahedral framework nucleic acid (tFNA) plays a mild anti-inflammatory effect by inhibiting macrophage activation, but the specific mechanism remains unclear. Here, by metabolomics and RNA sequencing, choline uptake is identified to be significantly repressed by decreased slc44a1 expression in tFNA-treated activated macrophages. Inspired by this result, combined with the excellent delivery capacities of tFNA, siR-slc44a1 is loaded into the tFNA to develop a new tFNA-based small interfering RNA (siRNA) delivery system named 'nano-windmill,' which exhibits a synergetic role by targeting slc44a1, finally blowing up the anti-inflammatory effects of tFNA to inhibit macrophages activation via reducing choline uptake. By confirming its anti-inflammatory effects in chronic (periodontitis) and acute (sepsis) inflammatory disease, the tFNA-based nanomedicine developed for inflammatory diseases may provide broad prospects for tFNA upgrading and various biological applications such as anti-inflammatory.

Hydrogen Sulfide Prevents LPS-Induced Depression-like Behavior through the Suppression of NLRP3 Inflammasome and Pyroptosis and the Improvement of Mitochondrial Function in the Hippocampus of Mice

Hydrogen sulfide (H2S) has been implicated to have antidepressive effects. We sought to investigate the prevention effects of H2S donor NaHS on depression-like behavior induced by lipopolysaccharide (LPS) in mice and its potential mechanisms. Sucrose preference, force swimming, open field, and elevate zero maze were used to evaluate depression-like behavior. NF-κB and NLRP3 inflammasome activation and mitochondrial function in the hippocampus were determined. It was found that depression-like behavior induced by LPS was prevented by NaHS pretreatment. LPS caused NF-κB and NLRP3 inflammasome activation in the hippocampus as evidenced by increased phosphorylated-p65 levels and increased NLRP3, ASC, caspase-1, and mature IL-1β levels in the hippocampus, which were also blocked by NaHS. LPS increased GSDMD-N levels and TUNEL-positive cells in the hippocampus, which was prevented by NaHS. Abnormal mitochondrial morphology in the hippocampus was found in LPS-treated mice. Mitochondrial membrane potential and ATP production were reduced, and ROS production was increased in the hippocampus of LPS-treated mice. NaHS pretreatment improved impaired mitochondrial morphology and increased membrane potential and ATP production and reduced ROS production in the hippocampus of LPS-treated mice. Our data indicate that H2S prevents LPS-induced depression-like behaviors by inhibiting NLRP3 inflammasome activation and pyroptosis and improving mitochondrial function in the hippocampus.

Mitophagy: A Bridge Linking HMGB1 and Parkinson's Disease Using Adult Zebrafish as a Model Organism

High-mobility group box 1 (HMGB1) has been implicated as a key player in two critical factors of Parkinson's disease (PD): mitochondrial dysfunction and neuroinflammation. However, the specific role of HMGB1 in PD remains elusive. We investigated the effect of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration on mitochondrial dysfunction and HMGB1-associated inflammatory genes as well as locomotor activity in zebrafish, aiming to elucidate the role of HMGB1 in PD. Adult zebrafish received MPTP injections, and locomotor activity was measured at 24- and 48-h post-administration. Gene expression levels related to mitophagy (fis1, pink1, and park2) and HMGB1-mediated inflammation (hmgb1, tlr4, and nfkb) were quantified through RT-qPCR analysis. Following MPTP injection, the significant increase in transcript levels of fis1, pink1, and park2 indicated notable changes in PINK1/Parkin mitophagy, while the upregulation of hmgb1, tlr4, and nfkb genes pointed to the activation of the HMGB1/TLR4/NFκB inflammatory pathway. Furthermore, MPTP-injected zebrafish exhibited decreased locomotor activity, evident through reduced distance travelled, mean speed, and increased freezing durations. HMGB1 plays a major role in cellular processes as it is involved in both the mitophagy process and functions as a pro-inflammatory protein. MPTP administration in adult zebrafish activated mitophagy and inflammatory signaling, highlighting the significant role of HMGB1 as a mediator in both processes and further emphasizing its significant contribution to PD pathogenesis.

Depression among Patients with an Implanted Left Ventricular Assist Device: Uncovering Pathophysiological Mechanisms and Implications for Patient Care

Depression is a common and devastating mental illness associated with increased morbidity and mortality, partially due to elevated rates of suicidal attempts and death. Select patients with end-stage heart failure on a waiting-list for a donor heart undergo left ventricular assist device (LVAD) implantation. The LVAD provides a circulatory flow of oxygenated blood to the body, mimicking heart functionality by operating on a mechanical technique. LVAD improves functional capacity and survivability among patients with end-stage heart failure. However, accumulating data suggests that LVAD recipients suffer from an increased incidence of depression and suicide attempts. There is scarce knowledge regarding the pathological mechanism and appropriate treatment approach for depressed LVAD patients. This article summarizes the current evidence on the association between LVAD implantation and occurrence of depression, suggesting possible pathological mechanisms underlying the device-associated depression and reviewing the current treatment strategies. The summarized data underscores the need for a rigorous pre-(LVAD)-implantation psychiatric evaluation, continued post-implantation mental health assessment, and administration of antidepressant treatment as necessary.

Mitochondria-wide association study observed significant interactions of mitochondrial respiratory and the inflammatory in the development of anxiety and depression

The aim of this study was to investigate the possible interaction of mitochondrial dysfunction and inflammatory cytokines in the risk of anxiety and depression. We utilized the UK Biobank for the sample of this study. A mitochondria-wide association(MiWAS) and interaction analysis was performed to investigate the interaction effects of mitochondrial DNA (mtDNA)×C-reactive protein (CRP) on the risks of self-reported anxiety (N = 72,476), general anxiety disorder (GAD-7) scores (N = 80,853), self-reported depression (N = 80,778), Patient Health Questionnaire (PHQ-9) scores (N = 80,520) in total samples, females and males, respectively, adjusting for sex, age, Townsend deprivation index (TDI), education score, alcohol intake, smoking and 10 principal components. In all, 25 mtSNPs and 10 mtSNPs showed significant level of association with self-reported anxiety and GAD-7 score respectively. A total of seven significant mtDNA × CRP interactions were found for anxiety, such as m.3915G>A(MT-ND1) for self-reported anxiety in total subjects (P = 6.59 × 10^-3), m.4561T>C(MT-ND2) (P = 3.04 × 10^-3) for GAD-7 score in total subjects. For depression, MiWAS identified 17 significant mtSNPs for self-reported depression and 14 significant mtSNPs for PHQ-9 scores. 17 significant mtDNA associations (2 for self-reported depression and 15 for PHQ-9 score) was identified, such as m.14869G>A(MT-CYB; P = 2.22 × 10^-3) associated with self-reported depression and m.4561T>C (MT-ND2; P value = 3.02 × 10^-8) associated with PHQ-9 score in all subjects. In addition, 5 common mtDNA shared with anxiety and depression were found in MiWAS, and 4 common mtDNA variants were detected to interact with CRP for anxiety and depression, such as m.9899T>C(MT-CO3). Our study suggests the important interaction effects of mitochondrial function and CRP on the risks of anxiety and depression.

Identification of mitophagy-related biomarkers and immune infiltration in major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a life-threatening and debilitating mental health condition. Mitophagy, a form of selective autophagy that eliminates dysfunctional mitochondria, is associated with depression. However, studies on the relationship between mitophagy-related genes (MRGs) and MDD are scarce. This study aimed to identify potential mitophagy-related biomarkers for MDD and characterize the underlying molecular mechanisms.

METHODS

The gene expression profiles of 144 MDD samples and 72 normal controls were retrieved from the Gene Expression Omnibus database, and the MRGs were extracted from the GeneCards database. Consensus clustering was used to determine MDD clusters. Immune cell infiltration was evaluated using CIBERSORT. Functional enrichment analyses were performed to determine the biological significance of mitophagy-related differentially expressed genes (MR-DEGs). Weighted gene co-expression network analysis, along with a network of protein-protein interactions (PPI), was used to identify key modules and hub genes. Based on the least absolute shrinkage and selection operator analysis and univariate Cox regression analysis, a diagnostic model was constructed and evaluated using receiver operating characteristic curves and validated with training data and external validation data. We reclassified MDD into two molecular subtypes according to biomarkers and evaluated their expression levels.

RESULTS

In total, 315 MDD-related MR-DEGs were identified. Functional enrichment analyses revealed that MR-DEGs were mainly enriched in mitophagy-related biological processes and multiple neurodegenerative disease pathways. Two distinct clusters with diverse immune infiltration characteristics were identified in the 144 MDD samples. MATR3, ACTL6A, FUS, BIRC2, and RIPK1 have been identified as potential biomarkers of MDD. All biomarkers showed varying degrees of correlation with immune cells. In addition, two molecular subtypes with distinct mitophagy gene signatures were identified.

CONCLUSIONS

We identified a novel five-MRG gene signature that has excellent diagnostic performance and identified an association between MRGs and the immune microenvironment in MDD.