BDNF - a key transducer of antidepressant effects

Plasma brain-derived neurotrophic factor before hemodialysis reduces the risk of depression in patients with chronic renal failure

BACKGROUND

Neurotrophins are related with depressive disorders. Significant neurotrophins variations occur during renal replacement therapy, but whether peri-hemodialysis availability is associated with depression in patients with Chronic Kidney Disease (CKD) is yet unclear.

AIM

To determine dynamic concentrations of neurotrophins in the peri-hemodialysis range and their association with depressive symptoms in patients with CKD.

METHODS

Pre-, and post-hemodialysis plasma concentrations of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), as well as their plasma clearance rates, were determined (multiplexing) in patients with stage 5 CKD. Depressive symptoms, as assessed by the Beck Depression Inventory-II (BDI-II), were determined. Finally, the bioavailability of BDNF and NGF was related to the score of depressive symptoms.

RESULTS

Fifty-three patients were divided according to depressive symptoms. Pre-hemodialysis plasma BDNF was lower in patients with depressive disorder; whereas basal BDNF value >220 pg/mL independently reduced the risk for depressive disorder (Odds Ratio 0.23, p = 0.047) at uni- and multivariate analysis. Post-hemodialysis concentration and clearance rate of neurotrophins were not related with depressive symptoms.

CONCLUSION

Higher plasma BDNF before hemodialysis reduces the risk of mild depression in patients with CKD under renal replacement therapy.

Study on the comorbid mechanisms of sarcopenia and late-life depression

The increasing global aging population has brought greater focus to age-related diseases, particularly muscle-brain comorbidities such as sarcopenia and late-life depression. Sarcopenia, defined by the gradual loss of muscle mass and function, is notably prevalent among older individuals, while late-life depression profoundly affects their mental health and overall well-being. Epidemiological evidence suggests a high co-occurrence of these two conditions, although the precise biological mechanisms linking them remain inadequately understood. This review synthesizes the existing body of literature on sarcopenia and late-life depression, examining their definitions, prevalence, clinical presentations, and available treatments. The goal is to clarify the potential connections between these comorbidities and offer a theoretical framework for the development of future preventive and therapeutic strategies.

Selective Noradrenergic Activation of BDNF Translation by Mirtazapine

Antidepressants are known for their neurotrophic effects, particularly through the regulation of brain-derived neurotrophic factor (BDNF) expression. Mirtazapine, a tetracyclic noradrenergic and specific serotonergic antidepressant (NaSSA) has been observed to upregulate BDNF, though its underlying mechanism remains unclear. In this study, we used the human neuroblastoma SH-SY5Y cell line to investigate whether mirtazapine could enhance BDNF translation by modulating serotonin and/or norepinephrine and their receptors. A 1-h stimulation with 1 or 10 µM mirtazapine led to downregulation of serotonergic receptors 5HT1A, while increasing ADRA2A and ADRB2 receptors. Mirtazapine at 10 µM upregulated endogenous BDNF after 3h, but not 1h stimulation. To investigate the translation of major BDNF transcripts, we used chimeric BDNF-luciferase constructs with the untranslated 5'UTR exons I, IIc, IV, or VI, and the long version of the 3'UTR. Luciferase assays and Western blotting revealed that mirtazapine selectively enhanced exon-IIc-BDNF-long3'UTR-Luciferase translation. This increase was associated with norepinephrine release and was inhibited by blocking ADRA2A or ADRB2 adrenoceptors for the exon-IIc-BDNF-long3'UTR-Luciferase, and ADR2B for endogenous BDNF. These findings provide a new perspective on the critical role of the noradrenergic system in mediating mirtazapine's effects on BDNF translation. We propose a novel mechanism of action in which mirtazapine promotes norepinephrine release and noradrenergic responses by upregulating ADRA2A and ADRB2 while downregulating serotonergic receptors.

BDNF and proBDNF serum levels during antidepressant treatment in adolescent girls with a first-lifetime episode of depression: A prospective case-controlled study

INTRODUCTION

As one of the most promising biomarkers in depression course and treatment, the brain-derived neurotrophic factor (BDNF) has been identified as a possible predictor of antidepressant treatment outcomes in the adult population. However, studies on this subject in the developmental population are lacking. We aimed to verify the changes in serum BDNF, proBDNF, and BDNF/proBDNF ratio levels during antidepressant treatment in adolescents diagnosed with depressive episodes. We also investigated these parameters as predictors of antidepressant treatment outcomes.

MATERIAL AND METHODS

Thirty female inpatients, aged 11-17, diagnosed with a first-lifetime depressive episode were assessed at two time-points: before (t0) and after (t1) the period of antidepressant treatment and compared with thirty age-matched healthy girls. The assessment at t0 and t1 involved BDNF and proBDNF serum levels (analyzed with the ELISA method) and standardized depressive symptoms scales.

RESULTS

BDNF serum levels decreased significantly with the antidepressant treatment in the studied group (p = 0.0224). This effect was still present in the subgroup of responders (p = 0.0179) but not among non-responders (p = 0.2184). Responders had a significantly higher initial BDNF/proBDNF ratio than non-responders. The BDNF/proBDNF ratio at t0 could predict the remission status at t1 with a sensitivity of 66.67 % and a specificity of 81.25 % (p = 0.0327).

CONCLUSIONS

BDNF serum levels tend to decrease with successful antidepressant treatment in adolescent girls treated for the first episode of depression. Pretreatment BDNF/proBDNF ratio should be considered a possible biomarker predictive of antidepressant treatment response in adolescent girls.

Activation of Hippocampal Neuronal NADPH Oxidase NOX2 Promotes Depressive-Like Behaviour and Cognition Deficits in Chronic Restraint Stress Mouse Model

BACKGROUND

Nicotinamide adenosine dinucleotide phosphate oxidases (NOX) play important roles in mediating stress-induced depression. Three NOX isotypes are expressed mainly in the brain: NOX2, NOX3 and NOX4. In this study, the expression and cellular sources of these NOX isoforms was investigated in the context of stress-induced depression.

METHODS

Chronic restraint stress (CRS)-induced depressive-like behaviour and cognitive deficits were evaluated by tail suspension tests, forced swimming tests and the Morris water maze test. Hippocampal NOX expression was determined by immunofluorescence staining and western blotting. The hippocampal levels of the brain-derived neurotrophic factor (BDNF) mRNA were determined via quantitative real-time -polymerase chain reaction. Glucocorticoid levels in the hippocampus were measured using ELISA kits.

RESULTS

In the mouse CRS model, a significant increase in NOX2 expression was observed in the hippocampus, whereas no significant changes in NOX3 and NOX4 expression were detected. Next, NOX2 expression was primarily localised to neurons (NeuN+) but not microglia (Iba-1+) or astrocytes (GFAP+). Treatment with gp91ds-tat, a specific NOX2 inhibitor, effectively mitigated the behavioural deficits induced by CRS. The decreased expression of the BDNF mRNA in the hippocampus of CRS mice was restored upon gp91ds-tat treatment. A positive correlation was identified between neuronal NOX2 expression and serum glucocorticoid levels.

CONCLUSIONS

Our study indicated that neuronal NOX2 may be a critical mediator of depression-like behaviours and spatial cognitive deficits in mice subjected to CRS. Blockade of NOX2 signalling may be a promising therapeutic strategy for depression.

Hippocampal GPR35 is involved in the depression-like behaviors induced by inflammation and mediates the antidepressant effects of fluoxetine in mice

BACKGROUND

Neuroinflammation plays a pivotal role in the pathogenesis of depression. G protein-coupled receptor 35 (GPR35) is expressed in the brain and plays a role in regulating inflammatory processes. However, its specific role in depression remains unclear. Herein, we investigate the role of GPR35 in depressive behaviors induced by lipopolysaccharide (LPS) in mice.

METHODS

We employed an LPS-induced depression mouse model and conducted behavioral tests, molecular analyses, and morphological assessments, along with chemogenetic techniques, to investigate the role of GPR35 in depression.

RESULTS

Our results showed a significant increase in GPR35 expression in the brain of LPS-treated mice. Both pharmacological inhibition and genetic knockdown of GPR35 alleviated LPS-induced depressive-like behaviors by mitigating neuroinflammation, oxidative stress, synaptic plasticity deficits, and TLR4/NF-κB signaling in mice. Conversely, pharmacological activation of GPR35 notably exacerbated LPS-induced depressive-like behaviors in mice. Additionally, the GPR35 antagonist ML-145 effectively prevented LPS-induced inflammation responses in BV-2 microglia cells. Moreover, fluoxetine treatment effectively mitigated the upregulation of hippocampal GPR35 expression induced by LPS in mice. However, administration of the GPR35 agonist zaprinast reversed the antidepressant effects of fluoxetine. Chemogenetic activation of hippocampal glutamatergic neurons attenuated LPS-induced depression-like behaviors, accompanied by decreased GPR35 expression.

CONCLUSION

Hippocampal GPR35 is closely associated with depressive behaviors in the inflammatory model, highlighting its potential as a therapeutic target for antidepressant drug development.

BDNF mediates the heart-brain axis: implications for cardiovascular diseases and mental disorders

The comorbidity of cardiovascular diseases (CVDs) and mental disorders (MD) has become a significant challenge in modern medicine, severely affecting patients' quality of life and prognosis. The heart-brain axis, a bidirectional pathway connecting the central nervous system and the cardiovascular system, plays a critical role in the comorbidity mechanisms of CVDs and MD. In recent years, brain-derived neurotrophic factor (BDNF) has emerged as a key molecule in the study of CVDs and MD. By binding with high affinity to TrkB receptors and activating various signaling pathways, BDNF exerts multiple functions in both the nervous and cardiovascular systems. BDNF may participate in the pathogenesis of CVDs combined with MD through multiple mechanisms such as regulating inflammatory responses, oxidative stress (OS), and the hypothalamic-pituitary-adrenal (HPA) axis, making it a promising new target for future diagnosis and treatment. This review systematically summarizes the mechanisms by which BDNF functions in heart-brain comorbidity, particularly its multifaceted influence on inflammation, OS, and neuroendocrine regulation. Additionally, we discuss the clinical application prospects of BDNF in disease diagnosis and treatment, as well as progress in related drug development. A deeper understanding of BDNF's role in the heart-brain axis will provide new insights and strategies for the prevention, diagnosis, and treatment of CVDs and MD.

Probiotic Bactolac alleviates depression-like behaviors by modulating BDNF, NLRP3 and MC4R levels, reducing neuroinflammation and promoting neural repair in rat model

Depression, a prevalent psychiatric disorder, exerts severe and debilitating impacts on an individual's mental and physical well-being, and it is considered a chronic mental illness. Chronic stress plays an important role in the pathophysiology of depression. Lactobacillus plantarum and Streptococcus thermophilus are psychobiotic bacteria and synthesize some neurotransmitters that play a role in the pathogenesis of depression. In this study, we aimed to investigate the therapeutic effects of Bactolac (Lactobacillus plantarum NBIMCC 8767  + Streptococcus thermophilus NBIMCC 8258) on chronic stress-induced depression in rats. Behavioral tests, including the sucrose preference test, elevated plus maze test, forced swim test, and three-chamber sociability test, were employed to assess depressive and anxiety-like behaviors. The expression level of the 5-HT1A, DRD1, ADRA-2A, GABA-A α1, CNR1, NR3C2, NOD1, NLRP3 and MC4R; BDNF levels, glial activity and intestinal permeability were determined in chronic stress-induced depression in rats. In conclusions, chronic stress decreased the expression levels of 5-HT1A, DRD1, ADRA-2A, GABA-A α1, CNR1, NR3C2, NOD1 and BDNF level; increased the expression levels of NLRP3 and MC4R, caused neurodegeneration and glial activity, ultimately led to depressive effects. Bactolac was effective in reducing depressive-like behaviors according to the results of behavioral tests. Bactolac treatment provided high neuronal survival rate increasing BDNF level, prevented the excessive release of pro-inflammatory cytokines by reducing the expression levels of NLRP3 and MC4R, therefore, prevented the excessive activation of the hypothalamus-pituitary-adrenal (HPA) axis and accordingly, reduced neurodegeneration and glial cell activation in depressed rats. We can suggest that Bactolac supplementation may be beneficial in coping with stress, alleviate the effects of chronic stress and help to protect mental health.

The neuroplastic brain: current breakthroughs and emerging frontiers

Neuroplasticity, the brain's capacity to reorganize itself by forming new neural connections, is central to modern neuroscience. Once believed to occur only during early development, research now shows that plasticity continues throughout the lifespan, supporting learning, memory, and recovery from injury or disease. Substantial progress has been made in understanding the mechanisms underlying neuroplasticity and their therapeutic applications. This overview article examines synaptic plasticity, structural remodeling, neurogenesis, and functional reorganization, highlighting both adaptive (beneficial) and maladaptive (harmful) processes across different life stages. Recent strategies to harness neuroplasticity, ranging from pharmacological agents and lifestyle interventions to cutting-edge technologies like brain-computer interfaces (BCIs) and targeted neuromodulation are evaluated in light of current empirical evidence. Contradictory findings in the literature are addressed, and methodological limitations that hamper widespread clinical adoption are discussed. The ethical and societal implications of deploying novel neuroplasticity-based interventions, including issues of equitable access, data privacy, and the blurred line between treatment and enhancement, are then explored in a structured manner. By integrating mechanistic insights, empirical data, and ethical considerations, the aim is to provide a comprehensive and balanced perspective for researchers, clinicians, and policymakers working to optimize brain health across diverse populations.

Advances in discerning the mechanisms underlying depression and resiliency: relation to the neurobiology of stress and the effects of antidepressants

Depression denotes a dysregulated stress response with significant mental and health implications. This review examines the neurobiological mechanisms underlying depression and resilience, focusing on how stress mediators influence vulnerability to severe stressors contrasted with resilience. We analyze structural and functional alterations in key brain regions, genetic factors, and potential therapeutic interventions. Understanding these mechanisms offers insights into preventing depression onset instead of solely treating its manifestations.

Lack of relationships between ketamine treatment and peripheral neurotrophic and inflammatory factors in a randomized controlled ketamine trial of major depressive disorder

BACKGROUND

Ketamine is a rapid-acting treatment for treatment-resistant depression (TRD), though mechanisms related to ketamine's effects remain unclear. Blood-based neurotrophic and inflammatory factors (NIFs; e.g., brain-derived neurotrophic factor, interleukin-6) have emerged as markers potentially linked to ketamine and ketamine treatment response.

METHODS

In this secondary analysis of a randomized controlled trial (RCT), 133 adults with TRD received a single-dose infusion of ketamine (n = 89; 0.5 mg/kg) or saline (n = 44) and provided measures of peripheral blood NIF levels and depression severity across a five-day post-infusion period. Differences between ketamine and saline groups were examined for (1) NIF levels, (2) associations between NIF trajectories and depression score trajectories, and (3) associations between baseline NIF levels and depression score trajectories. Subgroup sensitivity analyses examined identical relationships within many (n = 28) discrete subgroups of individuals.

RESULTS

No differences were found between ketamine and saline cohorts for NIF trajectories, associations of NIF and depression trajectories, or associations of baseline NIF levels and depression trajectories. On subgroup analyses, in participants with lower BMI (BMI < 25; n = 66), increasing interleukin-1 receptor antagonist (IL-1RA) trajectories post-ketamine were associated with less improvement in depression in the first day post-infusion.

DISCUSSION

Associations between ketamine treatment and peripheral neurotrophic/inflammatory factors were not detected in our RCT of 133 adults with TRD. The sole exception across exhaustive sensitivity analyses was that, in individuals with low BMI, increases in IL-1RA levels may be linked to worse immediate treatment response. Future research investigating CNS-specific NIF activity is needed to more definitively test the posited role of NIFs in ketamine's antidepressant mechanisms.

Effects of Probiotics as Adjunctive Therapy to Fluoxetine on Depression Severity and Serum Brain-Derived Neurotrophic Factor, Cortisol, and Adrenocorticotropic Hormone in Patients With Major Depressive Disorder: A Randomized, Double-Blind, Placebo-Controlled Trial

Probiotics may improve mood, but their role as adjunctive therapy for major depressive disorder (MDD) is not well understood. This study examines the effects of probiotics on depression severity, brain-derived neurotrophic factor (BDNF), adrenocorticotropic hormone (ACTH), and cortisol levels in MDD patients. Fifty medication-free MDD patients were randomized to receive probiotics with fluoxetine (n = 25) or placebo with fluoxetine (n = 25) for 8 weeks. Depression severity was assessed using the Hamilton Depression Rating Scale (HDRS-24), and fasting blood samples were collected at baseline and study conclusion. Forty-four patients completed the trial. The probiotic group showed a significant reduction in depression severity compared with the placebo group (p = 0.001). No significant differences were observed in serum cortisol (p = 0.46) and ACTH levels (p = 0.44). Plasma BDNF levels increased slightly in the probiotic group but were not statistically significant. Probiotic supplementation with fluoxetine significantly reduces depression severity in MDD patients.

Examining a role for irisin in treating cerebral ischemia

Stroke is a leading cause of death and disability, with ischemic stroke representing most cases. Age is the most significant nonmodifiable risk factor for stroke, and with an aging population, there is an urgent need for effective prevention and treatment strategies. Physical inactivity is a strong risk factor for stroke, and exercise has long been held as a promising approach to improve poststroke outcomes. During exercise, the myokine irisin is released as a product of a type 1 membrane protein cleavage that is encoded by the fibronectin type III domain containing 5 (FNDC5) gene. This review summarizes recent literature on irisin's role in ischemic stroke, examining central effects, stroke risk, poststroke functional outcomes, and exogenous administration. Irisin has value as a prognostic marker for risk stratification. Low levels of irisin correlate with worse outcomes and higher mortality in patients with ischemic stroke. Irisin may also be a key to the benefits of exercise, particularly for high-intensity resistance training, which significantly increases irisin levels. Beyond exercise, exogenous irisin is neuroprotective in murine models, reducing brain edema, inflammation, and apoptosis, and increasing blood-brain barrier integrity and brain-derived neurotrophic factor levels. This underscores irisin's potential to mitigate ischemic damage and promote recovery. Human trials are necessary to validate these findings and explore the feasibility of irisin-based interventions in acute stroke care. This review lays a foundation for future research to clarify irisin's therapeutic benefits, establish optimal exercise protocols, and explore exogenous irisin as a novel intervention for ischemic stroke.

Pharmacologically activating BDNF/TrkB signaling exerted rapid-acting antidepressant-like effects through improving synaptic plasticity and neuroinflammation

BDNF (Brain-derived neurotrophic factor)/TrkB (tropomyosin receptor kinase B) signaling has great therapeutic potential for depression, but the underlying mechanism remains unclear. This study aims to investigate the molecular mechanism underlying the BDNF/TrkB signaling-mediated antidepressant effects. Chronic Cort drinking for 4 weeks and a single injection of LPS for 24 h were used to induce depression-like behaviors; this study used 7,8-dihydroxyflavone (7,8-DHF, 10 mg/kg, i.p.), a selective TrkB receptor agonist, to activate the BDNF/TrkB signaling and examined its rapid-acting antidepressant-like effects; levels of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) in BV2 microglial cells and synapse-related factors (BDNF, GluA1, Synapsin-1, and PSD95) in HT22 cells were examined by ELISA. Our behavioral results suggested that 7,8-DHF (10 mg/kg, i.p.) exerted rapid-acting antidepressant-like effects in Cort/LPS-treated mice; our immunofluorescence staining results suggested that Cort/LPS reduced the number of NeuN + HT22 cells and increased the number of Iba1 + BV2 microglial cells, which were completely reversed by 7,8-DHF pre-treatment. Our ELISA results suggested that 7,8-DHF significantly normalized the release of synapse-related factors (BDNF, GluA1, and PSD95) in HT22 cells and suppressed the production of inflammatory cytokines (IL-1β, IL-6, and TNF-α) in BV2 microglial cells. Taken together, this study suggested that pharmacologically activating the BDNF/TrkB signaling pathway exerted rapid-acting antidepressant-like effects through improving synaptic plasticity and inhibiting neuroinflammation, which provided new insights for developing next-generation rapid-acting antidepressants.

The Restoration of Energy Pathways Indicates the Efficacy of Ketamine Treatment in Depression: A Metabolomic Analysis

AIMS

Despite the clinical benefits of ketamine in treating major depressive disorder (MDD), some patients exhibit drug resistance, and the intricate mechanisms underlying this await comprehensive explication. We used metabolomics to find biomarkers for ketamine efficacy and uncover its mechanisms of action.

METHODS

The study included 40 MDD patients treated with ketamine in the discovery cohort and 24 patients in the validation cohort. Serum samples from the discovery cohort receiving ketamine were analyzed using ultra performance liquid chromatography-mass spectrometry to study metabolomic changes and identify potential biomarkers. Metabolic alterations were evaluated pre- and post-ketamine treatment. Spearman correlation was applied to examine the relationship between metabolite alterations and depressive symptom changes. In addition, potential biomarkers, particularly thyroxine, were investigated through quantitative measurements in the validation cohort.

RESULTS

We found that energy metabolite changes (adenosine triphosphate, adenosine diphosphate [ADP], pyruvate) were different in responders versus non-responders. The magnitude of the ADP shift was strongly correlated with the rate of reduction in Montgomery-Asberg Depression Rating Scale (MADRS) scores (Rho = 0.48, pFDR = 0.018). Additionally, baseline free triiodothyronine (FT3) levels are inversely associated with the rate of MADRS reduction (Rho = -0.645, p = 0.017).

CONCLUSIONS

Ketamine ameliorates depressive symptoms by modulating metabolic pathways linked to energy metabolism. Low baseline FT3 levels appear to predict a positive response in MDD patients, suggesting FT3 has potential as a biological marker for clinical ketamine treatment.

TRIAL REGISTRATION

ChiCTR-OOC-17012239.

Multimodal insights into adult neurogenesis: An integrative review of multi-omics approaches

Adult neural stem cells divide to produce neurons that migrate to preexisting neuronal circuits in a process named adult neurogenesis. Adult neurogenesis is one of the most exciting areas of current neuroscience, and it may be involved in a range of brain functions, including cognition, learning, memory, and social and behavior changes. While there is a growing number of multi-omics studies on adult neurogenesis, generalized analyses from a multi-omics perspective are lacking. In this review, we summarize studies related to genomics, metabolomics, proteomics, epigenomics, transcriptomics, and microbiomics of adult neurogenesis, and then discuss their future research priorities and potential neighborhoods. This will provide theoretical guidance and new directions for future research on adult neurogenesis.

Non-pharmacological therapeutic paradigms in stress-induced depression: from novel therapeutic perspective with focus on cell-based strategies

Major depressive disorder (MDD) is considered a psychiatric disorder and have a relationship with stressful events. Although the common therapeutic approaches against MDD are diverse, a large number of patients do not present an adequate response to antidepressant treatments. On the other hand, effective non-pharmacological treatments for MDD and their tolerability are addressed. Several affective treatments for MDD are used but non-pharmacological strategies for decreasing the common depression-related drugs side effects have been focused recently. However, the potential of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs), microRNAs (miRNAs) as cell-based therapeutic paradigms, besides other non-pharmacological strategies including mitochondrial transfer, plasma, transcranial direct current stimulation (tDCS), transcranial magnetic stimulation (TMS), and exercise therapy needs to further study. This review explores the therapeutic potential of cell-based therapeutic non-pharmacological paradigms for MDD treatment. In addition, plasma therapy, mitotherapy, and exercise therapy in several in vitro and in vivo conditions in experimental disease models along with tDCS and TMS will be discussed as novel non-pharmacological promising therapeutic approaches.

Quinoa Ethanol Extract Ameliorates Cognitive Impairments Induced by Hypoxia in Mice: Insights into Antioxidant Defense and Gut Microbiome Modulation

Quinoa, rich in pharmacologically active ingredients, possesses the potential benefit in preventing cognitive impairments induced by hypoxia. In this study, the efficacy of quinoa ethanol extracts (QEE) consumption (200 and 500 mg/kg/d, respectively) against hypobaric hypoxia (HH)-induced cognitive deficits in mice was investigated. QEE significantly ameliorated hypoxic stress induced by HH, as evidenced by improvements in baseline indices and reductions in hypoxia-inducible factor 1α levels. Furthermore, QEE enhanced antioxidant defense mechanisms, alleviated neuroinflammation in brain regions associated with memory, and improved HH-induced cognitive impairments by modulating the cyclic adenosine monophosphate response element-binding protein/brain-derived neurotrophic factor signaling pathway. Higher doses generally yielded more effective outcomes than lower doses. QEE also significantly reshaped the gut microbiome structure of HH mice, inhibited gut barrier damage, and reduced lipopolysaccharide migration, thereby increasing short-chain fatty acids (SCFAs) levels. Our findings suggest that QEE may be a promising strategy for preventing hypoxia-induced cognitive impairments by maintaining gut microbiome stability and increasing SCFAs levels.

Safety in treatment: Classical pharmacotherapeutics and new avenues for addressing maternal depression and anxiety during pregnancy

We aimed to review clinical research on the safety profiles of antidepressant drugs and associations with maternal depression and neonatal outcomes. We focused on neuroendocrine changes during pregnancy and their effects on antidepressant pharmacokinetics. Pregnancy-induced alterations in drug disposition and metabolism impacting mothers and their fetuses are discussed. We considered evidence for the risks of antidepressant use during pregnancy. Teratogenicity associated with ongoing treatment, new prescriptions during pregnancy, or pausing medication while pregnant was examined. The Food and Drug Administration advises caution regarding prenatal exposure to most drugs, including antidepressants, largely owing to a dearth of safety studies caused by the common exclusion of pregnant individuals in clinical trials. We contrasted findings on antidepressant use with the lack of treatment where detrimental effects to mothers and children are well researched. Overall, drug classes such as selective serotonin reuptake inhibitors and serotonin norepinephrine reuptake inhibitors appear to have limited adverse effects on fetal health and child development. In the face of an increasing prevalence of major mood and anxiety disorders, we assert that individuals should be counseled before and during pregnancy about the risks and benefits of antidepressant treatment given that withholding treatment has possible negative outcomes. Moreover, newer therapeutics, such as ketamine and κ-opioid receptor antagonists, warrant further investigation for use during pregnancy. SIGNIFICANCE STATEMENT: The safety of antidepressant use during pregnancy remains controversial owing to an incomplete understanding of how drug exposure affects fetal development, brain maturation, and behavior in offspring. This leaves pregnant people especially vulnerable, as pregnancy can be a highly stressful experience for many individuals, with stress being the biggest known risk factor for developing a mood or anxiety disorder. This review focuses on perinatal pharmacotherapy for treating mood and anxiety disorders, highlighting the current knowledge and gaps in our understanding of consequences of treatment.

Association of the Val66Met Polymorphism of the BDNF Gene with the Depression in a Mexican Population with Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, autoimmune pathology that affects the nervous system. It is characterized by inflammatory lesions that cause axonal damage with neurodegeneration. The signs and symptoms present in this pathology include among others, psychiatric disorders. In MS, depression is the most frequent psychiatric disorder, with prevalence levels of 40 to 60%; to date, the cause is unknown. The brain-derived neurotrophic factor (BDNF) is a neurotrophin related to neuroplasticity. The single-nucleotide polymorphism Val66Met, encoded by the BDNF gene, has been associated with various effects, including the presence of neuropsychiatric disorders. The purpose of our study was to evaluate the association between the BDNF Val66Met polymorphism and depression in MS patients.

METHODS

Study design, cases, and controls: Mexican mestizo MS patients.

CASES

Patients diagnosed with depression.

CONTROLS

Patients without depression diagnosis.

MEASUREMENTS

For depression, the Beck Depression Inventory; for polymorphism, real-time PCR.

RESULTS

No statistically significant differences were found in sociodemographic and disease variables between the case and control groups. qPCR analysis showed that 68% of the participants were Val/Val wild-type homozygotes, 29% were Val/Met polymorphism heterozygotes, and 3% were Met/Met polymorphism homozygotes. The presence of the BDNF gene rs6265 polymorphism was associated with a 5.6-fold increase in the probability of depression in the cases compared to the controls.

CONCLUSIONS

The BDNF Val66Met Polymorphism is associated with depression in Mexican mestizo patients diagnosed with MS.

Demystifying the Antidepressant Mechanism of Action of Stinels, a Novel Class of Neuroplastogens: Positive Allosteric Modulators of the NMDA Receptor

Plastogens are a class of therapeutics that function by rapidly promoting changes in neuroplasticity. A notable example, ketamine, is receiving great attention due to its combined rapid and long-term antidepressant effects. Ketamine is an N-methyl-D-aspartate receptor (NMDAR) antagonist, and, in addition to its therapeutic activity, it is associated with psychotomimetic and dissociative side effects. Stinels-rapastinel, apimostinel, and zelquistinel-are also plastogens not only with rapid and long-term antidepressant effects but also with improved safety and tolerability profiles compared to ketamine. Previous descriptions of the mechanism by which stinels modulate NMDAR activity have been inconsistent and, at times, contradictory. The purpose of this review is to clarify the mechanism of action and contextualize stinels within a broader class of NMDAR-targeting therapeutics. In this review, we present the rationale behind targeting NMDARs for treatment-resistant depression and other psychiatric conditions, describe the various mechanisms by which NMDAR activity is regulated by different classes of therapeutics, and present evidence for the stinel mechanism. In contrast with previous descriptions of glycine-like NMDAR partial agonists, we define stinels as positive allosteric modulators of NMDAR activity with a novel regulatory binding site.

Neurological mechanism-based analysis of the role and characteristics of physical activity in the improvement of depressive symptoms

Depression is a common mental disorder characterized by a high prevalence and significant adverse effects, making the searching for effective interventions an urgent priority. In recent years, physical activity (PA) has increasingly been recognized as a standard adjunctive treatment for mental disorders owing to its low cost, easy application, and high efficiency. Epidemiological data shows positive preventive and therapeutic effects of PA on mental illnesses such as depression. This article systematically describes the prophylactic and therapeutic effects of PA on depression and its biological basis. A comprehensive literature analysis reveals that PA significantly improves depressive symptoms by upregulating the expression of "exerkines" such as irisin, adiponectin, and BDNF to positively impacting neuropsychiatric conditions. In particular, lactate could also play a critical role in the ameliorating effects of PA on depression due to the findings about protein lactylation as a novel protein post-transcriptional modification. The literature also suggests that in terms of brain structure, PA may improve hippocampal volume, basal ganglia (neostriatum, caudate-crustal nucleus) and PFC density in patients with MDD. In summary, this study elucidates the multifaceted positive effects of PA on depression and its potential biological mechanisms with a particular emphasis on the roles of various exerkines. Future research may further investigate the effects of different types, intensities, and durations of PA on depression, as well as how to better integrate PA interventions into existing treatment strategies to achieve optimal outcomes in mental health interventions.

Exploring the association between BDNF related signaling pathways and depression: A literature review

Depression is a debilitating mental disease that inflicts significant harm upon individuals and society, yet effective treatment options remain elusive. At present, the pathogenesis of multiple depression is not fully clear, but its occurrence can be related to biological or environmental pathways, among which Brain-derived neurotrophic factor (BDNF) can unequivocally act on two downstream receptors, tyrosine kinase receptor (TrkB) and the p75 neurotrophin receptor (p75NTR), then affect the related signal pathways, affecting the occurrence and development of depression. Accumulating studies have revealed that BDNF-related pathways are critical in the pathophysiology of depression, and their interaction can further influence the efficacy of depression treatment. In this review, we mainly summarized the signaling pathways associated with BDNF and classified them according to different receptors and related molecules, providing promising insights and future directions in the treatment of depression.

Effect of Withania somnifera on Expression of Selected Genes in Hippocampus of Male Wistar Rats Subjected to Chronic Unpredictable Mild Stress

Background

Depression affects millions globally, with existing treatments having many side effects. Withania somnifera (WS) shows potential as an antidepressant and neuroprotective agent, possibly by influencing brain-derived neurotrophic factor (BDNF)-related pathways.

Aim

This study evaluated the effect of WS alone and in combination with fluoxetine on neuritin, NARP, and BDNF Exon-III gene expression in the hippocampus of male Wistar rats subjected to chronic unpredictable mild stress (CUMS).

Materials and Methods

Thirty male Wistar rats were divided into five groups (n = 6 each): normal group (NG), disease control (DC), standard treatment (ST), WS, and combination group of fluoxetine and WS (FW). Depression was induced using CUMS, except in the NG. The sucrose preference test confirmed depression at the end of 3rd week and assessed treatment effects at the end of 7th week. Gene expression in the hippocampus was analyzed through real-time PCR at the end of 7th week.

Results

After 7 weeks, the ST, WS, and FW groups showed a significant increase in sucrose preference compared to the DC group. The ST and FW groups showed significant upregulation of all three genes selected in the present study. Comparison between NG and FW groups showed no significant difference in gene expression.

Conclusion

This study highlights the antidepressant effects of WS by demonstrating its effect on BDNF-associated gene expression. Fluoxetine combined with WS demonstrated additive effects which proves an adjuvant role of WS in the treatment of depression. Further studies involving human subjects are essential to validate the antidepressant effects of WS and its additive effects with fluoxetine.

Activation of 5-HT6 Receptors in the Ventrolateral Orbital Cortex Produces Anti-Anxiodepressive Effects in a Rat Model of Neuropathic Pain

The comorbidity of anxiety and depression frequently occurs in patients with neuropathic pain. The ventrolateral orbital cortex (VLO) plays a critical role in mediating neuropathic pain and anxiodepression in rodents. Previous studies suggested that 5-HT6 receptors in the VLO are involved in neuropathic pain. Strong evidence supports a close link between 5-HT6 receptors and affective disorders such as depression and anxiety disorders. However, it remains unclear whether the 5-HT6 receptors in the VLO are involved in neuropathic pain-induced anxiodepression. Using a rat neuropathic pain model of spared nerve injury (SNI), we demonstrated that rats exhibited significant anxiodepression-like behaviors and the expression of VLO 5-HT6 receptors obviously decreased four weeks after SNI surgery. Microinjection of the 5-HT6 receptor agonist EMD-386088 into the VLO or overexpression of VLO 5-HT6 receptors alleviated anxiodepression-like behaviors. These effects were blocked by pre-microinjection of a selective 5-HT6 receptor antagonist (SB-258585) or inhibitors of AC (SQ-22536), PKA (H89), and MEK1/2 (U0126) respectively. Meanwhile, the expression of p-ERK, p-CREB, and BDNF in the VLO decreased four weeks after SNI surgery. Furthermore, administration of EMD-386088 upregulated the expression of BDNF, p-ERK, and p-CREB in the VLO of SNI rats, which were reversed by pre-injection of SB-258585. These findings suggest that activating 5-HT6 receptors in the VLO has anti-anxiodepressive effects in rats with neuropathic pain via activating AC-cAMP-PKA-MERK-CREB-BDNF signaling pathway. Accordingly, 5-HT6 receptor in the VLO could be a potential target for the treatment of the comorbidity of neuropathic pain and anxiodepression.

Protective effects of exercise on responses to combined social and environmental stress in prairie voles

The combination of social and environmental stressors significantly influences psychological and physical health in males and females, and contributes to both depression and cardiovascular diseases. Animal models support these findings. Voluntary exercise may protect against some forms of stress; however, the protective effects of exercise against social stressors require further investigation. This study evaluated the influence of exercise on the impact of combined social and environmental stressors in socially monogamous prairie voles. Following a period of social isolation plus additional chronic environmental stress, prairie voles were either allowed access to a running wheel in a larger cage for 2 weeks or remained in sedentary conditions. A behavioral stress task was conducted prior to and following exercise or sedentary conditions. Heart rate (HR) and HR variability were evaluated after exercise or sedentary conditions. Group-based analyses indicated that exercise prevented elevated resting HR and promoted autonomic control of the heart. Exercise was also effective against social and environmental stress-induced forced swim test immobility. Some minor sex differences in behavior were observed in response to exercise intensity. This research informs our understanding of the protective influence of physical exercise against social and environmental stressors in male and female humans.

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

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

The Optimal Type and Dose of Exercise for Elevating Brain-Derived Neurotrophic Factor Levels in Patients With Depression: A Systematic Review With Pairwise, Network, and Dose-Response Meta-Analyses

Background: Reduced brain-derived neurotrophic factor (BDNF) levels have been linked to increased depression risk. While physical exercise is known to alleviate depressive symptoms and elevate BDNF levels, the effects of different exercise modalities and doses, along with their dose-response relationships, remain unclear. Objective: This study aims to systematically evaluate the effects of various exercise types and doses on BDNF levels in patients with depression through pairwise meta-analysis, network meta-analysis (NMA), and dose-response NMA and to provide personalized exercise prescription recommendations. Methods: A comprehensive search identified randomized controlled trials (RCTs) examining exercise's impact on BDNF levels in depression. Pairwise and NMA compared six exercise modalities: continuous aerobic exercise (CAE), resistance exercise (RE), combined aerobic and resistance exercise (AERE), yoga, Qigong, and mindfulness. Dose-response NMA was used to assess the relationships between exercise dose and BDNF levels. Results: Thirty-six RCTs with 2515 participants were included. The pairwise meta-analysis indicated that all exercise interventions significantly elevated BDNF levels in patients with depression, with AERE, RE, and yoga demonstrating the most substantial effects. NMA rankings suggested that AERE was the most effective intervention, followed by RE, yoga, Qigong, mindfulness, and CAE. Dose-response NMA revealed a positive nonlinear dose-response relationship between total exercise volume and BDNF levels, with an optimal effective dose identified at ~610 METs-min/week. Beyond 1000 metabolic equivalent of tasks (METs)-min/week, increases in BDNF levels appeared to plateau. Moreover, each exercise type had distinct dose-response patterns, with RE and AERE having relatively higher optimal effective dose ranges, while CAE, yoga, Qigong, and mindfulness exhibited lower optimal ranges. Conclusions: AERE, RE, and yoga are effective interventions for enhancing BDNF levels in patients with depression, with Qigong, mindfulness, and CAE being comparatively less effective. A positive nonlinear dose-response relationship between exercise volume and BDNF levels was observed. Further research is needed to refine dose-response relationships in this population.

H2S improves hippocampal synaptic plasticity in SPS rats via PI3K/AKT signaling pathway

Post-traumatic stress disorder (PTSD) is a severe mental illness that could impose heavy burdens on individuals and society, but effective and precise treatment modalities are unknown. The level of hydrogen sulfide (H2S) in the brain plays an important role in psychiatric diseases. However, it is still unclear whether PTSD exposure could affect the level of H2S and whether there is a correlation between H2S levels and the pathogenesis of PTSD. In this study, we selected single prolonged stress (SPS) as a PTSD model and found that SPS exposure decreased the endogenous H2S content accompanied by abnormal behavioral changes and dysregulation of the hippocampal synaptic plasticity in SPS rats. We further found that the exogenous administration of H2S could alleviate PTSD-like behaviors and improve hippocampal synaptic plasticity in SPS rats. In addition, we further used the phosphatidylinositol-3 kinase (PI3K) inhibitor LY294002 to interfere with the PI3K/AKT/BDNF signaling pathway. It was found that LY294002 significantly blocked the anti-anxiety effect and the improvement in synaptic plasticity derived from the exogenous administration of H2S in SPS rats. These results suggested that the endogenous H2S content was decreased in SPS rats, and that the exogenous administration of H2S could ameliorate abnormal disorders and improve hippocampal synaptic plasticity by mediating the PI3K/AKT pathway.

Antidepressant-like and antistress effects of the ACTH(4-10) synthetic analogs Semax and Melanotan II on male rats in a model of chronic unpredictable stress

Current antidepressant therapy shows substantial limitations, and there is an urgent need for the development of new treatment strategies for depression. Stressful events and hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis play an important role in the pathogenesis of depression. HPA axis activity is self-regulated by negative feedback at several levels including adrenocorticotropic hormone (ACTH)-mediated feedback. Here, we investigated whether noncorticotropic synthetic analogs of the ACTH(4-10) fragment, ACTH(4-7)-Pro-Gly-Pro (Semax) and Ac-Nle4-cyclo[Asp5-His6-D-Phe7-Arg8-Trp9-Lys10]ACTH(4-10)-NH2 (Melanotan II (MTII), a potent agonist of melanocortin receptors), have potential antidepressant activity in a chronic unpredictable stress (CUS) rat model of depression. Stressed and control male adult Sprague-Dawley rats received daily intraperitoneal injections of saline or a low dose (60 nmol/kg of body weight (BW)) of Semax or MTII. Rats were monitored for BW and hedonic status, as measured in the sucrose preference test. We found that chronic treatment with Semax and MTII reversed or substantially attenuated CUS-induced anhedonia, BW gain suppression, adrenal hypertrophy and a decrease in the hippocampal levels of BDNF. In the forced swim test, no effects of the CUS procedure or peptides on the duration of rat immobility were detected. Our findings show that in the CUS paradigm, systemically administered ACTH(4-10) analogs Semax and MTII exert antidepressant-like effects on anhedonia and hippocampal BDNF levels, and attenuate markers of chronic stress load, at least in male rats. The results support the argument that ACTH(4-10) analogs and other noncorticotropic melanocortins may have promising therapeutic potential for the treatment and prevention of depression and other stress-related pathologies.

Variations in BDNF and Their Role in the Neurotrophic Antidepressant Mechanisms of Ketamine and Esketamine: A Review

Brain-derived neurotrophic factor (BDNF) is critical for neuroplasticity, synaptic transmission, and neuronal survival. Studies have implicated it in the pathophysiology of depression, as its expression is significantly reduced in brain areas such as the prefrontal cortex and hippocampus in patients with depression. Our narrative review focuses on the relationship between BDNF, ketamine, and esketamine, specifically by summarizing human studies investigating BDNF variations in patients treated with these two drugs. BDNF plays a pivotal role in neuroplasticity and neurotrophic mechanisms that can be enhanced by traditional antidepressants, which have been shown to increase BDNF levels both peripherally and in targeted brain regions. Ketamine and its S-enantiomer, esketamine, exert both rapid and sustained antidepressant effects through activation of glutamate-related pathways, with neurotrophic effects involving BDNF, as demonstrated in experimental studies. However, clinical findings have shown mixed results, with most indicating an increase in plasma BDNF in patients treated with intravenous ketamine, although some studies contradict these findings. In addition to this, there are few studies of BDNF and esketamine. Currently, the limited number of studies suggests the need for further research, including larger sample sizes and investigations of BDNF and intranasal esketamine, which has been approved by several regulatory agencies for the treatment of treatment-resistant depression.

The Role of BDNF in the Antidepressant Effects of Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is an effective treatment method for depression therapy. It produces a number of biological effects, including neurotrophic factors regulation. In the present paper, we investigated the ECT response in depressed rats subjected to the variable frequency ultrasound (20-45 kHz) and examined the contribution of brain-derived neurotrophic factor (BDNF) expression changes to the observed effects. The obtained results reflect the therapeutic potential of ECT for the treatment of depressive-like state in rodents and indicate the role of BDNF in these processes. In future research, it is necessary to investigate the relationship between neurotrophin and structural changes and to study other neurotrophic biomarkers that may be associated with the development of depression-like state and the therapy response.

The Compelling Role of Brain-Derived Neurotrophic Factor Signaling in Multiple Sclerosis: Role of BDNF Activators

Brain-derived neurotrophic factor (BDNF) is a neurotrophin, acting as a neurotrophic signal and neuromodulator in the central nervous system (CNS). BDNF is synthesized from its precursor proBDNF within the CNS and peripheral tissues. Through activation of NTRK2/TRKB (neurotrophic receptor tyrosine kinase 2), BDNF promotes neuronal survival, synaptic plasticity, and neuronal growth, whereas it inhibits microglial activation and the release of pro-inflammatory cytokines. BDNF is dysregulated in different neurodegenerative diseases and depressions. However, there is a major controversy concerning BDNF levels in the different stages of multiple sclerosis (MS). Therefore, this review discusses the potential role of BDNF signaling in stages of MS, and how BDNF modulators affect the pathogenesis and outcomes of this disease.

The pathophysiology of estrogen in perinatal depression: conceptual update

PURPOSE

Estrogen levels fall sharply after parturition and have long been considered an etiologic contributor to postpartum depression (PPD); however, no differences have been reported in plasma hormone concentrations in people who develop PPD. We examine the question: What is the current view of estrogen and the neurophysiologic processes it impacts in the development and treatment of PPD?

METHODS

A literature review of the role of estrogen on candidate hormonal and epigenetic systems in the peripartum period was performed, including landmark historical studies and recent publications on estrogen-related research. The authors reviewed these papers and participated in reaching consensus on a conceptual framework of estrogen activity within the complexity of pregnancy physiology to examine its potential role for driving novel interventions.

RESULTS

Estrogen fluctuations must be conceptualized in the context of multiple dramatic and interacting changes inherent in pregnancy and after birth, including progesterone, corticosteroids, inflammation, circadian biology and psychosocial challenges. Individuals who develop PPD have increased sensitivity to epigenetic alteration at estrogen-responsive genes, and these changes are highly predictive of PPD. An effective estrogen-based treatment for PPD has yet to be found, but interventions focused on associated inflammation and circadian rhythms are promising.

CONCLUSIONS

Our understanding of the biological basis of PPD, one of the most common morbidities of the perinatal period, is expanding beyond changes in gynecologic hormone concentrations to include their impact on other systems. This growing understanding of the many processes influencing PPD will allow for the development of novel prevention and treatment strategies.

Therapeutic potential and mechanisms of stem cells in major depressive disorder: a comprehensive review

Depression is a common affective disorder characterized by persistent low mood, diminished interest or pleasure in normally enjoyable activities, disturbances in sleep patterns, and suicidal ideation. Conventional treatments often yield unsatisfactory results and are associated with several adverse effects. However, emerging literature has highlighted the potential of stem cell (SC) transplantation as a promising avenue for treating depression owing to its favorable anti-inflammatory and neurotrophic properties. This review summarizes the therapeutic effects and underlying mechanisms associated with SC transplantation in depression, offering a conceptual framework for the future application of SCs in the clinical treatment of depression.

Semen Cuscutae flavonoids activated the cAMP-PKA-CREB-BDNF pathway and exerted an antidepressant effect in mice

Background

Semen Cuscutae flavonoids (SCFs) constitute a class of metabolites of Semen Cuscutae, a botanical drug that was recently found to have an anti-depression effect. This study aimed to evaluate the anti-depression effects of SCFs in chronic unpredictable mild stress (CUMS)-induced mice and to interrogate the underlying mechanisms.

Materials and methods

The CUMS mice were used for assessing the effects of SCFs treatments on depression. Mice were randomly divided into five groups. Four groups were subjected to the CUMS induction and concomitantly administered orally with either the vehicle or with a high-, medium-, and low-dose of SCFs, once per day for 4 weeks. One group was kept untreated as a control. The mice were then assessed for their statuses of a number of depression-related parameters, including body weight, food intake, sucrose preference test (SPT), open field test (OFT), tail suspension test (TST), and forced swim test (FST). In addition, a day after the completion of these tests, biopsies from the hippocampus were harvested and used to perform metabolomics by HPLC-MS/MS and to assess the levels of cAMP by ELISA and the levels of PKA, CREB, p-CREB, and BDNF by Western blot analyses.

Results

SCFs resulted in significant increases in both body weight and food intake and in the amelioration of the depressive-like behaviors in CUMS mice. A high-dose SCFs treatment led to significant alterations in 72 metabolites, of which 26 were identified as potential biomarkers for the SCFs treatment. These metabolites are associated with lipid, amino acid, and nucleotide metabolism. Among 26 metabolites, cAMP was positively correlated with body weight, SPT, OFT-total distance, and OFT-central residence time, while negatively correlated with immobility time in TST and FST, linking a change in cAMP with the SCFs treatment and the significant improvement in depressive symptoms in CUMS mice. Further analyses revealed that the levels of cAMP, PKA, CREB, p-CREB, and BDNF were reduced in the hippocampus of CUMS mice but were all increased following the SCFs treatments.

Conclusion

SCFs could ameliorate hippocampal metabolic disturbances and depressive behaviors and cause the activation of the cAMP-PKA-CREB-BDNF signaling pathway in the hippocampus of CUMS mice.

Fluoxetine Ameliorates Cognitive Deficits in High-Fat Diet Mice by Regulating BDNF Expression

High-fat diet (HFD) induced obesity is associated with depression-related behavioral and neurogenic changes and may lead to cognitive impairment. Fluoxetine (FXT), the most commonly used antidepressant, may alleviate depressive symptoms by increasing neurogenesis, but the potential efficacy of FXT for HFD-induced cognitive deficits is unclear. In this study, we established an obese HFD mouse model by feeding three-week-old male C57BL/6N mice with a chronic HFD for 18 weeks, then assessed adipose tissue morphology by magnetic resonance imaging and histopathology, assessed cognitive function by Morris water maze and novel object recognition tests, and detected DCX+ and BrdU+ expression in the hippocampal dentate gyrus (DG) region by immunofluorescence bioassay. Western blot detected brain-derived neurotrophic factor (BDNF) levels and CREB-BDNF pathway-related genes were assayed by Quantitative RT-PCR. The results of the study showed that HFD contributes to obesity and cognitive deficits, and more importantly, it also reduces BDNF expression and neurogenesis levels in the hippocampus. Subsequently, we found that treatment with FXT (10 mg/kg/day) ameliorated chronic HFD-induced cognitive deficits and increased the expression of Nestin, BrdU+, and DCX+ in the DG, restored BDNF expression in the hippocampus and increased the expression of genes related to CREB, BDNF, NGF, and MAPK1. In conclusion, our data elucidated that FXT ameliorates cognitive deficits and reduces chronic HFD-induced neurogenesis by restoring BDNF expression and CREB-BDNF signaling, this provides a good basis and scientific significance for future research on the clinical treatment of obesity.

Brain-derived neurotrophic factor levels in perinatal depression: A systematic review and meta-analysis

BACKGROUND

This systematic review and meta-analysis aim to synthesize the available evidence and determine the overall brain-derived neurotrophic factor (BDNF) levels in individuals diagnosed with perinatal depression (PND).

METHODS

We performed a thorough search of electronic databases, including PubMed, Embase, PsycINFO, and Web of Science, from their start until April 30, 2023. Our search strategy involved using specific keywords and medical subject headings (MeSH) terms related to BDNF, perinatal, post-partum, and antepartum depression. In the meta-analysis, we employed a random-effects model, and subgroup analyses were conducted to investigate any variations in the results.

RESULTS

A total of 15 studies met the inclusion criteria, of which 10 were used in the quantitative analysis. The meta-analysis demonstrated a significant decrease in BDNF levels in both individuals with antepartum depression (SMD: -0.31; 95% CI: -0.48 to -0.13; p-value = 0.0008; I2 = 71%), and post-partum depression (SMD: -0.61; 95% CI: -0.99 to -0.22; p-value = 0.0002 I2 = 77%). Furthermore, a significantly higher rate of PND among individuals in the lowest BDNF quartile (OR: 2.64; 95% CI: 1.01 to 6.89; p-value = 0.05; I2 = 90%) was seen. The results of subgroup analyses showed a statistically significant effect of the depression assessment tool on overall heterogeneity between studies.

CONCLUSION

This systematic review and meta-analysis provide evidence of lower BDNF protein levels in individuals diagnosed with PND. The results indicate that BDNF dysregulation may play a part in the development of PND. More research is needed to understand the mechanisms behind this and explore potential therapeutic applications.

Microbiota-gut-brain axis: Natural antidepressants molecular mechanism

BACKGROUND

Major depressive disorder (MDD) is a severe mental health condition characterized by persistent depression, impaired cognition, and reduced activity. Increasing evidence suggests that gut microbiota (GM) imbalance is closely linked to the emergence and advancement of MDD, highlighting the potential significance of regulating the "Microbiota-Gut-Brain" (MGB) axis to impact the development of MDD. Natural products (NPs), characterized by broad biological activities, low toxicity, and multi-target characteristics, offer unique advantages in antidepressant treatment by regulating MGB axis.

PURPOSE

This review was aimed to explore the intricate relationship between the GM and the brain, as well as host responses, and investigated the mechanisms underlying the MGB axis in MDD development. It also explored the pharmacological mechanisms by which NPs modulate MGB axis to exert antidepressant effects and addressed current research limitations. Additionally, it proposed new strategies for future preclinical and clinical applications in the MDD domain.

METHODS

To study the effects and mechanism by which NPs exert antidepressant effects through mediating the MGB axis, data were collected from Web of Science, PubMed, ScienceDirect from initial establishment to March 2024. NPs were classified and summarized by their mechanisms of action.

RESULTS

NPs, such as flavonoids,alkaloids,polysaccharides,saponins, terpenoids, can treat MDD by regulating the MGB axis. Its mechanism includes balancing GM, regulating metabolites and neurotransmitters such as SCAFs, 5-HT, BDNF, inhibiting neuroinflammation, improving neural plasticity, and increasing neurogenesis.

CONCLUSIONS

NPs display good antidepressant effects, and have potential value for clinical application in the prevention and treatment of MDD by regulating the MGB axis. However, in-depth study of the mechanisms by which antidepressant medications affect MGB axis will also require considerable effort in clinical and preclinical research, which is essential for the development of effective antidepressant treatments.

Lindera aggregata improves intestinal function and alleviates depressive behaviors through the BDNF/TrkB/CREB signaling pathway induced by CUMS in mice

Depression is a common mental illness, which is highly related to intestinal motor dysfunction and causes a global burden of disease. Lindera aggregata (LA), a traditional medicinal herb, has been used to treat gastrointestinal disorders; however, the effect of LA on depression remains unclear. Here, we assessed the impact of LA on chronic unpredictable mild stress (CUMS)-induced depression in mice and explored the related mechanisms. The results showed that LA ameliorated depressive behaviors in mice exposed to CUMS, as evidenced by improved performance in the sucrose preference test, force swimming test, and open field test, as well as increased serum levels of adrenocorticotropic hormone and 5-hydroxytryptamine. In addition, LA increased the serum levels of D-xylose and ghrelin, indicating that LA can promote gastrointestinal motility. Additional studies revealed that LA relieved CUMS-induced hippocampal tissue damage, as shown by hematoxylin and eosin and Nissl staining. LA increased the expression levels of brain-derived neurotrophic factor (BDNF) and promoted the activation of tropomyosin receptor kinase B (TrkB) and cAMP response element-binding (CREB) in the hippocampus of CUMS-exposed mice or in corticosterone-injured HT22 cells. In conclusion, LA can improve CUMS-induced depressive behavior in mice, potentially through hippocampal neuroprotection mediated by the BDNF/TrkB/CREB signaling pathway, which also contributes to improved intestinal function.

Empagliflozin ameliorates olfactory bulbectomy-induced depression by mitigating oxidative stress and possible involvement of brain derived neurotrophic factor in diabetic rats

Empagliflozin, a sodium-glucose co-transporter 2 (SGLT2) inhibitor, has recently reported to prevent the depression in chronic animal model. The present study aimed to explore the antidepressant potential of empagliflozin using a neuroinflammation-mediated depression involving the olfactory bulbectomy (OBX) model in diabetic rats. A low dose of streptozotocin was injected to induce diabetes in all group of animals. Following the confirmation of hyperglycemia, OBX surgery was performed. Post-surgery, the drug treatments were administered orally for 14 consecutive days. The study evaluated the effects of daily oral administration of empagliflozin at doses of 5 and 10 mg/kg, alongside metformin (200 mg/kg) and clomipramine (50 mg/kg), on OBX-induced behavioral depression in rats. Separate sham and vehicle control groups were also maintained. Behavioral parameters in open field, forced swim test, elevated plus maze and splash test were recorded on 28th day. Results showed that empagliflozin, at the higher dose, significantly enhanced behavioral outcomes, evidenced by increased distance travelled, greater open arm entries, and reduced immobility, alongside a notable reduction in grooming time. Moreover, empagliflozin significantly restored the antioxidants level specifically Glutathione (GSH) and Catalase (CAT) in OBX insulted rat brain and decreased Lipid peroxidase (LPO). Notably, molecular docking study demonstrated a good binding affinity of empagliflozin for Brain-Derived Neurotrophic Factor (BDNF), suggesting that its antidepressant effects may be mediated through the modulation of the BDNF pathway. These findings support the potential therapeutic application of empagliflozin for depression, particularly in cases associated with neuroinflammation and oxidative stress.

Intranasal administration of recombinant human BDNF as a potential therapy for some primary headaches

BACKGROUND

In addition to its critical role in neurogenesis, brain-derived neurotrophic factor (BDNF) modulates pain and depressive behaviors.

METHODS

In a translational perspective, we tested the anti-migraine activity of highly purified and characterized recombinant human BDNF (rhBDNF) in an animal model of cephalic pain based on the chronic and intermittent NTG administration (five total injections over nine days), used to mimic recurrence of attacks over a given period. To achieve this, we assessed the effects of two doses of rhBDNF (40 and 80 µg/kg) administered intranasally to adult male Sprague-Dawley rats, on trigeminal hyperalgesia (by orofacial formalin test), gene expression (by rt-PCR) of neuropeptides and inflammatory cytokines in specific areas of the brain related to migraine pain. Serum levels of CGRP, PACAP, and VIP (by ELISA) were also evaluated. The effects of rhBDNF were compared with those of sumatriptan (5 mg/kg i.p), administered 1 h before the last NTG administration.

RESULTS

Both doses of rhBDNF significantly reduced NTG-induced nocifensive behavior in Phase II of the orofacial formalin test. The anti-hyperalgesic effect of intranasal high-dose rhBDNF administration in the NTG-treated animals was associated with a significant modulation of mRNA levels of neuropeptides (CGRP, PACAP, VIP) and cytokines (IL-1beta, IL-10) in the trigeminal ganglion, medulla-pons, and hypothalamic area. Of note, the effects of rhBNDF treatment were comparable to those induced by the administration of sumatriptan. rhBDNF administration at both doses significantly reduced serum levels of PACAP, while the higher dose also significantly reduced serum levels of VIP.

CONCLUSIONS

The findings suggest that intranasal rhBDNF has the potential to be a safe, non-invasive and effective therapeutic approach for the treatment of primary headache, particularly migraine.

The role of exercise-related FNDC5/irisin in depression

The complexity of depression presents a significant challenge to traditional treatment methods, such as medication and psychotherapy. Recent studies have shown that exercise can effectively reduce depressive symptoms, offering a new alternative for treating depression. However, some depressed patients are unable to engage in regular physical activity due to age, physical limitations, and other factors. Therefore, pharmacological agents that mimic the effects of exercise become a potential treatment option. A newly discovered myokine, irisin, which is produced during exercise via cleavage of its precursor protein fibronectin type III domain-containing protein 5 (FNDC5), plays a key role in regulating energy metabolism, promoting adipose tissue browning, and improving insulin resistance. Importantly, FNDC5 can promote neural stem cell differentiation, enhance neuroplasticity, and improve mood and cognitive function. This review systematically reviews the mechanisms of action of exercise in the treatment of depression, outlines the physiology of exercise-related irisin, explores possible mechanisms of irisin's antidepressant effects. The aim of this review is to encourage future research and clinical applications of irisin in the prevention and treatment of depression.

Fast-acting antidepressant-like effects of ketamine in aged male rats

BACKGROUND

The aging process causes anatomical and physiological changes that predispose to the development of late-life depression while reduces the efficacy of classical antidepressants. Novel fast-acting antidepressants such as ketamine might be good candidates to be explored in the context of aging, especially given the lack of previous research on its efficacy for this age period. Thus, the aim of the present study was to characterize ketamine's effects in older rats.

METHODS

The fast-acting (30 min) and repeated (7 days) antidepressant-like effects of ketamine (5 mg/kg, ip) were evaluated in 14-month-old single-housed rats through the forced-swim and novelty-suppressed feeding tests. In parallel, the modulation of neurotrophic-related proteins (i.e., mBDNF, mTOR, GSK3) was assessed in brain regions affected by the aging process, prefrontal cortex and hippocampus, as well as possible changes in hippocampal cell proliferation.

RESULTS

Acute ketamine induced a fast-acting antidepressant-like response in male aged rats, as observed by a reduced immobility in the forced-swim test, in parallel with a region-specific increase in mBDNF protein content in prefrontal cortex. However, repeated ketamine failed to induce antidepressant-like efficacy, but decreased mBDNF protein content in prefrontal cortex. The rate of hippocampal cell proliferation and/or other markers evaluated was not modulated by either paradigm of ketamine.

CONCLUSIONS

These results complement prior data supporting a fast-acting antidepressant-like effect of ketamine in rats, to further extend its efficacy to older ages. Future studies are needed to further clarify the lack of response after the repeated treatment as well as its potential adverse effects in aging.

Are BDNF and Stress Levels Related to Antidepressant Response?

Antidepressant response is a multifactorial process related to biological and environmental factors, where brain-derived neurotrophic factor (BDNF) may play an important role in modulating depressive and anxious symptoms. We aimed to analyze how BDNF impacts antidepressant response, considering the levels of anxiety.

METHODS

A total of 40 depressed adults were included. We evaluated initial serum BDNF, anxiety through the State-Trait Anxiety Inventory (STAI), and the severity of depressive symptoms by the Hamilton Depression Rating Scale (HDRS). Participants received antidepressant treatment for 8 weeks, and response to treatment was evaluated according to the final HDRS scores.

RESULTS

Basal BDNF was higher in responders compared to non-responder depressed patients, in addition to being inversely associated with the severity of anxiety and depression.

CONCLUSIONS

Baseline BDNF serum is an adequate predictive factor for response to antidepressant treatment with SSRI, with lower pre-treatment levels of BDNF associated with higher anxiety symptoms after treatment. Stress levels could influence the response to treatment, but its association was not conclusive.

Kappa Opioid Receptor Activation Induces Epigenetic Silencing of Brain-Derived Neurotropic Factor via HDAC5 in Depression

Treatment-resistant depression (TRD) occurs in almost 50% of the depressed patients. Central kappa opioid receptor (KOR) agonism has been demonstrated to induce depression and anxiety, while KOR antagonism alleviates depression-like symptoms in rodent models and TRD in clinical studies. Previously, we have shown that sustained KOR activation leads to a TRD-like phenotype in mice, and modulation of brain-derived neurotrophic factor (BDNF) expression in the prefrontal cortex (PFC) appears to be one of the molecular determinants of the antidepressant response. In the present study, we observed that sustained KOR activation by a selective agonist, U50488, selectively reduced the levels of Bdnf transcripts II, IV, and Bdnf CDS (protein-coding Exon IX) in the PFC and cultured primary cortical neurons, which was blocked by selective KOR antagonist, norbinaltorphimine. Considering the crucial role of epigenetic pathways in BDNF expression, we further investigated the role of various epigenetic markers in KOR-induced BDNF downregulation in mice. We observed that treatment with U50488 resulted in selective and specific downregulation of acetylation at the ninth lysine residue of the histone H3 protein (H3K9ac) and upregulation of histone deacetylase 5 (HDAC5) expression in the PFC. Further, using anti-H3K9ac and anti-HDAC5 antibodies in the chromatin immune precipitation assay, we detected decreased enrichment of H3K9ac and increased HDAC5 binding at Bdnf II and IV transcripts after U50488 treatment, which were blocked by a selective KOR antagonist, norbinaltorphimine. Further mechanistic studies using HDAC5 selective inhibitor, LMK235, in primary cortical neurons and adeno-associated viral shRNA-mediated HDAC5-knockdown in the PFC of mice demonstrated an essential role of HDAC5 in KOR-mediated reduction of Bdnf expression in the PFC and in depression-like symptoms in mice. These results suggest that KOR engages multiple pathways to induce depression-like symptoms in mice and provide novel insights into the mechanisms by which activation of KOR regulates major depressive disorders.

Proteomic characterization of the medial prefrontal cortex in chronic restraint stress mice

Depression is a prominent contributor to global disability. A growing body of data suggests that depression is associated with the pathophysiology of the medial prefrontal cortex (mPFC), but the underlying mechanisms remain poorly understood. Mice were subjected to chronic restraint stress (CRS) for 3 weeks to create depression models during this investigation. Protein tandem mass tag (TMT) quantification and LC-MS/MS analysis were conducted to examine proteome patterns. Afterwards, to further explore the enrichment of differential proteins and the signaling pathways involved, we annotated these differentially expressed proteins. We confirmed that CRS mice developed depression-like and anxiety-like behaviors. Among the 8081 measured proteins, a total of 15 proteins were found to be differentially expressed. These proteins exhibited functional enrichment in a variety of biological functions, and among these pathways, alterations in synaptic function and autophagy are noteworthy. In addition, we identified a differentially expressed protein called Wnt2b and found that CRS may disrupt synaptic plasticity by affecting the activation of the Wnt2b/β-catenin pathway. Our findings showed depression-like behaviors in the CRS mouse model and molecular alterations in the mPFC, which may help explain the pathogenesis of depression and identify novel antidepressant medication targets. SIGNIFICANCE: Depression is a prevalent and frequent chronic mental illness and is now a significant contributor to global disability. In this study, we used chronic restraint stress to establish a mouse model of depression, and differentially expressed proteins in the medial prefrontal cortex of depressed model mice were detected by TMT proteomics. Our study verified the presence of altered synaptic function and excessive autophagy in the mPFC of CRS-induced mice from a proteomic perspective. Furthermore, we demonstrated that CRS may disrupt synaptic plasticity by affecting the activation of the Wnt2b/β-catenin pathway, which may be a key link in the pathogenesis of depression and may provide new insights for identifying new antidepressant drug targets.

Serum brain derived neurotrophic factor levels and post-stroke depression in ischemic stroke patients

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is crucial for neuronal survival and may be implicated in the pathophysiological process of depression. This study aimed to prospectively investigate the association between serum BDNF and post-stroke depression (PSD) at 3 months in a multicenter cohort study.

METHODS

A total of 611 ischemic stroke patients with serum BDNF measurements from the China Antihypertensive Trial in Acute Ischemic Stroke were included in this analysis. We used the 24-item Hamilton Depression Rating Scale to assess depression status at 3 months after ischemic stroke, and PSD was defined as a score of ≥8.

RESULTS

Baseline serum BDNF was inversely associated with the risk of depression after ischemic stroke. The multivariable-adjusted odds ratio of PSD for the highest tertile of BDNF was 0.53 (95 % confidence interval, 0.34-0.82; P for trend = 0.004) compared with the lowest tertile. Multivariable-adjusted spline regression model also showed a linear does-response association between serum BDNF levels and PSD at 3 months (P for linearity = 0.006). In addition, adding serum BDNF to conventional risk factors significantly improved the risk reclassification of PSD (net reclassification improvement: 16.98 %, P = 0.039; integrated discrimination index: 0.93 %, P = 0.026).

LIMITATIONS

All patients in this study were Chinese, so our findings should be applied to other populations cautiously.

CONCLUSIONS

Higher serum BDNF levels at baseline were significantly associated with a decreased risk of PSD at 3 months, suggesting that BDNF might be a valuable predictive biomarker and potential therapeutic target for PSD among ischemic stroke patients.

Interaction effect of crocin and citalopram on memory and locomotor activity in rats: an insight into BDNF and synaptophysin levels in the hippocampus

Selective serotonin reuptake inhibitors (SSRIs) are widely used drugs for the treatment of depression. Citalopram is one of the most prescribed SSRIs that is useful for the treatment of depression, obsessive-compulsive disorder, and anxiety disorders. On the other hand, crocin (active constitute of saffron) has pro-cognitive and mood enhancer effects. Also, both citalopram and crocin affect the function and expression of brain-derived neurotrophic factor (BDNF) and synaptophysin, two molecular factors that are involved in cognitive functions and mood. In the present study, we aim to investigate the interaction effect of citalopram and crocin on rats' performance in the open field test (locomotor activity and anxiety-like behavior) and the shuttle box (passive avoidance memory). Citalopram was injected at the doses of 10, 30, and 50 mg/kg, and crocin was injected at the dose of 50 mg/kg; all administrations were intraperitoneal. Real-time PCR was used to assess the expression level of BDNF and synaptophysin in the hippocampus. The results showed that citalopram (30 and 50 mg/kg) impaired passive avoidance memory and decreased BDNF and synaptophysin expression in the hippocampus, while crocin reversed memory impairment, and BDNF and synaptophysin expression in the hippocampus of rats received citalopram 30 mg/kg. Also, crocin partially showed these effects in rats that received citalopram 50 mg/kg. The results of the open field test were unchanged. In conclusion, we suggested that BDNF and synaptophysin may be involved in the effects of both citalopram and crocin.

The role of BDNF transcription in the antidepressant-like effects of 18β-glycyrrhetinic acid in a chronic social defeat stress model

BACKGROUND

Xiaoyaosan (XYS), a traditional Chinese medicine formulation, has been used in the treatment of depression. However, no studies have yet identified the active compounds responsible for its antidepressant effects in the brain.

STUDY DESIGN

We investigated the antidepressants effects of XYS and identified 18β-glycyrrhetinic acid (18β-GA) as the primary compound present in the brain following XYS injection. Furthermore, we explored the molecular mechanisms underlying the antidepressant-like effects of both XYS and 18β-GA.

METHODS

To investigate the antidepressant-like effects of XYS and elucidate the associated molecular mechanisms, we employed various methodologies, including cell cultures, the chronic social defeat stress (CSDS) model, behavioral tests, immunoprecipitation, quantitative PCR (qPCR) assays, Western blotting assays, luciferase assays, chromatin immunoprecipitation (ChIP) assays, immunofluorescence staining, and dendritic spine analysis.

RESULTS

We identified 18β-GA as the primary compound in the brain following XYS injection. In vitro, 18β-GA was found to bind with ERK (extracellular signal-regulated kinase), subsequently activating ERK kinase activity toward both c-Jun and cAMP response element binding protein (CREB). Moreover, 18β-GA activated brain-derived neurotrophic factor (BDNF) transcription by stimulating nuclear factor-erythroid factor 2-related factor 2 (Nrf2), c-Jun, and CREB, while also inhibiting methyl CpG binding protein 2 (MeCP2) both in vitro and in vivo. Chronic intraperitoneal (i.p.) administration of 18β-GA exhibited prophylactic antidepressant-like effects in a CSDS model, primarily by activating BDNF transcription in the medial prefrontal cortex (mPFC). Interestingly, a single i.p. injection of 18β-GA produced rapid and sustained antidepressant-like effects in CSDS-susceptible mice by engaging the BDNF-tropomyosin receptor kinase B (TrkB) signaling pathway in the mPFC.

CONCLUSION

These findings suggest that the activation of BDNF transcription in the mPFC underlies the antidepressant-like effects of 18β-GA, a key component of XYS in the brain.