Associations Among Monoamine Neurotransmitter Pathways, Personality Traits, and Major Depressive Disorder

Mobilization of the innate immune response by a specific immunostimulant β-glucan confers resistance to chronic stress-induced depression-like behavior by preventing neuroinflammatory responses

Pre-stimulation of the innate immune response is an effective strategy to prevent depression-like phenotypes in animals. However, the use of conventional immunostimulants may cause adverse effects. Therefore, the search for agents that stimulate the innate immune response but do not induce a pro-inflammatory response could be a new research direction for the prevention of depression. β-glucan is a polysaccharide from Saccharomyces cerevisiae with unique immunomodulatory activity in microglia without eliciting a pro-inflammatory response that could lead to tissue damage. This suggests that β-glucan may be a suitable drug that can be used to prevent depression-like phenotypes. Our results showed that a single injection of β-glucan 1 day before stress exposure at a dose of 10 or 20 mg/kg, but notat a dose of 5 mg/kg, prevented depression-like behavior in mice treated with chronic unpredictable stress (CUS). This effect of β-glucan disappeared when the time interval between β-glucan and stress was extended from 1 day or 5 days to 10 days, which was rescued by a second injection 10 days after the first injection or by a repeated injection (4×, once daily) 10 days before stress exposure. A single β-glucan injection (20 mg/kg) 1 day before stress exposure prevented the CUS-induced increase in brain pro-inflammatory cytokines, and inhibition of the innate immune response by minocycline (40 mg/kg) abolished the preventive effect of β-glucan on CUS-induced depression-like behaviors and neuroinflammatory responses. These results suggest that β-glucan may prevent chronic stress-induced depression-like phenotypes and neuroinflammatory responses by stimulating the innate immune response.

Mechanistic interplay of different mediators involved in mediating the anti-depressant effect of isoflavones

Depression is one of the most prevalent severe CNS disorders, which negatively affects social lives, the ability to work, and the health of people. As per the World Health Organisation (WHO), it is a psychological disorder that is estimated to be a leading disease by 2030. Clinically, various medicines have been formulated to treat depression but they are having a setback due to their side effects, slow action, or poor bioavailability. Nowadays, flavonoids are regarded as an essential component in a variety of nutraceutical, pharmaceutical and medicinal. Isoflavones are a distinctive and important subclass of flavonoids that are generally obtained from soybean, chickpeas, and red clover. The molecules of this class have been extensively explored in various CNS disorders including depression and anxiety. Isoflavones such as genistein, daidzein, biochanin-A, formononetin, and glycitein have been reported to exert an anti-depressant effect through the modulation of different mediators. Fatty acid amide hydrolase (FAAH) mediated depletion of anandamide and hypothalamic-pituitary-adrenal (HPA) axis-mediated modulation of brain-derived neurotrophic factor (BDNF), monoamine oxidase (MAO) mediated depletion of biogenic amines and inflammatory signaling are the important underlying pathways leading to depression. Upregulation in the levels of BDNF, anandamide, antioxidants and monoamines, along with inhibition of MAO, FAAH, HPA axis, and inflammatory stress are the major modulations produced by different isoflavones in the observed anti-depressant effect. Therefore, the present review has been designed to explore the mechanistic interplay of various mediators involved in mediating the anti-depressant action of different isoflavones.

Preparation of NIn-Methyl-6-[18F]fluoro- and 5-Hydroxy-7-[18F]fluorotryptophans as Candidate PET-Tracers for Pathway-Specific Visualization of Tryptophan Metabolism

Tryptophan (Trp) is an essential proteinogenic amino acid and metabolic precursor for several signaling molecules that has been implicated in many physiological and pathological processes. Since the two main branches of Trp metabolism-serotonin biosynthesis and kynurenine pathway-are differently affected by a variety of neurological and neoplastic diseases, selective visualization of these pathways is of high clinical relevance. However, while positron emission tomography (PET) with existing probes can be used for non-invasive assessment of total Trp metabolism, optimal imaging agents for pathway-specific PET imaging are still lacking. In this work, we describe the preparation of two 18F-labeled Trp derivatives, NIn-methyl-6-[18F]fluorotryptophan (NIn-Me-6-[18F]FTrp) and 5-hydroxy-7-[18F]fluorotryptophan (5-HO-7-[18F]FTrp). We also report feasible synthetic routes for the preparation of the hitherto unknown boronate radiolabeling precursors and non-radioactive reference compounds. Under optimized conditions, alcohol-enhanced Cu-mediated radiofluorination of the respective precursors afforded NIn-Me-6-[18F]FTrp and 5-HO-7-[18F]FTrp as application-ready solutions in radiochemical yields of 45 ± 7% and 29 ± 4%, respectively. As such, our work provides access to two promising candidate probes for pathway-specific visualization of Trp metabolism in amounts sufficient for their preclinical evaluation.

Ethyl pyruvate prevents long-term stress-induced cognitive decline and modulates Akt/GSK-3β signaling

Stress is an inevitable part of life and, simultaneously, a stimulus that can trigger various neuropsychiatric disorders. Therefore, proper stress management is essential for maintaining a healthy life. In this study, we investigated the suppression of stress-induced cognitive deficit by controlling changes in synaptic plasticity caused by stress and confirmed that ethyl pyruvate (EP) has such an effect. Corticosterone, a stress hormone, suppresses long-term potentiation (LTP) in mouse acute hippocampal slices. EP blocked the LTP inhibitory effect of corticosterone by regulating GSK-3β function. Restraint stress for 2 weeks increased the anxiety levels and caused the cognitive decline in the experimental animals. Administration of EP for 14 days did not affect the increase in anxiety caused by stress but improved cognitive decline caused by stress. In addition, the decrease in neurogenesis and synaptic function deficits in the hippocampus, which cause of cognitive decline due to stress, were improved by EP administration. These effects appear via regulation of Akt/GSK-3β signaling, as in in vitro studies. These results suggest that EP prevents stress-induced cognitive decline through the modulation of Akt/GSK-3β-mediated synaptic regulation.

Exploratory genome-wide analyses of cortical inhibition, facilitation, and plasticity in late-life depression

Late-life depression (LLD) is a heterogenous mood disorder influenced by genetic factors. Cortical physiological processes such as cortical inhibition, facilitation, and plasticity may be markers of illness that are more strongly associated with genetic factors than the clinical phenotype. Thus, exploring the relationship between genetic factors and these physiological processes may help to characterize the biological mechanisms underlying LLD and improve diagnosis and treatment selection. Transcranial magnetic stimulation (TMS) combined with electromyography was used to measure short interval intracortical inhibition (SICI), cortical silent period (CSP), intracortical facilitation (ICF), and paired associative stimulation (PAS) in 79 participants with LLD. We used exploratory genome-wide association and gene-based analyses to assess for genetic correlations of these TMS measures. MARK4 (which encodes microtubule affinity-regulating kinase 4) and PPP1R37 (which encodes protein phosphatase 1 regulatory subunit 37) showed genome-wide significant association with SICI. EGFLAM (which encodes EGF-like fibronectin type III and laminin G domain) showed genome-wide significant association with CSP. No genes met genome-wide significant association with ICF or PAS. We observed genetic influences on cortical inhibition in older adults with LLD. Replication with larger sample sizes, exploration of clinical phenotype subgroups, and functional analysis of relevant genotypes is warranted to better characterize genetic influences on cortical physiology in LLD. This work is needed to determine whether cortical inhibition may serve as a biomarker to improve diagnostic precision and guide treatment selection in LLD.

Gut Biome and Mental Health: Do Probiotics Work?

Mental health conditions have been linked closely to an imbalance of microbiota in the gut, leading to disruption of the microbiome (dysbiosis). Several neurotransmitters, such as GABA (gamma-aminobutyric acid), serotonin, and glutamate, are produced in the gut, which are associated with anxiety and depressive symptoms. Mental health and the gut have been linked closely, and many mental illnesses have been associated with gut dysbiosis. Probiotics are marketed to improve gut health, act as mood enhancers, and be effective in reducing stress as unregulated over-the-counter supplements. Given healthcare disparities and patient-doctor gaps across the globe, this review aims to appraise the literature on probiotics for the prevention and treatment of mental disorders. PubMed and Google Scholar databases were searched till March 2023 using the MeSH words "prebiotics," "probiotics," "synbiotics," and "psychobiotics." Out of 207 studies, 26 studies met the inclusion criteria and were included in the review. Studies suggest probiotics could be an effective and economical adjunct therapy; however, due to weak study design and low power, the results are inconclusive. Their use is not without risks, and healthcare providers need close supervision until more robust longitudinal studies are conducted to appraise their efficacy and safety profiles.

Antidepressant effects of p-coumaric acid isolated from Vaccinium bracteatum leaves extract on chronic restraint stress mouse model and antagonism of serotonin 6 receptor in vitro

BACKGROUND

Vaccinium bracteatum Thunb. leaves (VBL) are used in traditional herbal medicines to treat various biological diseases. p-coumaric acid (CA), the main active component of VBL, has neuroprotective effects against corticosterone-induced damage in vitro. However, the effects of CA on immobility induced by chronic restraint stress (CRS) in a mouse model and 5-HT receptor activity have not been investigated.

HYPOTHESIS/PURPOSE

We investigated the antagonistic effects of VBL, NET-D1602, and the three components of Gαs protein-coupled 5-HT receptors. Additionally, we identified the effects and mechanism of action of CA, the active component of NET-D1602, in the CRS-exposed model.

METHODS

For in vitro analyses, we used 1321N1 cells stably expressing human 5-HT₆ receptors and CHO-K1 expressing human 5-HT₄ or 5-HT₇ receptors cell lines to study the mechanism of action. For in vivo analyses, CRS-exposed mice were orally administered CA (10, 50, or 100 mg/kg) daily for 21 consecutive days. The effects of CA were analyzed by assessing behavioral changes using a forced swim test (FST), measuring levels of hypothalamic-pituitary-adrenal (HPA) axis-related hormones in ntial therapeutic effects as 5-HT6 receptor antagonists for neurodegenerative diseases and depressioserum, and acetylcholinesterase (AChE), monoamines, including 5-HT, dopamine, and norepinephrine, using enzyme-linked immunosorbent assay kits. The underlying molecular mechanisms of the serotonin transporter (SERT), monoamine oxidase A (MAO-A), and extracellular signal-regulated kinase (ERK)/protein kinase B (Akt)/mTORC1 signaling were detected using western blotting.

RESULTS

CA was confirmed to be an active component in the antagonistic effects of NET-D1602 on 5-HT₆ receptor activity through decreases in cAMP and ERK1/2 phosphorylation. Moreover, CRS-exposed mice treated with CA showed a significantly reduced immobility time in the FST. CA also significantly decreased corticosterone, corticotropin-releasing hormone (CRH), and adrenocorticotropic hormone (ACTH) levels. CA enhanced 5-HT, dopamine, and norepinephrine levels in the hippocampus (HC) and prefrontal cortex (PFC) but decreased MAO-A and SERT protein levels. Similarly, CA significantly upregulated the ERK, Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), Akt/mTOR/p70S6K/S6 signaling pathways in both HC and the PFC.

CONCLUSION

CA contained in NET-D1602 may play the antidepressant effects against CRS-induced depression-like mechanism and the selective antagonist effect of 5-HT₆ receptor.

Naringenin and apigenin ameliorates corticosterone-induced depressive behaviors

Background

Depression is a common kind of mental illness, and it becomes the main health burden in the world.

Purpose

The aim of this study was to investigate the antidepressant effects of naringin and apigenin isolated from Chrysanthemum morifolium Ramatis.

Methods

Firstly, 20 mg/kg corticosterone (CORT) was injected into mice to establish an in vivo model of depression. After treated with different dosages of naringenin and apigenin for 3 weeks, the mice underwent a series of behavioral experiments. Following this, all mice were sacrificed and biochemical analyses were performed. Subsequently, CORT (500 μM) induced PC12 cells was used as an in vitro model of depression, and lipopolysaccharide (LPS) (1 μg ml^-1) induced N9 microglia cells was used as an in vitro model of neuroinflammation in N9 microglia cells, to investigate the neuroprotective mechanisms of naringenin and apigenin.

Results

Results showed that the naringenin and apigenin treatment ameliorated CORT-induced sucrose preference decrease and immobility time increase, elevated the 5-hydroxytryptamine(5-HT), dopamine (DA) and norepinephrine (NE) levels, and enhanced the cAMP-response element binding protein (CREB) and brain derived neurotrophic factor (BDNF) protein expressions in the hippocampus. The results showed that the naringenin and apigenin treatment improved the PC-12 cell viability through reducing apoptosis rate induced by CORT. Furthermore, naringenin and apigenin were able to inhibit the activation of N9 cells after LPS induction, and shift microglia from proinflammatory M1 microglia toward anti-inflammatory M2 microglia, as evidenced by the decreased ratio of M1 type microglia marker CD86 and M2 type microglia marker CD86.

Conclusion

These results suggested that naringenin and apigenin may improve depressive behaviors through promoting BDNF and inhibiting neuroinflammation and neuronal apoptosis.

Flavonols in Action: Targeting Oxidative Stress and Neuroinflammation in Major Depressive Disorder

Major depressive disorder is one of the most common mental illnesses that highly impairs quality of life. Pharmacological interventions are mainly focused on altered monoamine neurotransmission, which is considered the primary event underlying the disease's etiology. However, many other neuropathological mechanisms that contribute to the disease's progression and clinical symptoms have been identified. These include oxidative stress, neuroinflammation, hippocampal atrophy, reduced synaptic plasticity and neurogenesis, the depletion of neurotrophic factors, and the dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis. Current therapeutic options are often unsatisfactory and associated with adverse effects. This review highlights the most relevant findings concerning the role of flavonols, a ubiquitous class of flavonoids in the human diet, as potential antidepressant agents. In general, flavonols are considered to be both an effective and safe therapeutic option in the management of depression, which is largely based on their prominent antioxidative and anti-inflammatory effects. Moreover, preclinical studies have provided evidence that they are capable of restoring the neuroendocrine control of the HPA axis, promoting neurogenesis, and alleviating depressive-like behavior. Although these findings are promising, they are still far from being implemented in clinical practice. Hence, further studies are needed to more comprehensively evaluate the potential of flavonols with respect to the improvement of clinical signs of depression.

Ketamine as a therapeutic agent in major depressive disorder and posttraumatic stress disorder: Potential medicinal and deleterious effects

Major depressive disorder (MDD) and posttraumatic stress disorder (PTSD) are the most common causes of emotional distress that impair an individual's quality of life. MDD is a chronic mental illness that affects 300 million people across the world. Clinical manifestations of MDD include fatigue, loss of interest in routine tasks, psychomotor agitation, impaired ability to focus, suicidal ideation, hypersomnolence, altered psychosocial functioning, and appetite loss. Individuals with depression also demonstrate a reduced behavioral response while experiencing pleasure, a symptom known as anhedonia. Like MDD, PTSD is a prevalent and debilitating psychiatric disorder resulting from a traumatic incident such as sexual assault, war, severe accident, or natural disaster. Symptoms such as recalling event phases, hypervigilance, irritability, and anhedonia are common in PTSD. Both MDD and PTSD pose enormous socioeconomic burdens across the globe. The search for effective treatment with minimal side effects is still ongoing. Ketamine is known for its anesthetic and analgesic properties. Psychedelic and psychotropic effects of ketamine have been found on the nervous system, which highlights its toxicity. In this article, the effectiveness of ketamine as a potential therapeutic for PTSD and MDD along with its mechanisms of action, clinical trials, and possible side effects have been discussed.

Role of the Intestinal Microbiota in the Genesis of Major Depression and the Response to Antidepressant Drug Therapy: A Narrative Review

A major depressive disorder is a serious mental illness characterized by a pervasive low mood that negatively concerns personal life, work life, or education, affecting millions of people worldwide. To date, due to the complexity of the disease, the most common and effective treatments consist of a multi-therapy approach, including psychological, social, and pharmacological support with antidepressant drugs. In general, antidepressants are effective in correcting chemical imbalances of neurotransmitters in the brain, but recent evidence has underlined the pivotal role of gut microbiota (GM) also in the regulation of their pharmacokinetics/pharmacodynamics, through indirect or direct mechanisms. The study of these complex interactions between GM and drugs is currently under the spotlight, and it has been recently named "pharmacomicrobiomics". Hence, the purpose of this review is to summarize the contribution of GM and its metabolites in depression, as well as their role in the metabolism and activity of antidepressant drugs, in order to pave the way for the personalized administration of antidepressant therapies.

Understanding the Connection between Gut Homeostasis and Psychological Stress

Long-term exposure to adverse life events that provoke acute or chronic psychological stress (hereinafter "stress") can negatively affect physical health and even increase susceptibility to psychological illnesses, such as anxiety and depression. As a part of the hypothalamic-pituitary-adrenal axis, corticotropin-releasing factor (CRF) released from the hypothalamus is primarily responsible for the stress response. Typically, CRF disrupts the gastrointestinal system and leads to gut microbiota dysbiosis, thereby increasing risk of functional gastrointestinal diseases, such as irritable bowel syndrome. Furthermore, CRF increases oxidative damage to the colon and triggers immune responses involving mast cells, neutrophils, and monocytes. CRF even affects the differentiation of intestinal stem cells (ISCs), causing enterochromaffin cells to secrete excessive amounts of 5-hydroxytryptamine (5-HT). Therefore, stress is often accompanied by damage to the intestinal epithelial barrier function, followed by increased intestinal permeability and bacterial translocation. There are multi-network interactions between the gut microbiota and stress, and gut microbiota may relieve the effects of stress on the body. Dietary intake of probiotics can provide energy for ISCs through glycolysis, thereby alleviating the disruption to homeostasis caused by stress, and it significantly bolsters the intestinal barrier, alleviates intestinal inflammation, and maintains endocrine homeostasis. Gut microbiota also directly affect the synthesis of hormones and neurotransmitters, such as CRF, 5-HT, dopamine, and norepinephrine. Moreover, the Mediterranean diet enhances the stress resistance to some extent by regulating the intestinal flora. This article reviews recent research on how stress damages the gut and microbiota, how the gut microbiota can improve gut health by modulating injury due to stress, and how the diet relieves stress injury by interfering with intestinal microflora. This review gives insight into the potential role of the gut and its microbiota in relieving the effects of stress via the gut-brain axis.

Personality as a basis for antidepressant selection for patients with depression: A two-point outcome study at 4 and 8 weeks

BACKGROUND

The treatment course for depression is multifactorial, and the gold standard method for antidepressant selection remains unclear. Therefore, we focused on patients' personality as a possible indicator of the treatment response to mirtazapine and selective serotonin reuptake inhibitors (SSRIs) and whether it can contribute to antidepressant selection.

METHODS

One hundred one patients with major depressive disorder were randomized at baseline to receive either mirtazapine or SSRI treatment. Their personality was measured using the NEO Five-Factor Inventory at baseline, and depressive symptoms were evaluated using the Hamilton Rating Scale for Depression at baseline and 4 and 8 weeks. Stepwise multivariable logistic regression and receiver operating characteristic analyses were performed to determine the association of personality traits with remission and better antidepressant selection.

RESULTS

Neuroticism had the substantial influence on remission at 4 and 8 weeks among the entire sample. The cutoff T-score of neuroticism for predicting remission at 4 weeks was 62.5. The patients with moderate neuroticism (scores below the cutoff) were more likely to experience remission after 4-week mirtazapine treatment (remission rate: 73.7 %) than after SSRI treatment (40.0 %); those with high neuroticism (scores above the cutoff) were more likely to experience remission after 8-week SSRI treatment (74.1 %) than after mirtazapine treatment (35.7 %).

LIMITATIONS

The small sample size increased the confidence intervals.

CONCLUSIONS

The treatment response of the patients with depression differed according to the type of antidepressants and degree of neuroticism. Measuring personality traits at treatment initiation may help in selecting better antidepressants and predicting the time to remission.

Morin attenuates neurobehavioural deficits, hippocampal oxidative stress, inflammation, and apoptosis in rats co-exposed to bisphenol S and diethyl phthalate

Endocrine-disrupting pollutants (EDPs) remain pervasive in the environment. Bisphenol S (BPS) and diethyl phthalates (DEP) are commonly used to replace the more toxic EDPs. However, it is unclear if they induce neurotoxicity, like their predecessors. Morin possesses relevant neuro-pharmacological activities. Hence, we sought to evaluate the protective effects of morin against the neurotoxic effects previously reported for EDPs. Male Wistar rats were exposed to a mixture of BPS and DEP (MBD) and treated with morin for 21 days. Behavioural assessments were conducted, and the hippocampal tissues were processed for analysis. Rats exposed to MBD presented anxiety-like behaviours, impaired cognitive and motor functions compared to the control group. MBD exposure induced hyperactivity of neurosignalling enzymes (AChE, ADA, MAO-A) and depleted hippocampal antioxidants (SOD, CAT, GPx, and GSH). MBD exposure increased calcium levels and inhibited total Ca²⁺-ATPase activity. Levels of reactive species (NO and H₂O₂) and oxidative damage markers (MDA and AOPP) were significantly (P < 0.05) elevated compared to control. The hippocampal expressions of IL-1β, TNFα, BAX, and APAF-1 in the MBD-exposed rats were significantly higher compared to control. Correspondingly, NF-κB and caspase-3 pathways were activated in the hippocampus of MBD-exposed rats, while the expressions of IL-10 and BDNF were repressed. However, co-treatment with morin improved the neurobehavioral outcomes, alleviated the hyperactivity of neurosignalling enzymes, while suppressing hippocampal oxidative stress, inflammation, and apoptosis. Histological and stereological evaluations supported these findings. In conclusion, co-exposure to BPS and DEP elicit similar neurotoxic outcomes as their predecessors, while morin confers marked protection against these outcomes.

Prevention and treatment of natural products from Traditional Chinese Medicine in depression: Potential targets and mechanisms of action

The molecular pathology involved in the development of depression is complex. Many signaling pathways and transcription factors have been demonstrated to display crucial roles in the process of depression occurrence and development. The multi-components and multi-targets of Traditional Chinese Medicine (TCM) are uniquely advantageous in the prevention and treatment of chronic diseases. This review summarizes the pharmacological regulations of natural products from TCM in the prevention and treatment of depression from the aspects of transcription factors (CREB, NF-κB, Nrf2) and molecular signaling pathways (BDNF-TrkB, MAPK, GSK-3β, TLR-4).

Auditory event-related potentials in separating patients with depressive disorders and non-depressed controls: A narrative review

This narrative review brings together the findings regarding the differences in the auditory event-related potentials (ERPs) between patients with depressive disorder and non-depressed control subjects. These studies' results can inform us of the possible alterations in sensory-cognitive processing in depressive disorders and the potential of using these ERPs in clinical applications. Auditory P3, mismatch negativity (MMN) and loudness dependence of auditory evoked potentials (LDAEP) were the subjects of the investigation. A search in PubMed yielded 84 studies. The findings of the reviewed studies were not highly consistent, but some patterns could be identified. For auditory P3b, the common findings were attenuated amplitude and prolonged latency among depressed patients. Regarding auditory MMN, especially the amplitude of duration deviance MMN was commonly attenuated, and the amplitude of frequency deviance MMN was increased in depressed patients. In LDAEP studies, generally, no differences between depressed patients and non-depressed controls were reported, although some group differences concerning specific depression subtypes were found. This review posits that future research should investigate whether certain stimulus conditions are particularly efficient at separating depressed and non-depressed participant groups. Future studies should contrast responses in different subpopulations of depressed patients, as well as different clinical groups (e.g., depressive disorder and anxiety disorder patients), to investigate the specificity of the auditory ERP alterations for depressive disorders.

Effect and neural mechanisms of the transcutaneous vagus nerve stimulation for relapse prevention in patients with remitted major depressive disorder: protocol for a longitudinal study

INTRODUCTION

After the first episode, patients with remitted major depressive disorder (MDD) have a 60% chance of experiencing a second episode. There are currently no accepted, effective methods to prevent the recurrence of MDD in remission. Transcutaneous vagus nerve stimulation (taVNS) is a non-invasive, safe and economical approach based on the efficacy of VNS in improving clinical depression symptoms. This clinical trial will study the efficacy of taVNS in preventing MDD relapse and investigate the underlying mechanisms of this.

METHODS AND ANALYSIS

We will conduct a multicentre, randomised, patient-blinded and evaluators double-blinded trial. We will randomise 90 eligible participants with recurrent MDD in remission in a 1:1 ratio into a real or sham taVNS group. All participants will be given six biopsychosocial assessments: proinflammatory cytokines, serum monoamine neurotransmitters, cognition, affective neuropsychology, multimodal neuroimaging and endocrinology. After the baseline measurements, all participants will be given corresponding interference for 6 months and then complete a 1-year follow-up. The assessments will be performed three times: at baseline, post-treatment and at the end of 1-year follow-up (except for multimodal MRI scanning, which will be conducted at the first two assessments only). Change in 17-item Hamilton Depression Rating Scale scores for MDD is the primary outcome parameter.

ETHICS AND DISSEMINATION

The study protocol was approved by the Medical Ethical Committee of Beijing Hospital of Traditional Chinese Medicine on 18 January 2019 (2018BL-076). The trial results will be published in peer-reviewed journals and at conferences.

TRIAL REGISTRATION NUMBER

ChiCTR1900022618.

Monoamine neurotransmitters and mood swings: a dynamical systems approach

Serotonin, dopamine and norepinephrine are monoamine neurotransmitters that modulate our mood state. Hence, imbalances in the levels of these neurotransmitters have been linked to the incidence of several psychiatric disorders. Here, a mathematical model written in terms of ordinary differential equations is proposed to represent the interaction of these three neurotransmitters. It is analytically and numerically shown that this model can experience a Hopf bifurcation. Thus, by varying a parameter value, the neurotransmitter levels can change from a steady state to an oscillatory behavior, which may be at least a partial explanation of the mood swings observed in depressed people.

Post-Stroke Depression: Prevalence, Associated Factors, and Relationship to Disability in a Tertiary Care Center in Sri Lanka

Background and Objectives The prevalence of stroke in urban Sri Lanka is estimated at 10.4 per 1000 and is expected to rise. Post-stroke depression (PSD) is an independent predictor of poor long-term outcomes. It leads to suboptimal rehabilitation, decreased quality of life, and increased mortality and is under-recognized. The main objectives of this study were to estimate the prevalence of depression in stroke, assess factors associated with PSD, and assess the relationship of PSD to disability.

Materials and Methods A descriptive cross-sectional study was conducted at the Neurology and Medical Ward, National Hospital of Sri Lanka. Non-probability, consecutive sampling was used to collect data from patients with ischemic stroke admitted from January 2019 to January 2020. Patients with significant pre-existing depression, cognitive impairment, and language deficits were excluded. A structured, pre-tested interviewer-administered questionnaire was used to assess the prevalence and associated factors of PSD. Beck's Depression Inventory (BDI) was administered 3 months following the stroke to screen for depression. Modified Rankin Score (MRS) was used to assess disability on admission, discharge, and at 3 months.

Results Eighty-one stroke patients were screened. The mean age was 66.6 years (±standard deviation [SD]: 12.5). Male:female ratio was 1.2:1. Depression at 3 months of follow-up was observed in 35.8% (95% confidence interval [CI]: 25.4–47.2%) of participants. Following bivariate analysis, large vessel stroke (p < 0.001), cortical stroke (p < 0.001), frontal lobe lesions (p < 0.001), history of past stroke (p = 0.014), and sexual dysfunction (p = 0.026) were associated with increased risk of PSD. The odds of a person with severe disability developing PSD was 7.9 times more than a person with a less severe disability at discharge from hospital and at 3 months of follow-up (odds ratio [OR] =7.9; 95% CI: 2.7–23.3, p = 0.000).

Conclusions PSD occurs in one-third of strokes, keeping with previous studies. The risk of having PSD is higher among patients with severe disabilities. The difference in risk factors identified compared with previous studies can be attributable to differences in methodology. Identifying risk factors for post-stroke depression is essential to mitigate the poor outcome.

A graphene-based electrochemical flow analysis device for simultaneous determination of dopamine, 5-hydroxytryptamine, and melatonin

A graphene-based electrochemical flow analysis device for simultaneous determination of dopamine, 5-hydroxytryptamine, and melatonin.

Methamphetamine, Neurotransmitters and Neurodevelopment

Methamphetamine (MA), as massively abused psychoactive stimulant, has been associated with many neurological diseases. It has various potent and neurotoxic properties. There are many mechanisms of action that contribute to its neurotoxic and degenerative effects, including excessive neurotransmitter (NEU) release, blockage of NEU uptake transporters, degeneration of NEU receptors, process of oxidative stress etc. MA intoxication is caused by blood-brain barrier disruption resulted from MA-induced oxidation stress. In our laboratory we constantly work on animal research of MA. Our current interest is to investigate processes of MA-induced alteration in neurotransmission, especially during development of laboratory rat. This review will describe current understanding in role of NEUs, which are affected by MA-induced neurotoxicity caused by altering the action of NEUs in the central nervous system (CNS). It also briefly brings information about NEUs development in critical periods of development.

[Features of the parameters of hemodynamics and vascular tone of the brain in patients with depressive disorders]

OBJECTIVE

To study the features of hemodynamics and vascular tone of the brain in patients with depressive disorders.

MATERIAL AND METHODS

Fifty-four patients with depressive disorders and 54 conditionally healthy individuals were examined. The study of hemodynamics and vascular tone of the brain was carried out using rheoelectroencephalography.

RESULTS

Patients with depression in conditions of physiological rest have a statistically significantly higher tone of resistive vessels and medium-caliber arteries, as well as a lower level of elastic properties of the main arteries compared to healthy individuals.

CONCLUSION

The shape of the rheoelectroencephalogram of patients with depressive disorders was characterized by smoothing of the dicrotic wave and its displacement to the top, as well as a slight severity of incisure and an increase in the speed of propagation of the rheographic wave.

NLRP3/caspase-1/GSDMD-mediated pyroptosis exerts a crucial role in astrocyte pathological injury in mouse model of depression

Emerging evidence suggests that astrocyte loss is one of the most important pathological features in the hippocampus of patients with major depressive disorder (MDD) and depressive mice. Pyroptosis is a recently discovered form of programmed cell death depending on Caspase-gasdermin D (Casp-GSDMD), which is involved in multiple neuropsychiatric diseases. However, the involvement of pyroptosis in the onset of MDD and glial pathological injury remains obscure. Here, we observed that depressive mice showed astrocytic pyroptosis, which was responsible for astrocyte loss, and selective serotonin reuptake inhibitor (SSRI) treatment could attenuate the pyroptosis induced by the chronic mild stress (CMS) model. Genetic KO of GSDMD, Casp-1, and astrocytic NOD-like receptor protein 3 (NLRP3) inflammasome in mice alleviated depression-like behaviors and inhibited the pyroptosis-associated protein expression. In contrast, overexpression of astrocytic GSDMD-N-terminal domain (GSDMD-N) in the hippocampus could abolish the improvement of behavioral alterations in GSDMD-deficient mice. This work illustrates that targeting the NLRP3/Casp-1/GSDMD-mediated pyroptosis may provide potential therapeutic benefits to stress-related astrocyte loss in the pathogenesis of depression.

Metals associated neurodegeneration in Parkinson's disease: Insight to physiological, pathological mechanisms and management

Parkinson's disease (PD) is a deliberately progressive neurological disorder, arises due to degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The loss of dopaminergic nerves and dopamine deficiency leads to motor symptoms characterized by rigidity, tremor, and bradykinesia. Heavy metals and trace elements play various physiological and pathological roles in the nervous system. Excessive exposure to toxic metals like mercury (Hg), lead (Pb), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), aluminium (Al), arsenic (As), cadmium(cd), and selenium (Se) cross the blood-brain barrier to enter into the brain and leads to dopaminergic neuronal degeneration. Excessive concentrations of heavy metals in the brain promote oxidative stress, mitochondrial dysfunction, and the formation of α-synuclein leads to dopaminergic neuronal damage. There is increasing evidence that heavy metals normally present in the human body in minute concentration also cause accumulation to initiate the free radical formation and affecting the basal ganglia signaling. In this review, we explored how these metals affect brain physiology and their roles in the accumulation of toxic proteins (α-synuclein and Lewy bodies). We have also discussed the metals associated with neurotoxic effects and their prevention as management of PD. Our goal is to increase the awareness of metals as players in the onset and progression of PD.

Brain Neurotransmitter Modulation by Gut Microbiota in Anxiety and Depression

Anxiety and depression are highly prevalent mental illnesses worldwide and have long been thought to be closely associated to neurotransmitter modulation. There is growing evidence indicating that changes in the composition of the gut microbiota are related to mental health including anxiety and depression. In this review, we focus on combining the intestinal microbiota with serotonergic, dopaminergic, and noradrenergic neurotransmission in brain, with special emphasis on the anxiety- and depression-like behaviors in stress-related rodent models. Therefore, we reviewed studies conducted on germ-free rodents, or in animals subjected to microbiota absence using antibiotics, as well as via the usage of probiotics. All the results strongly support that the brain neurotransmitter modulation by gut microbiota is indispensable to the physiopathology of anxiety and depression. However, a lot of work is needed to determine how gut microbiota mediated neurotransmission in human brain has any physiological significance and, if any, how it can be used in therapy. Overall, the gut microbiota provides a novel way to alter neurotransmitter modulation in the brain and treat gut–brain axis diseases, such as anxiety and depression.

Xiaoyao Pills Attenuate Inflammation and Nerve Injury Induced by Lipopolysaccharide in Hippocampal Neurons In Vitro

Lipopolysaccharides (LPS) are proinflammation mediators that can induce the inflammatory model of the hippocampal neuron, and neuroinflammation participates in the pathophysiology of depression. Xiaoyao Pill is a classical Chinese medicine formula that has been used for the treatment of mental disorders such as depression in China since the Song dynasty. We established a hippocampal neuronal cell inflammation model by LPS and investigate the intervention effect and mechanism of Xiaoyao Pills. The expression levels of IL-6, TNF-α, IDO, 5-HT, brain-derived neurotrophic factor, and β-nerve growth factor were detected by enzyme-linked immunosorbent assay. mRNA levels of IL-6, TNF-α, 5-HT1A, IDO-1, brain-derived neurotrophic factor, nerve growth factor, tropomyosin receptor kinase B, tropomyosin receptor kinase A, and cAMP response element-binding protein were detected by reverse transcription-polymerase chain reaction. To further validate, protein expression was determined by western blot and immunofluorescence. Lipopolysaccharide-induced neuroinflammatory state resulted in the release of IL-6, TNF-α, and IDO and a decrease of BDNF, NGF, TrkB, TrkA, CREB, p-CREB, p-CREB/CREB, and SYP and inhibited hippocampal neurogenesis in the hippocampal neuron. Xiaoyao Pills significantly decreased the levels of IL-6, TNF-α, and IDO in cell supernatant and increased the expression of BDNF, NGF, TrkB, TrkA, CREB, p-CREB, p-CREB/CREB, and SYP as well as the average optical density of BrdU/NeuN double-labelled positive cells. Our study shows that lipopolysaccharides induce inflammation and nerve damage in hippocampal neurons, which are closely related to the pathological mechanism of depression. Xiaoyao Pills (XYW) play an important neuroprotective effect, which is related to its inhibition of neuronal inflammation and promoting the recovery of nerve injury. These results provide a pharmacologic basis for the treatment of depression of XYW in clinical application.