PDZ interaction of the GABA transporter GAT1 with the syntenin-1 in Neuro-2a cells.

The GABA transporter GAT1 regulates brain inhibitory neurotransmission and it is considered a potential therapeutic target for the treatment of wide spectrum of neurological diseases including epilepsy, stroke and autism. Syntenin-1 binds to syntaxin 1A, which is known to regulate the plasma membrane insertion of several neurotransmitter transporters. Previously, a direct interaction of syntenin-1 with the glycine transporter GlyT2 was reported. Here, we show that the GABA transporter GAT1 also directly interacts with syntenin-1, involving both unidentified protein interaction interface and the GAT1 C-terminal PDZ binding motif interacting mainly with syntenin-1 PDZ domain 1. The PDZ interaction was eliminated by the mutation of GAT1 isoleucine 599 and tyrosine 598 located in PDZ positions 0 and -1, respectively. This indicates an unconventional PDZ interaction and possible regulation of the transporter PDZ motif via tyrosine phosphorylation. Whole syntenin-1 protein fused to GST protein and immobilised on glutathione resin coprecipitated intact GAT1 transporter from an extract of GAT1 transfected neuroblastoma N2a cells. This coprecipitation was inhibited by tyrosine phosphatases inhibitor pervanadate. The fluorescence tagged GAT1 and syntenin-1 colocalized upon coexpression in N2a cells. The above results show that syntenin-1 might be, in addition to GlyT2, directly involved in the trafficking of GAT1 transporter.

Enhancing GAT-3 in thalamic astrocytes promotes resilience to brain injury in rodents.

Inflammatory processes induced by brain injury are important for recovery; however, when uncontrolled, inflammation can be deleterious, likely explaining why most anti-inflammatory treatments have failed to improve neurological outcomes after brain injury in clinical trials. In the thalamus, chronic activation of glial cells, a proxy of inflammation, has been suggested as an indicator of increased seizure risk and cognitive deficits that develop after cortical injury. Furthermore, lesions in the thalamus, more than other brain regions, have been reported in patients with viral infections associated with neurological deficits, such as SARS-CoV-2. However, the extent to which thalamic inflammation is a driver or by-product of neurological deficits remains unknown. Here, we found that thalamic inflammation in mice was sufficient to phenocopy the cellular and circuit hyperexcitability, enhanced seizure risk, and disruptions in cortical rhythms that develop after cortical injury. In our model, down-regulation of the GABA transporter GAT-3 in thalamic astrocytes mediated this neurological dysfunction. In addition, GAT-3 was decreased in regions of thalamic reactive astrocytes in mouse models of cortical injury. Enhancing GAT-3 in thalamic astrocytes prevented seizure risk, restored cortical states, and was protective against severe chemoconvulsant-induced seizures and mortality in a mouse model of traumatic brain injury, emphasizing the potential of therapeutically targeting this pathway. Together, our results identified a potential therapeutic target for reducing negative outcomes after brain injury.

Nonlinearities between inhibition and T-type calcium channel activity bidirectionally regulate thalamic oscillations.

Absence seizures result from 3 to 5 Hz generalized thalamocortical oscillations that depend on highly regulated inhibitory neurotransmission in the thalamus. Efficient reuptake of the inhibitory neurotransmitter GABA is essential, and reuptake failure worsens human seizures. Here, we show that blocking GABA transporters (GATs) in acute rat brain slices containing key parts of the thalamocortical seizure network modulates epileptiform activity. As expected, we found that blocking either GAT1 or GAT3 prolonged oscillations. However, blocking both GATs unexpectedly suppressed oscillations. Integrating experimental observations into single-neuron and network-level computational models shows how a non-linear dependence of T-type calcium channel gating on GABAB receptor activity regulates network oscillations. Receptor activity that is either too brief or too protracted fails to sufficiently open T-type channels necessary for sustaining oscillations. Only within a narrow range does prolonging GABAB receptor activity promote channel opening and intensify oscillations. These results have implications for therapeutics that modulate inhibition kinetics.

Combination of MS Binding Assays and affinity selection mass spectrometry for screening of structurally homogenous libraries as exemplified for a focused oxime library addressing the neuronal GABA transporter 1.

This study presents an efficient screening approach based on combination of mass spectrometry (MS) based binding assays (MS Binding Assays) and affinity selection mass spectrometry (ASMS) customized for screening of structurally homogeneous libraries sharing a common mass spectrometric fragmentation pattern. After reaction of a nipecotic acid derivative possessing a hydroxylamine functionality with aldehydes, the resulting oxime library was screened accordingly toward the GABA transporter subtype 1 (GAT1), a drug target for several neurological disorders. After assessing sublibraries' activities for inhibition of reporter ligand binding, hits in active ones were directly identified. This could be achieved by recording mass transitions for the reporter ligand as well as those predicted for the library components in a single LC-MS/MS run with a triple quadrupole mass spectrometer in the multiple reaction monitoring mode. Identification of hits with a predefined affinity could be reliably accomplished by calculation of IC50-values from specific binding concentrations of library constituents and reporter ligand. Application of this strategy revealed six hits, from which two of them were resynthesized for further biological evaluation. Thereby, the best one displayed a pKi of 7.38 in MS Binding Assays and a pIC50 of 6.82 in [3H]GABA uptake assays for GAT1.

Pharmacological activation of mGlu5 receptors with the positive allosteric modulator VU0360172, modulates thalamic GABAergic transmission.

Previous studies have shown that injection of the mGlu5 receptor positive allosteric modulator (PAM) VU0360172 into either the thalamus or somatosensory cortex markedly reduces the frequency of spike-and-wave discharges (SWDs) in the WAG/Rij model of absence epilepsy. Here we have investigated the effects of VU0360172 on GABA transport in the thalamus and somatosensory cortex, as possible modes of action underlying the suppression of SWDs. Systemic VU0360172 injections increase GABA uptake in thalamic synaptosomes from epileptic WAG/Rij rats. Consistent with this observation, VU0360172 could also enhance thalamic GAT-1 protein expression, depending on the dosing regimen. This increase in GAT-1 expression was also observed in the thalamus from non-epileptic rats (presymptomatic WAG/Rij and Wistar) and appeared to occur selectively in neurons. The tonic GABAA receptor current present in ventrobasal thalamocortical neurons was significantly reduced by VU0360172 consistent with changes in GAT-1 and GABA uptake. The in vivo effects of VU0360172 (reduction in tonic GABA current and increase in GAT-1 expression) could be reproduced in vitro by treating thalamic slices with VU0360172 for at least 1 h and appeared to be dependent on the activation of PLC. Thus, the effects of VU0360172 do not require an intact thalamocortical circuit. In the somatosensory cortex, VU0360172 reduced GABA uptake but did not cause significant changes in GAT-1 protein levels. These findings reveal a novel mechanism of regulation mediated by mGlu5 receptors, which could underlie the powerful anti-absence effect of mGlu5 receptor enhancers in animal models.

Oral Administration of Sargassum horneri Improves the HDM/DNCB-Induced Atopic Dermatitis in NC/Nga Mice.

The present study investigated the protective effects of Sargassum horneri (S. horneri) ethanol extract (SHE) against atopic dermatitis (AD), known as an abnormal immune response in house dust mite (HDM)/2,4-dinitrochlorobenzene (DNCB)-stimulated NC/Nga mice. The oral administration of SHE attenuated the AD symptoms, including the skin dermatitis severity, transepidermal water loss (TEWL), and ear edema in HDM/DNCB-stimulated mice. Moreover, the histological analysis revealed that SHE improved epidermal hyperplasia and hyperkeratosis, and reduced the dermal infiltrations of mast cells and eosinophils. Moreover, SHE downregulated the expression levels of cytokines (interleukin (IL)-6, IL-10, and interferon (IFN)-γ) and chemokines (Regulated on Activation, Normal T Cell Expressed and Secreted (RANTES), Eotaxin, and Thymus and activation-regulated chemokine (TARC)) by decreasing the expression levels of atopic initiators (IL-25 and IL-33) in HDM/DNCB-stimulated skin. The oral administration of SHE decreased the spleen size, reducing expression levels of AD-related cytokines (IL-4, IL-5, IL-6, IL-10, IL-13, IFN-γ, and TARC) by regulating the expressions of Tbx21 (T-bet), GATA Binding Protein 3 (GATA-3), and Signal transducer and activator of transcription 3 (STAT3). Moreover, SHE significantly attenuated the serum immunoglobulin (Ig)G1 and IgG2a levels in HDM/DNCB-stimulated mice. Collectively, these results suggest that S. horneri could be an ingredient of functional food against abnormal immune response.

A Proline Derivative-Enriched Fraction from Sideroxylon obtusifolium Protects the Hippocampus from Intracerebroventricular Pilocarpine-Induced Injury Associated with Status Epilepticus in Mice.

The N-methyl-(2S,4R)-trans-4-hydroxy-l-proline-enriched fraction (NMP) from Sideroxylon obtusifolium was evaluated as a neuroprotective agent in the intracerebroventricular (icv) pilocarpine (Pilo) model. To this aim, male mice were subdivided into sham (SO, vehicle), Pilo (300 µg/1 µL icv, followed by the vehicle per os, po) and NMP-treated groups (Pilo 300 µg/1 µL icv, followed by 100 or 200 mg/kg po). The treatments started one day after the Pilo injection and continued for 15 days. The effects of NMP were assessed by characterizing the preservation of cognitive function in both the Y-maze and object recognition tests. The hippocampal cell viability was evaluated by Nissl staining. Additional markers of damage were studied-the glial fibrillary acidic protein (GFAP) and the ionized calcium-binding adaptor molecule 1 (Iba-1) expression using, respectively, immunofluorescence and western blot analyses. We also performed molecular docking experiments revealing that NMP binds to the γ-aminobutyric acid (GABA) transporter 1 (GAT1). GAT1 expression in the hippocampus was also characterized. Pilo induced cognitive deficits, cell damage, increased GFAP, Iba-1, and GAT1 expression in the hippocampus. These alterations were prevented, especially by the higher NMP dose. These data highlight NMP as a promising candidate for the protection of the hippocampus, as shown by the icv Pilo model.

Pharmacological Characterization of a Betaine/GABA Transporter 1 (BGT1) Inhibitor Displaying an Unusual Biphasic Inhibition Profile and Anti-seizure Effects.

Focal epileptic seizures can in some patients be managed by inhibiting γ-aminobutyric acid (GABA) uptake via the GABA transporter 1 (GAT1) using tiagabine (Gabitril®). Synergistic anti-seizure effects achieved by inhibition of both GAT1 and the betaine/GABA transporter (BGT1) by tiagabine and EF1502, compared to tiagabine alone, suggest BGT1 as a target in epilepsy. Yet, selective BGT1 inhibitors are needed for validation of this hypothesis. In that search, a series of BGT1 inhibitors typified by (1R,2S)-2-((4,4-bis(3-methylthiophen-2-yl)but-3-en-yl)(methyl)amino)cyclohexanecarboxylic acid (SBV2-114) was developed. A thorough pharmacological characterization of SBV2-114 using a cell-based [3H]GABA uptake assay at heterologously expressed BGT1, revealed an elusive biphasic inhibition profile with two IC50 values (4.7 and 556 µM). The biphasic profile was common for this structural class of compounds, including EF1502, and was confirmed in the MDCK II cell line endogenously expressing BGT1. The possibility of two binding sites for SBV2-114 at BGT1 was assessed by computational docking studies and examined by mutational studies. These investigations confirmed that the conserved residue Q299 in BGT1 is involved in, but not solely responsible for the biphasic inhibition profile of SBV2-114. Animal studies revealed anti-seizure effects of SBV2-114 in two mouse models, supporting a function of BGT1 in epilepsy. However, as SBV2-114 is apparent to be rather non-selective for BGT1, the translational relevance of this observation is unknown. Nevertheless, SBV2-114 constitutes a valuable tool compound to study the molecular mechanism of an emerging biphasic profile of BGT1-mediated GABA transport and the putative involvement of two binding sites for this class of compounds.

Effects of ascorbic acid treatment on developmental alterations in calcium-binding proteins and gamma-aminobutyric acid transporter 1 in the cerebellum of lead-exposed rats during pregnancy and lactation.

In the present study, we investigated the effects of lead (Pb) and ascorbic acid co-administration on rat cerebellar development. Female rats were randomly divided into the following groups: control, Pb, and Pb plus ascorbic acid (PA) groups. From one week prior to mating, female rats were administered Pb (0.3% Pb acetate in drinking water) and ascorbic acid (100 mg/kg, oral intubation). The chemical administration was stopped on postnatal day 21 when the morphology of the offspring's cerebellum is similar to that of the adult brain. The blood Pb level was significantly increased following long-term Pb exposure. Ascorbic acid reduced Pb levels in the dams and offspring. Nissl staining demonstrated that the number of Purkinje cells was significantly reduced following Pb exposure, while ascorbic acid ameliorated this effect in the cerebellum of the offspring. Calcium-binding proteins, such as calbindin, calretinin, and parvalbumin were commonly expressed in Purkinje cells, and Pb exposure and ascorbic acid treatment resulted in similar patterns of change, namely Pb-induced impairment and ascorbic acid-mediated amelioration. The gamma-aminobutyric acid transporter 1 (GABAT1) is expressed in the pinceau structure where the somata of Purkinje cells are entwined in inhibitory synapses. The number of GABAT1-immunoreactive synapses was reduced following Pb exposure, and ascorbic acid co-treatment prevented this effect in the cerebellar cortex. Therefore, it can be concluded that ascorbic acid supplementation to mothers during gestation and lactation may have potential preventive effects against Pb-induced impairments in the developing cerebellum via protection of inhibitory neurons and synapses.

MS-Based Screening of 5-Substituted Nipecotic Acid Derived Hydrazone Libraries as Ligands of the GABA Transporter†1.

A screening of compound libraries based on nipecotic acid derivatives with lipophilic residues attached to the scarcely explored 5-position of the core structure was used for the search of new inhibitors of the γ-aminobutyric acid (GABA) transporter 1 (mGAT1). The generated compound libraries, which were based on hydrazone chemistry commonly used in dynamic combinatorial chemistry but rendered pseudostatic, were screened for their binding affinities toward mGAT1 by means of MS Binding Assays. With nipecotic acid derived hydrazone rac-16 h [rac-(3R,5S)-{5-[(E)-2-{[5-(2-phenylethynyl)thiophen-2-yl]methylidene}hydrazin-1-yl]piperidine-3-carboxylic acid}-sodium chloride (1/2)], one hit was found and evaluated displaying sub-micromolar potency (pKi =6.62±0.04) and a noncompetitive interaction mode at mGAT1. By bearing a 5-(2-phenylethynyl)thiophen-2-yl residue attached to the 5-position of nipecotic acid via a three-atom spacer, compound rac-16 h contains a structural moiety so far unprecedented for these kinds of bioactive molecules, and complements novel 5-substituted nipecotic acid derived ligands of mGAT1 revealed in a recently published screening campaign. This new class of ligands, with an inhibition mode distinct from that of benchmark mGAT1 inhibitors, could serve as research tools for investigations of mGAT1-mediated GABA transport.

Novel Allosteric Ligands of γ-Aminobutyric Acid Transporter 1 (GAT1) by MS Based Screening of Pseudostatic Hydrazone Libraries.

This study describes the screening of dynamic combinatorial libraries based on nipecotic acid as core structure with substituents attached to the 5- instead of the common 1-position for the search of novel inhibitors of the GABA transporter GAT1. The generated pseudostatic hydrazone libraries included a total of nearly 900 compounds and were screened for their binding affinities toward GAT1 in competitive mass spectrometry (MS) based Binding Assays. Characterization of the hydrazones with the highest affinities (with cis-configured rac-16gf bearing a 5-(1-naphthyl)furan-2-yl residue and a four atom spacer being the most potent) in binding and uptake experiments revealed an allosteric interaction at GAT1, which was not reported for any other nipecotic acid derivative up to now. Therefore, the herein introduced 5-substituted nipecotic acid derivatives could serve as valuable tools for investigations of allosterically modulated GABA transport mediated by GAT1 and furthermore as starting point for a new class of GAT1 inhibitors.

Beta-adrenergic receptor activation increases GABA uptake in adolescent mice frontal cortex: Modulation by cannabinoid receptor agonist WIN55,212-2.

GABA transporters regulate synaptic GABA levels and dysfunctions in this system might result in psychiatric disorders. The endocannabinoid system (ECS) is the main circuit breaker in the nervous system and may alter noradrenaline (NA) communication, which in turn modulates the release of GABA. However, a close relationship between these systems has not been recognized. We asked whether NA and ECS might control extracellular GABA levels in slices of frontal cortex (FC) of adolescent Swiss mice with 40 days after birth (PN40). Here we show that NA and isoproterenol (ISO), a beta-adrenergic agonist, increased [3H]-GABA uptake in mice FC, while alpha1-adrenergic agonist phenylephrine had no effect. As GAT-1 is expressed and fully functional at the FC, addition of NO-711, a GAT-1 inhibitor, dose dependently blocked [3H]-GABA uptake. The increase of [3H]-GABA uptake induced by ISO was also blocked by NO-711. [3H]-GABA release induced by 80 mM KCl was reduced by NO-711, but not by removal of Ca2+. ISO also increased cyclic AMP (cAMP) levels and addition of WIN 55,212-2, a mixed CB1/CB2 receptor agonist, inhibited the effect of ISO in GABA uptake increase, GAT-1 expression and cAMP levels compared to control. Our data show that GABA transport increased by NA and ISO is negatively regulated by cannabinoid receptor agonist WIN55,212-2.

Short-term mastication after weaning upregulates GABAergic signalling and reduces dendritic spine in thalamus.

Mastication enhances brain function and mental health, but little is known about the molecular mechanisms underlying the effects of mastication on neural development in early childhood. Therefore, we analysed the gene expression in juvenile neural circuits in rats fed with a soft or chow diet immediately after weaning. We observed that the gene expression patterns in the thalamus varied depending on the diet. Furthermore, gene ontology analysis revealed that two terms were significantly enhanced: chemical synaptic transmission and positive regulation of dendritic spine morphogenesis. With respect to chemical synaptic transmission, glutamate decarboxylase and GABA receptors were upregulated in the chow diet group. The related genes, including vesicular GABA transporter, were also upregulated, suggesting that mastication activates GABAergic signalling. With respect to dendritic spine morphogenesis, Ingenuity Pathway Analysis predicted fewer extension of neurites and neurons and fewer number of branches in the chow diet group. The numbers of spines in the ventral posterolateral and posteromedial regions were significantly decreased. These results suggest that mastication in the early developing period upregulates GABAergic signalling genes, with a decrease of spines in the thalamus.

Dissociation of nNOS from PSD-95 promotes functional recovery after cerebral ischaemia in mice through reducing excessive tonic GABA release from reactive astrocytes.

Mechanisms underlying functional recovery after stroke are little known, and effective drug intervention during the delayed stage is desirable. One potential drug target, the protein-protein interaction between neuronal nitric oxide synthase (nNOS) and postsynaptic density protein 95 (PSD-95), is critical to acute ischaemic damage and neurogenesis. We show that nNOS-PSD-95 dissociation induced by microinjection of a recombinant fusion protein, Tat-nNOS-N1-133 , or systemic administration of a small-molecule, ZL006, from day 4 to day 10 after photothrombotic ischaemia in mice reduced excessive tonic inhibition in the peri-infarct cortex and ameliorated motor functional outcome. We also demonstrated improved neuroplasticity including increased dendrite spine density and synaptogenesis after reducing excessive tonic inhibition by nNOS-PSD-95 dissociation. Levels of gamma-aminobutyric acid (GABA) and GABA transporter-3/4 (GAT-3/4) are increased in the reactive astrocytes in the peri-infarct cortex. The GAT-3/4-selective antagonist SNAP-5114 reduced tonic inhibition and promoted function recovery, suggesting that increased tonic inhibition in the peri-infarct cortex was due to GABA release from reversed GAT-3/4 in reactive astrocytes. Treatments with Tat-nNOS-N1-133 or ZL006 after ischaemia inhibited astrocyte activation and GABA production, prevented the reversal of GAT-3/4, and consequently decreased excessive tonic inhibition and ameliorated functional outcome. The underlying molecular mechanisms were associated with epigenetic inhibition of glutamic acid decarboxylase 67 and monoamine oxidase B expression through reduced NO production. The nNOS-PSD-95 interaction is thus a potential target for functional restoration after stroke and ZL006, a small molecule inhibitor of this interaction, is a promising pharmacological lead compound. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Consequences of perinatal hypoxia in developing brain: Changes in GABA transporter functioning in cortical, hippocampal and thalamic rat nerve terminals.

Perinatal hypoxia leads to behavioral abnormalities, cognitive disabilities, and epilepsy resulting from alterations in neurodevelopment, maturation and construction of the network. Considering a particular role of γ-aminobutyric acid (GABA) for an immature brain, we analysed transporter-mediated [3H]GABA uptake in the cortical, hippocampal and thalamic nerve terminals isolated from rats of different age in the control and after perinatal hypoxia. The state of hypoxia was induced by exposure of rats at the age of 10 postnatal days (pd) (that corresponds approximately to the time of birth in humans) to a respiratory medium with low O2 content (4% O2 and 96%N2) for 12min (up to the initiation of clonico-tonic seizures). Here, we found that the initial rate of [3Н]GABA uptake was higher in the young rats (pd 17-19) as compared to the older ones (pd 24-26, 38-40 and 66-73) in both control and hypoxia groups. It decreased abruptly by 50% in the thalamus and by 25% in the cortex for the period from pd 17-19 to pd 66-73. In the hippocampus, a decrease in the rate during the same time interval was 25%. Exposure to hypoxia had no effect on the intensity of [3Н]GABA uptake by the cortical and thalamic nerve terminals, but caused a significant age-dependent attenuation (by 35%) of the uptake intensity in the hippocampal ones. Significant age-dependent hypoxia-independent decrease in [3Н]GABA uptake with step-like dynamics of changes was shown in the thalamus and cortex. Gradual age-dependent hypoxia-dependent decrease in [3Н]GABA uptake was revealed in the hippocampus, and so a particular vulnerability of the latest structure to hypoxia as compared to the cortex and thalamus was revealed.

Mechanisms of Chinese Medicine Xinmailong's protection against heart failure in pressure-overloaded mice and cultured cardiomyocytes.

Patients with heart failure (HF) have high mortality and mobility. Xinmailong (XML) injection, a Chinese Medicine, is clinically effective in treating HF. However, the mechanism of XML's effectiveness on HF was unclear, and thus, was the target of the present study. We created a mouse model of pressure-overload-induced HF with transverse aortic constriction (TAC) surgery and compared among 4 study groups: SHAM (n = 10), TAC (n = 12), MET (metoprolol, positive drug treatment, n = 7) and XML (XML treatment, n = 14). Dynamic changes in cardiac structure and function were evaluated with echocardiography in vivo. In addition, H9C2 rat cardiomyocytes were cultured in vitro and the phosphorylation of ERK1/2, AKT, GSK3ß and protein expression of GATA4 in nucleus were detected with Western blot experiment. The results showed that XML reduced diastolic thickness of left ventricular posterior wall, increased ejection fraction and fraction shortening, so as to inhibit HF at 2 weeks after TAC. Moreover, XML inhibited the phosphorylation of ERK1/2, AKT and GSK3ß, subsequently inhibiting protein expression of GATA4 in nucleus (P < 0.001). Together, our data demonstrated that XML inhibited the TAC-induced HF via inactivating the ERK1/2, AKT/GSK3ß, and GATA4 signaling pathway.

Tackling guanidinoacetic acid for advanced cellular bioenergetics.

Tissues with high-energy output, such as the brain and skeletal muscle, suffer the most from impaired or depleted energy levels, with innovative nutritional approaches needed to effectively tackle metabolic deficits in bioenergetics. Here, we highlight the role of guanidinoacetic acid in the control and provision of cellular energy by its interaction with cellular transporters for taurine (SLC6 A6) and γ-aminobutyric acid (SLC6 A13), previously dismissed as "untargetable" carriers by other bioenergetics therapeutics.

Neurotoxicity screening of (illicit) drugs using novel methods for analysis of microelectrode array (MEA) recordings.

Annual prevalence of the use of common illicit drugs and new psychoactive substances (NPS) is high, despite the often limited knowledge on the health risks of these substances. Recently, cortical cultures grown on multi-well microelectrode arrays (mwMEAs) have been used for neurotoxicity screening of chemicals, pharmaceuticals, and toxins with a high sensitivity and specificity. However, the use of mwMEAs to investigate the effects of illicit drugs on neuronal activity is largely unexplored. We therefore first characterised the cortical cultures using immunocytochemistry and show the presence of astrocytes, glutamatergic and GABAergic neurons. Neuronal activity is concentration-dependently affected following exposure to six neurotransmitters (glutamate, GABA, serotonin, dopamine, acetylcholine and nicotine). Most neurotransmitters inhibit neuronal activity, although glutamate and acetylcholine transiently increase activity at specific concentrations. These transient effects are not detected when activity is determined during the entire 30min exposure window, potentially resulting in false-negative results. As expected, exposure to the GABAA-receptor antagonist bicuculline increases neuronal activity. Exposure to a positive allosteric modulator of the GABAA-receptor (diazepam) or to glutamate receptor antagonists (CNQX and MK-801) reduces neuronal activity. Further, we demonstrate that exposure to common drugs (3,4-methylenedioxymethamphetamine (MDMA) and amphetamine) and NPS (1-(3-chlorophenyl)piperazine (mCPP), 4-fluoroamphetamine (4-FA) and methoxetamine (MXE)) decreases neuronal activity. MXE most potently inhibits neuronal activity with an IC50 of 0.5µM, whereas 4-FA is least potent with an IC50 of 113µM. Our data demonstrate the importance of analysing neuronal activity within different time windows during exposure to prevent false-negative results. We also show that cortical cultures grown on mwMEAs can successfully be applied to investigate the effects of different (illicit) drugs on neuronal activity. Compared to investigating multiple single endpoints for neurotoxicity or neuromodulation, such as receptor activation or calcium channel function, mwMEAs can provide information on integrated aspects of drug-induced neurotoxicity more rapidly. Therefore, this approach could contribute to a faster insight in possible health risks and shorten the regulation process.

Efficient production of gamma-aminobutyric acid using Escherichia coli by co-localization of glutamate synthase, glutamate decarboxylase, and GABA transporter.

Gamma-aminobutyric acid (GABA) is an important bio-product, which is used in pharmaceutical formulations, nutritional supplements, and biopolymer monomer. The traditional GABA process involves the decarboxylation of glutamate. However, the direct production of GABA from glucose is a more efficient process. To construct the recombinant strains of Escherichia coli, a novel synthetic scaffold was introduced. By carrying out the co-localization of glutamate synthase, glutamate decarboxylase, and GABA transporter, we redirected the TCA cycle flux to GABA pathway. The genetically engineered E. coli strain produced 1.08 g/L of GABA from 10 g/L of initial glucose. Thus, with the introduction of a synthetic scaffold, we increased GABA production by 2.2-fold. The final GABA concentration was increased by 21.8% by inactivating competing pathways.

Kava for the treatment of generalised anxiety disorder (K-GAD): study protocol for a randomised controlled trial.

BACKGROUND: Generalised anxiety disorder (GAD) is a chronic and pervasive condition that generates high levels of psychological stress, and it is difficult to treat in the long term. Current pharmacotherapeutic options for GAD are in some cases only modestly effective, and may elicit undesirable side effects. Through targeted actions on the gamma-aminobutyric acid (GABA) pathway, the South Pacific medicinal plant kava (Piper methysticum) is a non-addictive, non-hypnotic anxiolytic with the potential to treat GAD. The evidence for the efficacy of kava for treating anxiety has been affirmed through clinical trials and meta-analyses. Recent research has also served to lessen safety concerns regarding the use of kava due to hepatotoxic risk, which is reflected in a recent German court overturning the previous kava ban in that country (which may in turn influence a reinstatement by the European Union). The aim of current research is to assess the efficacy of an 'aqueous noble cultivar rootstock extract' of kava in GAD in a larger longer term study. In addition, we plan to investigate the pharmacogenomic influence of GABA transporters on response, effects of kava on gene expression, and for the first time, the neurobiological correlates of treatment response via functional and metabolic imaging. METHODS/DESIGN: This clinical trial is funded by the Australian National Health and Medical Research Council (APP1063383) and co-funded by MediHerb (Integria Healthcare (Australia) Pty. Ltd). The study is a phase III, multi-site, two-arm, 18-week, randomised, double-blind, placebo-controlled study using an aqueous extract of noble kava cultivar (standardised to 240 mg of kavalactones per day) versus matching placebo in 210 currently anxious participants with diagnosed GAD who are non-medicated. The study takes place at two sites: the Centre for Human Psychopharmacology (Swinburne University of Technology), Hawthorn, Melbourne, Australia; and the Academic Discipline of Psychiatry (The University of Queensland) based at the Royal Brisbane and Women's Hospital, Herston, Brisbane, Australia. Written informed consent will be obtained from each participant prior to commencement in the study. The primary outcome is the Structured Interview Guide for the Hamilton Anxiety Rating Scale (SIGH-A). The secondary outcomes involve a range of scales that assess affective disorder symptoms and quality of life outcomes, in addition to the study of mediating biomarkers of response (assessed via genomics and neuroimaging). DISCUSSION: If this study demonstrates positive findings in support of the superiority of kava over placebo in the treatment of GAD, and also is shown to be safe, then this plant-medicine can be considered a 'first-line' therapy for GAD. Genomic and neuroimaging data may reveal clinical response patterns and provide more evidence of the neurobiological activity of the plant extract. TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov: NCT02219880 Date: 13 August 2014:.