Role of calcium, glutamate and NMDA in major depression and therapeutic application

L-Cysteine: A promising nutritional supplement for alleviating anxiety disorders

Anxiety disorders are prevalent chronic psychological disease with complex pathogenic mechanisms. Current anxiolytics have limited efficacy and numerous side effects in many anxiety patients, highlighting the urgent need for new therapies. Recent research has been focusing on nutritional supplements, particularly amino acids, as potential therapies for anxiety disorders. Among these, L-Cysteine plays a crucial role in various biological processes. L-Cysteine exhibits antioxidant properties that can enhance the antioxidant functions of the central nervous system (CNS). Furthermore, metabolites of L-cysteine, such as glutathione and hydrogen sulfide have been shown to alleviate anxiety through distinct molecular mechanisms. Long-term administration of L-Cysteine has anxiolytic, antidepressant, and memory-improving effects. L-Cysteine depletion can lead to increased oxidative stress in the brain. This review delves into the potential mechanisms of L-Cysteine and its main products, glutathione (GSH) and hydrogen sulfide (H2S) in the management of anxiety and related diseases.

Antidepressive synergism between crocin and D-AP5 in acute restraint-stressed mice

Emerging evidence suggests that crocin rescues stress-induced depressive symptoms in mice via stimulation of hippocampal neurogenesis. Glutamate modulators mainly involving N-methyl- d -aspartate (NMDA) receptors (NMDARs) have highlighted a role in neural development, synaptic plasticity, and depression. The research presented here was designed to appraise the interaction between NMDAR agents and crocin on depressive-related behaviors in the NMRI male mice exposed to acute restraint stress (ARS) for a period of 4 h. The mice were submitted to the splash test, forced swimming test, and tail suspension test to evaluate depressive-like behavior. The ARS decreased the grooming duration in the splash test and increased immobility time in the forced swimming test and tail suspension test, suggesting a depressive-like phenotype. NMDA (0.25 and 0.5 μg/mouse, intracerebroventricular) did not alter depression-related profiles in both non-acute restraint stress (NARS) and ARS mice, while the same doses of NMDAR antagonist D-AP5 potentiated the antidepressive-like activities in the ARS mice compared with the NARS mice. Moreover, a low dose of NMDA did not change depression-related parameters in the crocin-treated NARS or ARS mice, while D-AP5 enhanced the crocin response in the NARS and ARS mice. Isobologram analysis noted a synergism between crocin and D-AP5 on antidepressive-like behavior in the NARS and ARS mice. Collectively, the combination of crocin and D-AP5 was shown to mitigate depression symptoms and can be potentially used for the treatment of depression disorders.

Deciphering the role of siRNA in anxiety and depression

Anxiety and depression are central nervous system illnesses that are among the most prevalent medical concerns of the twenty-first century. Patients with this condition and their families bear psychological, financial, and societal hardship. There are currently restrictions when utilizing the conventional course of treatment. RNA interference is expected to become an essential approach in anxiety and depression due to its potent and targeted gene silencing. Silencing of genes by post-transcriptional modification is the mechanism of action of small interfering RNA (siRNA). The suppression of genes linked to disease is typically accomplished by siRNA molecules in an efficient and targeted manner. Unfavourable immune responses, off-target effects, naked siRNA instability, nuclease vulnerability, and the requirement to create an appropriate delivery method are some of the challenges facing the clinical application of siRNA. This review focuses on the use of siRNA in the treatment of anxiety and depression.

Neuroprotective Effects of Cannabispirenone A against NMDA-Induced Excitotoxicity in Differentiated N2a Cells

The endocannabinoid system is found throughout the central nervous system, and its cannabinoids receptor 1 is critical in preventing neurotoxicity caused by N-methyl-D-aspartate receptor activation (NMDARs). The activity of NMDARs places demands on endogenous cannabinoids to regulate their calcium currents. Endocannabinoids keep NMDAR activity within safe limits, protecting neural cells from excitotoxicity. Cannabinoids are remembered to deliver this outcome by repressing presynaptic glutamate discharge or obstructing postsynaptic NMDAR-managed flagging pathways. The endocannabinoid system must exert a negative influence proportional to the strength of NMDAR signaling for such control to be effective. The goal of this paper is to draw the attention towards the neuroprotective mechanism of constituents of Cannabis sativa against NMDA-induced excitotoxic result. Phytochemical investigation of the cannabis flowers led to the isolation of nine secondary metabolites. A spiro-compound, Cannabispirenone A, which on treatment of the cells prior to NMDA exposure significantly increases cell survival while decreasing ROS production, lipid peroxidation, and intracellular calcium. Our findings showed that this compound showed neuroprotection against NMDA-induced excitotoxic insult, has antioxidative properties, and increased cannabinoid receptor 1 expression, which may be involved in the signaling pathway for this neuroprotection.

Neurobehavioral protective effects of Japanese sake yeast supplement against chronic stress-induced anxiety and depression-like symptoms in mice: Possible role of central adenosine receptors

RATIONALE

Using routine synthetic drugs in the treatment of psychiatric disorders may have some restrictions due to serious side effects and pharmacoresistance. Some natural agents may be promising alternatives in this case. The neuroprotective activity of the neuromodulator adenosine and its receptor, A1 receptor (A1R) in the central nervous system has been mentioned in different studies.

OBJECTIVE

We aimed to determine the anxiolytic, antidepressant and sedative effects of Japanese sake yeast as the first report.

METHOD

Mice were subjected to a one-week stress protocol and concomitantly treated orally with sake yeast at the dose levels of 100, 200 and 300 mg kg-1 once daily for a week. The anxiolytic, antidepressant, and sedative actions of sake yeast were evaluated with the related tests.

RESULTS

In all dose regiments, sake yeast significantly improved functions in the EPM and FST. 200 and 300 mg/kg of sake yeast significantly increased sleep duration and reduced sleep latency. Anxiolytic and antidepressant-like activities of sake yeast were maintained by the injection of ZM241385 (15 mg kg-1), a selective adenosine A2AR antagonist but completely counteracted by the injection of 8-cyclopentyltheophylline (10 mg kg-1), a selective adenosine A1R antagonist. 300 mg/kg of the yeast significantly increased the BDNF levels. Amygdala corticosterone levels did not show any significant changes at any dosage. Amygdala TNF-α, IL-6 and IL-1β levels also decreased significantly with all the sake regiments compared to the control group.

CONCLUSIONS

We conclude that oral sake yeast supplement exerts a neurobehavioral protective effect predominantly by activating central A1Rs.

PI3K-AKT/mTOR Signaling in Psychiatric Disorders: A Valuable Target to Stimulate or Suppress?

Economic development and increased stress have considerably increased the prevalence of psychiatric disorders in recent years, which rank as some of the most prevalent diseases globally. Several factors, including chronic social stress, genetic inheritance, and autogenous diseases, lead to the development and progression of psychiatric disorders. Clinical treatments for psychiatric disorders include psychotherapy, chemotherapy, and electric shock therapy. Although various achievements have been made researching psychiatric disorders, the pathogenesis of these diseases has not been fully understood yet, and serious adverse effects and resistance to antipsychotics are major obstacles to treating patients with psychiatric disorders. Recent studies have shown that the mammalian target of rapamycin (mTOR) is a central signaling hub that functions in nerve growth, synapse formation, and plasticity. The PI3K-AKT/mTOR pathway is a critical target for mediating the rapid antidepressant effects of these pharmacological agents in clinical and preclinical research. Abnormal PI3K-AKT/mTOR signaling is closely associated with the pathogenesis of several neurodevelopmental disorders. In this review, we focused on the role of mTOR signaling and the related aberrant neurogenesis in psychiatric disorders. Elucidating the neurobiology of the PI3K-AKT/mTOR signaling pathway in psychiatric disorders and its actions in response to antidepressants will help us better understand brain development and quickly identify new therapeutic targets for the treatment of these mental illnesses.

Ketamine - A New Antidepressant Drug with Anti-Inflammatory Properties

Ketamine is a new, potent and rapid-acting antidepressant approved for therapy of treatment-resistant depression, which has a different mechanism of action than currently-available antidepressant therapies. It owes its uniquely potent antidepressant properties to a complex mechanism of action, which currently remains unclear. However, it is thought that it acts by modulating the functioning of the glutamatergic system, which plays an important role in the process of neuroplasticity associated with depression. However, preclinical and clinical studies have also found ketamine to reduce inflammation, either directly or indirectly (by activating neuroprotective branches of the kynurenine pathway), among patients exhibiting higher levels of inflammation. Inflammation and immune system activation are believed to play key roles in the development and course of depression. Therefore, the present work examines the role of the antidepressant effect of ketamine and its anti-inflammatory properties in the treatment of depression. SIGNIFICANCE STATEMENT: The present work examines the relationship between the antidepressant effect of ketamine and its anti-inflammatory properties, and the resulting benefits in treatment-resistant depression (TRD). The antidepressant mechanism of ketamine remains unclear, and there is an urgent need to develop new therapeutic strategies for treatment of depression, particularly TRD.

Boltzmann's Theorem Revisited: Inaccurate Time-to-Action Clocks in Affective Disorders

Timely goal-oriented behavior is essential for survival and is shaped by experience. In this paper, a multileveled approach was employed, ranging from the polymorphic level through thermodynamic molecular, cellular, intracellular, extracellular, non-neuronal organelles and electrophysiological waves, attesting for signal variability. By adopting Boltzmann's theorem as a thermodynamic conceptualization of brain work, we found deviations from excitation-inhibition balance and wave decoupling, leading to wider signal variability in affective disorders compared to healthy individuals. Recent evidence shows that the overriding on-off design of clock genes paces the accuracy of the multilevel parallel sequencing clocks and that the accuracy of the time-to-action is more crucial for healthy behavioral reactions than their rapidity or delays. In affective disorders, the multilevel clocks run free and lack accuracy of responsivity to environmentally triggered time-to-action as the clock genes are not able to rescue mitochondria organelles from oxidative stress to produce environmentally-triggered energy that is required for the accurate time-to-action and maintenance of the thermodynamic equilibrium. This maintenance, in turn, is dependent on clock gene transcription of electron transporters, leading to higher signal variability and less signal accuracy in affective disorders. From a Boltzmannian thermodynamic and energy-production perspective, the option of reversibility to a healthier time-toaction, reducing entropy is implied. We employed logic gates to show deviations from healthy levelwise communication and the reversed conditions through compensations implying the role of nonneural cells and the extracellular matrix in return to excitation-inhibition balance and accuracy in the time-to-action signaling.

[Targeting NMDAR/AMPAR: a promising pharmacotherapeutic approach for depressive disorders]

Depression is a leading cause of disability and reduced work capacity worldwide. The monoamine theory of the pathogenesis of depression has remained dominant for many decades, however, drugs developed on its basis have limited efficacy. Exploring alternative mechanisms underlying this pathology could illuminate new avenues for pharmacological intervention. Targeting glutamatergic pathways in the CNS, particularly through modulation of NMDA and AMPA receptors, demonstrates promising results. This review presents some existing drugs with glutamatergic activity and novel developments based on it to enhance the efficacy of pharmacotherapy for depressive disorders.

Role of Imaging Modalities and N-Acetylcysteine Treatment in Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy is a severe systemic infection complication. Although early stages involve pathophysiological changes, detection using conventional imaging is challenging. Glutamate chemical exchange saturation transfer and diffusion kurtosis imaging can noninvasively investigate cellular and molecular events in early disease stages using magnetic resonance imaging (MRI). N-Acetylcysteine, an antioxidant and precursor of glutathione, regulates neurotransmitter glutamate metabolism and participates in neuroinflammation. We investigated the protective role of n-acetylcysteine in sepsis-associated encephalopathy using a rat model and monitored changes in brain using magnetic resonance (MR) molecular imaging. Bacterial lipopolysaccharide was injected intraperitoneally to induce a sepsis-associated encephalopathy model. Behavioral performance was assessed using the open-field test. Tumor necrosis factor α and glutathione levels were detected biochemically. Imaging was performed using a 7.0-T MRI scanner. Protein expression, cellular damage, and changes in blood-brain barrier permeability were assessed using western blotting, pathological staining, and Evans blue staining, respectively. Lipopolysaccharide-induced rats showed reduced anxiety and depression after treatment with n-acetylcysteine. MR molecular imaging can identify pathological processes at different disease stages. Furthermore, rats treated with n-acetylcysteine showed increased glutathione levels and decreased tumor necrosis factor α, suggesting enhanced antioxidant capacity and inhibition of inflammatory processes, respectively. Western blot analysis showed reduced expression of nuclear factor kappa B (p50) protein after treatment, suggesting that n-acetylcysteine inhibits inflammation via this signaling pathway. Finally, n-acetylcysteine-treated rats showed reduced cellular damage by pathology and reduced extravasation of their blood-brain barrier by Evans Blue staining. Thus, n-acetylcysteine might be a therapeutic option for sepsis-associated encephalopathy and other neuroinflammatory diseases. Furthermore, noninvasive "dynamic visual monitoring" of physiological and pathological changes related to sepsis-associated encephalopathy was achieved using MR molecular imaging for the first time, providing a more sensitive imaging basis for early diagnosis, identification, and prognosis.

Correlations between GRIN2B and GRIN3A gene polymorphisms and postpartum depressive symptoms in Chinese parturients undergoing cesarean section: A prospective cohort study

OBJECTIVE

To investigate the association of postpartum depressive symptoms (PDS) and self-harm ideation with n-methyl-d-aspartate (NMDA) receptor GRIN2B and GRIN3A gene polymorphisms and other risk factors in women undergoing cesarean section.

METHODS

A total of 362 parturients undergoing cesarean section under lumbar anesthesia were selected and their postpartum depression level was assessed by the Edinburgh Postpartum Depression Scale (EPDS) at 42 days postpartum, with an EPDS score of 9/10 as the cut-off value. Three GRIN2B SNP loci (rs1805476, rs3026174, rs4522263) and five GRIN3A SNP loci (rs1983812, rs2050639, rs2050641, rs3739722, rs10989563) were selected for genotype detection. The role of each SNP, linkage disequilibrium and haplotypes in the development of postpartum depression was analyzed. Logistic regression analysis was performed for related risk factors.

RESULTS

PDS incidence was 16.85%, and self-harm ideation incidence was 13.54%. Univariate analysis showed that GRIN2B rs1805476, rs3026174 and rs4522263 gene polymorphisms were associated with PDS (p < 0.05), with GRIN2B rs4522263 gene also associated with maternal self-harm ideation. GRIN3A rs1983812, rs2050639, rest rs2050641, rs3739722 and rs10989563 alleles were not associated with PDS. Logistic regression analysis indicated that high pregnancy stress, as well as rs1805476 and rs4522263 alleles were PDS risk factors following cesarean delivery. GRIN2B (TTG p = 0.002) and GRIN3A (TGTTC p = 0.002) haplotypes were associated with the lower PDS incidence and higher PDS incidence respectively.

CONCLUSION

GRIN2B rs1805476 GG genotype, rs4522263 CC genotype and high stress during pregnancy were risk factors for PDS, whilst a significantly higher incidence of self-harm ideation was evident in parturients carrying GRIN2B rs4522263 CC genotype.

Efficacy and tolerability of Lavandula angustifolia in treating patients with the diagnosis of depression: a systematic review of randomized controlled trials

Pharmacotherapy is the conventional treatment for depression, with only half of the patients responding to the first trial of monotherapy with first-line medicines. One way to overcome this resistance is to use complementary and alternative medicine. The antidepressant effects of Lavandula angustifolia, which is commonly called lavender, have been investigated in previous studies. This study aims to provide the first systematic review of lavender in treating patients with depression diagnosis. ISI Web of Science, Scopus, PubMed, Embase, PsycINFO, Google Scholar, and three trial registries were searched until May 2020 to find randomized controlled trials on lavender for depressed patients. The primary outcome was difference between the intervention and control groups in changing depression scores from baseline to endpoint. The included studies were assessed for effect size and methodological quality. Seven clinical trials were identified, in which 852 patients were studied. In six trials, the effectiveness of lavender in treating depression was reported, as being more pronounced adjunct to a typical antidepressant in one study. Significant reported side effects include headaches and eructation. Lavender is beneficial, tolerable, and safe in treating depression. Despite obtaining promising results, they are not enough to recommend prescribing lavender to depressed patients. Further high-quality, large-scale studies for rectifying the shortcomings of existing studies are recommended.

Glutamatergic neurotransmission: A potential pharmacotherapeutic target for the treatment of cognitive disorders

In the mammalian brain, glutamate is regarded to be the primary excitatory neurotransmitter due to its widespread distribution and wide range of metabolic functions. Glutamate plays key roles in regulating neurogenesis, synaptogenesis, neurite outgrowth, and neuron survival in the brain. Ionotropic and metabotropic glutamate receptors, neurotransmitters, neurotensin, neurosteroids, and others co-ordinately formulate a complex glutamatergic network in the brain that maintains optimal excitatory neurotransmission. Cognitive activities are potentially synchronized by the glutamatergic activities in the brain via restoring synaptic plasticity. Dysfunctional glutamate receptors and other glutamatergic components are responsible for the aberrant glutamatergic activity in the brain that cause cognitive impairments, loss of synaptic plasticity, and neuronal damage. Thus, controlling the brain's glutamatergic transmission and modifying glutamate receptor function could be a potential therapeutic strategy for cognitive disorders. Certain drugs that regulate glutamate receptor activities have shown therapeutic promise in improving cognitive functions in preclinical and clinical studies. However, several issues regarding precise functional information of glutamatergic activity are yet to be comprehensively understood. The present article discusses the scope of developing glutamatergic systems as prospective pharmacotherapeutic targets to treat cognitive disorders. Special attention has been given to recent developments, challenges, and future prospects.

Determination of D-serine and D-alanine Tissue Levels in the Prefrontal Cortex and Hippocampus of Rats After a Single Dose of Sodium Benzoate, a D-Amino Acid Oxidase Inhibitor, with Potential Antipsychotic and Antidepressant Properties

The effects of the N-methyl-D-aspartate receptor activators D-serine, D-alanine, and sarcosine against schizophrenia and depression are promising. Nevertheless, high doses of D-serine and sarcosine are associated with undesirable nephrotoxicity or worsened prostatic cancer. Thus, alternatives are needed. DAAO inhibition can increase D-serine as well as D-alanine and protect against D-serine-induced nephrotoxicity. Although several DAAO inhibitors improve the symptoms of schizophrenia and depression, they can increase the plasma levels but not brain levels of D-serine. The mechanism of action of DAAO inhibitors remains unclear. We investigated the effects of the DAAO inhibitor sodium benzoate on the prefrontal cortex and hippocampal level of D-alanine as known another substrate with antipsychotic and antidepressant properties and other NMDAR-related amino acids, such as, L-alanine, D-serine, L-serine, D-glutamate, L-glutamate, and glycine levels. Our results indicate that sodium benzoate exerts antipsychotic and antidepressant-like effects without changing the D-serine levels in the brain prefrontal cortex (PFC) and hippocampus. Moreover, D-alanine levels in the PFC and hippocampus did not change. Despite these negative findings regarding the effects of D-amino acids in the PFC and hippocampus, sodium benzoate exhibited antipsychotic and antidepressant-like effects. Thus, the therapeutic effects of sodium benzoate are independent of D-serine or D-alanine levels. In conclusion, sodium benzoate may be effective among patients with schizophrenia or depression; however, the mechanisms of actions remain to be elucidated.

Neural Correlates of the DEEPP (Anti-suicidal Response to Ketamine in Treatment-Resistant Bipolar Depression) Study: Protocol for a Pilot, Open-Label Clinical Trial

BACKGROUND

Suicide is among the top 10 leading causes of death worldwide. Of people who died by suicide, the majority are diagnosed with depression. It is estimated that 25%-60% of people with bipolar depression (BD) will attempt suicide at least once, and 10%-15% will die by suicide. Several treatments, such as lithium, clozapine, electroconvulsive therapy, and cognitive behavioral therapy, have been shown to be effective in treating suicidality. However, these treatments can be difficult to tolerate or may take months to take effect. Ketamine, a glutamate N-methyl-D-aspartate antagonist, has been shown to have rapid antisuicidal effect and antidepressant qualities, and is thus a promising intervention to target acute suicidality in patients with BD. However, the biological mechanism underlying its therapeutic action remains poorly understood. Enhancing our understanding of underlying mechanisms of action for ketamine's effectiveness in reducing suicidality is critical to establishing biological markers of treatment response and developing tailored, personalized interventions for patients with BD.

OBJECTIVE

This is an open-label clinical trial to test the safety and feasibility of repeated ketamine infusions to treat acute suicidality. The primary objective is to test the safety and feasibility of ketamine intervention. The secondary objective is to examine ketamine's potential neurophysiological mechanisms of action by assessing cortical excitation and inhibition to determine potential biomarkers of clinical response. Other objectives are to evaluate the effect of ketamine on acute suicidality and other clinical outcomes, such as depressive symptoms and quality of life, to inform a future larger trial.

METHODS

This open-label clinical trial aims to test the safety and feasibility of repeated ketamine infusions in patients with BD for suicidality and to assess ketamine's neurophysiological effects. A sterile form of racemic ketamine hydrochloride will be administered over a 40-minute intravenous infusion 2 times per week on nonconsecutive days for 4 weeks (8 sessions). We will recruit 30 adults (24-65 year olds) over 2 years from an academic psychiatric hospital in Toronto, Canada.

RESULTS

This study is currently ongoing and actively recruiting participants. So far, 5 participants have completed the trial, 1 is currently in active treatment, and 8 participants are on the waitlist to be screened. We anticipate initial results being available in the fall of 2023. This proposal was presented as a poster presentation at the Research to Reality Global Summit on Psychedelic-Assisted Therapies and Medicine, held in May 2022 in Toronto, Canada.

CONCLUSIONS

Developing effective interventions for acute suicidality in high-risk populations such as those with BD remains a major therapeutic challenge. Ketamine is a promising treatment due to its rapid antidepressant and antisuicidal effects, but its underlying neurophysiological mechanisms of action remain unknown.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05177146; https://clinicaltrials.gov/ct2/show/NCT05177146.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/41013.

Role of imaging modalities and N-acetylcysteine treatment in sepsis-associated encephalopathy.. [DOI: 10.21203/rs.3.rs-2459747/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background Sepsis-associated encephalopathy is a severe complication due to systemic infection. Although early stages involve pathophysiological changes, detection using conventional imaging is challenging. Glutamate chemical exchange saturation transfer and diffusion kurtosis imaging can noninvasively investigate cellular and molecular events in the early stage of the disease by MRI. N-acetylcysteine, an antioxidant and precursor of glutathione, regulates the metabolism of the neurotransmitter glutamate and participates in neuroinflammation. We aimed to investigate the protective role of n-acetylcysteine in sepsis-associated encephalopathy using a rat model and monitor changes in the brain using magnetic resonance molecular imaging. Methods Bacterial lipopolysaccharide was injected intraperitoneally into the rats to induce a sepsis-associated encephalopathy model. The behavioural performance was assessed using the open field test. Tumour necrosis factor alpha and glutathione levels were detected biochemically. Imaging was performed using a 7.0-T MRI scanner. Protein expressions and cellular damage were assessed by western blotting and pathological staining, respectively. We also evaluated changes in the blood-brain barrier permeability by the Evans blue staining. Results The lipopolysaccharide-induced rats showed reduced anxiety and depression after treatment with n-acetylcysteine. Magnetic resonance molecular imaging can identify pathological processes at different stages of the disease. Furthermore, rats treated with n-acetylcysteine showed increased glutathione levels and decreased tumour necrosis factor alpha, suggesting enhanced antioxidant capacity and inhibition of inflammatory processes, respectively. Western blot analysis showed a reduced expression of nuclear factor kappa B (p50) protein after treatment, suggesting that n-acetylcysteine inhibits inflammation via this signalling pathway. Finally, n-acetylcysteine treated rats also showed reduced cellular damage by pathology and reduced extravasation of their blood-brain barrier by Evan Blue staining. Conclusion This study showed that n-acetylcysteine might be a therapeutic option for sepsis-associated encephalopathy and other neuroinflammatory diseases. Furthermore, non-invasive ‘dynamic visual monitoring’ of the physiological and pathological changes related to sepsis-associated encephalopathy was achieved for the first time using magnetic resonance molecular imaging, which provides a more sensitive imaging basis for early clinical diagnosis, identification, and prognosis.

Prophylactic Efficacy of Riluzole against Anxiety- and Depressive-Like Behaviors in Two Rodent Stress Models

Introduction

Chronic stress-related illnesses such as major depressive disorder and post-traumatic stress disorder share symptomatology, including anxiety, anhedonia, and helplessness. Across disorders, neurotoxic dysregulated glutamate (Glu) signaling may underlie symptom emergence. Current first-line antidepressant drugs, which do not directly target Glu signaling, fail to provide adequate benefit for many patients and are associated with high relapse rates. Riluzole modulates glutamatergic neurotransmission by increasing metabolic cycling and modulating signal transduction. Clinical studies exploring riluzole's efficacy in stress-related disorders have provided varied results. However, the utility of riluzole for treating specific symptom dimensions or as a prophylactic treatment has not been comprehensively assessed.

Methods

We investigated whether chronic prophylactic riluzole (∼12-15 mg/kg/day p.o.) could prevent the emergence of behavioral deficits induced by unpredictable chronic mild stress (UCMS) in mice. We assessed (i) anxiety-like behavior using the elevated-plus maze, open-field test, and novelty-suppressed feeding, (ii) mixed anxiety/anhedonia-like behavior in the novelty-induced hypophagia test, and (iii) anhedonia-like behavior using the sucrose consumption test. Z-scoring summarized changes across tests measuring similar dimensions. In a separate learned helplessness (LH) cohort, we investigated whether chronic prophylactic riluzole treatment could block the development of helplessness-like behavior.

Results

UCMS induced an elevation in anhedonia-like behavior and overall behavioral emotionality that was blocked by prophylactic riluzole. In the LH cohort, prophylactic riluzole blocked the development of helplessness-like behavior.

Discussion/Conclusion

This study supports the utility of riluzole as a prophylactic medication for preventing anhedonia and helplessness symptoms associated with stress-related disorders.

Central Stimulatory Effect of Kynurenic Acid on BDNF-TrkB Signaling and BER Enzymatic Activity in the Hippocampal CA1 Field in Sheep

Deficiency of neurotrophic factors and oxidative DNA damage are common causes of many neurodegenerative diseases. Recently, the importance of kynurenic acid (KYNA), an active metabolite of tryptophan, has increased as a neuroprotective molecule in the brain. Therefore, the present study tested the hypothesis that centrally acting KYNA would positively affect: (1) brain-derived neurotrophic factor (BDNF)-tyrosine receptor kinase B (TrkB) signaling and (2) selected base excision repair (BER) pathway enzymes activities in the hippocampal CA1 field in sheep. Both lower (20 μg in total) and higher (100 μg in total) doses of KYNA infused into the third brain ventricle differentially increased the abundance of BDNF and TrkB mRNA in the CA1 field; additionally, the higher dose increased BDNF tissue concentration. The lower dose of KYNA increased mRNA expression for 8-oxoguanine glycosylase (OGG1), N-methylpurine DNA glycosylase (MPG), and thymine DNA glycosylase and stimulated the repair of 1,N6-ethenodeoxyadenosine and 3,N4-ethenodeoxy-cytosine as determined by the excision efficiency of lesioned nucleobases. The higher dose increased the abundance of OGG1 and MPG transcripts, however, its stimulatory effect on repair activity was less pronounced in all cases compared to the lower dose. The increased level of AP-endonuclease mRNA expression was dose-dependent. In conclusion, the potential neurotrophic and neuroprotective effects of KYNA in brain cells may involve stimulation of the BDNF-TrkB and BER pathways.

Ginsenoside-Rg1 mitigates cardiac arrest-induced cognitive damage by modulating neuroinflammation and hippocampal plasticity

Ginsenoside-Rg1 can effectively ameliorate mental disorders, but whether ginsenoside-Rg1 plays a neuroprotective role in cardiac arrest and cardiopulmonary resuscitation (CA/CPR)-induced cognitive impairment remains unclear. In this study, a 5-min asphyxia-based CA/CPR rat model was established to explore the mechanisms underlying the effects of ginsenoside-Rg1 (40 mg·kg-1·d-1, ip, 14 days) on its cognitive alterations. These CA/CPR rats displayed spatial learning and memory impairment in the Morris water maze, as reflected in the compromised basal synaptic transmission and long-term potentiation (LTP) at the Schaffer collateral of hippocampal CA1 area in vivo electrophysiology, whereas the ginsenoside-Rg1 remarkably mitigated these alterations. Next, we found that ginsenoside-Rg1 inhibited hippocampal neuroinflammation by alleviating the CA/CPR-induced hippocampal activation of microglia and astrocytes and the overexpression of related proinflammatory cytokines interleukin-1β (IL-1β) and tumour necrosis factor-α (TNF-α). In addition, ginsenoside-Rg1 improved CA/CPR-induced hippocampal neuronal apoptosis, dendritic spines and synaptic ultrastructure defects as associated with the upregulation of the key synaptic regulatory proteins. Furthermore, ginsenoside-Rg1 could ameliorate CA/CPR-induced aberrant expression of the key regulators of hippocampal glutamate signaling pathways, excitatory amino acid transporter 2 (EAAT2), excitatory amino acid transporter 1 (EAAT1), Glutamine Synthetase (GS), GluN2B, and glutamate. In conclusion, ginsenoside-Rg1 exerts its neuroprotective effects by ameliorating hippocampus-dependent neuroglia activation-mediated neuroinflammation and neuroplasticity deficits, shedding new light on the therapeutic intervention of CA/CPR-related cognitive disorders.

Gut microbiota-mediated metabolic restructuring aggravates emotional deficits after anesthesia/surgery in rats with preoperative stress

Patients with preoperative stress are prone to postoperative emotional deficits. However, the underlying mechanisms are largely unknown. Here, we characterize the changes of microbial composition and specific metabolites after anesthesia/surgery in rats with preoperative stress based on 16S rRNA gene sequencing and non-targeted metabolomics technique. Consequently, we found that anesthesia/surgery aggravated anxiety-like and depression-like behaviors in rats under preoperative stress. Microglia were activated and pro-inflammatory cytokines, including interleukin 6 (IL-6) and tumor necrosis factor ɑ (TNF-α) were upregulated after anesthesia/surgery. The postoperative gut microbiota and metabolite composition of rats exposed to preoperative stress differed from those of control rats. Lastly, emotional impairments, metabolic alterations, and neuroinflammation returned normal in antibiotics-treated rats. Our findings provide further evidence that abnormalities in the gut microbiota contribute to postoperative metabolic restructuring, neuroinflammation, and psychiatric deficits in rats under preoperative stress.

Depression in Parkinson's Disease: A Narrative Review

Parkinson's disease (PD) is a progressive neurodegenerative age-related disorder that affects the central nervous system (CNS) and is characterized by uncontrollable movements such as shaking, stiffness, and loss of balance and coordination. Depression is a common non-motor manifestation of PD, but unfortunately, depression remains unrecognized and often undertreated. The underlying pathophysiology of depression in PD is complicated, and many studies have been conducted to know the exact cause, but the question remains unanswered.

In this article, we discuss various pathophysiologies by which depression occurs in PD. The most widely accepted theories are neuroinflammation and monoamine oxidase theory. This article also explored the pharmacological treatment of depression in PD; this involves standard antidepressant therapy such as tricyclic antidepressants (TCA), serotonin-norepinephrine reuptake inhibitors (SNRI), selective serotonin reuptake inhibitors (SSRI), and monoamine oxidase inhibitors (MAO); non-pharmacological treatments such as electroconvulsive therapy (ECT), cognitive-behavioral therapy (CBT) have also been discussed. However, physicians hesitate to prescribe antidepressants to patients with PD due to concerns about harmful drug-drug interactions between antidepressants and antiparkinsonian drugs. Despite the complicated link between PD and depression, the co-administration of antidepressants and antiparkinsonian drugs is safe and beneficial when appropriately managed. However, early recognition and initiation of treatment of depression in PD reduces the longitudinal course and improves the cross-sectional picture. This review article also explored the clinical and diagnostic findings and impact on the quality of life of depression in PD.

The Application of the Neuroprotective and Potential Antioxidant Effect of Ergotamine Mediated by Targeting N-Methyl-D-Aspartate Receptors

(1) Background: The N-methyl-D-aspartate receptors (NMDARs) mediate fast excitatory currents leading to depolarization. Postsynaptic NMDARs are ionotropic glutamate receptors that mediate excitatory glutamate or glycine signaling in the CNS and play a primary role in long-term potentiation, which is a major form of use-dependent synaptic plasticity. The overstimulation of NMDARs mediates excessive Ca²⁺ influx to postsynaptic neurons and facilitates more production of ROS, which induces neuronal apoptosis. (2) Methods: To confirm the induced inward currents by the coapplication of glutamate and ergotamine on NMDARs, a two-electrode voltage clamp (TEVC) was conducted. The ergotamine-mediated inhibitory effects of NR1a/NR2A subunits were explored among four different kinds of recombinant NMDA subunits. In silico docking modeling was performed to confirm the main binding site of ergotamine. (3) Results: The ergotamine-mediated inhibitory effect on the NR1a/NR2A subunits has concentration-dependent, reversible, and voltage-independent properties. The major binding sites were V169 of the NR1a subunit and N466 of the NR2A subunit. (4) Conclusion: Ergotamine effectively inhibited NR1a/NR2A subunit among the subtypes of NMDAR. This inhibition effect can prevent excessive Ca²⁺ influx, which prevents neuronal death.

Baihe Dihuang (Lilium Henryi Baker and Rehmannia Glutinosa) decoction attenuates somatostatin interneurons deficits in prefrontal cortex of depression via miRNA-144-3p mediated GABA synthesis and release

ETHNOPHARMACOLOGICAL RELEVANCE

Baihe Dihuang Decoction is a well-known traditional Chinese medicine prescription (Also known as Lilium Henryi Baker and Rehmannia Glutinosa Decoction, LBRD) composed of Lilium Henryi Baker bulb and raw juice from Rehmannia Glutinosa (Gaertn) DC with the curative efficacy of nourishing yin and clearing heat based on the Chinese herbal medicine theory. It has been used as routine medication in treating depression combined with conventional western medicine in China for years.

AIM OF THE STUDY

LBRD can attenuates GABAergic deficits in the medial prefrontal cortex (mPFC) of depression. This study aimed to investigate the mechanism of antidepressive properties of LBRD in the prefrontal GABAergic interneuron subtypes, including parvalbumin (PV), somatostatin (SST), vasoactive intestinal peptide (VIP)-positive neuron.

MATERIALS AND METHODS

In this project, chronic unpredicted mild stress paradigm was adopted to construct depression model. After treated with LBRD standard decoction and behaviors test, the level of GABA associated miRNA/mRNA and GABAergic subtype-specific markers were detected by qRT-PCR and Western blot. The lncRNAs/miRNAs/GABA regulatory axis was verified by luciferase reporter assay, RNA immunoprecipitation, RNA pull-down assay, and theses changes were measured in LBRD administration with the use of immunofluorescence staining and RNA-fluorescence in situ hybridization.

RESULTS

In the current study, we found that LBRD exhibited high efficacy based on the results of behavioral tests. Meanwhile, LBRD also improved the reduced GABA levels in depression by increasing the expression of lncRNA Neat1 and Malat1, as well as decreasing miRNA-144-3p and miRNA-15b-5p. Moreover, the level of Sst mRNA and protein that were harvested from the mPFC tissues of depression group was significantly lower than those in the control mice. While, these changes can be reverted by LBRD standard decoction administration. Whereas, neither chronic stress nor treatment can change the level of PV and VIP mRNAs and protein expression. In the SST-positive neuron of mPFC tissues, treatment with LBRD standard decoction resulted in the elevation of Gad-67, VGAT, GAT-3 and a reduction of miRNA-144-3p expression.

CONCLUSIONS

These findings suggested that LBRD antidepressant activities may be related to ameliorating the SST-positive neuron deficits via regulating the miRNA-144-3p mediated GABA synthesis and release.

Sigma-1 Receptors in Depression: Mechanism and Therapeutic Development

Depression is the most common type of neuropsychiatric illness and has increasingly become a major cause of disability. Unfortunately, the recent global pandemic of COVID-19 has dramatically increased the incidence of depression and has significantly increased the burden of mental health care worldwide. Since full remission of the clinical symptoms of depression has not been achieved with current treatments, there is a constant need to discover new compounds that meet the major clinical needs. Recently, the roles of sigma receptors, especially the sigma-1 receptor subtype, have attracted increasing attention as potential new targets and target-specific drugs due to their translocation property that produces a broad spectrum of biological functions. Even clinical first-line antidepressants with or without affinity for sigma-1 receptors have different pharmacological profiles. Thus, the regulatory role of sigma-1 receptors might be useful in treating these central nervous system (CNS) diseases. In addition, long-term mental stress disrupts the homeostasis in the CNS. In this review, we discuss the topical literature concerning sigma-1 receptor antidepressant mechanism of action in the regulation of intracellular proteostasis, calcium homeostasis and especially the dynamic Excitatory/Inhibitory (E/I) balance in the brain. Furthermore, based on these discoveries, we discuss sigma-1 receptor ligands with respect to their promise as targets for fast-onset action drugs in treating depression.

Integrating Metabolomics and Network Analysis for Exploring the Mechanism Underlying the Antidepressant Activity of Paeoniflorin in Rats With CUMS-Induced Depression

Background: Paeoniflorin (PF) represents the major bioactive constituent of the traditional Chinese medicine plant Paeonia suffruticosa (Ranunculaceae), which has a long history as a folk medicine in Asian. Paeoniflorin, a bitter pinene monoterpene glycoside, has antidepressant effects, but its potential therapeutic mechanism has not been thoroughly explored.

Methods: Experimental depression in rats was established by the chronic unpredictable mild stress (CUMS) combined with orphan method, and the efficacy of paeoniflorin on depression was evaluated by the sucrose preference test and open field test. The antidepressant mechanism of paeoniflorin was investigated by metabolomic and network pharmacology. The relevant pathways of biomarkers highlighted in metabolomics were explored, and the possible targets of paeoniflorin in the treatment of depression were further revealed through network analysis. The binding activity of paeoniflorin to key targets was verified by molecular docking.

Results: Metabolomics showed that rats with CUMS-induced depression had urine metabolic disorders, which were reversed by paeoniflorin through the regulation of metabolic pathways. Metabolites that play a key role in the function of paeoniflorin include citric acid, thiamine monophosphate, gluconolactone, 5-hydroxyindoleacetic acid and stachyose. Key predicted targets are SLC6A4, TNF, IL6 and SLC6A3. An important metabolic pathway is the Citrate cycle (TCA cycle).

Conclusion: Network integrative analysis in this study showed that paeoniflorin could improve depressive-like symptoms in model rats with CUMS-induced depression and overall correct the disordered metabolic profile through multiple metabolic pathways.

Microbiome abnormalities as a possible link between diabetes mellitus and mood disorders: Pathophysiology and implications for treatment

Diabetes mellitus and mental health disorders create an immense burden on society worldwide. Knowledge of the cellular and biochemical connections linking these two pathologies has broadened and the mechanism for diet-induced shifts in the microbiota has become more refined. However, there remains limited understanding of the mechanism wherein changes in the microbiota affect the development and severity of these diseases and their interconnectedness. This review examines current literature to highlight a potential mechanism that links specific changes in the microbiome to mental health disorders and diabetes mellitus. Novel data indicate that alterations in the abundance and concentration of bacterium in the gut result in an elevated risk for developing mental and metabolic disorders. Through the mechanisms and downstream effects of short-chain fatty acids and the tryptophan metabolizing pathway, the onset of diabetes is shown to directly affect the development of mental health disorders. This paper provides a possible physiological mechanism connecting these two disorders, which could inform future research and policy decisions limiting the global impact of these diseases.

Sex differences in ketamine's therapeutic effects for mood disorders: A systematic review

Replicated clinical trials have demonstrated rapid and robust antidepressant effects with ketamine in treatment resistant mood disorders. Sex (biological) and gender differences in therapeutic effects for any new intervention is an important consideration, however, the differential efficacy, safety and tolerability of ketamine in males versus females remains underexplored. The objective of the present systematic review is to identify and qualitatively synthesize all published clinical studies relevant to the sex differential effects of ketamine for mood disorders. A systematic search of PubMed, Medline, and PsycInfo from inception until January 20, 2021, yielded 27 reports including 1715 patients (742 males and 973 females) that met inclusion criteria. Results from the vast majority of studies (88.8%) do not support significant sex differences in antidepressant response, tolerability or safety of ketamine. Nine (33.3%) of the reports included a bioanalytical component in the analysis and only one reported on sex differences. Evidence from the present review does not support clinically or statistically significant sex differences in therapeutic effects with ketamine. Nevertheless, future studies should continue to consider sex and biological sex differences in study design and data analytic plans.

Case Report: Developmental Delay and Acute Neuropsychiatric Episodes Associated With a de novo Mutation in the CAMK2B Gene (c.328G>A p.Glu110Lys)

Mutations in the genes encoding calcium/calmodulin dependent protein kinase II (CAMK2) isoforms cause a newly recognized neurodevelopmental disorder (ND), for which the full clinical spectrum has yet to be described. Here we report the detailed description of a child with a de novo gain of function (GoF) mutation in the gene Ca/Calmodulin dependent protein kinase 2 beta (CAMK2B c.328G > A p.Glu110Lys) who presents with developmental delay and periodic neuropsychiatric episodes. The episodes manifest as encephalopathy with behavioral changes, headache, loss of language and loss of complex motor coordination. Additionally, we provide an overview of the effect of different medications used to try to alleviate the symptoms. We show that medications effective for mitigating the child’s neuropsychiatric symptoms may have done so by decreasing CAMK2 activity and associated calcium signaling; whereas medications that appeared to worsen the symptoms may have done so by increasing CAMK2 activity and associated calcium signaling. We hypothesize that by classifying CAMK2 mutations as “gain of function” or “loss of function” based on CAMK2 catalytic activity, we may be able to guide personalized empiric treatment regimens tailored to specific CAMK2 mutations. In the absence of sufficient patients for traditional randomized controlled trials to establish therapeutic efficacy, this approach may provide a rational approach to empiric therapy for physicians treating patients with dysregulated CAMK2 and associated calcium signaling.

Inflammation and Nitro-oxidative Stress as Drivers of Endocannabinoid System Aberrations in Mood Disorders and Schizophrenia

The endocannabinoid system (ECS) is composed of the endocannabinoid ligands anandamide (AEA) and 2-arachidonoylgycerol (2-AG), their target cannabinoid receptors (CB₁ and CB₂) and the enzymes involved in their synthesis and metabolism (N-acyltransferase and fatty acid amide hydrolase (FAAH) in the case of AEA and diacylglycerol lipase (DAGL) and monoacylglycerol lipase (MAGL) in the case of 2-AG). The origins of ECS dysfunction in major neuropsychiatric disorders remain to be determined, and this paper explores the possibility that they may be associated with chronically increased nitro-oxidative stress and activated immune-inflammatory pathways, and it examines the mechanisms which might be involved. Inflammation and nitro-oxidative stress are associated with both increased CB₁ expression, via increased activity of the NADPH oxidases NOX4 and NOX1, and increased CNR1 expression and DNA methylation; and CB₂ upregulation via increased pro-inflammatory cytokine levels, binding of the transcription factor Nrf2 to an antioxidant response element in the CNR2 promoter region and the action of miR-139. CB₁ and CB₂ have antagonistic effects on redox signalling, which may result from a miRNA-enabled negative feedback loop. The effects of inflammation and oxidative stress are detailed in respect of AEA and 2-AG levels, via effects on calcium homeostasis and phospholipase A₂ activity; on FAAH activity, via nitrosylation/nitration of functional cysteine and/or tyrosine residues; and on 2-AG activity via effects on MGLL expression and MAGL. Finally, based on these detailed molecular neurobiological mechanisms, it is suggested that cannabidiol and dimethyl fumarate may have therapeutic potential for major depressive disorder, bipolar disorder and schizophrenia.

Repeated Yueju, But Not Fluoxetine, Induced Sustained Antidepressant Activity in a Mouse Model of Chronic Learned Helplessness: Involvement of CaMKII Signaling in the Hippocampus

OBJECTIVE

Depression is characterized with long disease length, whereas one major disadvantage of current mainstream treatment of depression is a high rate of relapse and recurrence. A sustained antidepressant activity is proposed to facilitate the prevention of relapse/recurrence. Here we compared the long-term antidepressant effect of Yueju, a traditional Chinese medicine formula, and a conventional antidepressant, fluoxetine, as well as revealing the underlying mechanism of long-term antidepressant effect of Yueju.

METHODS

Clinical long-term depression condition was modelled by using chronic learned helplessness (cLH) protocol in ICR strain mice. The short-term and long-term antidepressant effects of drugs were assessed with learned helplessness (LH), tail suspension test (TST), forced swim test (FST), and novelty-suppressed feeding (NSF) test. The expression of PKA, CaMKII signaling, and NR1, the NMDA receptor subunit, in hippocampus was determined. A CaMKII inhibitor (KN-62) was used to assess the role of CaMKII signaling in antidepressant effects of Yueju or fluoxetine.

RESULTS

In the mice exposed to chronic learned helplessness (cLH) procedure, administration of Yueju or fluoxetine for 3 weeks elicited comparable antidepressant effects, indicated by learned helplessness test, as well as TST and NSF. However, 5 days after termination of the 3-week-long drug administration, only mice previously treated with Yueju still showed the alleviation of depressive-like behaviors. At this time, the downregulation of PKA and p-CaMKII/CaMKII and upregulation of NMDA receptor subunit NR1 in the hippocampus were normalized in animals previously treated with Yueju. In contrast, none of the expressions of these proteins were changed in mice previously treated with fluoxetine. Interestingly, an administration of KN-62 blunted the antidepressant effect of Yueju.

CONCLUSION

These findings showed the sustained antidepressant efficacy of chronic treatment with routine dose of Yueju and the CaMKII signaling activation may play a critical role in the sustained antidepressant response.

Proteomics Study Reveals the Anti-Depressive Mechanisms and the Compatibility Advantage of Chaihu-Shugan-San in a Rat Model of Chronic Unpredictable Mild Stress

Background: Chaihu-Shugan-San is a classical prescription to treat depression. According to the traditional Chinese medicine (TCM) principle, the 2 decomposed recipes in Chaihu-Shugan-San exert synergistic effects, including Shu Gan (stagnated Gan-Qi dispersion) and Rou Gan (Gan nourishment to alleviate pain). However, the specific mechanism of Chaihu-Shugan-San on depression and its compatibility rule remain to be explored.

Objective: We aimed to explore the anti-depression mechanisms and analyze the advantage of TCM compatibility of Chaihu-Shugan-San.

Methods: The chronic unpredictable mild stress (CUMS) rat model was established. Antidepressant effects were evaluated by sucrose preference test (SPT), and forced swimming test (FST). Tandem Mass Tag (TMT)-based quantitative proteomics of the hippocampus was used to obtain differentially expressed proteins (DEPs). Bioinformatics analysis including Gene Ontology (GO), pathway enrichment, and protein-protein interaction (PPI) networks was utilized to study the DEPs connections. At last, the achieved key targets were verified by western blotting.

Results: Chaihu-Shugan-San increased weight gain and food intake, as well as exhibited better therapeutic effects including enhanced sucrose preference and extended immobility time when compared with its decomposed recipes. Proteomics showed Chaihu-Shugan-San, Shu Gan, and Rou Gan regulated 110, 12, and 407 DEPs, respectively. Compared with Shu Gan or Rou Gan alone, the expression of 22 proteins was additionally changed by Chaihu-Shugan-San treatment, whereas the expression of 323 proteins whose expression was changed by Shu Gan or Rou Gan alone were not changed by Chaihu-Shugan-San treatment. Bioinformatics analysis demonstrated that Chaihu-Shugan-San affected neurotransmitter’s release and transmission cycle (e.g., γ-aminobutyric acid (GABA), glutamate, serotonin, norepinephrine, dopamine, and acetylcholine). GABA release pathway is also targeted by the 22 DEPs. Unexpectedly, only 2 pathways were enriched by the 323 DEPs: Metabolism and Cellular responses to external stimuli. Lastly, the expression of Gad2, Vamp2, and Pde2a was verified by western blotting.

Conclusions: Chaihu-Shugan-San treats depression via multiple targets and pathways, which may include regulations of 110 DEPs and some neurotransmitter’s transmission cycle. Compared with Shu Gan and Rou Gan, the 22 Chaihu-Shugan-San advanced proteins and the affected GABA pathway may be the advantages of Chaihu-Shugan-San compatibility. This research offers data and theory support for the clinical application of Chaihu-Shugan-San.

Importance of oxidative stress in the pathogenesis, diagnosis, and monitoring of patients with neuropsychiatric disorders, a review

Oxidative stress is defined as the persistent imbalance between the activity of toxic reactive forms of both oxygen and nitrogen and the antioxidant defense. In low concentrations, they are essential for the proper functioning of the body. Still, their excessive amount contributes to the damage of the biomolecules, consequently leading to various pathologies of the organism. Due to the lipid-rich brain structure, enormous oxygen consumption, and the lack of a sufficient antioxidant barrier make it highly susceptible to oxidative imbalance. Hence, oxidative stress has been linked to various psychiatric disorders. These diseases include all behavioral, emotional, and cognitive abnormalities associated with a significant impediment to social life. Each of the diseases in question: Alzheimer's disease, schizophrenia, depression, and bipolar disorder, is characterized by excessive oxidative stress. Considerable damages to DNA, RNA, proteins, lipids, and mitochondrial dysfunction, are observed. All conditions show increased lipid peroxidation, which appears to be typical of psychiatric disorders because the brain contains large amounts of these types of molecules. In addition, numerous abnormalities in the antioxidant defense are noted, but the results of studies on the activity of antioxidant enzymes differ significantly. The most promising biomarkers seem to be GSH in Alzheimer's disease as an early-stage marker of the disease and thioredoxin in schizophrenia as a marker for therapy monitoring. Data from the literature are consistent with the decrease in antioxidants such as vitamin C, E, uric acid, albumin, etc. Despite these numerous inconsistencies, it seems that oxidative stress is present in the course of psychiatric diseases. Still, it cannot be conclusively determined whether it is the direct cause of development, a consequence of other abnormalities at the biochemical or molecular level, or the result of the disease itself.

Danzhi Xiaoyao Powder Promotes Neuronal Regeneration by Downregulating Notch Signaling Pathway in the Treatment of Generalized Anxiety Disorder

Background: Generalized anxiety disorder (GAD) is one of the most common types of anxiety disorders with unclear pathogenesis. Our team's previous research found that extensive neuronal apoptosis and neuronal regeneration disorders occur in the hippocampus of GAD rats. Danzhi Xiaoyao (DZXYS) Powder can improve the anxiety behavior of rats, but its molecular mechanism is not well understood. Objective: This paper discusses whether the pathogenesis of GAD is related to the abnormal expression of Notch signal pathway, and whether the anti-anxiety effect of DZXYS promotes nerve regeneration in the hippocampus by regulating the Notch signaling pathway. Methods: The animal model of GAD was developed by the chronic restraint stress and uncertain empty bottle stimulation method. After the model was successfully established, the rats in the model preparation group were divided into the buspirone, DZXYS, DZXYS + DAPT, and model groups, and were administered the corresponding drug intervention. The changes in body weight and food intake of rats were continuously monitored throughout the process. The changes in anxiety behavior of rats were measured by open field experiment and elevated plus-maze test, and morphological changes and regeneration of neurons in the rat hippocampus were observed by HE staining and double immunofluorescence staining. Changes in the expression of key targets of the Notch signaling pathway in the hippocampus were monitored by real-time fluorescence quantitative PCR and western blotting. Results: In this study, we verified that the GAD model was stable and reliable, and found that the key targets of the Notch signaling pathway (Notch1, Hes1, Hes5, etc.) in the hippocampus of GAD rats were significantly upregulated, leading to the increased proliferation of neural stem cells in the hippocampus and increased differentiation into astrocytes, resulting in neuronal regeneration. DZXYS intervention in GAD rats can improve appetite, promote weight growth, and significantly reverse the anxiety behavior of GAD rats, which can inhibit the upregulation of key targets of the Notch signaling pathway, promote the differentiation of neural stem cells in the hippocampus into neurons, and inhibit their differentiation into astrocytes, thus alleviating anxiety behavior. Conclusion: The occurrence of GAD is closely related to the upregulation of the Notch signaling pathway, which hinders the regeneration of normal neurons in the hippocampus, while DZXYS can downregulate the Notch signaling pathway and promote neuronal regeneration in the hippocampus, thereby relieving anxiety behavior.

Targeting inflammation in depression: Ketamine as an anti-inflammatory antidepressant in psychiatric emergency

Major depressive disorder (MDD) is a common psychiatric disorder with multifactorial aetiology and complex pathophysiology. Despite availability of various pharmacological and non-pharmacological therapeutic strategies, treatment resistant depression (TRD) remains a significant challenge with specific concern for those patients with severe depressive symptoms in particular suicidal ideations who require immediate and effective intervention. Inflammation has been widely studied for its association with MDD and treatment response. Ketamine known as a dissociative anaesthetic has a novel rapid-acting antidepressant effect at lower doses. Anti-inflammatory actions of ketamine appear to play a role in mechanisms underlying its antidepressant effects. Considering the rapid antidepressant action of ketamine, this review provides a brief overview of antidepressant properties of ketamine as well as its effects on peripheral and central inflammation to better understand the mechanisms underlying the therapeutic action of ketamine as an anti-inflammatory antidepressant target in psychiatric emergency. Development of effective medications, which act rapidly with dual effect on both inflammation and MDD would be of a significant clinical importance for a successful and personalised treatment of inflammatory-induced TRD and suicidal thoughts and behaviour.

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Anti-inflammatory actions of ketamine play a role in mechanisms underlying its antidepressant effects.

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Ketamine’s dual effect on inflammation and depression is particularly important in treatment of inflammatory-induced TRD and suicidal patients.

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Ketamine affects CNS receptors and pathways, neurotransmitter systems, synaptogenesis, and inflammatory responses.

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Ketamine remains a promising target for treatment of TRD and suicidal thoughts.

Phencynonate hydrochloride exerts antidepressant effects by regulating the dendritic spine density and altering glutamate receptor expression

Phencynonate hydrochloride (PCH) is a drug that crosses the blood-brain barrier. Cellular experiments confirmed that PCH protects against glutamate toxicity and causes only weak central inhibition and limited side effects. As shown in our previous studies, PCH alleviates depression-like behaviours induced by chronic unpredictable mild stress (CUMS). Here we administered PCH at three different doses (4, 8 and 16 mg/kg) to male rats for two continuous days after CUMS and conducted behavioural tests to assess the dose-dependent antidepressant effects of PCH and its effects on the neuroplasticity in the hippocampus and medial prefrontal cortex (mPFC). Meanwhile, we measured the spine density and expression of related proteins to illustrate the mechanism of PCH. PCH treatment (8 mg/kg) significantly alleviated depression-like behaviours induced by CUMS. All doses of PCH treatment reversed the spine loss in prelimbic and CA3 regions induced by CUMS. Kalirin-7 expression was decreased in the hippocampus and mPFC of the CUMS group. The expression of the NR1 and NR2B subunits in the hippocampus, and NR2B in mPFC are increased by CUMS. PCH treatment (8 and 16 mg/kg) reversed all of these changes of Kalirin-7 in PFC and hippocampus, as well as NR1 and NR2B expression in the hippocampus. PCH is expected to be developed as a new type of rapid antidepressant. Its antidepressant effect may be closely related to the modulation of dendritic spine density in the prelimbic and CA3 regions and the regulation of Kalilin-7 and N-methyl-D-aspartic acid receptor levels in the hippocampus.

Multi-omics based strategy for toxicity analysis of acrylamide in Saccharomyces cerevisiae model

Although the toxicity of acrylamide (ACR) has been extensively investigated in different experimental models, its perturbations to multiple nodes of the cellular signaling network have not been systematically associated. In this study, changes at different omics layers in ACR exposed Saccharomyces cerevisiae cells were monitored using a multi-omics strategy. The results of the analysis highlighted the impairment of oxidative-reductive balance, energy metabolism, lipid metabolism, nucleotide metabolism, and ribosome function in yeast cells. Response to acute ACR damage, glutathione synthesis was upregulated, the process of protein degradation was accelerated, and the autophagy flux was initiated. Meanwhile, yeast upregulates gene expression levels of enzymes in carbohydrate metabolism and speeds up the oxidation process of fatty acids to compensate for energy depletion. Importantly, the multi-omics strategy captures features that have rarely been addressed in previous studies on the toxicology of ACR, including blocked de novo nucleotide synthesis, decreased levels of metabolic enzyme cofactors thiamine and D-biotin, increased intracellular concentrations of neurotoxic N-methyl d-aspartic acid and l-glutamic acid, and release of death mediators ceramide. The ACR perturbation network constructed in this work and the discovery of new damage features provide a theoretical basis for subsequent point-to-point toxicological studies.

Novel rapid-acting glutamatergic modulators: Targeting the synaptic plasticity in depression

Major depressive disorder (MDD) is severely prevalent, and conventional monoaminergic antidepressants gradually exhibit low therapeutic efficiency, especially for patients with treatment-resistant depression. A neuroplasticity hypothesis is an emerging advancement in the mechanism of depression, mainly expressed in the glutamate system, e.g., glutamate receptors and signaling. Dysfunctional glutamatergic neurotransmission is currently considered to be closely associated with the pathophysiology of MDD. Biological function, pharmacological action, and signal attributes in the glutamate system both regulate the neural process. Specific functional subunits could be therapeutic targets to explore the novel glutamatergic modulators, which have fast-acting, and relatively sustained antidepressant effects. Here, the present review summarizes the pathophysiology of MDD found in the glutamate system, exploring the role of glutamate receptors and their downstream effects. These convergent mechanisms have prompted the development of other modulators targeting on glutamate system, including N-methyl-d-aspartate receptor antagonists, selective GluN2B-specific antagonists, glycine binding site agents, and regulators of metabotropic glutamate receptors. Relevant researches underly the putative mechanisms of these drugs, which reverse the damage of depression by regulating glutamatergic neurotransmission. It also provides further insight into the mechanism of depression and exploring potential targets for novel agent development.

The Role of the GABAergic System in Diseases of the Central Nervous System

It is well known that the central nervous system (CNS) is a complex neuronal network and its function depends on the balance between excitatory and inhibitory neurons. Disruption of the excitatory/inhibitory (E/I) balance is the main cause for the majority of the CNS diseases. In this review, we will discuss roles of the inhibitory system in the CNS diseases. The GABAergic system as the main inhibitory system, is essential for the appropriate functioning of the CNS, especially as it is engaged in the formation of learning and memory. Many researchers have reported that the GABAergic system is involved in regulating synaptic plasticity, cognition and long-term potentiation. Some clinical manifestations (such as cognitive dysfunctions, attention deficits, etc.) have also been shown to emerge after abnormalities in the GABAergic system accompanied with concomitant diseases, that include Alzheimer's disease (AD), Parkinson's disease (PD), Autism spectrum disorder (ASD), Schizophrenia, etc. The GABAergic system consists of GABA, GABA transporters, GABAergic receptors and GABAergic neurons. Changes in any of these components may contribute to the dysfunctions of the CNS. In this review, we will synthesize studies which demonstrate how the GABAergic system participates in the pathogenesis of the CNS disorders, which may provide a new idea that might be used to treat the CNS diseases.

Perspectives for therapy of treatment-resistant depression

A high proportion of depressed patients fail to respond to antidepressant drug treatment. Treatment-resistant depression (TRD) is a major challenge for the psychopharmacology of mood disorders. Only in the past decade have novel treatments, including deep brain stimulation (DBS) and ketamine, been discovered that provide rapid and sometimes prolonged relief to a high proportion of TRD sufferers. In this review, we consider the current status of TRD from four perspectives: the challenge of developing an appropriate regulatory framework for novel rapidly acting antidepressants; the efficacy of non-pharmacological somatic therapies; the development of an animal model of TRD and its use to understand the neural basis of antidepressant non-response; and the potential for rapid antidepressant action from targets (such as 5-HT_1A receptors) beyond the glutamate receptor.

Ginsenoside Rg1 Prevents PTSD-Like Behaviors in Mice Through Promoting Synaptic Proteins, Reducing Kir4.1 and TNF-α in the Hippocampus

Ginsenoside Rg1 is efficient to prevent or treat mental disorders. However, the mechanisms underlying the effects of ginsenoside Rg1 on post-traumatic stress disorder (PTSD) are still not known. In this study, single-prolonged stress (SPS) regime, as well as injection of lipopolysaccharide (LPS), was used to produce PTSD-like behaviors in C57 mice, and the effects of ginsenoside Rg1 (10, 20, 40 mg/kg/d, ip, for 14 days) on PTSD-like behaviors were evaluated. Our results showed that ginsenoside Rg1 promoted fear extinction and prevented depression-like behaviors in both LPS and SPS models. Importantly, ginsenoside Rg1 alleviated LPS- or SPS-stimulated expression of pro-inflammatory cytokines (IL-1β and TNF-α), activation of astrocytes and microglia, and reduction of hippocampal synaptic proteins (PSD95, Arc, and GluA1). Ginsenoside Rg1 also reduced the increase of hippocampal Kir4.1 and GluN2A induced by PTSD regime. Importantly, reducing hippocampal astroglial Kir4.1 expression promoted fear extinction and improved depression-like behaviors in LPS-treated mice. Additionally, intracerebroventricular injection of TNF-α caused an impairment of fear extinction and promoted Kir4.1 expression in the hippocampus. Together, our study reveals novel protective effects of ginsenoside Rg1 against PTSD-like behaviors in mice, likely via promoting synaptic proteins, reducing Kir4.1 and TNF-α in the hippocampus.

Efficacy of dextromethorphan for the treatment of depression: a systematic review of preclinical and clinical trials

INTRODUCTION

The large percentage of adults with major depressive disorder (MDD) insufficiently responding and/or tolerating conventional monoamine-based antidepressants invites the need for mechanistically novel treatments. Convergent evidence implicates glutamatergic signaling as a potential therapeutic target in MDD.

AREAS COVERED

The synthesis herein of preclinical and clinical studies indicates that dextromethorphan (DXM) is well tolerated and exhibits clinically significant antidepressant effects; DXM combined with bupropion has demonstrated replicated and relatively rapid onset efficacy in adults with MDD. DXM efficacy has been preliminarily reported in adults with bipolar depression. The combination of DXM and bupropion represents a pharmacokinetic and pharmacodynamic synergy which may account for the rapidity of action in MDD.

EXPERT OPINION

The combination of DXM and bupropion is a safe, well tolerated and efficacious treatment option in adults with MDD. Priority questions are whether DXM/bupropion is uniquely effective across discrete domains of psychopathology (e.g. anhedonia, reward processing, general cognitive systems) and/or whether it is able to significantly improve patient-reported outcomes (e.g. quality of life, psychosocial functioning). The availability of ketamine/esketamine and DXM/bupropion instantiates the relevance of glutamate as a treatment target in MDD. Studies in bipolar depression with DXM/bupropion are warranted as well as in MDD with suicidality.

Chronic ethanol exposure induced depressive-like behavior in male C57BL/6 N mice by downregulating GluA1

Chronic ethanol exposure can increase the risk of depression. The α-amino-3‑hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor is a key factor in depression and its treatment. The study was conducted to investigate the depressive-like behavior induced by chronic ethanol exposure in mice and to explore the mechanism in cells. To establish the chronic ethanol exposure mouse model, male C57BL/6 N mice were administered 10% (m/V) and 20% (m/V) ethanol as the only choice for drinking for 60 days, 90 days and 180 days. Depressive-like behavior in mice was confirmed by the forced swimming test (FST). Ethanol-induced changes in the mouse hippocampus were indicated by Western blotting, qPCR and Fluoro-Jade C (FJC) staining. We confirmed that 90- and 180-day ethanol exposure can lead to depressive-like mouse behavior, cell apoptosis, neuronal degeneration, a reduction in GluA1 and brain-derived neurotrophic factor (BDNF) expression, and an increase in IL-6 and IL-1β in the mouse hippocampus. GluA1 silencing and overexpression models of SH-SY5Y cells were established for further investigation. The cells were treated with 100 mM and 200 mM ethanol for 24 h. Ethanol exposure decreased cell viability and the expression of BDNF and increased the cell apoptosis rate and the expression of BAX, cleaved caspase-3, IL-1β and IL-6. GluA1 silencing aggravated ethanol-induced changes in cell viability and apoptosis and the expression of BDNF, BAX and cleaved caspase-3, and GluA1 overexpression attenuated these changes. Neither the silencing nor overexpression of GluA1 had an effect on ethanol-induced increases in IL-1β and IL-6. Our results indicated that chronic ethanol exposure induced depressive-like behavior in male C57BL/6 N mice by downregulating GluA1 expression.

Depression: Biological markers and treatment

Nowadays depression is considered as a systemic illness with different biological mechanisms involved in its etiology, including inflammatory response, hypothalamic-pituitary-adrenal (HPA) axis dysregulation and neurotransmitter and neurotrophic systems imbalance. Novel "omics" approaches, such as metabolomics and glycomics provide information about altered metabolic pathways and metabolites, as well as disturbances in glycosylation processes affected by or causing the development of depression. The clinical diagnosis of depression continues to be established based on the presence of the specific symptoms, but due to its heterogeneous underlying biological background, that differs according to the disease stage, there is an unmet need for treatment response biomarkers which would facilitate the process of appropriate treatment selection. This paper provides an overview of the role of major stress response system, the HPA axis, and its dysregulation in depression, possible involvement of neurotrophins, especially brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor and insulin-like growth factor-1, in the development of depression. Article discusses how activated inflammation processes and increased cytokine levels, as well as disturbed neurotransmitter systems can contribute to different stages of depression and could specific metabolomic and glycomic species be considered as potential biomarkers of depression. The second part of the paper includes the most recent findings about available medical treatment of depression. The described biological factors impose an optimistic conclusion that they could represent easy obtainable biomarkers potentially predicting more personalized treatment and diagnostic options.

Modulation of DNA Methylation and Gene Expression in Rodent Cortical Neuroplasticity Pathways Exerts Rapid Antidepressant-Like Effects

BACKGROUND

Stress increases DNA methylation, primarily a suppressive epigenetic mechanism catalyzed by DNA methyltransferases (DNMT), and decreases the expression of genes involved in neuronal plasticity and mood regulation. Despite chronic antidepressant treatment decreases stress-induced DNA methylation, it is not known whether inhibition of DNMT would convey rapid antidepressant-like effects.

AIM

This work tested such a hypothesis and evaluated whether a behavioral effect induced by DNMT inhibitors (DNMTi) corresponds with changes in DNA methylation and transcript levels in genes consistently associated with the neurobiology of depression and synaptic plasticity (BDNF, TrkB, 5-HT1A, NMDA, and AMPA).

METHODS

Male Wistar rats received intraperitoneal (i.p.) injection of two pharmacologically different DNMTi (5-AzaD 0.2 and 0.6 mg/kg or RG108 0.6 mg/kg) or vehicle (1 ml/kg), 1 h or 7 days before the learned helplessness test (LH). DNA methylation in target genes and the correspondent transcript levels were measured in the hippocampus (HPC) and prefrontal cortex (PFC) using meDIP-qPCR. In parallel separate groups, the antidepressant-like effect of 5-AzaD and RG108 was investigated in the forced swimming test (FST). The involvement of cortical BDNF-TrkB-mTOR pathways was assessed by intra-ventral medial PFC (vmPFC) injections of rapamycin (mTOR inhibitor), K252a (TrkB receptor antagonist), or vehicle (0.2 μl/side).

RESULTS

We found that both 5-AzaD and RG108 acutely and 7 days before the test decreased escape failures in the LH. LH stress increased DNA methylation and decreased transcript levels of BDNF IV and TrkB in the PFC, effects that were not significantly attenuated by RG108 treatment. The systemic administration of 5-AzaD (0.2 mg/kg) and RG108 (0.2 mg/kg) induced an antidepressant-like effect in FST, which was, however, attenuated by TrkB and mTOR inhibition into the vmPFC.

CONCLUSION

These findings suggest that acute inhibition of stress-induced DNA methylation promotes rapid and sustained antidepressant effects associated with increased BDNF-TrkB-mTOR signaling in the PFC.

Bacterial Metabolites of Human Gut Microbiota Correlating with Depression

Depression is a global threat to mental health that affects around 264 million people worldwide. Despite the considerable evolution in our understanding of the pathophysiology of depression, no reliable biomarkers that have contributed to objective diagnoses and clinical therapy currently exist. The discovery of the microbiota-gut-brain axis induced scientists to study the role of gut microbiota (GM) in the pathogenesis of depression. Over the last decade, many of studies were conducted in this field. The productions of metabolites and compounds with neuroactive and immunomodulatory properties among mechanisms such as the mediating effects of the GM on the brain, have been identified. This comprehensive review was focused on low molecular weight compounds implicated in depression as potential products of the GM. The other possible mechanisms of GM involvement in depression were presented, as well as changes in the composition of the microbiota of patients with depression. In conclusion, the therapeutic potential of functional foods and psychobiotics in relieving depression were considered. The described biomarkers associated with GM could potentially enhance the diagnostic criteria for depressive disorders in clinical practice and represent a potential future diagnostic tool based on metagenomic technologies for assessing the development of depressive disorders.

Similarities Between Depression and Neurodegenerative Diseases: Pathophysiology, Challenges in Diagnosis and Treatment Options

Depressive disorder and neurodegenerative diseases are two different clinical entities. Depression is a common psychiatric disorder in the general population. However, when present concomitantly with neurodegenerative disorders, its diagnosis becomes challenging. In many cases, patients remain undiagnosed and hence, untreated, worsening the prognosis of the neurodegenerative diseases and impairing the quality of life. One of the possible reasons for the difficulties in diagnosis in such cases is that both conditions affect the central nervous system, so there might be an overlap of symptoms leading to a missed diagnosis of depression in a neurodegenerative disease patient and vice versa. Symptoms such as irritability, apathy, and decreased cognition are common to both types of disorders. Some neurodegenerative diseases, especially Alzheimer's disease, can initially present as a depressive prodrome. This may cause a difficulty in differentiating between these two conditions and a diagnosis of either conditions may be missed; hence an opportunity for timely intervention and improved outcomes is missed. An approach towards analyzing and comparing the pathological mechanisms common to both disease types will create a better understanding of depression and neurodegenerative diseases, identify their similarities, and develop improved clinical criteria to help clinicians make a timely diagnosis of these conditions present together. In the present review, various studies related to common pathological links, concomitant diagnosis challenges, and ongoing research about different treatment options are discussed.