Effects Of Brain-derived Neurotrophic Factor Research Articles

APOE×BDNF Interaction and Poorer Cognitive Outcomes Among Veterans With Mild Traumatic Brain Injury: An Exploratory Study.

The authors examined the interaction between apolipoprotein E (APOE) ε4 and brain-derived neurotrophic factor (BDNF) Val66Met alleles on neuropsychological functioning among veterans with histories of mild traumatic brain injury (mTBI). Participants were 78 veterans with mTBI (85% males; mean±SD age=32.95±7.00 years; mean time since injury=67.97±34.98 months) who completed a structured clinical interview and underwent a comprehensive neuropsychological assessment. Participants also provided a buccal swab for determination of their APOE and BDNF genotypes. Three cognitive composite scores were calculated from the neuropsychological assessment, reflecting visuospatial speed (seven variables), executive functioning (10 variables), and memory (eight variables). Two-way analyses of covariance (ANCOVAs) adjusted for age, sex, and race-ethnicity were used to assess the effects of APOE (ε4+ vs. ε4-) and BDNF (Met+ vs. Met-) on cognitive functioning. ANCOVAs revealed no significant main effects of APOE or BDNF genotypes on cognitive functioning; however, there was a significant APOE-by-BDNF genotype interaction for all three cognitive composite measures (visuospatial speed: ηp2=0.055; executive functioning: ηp2=0.064; and memory: ηp2=0.068). Specifically, the ε4+/Met+ (N=8) subgroup demonstrated the poorest cognitive functioning relative to all other allele subgroups (ε4+/Met-: N=12, ε4-/Met+: N=23, and ε4-/Met-: N=35). This exploratory study is the first to show that, compared with other allele subgroups assessed, veterans with both ε4 and Met alleles demonstrated the poorest cognitive functioning across several cognitive domains known to be negatively affected in the context of mTBI. Further research with larger sample sizes is needed to replicate these findings.

7,8‑dihydroxyflavone reduces lipid peroxidation, proinflammatory cytokines, and mediators in chemically induced‑phenylketonuria model.

Phenylketonuria (PKU) stems from a rare genetic metabolic imbalance attributed to an insufficiency in the enzyme phenylalanine hydroxylase. Within the context of PKU, brain‑derived neurotrophic factor (BDNF) plays a pivotal role in brain function. 7,8‑dihydroxyflavone (7,8‑DHF) operates as a tropomyosin receptor kinase B (TrkB) agonist, mimicking the effects of BDNF. This study aimed to examine the effects of administering 7,8‑DHF in chemically‑induced rat models specifically induced to simulate PKU chemically. The rats were subcutaneously injected with phenylalanine and p‑chlorophenylalanine, a phenylalanine hydroxylase inhibitor, along with 7,8‑DHF. The injections began on the 2nd day after birth and continued until the 10th day. Levels of interleukin‑1β (IL‑1β), interleukin‑6 (IL‑6), interleukin‑33 (IL‑33), BDNF, malondialdehyde (MDA), monoamine oxidase (MAO), and superoxide dismutase (SOD) in the brain tissues were quantified using the enzyme‑linked immunosorbent assay (ELISA). Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) was performed to assess the gene expressions of inducible nitric oxide synthase (iNOS), nuclear factor kappa beta (NF‑κB), caspase‑3, nuclear factor erythroid 2‑related factor 2 (Nrf2), heme oxygenase‑1 (HO‑1), and BDNF. The results showed a decrease in mRNA levels of iNOS, IL‑1β, IL‑6, and lipid peroxidation in the group that received 7,8‑DHF. These results indicate that administering 7,8‑DHF has the potential to reduce brain damage in PKU by lowering proinflammatory cytokine levels and lipid peroxidation in PKU models. Thus, 7,8‑DHF, as a small molecule, might offer a promising adjunct therapeutic approach for PKU.

Visual stimulation and brain-derived neurotrophic factor (BDNF) have protective effects in experimental autoimmune uveoretinitis

AimsTo investigate the therapeutic potential of visual stimulation (VS) and BDNF in murine experimental autoimmune uveoretinitis (EAU). Main methodsMice were immunized by subcutaneous injection of interphotoreceptor retinoid-binding protein in Freund's complete adjuvant and intravenous injection of pertussis toxin, and were then exposed to high-contrast VS 12 h/day (days 1–14 post-immunization). EAU severity was assessed by examining clinical score, visual acuity, inflammatory markers, and immune cells in the retina. The transcriptome of activated retinal cells was determined by RNA-seq using RNA immunoprecipitated in complex with phosphorylated ribosomal protein S6. The retinal levels of protein products of relevant upregulated genes were quantified. The effect of BDNF on EAU was tested in unstimulated mice by its daily topical ocular administration (days 8–14 post-immunization). Key findingsVS attenuated EAU development and decreased the expression of pro-inflammatory cytokines/chemokines and numbers of immune cells in the retina (n = 10–20 eyes/group for each analysis). In activated retinal cells of control mice (n = 30 eyes/group), VS upregulated genes encoding immunomodulatory neuropeptides, of which BDNF and vasoactive intestinal peptide (VIP) also showed increased mRNA and protein levels in the retina of VS-treated EAU mice (n = 6–10 eyes/group for each analysis). In unstimulated EAU mice, BDNF treatment mimicked the protective effects of VS by modulating the inflammatory and stem cell properties of Müller cells (n = 5 eyes/group for each analysis). SignificanceVS effectively suppresses EAU, at least through enhancing retinal levels of anti-inflammatory and neuroprotective factors, VIP and BDNF. Our findings also suggest BDNF as a promising therapeutic agent for uveitis treatment.

BDNF Modulation by microRNAs: An Update on the Experimental Evidence.

MicroRNAs can interfere with protein function by suppressing their messenger RNA translation or the synthesis of its related factors. The function of brain-derived neurotrophic factor (BDNF) is essential to the proper formation and function of the nervous system and is seen to be regulated by many microRNAs. However, understanding how microRNAs influence BDNF actions within cells requires a wider comprehension of their integrative regulatory mechanisms. Aim: In this literature review, we have synthesized the evidence of microRNA regulation on BDNF in cells and tissues, and provided an analytical discussion about direct and indirect mechanisms that appeared to be involved in BDNF regulation by microRNAs. Methods: Searches were conducted on PubMed.gov using the terms "BDNF" AND "MicroRNA" and "brain-derived neurotrophic factor" AND "MicroRNA", updated on 1 September 2023. Papers without open access were requested from the authors. One hundred and seventy-one papers were included for review and discussion. Results and Discussion: The local regulation of BDNF by microRNAs involves a complex interaction between a series of microRNAs with target proteins that can either inhibit or enhance BDNF expression, at the core of cell metabolism. Therefore, understanding this homeostatic balance provides resources for the future development of vector-delivery-based therapies for the neuroprotective effects of BDNF.

NRN1 epistasis with BDNF and CACNA1C: mediation effects on symptom severity through neuroanatomical changes in schizophrenia

The expression of Neuritin-1 (NRN1), a neurotrophic factor crucial for neurodevelopment and synaptic plasticity, is enhanced by the Brain Derived Neurotrophic Factor (BDNF). Although the receptor of NRN1 remains unclear, it is suggested that NRN1’s activation of the insulin receptor (IR) pathway promotes the transcription of the calcium voltage-gated channel subunit alpha1 C (CACNA1C). These three genes have been independently associated with schizophrenia (SZ) risk, symptomatology, and brain differences. However, research on how they synergistically modulate these phenotypes is scarce. We aimed to study whether the genetic epistasis between these genes affects the risk and clinical presentation of the disorder via its effect on brain structure. First, we tested the epistatic effect of NRN1 and BDNF or CACNA1C on (i) the risk for SZ, (ii) clinical symptoms severity and functionality (onset, PANSS, CGI and GAF), and (iii) brain cortical structure (thickness, surface area and volume measures estimated using FreeSurfer) in a sample of 86 SZ patients and 89 healthy subjects. Second, we explored whether those brain clusters influenced by epistatic effects mediate the clinical profiles. Although we did not find a direct epistatic impact on the risk, our data unveiled significant effects on the disorder’s clinical presentation. Specifically, the NRN1-rs10484320 x BDNF-rs6265 interplay influenced PANSS general psychopathology, and the NRN1-rs4960155 x CACNA1C-rs1006737 interaction affected GAF scores. Moreover, several interactions between NRN1 SNPs and BDNF-rs6265 significantly influenced the surface area and cortical volume of the frontal, parietal, and temporal brain regions within patients. The NRN1-rs10484320 x BDNF-rs6265 epistasis in the left lateral orbitofrontal cortex fully mediated the effect on PANSS general psychopathology. Our study not only adds clinical significance to the well-described molecular relationship between NRN1 and BDNF but also underscores the utility of deconstructing SZ into biologically validated brain-imaging markers to explore their mediation role in the path from genetics to complex clinical manifestation.

Brain neurotrophic factor BDNF: new data, functions and questions

The brain-derived neurotrophic factor (BDNF) is a key modulator of neurogenesis, synaptogenesis, neuroregeneration, and cell differentiation in the nervous system. Impaired BDNF functioning is a characteristic of various neurological diseases, such as Alzheimer’s disease, multiple sclerosis, and depressive disorders. There is recent evidence that patients with COVID-19 have reduced BDNF levels in the blood plasma. Furthermore, exogenous BDNF and its mimetics have demonstrated therapeutic potential.
 In this review, we systematized data of the BDNF gene structure, epigenetic and microRNA-mediated regulation of its expression, transcriptional variants of BDNF, and the effects of BDNF on neuronal and oligodendroglial differentiation. Further, we point out the gaps in the current knowledge about BDNF and propose experiments that can expand such knowledge and the range of possibilities for using BDNF in biomedicine. These include determining the expression pattern of all BDNF gene transcripts at different stages of differentiation and in different cell subpopulations and studying the role of receptor-independent BDNF signaling, circadian fluctuations in BDNF levels, and their role in physiological and pathophysiological conditions. Finally, for translational medicine, evaluating the effect of BDNF mimetics (including those immobilized on three-dimensional scaffolds for tissue engineering) on neuronal and oligodendroglial differentiation of pluripotent and polypotent cells and identifying molecular regulators of BDNF transcription, including small molecules and microRNAs capable of regulating BDNF gene expression, are crucial.

Brain-Derived Neurotrophic Factor (BDNF) Enhances Osteogenesis and May Improve Bone Microarchitecture in an Ovariectomized Rat Model.

Brain-derived neurotrophic factor (BDNF) has gained attention as a therapeutic agent due to its potential biological activities, including osteogenesis. However, the molecular mechanisms involved in the osteogenic activity of BDNF have not been fully understood. This study aimed to investigate the action of BDNF on the osteoblast differentiation in bone marrow stromal cells, and its influence on signaling pathways. In addition, to evaluate the clinical efficacy, an in vivo animal study was performed. Preosteoblast cells (MC3T3-E1), bone marrow-derived stromal cells (ST2), and a direct 2D co-culture system were treated with BDNF. The effect of BDNF on cell proliferation was determined using the CCK-8 assay. Osteoblast differentiation was assessed based on alkaline phosphatase (ALP) activity and staining and the protein expression of multiple osteoblast markers. Calcium accumulation was examined by Alizarin red S staining. For the animal study, we used ovariectomized Sprague-Dawley rats and divided them into BDNF and normal saline injection groups. MicroCT, hematoxylin and eosin (H&E), and tartrate-resistant acid phosphatase (TRAP) stain were performed for analysis. BDNF significantly increased ALP activity, calcium deposition, and the expression of osteoblast differentiation-related proteins, such as ALP, osteopontin, etc., in both ST-2 and the MC3T3-E1 and ST-2 co-culture systems. Moreover, the effect of BDNF on osteogenic differentiation was diminished by blocking tropomyosin receptor kinase B, as well as inhibiting c-Jun N-terminal kinase and p38 MAPK signals. Although the animal study results including bone density and histology showed increased osteoblastic and decreased osteoclastic activity, only a portion of parameters reached statistical significance. Our study results showed that BDNF affects osteoblast differentiation through TrkB receptor, and JNK and p38 MAPK signal pathways. Although not statistically significant, the trend of such effects was observed in the animal experiment.

YTHDF2 as a Mediator in BDNF-Induced Proliferation of Porcine Follicular Granulosa Cells.

In female mammals, the proliferation and apoptosis of granulosa cells (GCs) are critical in determining the fate of follicles and are influenced by various factors, including brain-derived neurotrophic factor (BDNF). Previous research has shown that BDNF primarily regulates GC proliferation through the PI3K/AKT, NF-kB, and CREB tumour pathways; however, the role of other molecular mechanisms in mediating BDNF-induced GC proliferation remains unclear. In this study, we investigated the involvement of the m6A reader YTH domain-containing family member 2 (YTHDF2) in BDNF-stimulated GC proliferation and its underlying mechanism. GCs were cultured in DMEM medium supplemented with varying BDNF concentrations (0, 10, 30, 75, and 150 ng/mL) for 24 h. The viability, number, and cell cycle of GCs were assessed using the CCK-8 assay, cell counting, and flow cytometry, respectively. Further exploration into YTHDF2's role in BDNF-stimulated GC proliferation was conducted using RT-qPCR, Western blotting, and sequencing. Our findings indicate that YTHDF2 mediates the effect of BDNF on GC proliferation. Additionally, this study suggests for the first time that BDNF promotes YTHDF2 expression by increasing the phosphorylation level of the ERK1/2 signalling pathway. This study offers a new perspective and foundation for further elucidating the mechanism by which BDNF regulates GC proliferation.

BDNF specifically expressed in hippocampal neurons is involved in methylmercury neurotoxicity resistance.

Methylmercury (MeHg) causes selective neuronal damage to cerebrocortical neurons (CCNs) in the central nervous system, but not to hippocampal neurons (HiNs), which are highly vulnerable to neurodegenerative diseases. In our previous study using cultured rat neurons, we performed a comprehensive gene expression analysis and found that the brain-derived neurotrophic factor (BDNF), a neurotrophin (NT), was specifically expressed in HiNs. Therefore, to elucidate the causal factors of MeHg toxicity resistance in HiNs, we conducted a comparative study of the protein expression and function of several NTs, including BDNF, using CCNs showing vulnerability to MeHg toxicity and HiNs showing resistance. BDNF was specifically expressed in HiNs, whereas nerve growth factor was barely detectable in either neuron type. In addition, other NTs, NT3 and NT4/5, were expressed in small but nearly equal amounts in both neuron types. Furthermore, among the various pathways involved in MeHg neurotoxicity, the p44/42 MAPK pathway was specifically activated in HiNs, even without MeHg treatment. siRNAs were used to reduce NTs in both neuron types. Only a specific reduction in BDNF attenuated the resistance to MeHg toxicity and p44/42 MAPK activation in HiNs. In addition, the external addition of BDNF and NT4/5, which act on the same tyrosine receptor kinase (Trk), TrkB, suppressed MeHg neurotoxicity in both neuron types. These results suggest that BDNF, expressed specifically in HiNs, is involved in the resistance to MeHg neurotoxicity via TrkB. Additionally, the activation of the p44/42 MAPK pathway may contribute to the inhibitory effect of BDNF on MeHg neurotoxicity.

Brain-derived neurotrophic factor from microglia regulates neuronal development in the medial prefrontal cortex and its associated social behavior

Microglia and brain-derived neurotrophic factor (BDNF) are essential for the neuroplasticity that characterizes critical developmental periods. The experience-dependent development of social behaviors—associated with the medial prefrontal cortex (mPFC)—has a critical period during the juvenile period in mice. However, whether microglia and BDNF affect social development remains unclear. Herein, we aimed to elucidate the effects of microglia-derived BDNF on social behaviors and mPFC development. Mice that underwent social isolation during p21–p35 had increased Bdnf in the microglia accompanied by reduced adulthood sociability. Additionally, transgenic mice overexpressing microglial Bdnf—regulated using doxycycline at different time points—underwent behavioral, electrophysiological, and gene expression analyses. In these mice, long-term overexpression of microglial BDNF impaired sociability and excessive mPFC inhibitory neuronal circuit activity. However, administering doxycycline to normalize BDNF from p21 normalized sociability and electrophysiological function in the mPFC, whereas normalizing BDNF from later ages (p45–p50) did not normalize electrophysiological abnormalities in the mPFC, despite the improved sociability. To evaluate the possible role of BDNF in human sociability, we analyzed the relationship between adverse childhood experiences and BDNF expression in human macrophages, a possible proxy for microglia. Results show that adverse childhood experiences positively correlated with BDNF expression in M2 but not M1 macrophages. In summary, our study demonstrated the influence of microglial BDNF on the development of experience-dependent social behaviors in mice, emphasizing its specific impact on the maturation of mPFC function, particularly during the juvenile period. Furthermore, our results propose a translational implication by suggesting a potential link between BDNF secretion from macrophages and childhood experiences in humans.

High-Serum Brain-Derived Neurotrophic Factor Levels Are Associated With Decreased Risk of Poststroke Cognitive Impairment.

BDNF (brain-derived neurotrophic factor) is widely implicated in the pathophysiological process of stroke, but the effect of BDNF on poststroke cognitive impairment (PSCI) remains unclear. We aimed to investigate the association between baseline serum BDNF and the risk of PSCI at 3 months in a multicenter study based on a preplanned ancillary study of the CATIS trial (China Antihypertensive Trial in Acute Ischemic Stroke). We examined serum BDNF levels at baseline and used the Mini-Mental State Examination and Montreal Cognitive Assessment to evaluate cognitive function at 3-month follow-up after ischemic stroke. PSCI was defined as Mini-Mental State Examination score <27 or Montreal Cognitive Assessment score <25. Logistic regression analyses were performed to evaluate the association between serum BDNF and the risk of 3-month PSCI. In this ancillary study, a total of 660 patients with ischemic stroke with hypertension were included, and 593 patients (mean age, 59.90±10.44 years; 410 males and 183 females) were finally included in this analysis. According to mini-mental state examination score, after adjustment for age, sex, education, baseline National Institutes of Health Stroke Scale score, APOE ɛ4 carriers, and other potential confounders, the odds ratio of PSCI for the highest tertile of BDNF was 0.60 ([95% CI, 0.39-0.94]; P=0.024) compared with the lowest tertile. Multiple-adjusted spline regression model showed a linear association of serum BDNF levels with PSCI at 3 months (P value for linearity=0.010). Adding serum BDNF to conventional prognostic factors slightly improved the risk reclassification of PSCI (net reclassification improvement: 27.46%, P=0.001; integrated discrimination index: 1.02%, P=0.015). Similar significant findings were observed when PSCI was defined by the Montreal Cognitive Assessment score. Elevated serum BDNF levels were associated with a decreased risk of PSCI at 3 months, suggesting that serum BDNF might be a potential predictive biomarker for PSCI among patients with ischemic stroke with hypertension.

The relevance of BDNF for neuroprotection and neuroplasticity in multiple sclerosis.

Neuroplasticity as a mechanism to overcome central nervous system injury resulting from different neurological diseases has gained increasing attention in recent years. However, deficiency of these repair mechanisms leads to the accumulation of neuronal damage and therefore long-term disability. To date, the mechanisms by which remyelination occurs and why the extent of remyelination differs interindividually between multiple sclerosis patients regardless of the disease course are unclear. A member of the neurotrophins family, the brain-derived neurotrophic factor (BDNF) has received particular attention in this context as it is thought to play a central role in remyelination and thus neuroplasticity, neuroprotection, and memory. To analyse the current literature regarding BDNF in different areas of multiple sclerosis and to provide an overview of the current state of knowledge in this field. To date, studies assessing the role of BDNF in patients with multiple sclerosis remain inconclusive. However, there is emerging evidence for a beneficial effect of BDNF in multiple sclerosis, as studies reporting positive effects on clinical as well as MRI characteristics outweighed studies assuming detrimental effects of BDNF. Furthermore, studies regarding the Val66Met polymorphism have not conclusively determined whether this is a protective or harmful factor in multiple sclerosis, but again most studies hypothesized a protective effect through modulation of BDNF secretion and anti-inflammatory effects with different effects in healthy controls and patients with multiple sclerosis, possibly due to the pro-inflammatory milieu in patients with multiple sclerosis. Further studies with larger cohorts and longitudinal follow-ups are needed to improve our understanding of the effects of BDNF in the central nervous system, especially in the context of multiple sclerosis.

Positive Effects of Adiponectin, BDNF, and GLP-1 on Cortical Neurons Counteracting Palmitic Acid Induced Neurotoxicity.

The prevalence of metabolic syndrome caused by diets containing excessive fatty acids is increasing worldwide. Patients with metabolic syndrome exhibit abnormal lipid profiles, chronic inflammation, increased levels of saturated fatty acids, impaired insulin sensitivity, excessive fat accumulation, and neuropathological issues such as memory deficits. In particular, palmitic acid (PA) in saturated fatty acids aggravates inflammation, insulin resistance, impaired glucose tolerance, and synaptic failure. Recently, adiponectin, brain-derived neurotrophic factor (BDNF), and glucose-like peptide-1 (GLP-1) have been investigated to find therapeutic solutions for metabolic syndrome, with findings suggesting that they are involved in insulin sensitivity, enhanced lipid profiles, increased neuronal survival, and improved synaptic plasticity. We investigated the effects of adiponectin, BDNF, and GLP-1 on neurite outgrowth, length, and complexity in PA-treated primary cortical neurons using Sholl analysis. Our findings demonstrate the therapeutic potential of adiponectin, BDNF, and GLP-1 in enhancing synaptic plasticity within brains affected by metabolic imbalance. We underscore the need for additional research into the mechanisms by which adiponectin, BDNF, and GLP-1 influence neural complexity in brains with metabolic imbalances.

The effect of brain-derived neurotrophic factor (BDNF) on food consumption of broilers: Role of serotonergic receptors

Previously, the effects of brain-derived neurotrophic factor (BDNF) on feed intake of mammals were studied, however, its role in avian feeding regulation remains unclear. Therefore, the present study aimed to investigate the possible effects of BDNF on the food consumption of broilers and its interaction with the serotonergic system. In the first treatment, broilers received intracerebroventricular (ICV) infusion of BDNF (7.5, 15, and 30 μg). BDNF (30 μg), Fluoxetine (10 μg), a serotonin reuptake inhibitor, and BDNF + Fluoxetine were injected in the second treatment. In subsequent treatments, instead of Fluoxetine, PCPA (serotonin synthesis inhibitor, 1.25 μg), SB242084 (antagonist of 5-HT2C receptor, 1.5 µg), and 8-OH-DPAT (agonist of 5-HT1A receptor, 15.25 nmol) were applied. Then, total food intake was recorded for 2 hours. According to the results, BDNF injection (15 and 30 μg) caused a significant decrease in the food intake of broilers compared to the control group (P&lt;0.05). Simultaneous administration of PCPA and SB242084 with BDNF suppressed BDNF-induced hypophagia (P&lt;0.05), while the injection of fluoxetine + BDNF strengthened this hypophagic effect (P&lt;0.05). The decrease in feed intake caused by BDNF was not significantly changed by simultaneous injection of BDNF + 8-OH-DPAT (P≥0.05). According to the findings, it seems that BDNF reduces food consumption in broilers and this effect is probably mediated via 5-HT2c receptors.

Brain‐derived neurotrophic factor alleviates clinical symptoms of experimental autoimmune uveoretinitis and supports retinal regeneration

Purpose: Brain‐derived neurotrophic factor (BDNF) is one of the most important neurotrophins that has a fundamental role in the regulation of neuronal growth, proliferation, and regeneration, as well as an important modulatory effect on the immune cells. In addition, BDNF potentiates the neurodifferentiation of Müller cells (MCs), thus supporting retinal regeneration. Therefore, we aimed to investigate the anti‐inflammatory effect of BDNF in experimental autoimmune uveoretinitis (EAU), a severe neuroinflammatory condition, and whether BDNF could facilitate the regenerative capacity of MCs in EAU.Methods: EAU in mice was induced by s.c. administration of retinal antigen IRBP1‐20 emulsified in a complete Freud's adjuvant, followed by i.v. administration of Pertussis toxin. BDNF was administered daily in the form of eye drops from day 8 to day 14 after immunization. On day 14, fundoscopy was performed to assess clinical signs of EAU. Mice were then euthanized, and their eyes and retinas were isolated for further Western blot, RT‐qPCR, flow cytometry, and immunohistochemistry analyses.Results: The treatment with BDNF significantly improved the clinical manifestations of EAU, including optic disc oedema, vasculitis, and inflammatory infiltrates in the retina. BDNF significantly decreased the infiltration of CD4+ T cells, CD8+ T cells, and CD11b+ myeloid cells into the retina and also suppressed the expression of several pro‐inflammatory cytokines and chemokines. In addition, BDNF administration significantly increased the expression of markers of neurogenesis in retinal MCs.Conclusions: Together, our results demonstrate that BDNF has important anti‐inflammatory and neurogenic properties and that it may serve as a promising target for developing novel therapeutic strategies for neurodegenerative and neuroinflammatory diseases of the retina.Support.This study was supported by the following grant projects: GAUK 378421, 260 648/SVV/2023, and COOPERATIO Neurosciences.

Differential contribution of TrkB and p75NTR to BDNF-dependent self-renewal, proliferation, and differentiation of adult neural stem cells.

Alterations in adult neurogenesis are a common hallmark of neurodegenerative diseases. Therefore, understanding the molecular mechanisms that control this process is an indispensable requirement for designing therapeutic interventions addressing neurodegeneration. Neurotrophins have been implicated in multiple functions including proliferation, survival, and differentiation of the neural stem cells (NSCs), thereby being good candidates for therapeutic intervention. Brain-derived neurotrophic factor (BDNF) belongs to the neurotrophin family and has been proven to promote neurogenesis in the subgranular zone. However, the effects of BDNF in the adult subventricular zone (SVZ) still remain unclear due to contradictory results. Using in vitro cultures of adult NSCs isolated from the mouse SVZ, we show that low concentrations of BDNF are able to promote self-renewal and proliferation in these cells by activating the tropomyosin-related kinase B (TrkB) receptor. However, higher concentrations of BDNF that can bind the p75 neurotrophin receptor (p75NTR) potentiate TrkB-dependent self-renewal and proliferation and promote differentiation of the adult NSCs, suggesting different molecular mechanisms in BDNF-promoting proliferation and differentiation. The use of an antagonist for p75NTR reduces the increment in NSC proliferation and commitment to the oligodendrocyte lineage. Our data support a fundamental role for both receptors, TrkB and p75NTR, in the regulation of NSC behavior.

Brain-derived neurotrophic factor (BDNF) downregulates mRNA levels of suppressor of cancer cell invasion (SCAI) variants in cortical neurons.

Suppressor of cancer cell invasion (SCAI) acts as a transcriptional repressor of serum response factor (SRF)-mediated gene expression by binding to megakaryoblastic leukemia (MKL)/myocardin-related transcription factor (MRTF), which is an SRF transcriptional coactivator. Growing evidence suggests that SCAI is a negative regulator of neuronal morphology, whereas MKL2/MRTFB is a positive regulator. The mRNA expression of SCAI is downregulated during brain development, suggesting that a reduction in SCAI contributes to the reduced suppression of SRF-mediated gene induction, thus increasing dendritic complexity and developing neuronal circuits. In the present study, we hypothesized that brain-derived neurotrophic factor (BDNF), which is important for neuronal plasticity and development, might alter SCAI mRNA levels. We therefore investigated the effects of BDNF on SCAI mRNA levels in primary cultured cortical neurons. Furthermore, because alternative splicing generates several SCAI variants in the brain, we measured SCAI variant mRNA after BDNF stimulation. Both SCAI variant 1 and total SCAI mRNA expression levels were downregulated by BDNF. Moreover, the extracellular signal-regulated protein kinase/mitogen-activated protein kinase (ERK/MAPK) pathway was involved in the BDNF-mediated decrease in SCAI mRNA expression. Our findings provide insights into the molecular mechanism underlying a neurotrophic factor switch for the repressive transcriptional complex that includes SCAI.

Brain-derived neurotrophic factor (BDNF) activates PI3K-AKT-mTOR signaling via hypothalamic TrkB receptors to reduce feeding in Siberian sturgeon (Acipenser baerii)

Although Brain-derived neurotrophic factor (BDNF) has been identified as an orexigenic peptide in zebrafish, its role in regulating feeding behavior in other fish species is still unclear. This study aimed to investigate the regulatory role of BDNF in feeding behavior of Siberian sturgeon (Acipenser baerii). The bdnf and its receptor TrkB genes (Abbdnf and AbTrkB) of Siberian sturgeon were cloned and found to be most highly expressed in the hypothalamus. Short- and long-term fasting experiments showed that Abbdnf and AbTrkB mRNA levels decreased in the hypothalamus after fasting, but increased after refeeding, consistent with the pattern observed for anorexigenic peptides. The NGF(nerve growth factor) structural domain has an important role in mediating the binding of BDNF to the TrkB receptor. To explore the feeding regulatory role of BDNF, recombinant AbBDNFNGF protein was expressed using prokaryotic expression system. Intraperitoneal injection of AbBDNFNGF suppressed cumulative food intake at 1 h, 3 h, and 6 h after administration, and resulted in upregulation of anorexigenic peptides (pomc and leptin) mRNA and downregulation of orexigenic peptides (npy and agrp) mRNA in both central and peripheral tissues. Additionally, AbBDNFNGF injection led to activation of TrkB receptors and pi3k-akt-mtor signaling pathway in the hypothalamus. Overall, this study confirms the anorexigenic effect of BDNF in Siberian sturgeon.

Brain-derived neurotrophic factor protects neurons by stimulating mitochondrial function through protein kinase A.

Brain-derived neurotrophic factor (BDNF) stimulates dendrite outgrowth and synaptic plasticity by activating downstream protein kinase A (PKA) signaling. Recently, BDNF has been shown to modulate mitochondrial respiration in isolated brain mitochondria, suggesting that BDNF can modulate mitochondrial physiology. However, the molecular mechanisms by which BDNF stimulates mitochondrial function in neurons remain to be elucidated. In this study, we surmised that BDNF binds to the TrkB receptor and translocates to mitochondria to govern mitochondrial physiology in a PKA-dependent manner. Confocal microscopy and biochemical subcellular fractionation assays confirm the localization of the TrkB receptor in mitochondria. The translocation of the TrkB receptor to mitochondria was significantly enhanced upon treating primary cortical neurons with exogenous BDNF, leading to rapid PKA activation. Showing a direct role of BDNF in regulating mitochondrial structure/function, time-lapse confocal microscopy in primary cortical neurons showed that exogenous BDNF enhances mitochondrial fusion, anterograde mitochondrial trafficking, and mitochondrial content within dendrites, which led to increased basal and ATP-linked mitochondrial respiration and glycolysis as assessed by an XF24e metabolic analyzer. BDNF-mediated regulation of mitochondrial structure/function requires PKA activity as treating primary cortical neurons with a pharmacological inhibitor of PKA or transiently expressing constructs that target an inhibitor peptide of PKA (PKI) to the mitochondrion abrogated BDNF-mediated mitochondrial fusion and trafficking. Mechanistically, western/Phos-tag blots show that BDNF stimulates PKA-mediated phosphorylation of Drp1 and Miro-2 to promote mitochondrial fusion and elevate mitochondrial content in dendrites, respectively. Effects of BDNF on mitochondrial function were associated with increased resistance of neurons to oxidative stress and dendrite retraction induced by rotenone. Overall, this study revealed new mechanisms of BDNF-mediated neuroprotection, which entails enhancing mitochondrial health and function of neurons.

The effect of omega 3 supplementation on serum brain-derived neurotrophic factor: A systematic review and meta-analysis

The brain-derived neurotrophic factor (BDNF) is crucial for the metabolic and mental health of an individual. Numerous intervention experiments with the goal of increasing BDNF levels have been conducted as a result of the fact that higher concentrations are linked to better cognitive function. In order to obtain a better viewpoint from them, this study was conducted as the first study in this field, with the aim of comprehensively investigating the effects of omega-3 supplementation on BDNF. Scopus, PubMed/Medline, Web of Science, and Embase databases or platform were searched using standard keywords to identify all controlled trials investigating the BDNF effects of omega 3 supplementation. Pooled weighted mean difference and 95% confidence intervals were achieved by random-effects model analysis for the best estimation of outcomes. We used the Egger's test to determine whether there was publication bias. Eleven studies with 698 participants’ were included in this study. Results of random-effects meta-analysis indicated that BDNF levels were significantly increased after supplementation with omega 3 compared with the control group (pooled WMD of 1.01 μmol/L; 95% confidence interval [CI] 0.35 to 1.67; P =0.003; I2 = 97.7%) and this increase was even greater with intervention duration >10 weeks and doses ≤1500 mg/day. In addition, the effect of omega-3 supplementation on increasing glucose levels was greater in people under 50 years of age and patients with psychological diseases. In general, the present systematic review and meta‐regression analysis demonstrated that omega 3 supplementation may be able to significantly improve BDNF.