Interaction between BDNF and serotonin: role in mood disorders

Perinatal Exposure to Diesel Exhaust-Origin Secondary Organic Aerosol Induces Autism-Like Behavior in Rats

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social communication, poor social interactions, and repetitive behaviors. We aimed to examine autism-like behaviors and related gene expressions in rats exposed to diesel exhaust (DE)-origin secondary organic aerosol (DE-SOA) perinatally. Sprague–Dawley pregnant rats were exposed to clean air (control), DE, and DE-SOA in the exposure chamber from gestational day 14 to postnatal day 21. Behavioral phenotypes of ASD were investigated in 10~13-week-old offspring using a three-chambered social behavior test, social dominance tube test, and marble burying test. Prefrontal cortex was collected to examine molecular analyses including neurological and immunological markers and glutamate concentration, using RT-PCR and ELISA methods. DE-SOA-exposed male and female rats showed poor sociability and social novelty preference, socially dominant behavior, and increased repetitive behavior. Serotonin receptor (5-HT(5B)) and brain-derived neurotrophic factor (BDNF) mRNAs were downregulated whereas interleukin 1 β (IL-β) and heme oxygenase 1 (HO-1) mRNAs were upregulated in the prefrontal cortex of male and female rats exposed to DE-SOA. Glutamate concentration was also increased significantly in DE-SOA-exposed male and female rats. Our results indicate that perinatal exposure to DE-SOA may induce autism-like behavior by modulating molecules such as neurological and immunological markers in rats.

Psychedelics and Neuroplasticity: A Systematic Review Unraveling the Biological Underpinnings of Psychedelics

Clinical studies suggest the therapeutic potential of psychedelics, including ayahuasca, DMT, psilocybin, and LSD, in stress-related disorders. These substances induce cognitive, antidepressant, anxiolytic, and antiaddictive effects suggested to arise from biological changes similar to conventional antidepressants or the rapid-acting substance ketamine. The proposed route is by inducing brain neuroplasticity. This review attempts to summarize the evidence that psychedelics induce neuroplasticity by focusing on psychedelics' cellular and molecular neuroplasticity effects after single and repeated administration. When behavioral parameters are encountered in the selected studies, the biological pathways will be linked to the behavioral effects. Additionally, knowledge gaps in the underlying biology of clinical outcomes of psychedelics are highlighted. The literature searched yielded 344 results. Title and abstract screening reduced the sample to 35; eight were included from other sources, and full-text screening resulted in the final selection of 16 preclinical and four clinical studies. Studies (n = 20) show that a single administration of a psychedelic produces rapid changes in plasticity mechanisms on a molecular, neuronal, synaptic, and dendritic level. The expression of plasticity-related genes and proteins, including Brain-Derived Neurotrophic Factor (BDNF), is changed after a single administration of psychedelics, resulting in changed neuroplasticity. The latter included more dendritic complexity, which outlasted the acute effects of the psychedelic. Repeated administration of a psychedelic directly stimulated neurogenesis and increased BDNF mRNA levels up to a month after treatment. Findings from the current review demonstrate that psychedelics induce molecular and cellular adaptations related to neuroplasticity and suggest those run parallel to the clinical effects of psychedelics, potentially underlying them. Future (pre)clinical research might focus on deciphering the specific cellular mechanism activated by different psychedelics and related to long-term clinical and biological effects to increase our understanding of the therapeutic potential of these compounds.

Altered GABA-mediated information processing and cognitive dysfunctions in depression and other brain disorders

Cognitive dysfunctions, including impaired attention, learning, memory, planning and problem solving, occur in depressive episodes, often persist during remission, predict relapse, worsen with recurrent episodes, and are not treated by current antidepressants or other medications. Cognitive symptoms are also present in other psychiatric disorders, are a hallmark of aging, and define several late-life disorders, including Alzheimer's disease. This pervasive occurrence suggests either a non-specific outcome of a diseased brain, or a shared underlying pathology contributing to this symptom dimension. Recent findings suggest a role for altered GABAergic inhibition in cognitive symptoms. Cellular, molecular and biochemical studies in human subjects report changes affecting the gamma-amino butyric acid (GABA) system, specifically somatostatin-expressing (SST+) GABAergic interneurons, across brain disorders and during aging. SST+ neurons gate excitatory input onto pyramidal neurons within cortical microcircuits. Experimentally reducing the function of these neurons affects excitatory signal-to-noise ratio, reduces synchronized cellular and neural activity, and leads to cognitive dysfunctions. Conversely, augmenting SST+ cell post-synaptic α5-GABA-A receptor activity has pro-cognitive efficacy in stress and aging models. Together, this suggests that reduced signaling of the SST+ neuron/α5-GABA-A receptor pathway contributes to cognitive dysfunctions, and that it represents a novel therapeutic target for remediating mood and cognitive symptoms in depression, other psychiatric disorders and during aging.

Psychedelics in Psychiatry: Neuroplastic, Immunomodulatory, and Neurotransmitter Mechanisms

Mounting evidence suggests safety and efficacy of psychedelic compounds as potential novel therapeutics in psychiatry. Ketamine has been approved by the Food and Drug Administration in a new class of antidepressants, and 3,4-methylenedioxymethamphetamine (MDMA) is undergoing phase III clinical trials for post-traumatic stress disorder. Psilocybin and lysergic acid diethylamide (LSD) are being investigated in several phase II and phase I clinical trials. Hence, the concept of psychedelics as therapeutics may be incorporated into modern society. Here, we discuss the main known neurobiological therapeutic mechanisms of psychedelics, which are thought to be mediated by the effects of these compounds on the serotonergic (via 5-HT_2A and 5-HT_1A receptors) and glutamatergic [via N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors] systems. We focus on 1) neuroplasticity mediated by the modulation of mammalian target of rapamycin-, brain-derived neurotrophic factor-, and early growth response-related pathways; 2) immunomodulation via effects on the hypothalamic-pituitary-adrenal axis, nuclear factor ĸB, and cytokines such as tumor necrosis factor-α and interleukin 1, 6, and 10 production and release; and 3) modulation of serotonergic, dopaminergic, glutamatergic, GABAergic, and norepinephrinergic receptors, transporters, and turnover systems. We discuss arising concerns and ways to assess potential neurobiological changes, dependence, and immunosuppression. Although larger cohorts are required to corroborate preliminary findings, the results obtained so far are promising and represent a critical opportunity for improvement of pharmacotherapies in psychiatry, an area that has seen limited therapeutic advancement in the last 20 years. Studies are underway that are trying to decouple the psychedelic effects from the therapeutic effects of these compounds. SIGNIFICANCE STATEMENT: Psychedelic compounds are emerging as potential novel therapeutics in psychiatry. However, understanding of molecular mechanisms mediating improvement remains limited. This paper reviews the available evidence concerning the effects of psychedelic compounds on pathways that modulate neuroplasticity, immunity, and neurotransmitter systems. This work aims to be a reference for psychiatrists who may soon be faced with the possibility of prescribing psychedelic compounds as medications, helping them assess which compound(s) and regimen could be most useful for decreasing specific psychiatric symptoms.

Exploring the effectiveness of a specialized therapy programme for burnout using subjective report and biomarkers of stress

The increasing prevalence of stress-related disorders such as burnout urges the need for specialized treatment approaches. Programmes combining psychotherapy and regenerative interventions emerge to be the most successful. However, evaluated therapy programmes are scarce and usually involve subjective symptom quantification without consideration of physiologic parameters. The aim of the present exploratory, single-group study was the multimodal investigation of the effectiveness of a specialized holistic therapy programme by assessing symptoms and biological markers of chronic stress. Seventy-one in-patients (39 men/32 women; age 46.8 ± 9.9 years) of a specialized burnout ward with the additional diagnosis of burnout (Z73.0) in conjunction with a main diagnosis of depressive disorder (F32 or F33) according to the International Classification of Diseases (ICD)-10 were included in the study. In addition to symptomatology, the stress-responsive biomarkers heart rate variability (HRV) and serum brain-derived neurotrophic factor (BDNF) were measured in patients at admittance to and discharge from the burnout ward applying a 6-week specialized treatment programme. At discharge, patients showed a significant reduction of symptom burden and a significant increase in serum BDNF, while HRV remained unchanged. The findings implicate that the therapy programme may have beneficial effects on symptomatology and neuroplasticity of patients with burnout. As therapy was often supplemented by psychopharmacological treatment, a relevant influence of antidepressant medication especially on BDNF has to be considered.

Of adenosine and the blues: The adenosinergic system in the pathophysiology and treatment of major depressive disorder

Major depressive disorder (MDD) is the foremost cause of global disability, being responsible for enormous personal, societal, and economical costs. Importantly, existing pharmacological treatments for MDD are partially or totally ineffective in a large segment of patients. As such, the search for novel antidepressant drug targets, anchored on a clear understanding of the etiological and pathophysiological mechanisms underpinning MDD, becomes of the utmost importance. The adenosinergic system, a highly conserved neuromodulatory system, appears as a promising novel target, given both its regulatory actions over many MDD-affected systems and processes. With this goal in mind, we herein review the evidence concerning the role of adenosine as a potential player in pathophysiology and treatment of MDD, combining data from both human and animal studies. Altogether, evidence supports the assertions that the adenosinergic system is altered in both MDD patients and animal models, and that drugs targeting this system have considerable potential as putative antidepressants. Furthermore, evidence also suggests that modifications in adenosine signaling may have a key role in the effects of several pharmacological and non-pharmacological antidepressant treatments with demonstrated efficacy, such as electroconvulsive shock, sleep deprivation, and deep brain stimulation. Lastly, it becomes clear from the available literature that there is yet much to study regarding the role of the adenosinergic system in the pathophysiology and treatment of MDD, and we suggest several avenues of research that are likely to prove fruitful.

Anti-depressant effect of cerebrolysin in reserpine-induced depression in rats: Behavioral, biochemical, molecular and immunohistochemical evidence

Depression is a major psychological disorder that contributes to global health problem. This study aimed to evaluate the anti-depressant effect of Cerebrolysin (CBL) in Reserpine-induced depressed rats, its effect on oxidative stress, inflammation, regulatory cyclic AMP-dependent response element binding protein (CREB)/brain derived neurotropic factor (BDNF) signaling pathways, brain monoamines and histopathological changes was assessed. Rats received either the vehicle or Reserpine (0.5 mg/kg, i.p.) for 14 days. The other three groups were pretreated with CBL (2.5, 5 ml/kg; i.p.) or fluoxetine (FLU) (5 mg/kg, p.o.), respectively for 14 days, 30 min before reserpine injection. Then analyses were conducted. CBL reversed Reserpine-induced reduction in latency to immobility and prolongation of immobility time in the forced swimming test (FST), reduced malondialdehyde (MDA), elevated reduced glutathione (GSH), reduced tumor necrosis factor-alpha (TNF-ɑ), and elevated BDNF cortical and hippocampal brain contents. CBL elevated protein kinase A (PKA) and nuclear factor kappa-B (NF-κB) cortical and hippocampal protein expressions. CBL also ameliorated alterations in mRNA expressions of protein kinase B (AKT), CREB and BDNF in the cortical and hippocampal tissues. CBL elevated nor-epinephrine (NE), serotonin (5-HT), and dopamine (DA) and reduced 5-Hydroxyindoleacetic acid (5-HTAA), 3,4-Dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) cortical and hippocampal contents. CBL effects were in parallel to those observed with the standard anti-depressant drug, FLU. This study shows that CBL exerted anti-depressant effect evidenced by attenuation of oxidative stress and inflammation as well as enhancement of neurogenesis, amelioration of monoaminergic system and histopathological changes.

Perinatal fluoxetine treatment promotes long-term behavioral changes in adult mice

Serotonin exerts a significant role in the mammalian central nervous system embryogenesis and brain ontogeny. Therefore, we investigate the effect of perinatal fluoxetine (FLX), a selective serotonin reuptake inhibitor, administration on the behavioral expression of adult male Swiss mice. For this purpose, two groups (n = 6 each, and ~ 35 g) of pregnant female Swiss mice were mated. Their offspring were treated with FLX (10 mg/Kg, s.c.) from postnatal day (PND) 5 to 15. At PND 16, one male puppy of each litter was euthanized, and the hippocampus was dissected for RNA analysis. At 70 days of life, the male offspring underwent a behavioral assessment in the open field, object recognition task, light-dark box, tail suspension and rotarod test. According to our results, the programmed animals had a decrease in TPH2, 5HT1a, SERT, BDNF, and LMX1B expression. Also, it was observed less time of immobility in tail suspension test and higher grooming time in the open field test. In the light-dark box test, the FLX-treated offspring had less time in the light side than control. We also observed a low cognitive performance in the object recognition task and poor motor skill learning in the rotarod test. These findings suggest that programming with FLX during the neonatal period alters a hippocampal serotonergic system, promoting anxiety and antidepressant behavior in adults, as well as a low mnemonic capacity.

Candidate metabolic biomarkers for schizophrenia in CNS and periphery: Do any possible associations exist?

Due to the limitations of analytical techniques and the complicity of schizophrenia, nowadays it is still a challenge to diagnose and stratify schizophrenia patients accurately. Many attempts have been made to identify and validate available biomarkers for schizophrenia from CSF and/or peripheral blood in clinical studies with consideration to disease stages, antipsychotic effects and even gender differences. However, conflicting results handicap the validation and application of biomarkers for schizophrenia. In view of availability and feasibility, peripheral biomarkers have superior advantages over biomarkers in CNS. Meanwhile, schizophrenia is considered to be a devastating neuropsychiatric disease mainly taking place in CNS featured by widespread defects in multiple metabolic pathways whose dynamic interactions, until recently, have been difficult to difficult to investigate. Evidence for these alterations has been collected piecemeal, limiting the potential to inform our understanding of the interactions among relevant biochemical pathways. Taken these points together, it will be interesting to investigate possible associations of biomarkers between CNS and periphery. Numerous studies have suggested putative correlations within peripheral and CNS systems especially for dopaminergic and glutamatergic metabolic biomarkers. In addition, it has been demonstrated that blood concentrations of BDNF protein can also reflect its changes in the nervous system. In turn, BDNF also interacts with glutamatergic, dopaminergic and serotonergic systems. Therefore, this review will summarize metabolic biomarkers identified both in the CNS (brain tissues and CSF) and peripheral blood. Further, more attentions will be paid to discussing possible physical and functional associations between CNS and periphery, especially with respect to BDNF.

Unfolding the Role of BDNF as a Biomarker for Treatment of Depression

Depression is a well-known disabling mental illness characterized by sadness, loss of interest in activities, and decreased energy. The symptoms of depression are usually recurrent in vulnerable individuals, and persistence of symptoms significantly impairs individuals' quality of life. The exact pathophysiology of depression remains ambiguous, though many hypotheses have been proposed. Brain-derived neurotrophic factor (BDNF) has recently been reported to play a vital role in the pathophysiology of depression. BDNF is an important neurotrophic factor found in the human brain and is involved in neuronal growth and proliferation, synaptic neurotransmission, and neuroplasticity. The neurotrophic theory of depression proposes that depression results from reduced BDNF levels in the brain, which can be treated with antidepressants to alleviate depressive behavior and increase BDNF levels. The aim of this review is to provide broad insight into the role of BDNF in the pathogenesis of depression and in antidepressant therapy. The studies mentioned in this review article greatly support the role of BDNF in the pathogenesis of depression and treatment of this disorder with antidepressants. Since abnormalities in BDNF levels lead to the production of diverse insults that amplify the development or progression of depression, it is important to study and explore BDNF impairment in relation to depression, neuroplasticity, and neurogenesis, and increasing BDNF levels through antidepressant therapy, showing positive response in the management of depression.

Expression analysis of BDNF, BACE1 and their antisense transcripts in inflammatory demyelinating polyradiculoneuropathy

Acute and chronic inflammatory demyelinating polyradiculoneuropathies (AIDP and CIDP) are two immune-related conditions in the peripheral nervous system. In the current study, we assessed expression levels of Beta-secretase (BACE1), brain-derived neurotrophic factor (BDNF) and their antisense transcripts in the peripheral blood of AIDP and CIDP patients compared with age- and sex-matched controls to assess their potential as biomarkers for these conditions. Expressions of BACE1 and BACE1-AS were down-regulated in CIDP cases compared with controls (Ratios of mean expressions=0.01 and 0.03; P values= 1.07E-08, respectively). On the other hand, expressions of BDNF and BDNF-AS were up-regulated in CIDP cases compared with controls (Ratios of mean expressions=4.78 and 25.71; P values= 7.84E-03 and 2.66E-07, respectively). Expressions of BACE1 and BACE1-AS were lower in AIDP cases compared with controls (Ratios of mean expressions=0.00; P values= 6.92E-10 and 8.04E-10, respectively). While expression of BDNF was not different between AIDP cases and controls, expression of its antisense transcript was higher in total AIDP cases compared with total controls (Ratio of mean expression= 8.61, P value=3.69E-04). Expressions of BACE1-AS, BDNF and BDNF-AS were significantly higher in CIDP cases compared with AIDP cases (Ratios of mean expression=1.98, 3.49 and 2.99; P values=4.67E-02, 4.67E-04 and 8.94E-03 respectively). Expression levels of BACE1, BACE1-AS and BDNF-AS could distinguish AIDP and CIDP cases from healthy subjects. BACE1 had the best diagnostic values in differentiation of CIDP and AIDP cases from controls (AUC values=0.88 and 0.91, respectively). Combination of all genes enhanced the diagnostic power to 0.96, 0.97 and 0.97 for differentiation between CIDP/controls, AIDP/controls and all patients/controls, respectively. Taken together, these genes might be implicated in the pathogenesis of AIDP and CIDP and can be suggested as putative markers for these conditions.

The effect of insomnia on development of Alzheimer's disease

Alzheimer's disease (AD) is the most common type of dementia and a neurodegenerative disorder characterized by memory deficits especially forgetting recent information, recall ability impairment, and loss of time tracking, problem-solving, language, and recognition difficulties. AD is also a globally important health issue but despite all scientific efforts, the treatment of AD is still a challenge. Sleep has important roles in learning and memory consolidation. Studies have shown that sleep deprivation (SD) and insomnia are associated with the pathogenesis of Alzheimer's disease and may have an impact on the symptoms and development. Thus, sleep disorders have decisive effects on AD; this association deserves more attention in research, diagnostics, and treatment, and knowing this relation also can help to prevent AD through screening and proper management of sleep disorders. This study aimed to show the potential role of SD and insomnia in the pathogenesis and progression of AD.

Oral contraceptives and the serotonin 4 receptor: a molecular brain imaging study in healthy women

OBJECTIVE

Sex steroid hormones potently shape brain functions, including those critical to maintain mental health such as serotonin signaling. Use of oral contraceptives (OCs) profoundly changes endogenous sex steroid hormone levels and dynamics. Recent register-based studies show that starting an OC is associated with increased risk of developing depression. Here, we investigate whether use of OCs in healthy women is associated with a marker of the serotonin system in terms of serotonin 4 receptor (5-HT4R) brain imaging.

METHODS

[11C]SB207145-PET imaging data on 53 healthy women, of whom 16 used OCs, were available from the Cimbi database. We evaluated global effects of OC use on 5-HT4R binding in a latent variable model based on 5-HT4R binding across cortical and subcortical regions.

RESULTS

We demonstrate that OC users have 9-12% lower global brain 5-HT4R binding potential compared to non-users. Univariate region-based analyses (pallidostriatum, caudate, hippocampus, amygdala, anterior cingulate cortex, and neocortex) supported the global effect of OC use with the largest difference present in the hippocampus (-12.8% (95% CI [-21.0; -3.9], Pcorrected = 0.03).

CONCLUSION

We show that women who use OCs have markedly lower brain 5-HT4R binding relative to non-users, which constitutes a plausible molecular link between OC use and increased risk of depressive episodes. We propose that this reflects a reduced 5-HT4R gene expression, possibly related to a blunted ovarian hormone state among OC users.

Psychological and neurobiological aspects of suicide in adolescents: Current outlooks

Suicidality is one of the leading causes of death among young adults in the United States and represents a significant health problem worldwide. The suicide rate among adolescents in the United States has increased dramatically in the latest years and has been accompanied by considerable changes in youth suicide, especially among young girls. Henceforth, we need a good understanding of the risk factors contributing to suicidal behavior in youth. An explanatory model for suicidal behavior that links clinical and psychological risk factors to the underlying neurobiological, neuropsychological abnormalities related to suicidal behavior might predict to help identify treatment options and have empirical value. Our explanatory model proposes that developmental, biological factors (genetics, proteomics, epigenetics, immunological) and psychological or clinical (childhood adversities) may have causal relevance to the changes associated with suicidal behavior. In this way, our model integrates findings from several perspectives in suicidality and attempts to explain the relationship between various neurobiological, genetic, and clinical observations in suicide research, offering a comprehensive hypothesis to facilitate understanding of this complex outcome. Unraveling the knowledge of the complex interplay of psychological, biological, sociobiological, and clinical risk factors is highly essential, concerning the development of effective prevention strategy plans for suicidal ideation and suicide.

The Wistar-Kyoto rat model of endogenous depression: A tool for exploring treatment resistance with an urgent need to focus on sex differences

Major depressive disorder (MDD) is one of the leading causes of years lived with disability and contributor to the burden of disease worldwide. The incidence of MDD has increased by ~20% in the last decade. Currently antidepressant drugs such as the popular selective serotonin reuptake inhibitors (SSRIs) are the leading form of pharmaceutical intervention for the treatment of MDD. SSRIs however, are inefficient in ameliorating depressive symptoms in ~50% of patients and exhibit a prolonged latency of efficacy. Due to the burden of disease, there is an increasing need to understand the neurobiology underpinning MDD and to discover effective treatment strategies. Endogenous models of MDD, such as the Wistar-Kyoto (WKY) rat provide a valuable tool for investigating the pathophysiology of MDD. The WKY rat displays behavioural and neurobiological phenotypes similar to that observed in clinical cases of MDD, as well as resistance to common antidepressants. Specifically, the WKY strain exhibits increased anxiety- and depressive-like behaviours, as well as alterations in Hypothalamic Pituitary Adrenal (HPA) axis, serotonergic, dopaminergic and neurotrophic systems with emerging studies suggesting an involvement of neuroinflammation. More recent investigations have shown evidence for reduced cortical and hippocampal volumes and altered glutamatergic signalling in the WKY strain. Given the growing interest in therapeutics targeting the glutamatergic system, the WKY strain presents itself as a potentially useful tool for screening novel antidepressant drugs and their efficacy against treatment resistant depression. However, despite the sexual dimorphism present in the pathophysiology and aetiology of MDD, sex differences in the WKY model are rarely investigated, with most studies focusing on males. Accordingly, this review highlights what is known regarding sex differences and where further research is needed. Whilst acknowledging that investigation into a range of depression models is required to fully elucidate the underlying mechanisms of MDD, here we review the WKY strain, and its relevance to the clinic.

Antidepressant and Anti-Neuroinflammatory Effects of Bangpungtongsung-San

Bangpungtongsung-san (BTS) is a traditional Korean medicine consisting of 18 herbs, some which have antidepressant effects. Here, we used an animal model of reserpine-induced depression and lipopolysaccharide (LPS)-stimulated BV2 microglia to assess the antidepressant and anti-neuroinflammatory effects of BTS. Aside from a control group, C57BL/6 mice were administered reserpine (0.5 mg/kg) daily for 10 days via intraperitoneal injection. BTS (100, 300, or 500 mg/kg), vehicle (PBS), or fluoxetine (FXT, 20 mg/kg) was administered orally 1 h before reserpine treatment. Following treatment, a forced swimming test (FST), tail suspension test (TST), and open field test (OFT) were performed, and immobility time and total travel distance were measured. Administration of BTS not only reduced immobility time in the FST and TST but also significantly increased the total travel distance in the OFT. Furthermore, reserpine-treated mice showed significantly elevated serum levels of corticosterone, a stress hormone; however, treatment with BTS significantly reduced corticosterone levels, similar to FXT treatment. Serotonin in reserpine-treated mice was significantly reduced compared to that in control mice, while BTS mice exhibited increased serotonin levels. BTS mice showed increased expression of brain-derived neurotrophic factor (BDNF) and a higher ratio of phosphorylated cAMP response element-binding protein (p-CREB) to CREB (p-CREB/CREB) in the hippocampus. Additionally, reserpine-treated mice exhibited significantly elevated mRNA levels of pro-inflammatory cytokines, but BTS mice showed reduced mRNA levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in the hippocampus. To further demonstrate the anti-neuroinflammatory effects of BTS in vitro, we examined its anti-neuroinflammatory and neuroprotective effects in lipopolysaccharide (LPS)-stimulated BV2 microglia. BTS significantly reduced the levels of NO, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, TNF-α, IL-1β, and IL-6 in a dose-dependent manner via a decrease in the expression of nuclear factor (NF)-κB p65. Furthermore, the neuroprotective factor heme oxygenase-1 (HO-1) was upregulated via the nuclear factor-E2-related factor 2 (NRF2)/CREB pathway. Taken together, our data suggest that BTS has considerable potential as an anti-neuroinflammation and antidepressant agent, as it has clear effects on depressive behaviors and associated factors caused by reserpine-induced depression.

N-3 PUFA Have Antidepressant-like Effects Via Improvement of the HPA-Axis and Neurotransmission in Rats Exposed to Combined Stress

Early life and adulthood stress increase vulnerability for mental illness, and eventually trigger depression. N-3 polyunsaturated fatty acids (PUFA) have antidepressant effects, but their effect on rats exposed to combined stress has been not investigated. This study aimed to investigate whether n-3 PUFA supplementation had antidepressant-like effects in rat models of depression induced by a combination of chronic mild stress (CMS) and maternal separation (MS) through the modulation of the hypothalamic-pituitary-adrenal (HPA) axis and neurotransmission. Rats were fed the n-3 PUFA diet during the pre-weaning or post-weaning period or for lifetime, and allocated to different groups based on the type of induced stress: non-stress (NS), CMS + MS, or CMS alone. N-3 PUFA improved the depressive behaviors of the CMS alone and CMS + MS groups and modulated the HPA-axis by reducing the circulating adrenocorticotropic hormone, corticosterone, and corticotropin-releasing factor expression, and increasing glucocorticoid receptor expression. N-3 PUFA also modulated brain phospholipid fatty acid concentration, thus reducing inflammatory cytokines; improved the serotonergic pathway, thus increasing the expression of the brain-derived neurotrophic factor (BDNF), cAMP response element-binding protein (CREB), serotonin-1A receptor, and serum levels of serotonin; but did not affect glutamatergic neurotransmission. Furthermore, n-3 PUFA decreased the hippocampal expression of microRNA-218 and -132, increased that of microRNA-155, and its lifetime supplementation was more beneficial than pre- or post-weaning supplementation. This study suggests that n-3 PUFA has an antidepressant effect in rats exposed to combined stress, through the improvement of the HPA-axis abnormalities, the BDNF-serotonergic pathway, and the modulation of microRNAs.

Improvement in resilience and stress-related blood markers following ten months yoga practice in Antarctica

BACKGROUND

Wintering is associated with distress to humans who work in the isolated and confined environment of Antarctica and yoga has been proved helpful for coping with stress. Therefore, a study was conducted on 14 winter expedition members of Indian Scientific Antarctic Expedition (2016) to find out the effects of yoga on stress-related markers.

METHODS

Participants were divided into yoga, and control (non-yoga) groups. The yoga group practiced yoga for 10 months (from January to October 2016) daily in the morning for an hour. The Resilience test questionnaire was administrated at baseline and endpoint of the study. Blood samples were collected during the study at different intervals for the estimation of 8-hydroxydeoxyguanosine (8-OHdG), brain-derived neurotrophic factor (BDNF), serotonin and cortisol using ELISA.

RESULTS

A trend of improvement was observed in the resilience test score in the yoga group. From January to October, 8-OHdG serum values in the yoga group declined by 55.9% from 1010.0 ± 67.8 pg/mL to 445.6 ± 60.5 pg/mL (Mean ± SD); in the control group, the decline was 49.9% from 1060.4 ± 54.6 pg/mL to 531.1 ± 81.8 pg/mL. In serotonin serum levels in the yoga group, there was a 3.1% increase from 6.4 ± 1.6 ng/mL to 6.6 ± 0.4 ng/mL while no increase was noticed in the control group. Cortisol values in the yoga group decreased by 19.9% from 321.0 ± 189.6 ng/mL to 257.1 ± 133.8 ng/mL; in the control group it increased by 2.8% from 241.2 ± 51.8 ng/mL to 247.8 ± 90.9 ng/mL.

CONCLUSIONS

It could be concluded from the present study that following 10 months yoga practice may be useful for better resilience and management of stress-related blood markers for the polar sojourners.

NLRP1 inflammasome contributes to chronic stress-induced depressive-like behaviors in mice

BACKGROUND

Major depressive disorder (MDD) is a highly prevalent psychiatric disorder, and inflammation has been considered crucial components of the pathogenesis of depression. NLRP1 inflammasome-driven inflammatory response is believed to participate in many neurological disorders. However, it is unclear whether NLRP1 inflammasome is implicated in the development of depression.

METHODS

Animal models of depression were established by four different chronic stress stimuli including chronic unpredictable mild stress (CUMS), chronic restrain stress (CRS), chronic social defeat stress (CSDS), and repeat social defeat stress (RSDS). Depressive-like behaviors were determined by sucrose preference test (SPT), forced swim test (FST), tail-suspension test (TST), open-field test (OFT), social interaction test (SIT), and light-dark test (LDT). The expression of NLRP1 inflammasome complexes, BDNF, and CXCL1/CXCR2 were tested by western blot and quantitative real-time PCR. The levels of inflammatory cytokines were tested by enzyme-linked immunosorbent assay (ELISA) kits. Nlrp1a knockdown was performed by an adeno-associated virus (AAV) vector containing Nlrp1a-shRNA-eGFP infusion.

RESULTS

Chronic stress stimuli activated hippocampal NLRP1 inflammasome and promoted the release of pro-inflammatory cytokines IL-1β, IL-18, IL-6, and TNF-α in mice. Hippocampal Nlrp1a knockdown prevented NLRP1 inflammasome-driven inflammatory response and ameliorated stress-induced depressive-like behaviors. Also, chronic stress stimuli caused the increase in hippocampal CXCL1/CXCR2 expression and low BDNF levels in mice. Interestingly, Nlrp1a knockdown inhibited the up-regulation of CXCL1/CXCR2 expression and restored BDNF levels in the hippocampus.

CONCLUSIONS

NLRP1 inflammasome-driven inflammatory response contributes to chronic stress induced depressive-like behaviors and the mechanism may be related to CXCL1/CXCR2/BDNF signaling pathway. Thus, NLRP1 inflammasome could become a potential antidepressant target.

Differences between women and men in the relationship between psychosocial stressors at work and work absence due to mental health problem

OBJECTIVES

Women have a higher incidence of mental health problems compared with men. Psychosocial stressors at work are associated with mental health problems. However, few prospective studies have examined the association between these stressors and objectively measured outcomes of mental health. Moreover, evidence regarding potential differences between women and men in this association is scarce and inconsistent. This study investigates whether psychosocial stressors at work are associated with the 7.5-year incidence of medically certified work absence due to a mental health problem, separately for women and men.

METHODS

Data from a prospective cohort of white-collar workers in Canada (n=7138; 47.3% women) were used. We performed Cox regression models to examine the prospective association between self-reported psychosocial stressors at work (job strain model) at baseline and the 7.5-year HR of medically certified work absence of ≥5 days due to a mental health problem.

RESULTS

During follow-up, 11.9% of participants had a certified work absence, with a twofold higher incidence among women. Women (HR 1.40, 95% CI 1.01 to 1.93) and men (HR 1.41, 95% CI 0.97 to 2.05) exposed to high strain (high demands and low control) had a higher incidence of work absence compared with those unexposed. Among women only, those exposed to an active job situation (high demands and high control) also had a higher risk (HR 1.82, 95% CI 1.29 to 2.56).

CONCLUSIONS

Prevention efforts aimed at reducing psychosocial stressors at work could help lower the risk of work absence for both women and men. However, important differences between women and men need to be further studied in order to orient these efforts.

The effects of Engelhardtia chrysolepis Hance on long-term memory and potential dopamine involvement in mice

Engelhardtia chrysolepis Hance (ECH) is a perennial plant used in traditional medicine. A major active ingredient of ECH is astilbin (ASB), which has recently been shown to have neuroprotective effects as well as to affect catecholamine neurotransmissions in brain areas such as the prefrontal cortex. In this study, we investigated the effects of ECH and ASB on long-term memory in mice using a battery of behavioral tests. Acute ECH treatments dose-dependently facilitated nonspatial, but not spatial, memory. ECH treatments also upregulated expression of tyrosine hydroxylase, the enzyme mediating catecholamine synthesis, in neuroblastoma cell culture. Acute ASB treatments similarly improved nonspatial memory, whereas chronic ASB treatments improved both nonspatial and spatial memory. In accordance with such behavioral effects, the increased ratio of tissue concentrations of dopamine metabolites over dopamine in striatal regions was observed in mice with chronic ASB treatments. These results suggest that ECH and its active ingredient ASB may facilitate long-term memory by modulating catecholamine transmission.

Garlic essential oil mediates acute and chronic mild stress-induced depression in rats via modulation of monoaminergic neurotransmission and brain-derived neurotrophic factor levels

Garlic essential oil (GEO) and its major organosulfur component (diallyl disulfide, DADS) possess diverse biological properties; however, limited information on their antidepressant-like effects is available. This study is the first to investigate these effects of GEO using the forced swimming test (FST) and unpredictable chronic mild stress (UCMS) induced depression in rats. After oral administration for 28 consecutive days, GEO (25 and 50 mg per kg bw) significantly reduced the immobility time in the FST. Additionally, GEO and DADS significantly reversed the sucrose preference index decrease induced by 5 weeks of UCMS. GEO (25 mg per kg bw) effectively decreased the frontal cortex turnover ratio of serotonin (5-HT) and dopamine (DA), thus increasing the 5-HT and DA levels, with no hippocampal effects. Chronic GEO treatment increased hippocampal brain-derived neurotrophic factor (BDNF), c-AMP response element binding protein (CREB), and protein kinase B (AKT) expression, exhibiting its effects via monoamine neurotransmitter modulation and the BDNF-related signaling pathway.

Interaction between job stress, serum BDNF level and the BDNF rs2049046 polymorphism in job burnout

BACKGROUND

Some studies have shown that long-term exposure to job stress could result in burnout, and BDNF polymorphism may play an important role in its psychopathological mechanism. However, the inter-relationships between the job-related stress, serum BDNF level, BDNF genotype and job burnout have not been examined. This study was to explore the job stress × BDNF rs2049046 interaction and the role of serum BDNF level in job burnout in a Chinese Han population.

METHODS

Using a cross-sectional design, 205 healthy subjects were recruited from a public institution in Beijing and assessed for job stress using the House and Rizzo's Work Stress Scale, and job burnout using the Maslach Burnout Inventory (MBI). The BDNF rs2049046 polymorphism was genotyped and serum BDNF (sBDNF) levels were assayed in all of subjects.

RESULTS

The correlations between the job stress score and two burnout subscale scores (emotional exhaustion and cynicism) were significant (both p < 0.001), but not with professional efficacy. There were no significant main effects of the BDNF rs2049046 genotype on burnout, and no significant correlation was observed between sBDNF levels and job burnout. However, the interaction between the job stress and the BDNF rs2049046 genotype (F = 2.709, df = 2, 183, p = 0.032) or between the job stress and sBDNF levels on burnout was significant (t = -2.132, p = 0.035). To be specific, the individuals with the BDNF rs2049046 AT genotype showed a greater susceptibility to the burnout cynicism compared to AA homozygote only in medium-stress group (F = 4.327, df = 1,117, p = 0.015). The individuals who had lower sBDNF showed higher burnout level than those who had higher sBDNF in low-stress group.

CONCLUSIONS

Our findings suggest that the BDNF system may interact with job stress to affect burnout, showing that interaction between BDNF rs2049046 and job stress or the interaction between BDNF levels with work stress on certain burnout dimensions.

Chaiyu-Dixian Formula Exerts Protective Effects on Ovarian Follicular Abnormal Development in Chronic Unpredictable Mild Stress (CUMS) Rat Model

Background

Chronic stress has been known to impair the female reproductive function, but the mechanism remains to be further investigated. Chaiyu-Dixian Formula (CYDXF) has been reported to regulate human endocrine disorders clinically. However, whether this formula can affect chronic stress-induced ovarian follicular development is not clear.

Aim of the study

To examine effects of CYDXF on follicular development and explore possible mech anisms in a chronic unpredictable mild stress (CUMS) model.

Materials and Methods

Adult female rats were randomly divided into 5 groups control group, CUMS group (saline treatment), CUMS+Estradiol (E₂) (0.1 mg/kg) group, CUMS+CYDXF (2.73 g/kg) group, and CUMS+CYDXF (5.46 g/kg) group. Body weights and behavioral tests were documented. Serum hormone levels were determined by enzyme-linked immunosorbent assay (ELISA). Western blotting was used to detect the protein levels in the PI3K/Akt pathway and brain-derived neurotrophic factor (BDNF). The follicles were analyzed and classified according to their morphological characterization.

Results

CYDXF relieved depression-like behaviors and ameliorated the abnormality in rat estrous cycle within the rat model of CUMS. Moreover, CYDXF could regulate endocrine disorders, increase the proportion of antral follicles as well as decrease the proportion of follicular atresia, which suggested that CYDXF could alleviate abnormal follicular development and improve overall ovarian function. Furthermore, CYDXF also activated the BDNF-mediated PI3K/Akt signaling pathway.

Conclusions

CYDXF (at dose of both 2.73 and 5.46 g/kg) attenuated chronic stress-induced abnormal ovarian follicular development by relieving depression-like behaviors and improving ovarian function through partly the regulation of the BDNF-mediated PI3K/Akt pathway.

Association of the brain-derived neurotrophic factor Val66Met polymorphism with negative symptoms severity, but not cognitive function, in first-episode schizophrenia spectrum disorders

Objective

A functional polymorphism of the brain-derived neurotrophic factor gene (BDNF) Val66Met has been associated with cognitive function and symptom severity in patients with schizophrenia. It has been suggested that the Val66Met polymorphism has a role as a modulator in a range of clinical features of the illness, including symptoms severity, therapeutic responsiveness, age of onset, brain morphology and cognitive function. However, little work has been done in first-episode schizophrenia (FES) spectrum disorders. The objective of this study is to investigate the association of the BDNF Val66Met polymorphism on cognitive function and clinical symptomatology in FES patients.

Methods

Using a cross-sectional design in a cohort of 204 patients with FES or a schizophrenia spectrum disorder and 204 healthy matched controls, we performed BDNF Val66Met genotyping and tested its relationship with cognitive testing (attention, working memory, learning/verbal memory and reasoning/problem-solving) and assessment of clinical symptom severity.

Results

There was no significant influence of the BDNF allele frequency on cognitive factor scores in either patients or controls. An augmented severity of negative symptoms was found in FES patients that carried the Met allele.

Conclusions

The results of this study suggest that in patients with a first-episode of schizophrenia or a schizophrenia spectrum disorder, the BDNF Val66Met polymorphism does not exert an influence on cognitive functioning, but is associated with negative symptoms severity. BDNF may serve as suitable marker of negative symptomatology severity in FES patients within the schizophrenia spectrum.

Interactions between the combined genotypes of 5-HTTLPR and BDNF Val66Met polymorphisms and parenting on adolescent depressive symptoms: A three-year longitudinal study

BACKGROUND

The importance of multiple genes-environment interaction (G × E) has been highlighted in studies on depressive symptoms. 5-HTTLPR and BDNF Val66Met polymorphisms, with functional interconnection, have been implicated in the pathophysiology of depressive symptoms. However, little is understood about whether the interaction of 5-HTTLPR, BDNF Val66Met and parenting fits better with the epistatic or cumulative manner.

METHODS

865 adolescents (T1: M_age = 12.32, 50.2% girls) were included in a three-year interval longitudinal design. Standardized questionares about parenting and depressive symptoms were collected. Saliva samples were collected for genotyping.

RESULTS

Neither the concurrent nor longitudinal interaction of 5-HTTLPR, BDNF Val66Met and parenting (G × G × E) showed significant effects on depressive symptoms. The interaction between cumulative genotypes and positive parenting (CG × E) was significant, with the strong differential susceptibility model, for depressive symptoms concurrently but not longitudinally after statistical correction. Adolescents who carried 3 (i.e. SS and Val/Met, L allele and Val/Val) and 4 (i.e. SS and Val/Val), not 1 (i.e. L allele and Met/Met) or 2 cumulative susceptibility alleles (i.e. SS and Met/Met, L allele and Val/Met), reported fewer depressive symptoms if they had experienced higher levels of positive parenting, and more symptoms under lower levels of positive parenting.

LIMITATIONS

This study did not examine the 5-HTTLPR triallelic (rs25531) marker and did not include an external sample.

CONCLUSIONS

The combined effects of 5-HTTLPR and BDNF Val66Met polymorphisms functioned in a manner of cumulative rather than epistatic in response to positive parenting on early adolescent depressive symptoms.

The therapeutic potential of exercise for neuropsychiatric diseases: A review

Exercise is known to have a myriad of health benefits. There is much to be learned from the effects of exercise and its potential for prevention, attenuation and treatment of multiple neuropsychiatric diseases and behavioral disorders. Furthermore, recent data and research on exercise benefits with respect to major health crises, such as, that of opioid and general substance use disorders, make it very important to better understand and review the mechanisms of exercise and how it could be utilized for effective treatments or adjunct treatments for these diseases. In addition, mechanisms, epigenetics and sex differences are examined and discussed in terms of future research implications.

Effect of Zinc Supplementation on Physical and Psychological Symptoms, Biomarkers of Inflammation, Oxidative Stress, and Brain-Derived Neurotrophic Factor in Young Women with Premenstrual Syndrome: a Randomized, Double-Blind, Placebo-Controlled Trial

Zinc is known to have multiple beneficial effects including anti-inflammatory and antioxidant and anti-depressant actions. Data on the effects of zinc supplementation on biomarkers of inflammation, oxidative stress, and antidepressant-like effect among young women with premenstrual syndrome (PMS) are scarce. This study was a randomized, double-blind, placebo-controlled trial. Sixty women (18-30 years) with premenstrual syndrome diagnosed according to 30-item questionnaire were randomly assigned to receive either 30-mg zinc gluconate (group 1; n = 30) and/or placebo (group 2; n = 30) for 12 weeks. Premenstrual syndrome symptoms, total antioxidant capacity, high sensitivity reactive protein, and brain-derived neurotrophic factor were measured at study baseline and after 12-week intervention. After 12 weeks of intervention, PMS physical symptoms (P = 0.03) and psychological symptoms (P = 0.006) significantly decreased in zinc group compared to placebo group. We observed a significant increase in brain-derived neurotrophic factor (P = 0.01) and total antioxidant capacity (P ˂ 0.001) after 12 weeks of intervention with zinc compared to placebo. We failed to find any significant effect of zinc supplementation on high sensitivity reactive protein. Overall, zinc supplementation for 12 weeks among women with premenstrual syndrome had beneficial effects on physical and psychological symptoms of premenstrual syndrome, total antioxidant capacity, and brain-derived neurotrophic factor.

Brain Changes Induced by Electroconvulsive Therapy Are Broadly Distributed

BACKGROUND

Electroconvulsive therapy (ECT) is associated with volumetric enlargements of corticolimbic brain regions. However, the pattern of whole-brain structural alterations following ECT remains unresolved. Here, we examined the longitudinal effects of ECT on global and local variations in gray matter, white matter, and ventricle volumes in patients with major depressive disorder as well as predictors of ECT-related clinical response.

METHODS

Longitudinal magnetic resonance imaging and clinical data from the Global ECT-MRI Research Collaboration (GEMRIC) were used to investigate changes in white matter, gray matter, and ventricle volumes before and after ECT in 328 patients experiencing a major depressive episode. In addition, 95 nondepressed control subjects were scanned twice. We performed a mega-analysis of single subject data from 14 independent GEMRIC sites.

RESULTS

Volumetric increases occurred in 79 of 84 gray matter regions of interest. In total, the cortical volume increased by mean ± SD of 1.04 ± 1.03% (Cohen's d = 1.01, p < .001) and the subcortical gray matter volume increased by 1.47 ± 1.05% (d = 1.40, p < .001) in patients. The subcortical gray matter increase was negatively associated with total ventricle volume (Spearman's rank correlation ρ = -.44, p < .001), while total white matter volume remained unchanged (d = -0.05, p = .41). The changes were modulated by number of ECTs and mode of electrode placements. However, the gray matter volumetric enlargements were not associated with clinical outcome.

CONCLUSIONS

The findings suggest that ECT induces gray matter volumetric increases that are broadly distributed. However, gross volumetric increases of specific anatomically defined regions may not serve as feasible biomarkers of clinical response.

Brain-derived neurotrophic factor and schizophrenia

The brain-derived neurotrophic factor (BDNF) is a secretory growth factor that promotes neuronal proliferation and survival, synaptic plasticity and long-term potentiation in the central nervous system. Brain-derived neurotrophic factor biosynthesis and secretion are chrono-topically regulated processes at the cellular level, accounting for specific localizations and functions. Given its role in regulating brain development and activity, BDNF represents a potentially relevant gene for schizophrenia, and indeed BDNF and its non-synonymous functional variant, rs6265 (C → T, Val → Met) have been widely studied in psychiatric genetics. Human and animal studies have indicated that brain-derived neurotrophic factor is relevant for schizophrenia-related phenotypes, and that: (1) fine-tuned regulation of brain-derived neurotrophic factor secretion and activity is necessary to guarantee brain optimal development and functioning; (2) the Val → Met substitution is associated with impaired activity-dependent secretion of brain-derived neurotrophic factor; (3) disruption of brain-derived neurotrophic factor signaling is associated with altered synaptic plasticity and neurodevelopment. However, genome-wide association studies failed to associate the BDNF locus with schizophrenia, even though a sub-threshold association exists. Here, we will review studies focused on the relationship between the genetic variation of BDNF and schizophrenia, trying to fill the gap between genetic risk per se and insights from molecular biology. A deeper understanding of brain-derived neurotrophic factor biology and of the epigenetic regulation of brain-derived neurotrophic factor and its interactome during development may help clarifying the potential role of this gene in schizophrenia, thus informing development of brain-derived neurotrophic factor-based strategies of prevention and treatment of this disorder.

Uwhangchungsimwon, A Standardized Herbal Drug, Exerts an Anti-Depressive Effect in a Social Isolation Stress-Induced Mouse Model

Introduction

Uwhangchungsimwon (UCW) is one of the most representative standardized herbal drugs for the treatment of central nervous system diseases, including mood disorders, and has been used for over 600 years in Korea and China. In spite of the long clinical application of UCW, no experimental evidence for its use against depressive disorders exists. Here, we performed an animal study to investigate the anti-depressive effect of UCW and the underlying mechanisms.

Methods

A social isolation-induced depressive-like model was produced using C57BL/6J male mice by housing the mice individually for 31 days, and the mice underwent daily oral administration of distilled water, UCW (100, 200, 400 mg/kg) or fluoxetine (20 mg/kg) during the final 17 days. A tail suspension test (TST), forced swimming test (FST), and open field test (OFT) were used to explore the effects of UCW on depressive-like behaviors. 5-Hydroxytryptamine (5-HT) was measured in the dorsal raphe nuclei (DRN) using immunofluorescence. The serum corticosterone level was measured with its receptor and catecholamine, along with cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in the hippocampus.

Results

Social isolation stress effectively induced depressive-like behaviors, and UCW treatment significantly improved the symptoms of depressive-like behavior in the FST, TST, and OFT. The isolation stress-induced depletion of 5-HT was significantly ameliorated by UCW treatment. UCW also attenuated the activation of the glucocorticoid receptor (GR) and the elevated serum corticosterone level, as well as the hippocampal levels of dopamine and norepinephrine. Dexametasone-derived translocation of GR was inhibited by UCW treatment in PC12 cells and HT22 cells. In addition, alterations of tryptophan hydroxylase 2 (TPH2), BDNF, and CREB in the protein analyses were notably regulated by UCW treatment.

Conclusions

These results provide animal-based evidence for the anti-depressive effect of UCW, and its underlying mechanisms may involve regulating the serotonergic system, the hypothalamic-pituitary-adrenal (HPA) axis, and neurotrophin.

Topologically Guided Prioritization of Candidate Gene Transcripts Coexpressed with the 5-HT1A Receptor by Combining In Vivo PET and Allen Human Brain Atlas Data

The serotonin-1A receptor (5-HT_1AR) represents a viable target in the treatment of disorders of the brain. However, development of psychiatric drugs continues to be hindered by the relative inaccessibility of brain tissue. Although the efficacy of drugs selective for the 5-HT_1AR has not been proven, research continues to focus on drugs that influence this receptor subtype. To further knowledge on this topic, we investigated the topological coexpression patterns of the 5-HT_1AR. We calculated Spearman’s rho for the correlation of positron emission tomography-binding potentials (BP_ND) of the 5-HT_1AR assessed in 30 healthy subjects using the tracer [carbonyl-¹¹C]WAY-100635 and predicted whole-brain mRNA expression of 18 686 genes. After applying a threshold of r > 0.3 in a leave-one-out cross-validation of the prediction of mRNA expression, genes with ρ ≥ 0.7 were considered to be relevant. In cortical regions, 199 genes showed high correlation with the BP_ND of the 5-HT_1AR, in subcortical regions 194 genes. Using our approach, we could consolidate the role of BDNF and implicate new genes (AnxA8, NeuroD2) in serotonergic functioning. Despite its explorative nature, the analysis can be seen as a gene prioritization approach to reduce the number of genes potentially connected to 5-HT_1AR functioning and guide future in vitro studies.

Metabolite Profiling Revealed That a Gardening Activity Program Improves Cognitive Ability Correlated with BDNF Levels and Serotonin Metabolism in the Elderly

Metabolomics is useful for evaluating the fundamental mechanisms of improvements in the health functions of the elderly. Additionally, gardening intervention as a regular physical activity for the elderly maintained and improved physical, psychology, cognitive, and social health. This study was conducted to determine whether the cognitive ability of the elderly is affected by participating in a gardening activity program as a physical activity with a metabolomic potential biomarker. The gardening program was designed as a low to moderate intensity physical activity for the elderly. Serum metabolites resulting from gardening were subjected to metabolite profiling using gas chromatography time-of-flight mass spectrometry and ultra-high-performance liquid chromatography-linear trap quadruple-orbitrap-mass spectrometry followed by multivariate analyses. The partial least squares-discriminant analysis showed distinct clustering patterns among the control, non-gardening, and gardening groups. According to the pathway analysis, tryptophan metabolism including tryptophan, kynurenine, and serotonin showed significantly distinctive metabolites in the gardening group. Brain-derived neurotrophic factor levels (BDNF) in the gardening group were significantly increased after the gardening program. Correlation map analysis showed that the relative levels of tryptophan metabolites were positively correlated with BDNF. Our results show that tryptophan, kynurenine, and serotonin may be useful as metabolic biomarkers for improved cognitive ability by the gardening intervention.

Antidepressive Mechanisms of Probiotics and Their Therapeutic Potential

The accumulating knowledge of the host-microbiota interplay gives rise to the microbiota-gut-brain (MGB) axis. The MGB axis depicts the interkingdom communication between the gut microbiota and the brain. This communication process involves the endocrine, immune and neurotransmitters systems. Dysfunction of these systems, along with the presence of gut dysbiosis, have been detected among clinically depressed patients. This implicates the involvement of a maladaptive MGB axis in the pathophysiology of depression. Depression refers to symptoms that characterize major depressive disorder (MDD), a mood disorder with a disease burden that rivals that of heart diseases. The use of probiotics to treat depression has gained attention in recent years, as evidenced by increasing numbers of animal and human studies that have supported the antidepressive efficacy of probiotics. Physiological changes observed in these studies allow for the elucidation of probiotics antidepressive mechanisms, which ultimately aim to restore proper functioning of the MGB axis. However, the understanding of mechanisms does not yet complete the endeavor in applying probiotics to treat MDD. Other challenges remain which include the heterogeneous nature of both the gut microbiota composition and depressive symptoms in the clinical setting. Nevertheless, probiotics offer some advantages over standard pharmaceutical antidepressants, in terms of residual symptoms, side effects and stigma involved. This review outlines antidepressive mechanisms of probiotics based on the currently available literature and discusses therapeutic potentials of probiotics for depression.

The potential therapeutic effects of the gut microbiome manipulation by synbiotic containing-Lactobacillus plantarum on neuropsychological performance of diabetic rats

BACKGROUND

The manipulation of gut microbiota as a target has been suggested to reduce the risks for a number of diseases such as type 2 diabetes mellitus (T2DM). Conversely, T2DM is associated with complications such as gut and brain disorders. Furthermore, the impact of probiotics and prebiotics to improve T2DM complications are reported. Thus, the present study seeks to investigate the therapeutic and neuropsychological effects of L. plantarum and inulin in diabetic rats.

METHODS

Throughout the investigation, L. plantarum, inulin or their combination (synbiotic) was administered to diabetic rats. in the end, fecal samples were collected to evaluate the gut microbial composition. Then behavioral tests were conducted. Subsequently, the obtainment of the prefrontal cortex (PFC) and hippocampal samples.

RESULTS

Our data demonstrated that administration of L. plantarum and inulin could improve gut dysbiosis and oxidative stress status. In addition, it could ameliorate serotonin and BDNF/TrkB signaling pathway. Notably, a strong correlation between the gut microbiota changes and cognition responses was observed. Interestingly, synbiotics intake exploited a rather powerful effect on oxidative stress markers.

CONCLUSION

The findings confirm that there is a beneficial therapeutic potential of supplements, especially symbiotic. Moreover, neuropsychological improvement associated with balanced gut microbiome.

Stress and the gut microbiota-brain axis

Stress is a nonspecific response of the body to any demand imposed upon it, disrupting the body homoeostasis and manifested with symptoms such as anxiety, depression or even headache. These responses are quite frequent in the present competitive world. The aim of this review is to explore the effect of stress on gut microbiota. First, we summarize evidence of where the microbiota composition has changed as a response to a stressful situation, and thereby the effect of the stress response. Likewise, we review different interventions that can modulate microbiota and could modulate the stress according to the underlying mechanisms whereby the gut-brain axis influences stress. Finally, we review both preclinical and clinical studies that provide evidence of the effect of gut modulation on stress. In conclusion, the influence of stress on gut microbiota and gut microbiota on stress modulation is clear for different stressors, but although the preclinical evidence is so extensive, the clinical evidence is more limited. A better understanding of the mechanism underlying stress modulation through the microbiota may open new avenues for the design of therapeutics that could boost the pursued clinical benefits. These new designs should not only focus on stress but also on stress-related disorders such as anxiety and depression, in both healthy individuals and different populations.

Probiotics, prebiotics, and synbiotics for the treatment of dementia: Protocol for a systematic review

BACKGROUND

The number of dementia patients in the world is large, and the number of dementia patients will continue to rise in the future, which will bring a heavy social and economic burden. No interventions have been found to cure dementia. Medication can delay the progression of the disease and impose an economic burden. Some non-drug therapies often require the care of the caregiver. Probiotics, prebiotics, and synbiotics may intervene in dementia through microbiota-gut-brain axis (MGBA). However, their effectiveness and safety are still obscure and deserve further investigation. The purpose of this study is to assess the effect and safety of probiotics, prebiotics, and synbiotics in treating dementia.

METHODS

We will summarize and meta-analyze randomized controlled trials (RCTs) of probiotics, prebiotics, and synbiotics for the treatment of dementia. RCTs comparing probiotics, prebiotics, and synbiotics with blank control, placebo or conventional therapies will be included. RCTs comparing probiotics, prebiotics, and synbiotics plus conventional therapies with conventional therapies alone will also be included. The following electronic databases will be searched: PubMed, Cochrane Library, EMBASE, CNKI, CBM, VIP, and WAN FANG DATA. The methodological quality of RCTs will be assessed using the Cochrane risk assessment tool. All trials included will be analyzed according to the criteria of the Cochrane Handbook. Review Manager 5.3, R-3.5.1 software will be used for publication bias analysis. Grading of Recommendations Assessment, Development and Evaluation (GRADE) pro-GDT web solution will be used for evidence evaluation.

RESULTS

This review will evaluate the effects of probiotics, prebiotics, and synbiotics on cognitive function, behavioral and psychological symptoms of dementia, quality of life (QOL), functional performance in activities of daily living, and compliance with the intervention and safety in patients with dementia.

CONCLUSIONS

This review will provide clear evidence to assess the effectiveness and safety of probiotics, prebiotics, and synbiotics for dementia.OSF registration number: DOI 10.17605/OSF.IO/2Q3AK.

AP-1 controls the p11-dependent antidepressant response

Selective serotonin reuptake inhibitors (SSRIs) are the most widely prescribed drugs for mood disorders. While the mechanism of SSRI action is still unknown, SSRIs are thought to exert therapeutic effects by elevating extracellular serotonin levels in the brain, and remodel the structural and functional alterations dysregulated during depression. To determine their precise mode of action, we tested whether such neuroadaptive processes are modulated by regulation of specific gene expression programs. Here we identify a transcriptional program regulated by activator protein-1 (AP-1) complex, formed by c-Fos and c-Jun that is selectively activated prior to the onset of the chronic SSRI response. The AP-1 transcriptional program modulates the expression of key neuronal remodeling genes, including S100a10 (p11), linking neuronal plasticity to the antidepressant response. We find that AP-1 function is required for the antidepressant effect in vivo. Furthermore, we demonstrate how neurochemical pathways of BDNF and FGF2, through the MAPK, PI3K, and JNK cascades, regulate AP-1 function to mediate the beneficial effects of the antidepressant response. Here we put forth a sequential molecular network to track the antidepressant response and provide a new avenue that could be used to accelerate or potentiate antidepressant responses by triggering neuroplasticity.

Dietary Fatty Acids and Microbiota-Brain Communication in Neuropsychiatric Diseases

The gut-brain axis is a multimodal communication system along which immune, metabolic, autonomic, endocrine and enteric nervous signals can shape host physiology and determine liability, development and progression of a vast number of human diseases. Here, we broadly discussed the current knowledge about the either beneficial or deleterious impact of dietary fatty acids on microbiota-brain communication (MBC), and the multiple mechanisms by which different types of lipids can modify gut microbial ecosystem and contribute to the pathophysiology of major neuropsychiatric diseases (NPDs), such as schizophrenia (SCZ), depression and autism spectrum disorders (ASD).

Escalating low-dose Δ9 -tetrahydrocannabinol exposure during adolescence induces differential behavioral and neurochemical effects in male and female adult rats

Cannabinoid administration during adolescence affects various physiological processes, such as motor and affective response, cognitive-related functions and modulates neurotransmitter activity. Literature remains scant concerning the parallel examination of the effects of adolescent escalating low-dose Δ⁹ -tetrahydrocannabinol (Δ⁹ -THC) on the behavioral and plasticity profile of adult rats in both sexes. Herein, we investigated the long-term behavioral, neurochemical and neurobiological effects of adolescent escalating low Δ⁹ -THC doses in adult male and female rats. In adult males, adolescent low-dose Δ⁹ -THC exposure led to increased spontaneous locomotor activity, impaired behavioral motor habituation and defective short-term spatial memory, paralleled with decreased BDNF protein levels in the prefrontal cortex. In this brain area, serotonergic activity was increased, as depicted by the increased serotonin turnover rate, while the opposite effect was observed in the hippocampus, a region where SERT levels were enhanced by Δ⁹ -THC, compared with vehicle. In adult females, adolescent Δ⁹ -THC treatment led to decreased spontaneous vertical activity and impaired short-term spatial memory, accompanied by increased BDNF protein levels in the prefrontal cortex. Present findings emphasize the key role of adolescent escalating low Δ⁹ -THC exposure in the long-term regulation of motor response, spatial-related cognitive functions and neuroplasticity indices in adulthood. In this framework, these changes could, at a translational level, contribute to clinical issues suggesting the development of psychopathology in a sex-differentiated manner following Δ⁹ -THC exposure during adolescence.

Novel BDNF-regulatory microRNAs in neurodegenerative disorders pathogenesis: An in silico study

Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor with various roles in the central nervous system neurogenesis, neuroprotection, and axonal guide. By attaching to Tropomyosin receptor kinase B (TrkB) receptor, this protein triggers downstream signaling pathways which lead to cellular growth, proliferation, survival, and neuroplasticity. Deregulation at mRNA level is involved in various central nervous system disorders including, Huntington, Alzheimer's, Multiple Sclerosis, and Amyotrophic Lateral Sclerosis diseases. Considering the importance of BDNF functions, deciphering the regulatory mechanisms controlling BDNF expression level could pave the way to develop more accurate and efficient treatments for neurological diseases. Among different regulatory systems, microRNAs (miRNAs) play prominent roles by targeting genes 3' untranslated regions. In this study, 127 validated and bioinformatic-predicted miRNAs with potentially regulatory roles in BDNF expression were analyzed. Various aspects of miRNAsö possible functions were assessed by bioinformatic online tools to find their potential regulatory functions in signaling pathways, neurological disorders, expression of transcription factors and miRNAs sponge. Analyzed data led to introduce 5 newly reported miRNAs that could regulate BDNF expression level. Finally, high throughput sequencing data from different brain regions and neurological disorders were analyzed to measure correlation of candidate miRNAs with BDNF level in experimental studies. In this study, a list of novel miRNAs with possible regulatory roles in BDNF expression level involving in different neurological disorders was introduced.

Antidepressant-like effect induced by P2X7 receptor blockade in FSL rats is associated with BDNF signalling activation

BACKGROUND

P2X7 receptors (P2X7R) are ligand-gated ion channels activated by adenosine 5'-triphosphate (ATP), which are involved in processes that are dysfunctional in stress response and depression, such as neurotransmitter release, and neuroimmune response. Genetic and pharmacological inhibition of the P2X7R induce antidepressant-like effects in animals exposed to stress. However, the effect of P2X7R antagonism in an animal model of depression based on selective breeding has not previously been studied, and the mechanism underling the antidepressant-like effect induced by the P2X7R blockade remains unknown.

AIMS

The present study aimed to: (1) determine whether P2X7R blockade induces antidepressant-like effects in the Flinders Sensitive Line (FSL) rats and, (2) investigate whether brain-derived neurotrophic factor (BDNF) signalling in the frontal cortex and hippocampus is involved in this effect.

METHODS

FSL and the control Flinders Resistant Line (FRL) rats were treated with vehicle or the P2X7R antagonist A-804598 (3, 10 or 30 mg/Kg/day) for 1 or 7 days before being exposed to the forced swim test (FST). After the behavioural test, animals were decapitated, their brains were removed and the frontal cortex, ventral and dorsal hippocampus were dissected for BDNF signalling analysis.

RESULTS

We found that repeated treatment with A-804598 (30 mg/Kg) reduced the immobility time in the FST and activated the BDNF signalling in the ventral hippocampus of FSL rats.

CONCLUSIONS

P2X7R blockade induces an antidepressant-like effect associated with increased levels of BDNF-AKT-p70 S6 kinase in the ventral hippocampus, which may be mediated by tropomyosin-related kinase B (TRKB) receptor activation supporting the notion of P2X7R antagonism as a potential new antidepressant strategy.

Obsessive-compulsive disorder and growth factors: A comparative review

The goal of this article is to clarify the role of various growth factors in the establishment and progression of obsessive-compulsive disorder (OCD). OCD is a chronic mental disorder with recurrent intrusive thoughts and/or repetitive compulsive behaviors that increase during stressful periods. Growth and neurotrophic factors may be contributing factors in the pathophysiology of OCD. Many of them are synthesized and released within the central nervous system and act as trophic agents in neurons; some of them are involved in brain growth, development, neurogenesis, myelination and plasticity, while others take part in the protection of the nervous system following brain injuries. This paper attempts to identify all articles investigating the relationship between OCD and neurotrophic and growth factors, in both animal and human studies, with a focus on adult brain studies. Based on the PubMed and Scopus and Science Direct search tools, the available articles and studies are reviewed. Out of 230 records in total, the ones related to our review topic were taken into account to further understand the pathophysiological mechanism(s) of OCD, providing methods to improve its symptoms via the modification of neurotrophins and growth factor imbalances.