Brain-Derived Neurotrophic Factor, Depression, and Physical Activity: Making the Neuroplastic Connection

Dual pharmacological inhibitor of endocannabinoid degrading enzymes reduces depressive-like behavior in female rats

Major depressive disorder (MDD) is common, often under-treated and a leading cause of disability and mortality worldwide. The causes of MDD remain unclear, including the role of the endocannabinoid system. Intriguingly, the prevalence of depression is significantly greater in women than men. In this study we examined the role of endocannabinoids in depressive behavior. The levels of endocannabinoids, N-arachidonoyl ethanolamide (AEA) and 2-arachidonoyl glycerol (2-AG) were measured along with brain derived neurotrophic factor (BDNF) in postmortem ventral striata of female patients with MDD and non-psychiatric controls, and in Wistar Kyoto (WKY) rat, a selectively inbred strain of rat widely used for testing the depressive behavior. The effect of pharmacological elevation of endocannabinoids through inhibition of their catabolizing enzymes (fatty acid amide hydrolase [FAAH] and monoacyl glycerol lipase [MAGL]) on depressive-like phenotype was also assessed in WKY rat. The findings showed lower levels of endocannabinoids and BDNF in the ventral striata of MDD patients and WKY rats. A dual inhibitor of FAAH and MAGL, JZL195, elevated the endocannabinoids and BDNF levels in ventral striatum, and reduced the depressive-like phenotype in female WKY rats. Collectively, our study suggests a blunted ventral striatal endocannabinoid and BDNF signaling in depressive behavior and concludes that endocannabinoid enhancing agents may have an antidepressant effect.

Serum Levels of FGF21, β-Klotho, and BDNF in Stable Coronary Artery Disease Patients With Depressive Symptoms: A Cross-Sectional Single-Center Study

Background: The incidence of depressive symptoms (DS) in patients with stable coronary artery disease (SCAD) is significantly higher than those in healthy population, and that DS are independent risk factors for cardiovascular events. Previous studies have reported that fibroblast growth factor 21 (FGF21), β-klotho, mature brain-derived neurotrophic factor (mBDNF), and BDNF precursor (proBDNF) play important roles in the pathogenesis and treatment of coronary heart disease and depression. With this in mind, the present study aimed to clarify the relationship between FGF21, β-klotho, mBDNF, and proBDNF and SCAD with comorbid depression, in addition to also exploring the underlying mechanisms of these disease processes. Methods: A total of 116 patients with SCAD and 45 healthy controls were recruited. Patients with SCAD were further divided into two subgroups based on the Zung Self-Rating Depression Scale (SDS), which were characterized as those with no DS (NDS) and those with DS. Baseline data were collected, and serum levels of FGF21, β-klotho, mBDNF, and proBDNF were determined. Results: In SCAD patients, Gensini scores-denoting the degree of coronary arteriostenosis-were significantly greater in the DS group than in the NDS group. There was also a positive correlation between the Gensini scores and the SDS scores. Patients in the SCAD group demonstrated a lower serum FGF21. Serum β-klotho, mBDNF, and mBDNF/proBDNF were also significantly lower in the DS group than in the NDS group. Furthermore, β-klotho and mBDNF were negatively correlated with the SDS scores. Additionally, SCAD patients were divided into lower- and higher-level groups using hierarchical cluster analysis, with the results highlighting that patients in the lower mBDNF group had a higher incidence of DS. Conclusions: The depression score was positively correlated with the severity of coronary artery stenosis, and serum FGF21, β-klotho, mBDNF, and proBDNF were closely related to the development of DS in patients with SCAD. These observations suggest FGF21, β-klotho, mBDNF, and proBDNF as potential diagnostic and/or therapeutic targets for SCAD with co-morbid depression.

The Effects of Individual Psychotherapy in BDNF Levels of Patients With Mental Disorders: A Systematic Review

BACKGROUND

Brain-derived Neurotrophic Factor (BDNF) is considered the main cerebral neurotrophin and is produced in the central neural system and peripherals. Its levels are reduced in patients with several psychiatric disorders, but it is unclear if the response to psychotherapy can alter its concentration.

OBJECTIVE

To carry out a systematic review evaluating the effects of individual psychotherapy in BDNF levels in patients with mental disorders.

METHODS

The databases PubMed, EMBASE, PsycArticles, SciELO, Web of Science, and CENTRAL; the last search was performed on October 2019 for trials evaluating the effects of individual psychotherapy in BDNF levels in adults with mental disorders. PROSPERO registration: CRD42018108144.

RESULTS

Eight of 293 studies were included. A rise in BDNF levels was observed in depressive patients when psychotherapy was combined with medication. Patients with post-traumatic stress disorder (PTSD) who responded to therapy presented a raise in BDNF levels mostly when combined with physical activity. There was a rise in BDNF levels in those who responded to psychotherapy in patients with bulimia, in borderline patients, and in insomniacs.

CONCLUSIONS

The BDNF seems to present variations after psychotherapy especially in patients with bulimia, PTSD, insomnia, and borderline. These subjects also have symptom reduction. Thereby, BDNF could be a supplemental tool to analyze the success to psychotherapy. BDNF levels in patients with major depression after therapy are still controversial and the short follow-up of most studies is a limiting factor.

Fast-Acting Black-Phosphorus-Assisted Depression Therapy with Low Toxicity

A black phosphorus (BP)-nanosheet-based drug-delivery system containing a therapeutic drug (Fluoxetine, Flu) is synthesized. According to subsequent behavioral, biochemical, and electrophysiological analysis, BP-Flu, after irradiated with near-infrared light (808 nm), can significantly reduce the therapy time of depression. Meanwhile, the inherent biotoxicity of Flu is also alleviated.

Effect of black chokeberry on skeletal muscle damage and neuronal cell death

[Purpose]

Numerous epidemiological studies have shown that it is possible to prescribe exercise for neurodegenerative disease, such as Alzheimer's disease and Parkinson’s disease. However, despite the availability of diverse scientific knowledge, the effects of exercise in this regard are still unclear. Therefore, this study attempted to investigate a substance, such as black chokeberry (Aronia melanocapa L.) that could improve the ability of the treatment and enhance the benefits of exercising in neurodegenerative diseases.

[Methods]

The cell viability was tested with 2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolim-5-carboxanilide and the cells were stained with ethidium homodimer-1 solution. The mRNA expression levels were evaluated by microarray. The active compounds of black chokeberry ethanolic extract (BCE) were analyzed by gas chromatography. The chemical shift analysis in the brain was performed using magnetic resonance spectroscopy.

[Results]

BCE treatment decreased hydrogen peroxide-induced L6 cell death and beta amyloid induced primary neuronal cell death. Furthermore, BCE treatment significantly reduced the mRNA levels of the inflammatory factors, such as IL-1α, Cxcl13, IL36rn, Itgb2, Epha2, Slamf8, Itgb6, Kdm6b, Acvr1, Cd6, Adora3, Cd27, Gata3, Tnfrsf25, Cd40lg, Clec10a, and Slc11a1, in the primary neuronal cells. Next, we identified 16 active compounds from BCE, including D-mannitol. In vivo, BCE (administered orally at a dosage of 50 mg/kg) significantly regulated chemical shift in the brain.

[Conclusion]

Our findings suggest that BCE can serve as a candidate for neurodegenerative disease therapy owing to its cyto-protective and anti-inflammatory effects. Therefore, BCE treatment is expected to prevent damage to the muscles and neurons of the athletes who continue high intensity exercise. In future studies, it would be necessary to elucidate the effects of combined BCE intake and exercise.

Kleeb Bua Daeng, a Thai Traditional Herbal Formula, Ameliorated Unpredictable Chronic Mild Stress-Induced Cognitive Impairment in ICR Mice

Thai traditional herbal formula ''Kleeb Bua Daeng (KBD)''consists of a 1:1:1 ratio (dry weight) of three medicinal plants: Piper nigrum fruit, the aerial part of Centella asiatica and the petals of Nelumbo nucifera. Oral administration of KBD to unpredictable chronic mild stress (UCMS) mice significantly improved their cognitive function caused by chronic mild stress. Daily administration of KBD significantly decreased the serum corticosterone (CORT) and malondialdehyde (MDA) levels but increased the catalase and superoxide dismutase activities in both frontal cortex and hippocampus. The effects of KBD were similar to those caused by oral administration of vitamin E. HPLC analysis of the KBD extract revealed the presence of piperine, madecassoside, asiaticoside, luteolin-7-O-glucoside, rutin, kaempferol-3-glucoside, quercetin, kaempferol and ferulic acid as major constituents.

Association between ideal cardiovascular health and depression incidence: a longitudinal analysis of ELSA-Brasil

OBJECTIVE

We investigated whether ideal cardiovascular health (ICH), a metric proposed by the American Heart Association, predicts depression development.

METHODS

Cohort analysis from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Adults with no current depression and other common mental disorders, cardiovascular diseases, and antidepressant drug use at baseline had their ICH (composite score of smoking, dietary habits, body mass index, blood pressure, fasting glucose, cholesterol, and physical activity) assessed and classified into poor, intermediate, and optimal. Depression was assessed using the Clinical Interview Schedule-Revised (CIS-R). Poisson regression models, adjusted for sociodemographic factors and alcohol consumption, were employed. Stratified analyses were performed for age and sex.

RESULTS

We included 9214 participants (mean age 52 ± 9 years, 48.6% women). Overall depression incidence at 3.8-year follow-up was 1.5%. Intermediate and poor ICH significantly increased the risk rate (RR) of developing depression (2.48 [95%CI 1.06-5.78] and 3 [1.28-7.03], respectively) at a 3.8-year follow-up. Higher ICH scores decreased the rate of depression development (RR = 0.84 [0.73-0.96] per metric). Stratified analyses were significant for women and adults < 55 years old.

CONCLUSIONS

Poor cardiovascular health tripled depression risk at follow-up in otherwise healthy adults. Ameliorating cardiovascular health might decrease depression risk development.

Modelling resilience in adolescence and adversity: a novel framework to inform research and practice

Recent conceptualisations of resilience have advanced the notion that it is a dynamic and multifaceted construct. However, its adaptive components, especially those forged by adversity, have not been fully realised, and its neurobiological and psychosocial underpinnings are yet to be meaningfully integrated. In part, this is because a developmental perspective is often neglected in the formulation of resilience. In this review, we consider the findings of resilience research, with a specific emphasis on the developmental period of adolescence. To bridge the gaps in our current understanding, we propose a model of resilience that is predicated on experiencing adversity. Specifically, our model provides a sophisticated insight into the components of resilience, which, together with intrinsic features, involves facilitation of, and skill acquisition via strengthening processes we term tempering and fortification. The model also points to the potential trajectories of adversity-driven resilience and forms the basis of a framework that allows for individual variance in resilience, and the identification of both neurobiological and psychosocial targets for prevention and therapeutic interventions.

Long distance ski racing is associated with lower long-term incidence of depression in a population based, large-scale study

Physical activity has been proposed to be beneficial for prevention of depression, although the importance of exercise intensity, sex-specific mechanisms, and duration of the effects need to be clarified. Using an observational study design, following 395,369 individuals up to 21 years we studied whether participation in an ultralong-distance cross-country ski race was associated with lower risk of developing depression. Skiers (participants in the race) and matched non-skiers from the general population (non-participants in the race) were studied after participation (same year for non-participation) in the race using the Swedish population and patient registries. The risk of depression in skiers (n = 197,685, median age 36 years, 38% women) was significantly lower, to nearly half of that in non-skiers (adjusted hazard ratio, HR 0.53) over the follow-up period. Further, a higher fitness level (measured as the finishing time to complete the race, a proxy for higher exercise dose) was associated with lower incidence of depression in men (adjusted HR 0.65), but not in women. Our results support the recommendations of engaging in physical activity as a preventive strategy decreasing the risk for depression in both men and women. Furthermore, the exercise could reduce risk for depression in a dose-dependent matter, in particular in males.

[Exercise for depression treatment. Physiological mechanisms]

This literature review considers meta-analyzes, systematic reviews and original research over the last decade addressing a comprehensive analysis of the antidepressant effect of targeted physical exercise and physical activity in general. Exercise is a promising non-pharmacological treatment for depression, showing effects that are comparable or may even exceed other first-line treatments of depression. The article introduces modern ideas about the mechanisms of depression and mechanisms of exercise effects on depression manifestations. The structures of the central nervous system, changing with the effective exercise-based treatment of depression, are indicated. Physical activity stimulates the secretion of growth factors, maintenance of angio-, synapto-, and neurogenesis. The regulation of antioxidant protection of neuronal mitochondria, a decrease in pro-inflammatory reactions and stress reactivity are also observed in response to regular exercise. Physical activity has a multimodal effect that stimulates biochemical pathways and restores neuronal structures disturbed in depression.

Affective biases and their interaction with other reward-related deficits in rodent models of psychiatric disorders

Major depressive disorder (MDD) is one of the leading global causes of disability. Symptoms of MDD can vary person to person, and current treatments often fail to alleviate the poor quality of life that patients experience. One of the two core diagnostic criteria for MDD is the loss of interest in previously pleasurable activities, which suggests a link between the disease aetiology and reward processing. Cognitive impairments are also common in patients with MDD, and more recently, emotional processing deficits known as affective biases have been recognised as a key feature of the disorder. Studies in animals have found similar affective biases related to reward. In this review we consider these affective biases in the context of other reward-related deficits and examine how affective biases associated with learning and memory may interact with the wider behavioural symptoms seen in MDD. We discuss recent developments in how analogues of affective biases and other aspects of reward processing can be assessed in rodents, as well as how these behaviours are influenced in models of MDD. We subsequently discuss evidence for the neurobiological mechanisms contributing to one or more reward-related deficits in preclinical models of MDD, identified using these behavioural assays. We consider how the relationships between these selective behavioural assays and the neurobiological mechanisms for affective bias and reward processing could be used to identify potential treatment strategies.

Physical Activity and the Occurrence of Postnatal Depression-A Systematic Review

Background and Objectives: During pregnancy and the postnatal period many changes occur in a woman's body, both in mental and physical spheres. The birth of a child and a new role-of a mother-can sometimes be associated with numerous negative emotions, uncertainty, fear, anxiety, disgust, depression, or sadness. In the puerperium period, the development of baby blues or postpartum depression may occur. Postpartum depression develops within one month of childbirth and may last up to one year. Depressive disorders that may develop in a young mother affect both her and the newborn's health. That is why it is so important to try to search for factors that could significantly reduce the likelihood of developing depression in this period. The study aims at assessing the relationship between physical activity during pregnancy and puerperium or in the postpartum and the development of postnatal depression. Materials and Methods: A review of the literature was carried out in the Medline-PubMed database. The search terms were "pregnancy" AND "physical activity AND postpartum depression". The study included only English-language publications published in the period 2000-2018. Results: A total of 216 references were found. After establishing the inclusion and exclusion criteria based on the analysis of titles and abstracts, 173 articles were excluded from the review. A total of 43 publications were read in full. Finally, 16 articles were included in the review. It was shown that regular physical activity during pregnancy, pregnancy, and puerperium, or in the postnatal period itself as compared to inactivity, reduces the risk of developing depression in pregnant women and after the birth of a child. Conclusions: Physical activity can be an essential factor in the prevention of depressive disorders of women in the postnatal period.

Current understanding of bipolar disorder: Toward integration of biological basis and treatment strategies

Biological studies of bipolar disorder initially focused on the mechanism of action for antidepressants and antipsychotic drugs, and the roles of monoamines (e.g., serotonin, dopamine) have been extensively studied. Thereafter, based on the mechanism of action of lithium, intracellular signal transduction systems, including inositol metabolism and intracellular calcium signaling, have drawn attention. Involvement of intracellular calcium signaling has been supported by genetics and cellular studies. Elucidation of the neural circuits affected by calcium signaling abnormalities is critical, and our previous study suggested a role of the paraventricular thalamic nucleus. The genetic vulnerability of mitochondria causes calcium dysregulation and results in the hyperexcitability of serotonergic neurons, which are suggested to be susceptible to oxidative stress. Efficacy of anticonvulsants, animal studies of candidate genes, and studies using induced pluripotent stem cell-derived neurons have suggested a relation between bipolar disorder and the hyperexcitability of neurons. Recent genetic findings suggest the roles of polyunsaturated acids. At the systems level, social rhythm therapy targets circadian rhythm abnormalities, and cognitive behavioral therapy may target emotion/cognition (E/C) imbalance. In the future, pharmacological and psychosocial treatments may be combined and optimized based on the biological basis of each patient, which will realize individualized treatment.

Integrated identification of key genes and pathways in Alzheimer's disease via comprehensive bioinformatical analyses

Background

Alzheimer's disease (AD) is known to be caused by multiple factors, meanwhile the pathogenic mechanism and development of AD associate closely with genetic factors. Existing understanding of the molecular mechanisms underlying AD remains incomplete.

Methods

Gene expression data (GSE48350) derived from post-modern brain was extracted from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were derived from hippocampus and entorhinal cortex regions between AD patients and healthy controls and detected via Morpheus. Functional enrichment analyses, including Gene Ontology (GO) and pathway analyses of DEGs, were performed via Cytoscape and followed by the construction of protein-protein interaction (PPI) network. Hub proteins were screened using the criteria: nodes degree≥10 (for hippocampus tissues) and ≥ 8 (for entorhinal cortex tissues). Molecular Complex Detection (MCODE) was used to filtrate the important clusters. University of California Santa Cruz (UCSC) and the database of RNA-binding protein specificities (RBPDB) were employed to identify the RNA-binding proteins of the long non-coding RNA (lncRNA).

Results

251 & 74 genes were identified as DEGs, which consisted of 56 & 16 up-regulated genes and 195 & 58 down-regulated genes in hippocampus and entorhinal cortex, respectively. Biological analyses demonstrated that the biological processes and pathways related to memory, transmembrane transport, synaptic transmission, neuron survival, drug metabolism, ion homeostasis and signal transduction were enriched in these genes. 11 genes were identified as hub genes in hippocampus and entorhinal cortex, and 3 hub genes were identified as the novel candidates involved in the pathology of AD. Furthermore, 3 lncRNAs were filtrated, whose binding proteins were closely associated with AD.

Conclusions

Through GO enrichment analyses, pathway analyses and PPI analyses, we showed a comprehensive interpretation of the pathogenesis of AD at a systematic biology level, and 3 novel candidate genes and 3 lncRNAs were identified as novel and potential candidates participating in the pathology of AD. The results of this study could supply integrated insights for understanding the pathogenic mechanism underlying AD and potential novel therapeutic targets.

Physical Exercise Increased Brain-Derived Neurotrophic Factor in Elderly Population with Depression

BACKGROUND

Depression is very common in the elderly population. Physical exercise is one of the non-pharmacological procedures that promise to be a solution to improve the severity of depression. Brain-Derived Neurotrophic Factor (BDNF) plays a role in maintaining the survival of neuronal cells and in the regulation of synapse plasticity, affecting serotonin production in the hippocampus and thus the depressive symptoms.

AIM

This study aimed to assess the role of physical exercise in affecting BDNF levels in elderly with depression.

METHODS

Thirty-five elderly women (age ≥ 50 years) with depressive episodes based on Diagnostic and Statistical Manual of Mental Disorders (DSM)-V criteria were enrolled as treatment group, and 35 elderly women without depressive episodes were enrolled as control group, and underwent physical exercise in the form of treadmill with a speed of 6 km/h for 15 minutes. Physical exercise was carried out once a day for 28 days. As much as 1 ml of blood from the study, subjects were obtained from the cubital vein before the exercise commenced. Brain-Derived Neurotrophic Factor (BDNF) serum level was assessed by Enzyme-Linked Immunosorbent Assay (ELISA). Data were presented in the form of mean ± SD. An independent T-test was used to test levels after exercise in the depression group compared to the non-depression group.

RESULTS

Pre-exercise BDNF levels in the depression group were lower than the group of elderly without depression. Physical exercise increased BDNF production in both elderly groups with and without depression. In the depression group, the increasing percentage of BDNF level was higher compared to non-depressive elderly.

CONCLUSION

The increasing percentage of BDNF level was found to be higher in depressive elderly performing physical exercise. Physical exercise may be beneficial in supporting the therapy of elderly with depression.

Antidepressant-like activity of hyperforin and changes in BDNF and zinc levels in mice exposed to chronic unpredictable mild stress

Chronic unpredictable mild stress (CUMS) - a rodent model of depression mimics a variety of neurochemical and behavioral alterations similar to those seen in human depression. This study evaluated the antidepressant activity of hyperforin in the CUMS model using fluoxetine (FLX) as a reference drug. The antidepressant-like effects of hyperforin and FLX were evaluated in the tail suspension test (TST), forced swim test (FST), and splash test (SPT). CUMS induced an increase in immobility time in mice (pro-depressive effects) in the FST and TST. CUMS-induced changes were reversed by chronic treatment with hyperforin (2.5 and 5 mg/kg), as well as FLX (10 mg/kg). SPT results revealed a decrease in the frequency and duration of grooming in stressed mice. These effects were normalized by hyperforin (5 mg/kg) and FLX treatment. Hyperforin (2.5 mg/kg) only reversed the CUMS-induced deficits related to the frequency of grooming. CUMS also caused a decrease in zinc concentration in the frontal cortex (FC) and hippocampus (Hp) of mice; hyperforin (2.5 mg/kg) increased zinc concentration in the Hp of control rats. CUMS also induced a decrease in BDNF protein levels in the FC and Hp, while decreasing the pCREB/CREB ratio only in the Hp. Hyperforin (2.5 and 5 mg/kg) reversed the CUMS-induced reduction of BDNF only in the Hp. Our results demonstrate the antidepressant-like activity of hyperforin in the CUMS model in mice and the possible involvement of hippocampal BDNF/zinc alterations in this activity.

Modulation of Serum Brain-Derived Neurotrophic Factor by a Single Dose of Ayahuasca: Observation From a Randomized Controlled Trial

Serotonergic psychedelics are emerging as potential antidepressant therapeutic tools, as suggested in a recent randomized controlled trial with ayahuasca for treatment-resistant depression. Preclinical and clinical studies have suggested that serum brain-derived neurotrophic factor (BDNF) levels increase after treatment with serotoninergic antidepressants, but the exact role of BDNF as a biomarker for diagnostic and treatment of major depression is still poorly understood. Here we investigated serum BDNF levels in healthy controls (N = 45) and patients with treatment-resistant depression (N = 28) before (baseline) and 48 h after (D2) a single dose of ayahuasca or placebo. In our sample, baseline serum BDNF levels did not predict major depression and the clinical characteristics of the patients did not predict their BDNF levels. However, at baseline, serum cortisol was a predictor of serum BDNF levels, where lower levels of serum BDNF were detected in a subgroup of subjects with hypocortisolemia. Moreover, at baseline we found a negative correlation between BDNF and serum cortisol in volunteers with eucortisolemia. After treatment (D2) we observed higher BDNF levels in both patients and controls that ingested ayahuasca (N = 35) when compared to placebo (N = 34). Furthermore, at D2 just patients treated with ayahuasca (N = 14), and not with placebo (N = 14), presented a significant negative correlation between serum BDNF levels and depressive symptoms. This is the first double-blind randomized placebo-controlled clinical trial that explored the modulation of BDNF in response to a psychedelic in patients with depression. The results suggest a potential link between the observed antidepressant effects of ayahuasca and changes in serum BDNF, which contributes to the emerging view of using psychedelics as an antidepressant. This trial is registered at http://clinicaltrials.gov (NCT02914769).

REST: An epigenetic regulator of neuronal stress responses in the young and ageing brain

The transcriptional repressor REST (Repressor Element-1 Silencing Transcription factor) is a key modulator of the neuronal epigenome and targets genes involved in neuronal differentiation, axonal growth, vesicular transport, ion channel conductance and synaptic plasticity. Whilst its gene expression-modifying properties have been examined extensively in neuronal development, REST's response towards stress-induced neuronal insults has only recently been explored. Overall, REST appears to be an ideal candidate to fine-tune neuronal gene expression following different forms of cellular, neuropathological, psychological and physical stressors. Upregulation of REST is reportedly protective against premature neural stem cell depletion, neuronal hyperexcitability, oxidative stress, neuroendocrine system dysfunction and neuropathology. In contrast, neuronal REST activation has also been linked to neuronal dysfunction and neurodegeneration. Here, we highlight key findings and discrepancies surrounding our current understanding of REST's function in neuronal adaptation to stress and explore its potential role in neuronal stress resilience in the young and ageing brain.

Low serum brain-derived neurotrophic factor is associated with suicidal ideation in major depressive disorder

The "neurotrophic hypothesis of depression" posits that low levels of brain-derived neurotrophic factor (BDNF) are associated with Major Depressive Disorder (MDD). Low levels of BDNF have also been found in individuals with suicide attempts, in MDD or other disorders, suggesting that low BDNF may also be associated with suicidality. We assessed serum BDNF in 68 physically healthy and unmedicated (for at least 6 weeks) MDD subjects, who expressed no suicidal ideation (NSI; N = 40) or endorsed suicidal ideation (SI; N = 28), but were not actively suicidal, and in healthy controls (HC; N = 76). Serum BDNF levels were significantly lower in MDD with SI compared to NSI MDD but were not significantly correlated with total Hamilton Depression Rating Scale (HDRS-17) severity or severity on any HDRS subscale. Covarying for age, sex, body mass index, platelets, perceived stress, smoking and physical activity did not alter the significant association between BDNF and SI. SI status was not significantly different between HC and MDD. Our findings show an association between low serum BDNF and SI in individuals with less than severe and non-active suicidal intent, suggesting that the individual symptom of suicidality may extend the neurotrophic hypothesis of depression to include suicidal ideation within MDD.

Translational new approaches for investigating mood disorders in rodents and what they may reveal about the underlying neurobiology of major depressive disorder

Mood disorders represent one of society's most costly and challenging health burdens. The drug treatments used today were initially discovered serendipitously in the 1950s. Animal models were then developed based on the ability of these drugs to alter specific behaviours. These models have played a major role in the development of the second generation of antidepressants. However, their use has been heavily criticized, particularly in relation to whether they recapitulate similar underlying biology to the psychiatric disorder they are proposed to represent. This article considers our work in the field of affective bias and the development of a translational research programme to try to develop and validate better animal models. We discuss whether the new data that have arisen from these studies support an alternative perspective on the underlying neurobiological processes that lead to major depressive disorder (MDD). Specifically, this article will consider whether a neuropsychological mechanism involving affective biases plays a causal role in the development of MDD and its associated emotional and behavioural symptoms. These animal studies also raise the possibility that neuropsychological mechanisms involving affective biases are a precursor to, rather than a consequence of, the neurotrophic changes linked to MDD.

This article is part of a discussion meeting issue ‘Of mice and mental health: facilitating dialogue between basic and clinical neuroscientists’.

BDNF mediates the protective effects of scopolamine in reserpine-induced depression-like behaviors via up-regulation of 5-HTT and TPH1

Reserpine treatment in rodents has been shown to induce depression-like behaviors that mimic monoamine dysfunction implicated in the development of depression. Herein, we aimed to demonstrate the antidepressant-like activities of scopolamine, the muscarinic receptor antagonist, in a reserpine-induced mouse model. Mice were injected with 1.5 mg/kg (i.p.) of reserpine for 10 days, and the depression-like state was confirmed via the open field test (OFT) and forced swimming test (FST). Then, the mice were treated with scopolamine (25 µg/kg, i.p.) or saline for 3 days. Ten days of reserpine treatment resulted in a significant decrease in locomotor activity and an increase in immobility time in the OFT and FST, respectively, indicating that ten days of reserpine administration significantly induced depression-like behaviors in mice. However, scopolamine rapidly ameliorated the increase in immobility time in the FST and had no effect on locomotor activity in the OFT. In addition, the reserpine-induced decreases in serotonin transporter (5-HTT), brain-derived neurotrophic factor (BDNF) and tryptophan hydroxylase 1 (TPH1) in mouse hippocampus and prefrontal cortex (PFC) were significantly reversed by scopolamine. Our study provides evidence that scopolamine rapidly attenuates reserpine-induced depression in mice partially by regulating 5-HTT, BDNF and TPH1 in the hippocampus and PFC of mice.

SiNiSan Ameliorates the Depression-Like Behavior of Rats That Experienced Maternal Separation Through 5-HT1A Receptor/CREB/BDNF Pathway

Background: Early adverse life stress is an important dangerous factor in the development of psychiatric disorders, particularly depression. Available clinical antidepressant agents, such as fluoxetine, [a selective serotonin reuptake inhibitor (SSRI)], are unsatisfactory because of their side effects. SiNiSan (SNS) is a classic Chinese medicine prescription regarded to disperse stagnated liver qi to relieve qi stagnation. Therefore, this study was designed to detect the effects and molecular mechanism of SNS treatment in rats subjected to maternal separation (MS). Method: Male neonatal Wistar rats were divided into six groups including control + ddH₂O, MS + ddH₂O, MS + fluoxetine (5 g/kg), MS + SNS -low dose (2.5 g/kg), MS + SNS -medium dose (5 g/kg), MS + SNS -high dose (10 g/kg). The volume of drugs and ddH2O in each group are according to the weight of rats every day (10 mL/kg). Each group comprised 16 pups with 8 young and 8 adult pups. Except for the control group, all MS groups were separated from their mothers for 4 h/day from 9:00 to 13:00 during postnatal days (PNDs) 1 to 21. After MS, the six groups were intragastrically administered with ddH2O, fluoxetine, and different doses of SNS until PND 28 (for young pups) and PND 56 (for adult pups). The pups were weighed every day, and depression-like behavior was assessed by sucrose preference test, open field test, and forced swimming test. Serotonin 1A (5-HT1A) receptor, phosphorylated protein kinase A (p-PKA) substrate, cAMP response element-binding protein (CREB), p-CREB and brain-derived neurotrophic factor (BDNF) in the hippocampus were examined by Western blot, and in situ 5-HT1A receptor expression was measured by IHC. Results: Young and adult MS rats exhibited depression-like behavior. However, the depression-like behavior was ameliorated by SNS in both age groups. The levels of 5-HT1A receptor, p-CREB, and BDNF in the hippocampus were reduced in young and adult MS rats. SNS treatment significantly up-regulated the expression of 5-HT1A receptor, p-CREB, and BDNF in the hippocampus of adult MS rats. However, few significant effects on the protein expression were observed in the young MS rats. Conclusion: MS in infancy could develop depression-like behavior in young and adult. SNS treatment may perform antidepressant effects on young and adult MS rats through the BDNF/PKA/CREB pathway.

Antidepressant-Like and Neuroprotective Effects of Ethanol Extract from the Root Bark of Hibiscus syriacus L

Hibiscus syriacus L. (Malvaceae) is an important ornamental shrub in horticulture and has been widely used as a medical material in Asia. The aim of this study was to assess the antidepressant and neuroprotective effects of a root bark extract of H. syriacus (HSR) and to investigate the underlying molecular mechanisms. Using an animal model of restraint stress, we investigated the effects of HSR on depressive-like behaviors and on the expression levels of serotonin, corticosterone, and neurotrophic factors in the brain. The mice were exposed to restraint stress for 2 h per day over a period of 3 weeks and orally treated with HSR (100, 200, or 400 mg/kg/day). We also examined the neuroprotective effect of HSR using corticosterone-treated human neuroblastoma SK-N-SH cells. The cells were incubated with the extract for 24 h, followed by corticosterone stimulation for 1 h, and then cell viability assay, cellular ATP assay, mitochondrial membrane potential (MMP) assay, cellular reactive oxygen species (ROS) assay, and western blotting were used to investigate the neuroprotective effects of HSR. Administration of HSR not only reduced the immobility times of the restraint-stressed mice in the forced swimming and tail suspension tests, but also significantly increased sucrose preference in the sucrose preference test. In addition, HSR significantly reduced the plasma levels of corticosterone and increased the brain levels of serotonin. The extract also increased the phosphorylation level of cyclic AMP response element-binding (CREB) protein and the expression level of brain-derived neurotrophic factor (BDNF). The in vitro assays showed that HSR pretreatment increased cell viability and ATP levels, recovered MMP, decreased ROS levels, and increased the expression of CREB and BDNF in corticosterone-induced neurotoxicity. Taken together, our data suggest that HSR may have the potential to control neuronal cell damage and depressive behaviors caused by chronic stress.

Antidepressant-Like Effects of Low- and High-Molecular Weight FGF-2 on Chronic Unpredictable Mild Stress Mice

The occurrence of depressive disorder has long been attributed to changes in monoamines, with the focus of drug treatment strategies being to change the effectiveness of monoamines. However, the success achieved by changing these processes is limited and further stimulates the exploration of alternative mechanisms and treatments. Fibroblast growth factor 2 (FGF-2), which occurs in a high-molecular weight (HMW) and low-molecular weight (LMW) form, is a potent developmental modulator and nervous system regulator that has been suggested to play an important role in various psychiatric disorders. In this study, we investigated the antidepressant effects of HMW and LMW FGF-2 on depression induced by chronic stress. Both peripheral LMW and HMW FGF-2 attenuated the depression-like behaviors in chronic unpredictable mild stress (CUMS) mice to a similar extent, as determined by the forced swimming, tail suspension, and sucrose preference tests. We then showed that CUMS-induced oxidative stresses in mice were inhibited by FGF-2 treatments both in central and peripheral. We also showed that both forms of FGF-2 increased the phosphorylation of ERK and AKT, increased Bcl-2 expression and inhibited caspase-3 activation in CUMS mice. Interestingly, HMW FGF-2 enhanced the activity of the brain-derived neurotrophic factor (BDNF) to a greater extent than did LMW FGF-2 in the hippocampus. Taken together, these results suggest that depressive symptoms can be relieved by administering different forms of FGF-2 peripherally in a CUMS-induced depression model through a similar antidepressant signaling pathway, therefore suggesting a potential clinical use for FGF-2 as a treatment for depression.

Plasma levels of brain-derived neurotrophic factor in patients with Parkinson disease: A systematic review and meta-analysis

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is an abundant neurotrophin in the adult brain. Serum BDNF levels might be used as a proxy for its central expression. Considering conflicting reports, we aimed to answer "How do serum/CSF levels of BDNF change in patients with PD?".

METHODS

We conducted a comprehensive search in MEDLINE, EMBASE and SCOPUS databases including 12 eligible studies. Five studies compared BDNF in serum of PD patients versus healthy controls (HC) and 3 studies provided BDNF levels in sera of non-depressed and depressed PD patients (NDPD and DPD). Review Manager and Software version 3.0 were used for meta-analysis and meta-regressions. Mean difference (MD) was used for measurement of effect size.

RESULTS

PD patients had reduced serum BDNF levels compared to HC (MD = -2.99 ng/mL). Serum BDNF was highest in DPD patients compared to HC (MD = -4.83 ng/mL), with no difference between DPD and NDPD patients in serum BDNF levels. Among co-variates that were eligible for meta-regression, age, sex, and Hoehn and Yahr (H&Y) motor stage had significant positive associations with the effect size in the difference of serum BDNF between patients and HC.

CONCLUSIONS

PD patients had reduced serum BDNF levels compared to HC, regardless of presence of co-morbid depression. PD is at least equally effective in reducing serum BDNF levels as depression. Motor progression predicts serum BDNF downregulation in PD. Acute exercise improves motor function and depressive symptoms in PD probably via BDNF upregulation. The paradoxical rise in serum BDNF in advance PD is probably compensatory in nature.

Nucleocytoplasmic export of HDAC5 and SIRT2 downregulation: two epigenetic mechanisms by which antidepressants enhance synaptic plasticity markers

RATIONALE

Antidepressant action has been linked to increased synaptic plasticity in which epigenetic mechanisms such as histone posttranslational acetylation could be involved. Interestingly, the histone deacetylases HDAC5 and SIRT2 are oppositely regulated by stress and antidepressants in mice prefrontal cortex (PFC). Besides, the neuroblastoma SH-SY5Y line is an in vitro neuronal model reliable to study drug effects with clear advantages over animals.

OBJECTIVES

We aimed to characterize in vitro the role of HDAC5 and SIRT2 in antidepressant regulation of neuroplasticity.

METHODS

SH-SY5Y cultures were incubated with imipramine, fluoxetine, and reboxetine (10 μM, 2 and 24 h) as well as the selective HDAC5 (MC3822, 5 μM, 24 h) or SIRT2 (33i, 5 μM, 24 h) inhibitors. The regulation of the brain-derived neurotrophic factor (BDNF), the vesicular glutamate transporter 1 (VGLUT1), the acetylated histones 3 (AcH3) and 4 (AcH4), HDAC5, and SIRT2 was studied. Comparatively, the long-term effects of these antidepressants (21 days, i.p.) in the mice (C57BL6, 8 weeks) PFC were studied.

RESULTS

Antidepressants increased both in vitro and in vivo expression of BDNF, VGLUT1, AcH3, and AcH4. Moreover, imipramine and reboxetine increased the phosphorylated form of HDAC5 (P-HDAC5), mediating its cytoplasmic export. Further, SIRT2 was downregulated by all antidepressants. Finally, specific inhibition of HDAC5 and SIRT2 increased neuroplasticity markers.

CONCLUSIONS

This study supports the validity of the SH-SY5Y model for studying epigenetic changes linked to synaptic plasticity induced by antidepressants as well as the effect of selective HDAC inhibitors. Particularly, nucleocytoplasmic export of HDAC5 and SIRT2 downregulation mediated by antidepressants could enhance synaptic plasticity markers leading to antidepressant action.

MiR-132, miR-204 and BDNF-TrkB signaling pathway may be involved in spatial learning and memory impairment of the offspring rats caused by fluorine and aluminum exposure during the embryonic stage and into adulthood

Fluorine and aluminium are nervous system poisons, but it remains unclear whether combined fluorine and aluminium exposure damages spatial learning and memory and, if so, by what mechanism. This study showed that exposure to fluorine and aluminium, either alone or combined, during the embryonic stage and into adulthood caused spatial learning and memory impairment in offspring rats; its mechanism may be associated with increases in miR-132 and miR-204 expression and downregulation of the BDNF-TrkB pathway in the hippocampus. The effects of F were obvious, but the effects of Al were slight. There were antagonistic effects between F and Al, with Al reducing the toxicity of F.

Selective Depletion of CREB in Serotonergic Neurons Affects the Upregulation of Brain-Derived Neurotrophic Factor Evoked by Chronic Fluoxetine Treatment

Neurotrophic factors are regarded as crucial regulatory components in neuronal plasticity and are postulated to play an important role in depression pathology. The abundant expression of brain-derived neurotrophic factor (BDNF) in various brain structures seems to be of particular interest in this context, as downregulation of BDNF is postulated to be correlated with depression and its upregulation is often observed after chronic treatment with common antidepressants. It is well-known that BDNF expression is regulated by cyclic AMP response element-binding protein (CREB). In our previous study using mice lacking CREB in serotonergic neurons (Creb1^TPH2CreERT2 mice), we showed that selective CREB ablation in these particular neuronal populations is crucial for drug-resistant phenotypes in the tail suspension test observed after fluoxetine administration in Creb1^TPH2CreERT2 mice. The aim of this study was to investigate the molecular changes in the expression of neurotrophins in Creb1^TPH2CreERT2 mice after chronic fluoxetine treatment, restricted to the brain structures implicated in depression pathology with profound serotonergic innervation including the prefrontal cortex (PFC) and hippocampus. Here, we show for the first time that BDNF upregulation observed after fluoxetine in the hippocampus or PFC might be dependent on the transcription factor CREB residing, not within these particular structures targeted by serotonergic projections, but exclusively in serotonergic neurons. This observation may shed new light on the neurotrophic hypothesis of depression, where the effects of BDNF observed after antidepressants in the hippocampus and other brain structures were rather thought to be regulated by CREB residing within the same brain structures. Overall, these results provide further evidence for the pivotal role of CREB in serotonergic neurons in maintaining mechanisms of antidepressant drug action by regulation of BDNF levels.

Depression and glioblastoma, complicated concomitant diseases: a systemic review of published literature

Glioblastoma multiforme (GBM) is the most common primary brain cancer. Depression is a common co-morbidity of this condition. Despite this common interaction, relatively little research has been performed on the development of GBM-associated depression. We performed a literary search of the PubMed database for articles published relating to GBM and depression. A total of 85 articles were identified with 46 meeting inclusion criteria. Depression significantly impacts care, decreasing medication compliance, and patient survival. Diagnostically, because depression and GBM share intricate neuro-connectivity in a way that effect functionality, these diseases can be mistaken for alternative psychological or pathological disorders, complicating care. Therapeutically, anti-depressants have anti-tumor properties; yet, some have been shown to interfere with GBM treatment. One reason for this is that the pathophysiological development of depression and GBM share several pathways including altered regulation of the 5-HT receptor, norepinephrine, and 3':5'-cyclic monophosphate. Over time, depression can persist after GBM treatment, affecting patient quality of life. Together, depression and GBM are complicated concomitant diseases. Clinicians must be aware of their co-existence. Because of overlapping molecular pathways involved in both diseases, careful medication selection is imperative to avoid potential adverse interactions. Since GBMs are the most common primary brain cancer, physicians dealing with this disease should be prepared for the development of depression as a potential sequela of this condition, given the related pathophysiology and the known poor outcomes.

Long-term Changes in Depressive Symptoms and Estimated Cardiorespiratory Fitness and Risk of All-Cause Mortality: The Nord-Trøndelag Health Study

OBJECTIVE

To assess the independent and combined associations of long-term changes in depressive symptoms (DSs) and estimated cardiorespiratory fitness (eCRF) with all-cause mortality.

PARTICIPANTS AND METHODS

This is a longitudinal cohort study of 15,217 middle-aged and older individuals attending both the second (from August 15, 1995, through June 18, 1997) and third (from October 3, 2006, through June 25, 2008) health surveys of the Nord-Trøndelag Health Study, Norway, and followed until December 31, 2014. Depressive symptoms were estimated using the validated Hospital Anxiety and Depression Scale, and a validated nonexercise model estimated eCRF. Hazard ratios (HRs) were computed using Cox regression. All-cause mortality was ascertained using the Norwegian Cause of Death Registry.

RESULTS

The mean age was 63.3±8.9 years, and 7932 (52.1%) were women. During the follow-up period of 7.1±1.1 years, 1157 participants (7.6%) died. Multivariable-adjusted analyses revealed that persistently low DSs were independently associated with a 28% risk reduction of all-cause mortality (HR, 0.72; 95% CI, 0.56-0.92; P=.008) as compared with persistently high DSs. Persistently high eCRF independently predicted a 26% lower risk of death (HR, 0.76; 95% CI, 0.66-0.88; P<.001) relative to low eCRF. Analyses of changes in DSs and eCRF revealed that persistently high eCRF combined with decreased or persistently low DSs decreased mortality risk by 49% (HR, 0.51; 95% CI, 0.28-0.91; P=.02) and 47% (HR, 0.53; 95% CI, 0.37-0.76, P=.001), respectively.

CONCLUSION

Maintaining low DSs and high eCRF was independently associated with a lower risk of all-cause mortality. The lowest mortality risk was observed for persistently high eCRF combined with decreased or persistently low DSs. These results emphasize the effect of preventing DSs and maintaining high CRF on long-term mortality risk, which is potentially important for long-term population health.

Immune and Neuroprotective Effects of Physical Activity on the Brain in Depression

Physical activity-a lifestyle factor that is associated with immune function, neuroprotection, and energy metabolism-modulates the cellular and molecular processes in the brain that are vital for emotional and cognitive health, collective mechanisms that can go awry in depression. Physical activity optimizes the stress response, neurotransmitter level and function (e.g., serotonergic, noradrenergic, dopaminergic, and glutamatergic), myokine production (e.g., interleukin-6), transcription factor levels and correlates [e.g., peroxisome proliferator-activated receptor C coactivator-1α [PGC-1α], mitochondrial density, nitric oxide pathway activity, Ca2+ signaling, reactive oxygen specie production, and AMP-activated protein kinase [AMPK] activity], kynurenine metabolites, glucose regulation, astrocytic health, and growth factors (e.g., brain-derived neurotrophic factor). Dysregulation of these interrelated processes can effectuate depression, a chronic mental illness that affects millions of individuals worldwide. Although the biogenic amine model has provided some clinical utility in understanding chronic depression, a need remains to better understand the interrelated mechanisms that contribute to immune dysfunction and the means by which various therapeutics mitigate them. Fortunately, convergent evidence suggests that physical activity improves emotional and cognitive function in persons with depression, particularly in those with comorbid inflammation. Accordingly, the aims of this review are to (1) underscore the link between inflammatory correlates and depression, (2) explicate immuno-neuroendocrine foundations, (3) elucidate evidence of neurotransmitter and cytokine crosstalk in depressive pathobiology, (4) determine the immunomodulatory effects of physical activity in depression, (5) examine protocols used to effectuate the positive effects of physical activity in depression, and (6) highlight implications for clinicians and scientists. It is our contention that a deeper understanding of the mechanisms by which inflammation contributes to the pathobiology of depression will translate to novel and more effective treatments, particularly by identifying relevant patient populations that can benefit from immune-based therapies within the context of personalized medicine.

Chronic Hippocampal Abnormalities and Blunted HPA Axis in an Animal Model of Repeated Unpredictable Stress

Incidence of post-traumatic stress disorder (PTSD) ranges from 3 to 30% in individuals exposed to traumatic events, with the highest prevalence in groups exposed to combat, torture, or rape. To date, only a few FDA approved drugs are available to treat PTSD, which only offer symptomatic relief and variable efficacy. There is, therefore, an urgent need to explore new concepts regarding the biological responses causing PTSD. Animal models are an appropriate platform for conducting such studies. Herein, we examined the chronic behavioral and neurobiological effects of repeated unpredictable stress (RUS) in a mouse model. 12 weeks-old C57BL/6J male mice were exposed to a 21-day RUS paradigm consisting of exposures to a predator odor (TMT) whilst under restraint, unstable social housing, inescapable footshocks and social isolation. Validity of the model was assessed by comprehensive examination of behavioral outcomes at an acute timepoint, 3 and 6 months post-RUS; and molecular profiling was also conducted on brain and plasma samples at the acute and 6 months timepoints. Stressed mice demonstrated recall of traumatic memories, passive stress coping behavior, acute anxiety, and weight gain deficits when compared to control mice. Immunoblotting of amygdala lysates showed a dysregulation in the p75NTR/ProBDNF, and glutamatergic signaling in stressed mice at the acute timepoint. At 6 months after RUS, stressed mice had lower plasma corticosterone, reduced hippocampal CA1 volume and reduced brain-derived neurotrophic factor levels. In addition, glucocorticoid regulatory protein FKBP5 was downregulated in the hypothalamus of stressed mice at the same timepoint, together implicating an impaired hypothalamus-pituitary-adrenal-axis. Our model demonstrates chronic behavioral and neurobiological outcomes consistent with those reported in human PTSD cases and thus presents a platform through which to understand the neurobiology of stress and explore new therapeutic interventions.

Antidepressant Effect of Fraxinus rhynchophylla Hance Extract in a Mouse Model of Chronic Stress-Induced Depression

Prolonged exposure to stress can affect mood and cognition and lead to mood disorders. Research on stress-associated mood disorders is important in modern society as people are increasingly exposed to unavoidable stressors. We used a mouse model with 2 weeks of exposure to electric foot shock and restraint, to determine the effect of Fraxinus rhynchophylla Hance (FX) extract on chronic stress-induced depression. We measured the effect of FX extract using various physiological, behavioral, and biochemical measures. FX extract ameliorated chronic stress-induced body and relative liver weight loss and improved depressive-like behaviors in the open field and forced swim tests. In addition, plasma cortisol and serotonin levels in stress-induced mice following FX treatment were similar to normal mice, and the elevation of proinflammatory cytokines was prevented. Moreover, FX treatment increased the expression of phosphorylated cyclic adenosine-3′,5′-monophosphate response element-binding protein (pCREB)/brain-derived neurotrophic factor (BDNF). Further experiments confirmed the efficacy of FX extract by showing similar results using esculin and esculetin, compounds extracted from FX. Taken together, these results indicate that FX extract has an antidepressant effect on chronic stress-induced depression by associating signaling with neuroinflammation and neurogenesis.

The Effects of Moderate Physical Exercise on Adult Cognition: A Systematic Review

Background: Physical exercise is a systematic sequence of movements executed with a predefined purpose. This muscular activity impacts not only on circulatory adaptations, but also neuronal integration with the potential to influence cognition. The aim of this review was to determine whether the literature supports the idea that physical exercise promotes cognitive benefits in healthy adults.

Methods: A systematic search for relevant articles was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis criteria using available databases (PubMed, LILACS, Scopus, Web of Science, The Cochrane Library, OpenGrey, Google Scholar and CENTRAL). The search terms included “humans” or “adults” or “cognition” or “awareness” or “cognitive dissonance” or “cognitive reserve” or “comprehension” or “consciousness” and “motor activity” or “exercise” or “physical fitness,” and not “aged” or “nervous system diseases,” with the purpose of finding associations between moderate physical exercise and cognition. A methodological quality and risk of bias unit assessed the eligibility of articles.

Results: A total of 7179 articles were identified. Following review and quality assessment, three articles were identified to fulfill the inclusion criteria. An association between moderate physical exercise and cognition was observed. Improvements in cognitive parameters such as reduced simple reaction time, improved response precision and working memory were identified among the included articles.

Conclusion: This systematic review found that moderate physical exercise improves cognition.

Mechanisms of Transcranial Magnetic Stimulation Treating on Post-stroke Depression

Post-stroke depression (PSD) is a neuropsychiatric affective disorder that can develop after stroke. Patients with PSD show poorer functional and recovery outcomes than patients with stroke who do not suffer from depression. The risk of suicide is also higher in patients with PSD. PSD appears to be associated with complex pathophysiological mechanisms involving both psychological and psychiatric problems that are associated with functional deficits and neurochemical changes secondary to brain damage. Transcranial magnetic stimulation (TMS) is a non-invasive way to investigate cortical excitability via magnetic stimulation of the brain. TMS is currently a valuable tool that can help us understand the pathophysiology of PSD. Although repetitive TMS (rTMS) is an effective treatment for patients with PSD, its mechanism of action remains unknown. Here, we review the known mechanisms underlying rTMS as a tool for better understanding PSD pathophysiology. It should be helpful when considering using rTMS as a therapeutic strategy for PSD.

Beneficial effect of etazolate on depression-like behavior and, learning, and memory impairment in a model of Parkinson's disease

The aim of this study was to evaluate etazolate against depression-like behavior and, learning and memory impairment induced by 6- hydroxydopamine (6-OHDA) rat model of Parkinson's disease (PD). This aim was achieved through comparing 6-OHDA lesioned rats in the presence and absence of etazolate. The 6-OHDA was used to induce lesion as a model of PD. Etazolate was administered at a dose of 1 mg/kg/day for 14 days, starting 7 days after lesion induction. Apomorphine-induced rotation test was used to evaluate 6-OHDA-induced motor deficits, tail suspension test was used to assess depression-like symptoms, and the radial arms water maze (RAWM) was used to evaluate special learning and memory functions. Antioxidant biomarkers and BDNF protein levels were assessed in the hippocampus. Results revealed that etazolate administration significantly improved 6-OHDA-induced PD related symptoms including motor deficits, depression-like behavior and impairment of both short- and long- term memory. Moreover, etazolate significantly prevented 6-OHDA-induced reduction in oxidative stress biomarkers (GSH/GSSG ratio, GPx) and BDNF levels. In conclusion, motor dysfunction, depressive- like behavior, and learning and memory deficits in the 6-OHDA rat model of PD can be significantly prevented by etazolate. This prevention could be attributed to etazolate's ability to prevent reduction in antioxidative stress biomarkers and BDNF levels.

Antidepression action of BDNF requires and is mimicked by Gαi1/3 expression in the hippocampus

Stress-related alterations in brain-derived neurotrophic factor (BDNF) expression, a neurotrophin that plays a key role in synaptic plasticity, are believed to contribute to the pathophysiology of depression. Here, we show that in a chronic mild stress (CMS) model of depression the Gαi1 and Gαi3 subunits of heterotrimeric G proteins are down-regulated in the hippocampus, a key limbic structure associated with major depressive disorder. We provide evidence that Gαi1 and Gαi3 (Gαi1/3) are required for the activation of TrkB downstream signaling pathways. In mouse embryonic fibroblasts (MEFs) and CNS neurons, Gαi1/3 knockdown inhibited BDNF-induced tropomyosin-related kinase B (TrkB) endocytosis, adaptor protein activation, and Akt-mTORC1 and Erk-MAPK signaling. Functional studies show that Gαi1 and Gαi3 knockdown decreases the number of dendrites and dendritic spines in hippocampal neurons. In vivo, hippocampal Gαi1/3 knockdown after bilateral microinjection of lentiviral constructs containing Gαi1 and Gαi3 shRNA elicited depressive behaviors. Critically, exogenous expression of Gαi3 in the hippocampus reversed depressive behaviors in CMS mice. Similar results were observed in Gαi1/Gαi3 double-knockout mice, which exhibited severe depressive behaviors. These results demonstrate that heterotrimeric Gαi1 and Gαi3 proteins are essential for TrkB signaling and that disruption of Gαi1 or Gαi3 function could contribute to depressive behaviors.