The Role of BDNF on Neural Plasticity in Depression

Potential anxiolytic and antidepressant-like effects of luteolin in a chronic constriction injury rat model of neuropathic pain: Role of oxidative stress, neurotrophins, and inflammatory factors

This study aimed to examine the effects of luteolin (LUT) on chronic neuropathic pain (NP)-induced mood disorders (i.e., anxiety and depression) by regulating oxidative stress, neurotrophic factors (NFs), and neuroinflammation. Chronic constrictive injury (CCI) was used to induce NP in the animals. Animals in the treatment groups received LUT in three doses of 10, 25, and 50 mg/kg for 21 days. The severity of pain and mood disorders were examined. Finally, animals were sacrificed, and their brain tissue was used for molecular and histopathological studies. CCI led to cold allodynia and thermal hyperalgesia. Mood alterations were proven in the CCI group, according to the behavioral tests. Levels of glial cell-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF), B-cell lymphoma-2 (Bcl2), superoxide dismutase (SOD), catalase (CAT), and nuclear factor erythroid-2-related factor 2 (Nrf2) were reduced in the hippocampus (HPC) and prefrontal cortex (PFC). Furthermore, the levels of MDA, Bcl-2-associated X protein (Bax), and inflammatory markers, including nuclear factor kappa B (NF-κB), NLR family pyrin domain containing 3 (NLRP3), interleukin-1β (IL-1β), IL-18, IL-6, and tumor necrosis factor-α (TNF-α) significantly increased in the HPC and PFC following CCI induction. LUT treatment reversed the behavioral alterations via regulation of oxidative stress, neurotrophines, and inflammatory mediators in the HPC and PFC. Findings confirmed the potency of LUT in the improvement of chronic pain-induced anxiety- and depressive-like symptoms, probably through antioxidant, anti-inflammatory, and neuroprotective properties in the HPC and PFC.

The effects of acupuncture on depression by regulating BDNF-related balance via lateral habenular nucleus BDNF/TrkB/CREB signaling pathway in rats

Depression is a major mental disease worldwide, causing dysfunction of Lateral Habenular (LHb). As a non-invasive alternative, acupuncture (AP) has been widely used to treat depression in clinic, yet few basic studies have been focused on the effects and mechanism of acupuncture on synaptic plasticity in LHb. Therefore, this study aimed to explore the potential mechanism of the antidepressant effect of acupuncture. Male Sprague-Dawley (SD) rats were randomly divided into control, chronic unpredictable mild stress (CUMS), AP, fluoxetine (FLX), acupoint catgut embedding (ACE), sham-ACE groups (n = 9/group). Rats were given a 28-day treatment at the Shangxing (GV23) and Fengfu (GV16) acupoints with acupuncture, ACE, sham-ACE or fluoxetine (2.1 mg/kg). The results showed that AP, FLX and ACE suppressed the behavioral deficits, increased the level of the 5-hydroxytryptamine and FNDC5/IRISIN in serum, also reduced the expression of pro-BDNF impacted by CUMS. Both AP and FLX ameliorated the %area of IBA-1, GFAP, BrdU and DCX in the LHb and increased the expression of BDNF/TrkB/CREB, with non-significant difference between the two groups These findings suggest that AP therapy relieves depression-related manifestations in depressed rats, suggesting a potential mechanism via the BDNF/TrkB/CREB pathway in LHb.

BDNF Unveiled: Exploring Its Role in Major Depression Disorder Serotonergic Imbalance and Associated Stress Conditions

Brain-derived neurotrophic factor (BDNF) is a neurotrophin that plays a significant role in the survival and development of neurons, being involved in several diseases such as Alzheimer's disease and major depression disorder. The association between BDNF and major depressive disorder is the subject of extensive research. Indeed, numerous studies indicate that decreased levels of BDNF are linked to an increased occurrence of depressive symptoms, neuronal loss, and cortical atrophy. Moreover, it has been observed that antidepressive therapy can help restore BDNF levels. In this review, we will focus on the role of BDNF in major depression disorder serotonergic imbalance and associated stress conditions, particularly hypothalamic-pituitary-adrenal (HPA) axis dysregulation and oxidative stress. All of these features are highly connected to BDNF signaling pathways in the context of this disease, and exploring this topic will aim to advance our understanding of the disorder, improve diagnostic and treatment approaches, and potentially identify new therapeutic targets to alleviate the heavy burden of depression on society.

Bridging the Gap between Basic Research and Clinical Practice: The Growing Role of Translational Neurorehabilitation

Translational neuroscience is intended as a holistic approach in the field of brain disorders, starting from the basic research of cerebral morphology and with the function of implementing it into clinical practice. This concept can be applied to the rehabilitation field to promote promising results that positively influence the patient's quality of life. The last decades have seen great scientific and technological improvements in the field of neurorehabilitation. In this paper, we discuss the main issues related to translational neurorehabilitation, from basic research to current clinical practice, and we also suggest possible future scenarios.

Interventional Mental Health: A Transdisciplinary Approach to Novel Psychiatric Care Delivery

Mental health disorders are among the most common health conditions in the United States. Traditional clinical treatments rely on psychiatric counseling and, in many cases, prescription medications. We propose an innovative model, Interventional Mental Health, which employs a combination of modalities through a multifaceted approach to treat conditions that have exhibited limited responsiveness to traditional methods and individuals afflicted with multiple comorbidities simultaneously. We hypothesize that creating a unique treatment algorithm combining current therapeutic modalities such as Stellate Ganglion Blocks (SGB), Transcranial Magnetic Stimulation (TMS) therapy, and ketamine therapy, within a consolidated timeframe, will yield synergistic outcomes among patients presenting with comorbid post-traumatic stress disorder (PTSD), depression, and/or anxiety.

Understanding the Neuroplastic Effects of Auricular Vagus Nerve Stimulation in Animal Models of Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

Transauricular vagus nerve stimulation (taVNS) is being studied as a feasible intervention for stroke, but the mechanisms by which this non-invasive technique acts in the cortex are still broadly unknown.

OBJECTIVES

This study aimed to systematically review the current pre-clinical evidence in the auricular vagus nerve stimulation (aVNS) neuroplastic effects in stroke.

METHODS

We searched, in December of 2022, in Medline, Cochrane, Embase, and Lilacs databases. The authors executed the extraction of the data on Excel. The risk of bias was evaluated by adapted Cochrane Collaboration's tool for animal studies (SYRCLES's RoB tool).

RESULTS

A total of 8 studies published between 2015 and 2022 were included in this review, including 391 animal models. In general, aVNS demonstrated a reduction in neurological deficits (SMD = -1.97, 95% CI -2.57 to -1.36, I2 = 44%), in time to perform the adhesive removal test (SMD = -2.26, 95% CI -4.45 to -0.08, I2 = 81%), and infarct size (SMD = -1.51, 95% CI -2.42 to -0.60, I2 = 58%). Regarding the neuroplasticity markers, aVNS showed to increase microcapillary density, CD31 proliferation, and BDNF protein levels and RNA expression.

CONCLUSIONS

The studies analyzed show a trend of results that demonstrate a significant effect of the auricular vagal nerve stimulation in stroke animal models. Although the aggregated results show high heterogeneity and high risk of bias. More studies are needed to create solid conclusions.

The impact of antidepressants on human neurodevelopment: Brain organoids as experimental tools

The use of antidepressants during pregnancy benefits the mother's well-being, but the effects of such substances on neurodevelopment remain poorly understood. Moreover, the consequences of early exposure to antidepressants may not be immediately apparent at birth. In utero exposure to selective serotonin reuptake inhibitors (SSRIs) has been related to developmental abnormalities, including a reduced white matter volume. Several reports have observed an increased incidence of autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) after prenatal exposure to SSRIs such as sertraline, the most widely prescribed SSRI. The advent of human-induced pluripotent stem cell (hiPSC) methods and assays now offers appropriate tools to test the consequences of such compounds for neurodevelopment in vitro. In particular, hiPSCs can be used to generate cerebral organoids - self-organized structures that recapitulate the morphology and complex physiology of the developing human brain, overcoming the limitations found in 2D cell culture and experimental animal models for testing drug efficacy and side effects. For example, single-cell RNA sequencing (scRNA-seq) and electrophysiological measurements on organoids can be used to evaluate the impact of antidepressants on the transcriptome and neuronal activity signatures in developing neurons. While the analysis of large-scale transcriptomic data depends on dimensionality reduction methods, electrophysiological recordings rely on temporal data series to discriminate statistical characteristics of neuronal activity, allowing for the rigorous analysis of the effects of antidepressants and other molecules that affect the developing nervous system, especially when applied in combination with relevant human cellular models such as brain organoids.

The pharmacological bases for repurposing statins in depression: a review of mechanistic studies

Statins are commonly prescribed medications widely investigated for their potential actions on the brain and mental health. Pre-clinical and clinical evidence suggests that statins may play a role in the treatment of depressive disorders, but only the latter has been systematically assessed. Thus, the physiopathological mechanisms underlying statins' putative antidepressant or depressogenic effects have not been established. This review aims to gather available evidence from mechanistic studies to strengthen the pharmacological basis for repurposing statins in depression. We used a broad, well-validated search strategy over three major databases (Pubmed/MEDLINE, Embase, PsychINFO) to retrieve any mechanistic study investigating statins' effects on depression. The systematic search yielded 8068 records, which were narrowed down to 77 relevant papers. The selected studies (some dealing with more than one bodily system) described several neuropsychopharmacological (44 studies), endocrine-metabolic (17 studies), cardiovascular (6 studies) and immunological (15 studies) mechanisms potentially contributing to the effects of statins on mood. Numerous articles highlighted the beneficial effect of statins on depression, particularly through positive actions on serotonergic neurotransmission, neurogenesis and neuroplasticity, hypothalamic-pituitary axis regulation and modulation of inflammation. The role of other mechanisms, especially the association between statins, lipid metabolism and worsening of depressive symptoms, appears more controversial. Overall, most mechanistic evidence supports an antidepressant activity for statins, likely mediated by a variety of intertwined processes involving several bodily systems. Further research in this area can benefit from measuring relevant biomarkers to inform the selection of patients most likely to respond to statins' antidepressant effects while also improving our understanding of the physiopathological basis of depression.

Correlation of brain-derived neurotrophic factor with severity of depression and treatment response

Background

Brain-derived neurotrophic factor (BDNF) is a modulator of neuroplasticity in the brain. It plays an important role in the pathophysiology of depression through the stress pathway. The information about correlation of BDNF levels with depression severity and treatment response in Indian population is scarce.

Methods

Consecutive 60 never treated cases with depression reporting to a large tertiary care psychiatry unit and 60 healthy matched controls from 01 January 2016 to 31 December 2016 were enrolled for study. Sociodemographic data were collected. Diagnosis of depression was carried out as per International Classification of Diseases-10th revision (ICD-10) diagnostic criteria for research. The Hamilton Rating Scale for Depression (HRSD) was administered and accordingly scored. Venous blood for BDNF levels was collected from all cases and controls. Cases were reassessed after 04 weeks of treatment with HRSD and BDNF levels.

Results

The mean level of serum BDNF among cases (18.56 ng/ml) was found to be reduced significantly as compared with healthy controls (32.41 ng/ml). The mean serum BDNF level (18.56 ng/ml) in never treated cases was significantly negatively correlated with the median clinical HRSD score (18.5). There was a significant increase in the mean level of serum BDNF after antidepressant treatment.

Conclusion

The study has revealed statistically significant low levels of serum BDNF in cases not exposed to treatment with depression compared with healthy controls. There was significant negative correlation of levels of serum BDNF with depression severity. The levels of serum BDNF significantly increased after four weeks of treatment.

Application of Vagus Nerve Stimulation in Spinal Cord Injury Rehabilitation

Spinal cord injury (SCI) is a prevalent devastating condition causing significant morbidity and mortality, especially in developing countries. The pathophysiology of SCI involves ischemia, neuroinflammation, cell death, and scar formation. Due to the lack of definitive therapy for SCI, interventions mainly focus on rehabilitation to reduce deterioration and improve the patient's quality of life. Currently, rehabilitative exercises and neuromodulation methods such as functional electrical stimulation, epidural electrical stimulation, and transcutaneous electrical nerve stimulation are being tested in patients with SCI. Other spinal stimulation techniques are being developed and tested in animal models. However, often these methods require complex surgical procedures and solely focus on motor function. Vagus nerve stimulation (VNS) is currently used in patients with epilepsy, depression, and migraine and is being investigated for its application in other disorders. In animal models of SCI, VNS significantly improved locomotor function by ameliorating inflammation and improving plasticity, suggesting its use in human subjects. SCI patients also suffer from nonmotor complications, including pain, gastrointestinal dysfunction, cardiovascular disorders, and chronic conditions such as obesity and diabetes. VNS has shown promising results in alleviating these conditions in non-SCI patients, which makes it a possible therapeutic option in SCI patients.

Contribution of the opioid system to depression and to the therapeutic effects of classical antidepressants and ketamine

Major depressive disorder (MDD) afflicts approximately 5 % of the world population, and about 30-50 % of patients who receive classical antidepressant medications do not achieve complete remission (treatment resistant depressive patients). Emerging evidence suggests that targeting opioid receptors mu (MOP), kappa (KOP), delta (DOP), and the nociceptin/orphanin FQ receptor (NOP) may yield effective therapeutics for stress-related psychiatric disorders. As depression and pain exhibit significant overlap in their clinical manifestations and molecular mechanisms involved, it is not a surprise that opioids, historically used to alleviate pain, emerged as promising and effective therapeutic options in the treatment of depression. The opioid signaling is dysregulated in depression and numerous preclinical studies and clinical trials strongly suggest that opioid modulation can serve as either an adjuvant or even an alternative to classical monoaminergic antidepressants. Importantly, some classical antidepressants require the opioid receptor modulation to exert their antidepressant effects. Finally, ketamine, a well-known anesthetic whose extremely efficient antidepressant effects were recently discovered, was shown to mediate its antidepressant effects via the endogenous opioid system. Thus, although opioid system modulation is a promising therapeutical venue in the treatment of depression further research is warranted to fully understand the benefits and weaknesses of such approach.

Cardamom oil ameliorates behavioral and neuropathological disorders in a rat model of depression induced by reserpine

ETHNOPHARMACOLOGICAL RELEVANCE

Depression is a public health problem. Despite the availability of treatment options, its prevalence is increasing. A high rate of treatment failure is often reported, along with considerable side effects associated with synthetic antidepressants. Therefore, developing effective and safe antidepressants from traditional herbs or natural products as an alternative strategy is warranted to avoid side effects and increase drug efficacy. In traditional medicine, cardamom has traditionally been used to treat conditions like asthma, tooth and gum infections, cataracts, nausea, diarrhea, and even depression and anxiety as well as some problems with the heart, kidneys, and digestive system.

AIM OF THE STUDY

The current study aimed to evaluate the antidepressant activity of cardamom oil in a rat model of depression induced by reserpine and compare it with the activity of the antidepressant drug fluoxetine.

MATERIALS AND METHODS

Depression-like symptoms were induced in male rats by daily i. p. injection of reserpine (0.2 mg/kg/d for 15 d followed by 0.1 mg/kg/d for 21 d to maintain the depressive state), and the rats were treated with cardamom oil (oral dose = 200 mg/kg/d) for 21 d along with the maintenance dose of reserpine. We performed behavioral tests (forced swimming test and open-field test) and evaluated biochemical markers of depression.

RESULTS

Our findings revealed that cardamom oil attenuated depression-like symptoms in reserpine-injected rats by improving the behavioral changes measured by the forced swimming test and the locomotor activities measured by the open-field test. In reserpine-injected rats, cardamom oil exerted antidepressant-like effects by modulating lower levels of brain monoamine neurotransmitters (serotonin, norepinephrine, and dopamine), GSH, and higher oxido-nitrosative stress parameters (malondialdehyde and nitric oxide). Moreover, cardamom oil alleviated depression-like behaviors by lowering monoamine oxidase activity and raising the activities of Na⁺/K⁺-ATPase and acetylcholinesterase and levels of a brain-derived neurotrophic factor in the cortex and hippocampus.

CONCLUSION

We recommend the use of cardamom oil as a safe and reliable treatment or an adjuvant for preventing depression-like symptoms in patients suffering from depression.

Long-term consequences of COVID-19 on mental health and the impact of a physically active lifestyle: a narrative review

BACKGROUND

Coronavirus-19 disease (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Respiratory viruses damage not only the upper respiratory tract in humans, but also several different organs such as the brain. Some of the neurological consequences of COVID-19 reported are anosmia, headache, stroke, declined cognitive function, and impaired mental health, among others. People who had COVID-19 have a higher risk of sequelae in the central nervous system (CNS). However, it is not known which are all possible sequelae and how long will last the long-term effects of the COVID-19 pandemic on behavioral patterns and quality of life.

AIM

We intend to address the long-term impacts of COVID-19 on mental health and the relevance of physical exercise during the pandemic.

METHODS

We conducted a literature search using PubMed to find the articles that were related to these themes.

RESULTS

We found 23,489 papers initially, and then we applied the inclusion/exclusion criteria to narrow down our search to 3617 articles and selected 1380 eligible articles after a thorough reading of titles and abstracts. The findings indicated that COVID-19 impacted general mental health and led many not only hospitalized patients to develop cognitive decline, memory impairment, anxiety, sleep alterations, and depressive-like behavior. Furthermore, the fear of vaccines and their effects had negatively affected mental health and directly impacted mortality rates in unvaccinated COVID-19 patients.

CONCLUSIONS

Preventive measures must be undertaken, such as the vaccination of the entire population, vaccination hesitancy discouragement by creating awareness among individuals, and people's engagement in a physically active lifestyle, since being physically active is a low-cost and effective measure to restore or inhibit the negative outcomes from COVID-19 on mental health.

Mesenchymal stromal cell-derived secretome-based therapy for neurodegenerative diseases: overview of clinical trials

BACKGROUND

Over the past few years, mesenchymal stromal cells (MSCs) have attracted a great deal of scientific attention owing to their promising results in the treatment of incurable diseases. However, there are several concerns about their possible side effects after direct cell transplantation, including host immune response, time-consuming cell culture procedures, and the dependence of cell quality on the donor, which limit the application of MSCs in clinical trials. On the other hand, it is well accepted that the beneficial effects of MSCs are mediated by secretome rather than cell replacement. MSC secretome refers to a variety of bioactive molecules involved in different biological processes, specifically neuro-regeneration.

MAIN BODY

Due to the limited ability of the central nervous system to compensate for neuronal loss and relieve disease progress, mesenchymal stem cell products may be used as a potential cure for central nervous system disorders. In the present study, the therapeutic effects of MSC secretome were reviewed and discussed the possible mechanisms in the three most prevalent central nervous system disorders, namely Alzheimer's disease, multiple sclerosis, and Parkinson's disease. The current work aimed to help discover new medicine for the mentioned complications.

CONCLUSION

The use of MSC-derived secretomes in the treatment of the mentioned diseases has encouraging results, so it can be considered as a treatment option for which no treatment has been introduced so far.

Clinical Improvement in Depression and Cognitive Deficit Following Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is a long-standing treatment choice for disorders such as depression when pharmacological treatments have failed. However, a major drawback of ECT is its cognitive side effects. While numerous studies have investigated the therapeutic effects of ECT and its mechanism, much less research has been conducted regarding the mechanism behind the cognitive side effects of ECT. As both clinical remission and cognitive deficits occur after ECT, it is possible that both may share a common mechanism. This review highlights studies related to ECT as well as those investigating the mechanism of its outcomes. The process underlying these effects may lie within BDNF and NMDA signaling. Edema in the astrocytes may also be responsible for the adverse cognitive effects and is mediated by metabotropic glutamate receptor 5 and the protein Homer1a.

Ketamine affects homeostatic sleep regulation in the absence of the circadian sleep-regulating component in freely moving rats

Pharmacological effects of ketamine may affect homeostatic sleep regulation via slow wave related mechanisms. In the present study effects of ketamine applied at anesthetic dose (80 mg/kg) were tested on neocortical electric activity for 24 h in freely moving rats. Ketamine effects were compared to changes during control (saline) injections and after 6 h gentle handling sleep deprivation (SD). As circadian factors may mask drug effects, an illumination protocol consisting of short light-dark cycles was applied. Ketamine application induced a short hypnotic stage with characteristic slow cortical rhythm followed by a long-lasting hyperactive waking resulting pharmacological SD. Coherence analysis indicated an increased level of local synchronization in broad local field potential frequency ranges during hyperactive waking but not during natural- or SD-evoked waking. Both slow wave sleep and rapid eye movement sleep were replaced after the termination of the ketamine effect. Our results show that both ketamine-induced hypnotic state and hyperactive waking can induce homeostatic sleep pressure with comparable intensity as 6 h SD, but ketamine-induced waking was different compared to the SD-evoked one. Both types of waking stages were different compared to spontaneous waking but all three types of wakefulness can engage the homeostatic sleep regulating machinery to generate sleep pressure dissipated by subsequent sleep. Current-source density analysis of the slow waves showed that cortical transmembrane currents were stronger during ketamine-induced hypnotic stage compared to both sleep replacement after SD and ketamine application, but intracortical activation patterns showed only quantitative differences. These findings may hold some translational value for human medical ketamine applications aiming the treatment of depression-associated sleep problems, which can be alleviated by the homeostatic sleep effect of the drug without the need for an intact circadian regulation.

Phosphodiesterase inhibitors in psychiatric disorders

RATIONALE

Challenges in drug development for psychiatric disorders have left much room for the introduction of novel treatments with better therapeutic efficacies and indices. As a result, intense research has focused on identifying new targets for developing such pharmacotherapies. One of these targets may be the phosphodiesterase (PDE) class of enzymes, which play important roles in intracellular signaling. Due to their critical roles in cellular pathways, these enzymes affect diverse neurobiological functions from learning and memory formation to neuroinflammation.

OBJECTIVES

In this paper, we reviewed studies on the use of PDE inhibitors (PDEIs) in preclinical models and clinical trials of psychiatric disorders including depression, anxiety, schizophrenia, post-traumatic stress disorder (PTSD), bipolar disorder (BP), sexual dysfunction, and feeding disorders.

RESULTS

PDEIs are able to improve symptoms of psychiatric disorders in preclinical models through activating the cAMP-PKA-CREB and cGMP-PKG pathways, attenuating neuroinflammation and oxidative stress, and stimulating neural plasticity. The most promising therapeutic candidates to emerge from these preclinical studies are PDE2 and PDE4 inhibitors for depression and anxiety and PDE1 and PDE10 inhibitors for schizophrenia. Furthermore, PDE3 and 4 inhibitors have shown promising results in clinical trials in patients with depression and schizophrenia.

CONCLUSIONS

Larger and better designed clinical studies of PDEIs in schizophrenia, depression, and anxiety are warranted to facilitate their translation into the clinic. Regarding the other conditions discussed in this review (most notably PTSD and BP), better characterization of the effects of PDEIs in preclinical models is required before clinical studies.

Perceived changes in the mental well-being among Nigerians due to Ramadan Intermittent Fasting during the COVID-19 pandemic

INTRODUCTION

Muslims fast every year during the month of Ramadan from dawn until dusk. This study examined mental well-being and correlating factors among Nigerian adults who observed Ramadan intermittent fasting (RIF).

METHODS

A validated generalized anxiety disorder-2 and Patient Health Questionnaire-2, the four-item spiritual well-being index, and the Islamic intrinsic religiosity questionnaire were used to collect data about mental well-being (depression, anxiety), spirituality, and intrinsic religiosity through a web-based survey between the May 9, 2021 (27th of Ramadan, 1442) and the June 4, 2021 (29th of Shawwal, 1442). We studied the mental well-being of respondents over a period of 4 weeks before Ramadan (BR) and during the 4 weeks of Ramadan between the April 12, 2021 and the May 12, 2021(DR). Multinomial regression analysis was used to determine the factors associated with depression and anxiety. This research did not receive any grant or funding.

RESULTS

A total of 770 adult Nigerians who observed RIF study were included in this cross-sectional study. When compared to mental well-being BR, observing RIF by Nigerian adult respondents was associated with a significant improvement in their mental well-being. A higher proportion of respondents felt less depressed DR (61.3% vs. 56.5%. < .001). Interest and pleasure in doing things improved DR than BR (p= 0.007) and respondents felt less nervous and anxious (60.7% vs. 57.1%, respectively; p <.001). Mental well-being was independently associated with sociodemographic characteristics, physical activity, and perceived relationships.

CONCLUSIONS

This study found significant improvement in mental well-being DR compared to BR despite the ongoing COVID-19 pandemic. The effect of RIF on mental well-being needs further research with multicentric studies among different sets of ethnic populations.

The Role of BDNF as a Biomarker in Cognitive and Sensory Neurodegeneration

Brain-derived neurotrophic factor (BDNF) has a crucial function in the central nervous system and in sensory structures including olfactory and auditory systems. Many studies have highlighted the protective effects of BDNF in the brain, showing how it can promote neuronal growth and survival and modulate synaptic plasticity. On the other hand, conflicting data about BDNF expression and functions in the cochlear and in olfactory structures have been reported. Several clinical and experimental research studies showed alterations in BDNF levels in neurodegenerative diseases affecting the central and peripheral nervous system, suggesting that BDNF can be a promising biomarker in most neurodegenerative conditions, including Alzheimer's disease, shearing loss, or olfactory impairment. Here, we summarize current research concerning BDNF functions in brain and in sensory domains (olfaction and hearing), focusing on the effects of the BDNF/TrkB signalling pathway activation in both physiological and pathological conditions. Finally, we review significant studies highlighting the possibility to target BDNF as a biomarker in early diagnosis of sensory and cognitive neurodegeneration, opening new opportunities to develop effective therapeutic strategies aimed to counteract neurodegeneration.

The roles of neuroinflammation and glutamatergic excitotoxicity in treatment-resistant depression

ABSTRACT

Major depressive disorder affects nearly 20% of people during their lifetime. A growing body of evidence supports the theory that neuroinflammation plays a prominent role in the neurobiology of depression, which implicates glutamate and gamma aminobutyric acid as key factors in the pathophysiology of the disease process. This article reviews the pathologic pathways of glutamate excess in the central nervous system and how they may be implicated in the underlying disorder of treatment-resistant depression and targeted for treatment.

Serotonin is a Common Thread Linking Different Classes of Antidepressants

Depression pathology remains elusive. The monoamine hypothesis has placed much focus on serotonin, but due to the variable clinical efficacy of monoamine reuptake inhibitors, the community is looking for alternative therapies such as ketamine (synaptic plasticity and neurogenesis theory of antidepressant action). There is evidence that different classes of antidepressants may affect serotonin levels; a notion we test here. We measure hippocampal serotonin in mice with voltammetry and study the effects of acute challenges of antidepressants. We find that pseudo-equivalent doses of these drugs similarly raise ambient serotonin levels, despite their differing pharmacodynamics because of differences in Uptake 1 and 2, rapid SERT trafficking and modulation of serotonin by histamine. These antidepressants have different pharmacodynamics but have strikingly similar effects on extracellular serotonin. Our findings suggest that serotonin is a common thread that links clinically effective antidepressants, synergizing different theories of depression (synaptic plasticity, neurogenesis and the monoamine hypothesis).

Effect of prenatal stress and extremely low-frequency electromagnetic fields on anxiety-like behavior in female rats: With an emphasis on prefrontal cortex and hippocampus

OBJECTIVE

Prenatal stress (PS) is a problematic situation resulting in psychological implications such as social anxiety. Ubiquitous extremely low-frequency electromagnetic fields (ELF-EMF) have been confirmed as a potential physiological stressor; however, useful neuroregenerative effect of these types of electromagnetic fields has also frequently been reported. The aim of the present study was to survey the interaction of PS and ELF-EMF on anxiety-like behavior.

METHOD

A total of 24 female rats 40 days of age were distributed into four groups of 6 rats each: control, stress (their mothers were exposed to stress), EMF (their mothers underwent to ELF-EMF), and EMF/stress (their mothers concurrently underwent to stress and ELF-EMF). The rats were assayed using elevated plus-maze and open field tests.

RESULTS

Expressions of the hippocampus GAP-43, BDNF, and caspase-3 (cas-3) were detected by immunohistochemistry in Cornu Ammonis 1 (CA1) and dentate gyrus (DG) of the hippocampus and prefrontal cortex (PFC). Anxiety-like behavior increased in all treatment groups. Rats in the EMF/stress group presented more serious anxiety-like behavior. In all treatment groups, upregulated expression of cas-3 was seen in PFC, DG, and CA1 and downregulated expression of BDNF and GAP-43 was seen in PFC and DG and the CA1. Histomorphological study showed vast neurodegenerative changes in the hippocampus and PFC.

CONCLUSION

The results showed ,female rats that underwent PS or/and EMF exhibited critical anxiety-like behavior and this process may be attributed to neurodegeneration in PFC and DG of the hippocampus and possibly decreased synaptic plasticity so-called areas.

Synergistic effects of lipopolysaccharide and rotenone on dopamine neuronal damage in rats

INTRODUCTION

The etiology of Parkinson's disease (PD) is still unknown. Until now, oxidative stress and neuroinflammation play a crucial role in the pathogenesis of PD. However, the specific synergistic role of oxidative stress and neuroinflammation in the occurrence and development of PD remains unclear.

METHODS

The changes in motor behavior, dopamine (DA) neurons quantification and their mitochondrial respiratory chain, glial cells activation and secreted cytokines, Nrf2 signaling pathway, and redox balance in the brain of rats were evaluated.

RESULTS

Lipopolysaccharide (LPS)-induced neuroinflammation and rotenone (ROT)-induced oxidative stress synergistically aggravated motor dysfunction, DA neuron damage, activation of glial cells, and release of related mediators, activation of Nrf2 signaling and destruction of oxidative balance. In addition, further studies indicated that after ROT-induced oxidative stress caused direct damage to DA neurons, LPS-induced inflammatory effects had stronger promoting neurotoxic effects on the above aspects.

CONCLUSIONS

Neuroinflammation and oxidative stress synergistically aggravated DA neuronal loss. Furtherly, oxidative stress followed by neuroinflammation caused more DA neuronal loss than neuroinflammation followed by oxidative stress.

A Microbial-Based Approach to Mental Health: The Potential of Probiotics in the Treatment of Depression

Probiotics are currently the subject of intensive research pursuits and also represent a multi-billion-dollar global industry given their vast potential to improve human health. In addition, mental health represents a key domain of healthcare, which currently has limited, adverse-effect prone treatment options, and probiotics may hold the potential to be a novel, customizable treatment for depression. Clinical depression is a common, potentially debilitating condition that may be amenable to a precision psychiatry-based approach utilizing probiotics. Although our understanding has not yet reached a sufficient level, this could be a therapeutic approach that can be tailored for specific individuals with their own unique set of characteristics and health issues. Scientifically, the use of probiotics as a treatment for depression has a valid basis rooted in the microbiota-gut-brain axis (MGBA) mechanisms, which play a role in the pathophysiology of depression. In theory, probiotics appear to be ideal as adjunct therapeutics for major depressive disorder (MDD) and as stand-alone therapeutics for mild MDD and may potentially revolutionize the treatment of depressive disorders. Although there is a wide range of probiotics and an almost limitless range of therapeutic combinations, this review aims to narrow the focus to the most widely commercialized and studied strains, namely Lactobacillus and Bifidobacterium, and to bring together the arguments for their usage in patients with major depressive disorder (MDD). Clinicians, scientists, and industrialists are critical stakeholders in exploring this groundbreaking concept.

Mal de Debarquement Syndrome explained by a vestibulo-cerebellar oscillator

Mal de Debarquement Syndrome (MdDS) is a puzzling central vestibular disorder characterized by a long-lasting perception of oscillatory postural instability that may occur after sea travels or flights. We have postulated that MdDS originates from the post-disembarking persistence of an adaptive internal oscillator consisting of a loop system, involving the right and left vestibular nuclei, and the Purkinje cells of the right and left flocculonodular cerebellar cortex, connected by GABAergic and glutamatergic fibers. We have formulated here a mathematical model of the vestibulo-cerebellar loop system and carried out a computational analysis based on a set of differential equations describing the interactions among the loop elements and containing Hill functions that model input-output firing rates relationships among neurons. The analysis indicates that the system acquires a spontaneous and permanent oscillatory behavior for a decrease of threshold and an increase of sensitivity in neuronal input-output responses. These results suggest a role for synaptic plasticity in MdDS pathophysiology, thus reinforcing our previous hypothesis that MdDS may be the result of excessive synaptic plasticity acting on the vestibulo-cerebellar network during its entraining to an oscillatory environment. Hence, our study points to neuroendocrine pathways that lead to increased synaptic response as possible new therapeutic targets for the clinical treatment of the disorder.

Dulaglutide impedes depressive-like behavior persuaded by chronic social defeat stress model in male C57BL/6 mice: Implications on GLP-1R and cAMP/PKA signaling pathway in the hippocampus

AIM

There is a well-founded relation between bullying and depression, which may eventually lead to suicidal behavior. Repurposing of antidiabetic drugs for the treatment of depression started to glow, which open new horizons to introduce the antidiabetic medications as new treatment picks in depression. Dulaglutide has been approved as remedy of type 2 diabetes mellitus (T2DM). Consequently, our scope of work is to investigate the ability of dulaglutide to indulgence depression via deeply reconnoitering the Glucagon-like peptide-1 receptor and cAMP/PKA Signaling Pathway.

MATERIALS AND METHODS

Eighty mice were divided into two groups; one with and the other without the induction of chronic social defeat stress (CSDS). Each group was subdivided into two subsets; the first one was treated with saline for 42 days, while the other was treated with saline for 20 days, then with dulaglutide (0.6 mg/kg/week) for four weeks.

KEY FINDINGS

CSDS group showed a lessening in the social interaction ratio and sucrose consumption. They spent less exploration time in the open arms, and more time in the closed arms in elevated plus maze test as compared to controls. Furthermore, the CSDS group had a higher expression of NOD- like receptor protein-3 which explained the elevation in inflammatory biomarkers (IL-1β, IL-18, IL-6 and TNF-α) along with diminution in GLP-1R, cAMP/PKA levels. Treatment with dulaglutide markedly reversed the above-mentioned parameters via bolstering the GLP-1R/cAMP/PKA pathway.

SIGNIFICANCE

NLRP3 inflammasome activation expedites depression. Dulaglutide activates the GLP-1R/cAMP/PKA pathway, hence offering a novel therapeutic intervention to hinder depression.

Tobacco use modify exon IV BDNF gene methylation levels in depression

This study aimed to investigate BDNF gene methylation in individuals with depression based on tobacco use. Therefore, 384 adults from southeastern Brazil were recruited to assess depression, socioeconomic status, lifestyle, and methylation by pyrosequencing exon IV promoter region of the BDNF gene. The Generalized Linear Model (GzLM) was used to check the effect of depression, tobacco, and the interaction between depression and tobacco use in methylation levels. In addition, the Kruskal-Wallis test, followed by Dunn's post hoc test, was used to compare methylation levels. Interaction between depression and tobacco use was significant at levels of BDNF methylation in the CpG 5 (p = 0.045), 8 (p = 0.016), 9 (p = 0.042), 10 (p = 0.026) and mean 5-11 (p < 0.001). Dunn's post hoc test showed that individuals with depression and tobacco use compared to those with or without depression who did not use tobacco had lower levels of BDNF methylation in CpG 5, 6, 7, 8, 9, 11, and mean 5-11. Therefore, we suggest that tobacco use appears to interfere with BDNF gene methylation in depressed individuals.

Early life adversity across different cell- types in the brain

Early life adversity (ELA)- which includes physical, psychological, emotional, and sexual abuse is one of the most common predictors to diverse psychopathologies later in adulthood. As ELA has a lasting impact on the brain at a developmental stage, recent findings from the field highlighted the specific contributions of different cell types to ELA and their association with long lasting consequences. In this review we will gather recent findings describing morphological, transcriptional and epigenetic alterations within neurons, glia and perineuronal nets and their associated cellular subpopulation. The findings reviewed and summarized here highlight important mechanisms underlying ELA and point to therapeutic approaches for ELA and related psychopathologies later in life.

Oxidative Stress in Depression: The Link with the Stress Response, Neuroinflammation, Serotonin, Neurogenesis and Synaptic Plasticity

Depression is a prevalent, complex, and highly debilitating disease. The full comprehension of this disease is still a global challenge. Indeed, relapse, recurrency, and therapeutic resistance are serious challenges in the fight against depression. Nevertheless, abnormal functioning of the stress response, inflammatory processes, neurotransmission, neurogenesis, and synaptic plasticity are known to underlie the pathophysiology of this mental disorder. The role of oxidative stress in disease and, particularly, in depression is widely recognized, being important for both its onset and development. Indeed, excessive generation of reactive oxygen species and lack of efficient antioxidant response trigger processes such as inflammation, neurodegeneration, and neuronal death. Keeping in mind the importance of a detailed study about cellular and molecular mechanisms that are present in depression, this review focuses on the link between oxidative stress and the stress response, neuroinflammation, serotonergic pathways, neurogenesis, and synaptic plasticity's imbalances present in depression. The study of these mechanisms is important to lead to a new era of treatment and knowledge about this highly complex disease.

Advances in applications of head mounted devices (HMDs): Physical techniques for drug delivery and neuromodulation

Head-mounted medical devices (HMDs) are disruptive inventions representing laboratories and clinical institutions worldwide are climbing the apexes of brain science. These complex devices are inextricably linked with a wide range knowledge containing the Physics, Imaging, Biomedical engineering, Biology and Pharmacology, particularly could be specifically designed for individuals, and finally exerting integrated bio-effect. The salient characteristics of them are non-invasive intervening in human brain's physiological structures, and alterating the biological process, such as thermal ablating the tumor, opening the BBB to deliver drugs and neuromodulating to enhance cognitive performance or manipulate prosthetic. The increasing demand and universally accepted of them have set off a dramatic upsurge in HMDs' studies, seminal applications of them span from clinical use to psychiatric disorders and neurological modulation. With subsequent pre-clinical studies and human trials emerging, the mechanisms of transcranial stimulation methods of them were widely studied, and could be basically came down to three notable approach: magnetic, electrical and ultrasonic stimulation. This review provides a comprehensive overviews of their stimulating mechanisms, and recent advances in clinic and military. We described the potential impact of HMDs on brain science, and current challenges to extensively adopt them as promising alternative treating tools.

Brain-derived neurotrophic factor (BDNF) in perinatal depression: Side show or pivotal factor?

Perinatal depression is the most common psychiatric complication of pregnancy, with its detrimental effects on maternal and infant health widely underrated. There is a pressing need for specific molecular biomarkers, with pregnancy-related decline in brain-derived neurotrophic factor (BDNF) in the blood and downregulation of TrkB receptor in the brain reported in clinical and preclinical studies. In this review, we explore the emerging role of BDNF in reproductive biology and discuss evidence suggesting its deficiency as a risk factor for perinatal depression. With the increasing evidence for restoration of serum BDNF levels by antidepressant therapy, the strengthening association of perinatal depression with deficiency of BDNF supports its potential as a surrogate endpoint for preclinical and clinical studies.

Peripheral brain-derived neurotrophic factor (BDNF) in insomnia: A systematic review and meta-analysis

The brain-derived neurotrophic factor (BDNF) is associated with emotional and cognitive functioning, and it is considered a transdiagnostic biomarker for mental disorders. Literature on insomnia related BDNF changes yielded contrasting results and it has never been synthetized using meta-analysis. To fill this gap, we conducted a systematic review and meta-analysis of case-control studies examining the levels of peripheric BDNF in individuals with insomnia and healthy controls using the PRISMA guidelines. PubMed, Scopus, Medline, PsycINFO and CINAHL were searched up to Nov 2022. Nine studies met the inclusion criteria and were assessed using the Newcastle-Ottawa Scale. Eight studies reported sufficient data for meta-analysis. Random-effects models showed lower BDNF in subjects with insomnia (n = 446) than in controls (n = 706) (Hedge's g = -0.86, 95% CI: -1.39 to -0.32, p = .002). Leave-one-out sensitivity analysis confirmed that the pooled effect size was robust and not driven by any single study. However, given the small sample size, the cross-sectional nature of the measurement, and the high heterogeneity of included data, the results should be cautiously interpreted. Progress in the study of BDNF in insomnia is clinically relevant to better understand the mechanisms that may explain the relationship between disturbed sleep and mental disorders.

Differentially regulated targets in the fast-acting antidepressant effect of (R)-ketamine: A systems biology approach

Approximately two-thirds of patients with major depressive disorder (MDD) fail to respond to conventional antidepressants, suggesting that additional mechanisms are involved in the MDD pathophysiology. In this scenario, the glutamatergic system represents a promising therapeutic target for treatment-resistant depression. To our knowledge, this is the first study using semantic approach with systems biology to identify potential targets involved in the fast-acting antidepressant effects of ketamine and its enantiomers as well as identifying specific targets of (R)-ketamine. We performed a systematic review, followed by a semantic analysis and functional gene enrichment to identify the main biological processes involved in the therapeutic effects of these agents. Protein-protein interaction networks were constructed, and the genes exclusively regulated by (R)-ketamine were explored. We found that the regulation of α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic Acid (AMPA) receptor and N-methyl-d-aspartate (NMDA) receptor subunits-Postsynaptic Protein 95 (PSD-95), Brain Derived Neurotrophic Factor (BDNF), and Tyrosine Receptor Kinase B (TrkB) are shared by the three-antidepressant agents, reinforcing the central role of the glutamatergic system and neurogenesis on its therapeutic effects. Differential regulation of Transforming Growth Factor Beta 1 (TGF-β1) receptors-Mitogen-Activated Protein Kinases (MAPK's), Receptor Activator of Nuclear Factor-Kappa Beta Ligand (RANKL), and Serotonin Transporter (SERT) seems to be particularly involved in (R)-ketamine antidepressant effects. Our data helps further studies investigating the relationship between these targets and the mechanisms of (R)-ketamine and searching for other therapeutic compounds that share the regulation of these specific biomolecules. Ultimately, this study could contribute to improve the fast management of depressive-like symptoms with less detrimental side effects than ketamine and (S)-ketamine.

Impact of genetic deletion of MrgD or Mas receptors in depressive-like behaviour in mice

OBJECTIVES

To evaluate the impact of genetic deletion of receptors of the counterregulatory arms of the renin-angiotensin system in depressive-like behaviours.

METHODS

8-12 weeks-old male mice wild type (WT, C57BL/6J) and mice with genetic deletion of MrgD (MrgD KO) or Mas receptors (Mas KO) were subjected to the Forced Swim Test (FST) and the Tail Suspension Test (TST). Brain-derived neurotrophic factor (BDNF) levels were measured by enzyme-linked immunosorbent assay (ELISA). Blockade of Mas was performed by acute intracerebroventricular (icv) injection of its selective antagonist, A779.

RESULTS

No statistical difference in immobility time was observed between MrgD KO and WT male animals subjected to FST and TST. However, acute icv injection of A779 significantly increased the immobility time of MrgD KO male mice subjected to FST and TST, suggesting the involvement of Mas in preventing depressive-like behaviour. Indeed, Mas KO male animals showed increased immobility time in FST and TST, evidencing a depressive-like behaviour in these animals, in addition to a reduction in BDNF levels in the prefrontal cortex and hippocampus. No changes in BDNF levels were observed in MrgD KO male animals.

CONCLUSION

Our data showed that Mas plays an important role in the neurobiology of depression probably by modulating BDNF expression. On the contrary, lack of MrgD did not alter depressive-like behaviour, which was supported by the lack of alterations in BDNF levels.

The Role of Brain-Derived Neurotrophic Factor (BDNF) in Diagnosis and Treatment of Epilepsy, Depression, Schizophrenia, Anorexia Nervosa and Alzheimer's Disease as Highly Drug-Resistant Diseases: A Narrative Review

Brain-derived neurotrophic factor (BDNF) belongs to the family of neurotrophins, which are growth factors with trophic effects on neurons. BDNF is the most widely distributed neurotrophin in the central nervous system (CNS) and is highly expressed in the prefrontal cortex (PFC) and hippocampus. Its distribution outside the CNS has also been demonstrated, but most studies have focused on its effects in neuropsychiatric disorders. Despite the advances in medicine in recent decades, neurological and psychiatric diseases are still characterized by high drug resistance. This review focuses on the use of BDNF in the developmental assessment, treatment monitoring, and pharmacotherapy of selected diseases, with a particular emphasis on epilepsy, depression, anorexia, obesity, schizophrenia, and Alzheimer's disease. The limitations of using a molecule with such a wide distribution range and inconsistent method of determination are also highlighted.

Brain-derived neurotrophic factor G196A (rs6265) gene polymorphism increases Turner syndrome susceptibility

Brain-derived neurotrophic factor (BDNF) is a member of the nerve growth factor family. It plays a significant role in the regulation of brain metabolic activity, modification of synaptic efficacy, and enhances neuronal survival. A common naturally occurring allelic variation, i.e. G196A (Val66 Met, rs6265) of the BDNF gene is implicated in neuroplasticity. This study analyzes its expression levels and determines the frequency of BDNF G196A gene polymorphism in women with Turner syndrome (TS) compared to the controls. This case-control study comprised 14 TS patients and 8 healthy individuals. The expression levels of BDNF gene in TS patients were checked by qPCR. For BDNF gene, a dynamic expression range along with the presence of G196A polymorphism was found across all TS patients. The effects of Val66 Met mutation on BDNF protein structure and function were studied by molecular dynamics simulations of wild and mutant (Val66 Met) forms. The analysis of different trajectories generated by simulation showed that there was a significant change in the protein structure due to Val66 Met polymorphism, which might lead to functional impairment. This is first time we are reporting the association of BDNF G196A gene polymorphism with TS risk. Our study suggests that in turner patients, BDNF G196A polymorphism may be an important genetic factor predisposing to neuroplasticity risk and can be exploited as diagnostic/prognostic marker for TS. Further study on a large number of TS samples will prove this point beyond doubts or otherwise enriching the much desired repertoire of personalized medicine.

Biomarkers in Child and Adolescent Depression

Despite the significant prevalence of Major Depressive Disorder in the pediatric population, the pathophysiology of this condition remains unclear, and the treatment outcomes poor. Investigating tools that might aid in diagnosing and treating early-onset depression seems essential in improving the prognosis of the future disease course. Recent studies have focused on searching for biomarkers that constitute biochemical indicators of MDD susceptibility, diagnosis, or treatment outcome. In comparison to increasing evidence of possible biomarkers in adult depression, the studies investigating this subject in the youth population are lacking. This narrative review aims to summarize research on molecular and biochemical biomarkers in child and adolescent depression in order to advocate future directions in the research on this subject. More studies on depression involving the youth population seem vital to comprehend the natural course of the disease and identify features that may underlie commonly observed differences in treatment outcomes between adults and children.

Possible role of the NLRP3 inflammasome and the gut-brain axis in multiple sclerosis-related depression

Multiple sclerosis (MS) is an autoimmune and demyelinating disease of the central nervous system that results from complex interactions between genetic and environmental determinants. Patients with MS exhibit a high risk of depression, however, the exact pathomechanisms remain largely unknown. It is becoming widely accepted that the gut-brain axis (GBA) disorders may exert an influence on neuroinflammation and psychiatric symptoms, including so-called MS-related depression. The element suggested as a bridge between intestinal disorders, depression, and MS is an inflammatory response with the central role of the NLR family pyrin domain containing 3 (NLRP3) inflammasome. The pro-inflammatory activity of effector cytokines of the NLRP3 inflammasome forms the hypothesis that it is actively involved in the development of inflammatory and autoimmune diseases. Despite extensive reviews considering the possible origins of MS-related depression, its complex pathophysiology prevents any easy determination of its underlying mechanisms. This paper aims to discuss molecular mechanisms related to the GBA axis that can mediate dysbiosis, intestinal barrier dysfunction, disruption of blood-brain barrier integrity, neuroinflammation, and subsequent manifestation of MS-related major depressive disorder.

18β-Glycyrrhetinic Acid Ameliorates Neuroinflammation Linked Depressive Behavior Instigated by Chronic Unpredictable Mild Stress via Triggering BDNF/TrkB Signaling Pathway in Rats

Evidence shows that inflammatory responses may encompass the onset of severe depressive illness. Traditionally used licorice contains 18β-glycyrrhetinic acid (18βGA), which has been demonstrated to reduce inflammation and oxidative stress. This study investigates the antidepressant effects of 18βGA and the underlying mechanism in rats exposed to chronic unpredictable mild stress (CUMS). Wistar rats were exposed to CUMS for 36 consecutive days to establish depression. 18βGA (10, 20, and 50 mg/kg) or fluoxetine was given once daily (from day 30 to day 36). Thereafter, behavior parameters (sucrose preference test, forced-swimming test, open-field test, body weight), pro-inflammatory cytokines, neurotransmitters, adrenocorticotropic hormone (ACTH), corticosterone (CORT), and liver biomarkers were studied. Immunohistochemistry and western blot analyses were conducted to investigate the protein's expression. 18βGA (20 and 50 mg/kg) treatment increased sucrose intake, locomotion in the open-field test, decreased immobility time in the forced swim test, and improved body weight in CUMS-exposed rats. The therapy of 18βGA dramatically declined cytokines, ACTH and CORT and improved 5HT and norepinephrine in CUMS rats. Furthermore, BDNF and TrkB proteins were down-regulated in CUMS group, which was increased to varying degrees by 18βGA at doses of 20 and 50 mg/kg. Therefore, 18βGA ameliorates depressive-like behavior persuaded by chronic unpredictable mild stress, decreases neuroinflammation, liver biomarkers, stress hormones, and improves body weight, brain neurotransmitter concentration via activating on BDNF/TrkB signaling pathway in both PFC and hippocampus in rats.

Blocking the ErbB pathway during adolescence affects the induction of anxiety-like behavior in young adult maternal immune activation offspring

Epidemiological and experimental evidence demonstrates that maternal exposure to infection during gestation increases the offspring's risk of developing schizophrenia and other neurodevelopmental disorders. In addition, the NRG-ErbB4 signaling pathway is involved in brain development and neuropsychiatric disorders. Specifically, this pathway modulates the dopaminergic and GABAergic systems and is expressed in the early stages of prenatal development. We recently demonstrated that maternal immune activation (MIA) at late gestation altered the expression of NRG1, its receptor ErbB4, and the dopamine D2 receptor four hours post-injection of viral or LPS in the fetal brain. We also reported that blocking the ErbB pathway during adolescence resulted in increased striatal DA content and reduced preference for sweetness and alcohol that persists into adulthood. However, the combined effects of MIA, re-activation of the immune system, and disruption of the ErbB signaling during adolescence would affect young adult mice's behavioral phenotype is unknown. Here, we report that the expression levels of the NRG1, ErbB4, GAD₆₇, and BDNF were changed as responses to MIA and blocked the ErbB signaling in the frontal cortex of adolescent mice. MIA-Offspring during late gestation and immune system re-activation during adolescence spent less time in the open arms of the elevated plus-maze in adulthood. At the same time, MIA-offspring administrated with the pan-ErbB inhibitor during adolescence spent the same amount of time in the opened arm as the control mice. Combining the ErbB signaling disruption during adolescence leads to a social interaction impairment in female offspring, but not male, without affecting the offspring's motor activity, long-term recognition, and working memory. These results imply that blocking the ErbB signaling during adolescence prevents the development of anxiety-like behavior of the MIA offspring later in life and suggest that this interaction does not reduce the risk of female MIA offspring developing impaired social behavior.

Dietary Methionine via Dose-Dependent Inhibition of Short-Chain Fatty Acid Production Capacity Contributed to a Potential Risk of Cognitive Dysfunction in Mice

High-methionine diets induce impaired learning and memory function, dementia-like neurodegeneration, and Alzheimer's disease, while low-methionine diets improve learning and memory function. We speculated that variations in intestinal microbiota may mediate these diametrically opposed effects; thus, this study aimed to verify this hypothesis. The ICR mice were fed either a low-methionine diet (LM, 0.17% methionine), normal methionine diet (NM, 0.86% methionine), or high-methionine diet (HM, 2.58% methionine) for 11 weeks. We found that HM diets damaged nonspatial recognition memory, working memory, and hippocampus-dependent spatial memory and induced anxiety-like behaviors in mice. LM diets improved nonspatial recognition memory and hippocampus-dependent spatial memory and ameliorated anxiety-like behavior, but the differences did not reach a significant level. Moreover, HM diets significantly decreased the abundance of putative short-chain fatty acid (SCFA)-producing bacteria (Roseburia, Blautia, Faecalibaculum, and Bifidobacterium) and serotonin-producing bacteria (Turicibacter) and significantly increased the abundance of proinflammatory bacteria Escherichia-Shigella. Of note, LM diets reversed the results. Consequently, the SCFA and serotonin levels were significantly decreased with HM diets and significantly increased with LM diets. Furthermore, HM diets induced hippocampal oxidative stress and inflammation and selectively downregulated the hippocampus-dependent memory-related gene expression, whereas LM diets selectively upregulated the hippocampus-dependent memory-related gene expression. In conclusion, dietary methionine via dose-dependent inhibition of SCFA production capacity contributed to a potential risk of cognitive dysfunction in mice.

Mechanisms Underlying Cognitive Impairment Induced by Prenatal Alcohol Exposure

Alcohol is one of the most commonly used illicit substances among pregnant women. Clinical and experimental studies have revealed that prenatal alcohol exposure affects fetal brain development and ultimately results in the persistent impairment of the offspring's cognitive functions. Despite this, the rate of alcohol use among pregnant women has been progressively increasing. Various aspects of human and animal behavior, including learning and memory, are dependent on complex interactions between multiple mechanisms, such as receptor function, mitochondrial function, and protein kinase activation, which are especially vulnerable to alterations during the developmental period. Thus, the exploration of the mechanisms that are altered in response to prenatal alcohol exposure is necessary to develop an understanding of how homeostatic imbalance and various long-term neurobehavioral impairments manifest following alcohol abuse during pregnancy. There is evidence that prenatal alcohol exposure results in vast alterations in mechanisms such as long-term potentiation, mitochondrial function, and protein kinase activation in the brain of offspring. However, to the best of our knowledge, there are very few recent reviews that focus on the cognitive effects of prenatal alcohol exposure and the associated mechanisms. Therefore, in this review, we aim to provide a comprehensive summary of the recently reported alterations to various mechanisms following alcohol exposure during pregnancy, and to draw potential associations with behavioral changes in affected offspring.

Stress, mental disorder and ketamine as a novel, rapid acting treatment

The experience of stress is often utilised in models of emerging mental illness and neurobiological systems are implicated as the intermediary link between the experience of psychological stress and the development of a mental disorder. Chronic stress and prolonged glucocorticoid exposure have potent effects on neuronal architecture particularly in regions that modulate the hypothalamic-pituitary-adrenal (HPA) axis and are commonly associated with psychiatric disorders. This review provides an overview of stress modulating neurobiological and neurochemical systems which underpin stress-related structural and functional brain changes. These changes are thought to contribute not only to the development of disorders, but also to the treatment resistance and chronicity seen in some of our most challenging mental disorders. Reports to date suggest that stress-related psychopathology is the aetiological mechanism of these disorders and thus we review the rapid acting antidepressant ketamine as an effective emerging treatment. Ketamine, an N-methyl D-aspartate (NMDA) receptor antagonist, is shown to induce a robust treatment effect in mental disorders via enhanced synaptic strength and connectivity in key brain regions. Whilst ketamine's glutamatergic effect has been previously examined, we further consider ketamine's capacity to modulate the HPA axis and associated pathways.

Acute Stress Induces Different Changes on the Expression of BDNF and trkB in the Mesocorticolimbic System of Two Lines of Rats Differing in Their Response to Stressors

The present work was undertaken to investigate the effects of acute forced swimming (FS) on the levels of brain-derived neurotrophic factor (BDNF) and tyrosine kinase receptor B (trkB) proteins in: the ventral tegmental area (VTA); the nucleus accumbens (Acb) shell and core compartments; and the anterior cingulate (ACg), prelimbic (PL) and infralimbic (IL) territories of the prefrontal cortex of genetic models of vulnerability (RLA, Roman low-avoidance rats) and resistance (RHA, Roman high-avoidance rats) to stress-induced depression. We report for the first time that FS induced very rapid and distinct changes in the levels of BDNF and trkB proteins in different areas of the mesocorticolimbic system of RHA and RLA rats. Thus, (1) in the VTA and Acb core, FS elicited a significant increase of both BDNF- and trkB-LI in RHA but not RLA rats, whereas in the Acb shell no significant changes in BDNF- and trkB-LI across the line and treatment were observed; (2) in RLA rats, the basal levels of BDNF-LI in the IL/PL cortex and of trkB-LI in the ACg cortex were markedly lower than those of RHA rats; moreover, BDNF- and trkB-LI in the IL/PL and ACg cortex were increased by FS in RLA rats but decreased in their RHA counterparts. These results provide compelling evidence that the genetic background influences the effects of stress on BDNF/trkB signaling and support the view that the same stressor may impact differently on the expression of BDNF in discrete brain areas.

Evaluation of HIF-1 Involvement in the BDNF and ProBDNF Signaling Pathways among Obstructive Sleep Apnea Patients

Obstructive Sleep Apnea (OSA) is a chronic condition characterized by intermittent hypoxia associated with multiple comorbidities, including psychiatric disorders, such as depression, insomnia, and cognitive impairment. The brain-derived neurotrophic factor (BDNF) and proBDNF singling pathways have been shown to be involved in this group of diseases. Furthermore, their expression might be affected by hypoxia-inducible factor 1 (HIF-1), which is an oxygen sensitive transcription factor due to its alpha subunit. Therefore, this study aimed to evaluate the association between HIF-1α, BDNF, and proBDNF protein levels among OSA patients. This study included 40 individuals who underwent polysomnography (PSG) and were divided into the OSA group (n = 20; AHI ≥ 30) and healthy control (n = 20; AHI < 5) based on the apnea−hypopnea index (AHI). All participants had their peripheral blood collected in the evening before and the morning after the PSG. BDNF, proBDNF, and HIF-1α protein concertation measurements were performed using ELISA. No differences were found in BDNF, proBDNF, and HIF-1α protein levels between OSA and the control group, both in the evening and in the morning. In the OSA group, i.e., the linear regression model, the morning BDNF protein level was predicted by age (ß = −0.389, p = 0.023) and the mean SpO2 of desaturations during sleep (ß = −0.577, p = 0.002). This model accounted for 63.3% of the variability in the morning BDNF protein level (F = 14.639, p < 0.001). The morning proBDNF protein level was predicted by age (ß = −0.395, p = 0.033) and HIF-1α morning protein level (ß = −3.192, p = 0.005). This model accounted for 52.4% of the variability in the morning BDNF protein level (F = 9.355, p = 0.002). The obtained results suggest that the HIF-1 transcription factor might be involved in the pathway activated by proBDNF, which may have protective properties from hypoxia in OSA patients.

Function of brain-derived neurotrophic factor in the hypothalamus: Implications for depression pathology

Depression is a prevalent mental health disorder and is the number one cause of disability worldwide. Risk factors for depression include genetic predisposition and stressful life events, and depression is twice as prevalent in women compared to men. Both clinical and preclinical research have implicated a critical role for brain-derived neurotrophic factor (BDNF) signaling in depression pathology as well as therapeutics. A preponderance of this research has focused on the role of BDNF and its primary receptor tropomyosin-related kinase B (TrkB) in the cortex and hippocampus. However, much of the symptomatology for depression is consistent with disruptions in functions of the hypothalamus including changes in weight, activity levels, responses to stress, and sociability. Here, we review evidence for the role of BDNF and TrkB signaling in the regions of the hypothalamus and their role in these autonomic and behavioral functions associated with depression. In addition, we identify areas for further research. Understanding the role of BDNF signaling in the hypothalamus will lead to valuable insights for sex- and stress-dependent neurobiological underpinnings of depression pathology.

Tanshinone IIA ameliorates chronic unpredictable mild stress-induced depression-like behavior and cognitive impairment in rats through the BDNF/TrkB/GAT1 signaling pathway

BACKGROUND

Depression is a common disorder with a complex pathogenesis. Tanshinone IIA (TAN IIA) is a botanical agent with neuroprotective and antidepressant properties.

OBJECTIVE

To examine the effects of TAN IIA on chronic unpredictable mild stress (CUMS)-induced depression-like behavior and cognitive impairment in rats.

METHODS

Rats were exposed to CUMS for 4 weeks, followed by the oral administration of TAN IIA, Deanxit (DEAN), or normal saline for an additional 4 weeks. The control rats were fed with regular chow and administered with normal saline for 4 weeks. Behavioral tests were performed to assess the effects of TAN IIA on depression-like behavior and cognitive impairment in rats with CUMS. The morphology of dendrites was analyzed by Golgi staining. Immunofluorescence staining was performed to determine protein localization.

RESULTS

TAN IIA treatment ameliorated CUMS-induced depression-like behavior and cognitive impairment in rats. TAN IIA treatment also reversed the effects of CUMS on dendritic complexity and the levels of gamma-aminobutyric acid (GABA) in the hippocampus and prefrontal cortex. Rats with CUMS showed decreased levels of brain-derived neurotrophic factor (BDNF) and phosphorylated tropomyosin receptor kinase B (TrkB), upregulated expression of GABA transporter 1 (GAT1), and reduced expression of synaptic proteins in the hippocampus, while TAN IIA treatment significantly diminished the effects of CUMS exposure. In addition, GAT1 was colocalized with N-methyl-D-aspartate receptor 2B.

CONCLUSION

TAN IIA ameliorates CUMS-induced depression-like behavior and cognitive impairment in rats by regulating the BDNF/TrkB/GAT1 signaling pathway, suggesting that TAN IIA may be a candidate drug for the treatment of depression.

Correlating electroconvulsive therapy response to electroencephalographic markers: Study protocol

Introduction

Electroconvulsive therapy (ECT) is an effective intervention for patients with major depressive disorder (MDD). Despite longstanding use, the underlying mechanisms of ECT are unknown, and there are no objective prognostic biomarkers that are routinely used for ECT response. Two electroencephalographic (EEG) markers, sleep slow waves and sleep spindles, could address these needs. Both sleep microstructure EEG markers are associated with synaptic plasticity, implicated in memory consolidation, and have reduced expression in depressed individuals. We hypothesize that ECT alleviates depression through enhanced expression of sleep slow waves and sleep spindles, thereby facilitating synaptic reconfiguration in pathologic neural circuits.

Methods

Correlating ECT Response to EEG Markers (CET-REM) is a single-center, prospective, observational investigation. Wireless wearable headbands with dry EEG electrodes will be utilized for at-home unattended sleep studies to allow calculation of quantitative measures of sleep slow waves (EEG SWA, 0.5-4 Hz power) and sleep spindles (density in number/minute). High-density EEG data will be acquired during ECT to quantify seizure markers.

Discussion

This innovative study focuses on the longitudinal relationships of sleep microstructure and ECT seizure markers over the treatment course. We anticipate that the results from this study will improve our understanding of ECT.

Brain-Derived Neurotrophic Factor (BDNF) as a biomarker of treatment response in patients with Treatment Resistant Depression (TRD): A systematic review & meta-analysis

Multiple lines of evidence have implicated brain-derived neurotrophic factor (BDNF) in treatment-resistant depression (TRD). The aim of this synthesis was to determine the impact of TRD treatments on peripheral BDNF levels, and ascertain whether these changes are associated with antidepressant effects. Thirty-six articles involving 1198 patients with TRD were included herein. Electroconvulsive therapy (ECT), ketamine, and repetitive transcranial magnetic stimulation (rTMS) were the most common TRD treatments investigated. Serum BDNF levels significantly increased in six, two, four and one studies following ECT, ketamine, rTMS and atypical antipsychotics, respectively. The estimated mean baseline serum BDNF concentration in TRD patients ± 95% CI was 15.5 ± 4.34 ng/mL. Peripheral BDNF levels significantly increased overall (Hedges' g ± 95% CI = 0.336 ± 0.302; p < 0.05), but no association with depressive symptoms was found (p ≥ 0.05). These results demonstrate that peripheral measurements of total BDNF (i.e., mature and percursor forms of BDNF) are inadequate predictors of treatment response in TRD patients, and other considerations suggest that this would still apply to separable measurements of mature BDNF and its precursor.