More Insight into BDNF against Neurodegeneration: Anti-Apoptosis, Anti-Oxidation, and Suppression of Autophagy

mTOR Signaling in BDNF-Treated Guinea Pigs after Ototoxic Deafening

The mammalian target of rapamycin (mTOR) signaling plays a critical role in cell homeostasis, growth and survival. Here, we investigated the localization of the main mTOR signaling proteins in the organ of Corti of normal-hearing and deafened guinea pigs, as well as their possible modulation by exogenously administered brain-derived neurotrophic factor (BDNF) in deafened guinea pigs. Animals were ototoxically deafened by systemic administration of kanamycin and furosemide, and one week later, the right cochleas were treated with gelatin sponge soaked in rhBDNF, while the left cochleas were used as negative controls. Twenty-four hours after treatment, animals were euthanized, and the cochleas were processed for subsequent analysis. Through immunofluorescence, we demonstrated the localization of AKT, pAKT, mTOR, pmTOR and PTEN proteins throughout the cochlea of guinea pigs for the first time, with a higher expression in supporting cells. Moreover, an increase in mTOR immunostaining was observed in BDNF-treated cochleas by means of fluorescence intensity compared to the other groups. Conversely, Western blot analysis showed no significant differences in the protein levels between groups, probably due to dilution of proteins in the neighboring tissues of the organ of Corti. Altogether, our data indicate that mTOR signaling proteins are expressed by the organ of Corti (with a major role for supporting cells) and that the modulation of mTOR may be a protective mechanism triggered by BDNF in the degenerating organ of Corti.

The Effect of Remifentanil, MgSO4, or Remifentanil-MgSO4 as Neuroprotectors on BDNF, MAC, and Caspase-3 Levels in Wistar Rats with Traumatic Brain Injury

BACKGROUND: Traumatic brain injury (TBI) can lead to cell death and neurologic dysfunction. Meanwhile, Remifentanyl is an opioid with potent analgesia, while magnesium sulfate (MgSO4) has antinociceptive properties that can prevent hemodynamic instability during laryngoscopy. AIM: This study aims to examine the effect of remifentanil, MgSO4 and their combination on BDNF, MAC, and Caspase-3 levels in Wistar rat models with TBI. METHODOLOGY: An experimental study was conducted on 30 male Wistar rats which were randomly divided into five groups. The control group (G1) received normal saline, the induced group (G2) received normal saline after TBI induction using the modified Feeney method, and the treated group (G3, G4, and G5) received remifentanil, MgSO4, and their combination after TBI induction. The rats’ brain tissues were analyzed for BDNF, MAC, and Caspase-3 levels using ELISA. The data were analyzed statistically with ANOVA followed by post hoc Multiple Comparison Test (p < 0.05). RESULTS: Treatment with remifentanil, MgSO4 or the combination of both in TBI subjects reduced MAC and Caspase-3 but increased the BDNF level. The post hoc multiple comparisons showed significant differences in all groups except groups 3 and 5 in terms of MAC (p = 0.190) and Caspase-3 (p = 0.999). The combination of remifentanil-MgSO4 increased BDNF levels significantly. CONCLUSION: The administration of remifentanil, MgSO4 , or their combination can serve as a neuroprotector in Wistar rat models with TBI by lowering MAC and Caspase-3 as well as increasing BDNF levels.

Schisandra chinensis Lignans Exert Antidepressant Effects by Promoting BV2 Microglia Polarization toward the M2 Phenotype through the Activation of the Cannabinoid Receptor Type-2-Signal Transducer and Activator of Transcription 6 Pathway

Based on the current results, they showed that Schisandra chinensis lignans (SCL) ameliorated depressive-like behaviors in chronic unpredictable mild stress (CUMS) mice, alleviated neuroinflammation, and improved neuronal injury. This study aimed to explore whether SCL exerted antidepressant effects through inhibiting neuroinflammation, in turn improving neuronal injury. In vitro studies revealed that SCL blocked lipopolysaccharide-increased BV2 microglial M1 but promoted the M2 phenotype. The BV2-N2a interaction model suggested that increasing the M2 phenotype of BV2 played neuroprotective effects. The current studies demonstrated that SCL up-regulated the expression of CUMS- and LPS-decreased cannabinoid receptor type-2 (CB2R) mRNA. In vitro studies showed that the transfection of BV2 with siCrn2 blocked the SCL-increased M2 phenotype via the inactivating signal transducer and activator of transcription 6 (STAT6) pathway, further decreasing the viability of N2a cells. Finally, the possible pharmacodynamic compounds, γ-schisandrin and schisantherin A, were indicated by AutoDuck analysis. Overall, our study showed that SCL promoted microglia polarization toward the M2 phenotype, in turn exerting neuroprotective effects by activating CB2R-STAT6 signaling further to play antidepressant roles.

Moderate Aerobic Exercise Regulates Follicular Dysfunction by Initiating Brain-Derived Neurotrophic Factor (BDNF)-Mediated Anti-Apoptotic Signaling Pathways in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder among women. Moderate aerobic exercise intervention is considered an initial treatment strategy for managing PCOS. Brain-derived neurotrophic factor (BDNF) is an important molecular mediator and a beneficial response to exercise. We aimed to investigate the expression pattern and underlying molecular mechanisms of this neurotrophic factor during follicle development in ovarian tissues. The PCOS model was established by subcutaneous injection of 60 mg/kg dehydroepiandrosterone (DHEA) into the neck of Sprague Dawley rats for 35 consecutive days. PCOS rats then received aerobic exercise for 8 weeks. Body/ovarian weight and peripheral serum hormone levels were observed. Immunohistochemistry combined with Western blot analysis and fluorescence quantitative polymerase chain reaction were used to detect the changes in BDNF-TrkB/p75NTR pathway, apoptosis, and inflammatory factors. We show that moderate aerobic exercise not only reverses the PCOS phenotype but also activates the BDNF-TrkB pathway and initiates downstream targets. p-TrkB upregulates and phosphorylates phosphatidylinositol 3-kinase (PI3K) and protein kinase B (Akt) to inhibit apoptosis. In addition, aerobic exercise therapy reduces the high expression of p75NTR in the ovarian tissue of PCOS rats and initiates the anti-apoptotic effect from the downstream pathway of NF-κB/JNK. Our in vitro results state that treatment with BDNF ameliorated dihydrotestosterone (DHT)-induced granulosa cells (GCs) apoptosis by provoking p-TrkB activation and upregulating the PI3K/AKT pathway. The present study suggests that moderate aerobic exercise regulates follicular dysfunction in PCOS-like rats. One possible mechanism is to initiate the BDNF-mediated anti-apoptotic signaling pathway.

Non-Pharmacological Therapeutic Options for the Treatment of Alzheimer's Disease

Alzheimer's disease is a growing global crisis in need of urgent diagnostic and therapeutic strategies. The current treatment strategy mostly involves immunotherapeutic medications that have had little success in halting disease progress. Hypotheses for pathogenesis and development of AD have been expanded to implicate both organ systems as well as cellular reactions. Non-pharmacologic interventions ranging from minimally to deeply invasive have attempted to address these diverse contributors to AD. In this review, we aim to delineate mechanisms underlying such interventions while attempting to provide explanatory links between the observed differences in disease states and postulated metabolic or structural mechanisms of change. The techniques discussed are not an exhaustive list of non-pharmacological interventions against AD but provide a foundation to facilitate a deeper understanding of the area of study.

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.

A Brief Overview on BDNF-Trk Pathway in the Nervous System: A Potential Biomarker or Possible Target in Treatment of Multiple Sclerosis?

The growing incidence of neurodegenerative disorders in our populations is leading the research to identify potential biomarkers and targets for facilitating their early management and treatments. Biomarkers represent the crucial indicators of both physiological and pathological processes. Specific changes in molecular and cellular mechanisms of physiological processes result in biochemical alterations at systemic level, which can give us comprehensive information regarding the nature of any disease. In addition, any disease biomarker should be specific and reliable, able to consent of distinguishing the physiological condition of a tissue, organ, or system from disease, and be diverse among the various diseases, or subgroups or phenotypes of them. Accordingly, biomarkers can predict chances for diseases, facilitate their early diagnosis, and set guidelines for the development of new therapies for treating diseases and disease-making process. Here, we focus our attention on brain neurotrophic factor (BDNF)–tropomyosin receptor kinase (Trk) pathway, describing its multiple roles in the maintenance of central nervous system (CNS) health, as well as its implication in the pathogenesis of multiple sclerosis (MS). In addition, we also evidence the features of such pathway, which make of it a potential MS biomarker and therapeutic target.

Inhibiting BDNF Signaling Upregulates Hippocampal H3K9me3 in a Manner Dependent On In Vitro Aging and Oxidative Stress

Histone modifications are key contributors to the cognitive decline that occurs in aging and Alzheimer's disease. Our lab has previously shown that elevated H3K9me3 in aged mice is correlated with synaptic loss, cognitive impairment and a reduction in brain derived neurotrophic factor (BDNF). However, the mechanism of H3K9me3 regulation remains poorly understood. In this study, we investigated the role of age-associated stressors on H3K9me3 regulation and examined if changes in H3K9me3 were age dependent. We used cultured hippocampal neurons at 6, 12, and 21 days in vitro (DIV) to examine the effect of different stressors on H3K9me3 across neuron ages. We found that the oxidative stressor hydrogen peroxide (H2O2) does not induce H3K9me3 in 12 DIV neurons. Inhibiting BDNF signaling via TrkB-Fc elevated H3K9me3 in 12 and 21 DIV neurons compared to 6 DIV neurons. Antioxidant treatment prevented H3K9me3 elevation in 12 DIV neurons treated with TrkB-Fc and H2O2. H2O2 elevated the epigenetic regulator SIRT1 in 6 DIV neurons but did not increase H3K9me3 levels. Our findings demonstrate that inhibiting BDNF signaling elevates hippocampal H3K9me3 in a manner dependent on in vitro age and oxidative stress.

Aggregation chimeras provide evidence of in vivo intercellular correction in ovine CLN6 neuronal ceroid lipofuscinosis (Batten disease)

The neuronal ceroid lipofuscinoses (NCLs; Batten disease) are fatal, mainly childhood, inherited neurodegenerative lysosomal storage diseases. Sheep affected with a CLN6 form display progressive regionally defined glial activation and subsequent neurodegeneration, indicating that neuroinflammation may be causative of pathogenesis. In this study, aggregation chimeras were generated from homozygous unaffected normal and CLN6 affected sheep embryos, resulting in seven chimeric animals with varied proportions of normal to affected cells. These sheep were classified as affected-like, recovering-like or normal-like, based on their cell-genotype ratios and their clinical and neuropathological profiles. Neuropathological examination of the affected-like animals revealed intense glial activation, prominent storage body accumulation and severe neurodegeneration within all cortical brain regions, along with vision loss and decreasing intracranial volumes and cortical thicknesses consistent with ovine CLN6 disease. In contrast, intercellular communication affecting pathology was evident at both the gross and histological level in the normal-like and recovering-like chimeras, resulting in a lack of glial activation and rare storage body accumulation in only a few cells. Initial intracranial volumes of the recovering-like chimeras were below normal but progressively recovered to about normal by two years of age. All had normal cortical thicknesses, and none went blind. Extended neurogenesis was evident in the brains of all the chimeras. This study indicates that although CLN6 is a membrane bound protein, the consequent defect is not cell intrinsic. The lack of glial activation and inflammatory responses in the normal-like and recovering-like chimeras indicate that newly generated cells are borne into a microenvironment conducive to maturation and survival.

Neurotrophins as Therapeutic Agents for Parkinson’s Disease; New Chances From Focused Ultrasound?

Magnetic Resonance–guided Focused Ultrasound (MRgFUS) represents an effective micro-lesioning approach to target pharmaco-resistant tremor, mostly in patients afflicted by essential tremor (ET) and/or Parkinson’s disease (PD). So far, experimental protocols are verifying the clinical extension to other facets of the movement disorder galaxy (i.e., internal pallidus for disabling dyskinesias). Aside from those neurosurgical options, one of the most intriguing opportunities of this technique relies on its capability to remedy the impermeability of blood–brain barrier (BBB). Temporary BBB opening through low-intensity focused ultrasound turned out to be safe and feasible in patients with PD, Alzheimer’s disease, and amyotrophic lateral sclerosis. As a mere consequence of the procedures, some groups described even reversible but significant mild cognitive amelioration, up to hippocampal neurogenesis partially associated to the increased of endogenous brain-derived neurotrophic factor (BDNF). A further development elevates MRgFUS to the status of therapeutic tool for drug delivery of putative neurorestorative therapies. Since 2012, FUS-assisted intravenous administration of BDNF or neurturin allowed hippocampal or striatal delivery. Experimental studies emphasized synergistic modalities. In a rodent model for Huntington’s disease, engineered liposomes can carry glial cell line–derived neurotrophic factor (GDNF) plasmid DNA (GDNFp) to form a GDNFp-liposome (GDNFp-LPs) complex through pulsed FUS exposures with microbubbles; in a subacute MPTP-PD model, the combination of intravenous administration of neurotrophic factors (either through protein or gene delivery) plus FUS did curb nigrostriatal degeneration. Here, we explore these arguments, focusing on the current, translational application of neurotrophins in neurodegenerative diseases.

The Complex Mechanisms by Which Neurons Die Following DNA Damage in Neurodegenerative Diseases

Human cells are exposed to numerous exogenous and endogenous insults every day. Unlike other molecules, DNA cannot be replaced by resynthesis, hence damage to DNA can have major consequences for the cell. The DNA damage response contains overlapping signalling networks that repair DNA and hence maintain genomic integrity, and aberrant DNA damage responses are increasingly described in neurodegenerative diseases. Furthermore, DNA repair declines during aging, which is the biggest risk factor for these conditions. If unrepaired, the accumulation of DNA damage results in death to eliminate cells with defective genomes. This is particularly important for postmitotic neurons because they have a limited capacity to proliferate, thus they must be maintained for life. Neuronal death is thus an important process in neurodegenerative disorders. In addition, the inability of neurons to divide renders them susceptible to senescence or re-entry to the cell cycle. The field of cell death has expanded significantly in recent years, and many new mechanisms have been described in various cell types, including neurons. Several of these mechanisms are linked to DNA damage. In this review, we provide an overview of the cell death pathways induced by DNA damage that are relevant to neurons and discuss the possible involvement of these mechanisms in neurodegenerative conditions.

The effect of propofol on hypoxia- and TNF-α-mediated BDNF/TrkB pathway dysregulation in primary rat hippocampal neurons

AIMS

Hypoxia and inflammation may lead to BDNF/TrkB dysregulation and neurological disorders. Propofol is an anesthetic with neuroprotective properties. We wondered whether and how propofol affected BDNF/TrkB pathway in hippocampal neurons and astrocytes.

METHODS

Primary rat hippocampal neurons and astrocytes were cultured and exposed to propofol followed by hypoxia or TNF-α treatment. The expression of BDNF and the expression/truncation/phosphorylation of TrkB were measured. The underlying mechanisms were investigated.

RESULTS

Hypoxia and TNF-α reduced the expression of BDNF, which was reversed by pretreatment of 25 μM propofol in hippocampal neurons. Furthermore, hypoxia and TNF-α increased the phosphorylation of ERK and phosphorylation of CREB at Ser142, while reduced the phosphorylation of CREB at Ser133, which were all reversed by 25 μM propofol and 10 μM ERK inhibitor. In addition, hypoxia or TNF-α did not affect TrkB expression, truncation, or phosphorylation in hippocampal neurons and astrocytes. However, in hippocampal neurons, 50 μM propofol induced TrkB phosphorylation, which may be mediated by p35 expression and Cdk5 activation, as suggested by the data showing that blockade of p35 or Cdk5 expression mitigated propofol-induced TrkB phosphorylation.

CONCLUSIONS

Propofol modulated BDNF/TrkB pathway in hippocampal neurons via ERK/CREB and p35/Cdk5 under the condition of hypoxia or TNF-α exposure.

Influence of N-Arachidonoyl Dopamine and N-Docosahexaenoyl Dopamine on the Expression of Neurotrophic Factors in Neuronal Differentiated Cultures of Human Induced Pluripotent Stem Cells under Conditions of Oxidative Stress

Oxidative stress (OS) is implicated in the pathogenesis of several neurodegenerative diseases. We have previously shown that N-acyl dopamines (N-ADA and N-DDA) protect the neural cells of healthy donors and patients with Parkinson’s disease from OS. In this study, we assessed the effects of N-acyl dopamines on the expression of neurotrophic factors in human-induced pluripotent stem cell-derived neuronal cultures enriched with dopaminergic neurons under conditions of OS induced by hydrogen peroxide. We showed that hydrogen peroxide treatment increased BDNF but not GDNF mRNA levels, while it did not affect the secretion of corresponding proteins into the culture medium of these cells. Application of N-acyl dopamines promoted BDNF release into the culture medium. Under conditions of OS, N-DDA also increased TRKB, TRKC and RET mRNA levels. Furthermore, N-acyl dopamines prevented cell death 24 h after OS induction and promoted the expression of antioxidant enzymes GPX1, GPX7, SOD1, SOD2 and CAT, as well as reduced the BAX/BCL2 mRNA ratio. These findings indicate that stimulation of the expression of neurotrophic factors and their receptors may underlie the neuroprotective effects of N-acyl dopamines in human neurons.

HINT1 deficiency in aged mice reduces anxiety-like and depression-like behaviours and enhances cognitive performances

Histidine triad nucleotide-binding protein 1 (HINT1) is regarded as a haplo-insufficient tumour suppressor and is closely associated with many neuropsychiatric disorders, including major depressive disorders. In addition, HINT1 knockout (KO) mice exhibit anxiolytic-like behaviour, antidepression-like behaviour, and enhanced cognitive performance in several studies. However, it is still unclear whether aging contributes to these changes in the emotion and cognition of HINT1 KO mice. This study examined the role of aging in anxiety-like and depression-like behaviours and cognition behaviours in aged HINT1 KO mice compared with young HINT1 KO mice and their wild-type littermates, along with a number of molecular biological methods. In a battery of behavioural tests, aged wild-type mice showed increased anxiety-like and depression-like behaviours and decreased cognitive performance, along with lower expression levels of glutathione peroxidase, enhanced amount of malondialdehyde, and decreased expression levels of brain-derived neurotrophic factor and tyrosine kinase B in the hippocampus and PFC compared to young wild-type mice. HINT1 KO mice showed reduced anxiety-like and depression-like behaviours and enhanced cognitive performance compared to age-matched wild-type mice. In addition, HINT1 KO mice also showed increased GSH-Px and superoxide dismutase, and decreased malondialdehyde, together with enhanced BDNF and Trk-B expression in the hippocampus and PFC. However, when compared with young HINT1 KO mice, aged HINT1 KO mice did not show increased anxiety-like and depression-like behaviours. And there are no differences in the expression level of superoxide dismutase, malondialdehyde, BDNF, and Trk-B between aged and young HINT1 KO mice. In summary, HINT1 deficiency can counteract age-related emotion and cognition dysfunction.

Pleiotropic effects of BDNF on the cerebellum and hippocampus: Implications for neurodevelopmental disorders

Brain-derived neurotrophic factor (BDNF) is one of the most studied neurotrophins in the mammalian brain, essential not only to the development of the central nervous system but also to synaptic plasticity. BDNF is present in various brain areas, but highest levels of expression are seen in the cerebellum and hippocampus. After birth, BDNF acts in the cerebellum as a mitogenic and chemotactic factor, stimulating the cerebellar granule cell precursors to proliferate, migrate and maturate, while in the hippocampus BDNF plays a fundamental role in synaptic transmission and plasticity, representing a key regulator for the long-term potentiation, learning and memory. Furthermore, the expression of BDNF is highly regulated and changes of its expression are associated with both physiological and pathological conditions. The purpose of this review is to provide an overview of the current state of knowledge on the BDNF biology and its neurotrophic role in the proper development and functioning of neurons and synapses in two important brain areas of postnatal neurogenesis, the cerebellum and hippocampus. Dysregulation of BDNF expression and signaling, resulting in alterations in neuronal maturation and plasticity in both systems, is a common hallmark of several neurodevelopmental diseases, such as autism spectrum disorder, suggesting that neuronal malfunction present in these disorders is the result of excessive or reduced of BDNF support. We believe that the more the relevance of the pathophysiological actions of BDNF, and its downstream signals, in early postnatal development will be highlighted, the more likely it is that new neuroprotective therapeutic strategies will be identified in the treatment of various neurodevelopmental disorders.

Long-Term Effects of Ionizing Radiation on the Hippocampus: Linking Effects of the Sonic Hedgehog Pathway Activation with Radiation Response

Radiation therapy represents one of the primary treatment modalities for primary and metastatic brain tumors. Although recent advances in radiation techniques, that allow the delivery of higher radiation doses to the target volume, reduce the toxicity to normal tissues, long-term neurocognitive decline is still a detrimental factor significantly affecting quality of life, particularly in pediatric patients. This imposes the need for the development of prevention strategies. Based on recent evidence, showing that manipulation of the Shh pathway carries therapeutic potential for brain repair and functional recovery after injury, here we evaluate how radiation-induced hippocampal alterations are modulated by the constitutive activation of the Shh signaling pathway in Patched 1 heterozygous mice (Ptch1^+/-). Our results show, for the first time, an overall protective effect of constitutive Shh pathway activation on hippocampal radiation injury. This activation, through modulation of the proneural gene network, leads to a long-term reduction of hippocampal deficits in the stem cell and new neuron compartments and to the mitigation of radio-induced astrogliosis, despite some behavioral alterations still being detected in Ptch1^+/- mice. A better understanding of the pathogenic mechanisms responsible for the neural decline following irradiation is essential for identifying prevention measures to contain the harmful consequences of irradiation. Our data have important translational implications as they suggest a role for Shh pathway manipulation to provide the therapeutic possibility of improving brain repair and functional recovery after radio-induced injury.

Transplantation of rat cranial bone-derived mesenchymal stem cells promotes functional recovery in rats with spinal cord injury

Cell-based therapy using mesenchymal stem cells (MSCs) is a novel treatment strategy for spinal cord injury (SCI). MSCs can be isolated from various tissues, and their characteristics vary based on the source. However, reports demonstrating the effect of transplanted rat cranial bone-derived MSCs (rcMSCs) on rat SCI models are lacking. In this study, we determined the effect of transplanting rcMSCs in rat SCI models. MSCs were established from collected bone marrow and cranial bones. SCI rats were established using the weight-drop method and transplanted intravenously with MSCs at 24 h post SCI. The recovery of motor function and hindlimb electrophysiology was evaluated 4 weeks post transplantation. Electrophysiological recovery was evaluated by recording the transcranial electrical stimulation motor-evoked potentials. Tissue repair after SCI was assessed by calculating the cavity ratio. The expression of genes involved in the inflammatory response and cell death in the spinal cord tissue was assessed by real-time polymerase chain reaction. The transplantation of rcMSCs improved motor function and electrophysiology recovery, and reduced cavity ratio. The expression of proinflammatory cytokines was suppressed in the spinal cord tissues of the rats that received rcMSCs. These results demonstrate the efficacy of rcMSCs as cell-based therapy for SCI.

Epilepsy in Neurodegenerative Diseases: Related Drugs and Molecular Pathways

Epilepsy is a chronic disease of the central nervous system characterized by an electrical imbalance in neurons. It is the second most prevalent neurological disease, with 50 million people affected around the world, and 30% of all epilepsies do not respond to available treatments. Currently, the main hypothesis about the molecular processes that trigger epileptic seizures and promote the neurotoxic effects that lead to cell death focuses on the exacerbation of the glutamate pathway and the massive influx of Ca2+ into neurons by different factors. However, other mechanisms have been proposed, and most of them have also been described in other neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, or multiple sclerosis. Interestingly, and mainly because of these common molecular links and the lack of effective treatments for these diseases, some antiseizure drugs have been investigated to evaluate their therapeutic potential in these pathologies. Therefore, in this review, we thoroughly investigate the common molecular pathways between epilepsy and the major neurodegenerative diseases, examine the incidence of epilepsy in these populations, and explore the use of current and innovative antiseizure drugs in the treatment of refractory epilepsy and other neurodegenerative diseases.

Hepatic Encephalopathy: From Metabolic to Neurodegenerative

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome of both acute and chronic liver disease. As a metabolic disorder, HE is considered to be reversible and therefore is expected to resolve following the replacement of the diseased liver with a healthy liver. However, persisting neurological complications are observed in up to 47% of transplanted patients. Several retrospective studies have shown that patients with a history of HE, particularly overt-HE, had persistent neurological complications even after liver transplantation (LT). These enduring neurological conditions significantly affect patient's quality of life and continue to add to the economic burden of chronic liver disease on health care systems. This review discusses the journey of the brain through the progression of liver disease, entering the invasive surgical procedure of LT and the conditions associated with the post-transplant period. In particular, it will discuss the vulnerability of the HE brain to peri-operative factors and post-LT conditions which may explain non-resolved neurological impairment following LT. In addition, the review will provide evidence; (i) supporting overt-HE impacts on neurological complications post-LT; (ii) that overt-HE leads to permanent neuronal injury and (iii) the pathophysiological role of ammonia toxicity on astrocyte and neuronal injury/damage. Together, these findings will provide new insights on the underlying mechanisms leading to neurological complications post-LT.

Potential Roles of Sestrin2 in Alzheimer's Disease: Antioxidation, Autophagy Promotion, and Beyond

Alzheimer’s disease (AD) is the most common age-related neurodegenerative disease. It presents with progressive memory loss, worsens cognitive functions to the point of disability, and causes heavy socioeconomic burdens to patients, their families, and society as a whole. The underlying pathogenic mechanisms of AD are complex and may involve excitotoxicity, excessive generation of reactive oxygen species (ROS), aberrant cell cycle reentry, impaired mitochondrial function, and DNA damage. Up to now, there is no effective treatment available for AD, and it is therefore urgent to develop an effective therapeutic regimen for this devastating disease. Sestrin2, belonging to the sestrin family, can counteract oxidative stress, reduce activity of the mammalian/mechanistic target of rapamycin (mTOR), and improve cell survival. It may therefore play a crucial role in neurodegenerative diseases like AD. However, only limited studies of sestrin2 and AD have been conducted up to now. In this article, we discuss current experimental evidence to demonstrate the potential roles of sestrin2 in treating neurodegenerative diseases, focusing specifically on AD. Strategies for augmenting sestrin2 expression may strengthen neurons, adapting them to stressful conditions through counteracting oxidative stress, and may also adjust the autophagy process, these two effects together conferring neuronal resistance in cases of AD.

7,8-dihydroxyflavone ameliorates motor deficits via regulating autophagy in MPTP-induced mouse model of Parkinson's disease

Parkinson’s disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra and diminished dopamine content in the striatum. Recent reports show that 7,8-dihydroxyflavone (DHF), a TrkB agonist, attenuates the α-synuclein deposition and ameliorates motor deficits. However, the underlying mechanism is unclear. In this study, we investigated whether autophagy is involved in the clearance of α-synuclein and the signaling pathway through which DHF exerts therapeutic effects. We found that the administration of DHF (5 mg/kg/day, i.p.) prevented the loss of dopaminergic neurons and improved motor functions in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD, whereas these protective effects of DHF were completely blocked by autophagy inhibitor chloroquine (CQ). Further in vitro studies showed that autophagy was inhibited in N2A cells treated with 1-methyl-4-phenylpyridinium (MPP⁺), as reflected by a significant decrease in the expressions of autophagy marker proteins (Beclin1 and LC3II) and an increase in the expression of autophagic flux marker p62. DHF restored the impaired autophagy to control level in MPP⁺-treated N2A cells by inhibiting the ERK-LKB1-AMPK signaling pathway. Taken together, these results demonstrate that DHF exerts therapeutic effects in MPTP/MPP⁺-induced neurotoxicity by inhibiting the ERK-LKB1-AMPK signaling pathway and subsequently improving impaired autophagy.

Mitochondria in Neuronal Health: From Energy Metabolism to Parkinson's Disease

Mitochondria are the main suppliers of neuronal adenosine triphosphate and play a critical role in brain energy metabolism. Mitochondria also serve as Ca²⁺ sinks and anabolic factories and are therefore essential for neuronal function and survival. Dysregulation of neuronal bioenergetics is increasingly implicated in neurodegenerative disorders, particularly Parkinson's disease. This review describes the role of mitochondria in energy metabolism under resting conditions and during synaptic transmission, and presents evidence for the contribution of neuronal mitochondrial dysfunction to Parkinson's disease.

Oxidative-Signaling in Neural Stem Cell-Mediated Plasticity: Implications for Neurodegenerative Diseases

The adult mammalian brain is capable of generating new neurons from existing neural stem cells (NSCs) in a process called adult neurogenesis. This process, which is critical for sustaining cognition and mental health in the mature brain, can be severely hampered with ageing and different neurological disorders. Recently, it is believed that the beneficial effects of NSCs in the injured brain relies not only on their potential to differentiate and integrate into the preexisting network, but also on their secreted molecules. In fact, further insight into adult NSC function is being gained, pointing to these cells as powerful endogenous "factories" that produce and secrete a large range of bioactive molecules with therapeutic properties. Beyond anti-inflammatory, neurogenic and neurotrophic effects, NSC-derived secretome has antioxidant proprieties that prevent mitochondrial dysfunction and rescue recipient cells from oxidative damage. This is particularly important in neurodegenerative contexts, where oxidative stress and mitochondrial dysfunction play a significant role. In this review, we discuss the current knowledge and the therapeutic opportunities of NSC secretome for neurodegenerative diseases with a particular focus on mitochondria and its oxidative state.

Betulinic Acid Hydroxamate is Neuroprotective and Induces Protein Phosphatase 2A-Dependent HIF-1α Stabilization and Post-transcriptional Dephosphorylation of Prolyl Hydrolase 2

Huntington's disease (HD) is a neurodegenerative disorder characterized by unwanted choreatic movements, behavioral and psychiatric disturbances, and dementia. The activation of the hypoxic response pathway through the pharmacological inhibition of hypoxia-inducing factor (HIF) prolyl-hydroxylases (PHDs) is a promising approach for neurodegenerative diseases, including HD. Herein, we have studied the mechanism of action of the compound Betulinic acid hydroxamate (BAH), a hypoximimetic derivative of betulinic acid, and its efficacy against striatal neurodegeneration using complementary approaches. Firstly, we showed the molecular mechanisms through which BAH modifies the activity of the PHD2 prolyl hydroxylase, thus directly affecting HIF-1α stability. BAH treatment reduces PHD2 phosphorylation on Ser-125 residue, responsible for the control of its hydrolase activity. HIF activation by BAH is inhibited by okadaic acid and LB-100 indicating that a protein phosphatase 2A (PP2A) is implicated in the mechanism of action of BAH. Furthermore, in striatal cells bearing a mutated form of the huntingtin protein, BAH stabilized HIF-1α protein, induced Vegf and Bnip3 gene expression and protected against mitochondrial toxin-induced cytotoxicity. Pharmacokinetic analyses showed that BAH has a good brain penetrability and experiments performed in a mouse model of striatal neurodegeneration induced by 3-nitropropionic acid showed that BAH improved the clinical symptoms. In addition, BAH also prevented neuronal loss, decreased reactive astrogliosis and microglial activation, inhibited the upregulation of proinflammatory markers, and improved antioxidant defenses in the brain. Taken together, our results show BAH's ability to activate the PP2A/PHD2/HIF pathway, which may have important implications in the treatment of HD and perhaps other neurodegenerative diseases.

Role of Plant-Derived Natural Compounds in Experimental Autoimmune Encephalomyelitis: A Review of the Treatment Potential and Development Strategy

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system that is mainly mediated by pathological T-cells. Experimental autoimmune encephalomyelitis (EAE) is a well-known animal model of MS that is used to study the underlying mechanism and offers a theoretical basis for developing a novel therapy for MS. Good therapeutic effects have been observed after the administration of natural compounds and their derivatives as treatments for EAE. However, there has been a severe lag in the research and development of drug mechanisms related to MS. This review examines natural products that have the potential to effectively treat MS. The relevant data were consulted in order to elucidate the regulated mechanisms acting upon EAE by the flavonoids, glycosides, and triterpenoids derived from natural products. In addition, novel technologies such as network pharmacology, molecular docking, and high-throughput screening have been gradually applied in natural product development. The information provided herein can help improve targeting and timeliness for determining the specific mechanisms involved in natural medicine treatment and lay a foundation for further study.

Neuroprotective Effects of Guanosine in Ischemic Stroke-Small Steps towards Effective Therapy

Guanosine (Guo) is a nucleotide metabolite that acts as a potent neuromodulator with neurotrophic and regenerative properties in neurological disorders. Under brain ischemia or trauma, Guo is released to the extracellular milieu and its concentration substantially raises. In vitro studies on brain tissue slices or cell lines subjected to ischemic conditions demonstrated that Guo counteracts destructive events that occur during ischemic conditions, e.g., glutaminergic excitotoxicity, reactive oxygen and nitrogen species production. Moreover, Guo mitigates neuroinflammation and regulates post-translational processing. Guo asserts its neuroprotective effects via interplay with adenosine receptors, potassium channels, and excitatory amino acid transporters. Subsequently, guanosine activates several prosurvival molecular pathways including PI3K/Akt (PI3K) and MEK/ERK. Due to systemic degradation, the half-life of exogenous Guo is relatively low, thus creating difficulty regarding adequate exogenous Guo distribution. Nevertheless, in vivo studies performed on ischemic stroke rodent models provide promising results presenting a sustained decrease in infarct volume, improved neurological outcome, decrease in proinflammatory events, and stimulation of neuroregeneration through the release of neurotrophic factors. In this comprehensive review, we discuss molecular signaling related to Guo protection against brain ischemia. We present recent advances, limitations, and prospects in exogenous guanosine therapy in the context of ischemic stroke.

Induction of oxidative stress and apoptosis in the injured brain: potential relevance to brain regeneration in zebrafish

Recent findings suggest a significant role of the brain-derived neurotrophic factor (BDNF) as a mediator of brain regeneration following a stab injury in zebrafish. Since BDNF has been implicated in many physiological processes, we hypothesized that these processes are affected by brain injury in zebrafish. Hence, we examined the impact of stab injury on oxidative stress and apoptosis in the adult zebrafish brain. Stab wound injury (SWI) was induced in the right telencephalic hemisphere of the adult zebrafish brain and examined at different time points. The biochemical variables of oxidative stress insult and transcript levels of antioxidant genes were assessed to reflect upon the oxidative stress levels in the brain. Immunohistochemistry was performed to detect the levels of early apoptotic marker protein cleaved caspase-3, and the transcript levels of pro-apoptotic and anti-apoptotic genes were examined to determine the effect of SWI on apoptosis. The activity of antioxidant enzymes, the level of lipid peroxidation (LPO) and reduced glutathione (GSH) were significantly increased in the injured fish brain. SWI also enhanced the expression of cleaved caspase-3 protein and apoptosis-related gene transcripts. Our results indicate induction of oxidative stress and apoptosis in the telencephalon of adult zebrafish brain by SWI. These findings contribute to the overall understanding of the pathophysiology of traumatic brain injury and adult neurogenesis in the zebrafish model and raise new questions about the compensatory physiological mechanisms in response to traumatic brain injury in the adult zebrafish brain.

Optogenetically Controlled Activity Pattern Determines Survival Rate of Developing Neocortical Neurons

A substantial proportion of neurons undergoes programmed cell death (apoptosis) during early development. This process is attenuated by increased levels of neuronal activity and enhanced by suppression of activity. To uncover whether the mere level of activity or also the temporal structure of electrical activity affects neuronal death rates, we optogenetically controlled spontaneous activity of synaptically-isolated neurons in developing cortical cultures. Our results demonstrate that action potential firing of primary cortical neurons promotes neuronal survival throughout development. Chronic patterned optogenetic stimulation allowed to effectively modulate the firing pattern of single neurons in the absence of synaptic inputs while maintaining stable overall activity levels. Replacing the burst firing pattern with a non-physiological, single pulse pattern significantly increased cell death rates as compared to physiological burst stimulation. Furthermore, physiological burst stimulation led to an elevated peak in intracellular calcium and an increase in the expression level of classical activity-dependent targets but also decreased Bax/BCL-2 expression ratio and reduced caspase 3/7 activity. In summary, these results demonstrate at the single-cell level that the temporal pattern of action potentials is critical for neuronal survival versus cell death fate during cortical development, besides the pro-survival effect of action potential firing per se.

Protease Hydrolysates Ameliorates Inflammation and Intestinal Flora Imbalance in DSS-Induced Colitis Mice

Wheat germ and fish skin usually has not been completely utilized and sometimes may be discarded, thus causing a lot of waste. Here, we aim at exploring the therapeutic anti-inflammatory effects of protease hydrolysates of wheat germ and fish skin on the ulcerative colitis (UC) mice. In the current study, wheat germ protein hydrolysates (WGPH) and fish skin gelatin hydrolysates (FSGH) treated mice had a longer colon than the DSS-induced mice. Moreover, protease hydrolysates reversed DSS-induced gut dysbiosis. Protease hydrolysates were likely to shift the balance of the intestinal flora on inflammation. In summary, these findings suggested that protease hydrolysates might serve as a latent therapy for UC treatment.

Isoform-Specific Effects of Apolipoprotein E on Markers of Inflammation and Toxicity in Brain Glia and Neuronal Cells In Vitro

Mutations to the cholesterol transport protein apolipoprotein E (ApoE) have been identified as a major risk factor for the development of sporadic or late-onset Alzheimer’s disease (AD), with the e4 allele representing an increased risk and the rare e2 allele having a reduced risk compared to the primary e3 form. The reasons behind the change in risk are not entirely understood, though ApoE4 has been connected to inflammation and toxicity in both the brain and the periphery. The goal of this study was to better understand how the ApoE isoforms (ApoE2/3/4) confer differential AD-related risk by assessing cell-specific ApoE-related neuroinflammatory and neurotoxic effects. We compared the effects of ApoE isoforms in vitro on human astrocytes, a human immortalized microglia cell line (HMC3), and the human neuroblastoma cell line SH-SY5Y. Cells were treated for 24 h with or without recombinant ApoE2, ApoE3, or ApoE4 (20 nM) and inflammation and toxicity markers assessed. Our results indicated the expression of inflammatory cytokines IL-1β, TNFα, and IL-6 in human astrocytes was increased in response to all ApoE isoforms, with ApoE4 evoking the highest level of cytokine expression. In response to ApoE2 or ApoE3, microglial cells showed reduced levels of microglial activation markers TREM2 and Clec7a, while ApoE4 induced increased levels of both markers. ApoE2 promoted neuron survival through increased BDNF release from astrocytes. In addition, ApoE2 promoted, while ApoE4 reduced, neuronal viability. Overall, these results suggest that ApoE4 acts on cells in the brain to promote inflammation and neuronal injury and that the deleterious effects of ApoE4 on these cells may, in part, contribute to its role as a risk factor for AD.

Neurotrophins as Key Regulators of Cell Metabolism: Implications for Cholesterol Homeostasis

Neurotrophins constitute a family of growth factors initially characterized as predominant mediators of nervous system development, neuronal survival, regeneration and plasticity. Their biological activity is promoted by the binding of two different types of receptors, leading to the generation of multiple and variegated signaling cascades in the target cells. Increasing evidence indicates that neurotrophins are also emerging as crucial regulators of metabolic processes in both neuronal and non-neuronal cells. In this context, it has been reported that neurotrophins affect redox balance, autophagy, glucose homeostasis and energy expenditure. Additionally, the trophic support provided by these secreted factors may involve the regulation of cholesterol metabolism. In this review, we examine the neurotrophins' signaling pathways and their effects on metabolism by critically discussing the most up-to-date information. In particular, we gather experimental evidence demonstrating the impact of these growth factors on cholesterol metabolism.

Modulatory effect of simvastatin on redox status, caspase-3 expression, p-protein kinase B (p-Akt), and brain-derived neurotrophic factor (BDNF) in an ethanol-induced neurodegeneration model

Neurodegenerative diseases are a common cause of morbidity and mortality worldwide, with oxidative stress, inflammation, and protein aggregation representing the main underlying mechanisms that ultimately lead to cell death. Ethanol has shown strong neurodegenerative consequences in experimental animal brains. Statins are a class of lipid-lowering drugs with many pleotropic effects. Therefore, the aim of the present study was to explore the modulatory effect of simvastatin (10 mg·kg-1·day-1) before and after the development of neurodegeneration (for 55 and 25 days, respectively) on redox state, caspase-3 expression, p-protein kinase B (p-Akt), and brain-derived neurotrophic factor (BDNF) in ethanol-induced (15% ethanol solution for 55 days) neurodegeneration. Seventy female Albino Swiss mice were included and randomly divided into five groups: C, control group; E, ethanol group; ES, group treated with simvastatin from the first day of ethanol intake; E + S, group treated with simvastatin after neurodegeneration development; and S, simvastatin group. Administration of simvastatin from the first day improved the biochemical changes, suppressed apoptosis, and induced autophagy and neurogenesis; however, its administration after the development of neurodegeneration resulted in partial improvement. The histopathological findings confirmed the biochemical changes. In conclusion, simvastatin has a neuroprotective effect against the development of ethanol-induced neurodegeneration and its progression.

Treatment efficacy of arterial urokinase thrombolysis combined with mechanical thrombectomy for acute cerebral infarction and its influence on neuroprotective factors and factors for neurological injury

OBJECTIVE

This study was designed to explore the treatment efficacy of arterial urokinase thrombolysis combined with Solitaire AB stent for acute cerebral infarction (ACI) and its influence on neuroprotective factors and factors for neurological injury.

METHODS

We randomly assigned 90 patients with ACI to receive arterial urokinase thrombolysis combined with Solitaire AB stent thrombectomy (observation group, OG) or to receive arterial urokinase thrombolysis (control group, CG). The two groups were compared in the National Institutes of Health Stroke Scale (NIHSS) score, activities of daily living (ADL) score, vascular recanalization rate 1 month after treatment, and serum levels of neuroprotective factors (insulin-like growth factor-I (IGF-1), neurotrophic factor (NTF), vascular endothelial growth factor (VEGF), and brain-derived neurotrophic factor (BDNF)) and factors for neurological injury (neuron-specific enolase (NSE), S100B protein (S100B), ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1), glial fibrillary acidic protein (GFAP)) before treatment and the day after treatment.

RESULTS

The overall treatment response rate and vascular recanalization rate 1 month after treatment were markedly higher in OG than in CG (P<0.05). The NIHSS score decreased and the ADL score in both groups increased after treatment, with a lower NIHSS score and a higher ADL score in OG than in CG (all P<0.001). The difference in the complication rate between the two groups was not statistically significant (P>0.05). The day after treatment, serum levels of IGF-1, NTF, VEGF, and BDNF in both groups increased while levels of NSE, S100B, UCH-L1, and GFAP in them decreased, with higher levels of IGF-1, NTF, VEGF, and BDNF, and lower levels of NSE, S100B, UCH-L1, and GFAP in OG than in CG (all P<0.05).

CONCLUSION

Arterial urokinase thrombolysis combined with Solitaire AB stent thrombectomy can enhance the treatment efficacy for ACI, stimulate the release of neuroprotective factors, and suppress the release of factors for neurological injury, without aggravating the treatment risk.

Synucleinopathy-associated pathogenesis in Parkinson's disease and the potential for brain-derived neurotrophic factor

The lack of disease-modifying treatments for Parkinson’s disease (PD) is in part due to an incomplete understanding of the disease’s etiology. Alpha-synuclein (α-syn) has become a point of focus in PD due to its connection to both familial and idiopathic cases—specifically its localization to Lewy bodies (LBs), a pathological hallmark of PD. Within this review, we will present a comprehensive overview of the data linking synuclein-associated Lewy pathology with intracellular dysfunction. We first present the alterations in neuronal proteins and transcriptome associated with LBs in postmortem human PD tissue. We next compare these findings to those associated with LB-like inclusions initiated by in vitro exposure to α-syn preformed fibrils (PFFs) and highlight the profound and relatively unique reduction of brain-derived neurotrophic factor (BDNF) in this model. Finally, we discuss the multitude of ways in which BDNF offers the potential to exert disease-modifying effects on the basal ganglia. What remains unknown is the potential for BDNF to mitigate inclusion-associated dysfunction within the context of synucleinopathy. Collectively, this review reiterates the merit of using the PFF model as a tool to understand the physiological changes associated with LBs, while highlighting the neuroprotective potential of harnessing endogenous BDNF.

Improvement of Cerebral Ischemia-Reperfusion Injury via Regulation of Apoptosis by Exosomes Derived from BDNF-Overexpressing HEK293

Brain-derived neurotrophic factor (BDNF) provides neuroprotective effects towards therapeutic cerebral ischemia-reperfusion (I/R) injury. This view has been proposed by more and more evidence. However, due to the lack of permeability of the blood-brain barrier (BBB) as well as the brief half-life in serum, clinical application is not widespread. To study the participation of exosomes containing BDNF in I/R, we isolated exosomes from BDNF-overexpressing HEK293. The protective outcomes of exosomes in hypoxia/reoxygenation (H/R) experiments were determined by the use of SY-5Y cells. Exosome-BDNF therapy restrained H/R-induced apoptosis by inhibition of the reducing levels of oxidative stress and calcium ions in the cells while maintaining stable levels of mitochondrial membrane potential in brain cells damaged by I/R. We then constructed a cerebral I/R injury model using SD rats to find the function of BDNF in exosome-mediated neuroprotection. The in vivo experiments conducted established that exosomes from BDNF-overexpressing HEK293 cells improved cerebral I/R injury by concealing neuronal apoptosis. Findings gained demonstrated that BDNF is a part of preventing cerebral I/R injury due to exosome mediation by regulating the cellular internal environment and inhibiting apoptosis.

Pentylenetetrazol-induced seizures in adult rats are associated with plastic changes to the dendritic spines on hippocampal CA1 pyramidal neurons

Epilepsy is a chronic neurobehavioral disorder whereby an imbalance between neurochemical excitation and inhibition at the synaptic level provokes seizures. Various experimental models have been used to study epilepsy, including that based on acute or chronic administration of Pentylenetetrazol (PTZ). In this study, a single PTZ dose (60 mg/kg) was administered to adult male rats and 30 min later, various neurobiological parameters were studied related to the transmission and modulation of excitatory impulses in pyramidal neurons of the hippocampal CA1 field. Rats experienced generalized seizures 1-3 min after PTZ administration, accompanied by elevated levels of Synaptophysin and Glutaminase. This response suggests presynaptic glutamate release is exacerbated to toxic levels, which eventually provokes neuronal death as witnessed by the higher levels of Caspase-3, TUNEL and GFAP. Similarly, the increase in PSD-95 suggests that viable dendritic spines are functional. Indeed, the increase in stubby and wide spines is likely related to de novo spinogenesis, and the regulation of neuronal excitability, which could represent a plastic response to the synaptic over-excitation. Furthermore, the increase in mushroom spines could be associated with the storage of cognitive information and the potentiation of thin spines until they are transformed into mushroom spines. However, the reduction in BDNF suggests that the activity of these spines would be down-regulated, may in part be responsible for the cognitive decline related to hippocampal function in patients with epilepsy.

Determining the Optimal Administration Conditions under Which MIF Exerts Neuroprotective Effects by Inducing BDNF Expression and Inhibiting Apoptosis in an In Vitro Stroke Model

Macrophage migration inhibitory factor (MIF) exerts neuroprotective effects against cerebral ischemia/reperfusion injury by inhibiting neuronal apoptosis and inducing the expression of brain-derived neurotrophic factor (BDNF). However, the optimal administration conditions of MIF are currently unknown. Here, we aimed to identify these conditions in an in vitro model. To determine the optimal concentration of MIF, human neuroblastoma cells were assigned to one of seven groups: control, oxygen and glucose deprivation/reperfusion (OGD/R), and OGD/R with different concentrations (1, 10, 30, 60, and 100 ng/mL) of MIF. Six groups were studied to investigate the optimal administration time: control, OGD/R, and OGD/R with MIF administered at different times (pre-OGD, OGD-treat, post-OGD, and whole-processing). Water-soluble tetrazolium salt-1 assay, Western blot analysis, and immunocytochemistry were used to analyze cell viability and protein expression. We found that 60 ng/mL was the optimal concentration of MIF. However, the effects of administration time were not significant; MIF elicited similar neuroprotective effects regardless of administration time. These findings correlated with the expression of BDNF and apoptosis-related proteins. This study provides detailed information on MIF administration, which offers a foundation for future in vivo studies and translation into novel therapeutic strategies for ischemic stroke.

Future Prospects of Gene Therapy for Friedreich's Ataxia

Friedreich's ataxia is an autosomal recessive neurogenetic disease that is mainly associated with atrophy of the spinal cord and progressive neurodegeneration in the cerebellum. The disease is caused by a GAA-expansion in the first intron of the frataxin gene leading to a decreased level of frataxin protein, which results in mitochondrial dysfunction. Currently, there is no effective treatment to delay neurodegeneration in Friedreich's ataxia. A plausible therapeutic approach is gene therapy. Indeed, Friedreich's ataxia mouse models have been treated with viral vectors en-coding for either FXN or neurotrophins, such as brain-derived neurotrophic factor showing promising results. Thus, gene therapy is increasingly consolidating as one of the most promising therapies. However, several hurdles have to be overcome, including immunotoxicity and pheno-toxicity. We review the state of the art of gene therapy in Friedreich's ataxia, addressing the main challenges and the most feasible solutions for them.

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.

Protocatechuic Acid Prevents Early Hour Ischemic Reperfusion Brain Damage by Restoring Imbalance of Neuronal Cell Death and Survival Proteins

OBJECTIVE

To investigate the neuroprotective effect of protocatechuic acid (PCA) on cell death/survival protein imbalance in a rat model of middle cerebral artery occlusion and reperfusion.

METHODS

Focal ischemia was induced by middle cerebral artery occlusion in adult male Wistar rats and confirmed by measuring infarction of brain by 2,3,5-Triphenyltetrazolium chloride (TTC) staining. Rats were treated with vehicle or PCA at 10, 30 or 50 mg/kg dose intraperitoneally and subjected to neurological deficits or beam walk assessment at 24 h of reperfusion. Effective dose of PCA (50 mg/kg) was administered at 1, 2 and 3 h time point of post-ictus ischemia. Cellular damage and nuclear condensation was observed by haematoxylin and eosin (H and E) staining and Hoechst 33342 staining respectively. Additionally, immunohistochemical expression of caspase 3 and cAMP-response element binding protein (CREB) and their mRNA's were observed.

RESULTS

PCA at 30 and 50 mg/kg significantly improved behavioural performance and reduced infarction. Maximum neuroprotective effect of PCA (50 mg/kg) was found at 1 h (early hours) post-ictus ischemia along with reduction in cellular damage and nuclear condensation. PCA increased CREB protein and it's mRNA, while suppressed caspase-3 protein and mRNA at 1 h of reperfusion injury.

CONCLUSION

PCA exhibit the potential to prevent early hour (1h) reperfusion injury restoring balance of survival and death protein may offer a cost effective adjuvant therapy in stroke.

Reduction in Nesfatin-1 Levels in the Cerebrospinal Fluid and Increased Nigrostriatal Degeneration Following Ventricular Administration of Anti-nesfatin-1 Antibody in Mice

Nesfatin-1 is one of several brain-gut peptides that have a close relationship with the central dopaminergic system. Our previous studies have shown that nesfatin-1 is capable of protecting nigral dopaminergic neurons against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity. A recent study also revealed a reduced blood level of nesfatin-1 in patients with Parkinson’s disease (PD). The current study was designed to investigate whether reduced nesfatin-1 in cerebrospinal fluid (CSF) induces nigrostriatal system degeneration. An intra-cerebroventricular (ICV) injection technique was used to administer anti-nesfatin-1 antibody directly into the lateral ventricle of the brain. Enzyme-linked immunosorbent assay (ELISA) results showed that ICV injection of anti-nesfatin-1 antibody into the lateral ventricle of the brain once daily for 2 weeks caused a significant reduction in nesfatin-1 levels in the CSF (93.1%). Treatment with anti-nesfatin-1 antibody resulted in a substantial loss (23%) of TH-positive (TH+) dopaminergic neurons in the substantia nigra pars compacta (SNpc), as shown by immunofluorescence staining, a depletion in dopamine and its metabolites in the striatum detected by high-performance liquid chromatography (HPLC), and obvious nuclear shrinkage and mitochondrial lesions in dopaminergic neurons in the SNpc detected by transmission electron microscopy (TEM). Furthermore, the results from our Western blot and ELISA experiments demonstrated that anti-nesfatin-1 antibody injection induced an upregulation of caspase-3 activation, increased the expression of p-ERK, and elevated brain-derived neurotrophic factor (BDNF) levels in the SNpc. Taken together, these observations suggest that reduced nesfatin-1 in the brain may induce nigrostriatal dopaminergic system degeneration; this effect may be mediated via mitochondrial dysfunction-related apoptosis. Our data support a role of nesfatin-1 in maintaining the normal physiological function of the nigrostriatal dopaminergic system.

Metabolism of Amino Acids in Cancer

Metabolic reprogramming has been widely recognized as a hallmark of malignancy. The uptake and metabolism of amino acids are aberrantly upregulated in many cancers that display addiction to particular amino acids. Amino acids facilitate the survival and proliferation of cancer cells under genotoxic, oxidative, and nutritional stress. Thus, targeting amino acid metabolism is becoming a potential therapeutic strategy for cancer patients. In this review, we will systematically summarize the recent progress of amino acid metabolism in malignancy and discuss their interconnection with mammalian target of rapamycin complex 1 (mTORC1) signaling, epigenetic modification, tumor growth and immunity, and ferroptosis. Finally, we will highlight the potential therapeutic applications.

Aerobic exercise improves VCI through circRIMS2/miR-186/BDNF-mediated neuronal apoptosis

BACKGROUND

Vascular cognitive impairment (VCI) is a common cognitive disorder caused by cerebrovascular disease, ranging from mild cognitive impairment to dementia. Studies have shown that aerobic exercise might alleviate the pathological development of VCI, and our previous study observed that aerobic exercise could alleviate VCI through NF-κB/miR-503/BDNF pathway. However, there are few studies on the mechanism. Therefore, it is of great significance to fill the gaps in the mechanism for the early diagnosis of VCI and the clinical prevention and treatment of vascular dementia.

METHODS

CircRNA microarray analysis and quantitative real-time PCR were used to detect the expression of circRNA regulating synaptic be exocytosis 2 (RIMS2) (circRIMS2). Cell apoptosis was determined by TdT-mediated dUTP nick-end labeling (TUNEL) assay. The dual-luciferase reporter assay was performed to verify the interaction between circRIMS2 and miR-186, as well as miR-186 and BDNF. RNA pull-down assay detected the binding between circRIMS2 and miR-186. A VCI mouse model was established by repeated ligation of bilateral common carotid arteries (2VO). The lentiviral interfering vector was injected into the VCI mice through the lateral ventricle. The mice in the aerobic exercise group performed 30 min (12 m/min) running for 5 days a week. A Morris water maze test was performed after 4 weeks.

RESULTS

The expression of circRIMS2 and BDNF in the serum of VCI patients was significantly reduced, miR-186 expression was increased, and the expression of circRIMS2 was increased in the 2VO group of mice undergoing aerobic exercise. The expression levels of circRIMS2 and BDNF in the oxygen and glucose deprivation-treated (OGD-treated) cells were decreased, the miR-186 expression and cell apoptosis were increased, while the effect was weakened after transfection with the lentiviral vector pLO-ciR-RIMS2. CircRIMS2 could bind to miR-186, and after interference with circRIMS2 in HT22 cells, the expression of miR-186 was increased. Besides, miR-186 could bind to BDNF, and BDNF expression was decreased because of the overexpression of miR-186 in HT22 cells. The expression level of BDNF in the pLO-ciR-RIMS2 group was increased, and apoptosis was decreased, but the miR-186 mimic weakened the effect of pLO-ciR-RIMS2. Aerobic exercise could shorten the average time that mice reached the platform in the Morris water maze, increase the expression level of circRIMS2 and BDNF, reduce miR-186 expression, and inhibit neuronal apoptosis. However, the interference with circRIMS2 weakened this effect.

CONCLUSION

The expression of circRIMS2 was down-regulated in VCI and aerobic exercise reduced neuronal apoptosis, and circRIMS2 improved VCI through the circRIMS2/miR-186/BDNF axis.

Curcumin protects rat hippocampal neurons against pseudorabies virus by regulating the BDNF/TrkB pathway

Pseudorabies virus (PRV) infection can elicit nervous system disorders. Curcumin has been reported to have neuroprotective effects. However, whether curcumin can protect neurons against PRV infection and the underlying mechanisms remain unclear. In the present study, for the first time, the protective effects of curcumin against PRV-induced oxidative stress, apoptosis, and mitochondrial dysfunction in rat hippocampal neurons and the brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB) pathway were investigated. Results indicated that PRV with a titer of 3.06 × 10⁶ TCID50 (50% tissue culture infective dose) induced oxidative damage of hippocampal neurons 2 h post-infection and that 10 μM curcumin improved the viability of PRV-infected hippocampal neurons. Blocking the BDNF/TrkB pathway reversed the neuroprotective effects of curcumin, which were imparted by decreasing the PRV-induced upregulation of nitric oxide synthase expression, repressing the PRV-activated mitochondrial apoptotic pathway, and mitochondrial dysfunction. To conclude, curcumin exhibited a neuroprotective role against PRV infection by upregulating the BDNF/TrkB pathway. This study provides insight into the anti-PRV neuroprotective application of curcumin and the underlying mechanism in the prophylaxis and treatment of neurological disorders caused by PRV infection.

Evolution of BDNF serum levels during the first six months after alcohol withdrawal

OBJECTIVES

Brain-Derived Neurotrophic Factor (BDNF) has been associated with alcohol dependence and appear to vary after withdrawal, although the link with the withdrawal outcome on the long term is unknown. We aimed to assess the evolution of BDNF levels during the six months following withdrawal and determine the association with the status of alcohol consumption.

METHODS

Serum BDNF levels of alcohol-dependent patients (n = 248) and biological and clinical parameters were determined at the time of alcohol cessation (D0), 14 days (D14), 28 days (D28), and 2, 4, and 6 months after (M2, M4, M6).

RESULTS

Abstinence decreased during follow-up and was 31.9% after six months. BDNF levels increased by 14 days after withdrawal and remained elevated throughout the six-month period, independently of alcohol consumption. Serum BDNF levels evolved over time (p < 0.0001), with a correlation between BDNF and GGT levels. The prescription of baclofen at the time of withdrawal was associated with higher serum BDNF levels throughout the follow-up and that of anti-inflammatory drugs with lower BDNF levels.

CONCLUSIONS

A link between BDNF levels, liver function, and the inflammatory state in the context of alcohol abuse and not only with alcohol dependence itself is proposed.

BDNF levels and liver stiffness in subjects with alcohol use disorder: Evaluation after alcohol withdrawal

Background: Brain-derived neurotrophic factor (BDNF) plays a key role in the processes of withdrawal and addiction in alcohol use disorder (AUD), and is also involved in liver homeostasis. The role of BDNF in liver damage and its link with liver stiffness are not known. We hypothesize that serum BDNF levels are linked to changes in hepatic elasticity, both of which depend on variations in alcohol consumption.Objectives: We aimed to study the evolution of BDNF levels and changes in the liver stiffness (LS) of AUD subjects, within two months following withdrawal.Methods: We measured LS by FibroScan® (as an indicator of the degree of liver fibrosis), gamma glutamyl transferase (GGT) levels (as a nonspecific but sensitive marker of liver status) and serum BDNF levels of 62 alcohol-dependent subjects without previously identified liver complications. Measures were obtained at the time of withdrawal (M0) and two months later (M2). Results: BDNF levels increased after alcohol withdrawal and small variations of LS were observed. BDNF values increased significantly according to fibrosis stages measured by LS (p = .028 at M0), and were predicted by GGT levels in a regression model (p = .007 at M0 and p = .003 at M2).Conclusion: In AUD, BDNF levels were associated with measured LS when divided into fibrosis risk categories. Changes in LS and BDNF levels after alcohol withdrawal may be related to changes in homeostatic mechanisms, in addition to those of liver status.

Amitriptyline Protects Against Lidocaine-induced Neurotoxicity in SH-SY5Y Cells via Inhibition of BDNF-mediated Autophagy

Amitriptyline (AMI) is a traditional tricyclic antidepressant that has been proven to exhibit neuroprotective effects in various neurological disorders. However, the underlying mechanism by which AMI attenuates lidocaine-induced neurotoxicity remains poorly understood. Brain-derived neurotrophic factor (BDNF) is an essential neurotrophin to neuronal development and survival in the brain, and recent studies have suggested that BDNF plays an important role in mediating lidocaine-induced neurotoxicity. The present study was performed to evaluate the protective effect of AMI against the neurotoxicity induced by lidocaine and to explore the role of BDNF-dependent autophagy in this process. The data showed that AMI pretreatment alleviated lidocaine-induced neurotoxicity, as evidenced by the restoration of cell viability, normalization of cell morphology, and reduction in the cell apoptosis index. In addition, autophagy inhibitor 3-methyladenine (3-MA) had a protective effect similar to that of AMI, but autophagy activator rapamycin eliminated the protective effect of AMI by suppressing mTOR activation. Moreover, at the molecular level, we found that AMI-mediated autophagy was involved in the expression of BDNF. The overexpression of BDNF or application of exogenous recombinant BDNF significantly suppressed autophagy and protected SH-SY5Y cells from apoptosis induced by Lido, whereas the neuroprotection of AMI was abolished by either knockdown of BDNF or use of a tropomyosin-related kinase B (TrkB) inhibitor ANA-12 in SH-SY5Y cells. Overall, our findings demonstrated that the protective effect of AMI against lidocaine-induced neurotoxicity correlated with inhibition of autophagy activity through upregulation of BDNF expression.