Val66Met functional polymorphism and serum protein level of brain-derived neurotrophic factor (BDNF) in acute episode of schizophrenia and depression

Serum brain-derived neurotrophic factor, Val66Met polymorphism and open-label SSRI treatment response in Major Depressive Disorder

BACKGROUND

Brain-derived neurotrophic factor (BDNF) has been implicated in the therapeutic action of antidepressants and possibly in the pathophysiology of Major Depressive Disorder (MDD). Clinical studies of peripheral blood levels of BDNF in MDD have provided conflicting results, and there are also conflicting reports regarding the predictive value of peripheral BDNF levels for antidepressant treatment response. The present study investigated the association between serum BDNF levels, the BDNF Val66Met polymorphism (rs6265), clinical characteristics and SSRI treatment response.

METHODS

This open-label clinical trial included 99 physically healthy, unmedicated MDD participants and 70 healthy controls. Following a baseline assessment, 53 of the MDD participants completed an eight-week, open-label course of SSRI antidepressant treatment. Serum BDNF levels and Hamilton Rating Scale for Depression (HDRS) ratings were examined at baseline and after eight weeks of treatment. Antidepressant response was defined as a decrease in HDRS ratings of > 50% from baseline to the end-of-treatment. Finally, serum BDNF levels and SSRI treatment response were compared between MDD participants who were heterozygous or homozygous for the Met allele ("Met-carriers") and individuals homozygous for the Val allele.

RESULTS

Serum BDNF levels at baseline were significantly higher in the unmedicated MDD participants compared to healthy controls (15.90 ng/ml vs 13.75 ng/ml, t (167) = -2.041, p = 0.043). In a post-hoc analysis, this difference was seen in the female but not male participants (16.85 ng/ml vs 14.06 ng/ml, t (91) = -2.067, p = 0.042; 14.86 ng/ml vs 13.31 ng/ml, t (74) = -0.923, p = 0.359). Baseline serum BDNF levels were not associated with treatment responder status or with absolute change in depression ratings over the course of 8-week SSRI treatment (p = 0.599). In both Responders and Non-responders, no significant changes in serum BDNF levels were found over the 8-week period of SSRI-treatment (16.32 ng/ml vs 16.23 ng/ml, t (18) = 0.060, p = 0.953; 16.04 ng/ml vs 15.61 ng/ml, t (29) = 0.438, p = 0.665, respectively). Further, no differences were found in serum BDNF levels prior to treatment between MDD Met-carriers and MDD Val/Val homozygotes (15.32 ng/ml vs 16.36 ng/ml, t (85) = 0.747, p = 0.457), and no differences were found in post-treatment serum BDNF (F1,42= 0.031, p = 0.862). However, MDD Val/Val homozygotes showed significantly greater antidepressant responses at week 8 than did MDD Met-carriers (F1,46 = 4.366, p = 0.043).

CONCLUSION

Our results do not support sufficient reliability of using peripheral BDNF to characterize depression or to predict antidepressant response in clinical use. The role of sex in moderating BDNF differences in depression, and the role of BDNF gene polymorphisms in predicting antidepressant response, remain to be further investigated. We conclude that, while central nervous system BDNF is likely involved in antidepressant efficacy and in aspects of MDD pathophysiology, its reflection in serum BDNF levels is of limited diagnostic or prognostic utility.

Changes in BDNF methylation patterns after cognitive remediation therapy in schizophrenia: A randomized and controlled trial

Although cognitive remediation therapy (CRT) produces cognitive benefits in schizophrenia, we do not yet understand whether molecular changes are associated with this cognitive improvement. A gene central to synaptic plasticity, the BDNF, has been proposed as one potential route. This study assesses whether BDNF methylation changes following CRT-produced cognitive improvement are detected. A randomized and controlled trial was performed with two groups (CRT, n = 40; TAU: Treatment as Usual, n = 20) on a sample of participants with schizophrenia. CRT was delivered by trained therapists using a web-based computerized program. Mixed Models, where the interaction of treatment (CRT, TAU) by time (T0: 0 weeks, T1: 16 weeks) was the main effect were used. Then, we tested the association between the treatment and methylation changes in three CpG islands of the BDNF gene. CRT group showed significant improvements in some cognitive domains. Between-groups differential changes in 5 CpG units over time were found, 4 in island 1 (CpG1.2, CpG1.7, CpG1.10, CpG1.17) and 1 in island 3 (CpG3.2). CRT group showed increases in methylation in CpG1.2, CpG1.7 and decreases in pG1.10, CpG1.17, and CpG3.2. Differences in the degree of methylation were associated with changes in Speed of Processing, Working Memory, and Verbal Learning within the CRT group. Those findings provide new data on the relationship between cognitive improvement and changes in peripheral methylation levels of BDNF gene, a key factor involved in neuroplasticity regulation. Trial Registration: NCT04278027.

Schizophrenia in the genetic era: a review from development history, clinical features and genomic research approaches to insights of susceptibility genes

Schizophrenia is a devastating neuropsychiatric disorder affecting 1% of the world population and ranks as one of the disorders providing the most severe burden for society. Schizophrenia etiology remains obscure involving multi-risk factors, such as genetic, environmental, nutritional, and developmental factors. Complex interactions of genetic and environmental factors have been implicated in the etiology of schizophrenia. This review provides an overview of the historical origins, pathophysiological mechanisms, diagnosis, clinical symptoms and corresponding treatment of schizophrenia. In addition, as schizophrenia is a polygenic, genetic disorder caused by the combined action of multiple micro-effective genes, we further detail several approaches, such as candidate gene association study (CGAS) and genome-wide association study (GWAS), which are commonly used in schizophrenia genomics studies. A number of GWASs about schizophrenia have been performed with the hope to identify novel, consistent and influential risk genetic factors. Finally, some schizophrenia susceptibility genes have been identified and reported in recent years and their biological functions are also listed. This review may serve as a summary of past research on schizophrenia genomics and susceptibility genes (NRG1, DISC1, RELN, BDNF, MSI2), which may point the way to future schizophrenia genetics research. In addition, depending on the above discovery of susceptibility genes and their exact function, the development and application of antipsychotic drugs will be promoted in the future.

The Influence of Electroconvulsive Therapy (ECT) on Brain-Derived Neurotrophic Factor (BDNF) Plasma Level in Patients with Schizophrenia-A Systematic Review and Meta-Analysis

The main aim of this systematic review and meta-analysis is to establish whether there is a correlation between the brain-derived neurotrophic factor (BDNF) level and electroconvulsive therapy (ECT) treatment and the reduction in psychotic symptoms in patients diagnosed with schizophrenia. A systematic search of PubMed/Medline, Cochrane Library, Web of Science, Scopus and Embase was conducted up to March 2023. Inclusion criteria: studies in which adult patients with schizophrenia treated with antipsychotic medication received ECT therapy and had the BDNF level measured before and after ECT treatment. Exclusion criteria: animal and in vitro studies or studies not involving complete information about the treatment and concentration of BDNF in plasma. The risk of bias was assessed using Egger's regression-based test for meta-analysis with continuous outcomes. Six studies comprising 248 individuals with schizophrenia were included. A statistically significant increase in BDNF levels after ECT treatment was observed only in two studies (p < 0.001 and p < 0.027, respectively), whereas in four other studies, an upward trend without statistical significance was noticed. The estimated overall size effect revealed that ECT therapy caused a slight change in the BDNF level but without statistical significance (ES = -0.328). Different numbers of ECT procedures (4-10), final measurement of the BDNF level made at a different time point, using bilateral or unilateral electrode positioning during ECT and treatment with different combinations of typical or atypical antipsychotic medications may be potential reasons for the lack of statistical significance in the changes in BDNF levels after treatment. Data regarding the measurement of BDNF levels pre and post ECT therapy in patients with schizophrenia are very limited without an extended follow-up period and evaluation of mental health change. Our meta-analysis showed that treatment with ECT therapy and antipsychotic medication increases serum BDNF levels in patients with drug-resistant schizophrenia compared to patients treated with medication only; however, this effect is not statistically significant.

Elevated Plasma Levels of Mature Brain-Derived Neurotrophic Factor in Major Depressive Disorder Patients with Higher Suicidal Ideation

Several pieces of evidence show that signaling via brain-derived neurotrophic factor (BDNF) and its receptor, tropomycin receptor kinase B (TrkB), as well as inflammation, play a crucial part in the pathophysiology of depression. The purpose of our study was to evaluate plasma levels of BDNF-TrkB signaling, which are inflammatory factors in major depressive disorder (MDD) patients, and assess their associations with clinical performance. This study recruited a total sample of 83 MDD patients and 93 healthy controls (CON). All the participants were tested with the Hamilton Depression Scale (HAMD), the Beck Scale for Suicide Ideation, and the NEO Five-Factor Inventory. The plasma level of selected BDNF-TrkB signaling components (mature BDNF (mBDNF), precursor BDNF (proBDNF), tyrosine kinase B (TrkB), and tissue plasminogen activator (tPA)) and selected inflammatory factors (interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α)) were measured using an enzyme-linked immunosorbent assay (ELISA). Further, we performed correlation analysis to indicate the relationship between the plasma levels of the factors and clinical characteristics. Results: (i) A higher level of mBDNF and lower openness were observed in MDD patients with higher suicidal ideation than patients with lower suicidal ideation. (ii) In MDD patients, mBDNF was positively correlated with the sum score of the Beck Scale for Suicide Ideation (BSS). (iii) The levels of mBDNF, tPA, IL-1 β and IL-6 were significantly higher in all MDD subjects compared to the healthy controls, while the levels of TrkB and proBDNF were lower in MDD subjects. Conclusion: Our study provides novel insights regarding the potential role of mBDNF in the neurobiology of the association between depression and suicidal ideation and, in particular, the relationship between BDNF-TrkB signaling, inflammatory factors, and clinical characteristics in MDD.

Association between the BDNF Val66Met polymorphism and major depressive disorder: a systematic review and meta-analysis

Study objectives

This meta-analysis analytically reviewed recent studies concerning the potential associations between the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and susceptibility to major depressive disorder (MDD), with subgroup analyses for race and age.

Methods

Relevant case-control studies were systematically searched for in PubMed, Embase, the Web of Science, China National Knowledge Infrastructure (CNKI), Wanfang, and Sinomed databases. A total of 24 studies were finally identified to have reported outcomes including alleles, dominant genes, recessive genes, homozygosity, and heterozygosity. Subgroup meta-analyses were performed based on participant age and ethnicity. Publication bias was represented by funnel plots. All meta-analyses of the randomized controlled trials included for evaluation were performed using RevMan5.3 software.

Results

The findings revealed no significant association between BDNF Val66Met polymorphism and MDD. However, the Met allele was found to be associated with genetic susceptibility to MDD among white populations on subgroup analysis (OR = 1.25, 95% CI: 1.05-1.48, P = 0.01). In the genetic model, dominant (OR = 1.40, 95% CI: 1.18-1.66, P = 0.0001), recessive (OR = 1.70, 95% CI: 1.05-2.78, P = 0.03), and homozygous (OR = 1.77, 95% CI: 1.08-2.88, P = 0.02) genes were all associated with MDD.

Conclusions

Despite the outcome limitations, this meta-analysis confirmed that the BDNF Val66Met polymorphism is a susceptibility factor for MDD in white populations.

Dysregulation of Synaptic Plasticity Markers in Schizophrenia

Schizophrenia is a mental disorder characterized by cognitive impairment resulting in compromised quality of life. Since the regulation of synaptic plasticity has functional implications in various aspects of cognition such as learning, memory, and neural circuit maturation, the dysregulation of synaptic plasticity is considered as a pathobiological feature of schizophrenia. The findings from our recently concluded studies indicate that there is an alteration in levels of synaptic plasticity markers such as neural cell adhesion molecule-1 (NCAM-1), Neurotropin-3 (NT-3) and Matrix-mettaloproteinase-9 (MMP-9) in schizophrenia patients. The objective of the present article is to review the role of markers of synaptic plasticity in schizophrenia. PubMed database (http;//www.ncbi.nlm.nih.gov/pubmed) was used to perform an extensive literature search using the keywords schizophrenia and synaptic plasticity. We conclude that markers of synaptic plasticity are altered in schizophrenia and may lead to complications of schizophrenia including cognitive dysfunction.

Sublingual buprenorphine/naloxone treatment is not affected by OPRM1 A118G and BDNF Va66Met polymorphisms, but alters the plasma beta-endorphin and BDNF levels in individuals with opioid use disorder

The study aimed to examine the genetic contribution to buprenorphine (BUP) treatment in individuals with opioid use disorder (OUD), with a specific focus on BDNF and OPRM1 genes. A total of 113 controls and 111 OUD patients receiving sublingual BUP/naloxone were enrolled. OPRM1 A118G and BDNF Val66Met polymorphisms were investigated by PCR-FRLP. Plasma BDNF and beta-endorphin levels were assessed by ELISA kits in both groups. Blood BUP levels were measured by LC-MS/MS and normalized with daily BUP dose (BUP/D). OPRM1 A118G and BDNF Val66Met polymorphisms didn't have an effect on plasma beta-endorphin and BDNF levels in OUD patients, respectively. Interestingly, OUD patients had significantly higher plasma BDNF and lower beta-endorphin levels compared to the controls (p < 0.001). A negative and significant correlation between plasma BUP/D and BDNF levels was found. Age onset of first use was associated with OPRM1 A118G polymorphism. The findings indicated that sublingual BUP/naloxone may increase plasma BDNF levels, but may decrease beta-endorphin levels in individuals with OUD. Plasma BDNF level seemed to be decreased in a BUP/D concentration-dependent manner.

Serum brain-derived neurotrophic factor and glial cell-derived neurotrophic factor in patients with first-episode depression at different ages

OBJECTIVES

We investigated the differences in serum brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) levels and clinical symptoms with first-episode depression at different ages.

METHODS

Ninety patients (15-60 years old) diagnosed with first-episode depression were enrolled as the study group, and they were divided into early-onset, adult and late-onset groups. The age-matched control groups were healthy volunteers. Serum BDNF and GDNF concentrations were determined by enzyme-linked immunosorbent assay (ELISA). GraphPad Prism 9 was used for t tests, one-way ANOVAs, chi-square tests, and correlation analyses. p < 0.05 indicated significant differences.

RESULTS

Serum BDNF and GDNF levels were lower in the whole study group and the three subgroups than in the healthy groups. Illness severity, anxiety and education were higher in the early-onset than late-onset patients. Serum BDNF levels were lower in the adult than late-onset patients. Serum BDNF levels were negatively correlated with patient CGI-SI scores. After the LSD test for multiple comparisons, the results were also significant.

CONCLUSIONS

Low serum BDNF and GDNF levels may be involved in the pathophysiology of first-episode depression, and there were differences in serum BDNF levels at different ages, verifying that serum BDNF and GDNF could serve as potential biomarkers of depression. KEY POINTSDepression is often conceptualised as a systemic illness with different biological mechanisms, but satisfactory explanations have not been provided thus far.The aim of our study was to investigate differences in serum BDNF and GDNF levels and their relationships with clinical symptoms in patients with first-episode depression at different ages.The potential of the neurotrophic factor hypothesis to advance the diagnosis and treatment of depression will be a very exciting new strategy for future research.

New Frontiers in Neurodegeneration and Regeneration Associated with Brain-Derived Neurotrophic Factor and the rs6265 Single Nucleotide Polymorphism

Brain-derived neurotrophic factor is an extensively studied neurotrophin implicated in the pathology of multiple neurodegenerative and psychiatric disorders including, but not limited to, Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, traumatic brain injury, major de-pressive disorder, and schizophrenia. Here we provide a brief summary of current knowledge on the role of BDNF and the common human single nucleotide polymorphism, rs6265, in driving the pathogenesis and rehabilitation in these disorders, as well as the status of BDNF-targeted therapies. A common trend has emerged correlating low BDNF levels, either detected within the central nervous system or peripherally, to disease states, suggesting that BDNF replacement therapies may hold clinical promise. In addition, we introduce evidence for a distinct role of the BDNF pro-peptide as a biologically active ligand and the need for continuing studies on its neurological function outside of that as a molecular chaperone. Finally, we highlight the latest research describing the role of rs6265 expression in mechanisms of neurodegeneration as well as paradoxical advances in the understanding of this genetic variant in neuroregeneration. All of this is discussed in the context of personalized medicine, acknowledging there is no “one size fits all” therapy for neurodegenerative or psychiatric disorders and that continued study of the multiple BDNF isoforms and genetic variants represents an avenue for discovery ripe with therapeutic potential.

Brain-derived neurotrophic factor and inflammation in depression: Pathogenic partners in crime?

Major depressive disorder is a debilitating disorder affecting millions of people each year. Brain-derived neurotrophic factor (BDNF) and inflammation are two prominent biologic risk factors in the pathogenesis of depression that have received considerable attention. Many clinical and animal studies have highlighted associations between low levels of BDNF or high levels of inflammatory markers and the development of behavioral symptoms of depression. However, less is known about potential interaction between BDNF and inflammation, particularly within the central nervous system. Emerging evidence suggests that there is bidirectional regulation between these factors with important implications for the development of depressive symptoms and anti-depressant response. Elevated levels of inflammatory mediators have been shown to reduce expression of BDNF, and BDNF may play an important negative regulatory role on inflammation within the brain. Understanding this interaction more fully within the context of neuropsychiatric disease is important for both developing a fuller understanding of biological pathogenesis of depression and for identifying novel therapeutic opportunities. Here we review these two prominent risk factors for depression with a particular focus on pathogenic implications of their interaction.

Association Between Depressive Symptoms and Serum Brain-Derived Neurotrophic Factor Levels in Patients With First-Episode and Drug-Naïve Schizophrenia

Previous studies have revealed that brain-derived neurotrophic factor (BDNF) levels are inversely associated with the severity of depressive symptoms. In addition, serum BDNF levels tend to increase with improvement in depressive symptoms. There is also evidence that BDNF has a possible role in the pathophysiology of schizophrenia. Therefore, the purpose of this study was to determine whether BDNF levels correlated with depressive symptoms in patients with first-episode and drug-naïve (FEDN) schizophrenia. In this study, 90 patients with FEDN schizophrenia and 60 healthy controls were recruited. The Positive and Negative Syndrome Scale (PANSS) and the 17-item Hamilton Depression Scale (HAMD-17) were used to gage psychopathological and depressive symptoms, respectively. All participants had their BDNF levels measured using a sandwich enzyme-linked immunosorbent test. Serum BDNF levels were lower in patients with FEDN schizophrenia compared with healthy controls. Moreover, patients with depressive symptoms exhibited a higher PANSS total score and a higher general psychopathology score than those without depressive symptoms (p < 0.05). For patients with depressive symptoms, serum BDNF levels were higher than in those without depressive symptoms (p < 0.05). An association between BDNF levels and the positive subscore was also observed (p < 0.01). However, there was no significant association between BDNF levels and HAMD scores (p > 0.05). In conclusion, BDNF levels were shown to be higher in the serum of patients with FEDN schizophrenia with depressive symptoms than in those without. Additionally, low levels of serum BDNF may contribute to the positive symptoms of FEDN schizophrenia but not to depressive symptoms.

The Val66 and Met66 Alleles-Specific Expression of BDNF in Human Muscle and Their Metabolic Responsivity

Brain-derived neurotrophic factor (BDNF) plays an essential role in nervous system formation and functioning, including metabolism. Present only in humans, the “Val66Met” polymorphism of the BDNF gene (BDNF) is suggested to have a negative influence on the etiology of neurological diseases. However, this polymorphism has only been addressed, at the molecular level, in nonhuman models. Knowledge about Val66- and Met66-variant differences, to date, has been achieved at the protein level using either cell culture or animal models. Thus, the purpose of our study was to analyze the impact of the Val66Met polymorphism on BDNF expression in healthy humans and compare the allele-specific responses to metabolic stress. Muscle biopsies from 13 male recreational athletes (34 ± 9 years, 1.80 ± 0.08 m, 76.4 ± 10.5 kg) were obtained before and immediately following a VO₂max test. Allele-specific BDNF mRNA concentrations were quantified by droplet digital PCR (ddPCR) in heterozygous and homozygous subjects. The results indicated that BDNF expression levels were influenced by the genotype according to the presence of the polymorphism. BDNF expression from the Met66-coding alleles, in heterozygotes, was 1.3-fold lower than that from the Val66-coding alleles. Total BDNF mRNA levels in these heterozygotes remained below the whole sample’s mean. A partial dominance was detected for the Val66-coding variant on the Met66-coding’s. BDNF expression levels decreased by an average of 1.8-fold following the VO₂max test, independent of the individual’s genotype. The results of this study indicate that metabolic stress downregulates BDNF expression but not plasma BDNF concentrations. No correlation between expression level and plasma BDNF concentrations was found.

Lack of association between BDNF rs6265 polymorphism and risk of type 2 diabetes: A protocol for meta-analysis and trial sequential analysis

BACKGROUND

Brain-derived neurotrophic factor (BDNF) rs6265 polymorphism has been previously suggested to be associated with the susceptibility of type 2 diabetes mellitus (T2DM), but results remained controversial. We aim to provide a more reliable conclusion about the association between BDNF rs6265 polymorphism and T2DM risk by using a meta-analysis.

METHODS

Electronic databases such as Pubmed, Embase, CNKI, and Wanfang were searched for relevant articles published up to May 06, 2020. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the strength of the associations. Subgroup analysis was carried out according to source of controls and quality score of included studies. A trial sequential analysis was conducted to reduce the risk of type I error.

RESULTS

A total of 8 case-control studies (7 conducted in China) with 1576 T2DM patients and 1866 controls were included. Overall, our results indicated no significant association between BDNF rs6265 polymorphism and T2DM risk with the random-effects model (allele model: pooled OR = 1.14, 95% CI = 0.79-1.65, homozygote model: pooled OR = 1.13, 95% CI = 0.57-2.21, heterozygote model: pooled OR = 1.07, 95% CI = 0.78-1.48, dominant model: pooled OR = 1.14, 95% CI = 0.74-1.75 and recessive model: pooled OR = 1.10, 95% CI = 0.67-1.80). Subgroup analysis by source of controls and quality score also showed no significant association between BDNF rs6265 polymorphism and T2DM risk. Trial sequential analysis results confirmed the null association and further studies were unnecessary.

CONCLUSION

This meta-analysis study indicated that no significant association between BDNF rs6265 polymorphism and T2DM risk.

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.

Association Analysis of 14 Candidate Gene Polymorphism with Depression and Stress among Gestational Diabetes Mellitus

The association of candidate genes and psychological symptoms of depression, anxiety, and stress among women with gestational diabetes mellitus (GDM) in Malaysia was determined in this study, followed by the determination of their odds of getting psychological symptoms, adjusted for socio-demographical background, maternal, and clinical characteristics. Single nucleotide polymorphisms (SNPs) recorded a significant association between SNP of EPHX2 (rs17466684) and depression symptoms (AOR = 7.854, 95% CI = 1.330–46.360) and stress symptoms (AOR = 7.664, 95% CI = 1.579–37.197). Associations were also observed between stress symptoms and SNP of OXTR (rs53576) and (AOR = 2.981, 95% CI = 1.058–8.402) and SNP of NRG1 (rs2919375) (AOR = 9.894, 95% CI = 1.159–84.427). The SNP of EPHX2 (rs17466684) gene polymorphism is associated with depression symptoms among Malaysian women with GDM. SNP of EPHX2 (rs17466684), OXTR (rs53576) and NRG1 (rs2919375) are also associated with stress symptoms.

Peripheral blood BDNF-TrkB signaling in first-episode, drug-free patients with major depressive disorder and schizophrenia

Brain-derived neurotrophic factor (BDNF) has been implicated in the pathogenesis of psychiatric disorders, and studies have shown BDNF aberrations in major psychiatric diseases including schizophrenia (SCZ) and major depressive disorder (MDD). However, data from clinical studies were inconsistent. In this study, we recruited 34 patients with MDD, 77 patients with SCZ and 65 healthy control (HC) subjects to clarify the circulating BDNF levels in MDD and SCZ patients, and to assess whether serum BDNF levels were associated with the disease severity. Our results showed that serum BDNF levels were significantly decreased in the patients with SCZ (Mean difference = -4.517, 95%CI of difference = -7.854 to -1.180, p < 0.01) and MDD (Mean difference = -5.699, 95%CI of difference = -9.892 to -1.506, p < 0.01) when compared with HC subjects. Sub-group analyses suggested that BDNF levels were significantly reduced in the female SCZ (Mean difference = -5.700, 95%CI of difference = -10.21 to -1.189, p < 0.01) and MDD (Mean difference = -5.840, 95%CI of difference = -10.66 to -1.019, p < 0.05) patients, but not in male patients. Further analyses indicated that serum BDNF levels were not correlated with disease severity of MDD and SCZ. In addition, the transcriptional expression of TrkB was significantly down-regulated in the blood of MDD patients, but not in SCZ patients. However, there was no significant correlation between BDNF concentrations and TrkB mRNA levels. Taken together, our results revealed differential changes of BDNF-TrkB signaling in MDD and SCZ patients, therefore contributed to a better understanding of MDD and SCZ pathophysiology.

BDNF and Cortisol integrative system - Plasticity vs. degeneration: Implications of the Val66Met polymorphism

BDNF is the neurotrophin mediating pro-neuronal survival and plasticity. Cortisol (COR), in turn, is engaged in the coordination of several processes in the brain homeostasis. Stress-responsive, both factors show an integrative role through their receptor's dynamics in neurophysiology. Furthermore, the Val66Met BDNF polymorphism may play a role in this mechanism.

AIM

to investigate BDNF-COR interaction in the human neurophysiology context.

METHODS

We collected all papers containing BDNF and COR parameters or showing COR analyses in genotyped individuals in a PubMed search - full description available on PROSPERO - CRD42016050206.

DISCUSSION

BDNF and COR perform distinct roles in the physiology of the brain whose systems are integrated by glucocorticoid receptors dynamics. The BDNF polymorphism appears to have an influence on individual COR responsivity to stress. BDNF and COR play complementary roles in the nervous system where COR is a regulator of positive/negative effects. Exercise positively regulates both factors, regardless of BDNF polymorphism.

BDNF Genotype and Baseline Serum Levels in Relation to Electroconvulsive Therapy Effectiveness in Treatment-Resistant Depressed Patients

OBJECTIVES

Electroconvulsive therapy (ECT) represents one of the most effective therapies for treatment-resistant depression (TRD). The brain-derived neurotrophic factor (BDNF) is a neurotrophin implicated in major depressive disorder and in the effects of different therapeutic approaches, including ECT. Both BDNF peripheral levels and Val66Met polymorphism have been suggested as biomarkers of treatment effectiveness. The objective of this study was to test the potential of serum BDNF levels and Val66Met polymorphism in predicting ECT outcome in TRD patients.

METHODS

Seventy-four TRD patients scheduled to undergo ECT were included in the study. Illness severity was assessed through the Montgomery and Asberg Depression Rating Scale before beginning ECT (T0), the day after the end of ECT (T1), and 1 month after the end of ECT (T2). At T1, patients were classified as responders/nonresponders and remitters/nonremitters, whereas at T2, they were classified as sustained responders/nonresponders and sustained remitters/nonremitters. Serum concentrations of BDNF were measured at T0, and the BDNF Val66Met polymorphism was genotyped.

RESULTS

No difference in BDNF concentrations was observed in responders versus nonresponders, in remitters versus nonremitters, in sustained responders versus sustained nonresponders, and in sustained remitters versus sustained nonremitters. No association of Val66Met polymorphism was detected with both the response and the remission status.

CONCLUSIONS

Baseline serum BDNF levels and the BDNF Val66Met polymorphism showed no clinical utility in predicting ECT outcome in TRD patients.

BDNF, Brain, and Regeneration: Insights from Zebrafish

Zebrafish (Danio rerio) is a teleost fish widely accepted as a model organism for neuroscientific studies. The adults show common basic vertebrate brain structures, together with similar key neuroanatomical and neurochemical pathways of relevance to human diseases. However, the brain of adult zebrafish possesses, differently from mammals, intense neurogenic activity, which can be correlated with high regenerative properties. Brain derived neurotrophic factor (BDNF), a member of the neurotrophin family, has multiple roles in the brain, due also to the existence of several biologically active isoforms, that interact with different types of receptors. BDNF is well conserved in the vertebrate evolution, with the primary amino acid sequences of zebrafish and human BDNF being 91% identical. Here, we review the available literature regarding BDNF in the vertebrate brain and the potential involvement of BDNF in telencephalic regeneration after injury, with particular emphasis to the zebrafish. Finally, we highlight the potential of the zebrafish brain as a valuable model to add new insights on future BDNF studies.