Targeting BDNF signaling by natural products: Novel synaptic repair therapeutics for neurodegeneration and behavior disorders

Association between Higher Intake of Flavonols and Lignans and Better Mood: Evidence from Dietary and Biomarker Evaluation in Healthy Individuals

SCOPE

The aim of this study is to investigate associations between (poly)phenol consumption, circulating (poly)phenol metabolites, and mood states in healthy individuals.

METHODS AND RESULTS

The study included 333 healthy individuals. Mood state was assessed with the Positive and Negative Affect Schedule questionnaire. Dietary (poly)phenol intake was estimated  matching food consumption data collected using a Food Frequency Questionnaire(FFQ) with a comprehensive in-house (poly)phenol database. A total of 102 (poly)phenol metabolites were quantified in fasting plasma and 24 h urine samples by Liquid Chromatography-Mass Spectrometry using a validated method. A higher intake of lignans, flavanones, and flavonols estimated from FFQs was associated with positive mood after adjusting for age and sex (β: 0.118 to 0.134). A total of 11 urinary (poly)phenol metabolites, including lignan and flavonol metabolites were associated with less negative mood (β: -0.387 to -0.205). No association was found between mood and plasma (poly)phenols.

CONCLUSION

  A higher consumption of lignans flavanones and flavonols is associated with a better mood, while certain urinary metabolites are associated with less negative mood. The lack of associations between fasting plasma (poly)phenols and mood may be due to their transient nature incirculation compared with 24 h urinary metabolites, which reflect longer-term exposure.

Establishment of a high-content compatible platform to assess effects of monocyte-derived factors on neural stem cell proliferation and differentiation

During neuroinflammation, monocytes that infiltrate the central nervous system (CNS) may contribute to regenerative processes depending on their activation status. However, the extent and mechanisms of monocyte-induced CNS repair in patients with neuroinflammatory diseases remain largely unknown, partly due to the lack of a fully human assay platform that can recapitulate monocyte-neural stem cell interactions within the CNS microenvironment. We therefore developed a human model system to assess the impact of monocytic factors on neural stem cells, establishing a high-content compatible assay for screening monocyte-induced neural stem cell proliferation and differentiation. The model combined monocytes isolated from healthy donors and human embryonic stem cell derived neural stem cells and integrated both cell-intrinsic and -extrinsic properties. We identified CNS-mimicking culture media options that induced a monocytic phenotype resembling CNS infiltrating monocytes, while allowing adequate monocyte survival. Monocyte-induced proliferation, gliogenic fate and neurogenic fate of neural stem cells were affected by the conditions of monocytic priming and basal neural stem cell culture as extrinsic factors as well as the neural stem cell passage number as an intrinsic neural stem cell property. We developed a high-content compatible human in vitro assay for the integrated analysis of monocyte-derived factors on CNS repair.

BDNF and Cerebellar Ataxia

Brain-derived neurotrophic factor (BDNF) has been proposed as a treatment for neurodegeneration, including diseases of the cerebellum, where BDNF levels or those of its main receptor, TrkB, are often diminished relative to controls, thereby serving as replacement therapy. Experimental evidence indicates that BDNF signaling countered cerebellar degeneration, sensorimotor deficits, or both, in transgenic ATXN1 mice mutated for ataxin-1, Cacna1a knock-in mice mutated for ataxin-6, mice injected with lentivectors encoding RNA sequences against human FXN into the cerebellar cortex, Kcnj6Wv (Weaver) mutant mice with granule cell degeneration, and rats with olivocerebellar transaction, similar to a BDNF-overexpressing transgenic line interbred with Cacng2stg mutant mice. In this regard, this study discusses whether BDNF is effective in cerebellar pathologies where BDNF levels are normal and whether it is effective in cases with combined cerebellar and basal ganglia damage.

Oxygen metabolism abnormality and Alzheimer's disease: An update

Oxygen metabolism abnormality plays a crucial role in the pathogenesis of Alzheimer's disease (AD) via several mechanisms, including hypoxia, oxidative stress, and mitochondrial dysfunction. Hypoxia condition usually results from living in a high-altitude habitat, cardiovascular and cerebrovascular diseases, and chronic obstructive sleep apnea. Chronic hypoxia has been identified as a significant risk factor for AD, showing an aggravation of various pathological components of AD, such as amyloid β-protein (Aβ) metabolism, tau phosphorylation, mitochondrial dysfunction, and neuroinflammation. It is known that hypoxia and excessive hyperoxia can both result in oxidative stress and mitochondrial dysfunction. Oxidative stress and mitochondrial dysfunction can increase Aβ and tau phosphorylation, and Aβ and tau proteins can lead to redox imbalance, thus forming a vicious cycle and exacerbating AD pathology. Hyperbaric oxygen therapy (HBOT) is a non-invasive intervention known for its capacity to significantly enhance cerebral oxygenation levels, which can significantly attenuate Aβ aggregation, tau phosphorylation, and neuroinflammation. However, further investigation is imperative to determine the optimal oxygen pressure, duration of exposure, and frequency of HBOT sessions. In this review, we explore the prospects of oxygen metabolism in AD, with the aim of enhancing our understanding of the underlying molecular mechanisms in AD. Current research aimed at attenuating abnormalities in oxygen metabolism holds promise for providing novel therapeutic approaches for AD.

The Neurotoxic Effect of Environmental Temperature Variation in Adult Zebrafish (Danio rerio)

Neurotoxicity consists of the altered functionality of the nervous system caused by exposure to chemical agents or altered chemical-physical parameters. The neurotoxic effect can be evaluated from the molecular to the behavioural level. The zebrafish Danio rerio is a model organism used in many research fields, including ecotoxicology and neurotoxicology. Recent studies by our research group have demonstrated that the exposure of adult zebrafish to low (18 °C) or high (34 °C) temperatures alters their brain proteome and fish behaviour compared to control (26 °C). These results showed that thermal variation alters the functionality of the nervous system, suggesting a temperature-induced neurotoxic effect. To demonstrate that temperature variation can be counted among the factors that generate neurotoxicity, eight different protein datasets, previously published by our research group, were subjected to new analyses using an integrated proteomic approach by means of the Ingenuity Pathway Analysis (IPA) software (Release December 2022). The datasets consist of brain proteome analyses of wild type adult zebrafish kept at three different temperatures (18 °C, 26 °C, and 34 °C) for 4 days (acute) or 21 days (chronic treatment), and of BDNF+/- and BDNF-/- zebrafish kept at 26 °C or 34 °C for 21 days. The results (a) demonstrate that thermal alterations generate an effect that can be defined as neurotoxic (p value ≤ 0.05, activation Z score ≤ -2 or ≥2), (b) identify 16 proteins that can be used as hallmarks of the neurotoxic processes common to all the treatments applied and (c) provide three protein panels (p value ≤ 0.05) related to 18 °C, 34 °C, and BDNF depletion that can be linked to anxiety-like or boldness behaviour upon these treatments.

Temperature- and chemical-induced neurotoxicity in zebrafish

Throughout their lives, humans encounter a plethora of substances capable of inducing neurotoxic effects, including drugs, heavy metals and pesticides. Neurotoxicity manifests when exposure to these chemicals disrupts the normal functioning of the nervous system, and some neurotoxic agents have been linked to neurodegenerative pathologies such as Parkinson's and Alzheimer's disease. The growing concern surrounding the neurotoxic impacts of both naturally occurring and man-made toxic substances necessitates the identification of animal models for rapid testing across a wide spectrum of substances and concentrations, and the utilization of tools capable of detecting nervous system alterations spanning from the molecular level up to the behavioural one. Zebrafish (Danio rerio) is gaining prominence in the field of neuroscience due to its versatility. The possibility of analysing all developmental stages (embryo, larva and adult), applying the most common "omics" approaches (transcriptomics, proteomics, lipidomics, etc.) and conducting a wide range of behavioural tests makes zebrafish an excellent model for neurotoxicity studies. This review delves into the main experimental approaches adopted and the main markers analysed in neurotoxicity studies in zebrafish, showing that neurotoxic phenomena can be triggered not only by exposure to chemical substances but also by fluctuations in temperature. The findings presented here serve as a valuable resource for the study of neurotoxicity in zebrafish and define new scenarios in ecotoxicology suggesting that alterations in temperature can synergistically compound the neurotoxic effects of chemical substances, intensifying their detrimental impact on fish populations.

The neurotrophic activities of brain-derived neurotrophic factor are potentiated by binding with apigenin, a common flavone in vegetables, in stimulating the receptor signaling

AIMS

We aimed to identify the neurotrophic activities of apigenin (4',5,7-trihydroxyflavone) via its coordination with brain-derived neurotrophic factor (BNDF) and an elevated signaling of tyrosine kinase receptor B (Trk B receptor).

METHODS

The direct binding of apigenin to BDNF was validated by ultrafiltration and biacore assay. Neurogenesis, triggered by apigenin and/or BDNF, was determined in cultured SH-SY5Y cells and rat cortical neurons. The amyloid-beta (Aβ)25-35 -induced cellular stress was revealed by propidium iodide staining, mitochondrial membrane potential, bioenergetic analysis, and formation of reactive oxygen species levels. Activation of Trk B signaling was tested by western blotting.

RESULTS

Apigenin and BDNF synergistically maintained the cell viability and promoted neurite outgrowth of cultured neurons. In addition, the BDNF-induced neurogenesis of cultured neurons was markedly potentiated by applied apigenin, including the induced expressions of neurofilaments, PSD-95 and synaptotagmin. Moreover, the synergy of apigenin and BDNF alleviated the (Aβ)25-35 -induced cytotoxicity and mitochondrial dysfunction. The synergy could be accounted by phosphorylation of Trk B receptor, and which was fully blocked by a Trk inhibitor K252a.

CONCLUSION

Apigenin potentiates the neurotrophic activities of BDNF through direct binding, which may serve as a possible treatment for its curative efficiency in neurodegenerative diseases and depression.

Targeted protein degradation for the treatment of Parkinson's disease: Advances and future perspective

Parkinson's disease (PD) is a progressive disorder that belongs to a class of neurodegenerative disorders (NDs) called Synucleinopathies. It has characterized by the misfolding and aggregation of a-synuclein. Our understanding of PD continues to evolve, and so does our approach to treatment. including therapies aimed at delaying pathology, quitting neuronal loss, and shortening the course of the disease by selectively targeting essential proteins suspected to play a role in PD pathogenesis. One emerging approach that is generating significant interest is Targeted Protein Degradation (TPD). TPD is an innovative method that allows us to specifically break down certain proteins using specially designed molecules or peptides, like PROteolysis-TArgeting-Chimera (PROTACs). This approach holds great promise, particularly in the context of NDs. In this review, we will briefly explain PD and its pathogenesis, followed by discussing protein degradation systems and TPD strategy in PD by reviewing synthesized small molecules and peptides. Finally, future perspectives and challenges in the field are discussed.

Brain-Derived Neurotrophic Factor (BDNF) and Translocator Protein (TSPO) as Diagnostic Biomarkers for Acute Ischemic Stroke

Brain-derived neurotrophic factor (BDNF) interacts with tropomyosin-related kinase B (TrkB) to promote neuronal growth, survival, differentiation, neurotransmitter release, and synaptic plasticity. The translocator protein (TSPO) is known to be found in arterial plaques, which are a symptom of atherosclerosis and a contributory cause of ischemic stroke. This study aims to determine the diagnostic accuracy of plasma BDNF and TSPO levels in discriminating new-onset acute ischemic stroke (AIS) patients from individuals without acute ischemic stroke. A total of 90 AIS patients (61% male, with a mean age of 67.7 ± 12.88) were recruited consecutively in a stroke unit, and each patient was paired with two age- and gender-matched controls. The sensitivity, specificity, and area of the curve between high plasma BDNF and TSPO and having AIS was determined using receiver operating characteristic curves. Furthermore, compared to the controls, AIS patients exhibited significantly higher levels of BDNF and TSPO, blood pressure, HbA1c, and white blood cells, as well as higher creatinine levels. The plasma levels of BDNF and TSPO can significantly discriminate AIS patients from healthy individuals (AUC 0.76 and 0.89, respectively). However, combining the two biomarkers provided little improvement in AUC (0.90). It may be possible to use elevated levels of TSPO as a diagnostic biomarker in patients with acute ischemic stroke upon admission.

Antisense oligonucleotides targeting basal forebrain ATXN2 enhances spatial memory and ameliorates sleep deprivation-induced fear memory impairment in mice

INTRODUCTION

Regulation of brain-derived neurotrophic factor (BDNF) in the basal forebrain ameliorates sleep deprivation-induced fear memory impairments in rodents. Antisense oligonucleotides (ASOs) targeting ATXN2 was a potential therapy for spinocerebellar ataxia, whose pathogenic mechanism associates with reduced BDNF expression. We tested the hypothesis that ASO7 targeting ATXN2 could affect BDNF levels in mouse basal forebrain and ameliorate sleep deprivation-induced fear memory impairments.

METHODS

Adult male C57BL/6 mice were used to evaluate the effects of ASO7 targeting ATXN2 microinjected into the bilateral basal forebrain (1 μg, 0.5 μL, each side) on spatial memory, fear memory and sleep deprivation-induced fear memory impairments. Spatial memory and fear memory were detected by the Morris water maze and step-down inhibitory avoidance test, respectively. Immunohistochemistry, RT-PCR, and Western blot were used to evaluate the changes of levels of BDNF, ATXN2, and postsynaptic density 95 (PSD95) protein as well as ATXN2 mRNA. The morphological changes in neurons in the hippocampal CA1 region were detected by HE staining and Nissl staining.

RESULTS

ASO7 targeting ATXN2 microinjected into the basal forebrain could suppress ATXN2 mRNA and protein expression for more than 1 month and enhance spatial memory but not fear memory in mice. BDNF mRNA and protein expression in basal forebrain and hippocampus was increased by ASO7. Moreover, PSD95 expression and synapse formation were increased in the hippocampus. Furthermore, ASO7 microinjected into the basal forebrain increased BDNF and PSD95 protein expression in the basal forebrain of sleep-deprived mice and counteracted sleep deprivation-induced fear memory impairments.

CONCLUSION

ASOs targeting ATXN2 may provide effective interventions for sleep deprivation-induced cognitive impairments.

Adaptogens on Depression-Related Outcomes: A Systematic Integrative Review and Rationale of Synergism with Physical Activity

Depression is considered the most important disorder affecting mental health. The aim of this systematic integrative review was: (i) to describe the effects of supplementation with adaptogens on variables related to depression in adults; and (ii) to discuss the potential combination with physical exercise to aid planning and commissioning future clinical research. An integrative review was developed complementing the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement (PROSPERO registration: CRD42021249682). A total of 41 articles met the inclusion criteria. With a Price index of 46.4%, we found that: (i) Hypericum perforatum (St. John's Wort) is the most studied and supported adaptogen (17/41 [41.46%], three systematic reviews with meta-analysis) followed by Crocus sativus L. or saffron (6/41 [14.63%], three systematic reviews with meta-analysis and two systematic reviews); (ii) it is possible that the significantly better performance of adaptogens over placebo is due to the reduction of allostatic load via the action of secondary metabolites on BDNF regulation; and, (iii) the number of studies reporting physical activity levels is limited or null for those that combine an exercise program with the consumption of adaptogens. Aware of the need for a multidisciplinary approach for depression treatment, this systematic integrative review provides an up-to-date view for supporting the use of St. John's Wort and saffron as non-pharmacological strategies while also help commissioning future research on the efficacy of other adaptogens. It also contributes to the design of future clinical research studies that evaluate the consumption of herbal extracts plus physical exercise, mainly resistance training, as a potentially safe and powerful strategy to treat depression.

Ginsenoside Rg1 attenuation of neurogenesis disorder and neuronal apoptosis in the rat hippocampus after spinal cord injury may involve brain-derived neurotrophic factor/extracellular signal-regulated kinase signaling

OBJECTIVE

We previously demonstrated that spinal cord injury (SCI) induced hippocampus injury and depression in rodents. Ginsenoside Rg1 effectively prevents neurodegenerative disorders. Here, we investigated the effects of ginsenoside Rg1 on the hippocampus after SCI.

METHODS

We used a rat compression SCI model. Western blotting and morphologic assays were used to investigate the protective effects of ginsenoside Rg1 in the hippocampus.

RESULTS

Brain-derived neurotrophic factor/extracellular signal-regulated kinases (BDNF/ERK) signaling was altered in the hippocampus at 5 weeks after SCI. SCI attenuated neurogenesis and enhanced the expression of cleaved caspase-3 in the hippocampus; however, ginsenoside Rg1 attenuated cleaved caspase-3 expression and improved neurogenesis and BDNF/ERK signaling in the rat hippocampus. The results suggest that SCI affects BDNF/ERK signaling, and ginsenoside Rg1 can attenuate hippocampal damage after SCI.

CONCLUSION

We speculate that the protective effects of ginsenoside Rg1 in hippocampal pathophysiology after SCI may involve BDNF/ERK signaling. Ginsenoside Rg1 shows promise as a therapeutic pharmaceutical product when seeking to counter SCI-induced hippocampal damage.

New insights into the role of berberine against 3-nitropropionic acid-induced striatal neurotoxicity: Possible role of BDNF-TrkB-PI3K/Akt and NF-κB signaling

Berberine (Berb) is a major alkaloid with potential protective effects against multiple neurological disorders. Nevertheless, its positive effect against 3-nitropropionic acid (3NP) induced Huntington's disease (HD) modulation has not been fully elucidated. Accordingly, this study aimed to assess the possible action mechanisms of Berb against such neurotoxicity using an in vivo rats model pretreated with Berb (100 mg/kg, p.o.) alongisde 3NP (10 mg/kg, i.p.) at the latter 2 weeks to induce HD symptoms. Berb revealed its capacity to partially protect the striatum as mediated via the activation of BDNF-TrkB-PI3K/Akt signaling and amelioration of neuroinflammation status by blocking NF-κB p65 with a concomitant reduction in its downstream cytokines TNF-α and IL-1β. Moreover, its antioxidant potential was evidenced from induction of Nrf2 and GSH levels concurrent with a reduction in MDA level. Furthermore, Berb anti-apoptotic effect was manifested through the induction of pro-survival protein (Bcl-2) and down-regulation of the apoptosis biomarker (caspase-3). Finally, Berb intake ascertained its striatum protective action by improving the motor and histopathological abnormalities with concomitant dopamine restoration. In conclusion, Berb appears to modulate 3NP-induced neurotoxicity by moderating BDNF-TrkB-PI3K/Akt signaling besides its anti-inflammatory, antioxidant, as well as anti-apoptotic effect.

Dietary Protective Potential of Fucoxanthin as an Active Food Component on Neurological Disorders

The prevalence of neurodegenerative, cerebrovascular, and psychiatric diseases and other neurological disorders has increased dramatically worldwide. Fucoxanthin is an algal pigment with many biological functions, and there is rising evidence that fucoxanthin plays a preventive and therapeutic role in neurological disorders. This review focuses on the metabolism, bioavailability, and blood-brain barrier penetration of fucoxanthin. Furthermore, the neuroprotective potential of fucoxanthin in neurodegenerative diseases, cerebrovascular diseases, and psychiatric diseases as well as other neurological disorders such as epilepsy, neuropathic pain, and brain tumors by acting on multiple targets will be summarized. The multiple targets include regulating apoptosis, reducing oxidative stress, activating the autophagy pathway, inhibiting Aβ aggregation, improving dopamine secretion, reducing α-synuclein aggregation, attenuating neuroinflammation, modulating gut microbiota, and activating brain-derived neurotrophic factor, etc. Additionally, we look forward to brain-targeted oral transport systems due to the low bioavailability and blood-brain barrier permeability of fucoxanthin. We also propose exploring the systemic mechanisms of fucoxanthin metabolism and transport through the gut-brain process and envision new therapeutic targets for fucoxanthin to act on the central nervous system. Finally, we propose dietary fucoxanthin delivery interventions to achieve preventive effects on neurological disorders. This review provides a reference for the application of fucoxanthin in the neural field.

Neurotoxic and cytoprotective mechanisms in the ischemic neocortex

Neuronal damage in ischemic stroke occurs due to permanent imbalance between the metabolic needs of the brain and the ability of the blood-vascular system to maintain glucose delivery and adequate gas exchange. Oxidative stress and excitotoxicity trigger complex processes of neuroinflammation, necrosis, and apoptosis of both neurons and glial cells. This review summarizes data on the structural and chemical changes in the neocortex and main cytoprotective effects induced by focal ischemic stroke. We focus on the expression of neurotrophins (NT) and molecular and cellular changes in neurovascular units in ischemic brain. We also discuss how these factors affect the apoptosis of cortical cells. Ischemic damage involves close interaction of a wide range of signaling molecules, each acting as an efficient marker of cell state in both the ischemic core and penumbra. NTs play the main regulatory role in brain tissue recovery after ischemic injury. Heterogeneous distribution of the BDNF, NT-3, and GDNF immunoreactivity is concordant with the selective response of different types of cortical neurons and glia to ischemic injury and allows mapping the position of viable neurons. Astrocytes are the central link in neurovascular coupling in ischemic brain by providing other cells with a wide range of vasotropic factors. The NT expression coincides with the distribution of reactive astrocytes, marking the boundaries of the penumbra. The development of ischemic stroke is accompanied by a dramatic change in the distribution of GDNF reactivity. In early ischemic period, it is mainly observed in cortical neurons, while in late one, the bulk of GDNF-positive cells are various types of glia, in particular, astrocytes. The proportion of GDNF-positive astrocytes increases gradually throughout the ischemic period. Some factors that exert cytoprotective effects in early ischemic period may display neurotoxic and pro-apoptotic effects later on. The number of apoptotic cells in the ischemic brain tissue correlates with the BDNF levels, corroborating its protective effects. Cytoprotection and neuroplasticity are two lines of brain protection and recovery after ischemic stroke. NTs can be considered an important link in these processes. To develop efficient pharmacological therapy for ischemic brain injury, we have to deepen our understanding of neurochemical adaptation of brain tissue to acute stroke.

Neurotrophins and Other Growth Factors in the Pathogenesis of Alzheimer’s Disease

The involvement of the changed expression/function of neurotrophic factors in the pathogenesis of neurodegenerative diseases, including Alzheimer’s disease (AD), has been suggested. AD is one of the age-related dementias, and is characterized by cognitive impairment with decreased memory function. Developing evidence demonstrates that decreased cell survival, synaptic dysfunction, and reduced neurogenesis are involved in the pathogenesis of AD. On the other hand, it is well known that neurotrophic factors, especially brain-derived neurotrophic factor (BDNF) and its high-affinity receptor TrkB, have multiple roles in the central nervous system (CNS), including neuronal maintenance, synaptic plasticity, and neurogenesis, which are closely linked to learning and memory function. Thus, many investigations regarding therapeutic approaches to AD, and/or the screening of novel drug candidates for its treatment, focus on upregulation of the BDNF/TrkB system. Furthermore, current studies also demonstrate that GDNF, IGF1, and bFGF, which play roles in neuroprotection, are associated with AD. In this review, we introduce data demonstrating close relationships between the pathogenesis of AD, neurotrophic factors, and drug candidates, including natural compounds that upregulate the BDNF-mediated neurotrophic system.

Competing endogenous RNA (ceRNA) networks in Parkinson's disease: A systematic review

Parkinson's disease (PD) is a distinctive clinical syndrome with several causes and clinical manifestations. Aside from an infectious cause, PD is a rapidly developing neurological disorder with a global rise in frequency. Notably, improved knowledge of molecular pathways and the developing novel diagnostic methods may result in better therapy for PD patients. In this regard, the amount of research on ceRNA axes is rising, highlighting the importance of these axes in PD. CeRNAs are transcripts that cross-regulate one another via competition for shared microRNAs (miRNAs). These transcripts may be either coding RNAs (mRNAs) or non-coding RNAs (ncRNAs). This research used a systematic review to assess validated loops of ceRNA in PD. The Prisma guideline was used to conduct this systematic review, which entailed systematically examining the articles of seven databases. Out of 309 entries, forty articles met all criteria for inclusion and were summarized in the appropriate table. CeRNA axes have been described through one of the shared vital components of the axes, including lncRNAs such as NEAT1, SNHG family, HOTAIR, MALAT1, XIST, circRNAs, and lincRNAs. Understanding the multiple aspects of this regulatory structure may aid in elucidating the unknown causal causes of PD and providing innovative molecular therapeutic targets and medical fields.

Antidepressive Effect of Natural Products and Their Derivatives Targeting BDNF-TrkB in Gut-Brain Axis

Modern neurological approaches enable detailed studies on the pathophysiology and treatment of depression. An imbalance in the microbiota-gut-brain axis contributes to the pathogenesis of depression. This extensive review aimed to elucidate the antidepressive effects of brain-derived neurotrophic factor (BDNF)-targeting therapeutic natural products and their derivatives on the gut-brain axis. This information could facilitate the development of novel antidepressant drugs. BDNF is crucial for neuronal genesis, growth, differentiation, survival, plasticity, and synaptic transmission. Signaling via BDNF and its receptor tropomyosin receptor kinase B (TrkB) plays a vital role in the etiopathogenesis of depression and the therapeutic mechanism of antidepressants. This comprehensive review provides information to researchers and scientists for the identification of novel therapeutic approaches for neuropsychiatric disorders, especially depression and stress. Future research should aim to determine the possible causative role of BDNF-TrkB in the gut-brain axis in depression, which will require further animal and clinical research as well as the development of analytical approaches.

The neuroprotective effects of fisetin, a natural flavonoid in neurodegenerative diseases: Focus on the role of oxidative stress

Oxidative stress (OS) disrupts the chemical integrity of macromolecules and increases the risk of neurodegenerative diseases. Fisetin is a flavonoid that exhibits potent antioxidant properties and protects the cells against OS. We have viewed the NCBI database, PubMed, Science Direct (Elsevier), Springer-Nature, ResearchGate, and Google Scholar databases to search and collect relevant articles during the preparation of this review. The search keywords are OS, neurodegenerative diseases, fisetin, etc. High level of ROS in the brain tissue decreases ATP levels, and mitochondrial membrane potential and induces lipid peroxidation, chronic inflammation, DNA damage, and apoptosis. The subsequent results are various neuronal diseases. Fisetin is a polyphenolic compound, commonly present in dietary ingredients. The antioxidant properties of this flavonoid diminish oxidative stress, ROS production, neurotoxicity, neuro-inflammation, and neurological disorders. Moreover, it maintains the redox profiles, and mitochondrial functions and inhibits NO production. At the molecular level, fisetin regulates the activity of PI3K/Akt, Nrf2, NF-κB, protein kinase C, and MAPK pathways to prevent OS, inflammatory response, and cytotoxicity. The antioxidant properties of fisetin protect the neural cells from inflammation and apoptotic degeneration. Thus, it can be used in the prevention of neurodegenerative disorders.

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.

Oolonghomobisflavans exert neuroprotective activities in cultured neuronal cells and anti-aging effects in Caenorhabditis elegans

Potential health benefits of tea has attracted significant scientific and public attention worldwide. Tea polyphenols are considered as natural promising complementary therapeutical agents for neurodegenerative diseases. However, the anti-neurodegeneration or anti-aging activities of oolong tea polyphenols have not been investigated. The current study aims to document beneficial effects of oolong tea polyphenols [dimers of epigallocatechin gallate (EGCG), oolonghomobisflavan A (OFA), and oolonghomobisflavan B (OFB)] with neuroprotective and neuritogenesis properties in cultured neuronal (Neuro-2a and HT22) cells and Caenorhabditis elegans models. In vitro, we found that the compounds (EGCG, OFA, and OFB) protect against glutamate-induced neurotoxicity via scavenging radical activity, suppression intracellular ROS and up-regulation of antioxidant enzymes. Moreover, the compounds induce neurite outgrowth via up-regulate Ten-4 gene expression. Interestingly, OFA and OFB exert stronger neuroprotective and neurite outgrowth properties than EGCG known as an excellent antioxidant agent in tea. In vivo, we found that the compounds protect against C. elegans Aβ-induced paralysis, chemotaxis deficiency and α-synuclein aggregation. Moreover, the compounds are capable of extending the lifespan of C. elegans. OFA and OFB possess both anti-neurodegeneration and anti-aging activities, supporting its therapeutic potential for the treatment of age-related neurodegenerative diseases which need to be studied in more detail in intervention studies.

BDNF Therapeutic Mechanisms in Neuropsychiatric Disorders

Brain-derived neurotrophic factor (BDNF) is the most abundant neurotrophin in the adult brain and functions as both a primary neurotrophic signal and a neuromodulator. It serves essential roles in neuronal development, maintenance, transmission, and plasticity, thereby influencing aging, cognition, and behavior. Accumulating evidence associates reduced central and peripheral BDNF levels with various neuropsychiatric disorders, supporting its potential utilization as a biomarker of central pathologies. Subsequently, extensive research has been conducted to evaluate restoring, or otherwise augmenting, BDNF transmission as a potential therapeutic approach. Promising results were indeed observed for genetic BDNF upregulation or exogenous administration using a multitude of murine models of neurological and psychiatric diseases. However, varying mechanisms have been proposed to underlie the observed therapeutic effects, and many findings indicate the engagement of disease-specific and other non-specific mechanisms. This is because BDNF essentially affects all aspects of neuronal cellular function through tropomyosin receptor kinase B (TrkB) receptor signaling, the disruptions of which vary between brain regions across different pathologies leading to diversified consequences on cognition and behavior. Herein, we review the neurophysiology of BDNF transmission and signaling and classify the converging and diverging molecular mechanisms underlying its therapeutic potentials in neuropsychiatric disorders. These include neuroprotection, synaptic maintenance, immunomodulation, plasticity facilitation, secondary neuromodulation, and preservation of neurovascular unit integrity and cellular viability. Lastly, we discuss several findings suggesting BDNF as a common mediator of the therapeutic actions of centrally acting pharmacological agents used in the treatment of neurological and psychiatric illness.

The Role of Neurotrophin Signaling in Age-Related Cognitive Decline and Cognitive Diseases

Neurotrophins are a family of secreted proteins expressed in the peripheral nervous system and the central nervous system that support neuronal survival, synaptic plasticity, and neurogenesis. Brain-derived neurotrophic factor (BDNF) and its high affinity receptor TrkB are highly expressed in the cortical and hippocampal areas and play an essential role in learning and memory. The decline of cognitive function with aging is a major risk factor for cognitive diseases such as Alzheimer’s disease. Therefore, an alteration of BDNF/TrkB signaling with aging and/or pathological conditions has been indicated as a potential mechanism of cognitive decline. In this review, we summarize the cellular function of neurotrophin signaling and review the current evidence indicating a pathological role of neurotrophin signaling, especially of BDNF/TrkB signaling, in the cognitive decline in aging and age-related cognitive diseases. We also review the therapeutic approach for cognitive decline by the upregulation of the endogenous BDNF/TrkB-system.

Circular RNAs: Emblematic Players of Neurogenesis and Neurodegeneration

In the fascinating landscape of non-coding RNAs (ncRNAs), circular RNAs (circRNAs) are peeping out as a new promising and appreciated class of molecules with great potential as diagnostic and prognostic biomarkers. They come from circularization of single-stranded RNA molecules covalently closed and generated through alternative mRNA splicing. Dismissed for many years, similar to aberrant splicing by-products, nowadays, their role has been regained. They are able to regulate the expression of linear mRNA transcripts at different levels acting as miRNA sponges, interacting with ribonucleoproteins or exerting a control on gene expression. On the other hand, being extremely conserved across phyla and stable, cell and tissue specific, mostly abundant than the linear RNAs, it is not surprising that they should have critical biological functions. Curiously, circRNAs are particularly expressed in brain and they build up during aging and age-related diseases. These extraordinary peculiarities make circRNAs potentially suitable as promising molecular biomarkers, especially of aging and neurodegenerative diseases. This review aims to explore new evidence on circRNAs, emphasizing their role in aging and pathogenesis of major neurodegenerative disorders, Alzheimer's disease, frontotemporal dementia, and Parkinson's diseases with a look toward their potential usefulness in biomarker searching.

Brain-derived neurotrophic factor in Alzheimer's disease and its pharmaceutical potential

Synaptic abnormalities are a cardinal feature of Alzheimer's disease (AD) that are known to arise as the disease progresses. A growing body of evidence suggests that pathological alterations to neuronal circuits and synapses may provide a mechanistic link between amyloid β (Aβ) and tau pathology and thus may serve as an obligatory relay of the cognitive impairment in AD. Brain-derived neurotrophic factors (BDNFs) play an important role in maintaining synaptic plasticity in learning and memory. Considering AD as a synaptic disorder, BDNF has attracted increasing attention as a potential diagnostic biomarker and a therapeutical molecule for AD. Although depletion of BDNF has been linked with Aβ accumulation, tau phosphorylation, neuroinflammation and neuronal apoptosis, the exact mechanisms underlying the effect of impaired BDNF signaling on AD are still unknown. Here, we present an overview of how BDNF genomic structure is connected to factors that regulate BDNF signaling. We then discuss the role of BDNF in AD and the potential of BDNF-targeting therapeutics for AD.

Fisetin, potential flavonoid with multifarious targets for treating neurological disorders: An updated review

Neurodegenerative disorders pose a significant health burden and imprint a debilitative impact on the quality of life. Importantly, aging is intricately intertwined with the progression of these disorders, and their prevalence increases with a rise in the aging population worldwide. In recent times, fisetin emerged as one of the potential miracle molecules to address neurobehavioral and cognitive abnormalities. These effects were attributed to its actions on several macromolecules and multiple molecular mechanisms. Fisetin belongs to a class of flavonoids, which is found abundantly in several fruits and vegetables. Fisetin has manifested several health benefits in preclinical models of neurodegenerative diseases such as Alzheimer's disease, Vascular dementia, and Schizophrenia. Parkinson's disease, Amyotrophic Lateral Sclerosis, Huntington's disease, Stroke, Traumatic Brain Injury (TBI), and age-associated changes. This review aimed to evaluate the potential mechanisms and pharmacological effects of fisetin in treating several neurological diseases. This review also provides comprehensive data on up-to-date recent literature and highlights the various mechanistic pathways pertaining to fisetin's neuroprotective role.

Ketamine: Neuroprotective or Neurotoxic?

Ketamine, a non-competitive N-methyl-D-aspartate receptor (NMDAR) antagonist, has been employed clinically as an intravenous anesthetic since the 1970s. More recently, ketamine has received attention for its rapid antidepressant effects and is actively being explored as a treatment for a wide range of neuropsychiatric syndromes. In model systems, ketamine appears to display a combination of neurotoxic and neuroprotective properties that are context dependent. At anesthetic doses applied during neurodevelopmental windows, ketamine contributes to inflammation, autophagy, apoptosis, and enhances levels of reactive oxygen species. At the same time, subanesthetic dose ketamine is a powerful activator of multiple parallel neurotrophic signaling cascades with neuroprotective actions that are not always NMDAR-dependent. Here, we summarize results from an array of preclinical studies that highlight a complex landscape of intracellular signaling pathways modulated by ketamine and juxtapose the somewhat contrasting neuroprotective and neurotoxic features of this drug.

Modulation of Brain-Derived Neurotrophic Factor (BDNF) Signaling Pathway by Culinary Sage (Salvia officinalis L.)

Culinary sage (Salvia officinalis L.) is a common spice plant in the mint family (Lamiaceae) well known for its distinctive culinary and traditional medicinal uses. Sage tea has been used traditionally as a brain-enhancing tonic and extracts from sage have been reported to have both cognitive and memory enhancing effects. Brain-derived neurotrophic factor (BDNF) is an endogenous signaling molecule involved in cognition and memory function. In this study, activity-guided fractionation employing preparative reverse-phase high performance liquid chromatography (RP-HPLC) of culinary sage extracts led to the discovery of benzyl 6-O-β-D-apiofuranosyl-β-D-glucoside (B6AG) as a natural product that upregulates transcription of neurotrophic factors in C6 glioma cells. Purified B6AG showed a moderate dose response, with upregulation of BDNF and with EC₅₀ at 6.46 μM. To better understand the natural variation in culinary sage, B6AG was quantitated in the leaves of several commercial varieties by liquid chromatography-mass spectrometry (LC-MS). The level of B6AG in dried culinary sage was found to range from 334 ± 14 to 698 ± 65 μg/g. This study provided a foundation for future investigations, including quantitative inquiries on the distribution of B6AG within the different plant organs, explorations in optimizing post-harvest practices, and aid in the development of sage varieties with elevated levels of B6AG.

Natural Products for Neurodegeneration: Regulating Neurotrophic Signals

Neurodegenerative disorders (NDs) are heterogeneous groups of ailments typically characterized by progressive damage of the nervous system. Several drugs are used to treat NDs but they have only symptomatic benefits with various side effects. Numerous researches have been performed to prove the advantages of phytochemicals for the treatment of NDs. Furthermore, phytochemicals such as polyphenols might play a pivotal role in rescue from neurodegeneration due to their various effects as anti-inflammatory, antioxidative, and antiamyloidogenic agents by controlling apoptotic factors, neurotrophic factors (NTFs), free radical scavenging system, and mitochondrial stress. On the other hand, neurotrophins (NTs) including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT4/5, and NT3 might have a crucial neuroprotective role, and their diminution triggers the development of the NDs. Polyphenols can interfere directly with intracellular signaling molecules to alter brain activity. Several natural products also improve the biosynthesis of endogenous genes encoding antiapoptotic Bcl-2 as well as NTFs such as glial cell and brain-derived NTFs. Various epidemiological studies have demonstrated that the initiation of these genes could play an essential role in the neuroprotective function of dietary compounds. Hence, targeting NTs might represent a promising approach for the management of NDs. In this review, we focus on the natural product-mediated neurotrophic signal-modulating cascades, which are involved in the neuroprotective effects.

Ultrasound Combined With Microbubbles Loading BDNF Retrovirus to Open BloodBrain Barrier for Treatment of Alzheimer's Disease

Background: Brain-derived nerve growth factor (BDNF) is a promising effective target for the treatment of Alzheimer's disease (AD). BDNF, which has a high molecular weight, has difficulty in crossing the blood-brain barrier (BBB). The study aimed to prepare microbubbles loading brain-derived nerve growth factor (BDNF) retrovirus (MpLXSN-BDNF), to verify the characteristics of the microbubbles, and to study the therapeutic effect of the microbubbles combined with ultrasound on the opening of the blood-brain barrier in an AD rat model. Methods: 32 adult male SD rats were randomly divided into four groups: control group, ultrasound + pLXSN-EGFP microbubble group (U + MpLXSN-BDNF), ultrasound + pLXSN-BDNF microbubble group, and ultrasound + microbubble + pLXSN-BDNF virus group (U + MpLXSN-BDNF), with eight rats in each group. At the same time, the left hippocampus of rats was irradiated with low-frequency focused ultrasound guided by MRI to open the blood-brain barrier (BBB). The effects of BDNF overexpression on AD rats were evaluated behaviorally before and 1 month after the treatment. The number of acetylcholinesterase (ChAT)-positive cells and the content of acetylcholine (ACh) in brain tissues were determined by immunohistochemistry and high-performance liquid chromatography (HPLC), respectively. IF staining of synaptic spines and Western blot of synaptophysin presented herein detected synaptic density recovery. Results: Signal intensity enhancement at the BBB disruption sites could be observed on the MR images. The behavioral evaluation showed that the times of crossing the original platform in the U + MpLXSN-BDNF group increased significantly after treatment. Immunohistochemistry and HPLC revealed that the number of ChAT-positive neurons and the contents of ACh in the brain were significantly decreased in the treated groups compared with the controls. IF staining of synaptic spines and Western blot data of synaptophysin showed that the U + MpLXSN-BDNF group can recover the synaptic loss better by BDNF supplementation than the other treatment groups. Conclusion: Ultrasound combined with viral microbubbles carrying BDNF can increase the transfection efficiency of brain neurons, promote the high expression of exogenous gene BDNF, and play a therapeutic role in the AD model rats.

Dental Pulp-Derived Mesenchymal Stem Cells for Modeling Genetic Disorders

A subpopulation of mesenchymal stem cells, developmentally derived from multipotent neural crest cells that form multiple facial tissues, resides within the dental pulp of human teeth. These stem cells show high proliferative capacity in vitro and are multipotent, including adipogenic, myogenic, osteogenic, chondrogenic, and neurogenic potential. Teeth containing viable cells are harvested via minimally invasive procedures, based on various clinical diagnoses, but then usually discarded as medical waste, indicating the relatively low ethical considerations to reuse these cells for medical applications. Previous studies have demonstrated that stem cells derived from healthy subjects are an excellent source for cell-based medicine, tissue regeneration, and bioengineering. Furthermore, stem cells donated by patients affected by genetic disorders can serve as in vitro models of disease-specific genetic variants, indicating additional applications of these stem cells with high plasticity. This review discusses the benefits, limitations, and perspectives of patient-derived dental pulp stem cells as alternatives that may complement other excellent, yet incomplete stem cell models, such as induced pluripotent stem cells, together with our recent data.

Correlation of distinct behaviors to the modified expression of cerebral Shank1,3 and BDNF in two autistic animal models

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder featuring altered neuronal circuitry and consequently impaired social interactions, restrictive interests plus repetitive stereotypic activities. In the present study, differentiated behaviors of valproic (VPA) and propionic (PPA) acid-mediated autism rats were correlated to cerebral scaffolding proteins (Shank1,3) and BDNF expression variations. Sprague-Dawley offspring that received VPA during pregnancy displayed a notably diminished permanence (-78 %, p < 0.01) in the light chamber of light dark (LD) test, reduced exploratory tasks, i.e. grooming (-90 %) and rearing (-65 %). Moreover, they executed extremely greater climbing intervals (+300 %, p < 0.001) in novel cage (NC) test, plus exhibited an extremely reduced (-331 %) discrimination index in novel object recognition (NOR) test when compared to controls. PPA-treated postnatal days (PND) 12-16 rats also displayed anxiety-like behaviors, although in a less evident manner, as indicated by a moderate time (+55 %; p < 0.05) spent in dark chamber along with notable and moderate decreases in digging (-78 %) plus grooming (-52 %), respectively. Contextually, VPA- more than PPA supplied opposite Shank1,3 expression changes in cerebellum (CB; -62 %; +78 %), dorsomedial prefrontal cortex (DM-PFC; +95 % -76 %), respectively, while resulting extremely upregulated in hippocampus (HIP; +125 % - +155 %). Even BDNF resulted to be substantially and notably diminished in HIP (-85 %) and DM-PFC (-72 %), respectively, of VPA rats while it was only moderately reduced (-35 % to -45 %) in these same areas of PPA rats. The early altered brain-specific expression levels accounting for different behavioral performances may provide useful diagnostic indications and constitute valuable therapeutic strategies for autistic patients.

Dysfunction of the SNARE complex in neurological and psychiatric disorders

The communication between neurons constitutes the basis of all neural activities, and synaptic vesicle exocytosis is the fundamental biological event that mediates most communication between neurons in the central nervous system. The SNARE complex is the core component of the protein machinery that facilitates the fusion of synaptic vesicles with presynaptic terminals and thereby the release of neurotransmitters. In synapses, each release event is dependent on the assembly of the SNARE complex. In recent years, basic research on the SNARE complex has provided a clearer understanding of the mechanism underlying the formation of the SNARE complex and its role in vesicle formation. Emerging evidence indicates that abnormal expression or dysfunction of the SNARE complex in synapse physiology might contribute to abnormal neurotransmission and ultimately to synaptic dysfunction. Clinical research using postmortem tissues suggests that SNARE complex dysfunction is correlated with various neurological diseases, and some basic research has also confirmed the important role of the SNARE complex in the pathology of these diseases. Genetic and pharmacogenetic studies suggest that the SNARE complex and individual proteins might represent important molecular targets in neurological disease. In this review, we summarize the recent progress toward understanding the SNARE complex in regulating membrane fusion events and provide an update of the recent discoveries from clinical and basic research on the SNARE complex in neurodegenerative, neuropsychiatric, and neurodevelopmental diseases.

The Relation of the Brain-Derived Neurotrophic Factor with MicroRNAs in Neurodegenerative Diseases and Ischemic Stroke

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors that plays a crucial role in the development of the nervous system while supporting the survival of existing neurons and instigating neurogenesis. Altered levels of BDNF, both in the circulation and in the central nervous system (CNS), have been reported to be involved in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), multiple sclerosis (MS), and ischemic stroke. MicroRNAs (miRNAs) are a class of non-coding RNAs found in body fluids such as peripheral blood and cerebrospinal fluid. Several different miRNAs, and their target genes, are recognized to be involved in the pathophysiology of neurodegenerative and neurovascular diseases. Thus, they present as promising biomarkers and a novel treatment approach for CNS disorders. Currently, limited studies provide viable evidence of miRNA-mediated post-transcriptional regulation of BDNF. The aim of this review is to provide a comprehensive assessment of the current knowledge regarding the potential diagnostic and prognostic values of miRNAs affecting BDNF expression and its role as a CNS disorders and neurovascular disease biomarker. Moreover, a novel therapeutic approach in neurodegenerative diseases and ischemic stroke targeting miRNAs associated with BDNF will be discussed.

Competing Endogenous RNA Networks as Biomarkers in Neurodegenerative Diseases

Protein aggregation is classically considered the main cause of neuronal death in neurodegenerative diseases (NDDs). However, increasing evidence suggests that alteration of RNA metabolism is a key factor in the etiopathogenesis of these complex disorders. Non-coding RNAs are the major contributor to the human transcriptome and are particularly abundant in the central nervous system, where they have been proposed to be involved in the onset and development of NDDs. Interestingly, some ncRNAs (such as lncRNAs, circRNAs and pseudogenes) share a common functionality in their ability to regulate gene expression by modulating miRNAs in a phenomenon known as the competing endogenous RNA mechanism. Moreover, ncRNAs are found in body fluids where their presence and concentration could serve as potential non-invasive biomarkers of NDDs. In this review, we summarize the ceRNA networks described in Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis and spinocerebellar ataxia type 7, and discuss their potential as biomarkers of these NDDs. Although numerous studies have been carried out, further research is needed to validate these complex interactions between RNAs and the alterations in RNA editing that could provide specific ceRNET profiles for neurodegenerative disorders, paving the way to a better understanding of these diseases.

Natural compounds as inhibitors of transthyretin amyloidosis and neuroprotective agents: analysis of structural data for future drug design

Natural compounds, such as plant and fruit extracts have shown neuroprotective effect against neurodegenerative diseases. It has been reported that several natural compounds binding to transthyretin (TTR) can be useful in amyloidosis prevention. TTR is a transporter protein that under physiological condition carries thyroxine (T4) and retinol in plasma and in cerebrospinal fluid (CSF); it also has a neuroprotective role against Alzheimer's disease (AD). However, TTR also is an amyloidogenic protein responsible for familial amyloid polyneuropathy (FAP) and familial amyloid cardiomyopathy (FAC). The TTR amyloidogenic potential is speeded up by several point mutations. One therapeutic strategy against TTR amyloidosis is the stabilisation of the native tetramer by natural compounds and small molecules. In this review, we examine the natural products that, starting from 2012 to present, have been studied as a stabiliser of TTR tetramer. In particular, we discussed the chemical and structural features which will be helpful for future drug design of new TTR stabilisers.

Neuroprotective and neuro-survival properties of safinamide against methamphetamine-induced neurodegeneration: Hypothetic possible role of BDNF/TrkB/PGC-1α signaling pathway and mitochondrial uncoupling protein -2(UCP-2)

Methamphetamine is a behavioral psychostimulant that has a high potential for misuse and induction of neurotoxicity. Safinamide is a novel inhibitor of monoamine oxidase B (MAOB) with neuroprotective properties. Methamphetamine abuse causes dysfunction in the respiratory chain of the mitochondria, but the specific signaling mechanism and role of the uncoupling protein-2(UCP-2) remain unclear. As we know, some indirect evidence indicates that neurodegeneration can be caused by inhibition of the brain-derived neurotrophic factor (BDNF) receptor, TrkB and its downstream signaling pathway, such as the PGC-1α protein. Neuroprotective strategies and approaches to the management, treatment or prevention of methamphetamine-induced neurodegeneration by modulating BDNF / TrkB / PGC-1α-UCP-2 can be considered as novel therapeutic approaches to these psychostimulant neurochemical and neurobehavioral approaches. Previous studies have shown that safinamide, a monoamine oxidase-B (MAOB) inhibitor, can function as a neuroprotective agent and inhibit the neurodegenerative process especially in Parkinson's disease but its impact on other neurodegenerative processes and drug-induced neurotoxicity remain unclear. Although there is some evidence that BDNF / TrkB / PGC-1α-UCP-2 signaling pathway and mitochondrial UCP-2 mediated safinamide induced neuroprotection but it's exact and precise mechanism of action and neuroprotective effects in neurodegenerative disorder and the protective properties against methamphetamine induced neurodegeneration and the role of BDNF / TrkB / PGC-1α signaling pathway and role of mitochondrial UCP-2 in this process have not yet been clarified. Therefore, in subjects addicted to methamphetamine, we hypothesized that safinamide will provide neuroprotection against methamphetamine-prompted neurodegeneration, and it appears that BDNF / TrkB / PGC-1α signaling pathway and mitochondrial UCP-2 are likely to play a critical role.

Circulating microRNAs Profile in Patients With Transthyretin Variant Amyloidosis

Transthyretin variant amyloidosis (ATTRv) is a rare autosomal dominant disease characterized by the accumulation of amyloid in many organs, mostly causing a sensory-motor neuropathy, cardiomyopathy, and dysautonomia. The aim of the study was to report microRNAs (miRNAs) expression profile identified in the blood of ATTRv patients. Ten ATTRv patients, 10 asymptomatic carriers of transthyretin variant (TTRv), 10 patients with Charcot-Marie-Tooth (CMT) disease, and 10 healthy controls were studied. Human Schwann cells cultures were used to study the regulatory effects of miR-150-5p on the expression of cAMP response element-binding protein (CREB), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF). ATTRv patients had 33 miRNAs up-regulated and 48 down-regulated versus healthy controls; 9 miRNAs were up-regulated and 30 down-regulated versus CMT patients; 19 miRNAs were up-regulated and 38 down-regulated versus asymptomatic TTRv carriers. Twelve out of the 19 upregulated miRNAs had a fold increase higher than 100. The validation experiment indicated miR-150-5p as a valuable biomarker to differentiate ATTRv patients from asymptomatic TTRv carriers (AUC: 0.9728; p < 0.0001). Schwann cells culture model demonstrated that miR-150-5p is a powerful negative regulator of CREB, BDNF, and NGF genes. Identification of deregulated miRNAs can help in understanding the complex pathomechamism underlying the development of ATTRv and related multisystemic pathology. Further investigations are needed on the role of circulating miR-150-5p to predict the shift of TTRv carriers from an asymptomatic status to symptoms appearance.

Characterising lipoteichoic acid as an in vitro model of acute neuroinflammation

Toll-like receptor 2 (TLR2) is a primary sensor for pathogens, including those derived from gram-positive bacteria. It can also mediate the effects of endogenous inflammatory signals such as β-amyloid peptide (Aβ), thus promoting the microglial activation and subsequent neuronal dysfunction, characteristic of chronic neuroinflammatory conditions. More recently, a role for TLR2 has been proposed in the pathogenesis of disorders associated with acute inflammation, including anxiety and depression. The current study aims to characterise the acute effects of the TLR2 agonist lipoteichoic acid (LTA) on microglial activation and neuronal integrity, and to evaluate the influence of LTA exposure on sensitivity to the inflammation and neuronal dysfunction associated with Aβ. Using BV2 and N2a cells as an in vitro model, we highlight that acute exposure to LTA robustly promotes inflammatory cytokine and nitric oxide (NO) production in microglia but also in neurons, similar to that reported under longer-term and chronic inflammatory conditions. Moreover, we find that exposure to LTA can enhance sensitivity to subthreshold Aβ, promoting an 'M1'-like phenotype in microglia and provoking dysregulation of neuronal activity in acute hippocampal slices. Anti-inflammatory agents, including mimetics of brain-derived neurotrophic factor (BDNF), have proven effective at alleviating chronic neuroinflammatory complications. We further examined the effects of 7,8,3-trihydroxyflavone (7,8,3-THF), a small-molecule TrkB agonist, on LTA-induced microglial activation. We report that 7,8,3-THF can significantly ameliorate interleukin (IL)-6 and NO production in LTA-stimulated BV2 cells. Taken together, our findings offer support for exploration of TLR2 as a potential target for therapeutic intervention into acute neuroinflammatory conditions. Moreover we propose that exposure to gram-positive bacterial pathogens may promote sensitivity to the inflammatory changes characteristic of the aged brain.

Circular RNA circDLGAP4 exerts neuroprotective effects via modulating miR-134-5p/CREB pathway in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease which is characterized by the substantia nigra dopaminergic neurons denatured. Circular RNA (circRNA) DLGAP4 (circDLGAP4) was found to have neuroprotective effect. In this study, we aimed to investigate whether circDLGAP4 participates in the progression of PD. Here, our results showed that circDLGAP4 expression was decreased in MPTP-induced PD mouse model and MPP⁺-induced PD cell models. In vitro study revealed that circDLGAP4 could promote viability, reduce apoptosis, decrease mitochondrial damage, enhance autophagy and thereby attenuated the neurotoxic effects of MPP⁺ in SH-SY5Y and MN9D cells. Further research suggested that circDLGAP4 exerted its functions via regulating miR-134-5p. Moreover, we demonstrated that CREB was a target of miR-134-5p and CREB expression could be regulated by circDLGAP4/miR-134-5p axis. CircDLGAP4/miR-134-5p could also modulate the activation of CREB signaling and thereby influence the expression of CREB target genes including BDNF, Bcl-2 and PGC-1α in SH-SY5Y and MN9D cells. In all, our study identifies that circDLGAP4 exerts neuroprotective effects via modulating miR-134-5p/CREB pathway both in human and mouse.