Neural stem cell niche heterogeneity.

In mammals, new neurons can be generated from neural stem cells in specific regions of the adult brain. Neural stem cells are characterized by their abilities to differentiate into all neural lineages and to self-renew. The specific microenvironments regulating neural stem cells, commonly referred to as neurogenic niches, comprise multiple cell populations whose precise contributions are under active current exploration. Understanding the cross-talk between neural stem cells and their niche components is essential for the development of therapies against neurological disorders in which neural stem cells function is altered. In this review, we describe and discuss recent studies that identified novel components in the neural stem cell niche. These discoveries bring new concepts to the field. Here, we evaluate these recent advances that change our understanding of the neural stem cell niche heterogeneity and its influence on neural stem cell function.

Nonlinear and vibrational microscopy for label-free characterization of amyloid-ß plaques in Alzheimer's disease model.

Given the long subclinical stage of Alzheimer's disease (AD), the study of biomarkers is relevant both for early diagnosis and the fundamental understanding of the pathophysiology of AD. Biomarkers provided by Amyloid-ß (Aß) plaques have led to an increasing interest in characterizing this hallmark of AD due to its promising potential. In this work, we characterize Aß plaques by label-free multimodal imaging: we combine two-photon excitation autofluorescence (TPEA), second harmonic generation (SHG), spontaneous Raman scattering (SpRS), coherent anti-Stokes Raman scattering (CARS), and stimulated Raman scattering (SRS) to describe and compare high-resolution images of Aß plaques in brain tissues of an AD mouse model. Comparing single-laser techniques images, we discuss the origin of the SHG, which can be used to locate the plaque core reliably. We study both the core and the halo with vibrational microscopy and compare SpRS and SRS microscopies for different frequencies. We also combine SpRS spectroscopy with SRS microscopy and present two core biomarkers unexplored with SRS microscopy: phenylalanine and amide B. We provide high-resolution SRS images with the spatial distribution of these biomarkers in the plaque and compared them with images of the amide I distribution. The obtained spatial correlation corroborates the feasibility of these biomarkers in the study of Aß plaques. Furthermore, since amide B enables rapid imaging, we discuss its potential as a novel fingerprint for diagnostic applications.

Micro-Raman spectroscopy of lipid halo and dense-core amyloid plaques: aging process characterization in the Alzheimer's disease APPswePS1ΔE9 mouse model.

The deposition of amyloid plaques is considered one of the main microscopic features of Alzheimer's disease (AD). Since plaque formation can precede extensive neurodegeneration and it is the main clinical manifestation of AD, it constitutes a relevant target for new treatment and diagnostic approaches. Micro-Raman spectroscopy, a label-free technique, is an accurate method for amyloid plaque identification and characterization. Here, we present a high spatial resolution micro-Raman hyperspectral study in transgenic APPswePS1ΔE9 mouse brains, showing details of AD tissue biochemical and histological changes without staining. First we used stimulated micro-Raman scattering to identify the lipid-rich halo surrounding the amyloid plaque, and then proceeded with spontaneous (conventional) micro-Raman spectral mapping, which shows a cholesterol and sphingomyelin lipid-rich halo structure around dense-core amyloid plaques. The detailed images of this lipid halo relate morphologically well with dystrophic neurites surrounding plaques. Principal Component Analysis (PCA) of the micro-Raman hyperspectral data indicates the feasibility of the optical biomarkers of AD progression with the potential for discriminating transgenic groups of young adult mice (6-month-old) from older ones (12-month-old). Frequency-specific PCA suggests that plaque-related neurodegeneration is the predominant change captured by Raman spectroscopy, and the main differences are highlighted by vibrational modes associated with cholesterol located majorly in the lipid halo.

Pericytes Act as Key Players in Spinal Cord Injury.

Spinal cord injury results in locomotor impairment attributable to the formation of an inhibitory fibrous scar, which prevents axonal regeneration after trauma. The scarcity of knowledge about the molecular and cellular mechanisms involved in scar formation after spinal cord lesion impede the design of effective therapies. Recent studies, by using state-of-the-art technologies, including genetic tracking and blockage of pericytes in combination with optogenetics, reveal that pericyte blockage facilitates axonal regeneration and neuronal integration into the local neural circuitry. Strikingly, a pericyte subset is essential during scarring after spinal cord injury, and its arrest results in motor performance improvement. The arising knowledge from current research will contribute to novel approaches to develop therapies for spinal cord injury. We review novel advances in our understanding of pericyte biology in the spinal cord.

A fingerprint of amyloid plaques in a bitransgenic animal model of Alzheimer's disease obtained by statistical unmixing analysis of hyperspectral Raman data.

The global prevalence of Alzheimer's disease (AD) points to endemic levels, especially considering the increase of average life expectancy worldwide. AD diagnosis based on early biomarkers and better knowledge of related pathophysiology are both crucial in the search for medical interventions that are able to modify AD progression. In this study we used unsupervised spectral unmixing statistical techniques to identify the vibrational spectral signature of amyloid ß aggregation in neural tissues, as early biomarkers of AD in an animal model. We analyzed spectral images composed of a total of 55 051 Raman spectra obtained from the frontal cortex and hippocampus of five bitransgenic APPswePS1ΔE9 mice, and colocalized amyloid ß plaques by other fluorescence techniques. The Raman signatures provided a multifrequency fingerprint consistent with the results of synthesized amyloid ß fibrils. The fingerprint obtained from unmixed analysis in neural tissues is shown to provide a detailed image of amyloid plaques in the brain, with the potential to be used as biomarkers for non-invasive early diagnosis and pathophysiology studies in AD on the retina.

Evaluation of NCS-1, DARPP-32, and neurotrophins in hippocampus and prefrontal cortex in rats submitted to sepsis.

Sepsis is defined as the host's reaction to infection and it is characterized by a systemic inflammatory response with important clinical implications. Central nervous system dysfunction secondary to sepsis is associated with local generation of pro- and anti-inflammatory cytokines, impaired cerebral microcirculation, disturbance of neurotransmitters, apoptosis, and cognitive impairment. It is known that during the process of learning and memory formation several pathways are involved such as dopaminergic and cholinergic systems. Thus, the objective of this study is to evaluate the neuronal calcium sensor (NCS-1) and dopamine-cAMP regulated phosphoprotein of 32,000 kDa (DARPP-32) expression as well as brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels in prefrontal cortex and hippocampus of rats 12, 24, and 48 h after sepsis induction. To this aim, we used sham-operated Wistar rats or submitted to the cecal ligation and perforation procedure. After 12 and 24 h, there was an increase of NGF levels in hippocampus; and up to 48 h, a decrease of NCS-1 expression in prefrontal cortex, a decrease of BDNF levels in hippocampus and an increase of NGF levels in hippocampus. In conclusion, we believe that the low expression of NCS-1 in prefrontal cortex and low levels of BDNF in hippocampus may be associated with the pathophysiology of cognitive impairment during sepsis and a putative role of the dopaminergic system.

Examining differences in brain metabolism associated with childhood maltreatment and suicidal attempt in euthymic patients with bipolar disorder: A PET and Machine Learning Study.

OBJECTIVE: Childhood maltreatment (CM) is a significant risk factor for the development and severity of bipolar disorder (BD) with increased risk of suicide attempts (SA). This study evaluated whether a machine learning algorithm could be trained to predict if a patient with BD has a history of CM or previous SA based on brain metabolism measured by positron emission tomography. METHODS: Thirty-six euthymic patients diagnosed with BD type I, with and without a history of CM were assessed using the Childhood Trauma Questionnaire. Suicide attempts were assessed through the Mini International Neuropsychiatric Interview (MINI-Plus) and a semi-structured interview. Resting-state positron emission tomography with 18F-fluorodeoxyglucose was conducted, electing only grey matter voxels through the Statistical Parametric Mapping toolbox. Imaging analysis was performed using a supervised machine learning approach following Gaussian Process Classification. RESULTS: Patients were divided into 18 participants with a history of CM and 18 participants without it, along with 18 individuals with previous SA and 18 individuals without such history. The predictions for CM and SA were not significant (accuracy = 41.67%; p = 0.879). CONCLUSION: Further investigation is needed to improve the accuracy of machine learning, as its predictive qualities could potentially be highly useful in determining histories and possible outcomes of high-risk psychiatric patients.

Counterfactual inference with latent variable and its application in mental health care.

This paper deals with the problem of modeling counterfactual reasoning in scenarios where, apart from the observed endogenous variables, we have a latent variable that affects the outcomes and, consequently, the results of counterfactuals queries. This is a common setup in healthcare problems, including mental health. We propose a new framework where the aforementioned problem is modeled as a multivariate regression and the counterfactual model accounts for both observed and a latent variable, where the latter represents what we call the patient individuality factor ( φ ). In mental health, focusing on individuals is paramount, as past experiences can change how people see or deal with situations, but individuality cannot be directly measured. To the best of our knowledge, this is the first counterfactual approach that considers both observational and latent variables to provide deterministic answers to counterfactual queries, such as: what if I change the social support of a patient, to what extent can I change his/her anxiety? The framework combines concepts from deep representation learning and causal inference to infer the value of φ and capture both non-linear and multiplicative effects of causal variables. Experiments are performed with both synthetic and real-world datasets, where we predict how changes in people's actions may lead to different outcomes in terms of symptoms of mental illness and quality of life. Results show the model learns the individually factor with errors lower than 0.05 and answers counterfactual queries that are supported by the medical literature. The model has the potential to recommend small changes in people's lives that may completely change their relationship with mental illness.

Downregulation of the cAMP/PKA pathway in PC12 cells overexpressing NCS-1.

It is well known that dopamine imbalances are associated with many psychiatric disorders and that the dopaminergic receptor D2 is the main target of antipsychotics. Recently it was shown that levels of two proteins implicated in dopaminergic signaling, Neuronal calcium sensor-1 (NCS-1) and DARPP-32, are altered in the prefrontal cortex (PFC) of both schizophrenic and bipolar disorder patients. NCS-1, which inhibits D2 internalization, is upregulated in the PFC of both patients. DARPP-32, which is a downstream effector of dopamine signaling, integrates the pathways of several neurotransmitters and is downregulated in the PFC of both patients. Here, we used PC12 cells stably overexpressing NCS-1 (PC12-NCS-1 cells) to address the function of this protein in DARPP-32 signaling pathway in vitro. PC12-NCS-1 cells displayed downregulation of the cAMP/PKA pathway, with decreased levels of cAMP and phosphorylation of CREB at Ser133. We also observed decreased levels of total and phosphorylated DARPP-32 at Thr34. However, these cells did not show alterations in the levels of D2 and phosphorylation of DARPP-32 at Thr75. These results indicate that NCS-1 modulates PKA/cAMP signaling pathway. Identification of the cellular mechanisms linking NCS-1 and DARPP-32 may help in the understanding the signaling machinery with potential to be turned into targets for the treatment of schizophrenia and other debilitating psychiatric disorders.

Lack of association of NALCN genetic variants with schizophrenia.

NALCN (sodium leak channel, non-selective) is located on chromosome 13q (suggested linkage region for schizophrenia). We analyzed 21 polymorphisms in 464 schizophrenia subjects, 220 controls subjects and 119 small nuclear families. We observed nominal association with rs9518320 and rs9518331, suggesting that NALCN is not related to schizophrenia risk.

Neurochemical abnormalities in the hippocampus of male rats displaying audiogenic seizures, a genetic model of epilepsy.

BACKGROUND: Epilepsy is a disorder characterized by recurrent seizures that affects 1% of the population. However, the neurochemical alterations observed in epilepsy are not fully understood. There are different animal models of epilepsy, such as genetic or drug induced. In the present study, we utilize Wistar Audiogenic Rats (WAR), a murine strain that develops seizures in response to high intensity audio stimulation, in order to investigate abnormalities in glutamatergic and GABAergic systems. METHODS: Synaptosomes and glial plasmalemmal vesicles were prepared from hippocampus and cortex, respectively. Glutamate and GABA release and uptake were assayed by monitoring the fluorescence and using L-[3H]-radiolabeled compounds. Glutamate and calcium concentration in the synaptosomes were also measured. The expression of neuronal calcium sensor 1 (NCS-1) was determined by western blot. RESULTS: Glutamate and GABA release evoked by KCl was decreased in WAR compared to control Wistar rats. Calcium independent release was not considerably different in both groups. The total amount of glutamate of synaptosomes, as well as glutamate uptake by synaptosomes and GPV were also decreased in WAR in comparison with the controls. In addition, [Ca2+]i of hippocampal synaptosomes, as well as NCS-1 expression in the hippocampus, were increased in WAR in comparison with controls. CONCLUSION: In conclusion, our results suggest that WAR have important alterations in the glutamatergic and GABAergic pathways, as well as an increased expression of NCS-1 in the hippocampus and inferior colliculus. These alterations may be linked to the spreading of hyperexcitability and recruitment of various brain regions.

Lack of effects of typical and atypical antipsychotics in DARPP-32 and NCS-1 levels in PC12 cells overexpressing NCS-1.

BACKGROUND: Schizophrenia is the major psychiatry disorder, which the exact cause remains unknown. However, it is well known that dopamine-mediated neurotransmission imbalance is associated with this pathology and the main target of antipsychotics is the dopamine receptor D2. Recently, it was described alteration in levels of two dopamine signaling related proteins in schizophrenic prefrontal cortex (PFC): Neuronal Calcium Sensor-1 (NCS-1) and DARPP-32. NCS-1, which is upregulated in PFC of schizophrenics, inhibits D2 internalization. DARPP-32, which is decreased in PFC of schizophrenics, is a key downstream effector in transducing dopamine signaling. We previously demonstrated that antipsychotics do not change levels of both proteins in rat's brain. However, since NCS-1 and DARPP-32 levels are not altered in wild type rats, we treated wild type PC12 cells (PC12 WT) and PC12 cells stably overexpressing NCS-1 (PC12 Clone) with antipsychotics to investigate if NCS-1 upregulation modulates DARPP-32 expression in response to antipsychotics treatment. RESULTS: We chronically treated both PC12 WT and PC12 Clone cells with typical (Haloperidol) or atypical (Clozapine and Risperidone) antipsychotics for 14 days. Using western blot technique we observed that there is no change in NCS-1 and DARPP-32 protein levels in both PC12 WT and PC12 Clone cells after typical and atypical antipsychotic treatments. CONCLUSIONS: Because we observed no alteration in NCS-1 and DARPP-32 levels in both PC12 WT and Clone cells treated with typical or atypical antipsychotics, we suggest that the alteration in levels of both proteins in schizophrenic's PFC is related to psychopathology but not with antipsychotic treatment.

Transcranial Direct Current Stimulation: No Effect on Aerobic Performance, Heart Rate, or Rating of Perceived Exertion in a Progressive Taekwondo-Specific Test.

PURPOSE: To investigate the effects of anodal transcranial direct current stimulation (a-tDCS) on the aerobic performance, heart rate (HR), and rating of perceived exertion (RPE) of highly trained taekwondo athletes. METHODS: Twelve (8 men and 4 women) international/national-level athletes received a-tDCS or sham treatment over the M1 location in a randomized, single-blind crossover design. The stimulation was delivered at 1.5 mA for 15 min using an extracephalic bihemispheric montage. Athletes performed the progressive-specific taekwondo test 10 min after stimulation. HR was monitored continuously during the test, and RPE was registered at the end of each stage and at test cessation. RESULTS: There were no significant differences between sham and a-tDCS in time to exhaustion (14.6 and 14.9, respectively, P = .53, effect size = 0.15) and peak kicking frequency (52 and 53.6, respectively, P = .53, effect size = 0.15) or in HR (P > .05) and RPE responses (P > .05). CONCLUSIONS: Extracephalic bihemispheric a-tDCS over M1 did not influence the aerobic performance of taekwondo athletes or their psychophysiological responses, so athletes and staff should be cautious when using it in a direct-to-consumer manner.

Phoneutria spider toxins block ischemia-induced glutamate release, neuronal death, and loss of neurotransmission in hippocampus.

The aim of this study was to investigate the effect of spider toxins on brain injury induced by oxygen deprivation and low glucose (ODLG) insult on slices of rat hippocampus. After ODLG insult cell viabilility in hippocampal slices was assessed by confocal microscopy and epifluorescence using the live/dead kit containing calcein-AM and ethidium homodimer and CA1 population spike amplitude recording during stimulation of Schaffer collateral fibers. Spider toxins Tx3-3 or Tx3-4 and conus toxins, omega-conotoxin GVIA or omega-conotoxin MVIIC are calcium channel blockers and protected against neuronal damage in slices subjected to ODLG insult. Confocal imaging of CA1 region of rat hippocampal slices subject to ischemic insult treated with Tx3-3, Tx3-4, omega-conotoxin GVIA or omega-conotoxin MVIIC showed a decrease in cell death that amounted to 68 +/- 4.2%, 77 +/- 3.8%, 32 +/- 2.3%, and 46 +/- 2.9%, respectively. This neuroprotective effect of Tx3-4 was corroborated by eletrophysiological recordings of population spikes amplitudes in CA1. The neuroprotection promoted on hippocampal slices by Tx3-3 or Tx3-4 was also observed when the toxins were applied 10, 20, 30, 60, 90, or 120 min after induction of the ODLG injury. During the ischemic insult, glutamate release from slices was increased by 71% (from 7.0 +/- 0.3 nM/mg of protein control slices not subjected to ischemia to 12 +/- 0.4 nM/mg of protein in slices exposed to ischemia). Tx3-3, Tx3-4, omega-conotoxin GVIA or omega-conotoxin MVIIC inhibited the ischemia-induced increase on glutamate release by 54, 72, 60, and 70%, respectively. Thus Tx3-3 and Tx3-4 provided robust ischemic neuroprotection showing potential as a novel class of agent that exerts neuroprotection in an in vitro model of brain ischemia.

Cerebral DARPP-32 expression after methylphenidate administration in young and adult rats.

Dopamine may alter the phosphorylation state of DARPP-32 that plays a central role in the dopaminergic neurons biology. Studies have shown that DARPP-32/protein phosphatase 1 cascade is a major target for psychostimulants drugs. Methylphenidate is a psychostimulant that acts blocking the dopamine transporter has been used as an effective treatment for Attention Deficit Hyperactivity Disorder. We investigated if methylphenidate could alter DARPP-32 expression in five brain regions (striatum, hippocampus, prefrontal cortex, cortex and cerebellum) in young and adult rats. Our results showed that methylphenidate treatment is able to alter DARPP-32 expression in rat brain. Acute methylphenidate treatment has reduced hippocampal DARPP-32 protein levels in old rats, while chronic methylphenidate treatment has decreased them in old rat hippocampus and young rat cerebellum. It was found an increased cortical expression after chronic methylphenidate administration in old rats. Our results provide the first experimental demonstration that methylphenidate induces changes in total DARPP-32 expression that are posology- and age-related in some rat brain areas, although further studies are needed to shed more light on the mechanisms behind these findings.

Lack of association of GPX1 and MnSOD genes with symptom severity and response to clozapine treatment in schizophrenia subjects.

Abnormal activities of critical antioxidant enzymes and other indices of lipid peroxidation in plasma and red blood cells were detected in patients with schizophrenia. Other results have shown that oxidative stress may be modulated by clozapine. Based on that and some studies already found different clinical relations between reactive oxygen species and negative and positive symptoms, we evaluated association between clinical response and the polymorphism in the human glutathione peroxidase (GPX1) (Pro200Leu, rs1050450) and manganese SOD (MNSOD) (Ala16Val, rs4880) gene in 216 clozapine-treated patients with schizophrenia. No association was found with these two functional polymorphisms and clozapine response and symptom change after 6 months. No correlations were found between positive/negative symptoms score and both polymorphisms. Our results present that GPX1 (Pro200Leu) and MNSOD (Ala16Val) polymorphisms seem do not play a central role in the clozapine response, although studies in larger and independent samples are necessary to confirm our findings.

Parent SNAP-IV rating of attention-deficit/hyperactivity disorder: accuracy in a clinical sample of ADHD, validity, and reliability in a Brazilian sample.

OBJECTIVE: To investigate the psychometric properties of the short or multimodal treatment study version of the Swanson, Nolan, and Pelham, Version IV (SNAP-IV) scale, which measures attention-deficit/hyperactivity disorder and oppositional defiant disorder symptoms. METHODS: Participants were 765 parents of children from 4 to 16 years old (641 non-attention-deficit/hyperactivity disorder and 124 attention-deficit/hyperactivity disorder children) from Belo Horizonte, Brazil, who reported sociodemographic characteristics and answered the SNAP-IV. Parents of the clinical sample also underwent the K-SADS-PL interview. RESULTS: Age was significantly associated with SNAP-IV hyperactivity-impulsivity problems (r=-0.14), but not with inattention or oppositional defiant disorder. Sex was a significant influence on attention-deficit/hyperactivity disorder and oppositional defiant disorder severity (all p<0.001), with boys showing higher scores in the full sample, but not within the attention-deficit/hyperactivity disorder group. Exploratory and confirmatory factor analysis supports a three-factor structure of the SNAP-IV scale. Moderate-to-strong correlations were found between SNAP-IV and K-SADS-PL measures. All SNAP-IV scales showed very high internal consistency coefficients (all above 0.91). SNAP-IV inattention scores were the most predictive of attention-deficit/hyperactivity disorder diagnosis (AUC: 0.877 for the averaging rating method and the raw sum method, and 0.874 for the symptom presence/absence method). CONCLUSION: The parent SNAP-IV showed good psychometric properties in a Brazilian school and clinical sample.

Pericyte Plasticity in the Brain.

Cerebral pericytes are perivascular cells that stabilize blood vessels. Little is known about the plasticity of pericytes in the adult brain in vivo. Recently, using state-of-the-art technologies, including two-photon microscopy in combination with sophisticated Cre/loxP in vivo tracing techniques, a novel role of pericytes was revealed in vascular remodeling in the adult brain. Strikingly, after pericyte ablation, neighboring pericytes expand their processes and prevent vascular dilatation. This new knowledge provides insights into pericyte plasticity in the adult brain.

Association study of GSK3 gene polymorphisms with schizophrenia and clozapine response.

RATIONALE: A number of human and animal studies implicate GSK3 in the pathophysiology and genetics of schizophrenia. In general, the data suggest that phosphorylation levels of GSK3beta are reduced in schizophrenia, resulting in increased GSK3beta activity. Since GSK3beta regulation is altered in schizophrenia, polymorphic variation in this gene may affect susceptibility to schizophrenia or treatment response. OBJECTIVE: To analyze GSK3beta genetic variants for association with schizophrenia and clozapine response. MATERIALS AND METHODS: We examined GSK3beta markers in 185 matched case-control subjects, 85 small nuclear families, and 150 schizophrenia patients treated with clozapine for 6 months. RESULTS: Three markers (rs7624540, rs4072520, and rs6779828) showed genotypic association with schizophrenia in the case-control sample. We did not observe any family and clozapine response association with a specific allele, genotype, or haplotype. CONCLUSIONS: Our results suggest that GSK3beta polymorphisms might be involved in schizophrenia risk but do not appear to play a significant role in clozapine response.