Glutamate And Γ-aminobutyric Acid Research Articles

Neuroactivity of detonation nanodiamonds: dose-dependent changes in transporter-mediated uptake and ambient level of excitatory/inhibitory neurotransmitters in brain nerve terminals.

BackgroundNanodiamonds are one of the most perspective nano-sized particles with superb physical and chemical properties, which are mainly composed of carbon sp3 structures in the core with sp2 and disorder/defect carbons on the surface. The research team recently demonstrated neuromodulatory properties of carbon nanodots with other than nanodiamonds hybridization types, i.e., sp2 hybridized graphene islands and diamond-like sp3 hybridized elements.ResultsIn this study, neuroactive properties of uncoated nanodiamonds produced by detonation synthesis were assessed basing on their effects on transporter-mediated uptake and the ambient level of excitatory and inhibitory neurotransmitters, glutamate and γ-aminobutyric acid (GABA), in isolated rat brain nerve terminals. It was shown that nanodiamonds in a dose-dependent manner attenuated the initial velocity of Na+-dependent transporter-mediated uptake and accumulation of l-[14C]glutamate and [3H]GABA by nerve terminals and increased the ambient level of these neurotransmitters. Also, nanodiamonds caused a weak reduction in acidification of synaptic vesicles and depolarization of the plasma membrane of nerve terminals.ConclusionsTherefore, despite different types of hybridization in nanodiamonds and carbon dots, they exhibit very similar effects on glutamate and GABA transport in nerve terminals and this common feature of both nanoparticles is presumably associated with their nanoscale size. Observed neuroactive properties of pure nanodiamonds can be used in neurotheranostics for simultaneous labeling/visualization of nerve terminals and modulation of key processes of glutamate- and GABAergic neurotransmission. In comparison with carbon dots, wider medical application involving hypo/hyperthermia, external magnetic fields, and radiolabel techniques can be perspective for nanodiamonds.

Shifts in excitatory/inhibitory balance by juvenile stress: A role for neuron–astrocyte interaction in the dentate gyrus

Childhood trauma is a well-described risk factor for the development of stress-related psychopathology such as posttraumatic stress disorder or depression later in life. Childhood adversity can be modeled in rodents by juvenile stress (JS) protocols, resulting in impaired coping with stressful challenges in adulthood. In the current study, we investigated the long-lasting impact of JS on the expression of molecular factors for glutamate and γ-aminobutyric acid (GABA) uptake and turnover in sublayers of the dentate gyrus (DG) using laser microdissection and quantitative real-time polymerase chain reaction. We observed reduced mRNA expression levels after JS for factors mediating astrocytic glutamate and GABA uptake and degradation. These alterations were prominently observed in the dorsal but not ventral DG granule cell layer, indicating a lasting change in astrocytic GABA and glutamate metabolism that may affect dorsal DG network activity. Indeed, we observed increased inhibition and a lack of facilitation in response to paired-pulse stimulation at short interstimulus intervals in the dorsal DG after JS, while no alterations were evident in basal synaptic transmission or forms of long-term plasticity. The shift in paired-pulse response was mimicked by pharmacologically blocking the astrocytic GABA transporter GAT-3 in naïve animals. Accordingly, reduced expression levels of GAT-3 were confirmed at the protein level in the dorsal granule cell layer of rats stressed in juvenility. Together, these data demonstrate a lasting shift in the excitatory/inhibitory balance of dorsal DG network activity by JS that appears to be mediated by decreased GABA uptake into astrocytes.

Frontal Glutamate and γ-Aminobutyric Acid Levels and Their Associations With Mismatch Negativity and Digit Sequencing Task Performance in Schizophrenia.

Auditory mismatch negativity (MMN) is a biomarker for schizophrenia thought to reflect glutamatergic N-methyl-d-aspartate receptor function and excitatory-inhibitory neurotransmission balance. However, the association of glutamate level with MMN has not been directly examined in patients with schizophrenia, to our knowledge. To investigate the contributions of glutamate and γ-aminobutyric acid (GABA) to MMN and digit sequencing task (DST) performance, an assessment of verbal working memory, in schizophrenia. Fifty-three control participants from the community and 45 persons with schizophrenia from outpatient clinics completed an electroencephalographic session for MMN, magnetic resonance spectroscopy for glutamate and GABA, and a DST. The study dates were July 2011 to May 2014, and the dates of our analysis were May 2014 to August 2015. Glutamate, GABA, the ratio of glutamine to glutamate, MMN amplitude, and DST. Structural equation modeling was used to test the effects of neurochemistry and MMN amplitude on DST performance. The 45 persons with schizophrenia were a mean (SD) of 37.7 (12.8) years and the control participants were 37.1 (13.1) years. The schizophrenia group had a mean (SD) of 14.7 (12.1) years of illness. Mismatch negativity amplitude (F = 4.39, P = .04) and glutamate (F = 9.69, P = .002) were reduced in the schizophrenia group. Smaller MMN amplitude was significantly associated with lower GABA level (P = .008), lower glutamate level (P = .05), and higher ratio of glutamine to glutamate (P = .003). Reduced MMN amplitude was linked to poor verbal working memory in schizophrenia (P = .002). Modeling revealed that a proxy of glutamatergic function, indexed by the ratio of glutamine to glutamate, influenced a path from the ratio of glutamine to glutamate to MMN to verbal working memory (P = .38 [root-mean-square error of approximation, P < .001] by χ2 test), supporting the contention that MMN serves as an intermediate biomarker linking glutamatergic function to DST performance in schizophrenia. The role of glutamate and GABA in MMN and verbal working memory deficits in schizophrenia has been frequently debated. These data provide in vivo evidence that support glutamatergic and GABAergic regulation of MMN and verbal working memory function in schizophrenia.

Euglycemia Restoration by Central Leptin in Type 1 Diabetes Requires STAT3 Signaling but Not Fast-Acting Neurotransmitter Release.

Central leptin action is sufficient to restore euglycemia in insulinopenic type 1 diabetes (T1D); however, the underlying mechanism remains poorly understood. To examine the role of intracellular signal transducer and activator of transcription 3 (STAT3) pathways, we used LepRs/s mice with disrupted leptin-phosphorylated STAT3 signaling to test the effect of central leptin on euglycemia restoration. These mice developed streptozocin-induced T1D, which was surprisingly not associated with hyperglucagonemia, a typical manifestation in T1D. Further, leptin action on euglycemia restoration was abrogated in these mice, which was associated with refractory hypercorticosteronemia. To examine the role of fast-acting neurotransmitters glutamate and γ-aminobutyric acid (GABA), two major neurotransmitters in the brain, from leptin receptor (LepR) neurons, we used mice with disrupted release of glutamate, GABA, or both from LepR neurons. Surprisingly, all mice responded normally to leptin-mediated euglycemia restoration, which was associated with expected correction from hyperglucagonemia and hyperphagia. In contrast, mice with loss of glutamate and GABA appeared to develop an additive obesity effect over those with loss of single neurotransmitter release. Thus, our study reveals that STAT3 signaling, but not fast-acting neurotransmitter release, is required for leptin action on euglycemia restoration and that hyperglucagonemia is not required for T1D.

A sensitive and practical RP-HPLC-FLD for determination of the low neuroactive amino acid levels in body fluids and its application in depression

Ion-exchange high performance liquid chromatography (HPLC) generally fails as a method to determine low levels of free amino acids (AAs) in body fluids. Here we present a modified reversed-phase HPLC (RP-HPLC) protocol for the determination of AAs in body fluids and its application in mood disorder patients. We improved a previous research protocol by modifying i) sample preparation, including deproteination, ii) derivitization, including derivating agent and condition, and iii) sample separation, which is mainly determined by the pH value, the components and the additives of the mobile phases. The combination of these modifications, together with fluorescence detection (FLD), allows sensitive and practical determination of free AA levels in body fluids of depressive patients. This protocol was validated by determining the postmortem cerebrospinal fluid (CSF) glutamic acid (Glu) and γ-aminobutyric acid (GABA) levels of 8 major depressive disorder (MDD) patients, 9 bipolar disorder (BD) patients, and 19 well-matched controls, while also testing the plasma and CSF AA levels of living MDD patients. CSF Glu and GABA levels were both significantly decreased in MDD but not in BD patients. The data indicate that this RP-HPLC-FLD protocol is applicable for detection of low levels of neuroactive AAs in body fluids, as well as for routine clinical applications.

Editorial: Cytokines as Players of Neuronal Plasticity and Sensitivity to Environment in Healthy and Pathological Brain.

In this e-Book, we collected recent evidence on the role of cytokines (including chemokines) in the interplay between environmental stimulation and central responses in both physiological and pathological conditions. The e-Book includes original studies and review articles focused on cytokine function during brain development as well as in the mature brain. Cytokines, together with neurotransmitters and hormones, are signaling molecules playing a key role in the maintenance of neuro-immune-endocrine system homeostasis. The cytokine systems (constituted by cytokines, their receptors and regulators of their activity) are expressed throughout the brain and their expression is regulated during brain development until aging. Brain cells, including neurons as well as glia cells, can release and/or be responsive to cytokines, therefore these molecules can enable communication between different cell types. Under physiological conditions, cytokines typically participate in brain development and plasticity by translating environmental into molecular signals. However, once the allostatic equilibrium is compromised, cytokine systems, if over- or chronically-activated, may participate in mediating toxic effects in the brain. Indeed, a central role for cytokines in neuropsychiatric as well as neurodegenerative disorders is now well recognized. The major source of cytokines release in the brain is microglia cells that are actively involved in adult brain homeostasis and in neural loss and synaptic maturation during development. The contribution of Pagani et al. addresses the role of fractalkine (CX3CL1) signaling in the developmental profile of morphological features and physiological properties of microglia using mice lacking the fractalkine receptor (who is expresses only in microglia within the healthy brain). Sheridan et al. investigated the role for fractalkine in synaptic plasticity showing that the levels of hippocampal fractalkine increases after a memory task and that the chemokine regulates glutamate-mediated neurotransmission tone. A comprehensive review on the role of fractalkine in regulating microglia properties, brain plasticity and behavior is provided by Paolicelli et al.. Another cytokine known to modulate memory-related processes is interferon (IFN)-γ. One of the article included in this e-book describe the effects induced by the lack of IFN-γ on memory function under basal or stressful conditions (Litteljohn et al.). This study emphasizes the importance of considering the “brain state” (healthy or disease) when the modulation of neurobehavioral processes by the cytokine systems it is evaluated. Interestingly, in the commentary of von Bohlen and Halbach, the astrocytic secreted lipocalin 2 is described as a mediator of the dialogue between astrocytes and neuron that in turn affects synaptic plasticity. Neuroimmune factors are particularly relevant to a number of neurophatologies. They play important pro-survival and/or pro-death roles by regulating targets in specific brain regions. Sutinem et al. reported that in pathological conditions, such as Alzheimer's disease, the cytokine interleukin (IL)-18 seems potentially involved in driving protein changes relevant for the pathogenesis, whereas Chiavegato et al. described the role of IL-1 beta and the high mobility group B1 (HMGB1) in preventing seizure-like discharges in models of focal epilepsy. Cytokines affect brain functions through different molecular mechanisms. Groul et al. show that up-regualtion of astrocytic CCL2 and Il-6 differentially affect the levels of specific proteins in cerebellum and hippocampus. The review of Guyon described how the stimulation of the receptor CXCR4 by the chemokine CXCL12 regulates the synaptic release of glutamate and γ-aminobutyric acid (GABA). Calabrese et al. proposed the neurotrophin brain-derived neurotrophic factor (BDNF) as a bridge between increased levels of pro-inflammatory cytokines and impaired neuroplasticity while the contribution of Cattaneo et al. is centered on epigenetics mechanisms that, by altering inflammation-immune systems and neuronal plasticity, may increase vulnerability to develop psychiatric disorders following early life stressful events. Finally, in their review, Singhal et al. analyze the neuroimmune mechanisms associated with neurobiological and behavioral changes following different environmental stimulations. In particular, they described how environmental enrichment (mainly physical exercise) affects neuroimmune targets and behavior. Overall, the work presented herein provides an insight into important aspects of the role of neuroimmune factors on brain activity and behavior. It represent a small windows on a complex panorama that still remain to be fully elucidated, especially with regard to the interplay between cytokine action, environmental stimulation and neuronal outcome.

Chapter 12 - Anti-NMDAR encephalitis and other glutamate and GABA receptor antibody encephalopathies

Over the last few year, antibodies to various central nervous system receptors, particularly the glutamate and γ-aminobutyric acid (GABA) receptors, have been found to be associated with autoimmune neurologic disorders. The receptors include the N-methyl-d-aspartate receptor (NMDAR), the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), the metabotropic glutamate receptors (mGluRs), and GABA type A and B receptors (respectively GABAAR and GABABR). Compared to the previously described paraneoplastic antibodies directed at intracellular targets, the patients with receptor antibodies are often younger, they less frequently have malignancies, and they respond better to immunotherapy. Many of the patients have limbic encephalitis with amnesia, disorientation, seizures, and psychological or psychiatric symptoms, but those with NMDAR antibodies usually develop a more widespread form of encephalitis, often leading to a decrease in consciousness and requirement for long-term intensive care treatment. The autoantibodies bind directly to the synaptic or extrasynaptic receptors on the membrane surface, and have direct effects on signal transduction in central synapses. These conditions are very important to recognize as the symptoms and complications can be fatal when not treated in time, whereas with immunotherapy many patients recover considerably.

Anesthetic propofol normalized the increased release of glutamate and γ-amino butyric acid in hippocampus after paradoxical sleep deprivation in rats

Objective: Multiple lines of evidence suggest that general anesthesia helps the recovery from sleep deprivation. However, little is known about the underlying neurochemical mechanisms. In the current study, we investigated the effect of anesthetic propofol on the release of glutamate (Glu) and γ-amino butyric acid (GABA) in the hippocampal CA1 region of rat with 24 h-paradoxical sleep deprivation (PSD).Methods: A guide cannula for microdialysis was inserted into the CA1 region of hippocampus in rats. At six days after cannula implantation, rats received 24 h-PSD by using the platform–water tank method. The rats were then subjected to natural sleep or propofol anesthesia (100 mg/kg, i.p.), respectively, after 24-h PSD. Microdialysis samples from hippocampus were collected before and at the end of PSD, and also at 1, 3, 6, and 8 h post-PSD. The concentrations of Glu and GABA in collected samples were determined by using high performance liquid chromatography.Results: The current study showed that 24 h-PSD significantly increased the release of Glu and GABA in the hippocampus in rats. In both natural sleep and propofol anesthesia groups, the upregulated Glu and GABA levels after PSD gradually decreased and returned to the baseline level by 8 h post-PSD.Conclusion: Our data indicate that propofol anesthesia promotes the restoration of disturbed excitatory and inhibitory neurotransmitter release in the hippocampus after PSD, similar to the beneficial effects of natural sleep. This finding suggests that propofol anesthesia may be a viable pharmacotherapeutic strategy for the treatment of certain sleep disorders that share similar mechanisms with PSD.

Effects of the ornidazole enantiomers on the central nervous system: Involvement of the GABAA receptor

This is the preliminary study of the sedative and muscle relaxation activity of ornidazole enantiomers, which are widely used in the treatment of susceptible protozoal infections and anaerobic bacterial infections. Adverse effects on the central nervous system (CNS) are the main side effects of ornidazole during its clinical application. The aim of this study was to compare the different central inhibitory effects between S-(−) ornidazole and R-(+) ornidazole in mice and clarify the possible mechanisms. In the present study, central effects of ornidazole were evaluated by open-field test and rota-rod test, and such effects were reversed by pre-treatment with flumazenil (i.p., 10 mg/kg) suggesting that ornidazole exhibits such action by interacting with the GABAergic system. Then, the functional difference between S-(−) ornidazole and R-(+) ornidazole was further explored by evaluating the contents of glutamate (Glu) and γ-aminobutyric acid (GABA) in the brain, and Western blot was used to measure glutamic acid decarboxylase (GAD65/67) expression in the mice cerebral cortex. We found that R-(+) ornidazole mediated an increase in GABA level while decreased the level of glutamate through upregulation of GAD65/67 in the cerebral cortex. Taken together, our study suggests that R-(+) ornidazole mediate stronger central inhibitory effects than S-(−) ornidazole through interaction with the GABAergic system.

Proton Magnetic Resonance Spectroscopy: Relevance of Glutamate and GABA to Neuropsychology.

Proton Magnetic Resonance Spectroscopy (MRS) has been widely used to study the healthy and diseased brain in vivo. The availability of whole body MR scanners with a field strength of 3 Tesla and above permit the quantification of many metabolites including the neurotransmitters glutamate (Glu) and γ-aminobutyric acid (GABA). The potential link between neurometabolites identified by MRS and cognition and behavior has been explored in numerous studies both in healthy subjects and in patient populations. Preliminary findings suggest direct or opposite associations between GABA or Glu with impulsivity, anxiety, and dexterity. This chapter is intended to provide an overview of basic principles of MRS and the literature reporting correlations between GABA or Glu and results of neuropsychological assessments.

The modulatory effect of CA1 GABAb receptors on ketamine-induced spatial and non-spatial novelty detection deficits with respect to Ca2+

Glutamate and γ-aminobutyric acid (GABA) are among the most abundant neurotransmitters in the central nervous system. Ketamine and other noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonists are known to induce deficits in learning and the performance of cognitive tasks. The present study was designed to assess the effects of dorsal hippocampal (CA1) GABAb receptors on ketamine-induced spatial and non-spatial memory deficits with regard to the role of Ca2+ as a defining factor. Spatial and non-spatial novelty detection of male NMRI mice were investigated in a circular open-field apparatus. According to our results, the intraperitoneal injection of ketamine at its higher dose (0.1mg/kg) impaired both spatial and non-spatial novelty detection. Moreover, the intra-CA1 injection of baclofen (a GABAb receptor agonist) at higher doses (0.02 and 0.2μg/mouse) impaired the spatial but not non-spatial novelty detection. In addition, phaclofen (a GABAb receptor antagonist at 0.2μg/mouse) impaired both spatial and non-spatial novelty detection. Baclofen restored and induced a modulatory effect on ketamine-induced responses in the spatial and non-spatial novelty detection task, respectively. On the contrary, phaclofen restored and induced a modulatory effect on ketamine-induced responses in the non-spatial and spatial novelty detection task, respectively. Finally, the subthreshold dose of SKF96365 (a Ca2+ channel blocker) impaired only the spatial but not non-spatial restoration effects of baclofen or phaclofen following a higher dose of ketamine. Such findings suggest that the ketamine-induced impairment of memory consolidation may occur through GABAb receptors of the CA1 neurons. Moreover, baclofen and phaclofen were shown to possibly exert their effects on the ketamine-induced spatial novelty detection deficits through Ca2+ channels.

The effect of Mongolian medical acupuncture on cytokines and neurotransmitters in the brain tissue of insomniac rats

IntroductionMongolian medical acupuncture (MMA) is thought to have a significant therapeutic effect on insomnia. The effect of MMA on levels of interleukins (ILs) and neurotransmitters in insomniac rats was investigated and the potential mechanism operating for insomnia is discussed. MethodsSD rats in 6 groups (control group 1, control group 2, normal acupuncture group, insomnia group, insomnia+acupuncture group, and insomnia+Western medicine group) were intraperitoneally injected with p-chlorophenylalanine to provide an insomniac model. “Dinghui, Heyi and Xin acupoints” were stimulated with needles to observe the locomotor activities of insomniac rats (injected with pentobarbital sodium) and their sleep time. Levels of interleukin (IL)-1, IL-2, and IL-6, and tumor necrosis factor (TNF)-α in the brain prefrontal lobe cortex, hypothalamus, and hippocampus tissue were measured by enzyme linked immunosorbent assay. Noradrenaline (NE), dopamine (DA), 5-hydroxytryptamine (5-HT), glutamic acid (Glu) and γ-aminobutyric acid (GABA) levels were measured by HPLC-ECD, and acetyl choline (Ach) level was determined by HPLC-RE-ECD. ResultsInsomniac rats experienced quietness, reduced activities and recovery of sleep time, drinking and eating and mental state after MMA stimulation. MMA significantly prolonged the sleep time induced by pentobarbital sodium. Levels of IL-1, IL-2, IL-6 and TNF-α significantly increased compared with those of insomniac models (P<0.01). Levels of NE, DA, and Glu decreased significantly (P<0.01), whereas those of 5-HT, GABA, and Ach increased significantly (P<0.01). ConclusionsMMA significantly decreased the cerebral excitability of insomniac rats. It promoted sleep probably by regulating the contents of cytokines and neurotransmitters in brain tissues.

Anti-absence activity of mGlu1 and mGlu5 receptor enhancers and their interaction with a GABA reuptake inhibitor: Effect of local infusions in the somatosensory cortex and thalamus.

Glutamate and γ-aminobutyric acid (GABA) are the key neurotransmitter systems in the cortical-thalamocortical network, involved in normal and pathologic oscillations such as spike-wave discharges (SWDs), which characterize different forms of absence epilepsy. Metabotropic glutamate (mGlu) and GABA receptors are widely expressed within this network. Herein, we examined the effects of two selective positive allosteric modulators (PAMs) of mGlu1 and mGlu5 receptors, the GABA reuptake inhibitor, tiagabine, and their interaction in the somatosensory cortex and thalamus on SWDs in WAG/Rij rats. Male WAG/Rij rats were equipped with bilateral cannulas in the somatosensory cortex (S1po) or the ventrobasal (VB) thalamic nuclei, and with cortical electroencephalography (EEG) electrodes. Rats received a single dose of the mGlu1 receptor PAM, RO0711401, or the mGlu5 receptor PAM, VU0360172, various doses of tiagabine, or VU0360172 combined with tiagabine. Both PAMs suppressed SWDs regardless of the site of injection. Tiagabine enhanced SWDs when injected into the thalamus, but, unexpectedly, suppressed SWDs in a dose-dependent manner when injected into the cortex. Intracortical co-injection of VU0360172 and tiagabine produced slightly larger effects as compared to either VU0360172 or tiagabine alone. Intrathalamic co-injections of VU0360172 and subthreshold doses of tiagabine caused an antiabsence effect similar to that exhibited by VU0360172 alone in the first 10 min. At 30 min, however, the antiabsence effect of VU0360172 was prevented by subthreshold doses of tiagabine, and the combination produced a paradoxical proabsence effect at 40 and 50 min. These data (1) show that mGlu1 and mGlu5 receptor PAMs reduce absence seizures acting at both thalamic and cortical levels; (2) demonstrate for the first time that tiagabine, despite its established absence-enhancing effect, reduces SWDs when injected into the somatosensory cortex; and (3) indicate that the efficacy of VU0360172 in the thalamus may be critically affected by the availability of (extra)synaptic GABA.

Surface-Enhanced Raman Scattering Spectroscopy for the Detection of Glutamate and &lt;inline-formula&gt; &lt;tex-math notation="TeX"&gt;$\gamma$&lt;/tex-math&gt;&lt;/inline-formula&gt;-Aminobutyric Acid in Serum by Partial Least Squares Analysis

Glutamate (GLU) and γ-aminobutyric acid (GABA) are important amino acid neurotransmitters that, respectively, mediate rapid excitatory and inhibitory neurotransmission in the brain. Serum GLU and GABA levels could play a significant role in pathogenesis of the encephalopathic state, early detection of autism, and the neurobiology of depression. The optimal concentration ratio of GLU and GABA is vital for neuroendocrine control, and deviations in their synthesis are linked to epilepsy. Additionally, circulating GLU affects GABA levels in striatal extracellular fluid. The present work explores the feasibility of employing surface-enhanced Raman scattering spectroscopy, in conjunction with partial least squares (PLS) , for simultaneous measurement of physiological concentrations of GLU and GABA in their aqueous solution and blood serum. A PLS calibration model showed a high coefficient of determination (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> >0.98) between the spectral data of GLU and GABA and their respective concentrations. The low root mean square error of prediction (RMSEP) value was ~2.7 μM, and it established the accuracy of the calibration model. The present methodology enabled the detection of GLU and GABA as low as 8 μM. This provides a cost-effective alternative to existing techniques for quantification of neurotransmitters.

Vitamin D3 Supplemental Treatment for Mania in Youth with Bipolar Spectrum Disorders.

We aimed to determine the effect of an open-label 8 week Vitamin D3 supplementation on manic symptoms, anterior cingulate cortex (ACC) glutamate, and γ-aminobutyric acid (GABA) in youth exhibiting symptoms of mania; that is, patients with bipolar spectrum disorders (BSD). We hypothesized that an 8 week Vitamin D3 supplementation would improve symptoms of mania, decrease ACC glutamate, and increase ACC GABA in BSD patients. Single time point metabolite levels were also evaluated in typically developing children (TD). The BSD group included patients not only diagnosed with BD but also those exhibiting bipolar symptomology, including BD not otherwise specified (BD-NOS) and subthreshold mood ratings (Young Mania Rating Scale [YMRS] ≥8 and Clinical Global Impressions - Severity [CGI-S] ≥3). Inclusion criteria were: male or female participants, 6-17 years old. Sixteen youth with BSD exhibiting manic symptoms and 19 TD were included. BSD patients were asked to a take daily dose (2000 IU) of Vitamin D3 (for 8 weeks) as a supplement. Neuroimaging data were acquired in both groups at baseline, and also for the BSD group at the end of 8 week Vitamin D3 supplementation. Baseline ACC GABA/creatine (Cr) was lower in BSD than in TD (F[1,31]=8.91, p=0.007). Following an 8 week Vitamin D3 supplementation, in BSD patients, there was a significant decrease in YMRS scores (t=-3.66, p=0.002, df=15) and Children's Depression Rating Scale (CDRS) scores (t=-2.93, p=0.01, df=15); and a significant increase in ACC GABA (t=3.18, p=0.007, df=14). Following an 8 week open label trial with Vitamin D3, BSD patients exhibited improvement in their mood symptoms in conjunction with their brain neurochemistry.

Analysis of signal processing in vestibular circuits with a novel light-emitting diodes-based fluorescence microscope.

Optical visualization of neural network activity is limited by imaging system-dependent technical tradeoffs. To overcome these constraints, we have developed a powerful low-cost and flexible imaging system with high spectral variability and unique spatio-temporal precision for simultaneous optical recording and manipulation of neural activity of large cell groups. The system comprises eight high-power light-emitting diodes, a camera with a large metal-oxide-semiconductor sensor and a high numerical aperture water-dipping objective. It allows fast and precise control of excitation and simultaneous low noise imaging at high resolution. Adjustable apertures generated two independent areas of variable size and position for simultaneous optical activation and image capture. The experimental applicability of this system was explored in semi-isolated preparations of larval axolotl (Ambystoma mexicanum) with intact inner ear organs and central nervous circuits. Cyclic galvanic stimulation of semicircular canals together with glutamate- and γ-aminobutyric acid (GABA)-uncaging caused a corresponding modulation of Ca(2+) transients in central vestibular neurons. These experiments revealed specific cellular properties as well as synaptic interactions between excitatory and inhibitory inputs, responsible for spatio-temporal-specific sensory signal processing. Location-specific GABA-uncaging revealed a potent inhibitory shunt of vestibular nerve afferent input in the predominating population of tonic vestibular neurons, indicating a considerable impact of local and commissural inhibitory circuits on the processing of head/body motion-related signals. The discovery of these previously unknown properties of vestibular computations demonstrates the merits of our novel microscope system for experimental applications in the field of neurobiology.

R-Baclofen Reverses a Social Behavior Deficit and Elevated Protein Synthesis in a Mouse Model of Fragile X Syndrome.

Background:Fragile X syndrome (FXS) is the most common known inherited form of intellectual disability and the single genomic cause of autism spectrum disorders. It is caused by the absence of a fragile X mental retardation gene (Fmr1) product, FMRP, an RNA-binding translation suppressor. Elevated rates of protein synthesis in the brain and an imbalance between synaptic signaling via glutamate and γ-aminobutyric acid (GABA) are both considered important in the pathogenesis of FXS. In a mouse model of FXS (Fmr1 knockout [KO]), treatment with R-baclofen reversed some behavioral and biochemical phenotypes. A remaining crucial question is whether R-baclofen is also able to reverse increased brain protein synthesis rates.Methods:To answer this question, we measured regional rates of cerebral protein synthesis in vivo with the L-[1-14C]leucine method in vehicle- and R-baclofen–treated wildtype and Fmr1 KO mice. We further probed signaling pathways involved in the regulation of protein synthesis.Results:Acute R-baclofen administration corrected elevated protein synthesis and reduced deficits on a test of social behavior in adult Fmr1 KO mice. It also suppressed activity of the mammalian target of rapamycin pathway, particularly in synaptosome-enriched fractions, but it had no effect on extracellular-regulated kinase 1/2 activity. Ninety min after R-baclofen treatment, we observed an increase in metabotropic glutamate receptor 5 expression in the frontal cortex, a finding that may shed light on the tolerance observed in human studies with this drug.Conclusions:Our results suggest that treatment via activation of the GABA (GABA receptor subtype B) system warrants further study in patients with FXS.

Transepithelial resistance in human bestrophin-1 stably transfected Madin–Darby canine kidney cells

Bestrophin-1 (Best1) is a transmembrane protein, found in the basolateral plasma membrane of retinal pigmented epithelial cells. The exact structure and functions of Best1 protein are still unclear. The protein is thought to be a regulator of ion channels, or an ion channel itself: it was shown to be permeable for chloride, thiocyanate, bicarbonate, glutamate and γ-aminobutyric acid (GABA). Mutations in the gene for Best1 are leading to best vitelliform macular dystrophy (BVMD) and are found in several other types of maculopathy. In order to obtain additional information about Best1 protein, we determined cell polarization of a stably transfected Madin–Darby canine kidney cell line II (MDCK II) cell line, expressing human Best1. We measured the transepithelial resistance of transfected and non-transfected MDCK cells by voltmeter EVOM, over 10 days at 24 hour intervals. The first few days (first–fourth day) both cell lines showed the same or similar values ​​of transmembrane resistance. As expected, on the fifth day the non-transfected cells showed maximum value of epithelial resistance, corresponding to the forming of monolayer. The transfected cells showed maximum value of transepithelial resistance on the ninth day of their cultivation. Phalloidin staining of actin demonstrated the difference in actin arrangements between transfected and non-transfected cells due to Best1. As a consequence of actin rearrangement, Best1 strongly affects the transepithelial resistance of polarizing stably transfected MDCK cells. Our results suggest that Best1 protein has an effect on transepithelial resistance and actin rearrangements of polarized stably transfected MDCK cells.

Effects of endogenous melatonin on glutamate and GABA rhythms in the striatum of unilateral 6-hydroxydopamine-lesioned rats

We have previously reported a time-dependent increase in melatonin (MLT) and decrease in dopamine (DA) in striatal dialysate 3weeks after unilateral 6-hydroxydopamine (6-OHDA) lesioning in the rat substantia nigra pars compacta (SNc) and medial forebrain bundle (MFB). This study aimed to investigate dynamic and circadian variations in DA, MLT, glutamate (Glu) and γ-aminobutyric acid (GABA) in striatal dialysates in the same 6-OHDA animal model. These neurotransmitters were determined using high-performance liquid chromatography (HPLC). Three weeks following 6-OHDA lesioning, there was a significant increase in extracellular Glu (156%) and decrease in GABA (15%) and DA (85%) in the lesioned striatum. These changes continued over time. Concomitantly, MLT was increased by 107% in the lesioned striatal dialysates after 4weeks, and continued to increase gradually over time. Six weeks post-treatment, levels of MLT secretion at 12 time points were higher, and the peak time of MLT secretion was earlier, in 6-OHDA-lesioned rats compared with vehicle-treated rats. In addition, significant variations in extracellular levels of Glu and GABA between day and night were observed in vehicle-treated rat striatum. However, no circadian variations were observed in the striatum of unilateral 6-OHDA-lesioned rats. Six weeks post-treatment, MLT levels correlated well with Glu and GABA levels at corresponding time-points in the striatum ipsilateral to the injected side in both groups, and increased MLT levels also correlated well with changes in Glu and GABA in the striatum in 6-OHDA-lesioned rats. These data suggest that 6-OHDA lesioning affects the endogenous productions of DA, MLT, Glu and GABA, and changes the MLT secretion pattern. Augmented striatal MLT levels and advanced MLT secretion pattern caused by unilateral intracerebral injection of 6-OHDA may influence the variations in Glu and GABA between day and night.

In vivo magnetic resonance studies reveal neuroanatomical and neurochemical abnormalities in the serine racemase knockout mouse model of schizophrenia

BackgroundDecreased availability of the N-methyl-d-aspartate receptor (NMDAR) co-agonist d-serine is thought to promote NMDAR hypofunction and contribute to the pathophysiology of schizophrenia, including neuroanatomical abnormalities, such as cortical atrophy and ventricular enlargement, and neurochemical abnormalities, such as aberrant glutamate and γ-aminobutyric acid (GABA) signaling. It is thought that these abnormalities directly relate to the negative symptoms and cognitive impairments that are hallmarks of the disorder. Because of the genetic complexity of schizophrenia, animal models of the disorder are extremely valuable for the study of genetically predisposing factors. Our laboratory developed a transgenic mouse model lacking serine racemase (SR), the synthetic enzyme of d-serine, polymorphisms of which are associated with schizophrenia. Null mutants (SR−/−) exhibit NMDAR hypofunction and cognitive impairments. We used 9.4T magnetic resonance imaging (MRI) and proton spectroscopy (MRS) to compare in vivo brain structure and neurochemistry in wildtype (WT) and SR−/− mice. MethodsMice were anesthetized with isoflurane for MRI and MRS scans. ResultsCompared to WT controls, SR−/− mice exhibited 23% larger ventricular volumes (p<0.05). Additionally, in a medial frontal cortex voxel (15μl), SR−/− mice exhibited significantly higher glutamate/water (12%, t=1.83, p<0.05) and GABA/water (72%, t=4.10, p<0.001) ratios. ConclusionsCollectively, these data demonstrate in vivo neuroanatomical and neurochemical abnormalities in the SR−/− mouse comparable to those previously reported in humans with schizophrenia.