The role of neurotrophins during early development

The Influence of Neurotrophins on the Brain-Lung Axis: Conception, Pregnancy, and Neonatal Period

Neurotrophins (NTs) are four small proteins produced by both neuronal and non-neuronal cells; they include nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4). NTs can exert their action through both genomic and non-genomic mechanisms by interacting with specific receptors. Initial studies on NTs have identified them only as functional molecules of the nervous system. However, recent research have shown that some tissues and organs (such as the lungs, skin, and skeletal and smooth muscle) as well as some structural cells can secrete and respond to NTs. In addition, NTs perform several roles in normal and pathological conditions at different anatomical sites, in both fetal and postnatal life. During pregnancy, NTs are produced by the mother, placenta, and fetus. They play a pivotal role in the pre-implantation process and in placental and embryonic development; they are also involved in the development of the brain and respiratory system. In the postnatal period, it appears that NTs are associated with some diseases, such as sudden infant death syndrome (SIDS), asthma, congenital central hypoventilation syndrome (CCHS), and bronchopulmonary dysplasia (BPD).

Biology and pathophysiology of symptomatic neuromas

ABSTRACT

Neuromas are a substantial cause of morbidity and reduction in quality of life. This is not only caused by a disruption in motor and sensory function from the underlying nerve injury but also by the debilitating effects of neuropathic pain resulting from symptomatic neuromas. A wide range of surgical and therapeutic modalities have been introduced to mitigate this pain. Nevertheless, no single treatment option has been successful in completely resolving the associated constellation of symptoms. While certain novel surgical techniques have shown promising results in reducing neuroma-derived and phantom limb pain, their effectiveness and the exact mechanism behind their pain-relieving capacities have not yet been defined. Furthermore, surgery has inherent risks, may not be suitable for many patients, and may yet still fail to relieve pain. Therefore, there remains a great clinical need for additional therapeutic modalities to further improve treatment for patients with devastating injuries that lead to symptomatic neuromas. However, the molecular mechanisms and genetic contributions behind the regulatory programs that drive neuroma formation-as well as the resulting neuropathic pain-remain incompletely understood. Here, we review the histopathological features of symptomatic neuromas, our current understanding of the mechanisms that favor neuroma formation, and the putative contributory signals and regulatory programs that facilitate somatic pain, including neurotrophic factors, neuroinflammatory peptides, cytokines, along with transient receptor potential, and ionotropic channels that suggest possible approaches and innovations to identify novel clinical therapeutics.

Greater maltreatment severity is associated with smaller brain volume with implication for intellectual ability in young children

Background

Childhood maltreatment profoundly alters trajectories of brain development, promoting markedly increased long-term health risks and impaired intellectual development. However, the immediate impact of maltreatment on brain development in children and the extent to which altered global brain volume contributes to intellectual development in children with maltreatment experience is currently unknown. We here utilized MRI data obtained from children within 6 months after the exposure to maltreatment to assess the association of maltreatment severity with global brain volume changes. We further assessed the association between maltreatment severity and intellectual development and tested for the mediating effect of brain volume on this association.

Method

We used structural MRI (3T) in a sample of 49 children aged 3-5 years with maltreatment exposure, i.e. emotional and physical abuse and/or neglect within 6 months, to characterize intracranial and tissue-specific volumes. Maltreatment severity was coded using the Maternal Interview for the Classification of Maltreatment. IQ was tested at study entry and after one year using the Snijders Oomen Nonverbal Test.

Results

Higher maltreatment severity was significantly correlated with smaller intracranial volume (r = -.393, p = .008), which was mainly driven by lower total brain volume (r = -.393, p = .008), which in turn was primarily due to smaller gray matter volume (r = -.454, p = .002). Furthermore, smaller gray matter volume was associated with lower IQ at study entry (r = -.548, p < .001) and predicted IQ one year later (r = -.493, p = .004.). The observed associations were independent of potential confounding variables, including height, socioeconomic status, age and sex.

Importance

We provide evidence that greater maltreatment severity in early childhood is related to smaller brain size at a very young age with significant consequences for intellectual ability, likely setting a path for far-reaching long-term disadvantages. Insights into the molecular and neural processes that underlie the impact of maltreatment on brain structure and function are urgently needed to derive mechanism-driven targets for early intervention.

Off-target pharmacological activity at various kinases: Potential functional and pathological side effects

In drug discovery, during the lead optimization and candidate characterization stages, novel small molecules are frequently evaluated in a battery of in vitro pharmacology assays to identify potential unintended, off-target interactions with various receptors, transporters, ion channels, and enzymes, including kinases. Furthermore, these screening panels may also provide utility at later stages of development to provide a mechanistic understanding of unexpected safety findings. Here, we present a compendium of the most likely functional and pathological outcomes associated with interaction(s) to a panel of 95 kinases based on an extensive curation of the scientific literature. This panel of kinases was designed by AbbVie based on safety-related data extracted from the literature, as well as from over 20 years of institutional knowledge generated from discovery efforts. For each kinase, the scientific literature was reviewed using online databases and the most often reported functional and pathological effects were summarized. This work should serve as a practical guide for small molecule drug discovery scientists and clinical investigators to predict and/or interpret adverse effects related to pharmacological interactions with these kinases.

Neurotrophins: Expression of Brain-Lung Axis Development

Neurotrophins (NTs) are a group of soluble growth factors with analogous structures and functions, identified initially as critical mediators of neuronal survival during development. Recently, the relevance of NTs has been confirmed by emerging clinical data showing that impaired NTs levels and functions are involved in the onset of neurological and pulmonary diseases. The alteration in NTs expression at the central and peripheral nervous system has been linked to neurodevelopmental disorders with an early onset and severe clinical manifestations, often named "synaptopathies" because of structural and functional synaptic plasticity abnormalities. NTs appear to be also involved in the physiology and pathophysiology of several airway diseases, neonatal lung diseases, allergic and inflammatory diseases, lung fibrosis, and even lung cancer. Moreover, they have also been detected in other peripheral tissues, including immune cells, epithelium, smooth muscle, fibroblasts, and vascular endothelium. This review aims to provide a comprehensive description of the NTs as important physiological and pathophysiological players in brain and lung development.

Levels of Neurospecific Peptides, Neurotransmitters and Neuroreceptor Markers in the Serum of Children with Various Sensory Disorders, Mild Cognitive Impairments and Other Neuropathology

Background. The role of recently discovered neurospecific peptides in the pathogenesis of acute and progressive neurologic disorders, their neuroprotective features, and possibilities to use them as markers for the course and prognosis of certain diseases have been actively studied in recent decades. However, neurospecific peptides are almost not studied in chronic residual diseases. In our study we measured the levels of neurospecific peptides and some other markers to achieve understanding of general neurophysiological trends in congenital and acquired chronic non-progressive brain pathology with reference to the selection of relevant groups — study objects. Objective. The aim of the study is to study patterns of neurospecific peptides, neurotransmitters and neuroreceptor markers distribution in the serum of children with various pathogenetic variants of chronic neuropathology. Methods. The study included children from 3 to 16 years old with different pathologies. The sample was divided into groups by pathology type: no sensory and neurological disorders, congenital sensory deficit due to mutation of genes expressed and not expressed in the brain, early acquired sensory deficit of multifactorial nature, congenital mild and severe organic disorders of central nervous system (CNS) in residual stage without baseline sensory deficit, acquired functional CNS disorders without baseline organic defect and sensory deficit. The following laboratory data (neurophysiological components) was studied: nerve growth factor, brain-derived neurotropic factor, neurotrophin-3, neurotrophin-4, neuregulin-1-beta-1, beta-secretase, sirtuin-1, synaptophysin, neuronal nitric oxide synthase, and anti-NR2 glutamate receptor antibodies. The parameters of cognitive activity, sense of vision, sense of smell, and acoustic sense were also evaluated. Results. The study included 274 participants. Neuropeptides and markers have shown a variable degree and range in the group spectrum of differences from normal levels. The most variable in the examined sample was NO-synthase, as well as levels of both neurotrophins, beta-secretase, and glutamate receptor marker. All visual deficits were associated with increased NO-synthase levels (p < 0.001). Neuroplasticity peptides (beta-secretase, neurotrophin-3 and 4) have been activated in all pathological conditions. Nerve growth factor and brain-derived neurotropic factor were specifically activated in mild organic CNS lesions (mild cognitive impairments), while neuregulin — in congenital genetically determined visual deficits. There was no specific activation of neuropeptides and NO-synthase level tended to decrease in cases of severe CNS lesions. Conclusion. The study results suggest that all types of early visual impairment are associated with increased physiological neuronal activity, and non-organic neurological functional disorders — mainly with increased physiological synaptic activity. General neuroplasticity processes were activated in all cases of visual deficits but more specific. However, more specific and well-studied processes were activated in mild organic CNS lesions, and neuroplasticity processes did not activate adequately in severe organic CNS lesions probably due to the limited neuronal and synaptic resources.

Interactions Among Brain-Derived Neurotrophic Factor and Neuroimmune Pathways Are Key Components of the Major Psychiatric Disorders

The purpose of this review is to summarize the current knowledge regarding the reciprocal associations between brain-derived neurotrophic factor (BDNF) and immune-inflammatory pathways and how these links may explain the involvement of this neurotrophin in the immune pathophysiology of mood disorders and schizophrenia. Toward this end, we delineated the protein-protein interaction (PPI) network centered around BDNF and searched PubMed, Scopus, Google Scholar, and Science Direct for papers dealing with the involvement of BDNF in the major psychosis, neurodevelopment, neuronal functions, and immune-inflammatory and related pathways. The PPI network was built based on the significant interactions of BDNF with neurotrophic (NTRK2, NTF4, and NGFR), immune (cytokines, STAT3, TRAF6), and cell-cell junction (CTNNB, CDH1) DEPs (differentially expressed proteins). Enrichment analysis shows that the most significant terms associated with this PPI network are the tyrosine kinase receptor (TRKR) and Src homology region two domain-containing phosphatase-2 (SHP2) pathways, tyrosine kinase receptor signaling pathways, positive regulation of kinase and transferase activity, cytokine signaling, and negative regulation of the immune response. The participation of BDNF in the immune response and its interactions with neuroprotective and cell-cell adhesion DEPs is probably a conserved regulatory process which protects against the many detrimental effects of immune activation and hyperinflammation including neurotoxicity. Lowered BDNF levels in mood disorders and schizophrenia (a) are associated with disruptions in neurotrophic signaling and activated immune-inflammatory pathways leading to neurotoxicity and (b) may interact with the reduced expression of other DEPs (CTNNB1, CDH1, or DISC1) leading to multiple aberrations in synapse and axonal functions.

Chronic stress and Alzheimer's disease: the interplay between the hypothalamic-pituitary-adrenal axis, genetics and microglia

Chronic psychosocial stress is increasingly being recognised as a risk factor for sporadic Alzheimer's disease (AD). The hypothalamic-pituitary-adrenal axis (HPA axis) is the major stress response pathway in the body and tightly regulates the production of cortisol, a glucocorticoid hormone. Dysregulation of the HPA axis and increased levels of cortisol are commonly found in AD patients and make a major contribution to the disease process. The underlying mechanisms remain poorly understood. In addition, within the general population there are interindividual differences in sensitivities to glucocorticoid and stress responses, which are thought to be due to a combination of genetic and environmental factors. These differences could ultimately impact an individuals' risk of AD. The purpose of this review is first to summarise the literature describing environmental and genetic factors that can impact an individual's HPA axis reactivity and function and ultimately AD risk. Secondly, we propose a mechanism by which genetic factors that influence HPA axis reactivity may also impact inflammation, a key driver of neurodegeneration. We hypothesize that these factors can mediate glucocorticoid priming of the immune cells of the brain, microglia, to become pro-inflammatory and promote a neurotoxic environment resulting in neurodegeneration. Understanding the underlying molecular mechanisms and identifying these genetic factors has implications for evaluating stress-related risk/progression to neurodegeneration, informing the success of interventions based on stress management and potential risks associated with the common use of glucocorticoids.

Correlations between serum BDNF levels and neurodevelopmental outcomes in infants of mothers with gestational diabetes

BACKGROUND

Diabetes during pregnancy is associated with an increased risk of foetal and neonatal complications and long-term complications in the offspring. Brain-derived neurotrophic factor (BDNF), a neurotrophin that has a crucial role in neurogenesis modulation and neural pathway maturation during neurodevelopment, may have a role in protecting neurons against injury and diseases by modulating glucose metabolism. The aim of this study was to investigate the possible relationship between the serum BDNF levels of infants of mothers with gestational diabetes (IMGD) and neurodevelopmental outcomes of the children after birth.

METHODS

A total of 24 candidates, including 8 IMGD and 16 healthy infants, were recruited for the study. Medical records were reviewed. Serum BDNF levels of the study participants were collected at birth and at 6 and 12 months of age. Developmental outcomes of each candidate were assessed using the Bayley Scales of Infant Development III (BSID III) at 6 and 12 months of corrected age.

RESULTS

Compared to non-IMGD, IMGD had greater mean body weight (p = 0.04) and height (p < 0.01) at age 12 months. The language composite score was significantly lower in IMGD at 12 months of age (p = 0.038). The BDNF content was significantly higher in the non-IMGD than in the IMGD group at 12 months of age (p = 0.013).

CONCLUSION

In this study, we demonstrated that infants of mothers with gestational diabetes do worse in language development and have lower BDNF levels at 12 months of age. There may be a close correlation between language outcomes and serum BDNF levels at 12 months of age. A follow-up study on future developmental status is warranted.

The Influence of Vitamin D Intake and Status on Mental Health in Children: A Systematic Review

A potential role of vitamin D in some components of mental health is currently suggested, but the analyses are conducted mainly for adults, while for young individuals mental health is especially important, due to its lifelong effects. The aim of the study was to analyze the association between vitamin D intake or status and mental health in children within a systematic review of literature, including both intervention and observational studies. The literature search was conducted according to the PRISMA guidelines and it covered peer-reviewed studies included in databases of PubMed and Web of Science until October 2019. The studies presenting either vitamin D intake, or vitamin D status in human subjects were allowed (excluding subjects with intellectual disabilities, eating disorders and neurological disorders), while for mental health the various methods of assessment and wide scope of factors were included. The bias was assessed using the Newcastle-Ottawa Scale (NOS). The review was registered in the PROSPERO database (CRD42020155779). A number of 7613 studies after duplicate removing were extracted by two independent researchers, followed by screening and assessment for eligibility, conducted by two independent researchers in two steps (based on title and abstract). Afterwards, the full texts were obtained and after reviewing, a number of 24 studies were included. The synthetic description of the results was prepared, structured around exposure (vitamin D supplementation/status) and outcome (components of mental health). The included studies were conducted either in groups of healthy individuals, or individuals with mental health problems, and they assessed following issues: behavior problems, violence behaviors, anxiety, depressive symptoms/depression, aggressive disorder, psychotic features, bipolar disorder, obsessive compulsive disorder, suicidal incident, as well as general patterns, as follows: mental health, level of distress, quality of life, well-being, mood, sleep patterns. The vast majority of assessed studies, including the most prominent ones (based on the NOS score) supported potential positive influence of vitamin D on mental health in children. As a limitation of the analysis, it should be indicated that studies conducted so far presented various studied groups, outcomes and psychological measures, so more studies are necessary to facilitate comparisons and deepen the observations. Nevertheless, vitamin D intake within a properly balanced diet or as a supplementation, except for a safe sun exposure, should be indicated as an element supporting mental health in children, so it should be recommended to meet the required 25(OH)cholecalciferol blood level in order to prevent or alleviate mental health problems.

Neurotrophic factors and their receptors in lung development and implications in lung diseases

Although lung innervation has been described by many studies in humans and rodents, the regulation of the respiratory system induced by neurotrophins is not fully understood. Here, we review current knowledge on the role of neurotrophins and the expression and function of their receptors in neurogenesis, vasculogenesis and during the embryonic development of the respiratory tree and highlight key implications relevant to respiratory diseases.

A comprehensive review on chlorpyrifos toxicity with special reference to endocrine disruption: Evidence of mechanisms, exposures and mitigation strategies

Chlorpyrifos (CPF) is a broad-spectrum chlorinated organophosphate (OP) pesticide used for the control of a variety of insects and pathogens in crops, fruits, vegetables, as well as households, and various other locations. The toxicity of CPF has been associated with neurological dysfunctions, endocrine disruption, and cardiovascular diseases (CVDs). It can also induce developmental and behavioral anomalies, hematological malignancies, genotoxicity, histopathological aberrations, immunotoxicity, and oxidative stress as evidenced by animal modeling. Moreover, eye irritation and dermatological defects are also reported due to CPF toxicity. The mechanism of action of CPF involves blocking the active sites of the enzyme, acetylcholinesterase (AChE), thereby producing adverse nervous system effects. Although CPF has low persistence in the body, its active metabolites, 3,5,6-trichloro-2-pyridinol (TCP), and chlorpyrifos-oxon (CPO) are comparatively more persistent, albeit equally toxic, and thus produce serious health complications. The present review has been compiled taking into account the work related to CPF toxicity and provides a brief compilation of CPF-induced defects in animals and humans, emphasizing the abnormalities leading to endocrine disruption, neurotoxicity, reproductive carcinogenesis, and disruptive mammary gland functionality. Moreover, the clinical signs and symptoms associated with the CPF exposure along with the possible pharmacological treatment are reported in this treatise. Additionally, the effect of food processing methods in reducing CPF residues from different agricultural commodities and dietary interventions to curtail the toxicity of CPF has also been discussed.

Hyperbaric oxygen therapy mobilized circulating stem cells and improved delayed encephalopathy after acute carbon monoxide poisoning with up-regulation of brain-derived neurotrophic factor

Background Delayed encephalopathy (DE) is the most severe complication after acute carbon monoxide (CO) poisoning, which seriously affects the outcome of patients and leads to a high disability rate. Prior studies have shown that hyperbaric oxygen (HBO₂) therapy is therapeutic for DE due to reducing immune-mediated neuropathology and thus improving cognitive performance. Methods In our present perspective study, five DE patients were treated regularly with HBO₂ therapy. The mini-mental state examination (MMSE) and Barthel index (BI) were intermittently collected during their hospitalization for mental and physical status evaluation, the peripheral bloods were serially sampled to determine the concentration changes of circulating stem cells, as well as corresponding BDNF and neural markers. Results MMSE and BI showed series of improvements after multiple HBO₂ therapies. The CD34⁺/CD90⁺ and CD34⁺/CD133⁺ dual positive cells, which were categorized as circulating stem cells, were observed an overall up-regulation since the beginning of the DE onset upon the application of HBO₂ therapy. Characteristic neurotrophin BDNF, neural markers such as nestin and synaptophysin (SYP) were also up-regulated after exposure of HBO₂. Conclusion The application of HBO₂ therapy is of significance in improving the cognition of DE patients, along with mobilized circulating stem cells. We primarily infer that the CD34⁺/CD90⁺ and CD34⁺/CD133⁺ cells were mobilized by HBO₂ exposure and have played a positive role in cognition improvement on DE patients by up-regulation of BDNF, nestin and SYP. The altering amount of circulating stem cells mobilized in peripheral blood could be a potential marker on predicting the outcome of DE.

The impact of trophic and immunomodulatory factors on oligodendrocyte maturation: Potential treatments for encephalopathy of prematurity

Encephalopathy of prematurity (EoP) is a major cause of morbidity in preterm neonates, causing neurodevelopmental adversities that can lead to lifelong impairments. Preterm birth-related insults, such as cerebral oxygen fluctuations and perinatal inflammation, are believed to negatively impact brain development, leading to a range of brain abnormalities. Diffuse white matter injury is a major hallmark of EoP and characterized by widespread hypomyelination, the result of disturbances in oligodendrocyte lineage development. At present, there are no treatment options available, despite the enormous burden of EoP on patients, their families, and society. Over the years, research in the field of neonatal brain injury and other white matter pathologies has led to the identification of several promising trophic factors and cytokines that contribute to the survival and maturation of oligodendrocytes, and/or dampening neuroinflammation. In this review, we discuss the current literature on selected factors and their therapeutic potential to combat EoP, covering a wide range of in vitro, preclinical and clinical studies. Furthermore, we offer a future perspective on the translatability of these factors into clinical practice.

Role of neurotrophins in pregnancy and offspring brain development

Neurotrophins are a family of functionally and structurally related proteins which play a key role in the survival, development, and function of neurons in both the central and peripheral nervous systems. Brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4) are the family members of neurotrophins. Neurotrophins play a crucial role in influencing the development of the brain and learning and memory processes. Studies demonstrate that they also play crucial role in influencing reproductive and immune systems. Neurotrophins have been shown to influence various processes in the mother, placenta, and fetus during pregnancy. Development and maturation of feto-placental unit and the fetal growth trajectories are influenced by neurotrophins. In addition to neurotrophins, neuropeptides like neuropeptide Y also play a crucial role during various processes of pregnancy and during fetal brain development. Neurotrophins have also been shown to have a cross talk with various angiogenic factors and influence placental development. Alterations in the levels of neurotrophins and neuropeptides lead to placental pathologies resulting in various pregnancy complications like preeclampsia, intrauterine growth restriction and preterm births. Studies in animals have reported low levels of maternal micronutrients like folic acid, vitamin B₁₂ and omega-3 fatty acids influence brain neurotrophins resulting in impaired cognitive functioning in the offspring. Maternal nutrition is also known to affect the expression of neuropeptides. It is essential to understand the role of various neurotrophins across various stages of pregnancy and its relationship with neurodevelopmental outcomes in children. This will lead to early prediction of poor neurodevelopmental outcomes. The present review describes evidence describing the role of neurotrophins in determining pregnancy outcome and altered neurodevelopment in the offspring. The possible mechanism through which maternal nutrition influences neurotrophins and neuropeptides to regulate offspring brain development and function is also discussed.

Brain-derived neurotrophic factor and nerve growth factor concentrations in maternal and umbilical cord blood of opium-addicted mothers

BACKGROUND

It is reported that opium consumption during pregnancy is associated with adverse pregnancy outcomes and neurodevelopmental defects in infants. BDNF and NGF alterations during pregnancy cause neurobehavioral deficits in the offspring. The aim of this study was to investigate the effect of opium addiction of pregnant women on BDNF and NGF levels in maternal and umbilical cord blood as well as pregnancy outcome.

MATERIALS AND METHODS

The present research was a cross-sectional study. Thirty-five addicted pregnant women and 35 healthy pregnant women were included in the study. Blood samples were taken immediately after delivery from the maternal vein and umbilical cord. Then, BDNF and NGF concentrations in serum were measured by ELISA kits. The outcomes of pregnancy were determined by a checklist. Descriptive, t test, Mann-Whitney, and Chi-squared test were used to analyze the data. SPSS version 21 software was used for the analyses. A p-value <.05 was considered significant.

RESULTS

BDNF levels were significantly lower in maternal and umbilical cord blood in the opium-addicted group (917.2 31 ± 316.5 and 784.6 ± 242.9 pg/ml, respectively) compared to the control group (1351 ± 375 and 1063 ± 341 pg/ml, respectively) (p < .0001 and p < .0002, respectively). Similarly, NGF level was significantly lower in maternal and umbilical cord blood in the opium-addicted group (302.7 ± 35.50 and 226.6 ± 45.43 pg/ml, respectively) compared to the control group (345.7 ± 43.16 and 251.2 ± 37.72 pg/ml, respectively) (p < .0001 and p = .0165, respectively). Adverse pregnancy outcomes such as NICU admissions, congenital anomalies, neonatal deaths, meconium contaminated amniotic fluid, respiratory problems, neonatal resuscitation, and low Apgar score were significantly higher in the opium-addicted group than in the control group.

CONCLUSION

The results of this study revealed that opium consumption during pregnancy reduces BDNF and NGF levels in maternal and umbilical cord blood, which may cause neurodevelopmental disorders in later periods of infants' life.

Hormonal Regulation of Mammalian Adult Neurogenesis: A Multifaceted Mechanism

Adult neurogenesis—resulting in adult-generated functioning, integrated neurons—is still one of the most captivating research areas of neuroplasticity. The addition of new neurons in adulthood follows a seemingly consistent multi-step process. These neurogenic stages include proliferation, differentiation, migration, maturation/survival, and integration of new neurons into the existing neuronal network. Most studies assessing the impact of exogenous (e.g., restraint stress) or endogenous (e.g., neurotrophins) factors on adult neurogenesis have focused on proliferation, survival, and neuronal differentiation. This review will discuss the multifaceted impact of hormones on these various stages of adult neurogenesis. Specifically, we will review the evidence for hormonal facilitation (via gonadal hormones), inhibition (via glucocorticoids), and neuroprotection (via recruitment of other neurochemicals such as neurotrophin and neuromodulators) on newly adult-generated neurons in the mammalian brain.

An integrative approach for pediatric auditory neuropathy spectrum disorders: revisiting etiologies and exploring the prognostic utility of auditory steady-state response

Auditory neuropathy is an important entity in childhood sensorineural hearing loss. Due to diverse etiologies and clinical features, the management is often challenging. This study used an integrative patient-history, audiologic, genetic, and imaging-based approach to investigate the etiologies and audiologic features of 101 children with auditory neuropathy. Etiologically, 48 (47.5%), 16 (15.8%), 11 (10.9%), and 26 (25.7%) children were categorized as having acquired, genetic, cochlear nerve deficiency-related, and indefinite auditory neuropathy, respectively. The most common causes of acquired and genetic auditory neuropathy were prematurity and OTOF mutations, respectively. Patients with acquired auditory neuropathy presented hearing loss earlier (odds ratio, 10.2; 95% confidence interval, 2.2–47.4), whereas patients with genetic auditory neuropathy had higher presence rate of distortion product otoacoustic emissions (odds ratio, 10.7; 95% confidence interval, 1.3–85.4). In patients with different etiologies or pathological sites, moderate to strong correlations (Pearson’s r = 0.51–0.83) were observed between behavioral thresholds and auditory steady-state response thresholds. In conclusion, comprehensive assessments can provide etiological clues in ~75% of the children with auditory neuropathy. Different etiologies are associated with different audiologic features, and auditory steady-state responses might serve as an objective measure for estimating behavioral thresholds.

Neuroprotective strategies following perinatal hypoxia-ischemia: Taking aim at NOS

Perinatal asphyxia is characterized by oxygen deprivation and lack of perfusion in the perinatal period, leading to hypoxic-ischemic encephalopathy and sequelae such as cerebral palsy, mental retardation, cerebral visual impairment, epilepsy and learning disabilities. On cellular level PA is associated with a decrease in oxygen and glucose leading to ATP depletion and a compromised mitochondrial function. Upon reoxygenation and reperfusion, the renewed availability of oxygen gives rise to not only restoration of cell function, but also to the activation of multiple detrimental biochemical pathways, leading to secondary energy failure and ultimately, cell death. The formation of reactive oxygen species, nitric oxide and peroxynitrite plays a central role in the development of subsequent neurological damage. In this review we give insight into the pathophysiology of perinatal asphyxia, discuss its clinical relevance and summarize current neuroprotective strategies related to therapeutic hypothermia, ischemic postconditioning and pharmacological interventions. The review will also focus on the possible neuroprotective actions and molecular mechanisms of the selective neuronal and inducible nitric oxide synthase inhibitor 2-iminobiotin that may represent a novel therapeutic agent for the treatment of hypoxic-ischemic encephalopathy, both in combination with therapeutic hypothermia in middle- and high-income countries, as well as stand-alone treatment in low-income countries.

Neuroanatomical distribution and functions of brain-derived neurotrophic factor in zebrafish (Danio rerio) brain

Brain-derived neurotrophic factor (BDNF) is an extensively studied protein that is evolutionarily conserved and widely distributed in the brain of vertebrates. It acts via its cognate receptors TrkB and p75^NTR and plays a central role in the developmental neurogenesis, neuronal survival, proliferation, differentiation, synaptic plasticity, learning and memory, adult hippocampal neurogenesis, and brain regeneration. BDNF has also been implicated in a plethora of neurological disorders. Hence, understanding the processes that are controlled by BDNF and their regulating mechanisms is important. Although, BDNF has been thoroughly studied in the mammalian models, contradictory effects of its functions have been reported on several occasions. These contradictory effects may be attributed to the sheer complexity of the mammalian brain. The study of BDNF and its associated functions in a simpler vertebrate model may provide some clarity about the effects of BDNF on the neurophysiology of the brain. Keeping that in mind, this review aims at summarizing the current knowledge about the distribution of BDNF and its associated functions in the zebrafish brain. The main focus of the review is to give a comparative overview of BDNF distribution and function in zebrafish and mammals with respect to distinct life stages. We have also reviewed the regulation of bdnf gene in zebrafish and discussed its role in developmental and adult neurogenesis.

Nerves and Pancreatic Cancer: New Insights into a Dangerous Relationship

Perineural invasion (PNI) is defined as the presence of neoplastic cells along nerves and/or within the different layers of nervous fibers: epineural, perineural and endoneural spaces. In pancreatic cancer-particularly in pancreatic ductal adenocarcinoma (PDAC)-PNI has a prevalence between 70 and 100%, surpassing any other solid tumor. PNI has been detected in the early stages of pancreatic cancer and has been associated with pain, increased tumor recurrence and diminished overall survival. Such an early, invasive and recurrent phenomenon is probably crucial for tumor growth and metastasis. PNI is a still not a uniformly characterized event; usually it is described only dichotomously ("present" or "absent"). Recently, a more detailed scoring system for PNI has been proposed, though not specific for pancreatic cancer. Previous studies have implicated several molecules and pathways in PNI, among which are secreted neurotrophins, chemokines and inflammatory cells. However, the mechanisms underlying PNI are poorly understood and several aspects are actively being investigated. In this review, we will discuss the main molecules and signaling pathways implicated in PNI and their roles in the PDAC.

Mesenchymal stem cell exosomes as a cell-free therapy for nerve injury-induced pain in rats

Nerve injury-induced neuropathic pain is difficult to treat. In this study, we used exosomes derived from human umbilical cord mesenchymal stem cell (UCMSC) as a cell-free therapy for nerve injury-induced pain in rats. Isolated UCMSC exosomes range in size from 30 to 160 nm and contain CD63, HSP60, and CD81 exosome markers. After L5/6 spinal nerve ligation surgery, single intrathecal injection of exosomes reversed nerve ligation-induced mechanical and thermal hypersensitivities of right hindpaw of rats at initial and well-developed pain stages. Moreover, continuous intrathecal infusion of exosomes achieved excellent preventive and reversal effects for nerve ligation-induced pain. In immunofluorescent study, lots of Exo-green-labelled exosomes could be found majorly in the ipsilateral L5 spinal dorsal horn, dorsal root ganglion, and peripheral axons, suggesting the homing ability of UCMSC exosomes. They also appeared in the central terminals or cell bodies of IB4, CGRP, and NF200 sensory neurons. In addition, exosome treatment suppressed nerve ligation-induced upregulation of c-Fos, CNPase, GFAP, and Iba1. All these data suggest that the analgesic effects of exosomes may involve their actions on neuron and glial cells. Exosomes also inhibited the level of TNF-α and IL-1β, while enhanced the level of IL-10, brain-derived neurotrophic factor, and glial cell line-derived neurotrophic factor in the ipsilateral L5/6 dorsal root ganglion of nerve-ligated rats, indicating anti-inflammatory and proneurotrophic abilities. Protein analysis revealed the content of vascular endothelial growth factor C, angiopoietin-2, and fibroblast growth factor-2 in the exosomes. In summary, intrathecal infusion of exosomes from UCMSCs may be considered as a novel therapeutic approach for nerve injury-induced pain.

Development of the Adverse Outcome Pathway (AOP): Chronic binding of antagonist to N-methyl-d-aspartate receptors (NMDARs) during brain development induces impairment of learning and memory abilities of children

The Adverse Outcome Pathways (AOPs) are designed to provide mechanistic understanding of complex biological systems and pathways of toxicity that result in adverse outcomes (AOs) relevant to regulatory endpoints. AOP concept captures in a structured way the causal relationships resulting from initial chemical interaction with biological target(s) (molecular initiating event) to an AO manifested in individual organisms and/or populations through a sequential series of key events (KEs), which are cellular, anatomical and/or functional changes in biological processes. An AOP provides the mechanistic detail required to support chemical safety assessment, the development of alternative methods and the implementation of an integrated testing strategy. An example of the AOP relevant to developmental neurotoxicity (DNT) is described here following the requirements of information defined by the OECD Users' Handbook Supplement to the Guidance Document for developing and assessing AOPs. In this AOP, the binding of an antagonist to glutamate receptor N-methyl-d-aspartate (NMDAR) receptor is defined as MIE. This MIE triggers a cascade of cellular KEs including reduction of intracellular calcium levels, reduction of brain derived neurotrophic factor release, neuronal cell death, decreased glutamate presynaptic release and aberrant dendritic morphology. At organ level, the above mentioned KEs lead to decreased synaptogenesis and decreased neuronal network formation and function causing learning and memory deficit at organism level, which is defined as the AO. There are in vitro, in vivo and epidemiological data that support the described KEs and their causative relationships rendering this AOP relevant to DNT evaluation in the context of regulatory purposes.

Development of the Adverse Outcome Pathway (AOP): Chronic binding of antagonist to N-methyl-d-aspartate receptors (NMDARs) during brain development induces impairment of learning and memory abilities of children

The Adverse Outcome Pathways (AOPs) are designed to provide mechanistic understanding of complex biological systems and pathways of toxicity that result in adverse outcomes (AOs) relevant to regulatory endpoints. AOP concept captures in a structured way the causal relationships resulting from initial chemical interaction with biological target(s) (molecular initiating event) to an AO manifested in individual organisms and/or populations through a sequential series of key events (KEs), which are cellular, anatomical and/or functional changes in biological processes. An AOP provides the mechanistic detail required to support chemical safety assessment, the development of alternative methods and the implementation of an integrated testing strategy. An example of the AOP relevant to developmental neurotoxicity (DNT) is described here following the requirements of information defined by the OECD Users' Handbook Supplement to the Guidance Document for developing and assessing AOPs. In this AOP, the binding of an antagonist to glutamate receptor N-methyl-d-aspartate (NMDAR) receptor is defined as MIE. This MIE triggers a cascade of cellular KEs including reduction of intracellular calcium levels, reduction of brain derived neurotrophic factor release, neuronal cell death, decreased glutamate presynaptic release and aberrant dendritic morphology. At organ level, the above mentioned KEs lead to decreased synaptogenesis and decreased neuronal network formation and function causing learning and memory deficit at organism level, which is defined as the AO. There are in vitro, in vivo and epidemiological data that support the described KEs and their causative relationships rendering this AOP relevant to DNT evaluation in the context of regulatory purposes.

Developmental origins of adult health and disease: The metabolic role of BDNF from early life to adulthood

Accumulating evidence suggests that the origins of adult disease may occur during fetal life. Thus, the concept of "developmental programming" has been introduced and supported by epidemiological and experimental data. This concept supports the idea that the nutritional and hormonal status during pregnancy could interfere in metabolism control. The mechanisms responsible for this "developmental programming" remain poorly documented. Current research indicates that neurotrophins and particularly brain-derived neurotrophic factor (BDNF) may play a crucial role in this process. Although mainly expressed in the nervous system, BDNF and its receptor, tropomyosin-related kinase B (TrkB), are immunolocalized in several regions of the human placenta and have important functions during pregnancy. BDNF serves widespread roles in regulating energy homeostasis in both fetuses and adults, by controlling patterns of fetal growth, adult feeding and physical activity, and by regulating glucose metabolism in peripheral tissues. Impaired BDNF signaling may be implicated in the etiopathogenesis of the metabolic syndrome. Novel BDNF-focused interventions are being developed for obesity, diabetes and neurological disorders. The aim of this article is to provide a brief comprehensive literary review regarding the potential implications of BDNF in "developmental programming", through regulation of metabolism and energy balance from early life to adulthood.

Perinatal hypoxia as a risk factor for psychopathology later in life: the role of dopamine and neurotrophins

Brain development is influenced by various prenatal, intrapartum, and postnatal events which may interact with genotype to affect the neural and psychophysiological systems related to emotions, specific cognitive functions (e.g., attention, memory), and language abilities and thereby heighten the risk for psychopathology later in life. Fetal hypoxia (intrapartum oxygen deprivation), hypoxia-related obstetric complications, and hypoxia during the early neonatal period are major environmental risk factors shown to be associated with an increased risk for later psychopathology. Experimental models of perinatal hypoxia/ischemia (PHI) showed that fetal hypoxia-a consequence common to many birth complications in humans-results in selective long-term disturbances of the dopaminergic systems that persist in adulthood. On the other hand, neurotrophic signaling is critical for pre- and postnatal brain development due to its impact on the process of neuronal development and its reaction to perinatal stress. The aim of this review is (a) to summarize epidemiological data confirming an association of PHI with an increased risk of a range of psychiatric disorders from childhood through adolescence to adulthood, (b) to present immunohistochemical findings on human autopsy material indicating vulnerability of the dopaminergic neurons of the human neonate to PHI that could predispose infant survivors of PHI to dopamine-related neurological and/or cognitive deficits in adulthood, and

TrkB receptor antagonism inhibits stab injury induced proliferative response in adult zebrafish (Danio rerio) brain

The Tropomyosin related kinase B (TrkB) receptor, is known to promote neuronal maturation, differentiation, maintenance and survival through its cognate ligands Brain derived neurotrophic factor (BDNF) and neurotrophin 4 (NT4). BDNF, NT4 and TrkB are highly conserved proteins among vertebrates. Although the role of TrkB during brain development is well established, its role in adult neurogenesis and brain regeneration awaits thorough investigation. In this study, we used the zebrafish stab wound injury model to determine whether the injury induced regeneration response in the telencephalon region is governed by TrkB or not. We induced stab wound injury in the mid-dorsal region of telencephalon of ANA-12 (selective TrkB antagonist) treated and non-treated zebrafish brain and examined the proliferation activity in selected brain regions using immunohistochemistry. We found that proliferation activity was significantly low in ANA-12 injected injured fishes as compared to vehicle control injured fishes. Other major findings of the study include the temporal pattern of proliferation activity after an injury and activation of adult neural stem cells (aNSCs) situated distantly apart from the injury site in the adult zebrafish brain.

Brain-Derived Neurotrophic Factor in Plasma of Women with Endometriosis

Purpose

Endometriosis is one of the most common benign gynecological diseases affecting women of reproductive age; it is characterized by the presence and growth of ectopic endometrial tissue outside the endometrial cavity. This complex disease is frequently associated with infertility and pelvic pain. Given the relationship and the apparent importance of the role that neurotrophins play in the reproductive system, and in particular brain-derived neurotrophic factor (BDNF) which is involved in both the central and peripheral pain pathways, we were interested in determining whether the presence of endometriosis is associated and correlated with plasma and follicular fluid variation of BDNF.

Methods

We determined BDNF level in plasma and in follicular fluid from infertile women with endometriosis and fertile women without the disease.

Results

BDNF plasma levels were significantly higher in endometriotic patients than in control women (p<0.001). After surgery this level decreased significantly (p<0.001), ranging within the values of control women in follicular phase. In follicular fluid, BDNF values were significantly lower in infertile women for endometriosis than in infertile women for male factors (p<0.001).

Conclusion

These data raise the possibility that neuroinflammatory reactions in endometriosis could have a neuroprotective effect and support the hypothesis that BDNF represents an important link in the networks of human homeostasis, thus providing an early marker for patients affected by endometriosis. Moreover, low BDNF levels in follicular fluid may refect an altered ovary production and may be a marker of poor oocyte quality and poor fertility in women suffering from endometriosis.

Prevalence of depression and anxiety in rheumatoid arthritis patients and their associations with serum vitamin D level

Vitamin D deficiency may be associated with depression in the general population. This study aimed to describe the prevalence of depression and anxiety in rheumatoid arthritis (RA) patients from Northwestern China and identify associations of Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) scores with serum vitamin D level in these patients. We recruited 161 RA patients inform the First Affiliated Hospital of Xi'an Jiaotong University during Nov. 2016 to Feb. 2017. All patients completed a survey including HAMD and HAMA scales. RA activity (DAS28) was scored by a rheumatologist, and serum 25-OH-D3 levels were measured by electrochemiluminescence immunoassay. The data were analyzed using the SPSS16.0 based on "possible and probable" cut points for HAMD and HAMA. About 62 and 60% of patients had some degrees of depression and anxiety, respectively. The mean of serum 25-OH-D3 levels in RA patients with depression was 15.24 ± 8.78 ng/mL, which was significantly lower than those without depression (24.68 ± 10.98 ng/mL, p = 0.009). Despite negative correlations between serum 25-OH-D3 level and the score of HAMD (r = - 0.520, p < 0.001) or HAMA (r = - 0.469, p < 0.001), there was a positive correlations between DAS28and the score of HAMD (r = 0.459, p = 0.001) or HAMA (r = 0.486, p < 0.001). The multivariate logistic regression showed that disease duration, serum 25-OH-D3 level, and treatment of tumor necrosis factor inhibitor were associated with depression/anxiety in RA patients. Our study shows a high prevalence of depression and anxiety in RA patients from Northwestern China. Both disease activity of RA and low serum 25-OH-D3 level are associated with the severity of depression and anxiety. It is imperative for clinicians to screen hypovitaminosis of vitamin D and depression/anxiety in RA patients.

Developmental neurotoxicity of the organophosphorus insecticide chlorpyrifos: from clinical findings to preclinical models and potential mechanisms

Organophosphorus (OP) insecticides are pest-control agents heavily used worldwide. Unfortunately, they are also well known for the toxic effects that they can trigger in humans. Clinical manifestations of an acute exposure of humans to OP insecticides include a well-defined cholinergic crisis that develops as a result of the irreversible inhibition of acetylcholinesterase (AChE), the enzyme that hydrolyzes the neurotransmitter acetylcholine (ACh). Prolonged exposures to levels of OP insecticides that are insufficient to trigger signs of acute intoxication, which are hereafter referred to as subacute exposures, have also been associated with neurological deficits. In particular, epidemiological studies have reported statistically significant correlations between prenatal subacute exposures to OP insecticides, including chlorpyrifos, and neurological deficits that range from cognitive impairments to tremors in childhood. The primary objectives of this article are: (i) to address the short- and long-term neurological issues that have been associated with acute and subacute exposures of humans to OP insecticides, especially early in life (ii) to discuss the translational relevance of animal models of developmental exposure to OP insecticides, and (iii) to review mechanisms that are likely to contribute to the developmental neurotoxicity of OP insecticides. Most of the discussion will be focused on chlorpyrifos, the top-selling OP insecticide in the United States and throughout the world. These points are critical for the identification and development of safe and effective interventions to counter and/or prevent the neurotoxic effects of these chemicals in the developing brain. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.

Roles of neurotrophins in skeletal tissue formation and healing

Neurotrophins and their receptors are key molecules that are known to be critical in regulating nervous system development and maintenance and have been recognized to be also involved in regulating tissue formation and healing in skeletal tissues. Studies have shown that neurotrophins and their receptors are widely expressed in skeletal tissues, implicated in chondrogenesis, osteoblastogenesis, and osteoclastogenesis, and are also involved in regulating tissue formation and healing events in skeletal tissue. Increased mRNA expression for neurotrophins NGF, BDNF, NT-3, and NT-4, and their Trk receptors has been observed in injured bone tissues, and NT-3 and its receptor, TrkC, have been identified to have the highest induction at the injury site in a drill-hole injury repair model in both bone and the growth plate. In addition, NT-3 has also recently been shown to be both an osteogenic and angiogenic factor, and this neurotrophin can also enhance expression of the key osteogenic factor, BMP-2, as well as the major angiogenic factor, VEGF, to promote bone formation, vascularization, and healing of the injury site. Further studies, however, are needed to investigate if different neurotrophins have differential roles in skeletal repair, and if NT-3 can be a potential target of intervention for promoting bone fracture healing.

Sigma-1 receptor in brain ischemia/reperfusion: Possible role in the NR2A-induced pathway to regulate brain-derived neurotrophic factor

Sigma-1 receptor (σ1r) activation could attenuate the learning and memory deficits in the AD model, ischemia model and others. In our previous study, the activation of σ1r increased the expression of brain-derived neurotrophic factor (BDNF), possibly through the NR2A-induced pathway, and σ1r agonists might function as neuroprotectant agents in vascular dementia. Here, we used σ1r knockout mice to confirm the role of σ1r. Furthermore, an antagonist of NR2A was first used to investigate whether the NR2A-induced pathway is the necessary link between σ1r and BDNF. The operation of brain ischemia/reperfusion was induced by bilateral common carotid artery occlusion for 20min in C57BL/6 and σ1r knockout mice as the ischemic group. A σ1r agonist, PRE084 (1mg/kg, i.p.), and NR2A antagonist, PEAQX (10mg/kg, i.p.), were administered once daily throughout the experiment. Behavioral tests were performed starting on day 8. On day 22 after brain ischemia/reperfusion, mice were sacrificed and brains were immediately collected and the injured and the hippocampus was isolated and stored at -80°C for western blot analysis. After ischemic operation, contrast with the σ1r knockout mice, PRE084 significantly ameliorated learning and memory impairments in the behavioral evaluation, and prevented the protein decline of BDNF, NR2A, CaMKIV and TORC1 expression in wild-type mice. However, the effects of PRE084 on CaMKIV-TORC1-CREB and BDNF, even for learning and memory impairment, were antagonized by the co-administration of PEAQX, an antagonist of NR2A. The activation of σ1r improves the impairment of learning and memory in the ischemia/reperfusion model, and the expression of BDNF, which may have been achieved through the NR2A-CaMKIV-TORC1 pathway.

Glucocorticoid receptor represses brain-derived neurotrophic factor expression in neuron-like cells

Brain-derived neurotrophic factor (BDNF) is involved in many functions such as neuronal growth, survival, synaptic plasticity and memorization. Altered expression levels are associated with many pathological situations such as depression, epilepsy, Alzheimer’s, Huntington’s and Parkinson’s diseases. Glucocorticoid receptor (GR) is also crucial for neuron functions, via binding of glucocorticoid hormones (GCs). GR actions largely overlap those of BDNF. It has been proposed that GR could be a regulator of BDNF expression, however the molecular mechanisms involved have not been clearly defined yet. Herein, we analyzed the effect of a GC agonist dexamethasone (DEX) on BDNF expression in mouse neuronal primary cultures and in the newly characterized, mouse hippocampal BZ cell line established by targeted oncogenesis. Mouse Bdnf gene exhibits a complex genomic structure with 8 untranslated exons (I to VIII) splicing onto one common and unique coding exon IX. We found that DEX significantly downregulated total BDNF mRNA expression by around 30%. Expression of the highly expressed exon IV and VI containing transcripts was also reduced by DEX. The GR antagonist RU486 abolished this effect, which is consistent with specific GR-mediated action. Transient transfection assays allowed us to define a short 275 bp region within exon IV promoter responsible for GR-mediated Bdnf repression. Chromatin immunoprecipitation experiments demonstrated GR recruitment onto this fragment, through unidentified transcription factor tethering. Altogether, GR downregulates Bdnf expression through direct binding to Bdnf regulatory sequences. These findings bring new insights into the crosstalk between GR and BDNF signaling pathways both playing a major role in physiology and pathology of the central nervous system.

Early neurotrophic pharmacotherapy rescues developmental delay and Alzheimer's-like memory deficits in the Ts65Dn mouse model of Down syndrome

Down syndrome (DS), caused by trisomy 21, is the most common genetic cause of intellectual disability and is associated with a greatly increased risk of early-onset Alzheimer’s disease (AD). The Ts65Dn mouse model of DS exhibits several key features of the disease including developmental delay and AD-like cognitive impairment. Accumulating evidence suggests that impairments in early brain development caused by trisomy 21 contribute significantly to memory deficits in adult life in DS. Prenatal genetic testing to diagnose DS in utero, provides the novel opportunity to initiate early pharmacological treatment to target this critical period of brain development. Here, we report that prenatal to early postnatal treatment with a ciliary neurotrophic factor (CNTF) small-molecule peptide mimetic, Peptide 021 (P021), rescued developmental delay in pups and AD-like hippocampus-dependent memory impairments in adult life in Ts65Dn mice. Furthermore, this treatment prevented pre-synaptic protein deficit, decreased glycogen synthase kinase-3beta (GSK3β) activity, and increased levels of synaptic plasticity markers including brain derived neurotrophic factor (BNDF) and phosphorylated CREB, both in young (3-week-old) and adult (~ 7-month-old) Ts65Dn mice. These findings provide novel evidence that providing neurotrophic support during early brain development can prevent developmental delay and AD-like memory impairments in a DS mouse model.

In vitro non-viral murine pro-neurotrophin 3 gene transfer into rat bone marrow stromal cells

Neurotrophin 3 (NT-3) is an important factor for promoting prenatal neural development, as well as regeneration, axogenesis and plasticity in postnatal life. Therapy with NT-3 was reported to improve the condition of patients suffering from degenerative diseases and traumatic injuries, however, the disadvantage of NT-3 protein delivery is its short half-life, thus our alternative approach is the use of NT-3 gene therapy. In this study, the bone marrow stromal cells (BMSCs) were isolated from adult rats, cultured for 4 passages and transfected with either pEGFP-N1 or a constructed vector containing murine proNT-3 (pSecTag2/HygroB-murine proNT-3) using Lipofectamine 2000 followed by Hygromycin B (200mg/kg). The transfection efficiency of the transiently transfected BMSCs was evaluated using the green fluorescence protein containing vector (pEGFP-N1). A quantitative evaluation of the NT-3 expression of mRNA using real time qRT-PCR shows that there was double fold increase in NT-3 gene expression compared with non-transfected BMSCs, also, the culture supernatant yielded double fold increase in NT-3 using ELISA technique, the data were supported by immunoblotting technique. This suggests that the use of this transfection technique can be useful for gene therapy in different neurological disorders with neurodegenerative or traumatic origins.

Mesenchymal Stromal Cells Promote Axonal Outgrowth Alone and Synergistically with Astrocytes via tPA

We reported that mesenchymal stromal cells (MSCs) enhance neurological recovery from experimental stroke and increase tissue plasminogen activator (tPA) expression in astrocytes. Here, we investigate mechanisms by which tPA mediates MSC enhanced axonal outgrowth. Primary murine neurons and astrocytes were isolated from wild-type (WT) and tPA-knockout (KO) cortices of embryos. Mouse MSCs (WT) were purchased from Cognate Inc. Neurons (WT or KO) were seeded in soma side of Xona microfluidic chambers, and astrocytes (WT or KO) and/or MSCs in axon side. The chambers were cultured as usual (normoxia) or subjected to oxygen deprivation. Primary neurons (seeded in plates) were co-cultured with astrocytes and/or MSCs (in inserts) for Western blot. In chambers, WT axons grew significantly longer than KO axons and exogenous tPA enhanced axonal outgrowth. MSCs increased WT axonal outgrowth alone and synergistically with WT astrocytes at both normoxia and oxygen deprivation conditions. The synergistic effect was inhibited by U0126, an ERK inhibitor, and receptor associated protein (RAP), a low density lipoprotein receptor related protein 1 (LRP1) ligand antagonist. However, MSCs exerted neither individual nor synergistic effects on KO axonal outgrowth. Western blot showed that MSCs promoted astrocytic tPA expression and increased neuronal tPA alone and synergistically with astrocytes. Also, MSCs activated neuronal ERK alone and synergistically with astrocytes, which was inhibited by RAP. We conclude: (1) MSCs promote axonal outgrowth via neuronal tPA and synergistically with astrocytic tPA; (2) neuronal tPA is critical to observe the synergistic effect of MSC and astrocytes on axonal outgrowth; and (3) tPA mediates MSC treatment-induced axonal outgrowth through the LRP1 receptor and ERK.

Vitamin D deficiency, behavioral atypicality, anxiety and depression in children with chromosome 22q11.2 deletion syndrome

Chromosome 22q11.2 deletion syndrome (22q11.2DS) is a complex developmental disorder with serious medical, cognitive and emotional symptoms across the lifespan. This genetic deletion also imparts a lifetime risk for developing schizophrenia that is 25-30 times that of the general population. The origin of this risk is multifactorial and may include dysregulation of the stress response and immunological systems in relation to brain development. Vitamin D is involved in brain development and neuroprotection, gene transcription, immunological regulation and influences neuronal signal transduction. Low levels of vitamin D are associated with schizophrenia, depression and anxiety in the general population. Yet, little is known about how vitamin D levels in children with 22q11.2DS could mediate risk of psychosis in adulthood. Blood plasma levels of vitamin D were measured in children aged 7-16 years with (n=11) and without (n=16) 22q11.2DS in relation to parent reports of children's anxiety and atypicality. Anxiety and atypicality in childhood are risk indicators for the development of schizophrenia in those with 22q11.2DS and the general population. Children with 22q11.2DS had lower vitamin D levels, as well as elevated anxiety and atypicality compared with typical peers. Higher levels of anxiety, depression and internalizing problems but not atypicality were associated with lower levels of vitamin D. Vitamin D insufficiency may relate to higher levels of anxiety and depression, in turn contributing to the elevated risk of psychosis in this population. Further study is required to determine casual linkages between anxiety, stress, mood and vitamin D in children with 22q11.2DS.

Neurotrophins in the Brain: Interaction With Alcohol Exposure During Development

Fetal alcohol spectrum disorders (FASDs) are a result of the teratogenic effects of alcohol on the developing fetus. Decades of research examining both individuals with FASDs and animal models of developmental alcohol exposure have revealed the devastating effects of alcohol on brain structure, function, behavior, and cognition. Neurotrophic factors have an important role in guiding normal brain development and cellular plasticity in the adult brain. This chapter reviews the current literature showing that alcohol exposure during the developmental period impacts neurotrophin production and proposes avenues through which alcohol exposure and neurotrophin action might interact. These areas of overlap include formation of long-term potentiation, oxidative stress processes, neuroinflammation, apoptosis and cell loss, hippocampal adult neurogenesis, dendritic morphology and spine density, vasculogenesis and angiogenesis, and behaviors related to spatial memory, anxiety, and depression. Finally, we discuss how neurotrophins have the potential to act in a compensatory manner as neuroprotective molecules that can combat the deleterious effects of in utero alcohol exposure.

Neurotrophin-3 Induces BMP-2 and VEGF Activities and Promotes the Bony Repair of Injured Growth Plate Cartilage and Bone in Rats

Injured growth plate is often repaired by bony tissue causing bone growth defects, for which the mechanisms remain unclear. Because neurotrophins have been implicated in bone fracture repair, here we investigated their potential roles in growth plate bony repair in rats. After a drill-hole injury was made in the tibial growth plate and bone, increased injury site mRNA expression was observed for neurotrophins NGF, BDNF, NT-3, and NT-4 and their Trk receptors. NT-3 and its receptor TrkC showed the highest induction. NT-3 was localized to repairing cells, whereas TrkC was observed in stromal cells, osteoblasts, and blood vessel cells at the injury site. Moreover, systemic NT-3 immunoneutralization reduced bone volume at injury sites and also reduced vascularization at the injured growth plate, whereas recombinant NT-3 treatment promoted bony repair with elevated levels of mRNA for osteogenic markers and bone morphogenetic protein (BMP-2) and increased vascularization and mRNA for vascular endothelial growth factor (VEGF) and endothelial cell marker CD31 at the injured growth plate. When examined in vitro, NT-3 promoted osteogenesis in rat bone marrow stromal cells, induced Erk1/2 and Akt phosphorylation, and enhanced expression of BMPs (particularly BMP-2) and VEGF in the mineralizing cells. It also induced CD31 and VEGF mRNA in rat primary endothelial cell culture. BMP activity appears critical for NT-3 osteogenic effect in vitro because it can be almost completely abrogated by co-addition of the BMP inhibitor noggin. Consistent with its angiogenic effect in vivo, NT-3 promoted angiogenesis in metatarsal bone explants, an effect abolished by co-treatment with anti-VEGF. This study suggests that NT-3 may be an osteogenic and angiogenic factor upstream of BMP-2 and VEGF in bony repair, and further studies are required to investigate whether NT-3 may be a potential target for preventing growth plate faulty bony repair or for promoting bone fracture healing. © 2016 American Society for Bone and Mineral Research.

Developing and applying the adverse outcome pathway concept for understanding and predicting neurotoxicity

The Adverse Outcome Pathway (AOP) concept has recently been proposed to support a paradigm shift in regulatory toxicology testing and risk assessment. This concept is similar to the Mode of Action (MOA), in that it describes a sequence of measurable key events triggered by a molecular initiating event in which a stressor interacts with a biological target. The resulting cascade of key events includes molecular, cellular, structural and functional changes in biological systems, resulting in a measurable adverse outcome. Thereby, an AOP ideally provides information relevant to chemical structure-activity relationships as a basis for predicting effects of structurally similar compounds. AOPs could potentially also form the basis for qualitative and quantitative predictive modeling of the human adverse outcome resulting from molecular initiating or other key events for which higher-throughput testing methods are available or can be developed. A variety of cellular and molecular processes are known to be critical for normal function of the central (CNS) and peripheral nervous systems (PNS). Because of the biological and functional complexity of the CNS and PNS, it has been challenging to establish causative links and quantitative relationships between key events that comprise the pathways leading from chemical exposure to an adverse outcome in the nervous system. Following introduction of the principles of MOA and AOPs, examples of potential or putative adverse outcome pathways specific for developmental or adult neurotoxicity are summarized and aspects of their assessment considered. Their possible application in developing mechanistically informed Integrated Approaches to Testing and Assessment (IATA) is also discussed.

Association Between Serum Levels of Vitamin D and the Risk of Post-Stroke Anxiety

Low levels of serum vitamin D are common in patients with mood disorders and stroke. It has been shown that low levels of serum vitamin D indicate a risk of depression in post-stroke subjects. Our aim was to determine the relationship between vitamin D and post-stroke anxiety (PSA).A consecutive series of 226 first acute ischemic stroke patients were recruited and followed up for 1 month. Serum levels of vitamin D were measured within 24 hours of admission. Patients with significant clinical symptoms of anxiety and a Hamilton anxiety scale score >7 were diagnosed as having PSA. In addition, 100 healthy subjects were recruited as controls and underwent measurements of serum vitamin D.A total of 60 patients (26.55%) showed anxiety at 1 month. Both PSA patients and non-PSA patients had lower serum levels of vitamin D than healthy subjects. A significant relationship was found between PSA and serum levels of vitamin D. Low serum levels of vitamin D (≤38.48 nmol/L) were independently associated with the development of PSA (OR: 2.49, 95% CI: 1.21-5.13, P = 0.01).Serum vitamin D status is related to the occurrence of anxiety in post-stroke patients and may be an independent risk factor of PSA after 1 month.

Altered microRNA expression profiles in a rat model of spina bifida

MicroRNAs (miRNAs) are dynamically regulated during neurodevelopment, yet few reports have examined their role in spina bifida. In this study, we used an established fetal rat model of spina bifida induced by intragastrically administering olive oil-containing all-trans retinoic acid to dams on day 10 of pregnancy. Dams that received intragastric administration of all-trans retinoic acid-free olive oil served as controls. The miRNA expression profile in the amniotic fluid of rats at 20 days of pregnancy was analyzed using an miRNA microarray assay. Compared with that in control fetuses, the expression of miRNA-9, miRNA-124a, and miRNA-138 was significantly decreased (> 2-fold), whereas the expression of miRNA-134 was significantly increased (> 4-fold) in the amniotic fluid of rats with fetuses modeling spina bifida. These results were validated using real-time quantitative reverse-transcription polymerase chain reaction. Hierarchical clustering analysis of the microarray data showed that these differentially expressed miRNAs could distinguish fetuses modeling spina bifida from control fetuses. Our bioinformatics analysis suggested that these differentially expressed miRNAs were associated with many cytological pathways, including a nervous system development signaling pathway. These findings indicate that further studies are warranted examining the role of miRNAs through their regulation of a variety of cell functional pathways in the pathogenesis of spina bifida. Such studies may provide novel targets for the early diagnosis and treatment of spina bifida.

Hyperbaric Oxygen Therapy Alleviates Carbon Monoxide Poisoning-Induced Delayed Memory Impairment by Preserving Brain-Derived Neurotrophic Factor-Dependent Hippocampal Neurogenesis

OBJECTIVE

To test the hypothesis that hyperbaric oxygen therapy ameliorates delayed cognitive impairment after acute carbon monoxide poisoning by promoting neurogenesis through upregulating the brain-derived neurotrophic factor in the hippocampus.

DESIGN

Laboratory animal experiments.

SETTING

University/Medical center research laboratory.

SUBJECTS

Adult, male Sprague-Dawley rats.

INTERVENTIONS

Rats were divided into five groups: (1) non-carbon monoxide-treated control, (2) acute carbon monoxide poisoning, (3) acute carbon monoxide poisoning followed by 7-day hyperbaric oxygen treatment, (4) carbon monoxide + hyperbaric oxygen with additional intracerebroventricular infusion of Fc fragment of tyrosine kinase receptor B protein (TrkB-Fc) chimera, and (5) acute carbon monoxide poisoning followed by intracerebroventricular infusion of brain-derived neurotrophic factor. Acute carbon monoxide poisoning was achieved by exposing the rats to carbon monoxide at 2,500 ppm for 40 minutes, followed by 3,000 ppm for 20 minutes. Hyperbaric oxygen therapy (at 2.5 atmospheres absolute with 100% oxygen for 60 min) was conducted during the first 7 days after carbon monoxide poisoning. Recombinant human TrkB-Fc chimera or brain-derived neurotrophic factor was infused into the lateral ventricle via the implanted osmotic minipump. For labeling of mitotic cells in the hippocampus, bromodeoxyuridine was injected into the peritoneal cavity. Distribution of bromodeoxyuridine and two additional adult neurogenesis markers, Ki-67 and doublecortin, in the hippocampus was evaluated by immunohistochemistry or immunofluorescence staining. Tissue level of brain-derived neurotrophic factor was assessed by enzyme-linked immunosorbent assay. Cognitive behavior was evaluated by the use of eight-arm radial maze.

MEASUREMENTS AND MAIN RESULTS

Acute carbon monoxide poisoning significantly suppressed adult hippocampal neurogenesis evident by the reduction in number of bromodeoxyuridine-positive, Ki-67⁺, and doublecortin⁺ cells in the subgranular zone of the dentate gyrus. This suppression of adult neurogenesis by the carbon monoxide poisoning was appreciably alleviated by early treatment of hyperbaric oxygen. The hyperbaric oxygen treatment also promoted a sustained increase in hippocampal brain-derived neurotrophic factor level. Blockade of hippocampal brain-derived neurotrophic factor signaling with intracerebroventricular infusion of recombinant human TrkB-Fc chimera significantly blunted the protection by the hyperbaric oxygen on hippocampal neurogenesis; whereas intracerebroventricular infusion of brain-derived neurotrophic factor mimicked the action of hyperbaric oxygen and preserved hippocampal neurogenesis after acute carbon monoxide poisoning. Furthermore, acute carbon monoxide poisoning resulted in a delayed impairment of cognitive function. The hyperbaric oxygen treatment notably restored the cognitive impairment in a brain-derived neurotrophic factor-dependent manner.

CONCLUSIONS

The early hyperbaric oxygen treatment may alleviate delayed memory impairment after acute carbon monoxide poisoning by preserving adult neurogenesis via an increase in hippocampal brain-derived neurotrophic factor content.

Maternal Exercise during Pregnancy Increases BDNF Levels and Cell Numbers in the Hippocampal Formation but Not in the Cerebral Cortex of Adult Rat Offspring

Clinical evidence has shown that physical exercise during pregnancy may alter brain development and improve cognitive function of offspring. However, the mechanisms through which maternal exercise might promote such effects are not well understood. The present study examined levels of brain-derived neurotrophic factor (BDNF) and absolute cell numbers in the hippocampal formation and cerebral cortex of rat pups born from mothers exercised during pregnancy. Additionally, we evaluated the cognitive abilities of adult offspring in different behavioral paradigms (exploratory activity and habituation in open field tests, spatial memory in a water maze test, and aversive memory in a step-down inhibitory avoidance task). Results showed that maternal exercise during pregnancy increased BDNF levels and absolute numbers of neuronal and non-neuronal cells in the hippocampal formation of offspring. No differences in BDNF levels or cell numbers were detected in the cerebral cortex. It was also observed that offspring from exercised mothers exhibited better cognitive performance in nonassociative (habituation) and associative (spatial learning) mnemonic tasks than did offspring from sedentary mothers. Our findings indicate that maternal exercise during pregnancy enhances offspring cognitive function (habituation behavior and spatial learning) and increases BDNF levels and cell numbers in the hippocampal formation of offspring.