Serum mBDNF and ProBDNF Expression Levels as Diagnosis Clue for Early Stage Parkinson's Disease

BDNF/TrkB activators in Parkinson's disease: A new therapeutic strategy

Parkinson's disease (PD) is a neurodegenerative disorder of the brain and is manifested by motor and non-motor symptoms because of degenerative changes in dopaminergic neurons of the substantia nigra. PD neuropathology is associated with mitochondrial dysfunction, oxidative damage and apoptosis. Thus, the modulation of mitochondrial dysfunction, oxidative damage and apoptosis by growth factors could be a novel boulevard in the management of PD. Brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin receptor kinase type B (TrkB) are chiefly involved in PD neuropathology. BDNF promotes the survival of dopaminergic neurons in the substantia nigra and enhances the functional activity of striatal neurons. Deficiency of the TrkB receptor triggers degeneration of dopaminergic neurons and accumulation of α-Syn in the substantia nigra. As well, BDNF/TrkB signalling is reduced in the early phase of PD neuropathology. Targeting of BDNF/TrkB signalling by specific activators may attenuate PD neuropathology. Thus, this review aimed to discuss the potential role of BDNF/TrkB activators against PD. In conclusion, BDNF/TrkB signalling is decreased in PD and linked with disease severity and long-term complications. Activation of BDNF/TrkB by specific activators may attenuate PD neuropathology.

Isolation and Identification of the High-Affinity DNA Aptamer Target to the Brain-Derived Neurotrophic Factor (BDNF)

Aptamers are functional oligonucleotide ligands used for the molecular recognition of various targets. The natural characteristics of aptamers make them an excellent alternative to antibodies in diagnostics, therapeutics, and biosensing. DNA aptamers are mainly single-stranded oligonucleotides (ssDNA) that possess a definite binding to targets. However, the application of aptamers to the fields of brain health and neurodegenerative diseases has been limited to date. Herein, a DNA aptamer against the brain-derived neurotrophic factor (BDNF) protein was obtained by in vitro selection. BDNF is a potential biomarker of brain health and neurodegenerative diseases and has functions in the synaptic plasticity and survival of neurons. We identified eight aptamers that have binding affinity for BDNF from a 50-nucleotide library. Among these aptamers, NV_B12 showed the highest sensitivity and selectivity for detecting BDNF. In an aptamer-linked immobilized sorbent assay (ALISA), the NV_B12 aptamer strongly bound to BDNF protein, in a dose-dependent manner. The dissociation constant (Kd) for NV_B12 was 0.5 nM (95% CI: 0.4-0.6 nM). These findings suggest that BDNF-specific aptamers could be used as an alternative to antibodies in diagnostic and detection assays for BDNF.

Exploration of neuroprotective effect from Coriandrum sativum L. ethanolic seeds extracts on brain of obese rats

In this study, the potential neuroprotective ability of coriander seeds (Coriandrum sativum L.) ethanolic extract (CSES) as a neuroprotectant agent in the brains of high-fat diet-induced obese rats was analyzed. The study investigated how CSES impacts oxidative stress markers (i.e., malondialdehyde/MDA, glutathione/GSH and catalase), inflammation marker (i.e., Interleukin-6/IL-6), cellular senescence markers (i.e., senescence-associated β-galactoside/SA-β-Gal activity and p16), brain damage marker (i.e., Neuron-specific Enolase/NSE), and neurogenesis markers (i.e., mature Brain-derived Neurotropic Factor/BDNF, pro-BDNF, and mature/pro-BDNF ratio). Male adult Wistar rats were fed a high-fat diet and given CSES once daily, at 100 mg/kg body weight, for 12 weeks. CSES significantly reduced MDA concentration (p = < 0.001), SA-β-Gal activity (p = 0.010), and increased GSH concentration (p = 0.047) in the brain of obese rats; however, the decrease of IL-6, NSE, and p16 as well as the increase of catalase specific activity and BDNF expression were not significant. Moreover, the mature/pro-BDNF ratio was significantly higher in the brains of non-obese rats, both given the control diet and the high-fat diet compared to the control. Our results suggest that obese rats benefited from consuming CSES, showing improved oxidative stress levels, reduced cellular senescence and increased endogenous antioxidants, making CSES a potential neuroprotective agent.

Brain-derived neurotrophic factor blood levels after electroconvulsive therapy in patients with mental disorders: A systematic review and meta-analysis

OBJECTIVE

Multiple studies have indicated that electroconvulsive therapy (ECT) could increase brain-derived neurotrophic factor (BDNF) concentrations in patients with different mental disorders. The aim of this synthesis was to evaluate post-ECT BDNF concentrations in patients with various mental disorders.

METHODS

The Embase, PubMed and Web of Science databases were systematically searched for studies in English comparing BDNF concentrations before and after ECT through 11/2022. We extracted the pertinent information from the included studies and evaluated their quality. The standardized mean difference (SMD) with a 95% confidence interval (CI) was calculated to quantify BDNF concentration differences.

RESULTS

In total, 35 studies assessed BDNF concentrations in 868 and 859 patients pre and post-ECT treatment, respectively. Post-ECT-treatment BDNF concentrations were significantly higher than the pretreatment concentrations (Hedges'g = -0.50, 95% CI (-0.70, -0.30), heterogeneity I² = 74%, p < 0.001). The analysis that combined both ECT responders and non-responders demonstrated a marked increase in total BDNF levels subsequent to ECT treatment (Hedges'g = -0.27, 95% CI (-0.42, -0.11), heterogeneity I² = 40%, p = 0.0007).

CONCLUSION

Irrespective of the effectiveness of ECT, Our study shows that peripheral BDNF concentrations increase significantly after the entire course of ECT, which may enhance our comprehension of the interplay between ECT treatment and BDNF levels. However, BDNF concentrations were not associated with the effectiveness of ECT, and abnormal concentrations of BDNF may be linked to the pathophysiological process of mental illness, necessitating more future research.

Neuroprotective effect of Eugenia uniflora against intranasal MPTP-induced memory impairments in rats: The involvement of pro-BDNF/p75NTR pathway

Parkinson's disease is a multisystemic neurodegenerative disorder that includes motor and non-motor symptoms, and common symptoms include memory loss and learning difficulties. Thus, we investigated the neuroprotective potential of a hydroalcoholic extract of Brazilian purple cherry (Eugenia uniflora) (HAE-BC) on memory impairments induced by intranasal 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration in rats and the involvement of hippocampal BDNF/TrkB/p75^NTR pathway in its effects. Adult male Wistar rats were exposed to MPTP (1 mg/nostril) or vehicle. Twenty-four hours later, the HAE-BC treatments began at doses of 300 or 2000 mg/kg/day or vehicle for 14 days. From 7 days after the MPTP induction, the animals were subjected to behavioral tests to evaluate several cognitive paradigms. HAE-BC treatments, at both doses, blocked the MPTP-caused disruption in the social recognition memory, short- and long-term object recognition memories, and working memory. Furthermore, MPTP-induced motor deficit linked to striatal tyrosine hydroxylase levels decreased, which was blocked by HAE-BC. Our findings demonstrated that HAE-BC blocked the MPTP-induced increase in the hippocampal pro-BDNF, TrkB.t1, and p75^NTR levels. The pro-BDNF/p75^NTR interaction negatively regulates synaptic transmission and plasticity, and the neuroprotective effect of HAE-BC was related, at least partly, to the modulation of this hippocampal signaling pathway. Thus, our study reports the first evidence of the potential therapeutic of E. uniflora in a Parkinson's disease model in rodents.

Serum brain-derived neurotrophic factor as diagnosis clue for Alzheimer's disease: A cross-sectional observational study in the elderly

Objective

Brain-derived neurotrophic factor (BDNF) has not been validated as a diagnostic marker for Alzheimer's disease (AD). To provide a different perspective, this study aimed to evaluate the relationship between serum levels of mature BDNF (mBDNF) and precursor BDNF (proBDNF) in AD and to investigate whether serum BDNF levels or the ratio of mBDNF levels to proBDNF levels (M/P) could be a valuable biomarker for determining the risk of AD in elderly individuals.

Method

A total of 126 subjects who met the inclusion criteria were assigned to either the AD group (n = 62) or the healthy control group (HC, n = 64) in this cross-sectional observationl study. Serum levels of mBDNF and proBDNF were measured using enzyme immunoassay kits. We analyzed the Mini-Mental State Examination (MMSE) scores from the two groups and examined the associations between AD and BDNF metabolism.

Results

The serum concentration of proBDNF was significantly higher in ADs (4140.937 pg/ml) than in HCs (2606.943 pg/ml; p &lt; 0.01). The MMSE significantly correlated with proBDNF (p &lt; 0.01, r = −0.686) and M/P (p &lt; 0.01, r = 0.595) in all subjects. To determine the risk for AD, the area under the receiver operating characteristic curve was calculated, which was 0.896 (95% confidence interval 0.844–0.949) for proBDNF and 0.901 (95% 0.850–0.953) for proBDNF and M/P combined.

Conclusion

We observed a correlation between low serum proBDNF levels and higher MMSE scores in AD. The most effective diagnostic strategy was the combination of proBDNF and M/P, whereas mBDNF levels performed poorly when we evaluated the predictive model.

Development and validation of brain-derived neurotrophic factor measurement in human urine samples as a non-invasive effect biomarker

Background

Brain-derived neurotrophic factor (BDNF), a neurotrophic growth factor mainly expressed in the brain, has been proposed as a potential effect biomarker; that is, as a measurable biomarker whose values could be associated with several diseases, including neurological impairments. The European Human Biomonitoring Initiative (HBM4EU) has also recognized effect biomarkers as a useful tool for establishing link between exposure to environmental pollutants and human health. Despite the well-establish protocol for measuring serum BDNF, there is a need to validate its assessment in urine, a non-invasive sample that can be easily repeated over time. The aim of this study was to develop, standardize and validate a methodology to quantify BDNF protein levels in urine samples before its implementation in biomonitoring studies.

Methods

Different experimental conditions and non-competitive commercial enzyme-linked immunosorbent assay (ELISA) kits were tested to determine the optimal analytical procedure, trying to minimize the shortcomings of ELISA kits. The fine-tune protocol was validated in a pilot study using both upon awakening (n = 150) and prior to sleeping (n = 106) urine samples from the same Spanish adolescent males in a well-characterized study population (the Spanish INMA-Granada cohort).

Results

The best results were obtained in 0.6 ml of urine after the acidification and extraction (pre-concentration) of samples. The highest reproducibility was obtained with the ELISA kit from Raybiotech. Urinary BDNF concentrations of adolescent males were within the previously reported range (morning = 0.047-6.801 ng/ml and night = 0.047-7.404 ng/ml). Urinary BDNF levels in the awakening and pre-sleep samples did not follow a normal distribution and were not correlated.

Conclusion

The developed methodology offers good sensitivity and reproducibility. Having reliable markers in urine may facilitate both diagnosis and monitoring possible diseases (and treatment). Further studies are needed to implement urinary BDNF in biomonitoring studies to further elucidate its usefulness and biological significance for neurological impairments.

Microelectrode-Based Electrochemical Impedance Determination of Brain-Derived Neurotrophic Factor in Aqueous Humor for Diagnosis of Glaucoma

The abundance of brain-derived neurotrophic factor (BDNF) in aqueous humor (AH) is an ideal biomarker for the diagnosis of glaucoma, a chronic progressive optic neuropathy and the most frequent cause of irreversible blindness. The difficulty of AH-based BDNF detection is from the small amount of extracted AH in a paracentesis (<100 μL) and the ultra-low abundance of BDNF. In this work, we systematically studied the non-specific adsorption of biofluids on the bare gold electrode by electrochemistry and Raman spectroscopy techniques, revealing the unexpected negative correlation of the extent of non-specific adsorption with the size of the electrode. Based on it, a simple microelectrode-based sensor without the introduction of the blocking layer was developed for the detection of BDNF in the AH sample. Using electrochemical impedance spectroscopy (EIS) and extracting the changes of electron-transfer resistance of the electrochemical probe [Fe(CN)6]3-/4- on the sensor surface, the BDNF was quantified. The dynamic range was from 0.5 to 50 pg·mL-1, with a detection limit of 0.3 pg·mL-1 and a sample consumption of 5 μL. The real AH sample analysis confirmed the significant decrease of BDNF abundance in the AH of glaucoma patients. Our microelectrode-based EIS sensor displayed prominent advantages on simplified preparation, sensitive response, and low sample consumption. This AH-based BDNF analysis is expected to be used for the screening and diagnosis of glaucoma, especially for the high-risk population who have ocular diseases and have to undergo surgeries.

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

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

The role of brain derived neurotrophic factor in central nervous system

Brain derived neurotrophic factor (BDNF) has multiple biological functions which are mediated by the activation of two receptors, tropomyosin receptor kinase B (TrkB) receptor and the p75 neurotrophin receptor, involving in physiological and pathological processes throughout life. The diverse presence and activity of BDNF indicate its potential role in the pathogenesis, progression and treatment of both neurological and psychiatric disorders. This review is to provide a comprehensive assessment of the current knowledge and future directions in BDNF-associated research in the central nervous system (CNS), with an emphasis on the physiological and pathological functions of BDNF as well as its potential treatment effects in CNS diseases, including depression, Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis, multiple sclerosis, and cerebral ischemic stroke.

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.