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The current opioid crisis has had an unprecedented public health impact. Approved medications for opioid use disorder (OUD) exist, yet their limitations indicate a need for innovative treatments. Limited preliminary clinical studies suggest specific psychedelics might aid OUD treatment, though most clinical evidence remains observational, with few controlled trials. This review aims to bridge the gap between preclinical findings and potential clinical applications, following PRISMA-ScR guidelines. Searches included MEDLINE, Embase, Scopus, and Web of Science, focusing on preclinical in vivo studies involving opioids and psychedelics in animals, excluding pain studies and those lacking control groups. Forty studies met criteria, covering both classic and non-classic psychedelics. Most studies showed that 18-methoxycoronaridine (18-MC), ibogaine, noribogaine, and ketamine could reduce opioid self-administration, alleviate withdrawal symptoms, and change conditioned place preference. However, seven studies (two on 2,5-dimethoxy-4-methylamphetamine (DOM), three on ibogaine, one on 18-MC, and one on ketamine) showed no improvement over controls. A methodological quality assessment rated most of the studies as having unclear quality. Interestingly, most preclinical studies are limited to iboga derivatives, which were effective, but these agents may have higher cardiovascular risk than other psychedelics under-explored to date. This review strengthens support for translational studies testing psychedelics as potential innovative targets for OUD. It also suggests clinical studies need to include a broader range of agents beyond iboga derivatives but can also explore several ongoing questions in the field, such as the mechanism of action behind the potential therapeutic effect, safety profiles, doses, and frequency of administrations needed. [ABSTRACT FROM AUTHOR]

Hemodialysis patients are susceptible to excess volume accumulation, particularly over the 2-day interval (long interdialytic gap), resulting in higher interdialytic weight gain (IDWG). We thought to determine whether a novel device designed to enhance fluid and salt loss by activating the eccrine sweat glands can mitigate IDWG. Patients eligible for the study were undergoing regular hemodialysis for ≥3 months, without residual renal function, and with IDWG (as a percentage of IDWG/dry body weight) ≥2.5%. Treatments were administered at the patient’s home. The primary performance endpoint was differences in weight gain over long interdialytic period with the device compared to the control period. Secondary exploratory endpoints included the need for ultrafiltration (UF) rate > 10 mL/kg/h in the post-interval dialysis. Five patients were enrolled into the pilot study (age range 26 to 69 years, 3 women). The hourly mean weight loss from sweat was 186 ± 45 g/h. The average procedure length was 4.5 h with an average fluid loss of 899 ± 283 grams per procedure. The average least-squares mean absolute difference of IDWG between the control and treatment periods was −2.0%; (95% confidence interval [CI], −2.9% to −1.2%, p < 0001). The reduction in IDWG was associated a reduction in UF rates, from 9.23 ± 3.7 mL/kg/h to 5.55 ± 2.45 mL/kg/h between the control and treatment periods (p < 0.001), resulting in a safe UF rate (<10 mL/kg/h) in all post-treatment sessions. We conclude that enhancing sweat rate can mitigate IDWG in hemodialysis patients. [ABSTRACT FROM AUTHOR]

Here we report and validate a simple method for measuring intracellular activities of glial glutamine synthetase (GS) and glutaminase (GLNase) in intact glial cells. These enzymes are responsible for glutamate and glutamine recycling in the brain, where glutamate and glutamine transport from the blood stream is strongly limited by the blood-brain barrier. The intracellular levels of glutamate and glutamine are dependent on activities of numerous enzymatic processes, including 1) cytosolic production of glutamine from glutamate by GS, 2) production of glutamate from glutamine by GLNase that is primarily localized between mitochondrial membranes, and 3) mitochondrial conversion of glutamate to the tricarboxylic cycle intermediate α-ketoglutarate in the reactions of oxidative deamination and transamination. We measured intracellular activities of GS and GLNase by quantifying enzymatic interconversions of L-[(3)H]glutamate and L-[(3)H]glutamine in cultured rat astrocytes. The intracellular substrate and the products of enzymatic reactions were separated in one step using commercially available anion exchange columns and quantified using a scintillation counter. The involvement of GS and GLNase in the conversion of (3)H-labeled substrates was verified using irreversible pharmacological inhibitors for each of the enzymes and additionally validated by measuring intracellular amino acid levels using an HPLC. Overall, this paper describes optimized conditions and pharmacological controls for measuring GS and GLNase activities in intact glial cells.

Background and Purpose: Increased activation of excitatory amino acid (EAA) receptors is considered a major cause of neuronal damage. Possible sources and mechanisms of ischemia-induced EAA release were investigated pharmacologically with microdialysis probes placed bilaterally in rat striatum., Methods: Forebrain ischemia was induced by bilateral carotid artery occlusion and controlled hypotension in halothane-anesthetized rats. During 30 minutes of ischemia, microdialysate concentrations of glutamate and aspartate were measured in the presence of a nontransportable blocker of the astrocytic glutamate transporter GLT-1, dihydrokinate (DHK), or an anion channel blocker, 4,4'-dinitrostilben-2,2'-disulfonic acid (DNDS), administered separately or together through the dialysis probe., Results: In control striata during ischemia, glutamate and aspartate concentrations increased 44+/-13 (mean+/-SEM) times and 19+/-5 times baseline, respectively, and returned to baseline values on reperfusion. DHK (1 mmol/L in perfusate; n=8) significantly attenuated EAA increases compared with control (glutamate peak, 9. 6+/-1.7 versus control, 15.4+/-2.6 pmol/ microL). EAA levels were similarly decreased by 10 mmol/L DHK. DNDS (1 mmol/L; n=5) also suppressed EAA peak increases (glutamate peak, 5.8+/-1.1 versus control, 10.1+/-0.7 pmol/ microL). At a higher concentration, DNDS (10 mmol/L; n=7) further reduced glutamate and aspartate release and also inhibited ischemia-induced taurine release. Together, 1 mmol/L DHK and 10 mmol/L DNDS (n=5) inhibited 83% of EAA release (glutamate peak, 2.7+/-0.7 versus control, 10.9+/-1.2 pmol/ microL)., Conclusions: These findings support the hypothesis that both cell swelling-induced release of EAAs and reversal of the astrocytic glutamate transporter are contributors to the ischemia-induced increases of extracellular EAAs in the striatum as measured by microdialysis.

Dopaminergic control over striatal targets appears to be retained in rats sustaining lesions of the nigrostriatal dopamine (DA) system as long as 5-10% of that projection remains. Similarly, during postnatal development, dopaminergic control over striatal neurons matures well before the innervation of striatum by the nigrostriatal bundle is attained. These observations suggest that enhanced efficacy of dopaminergic transmission may compensate for hypoinnervation of striatum after lesions or during development. To examine this hypothesis, striatal slices were superfused with Krebs bicarbonate buffer and effluent was collected and analyzed for endogenous DA. Electrical field stimulation (2 Hz) continuously delivered to slices prepared from intact adult rats increased DA efflux to 3-5 times the prestimulation rate within 10 min. Efflux then fell to approximately twice the basal rate over the next 20 min. DA efflux was also examined using slices prepared from adult animals given 6-hydroxydopamine 2-3 weeks earlier, and from 7-10-d-old rat pups. In each group, striatal DA levels were 10-40% of adult control values. Nevertheless, stimulated DA efflux from these slices attained the same rate as that observed with intact, adult slices. Thus, fractional DA efflux from these slices was several times higher than the control rate by the end of the stimulation period. This increased DA efflux appeared to be a consequence of both increased release and decreased reuptake of DA, as the fractional DA efflux from control striatal slices could not be increased to the rate seen in hypoinnervated slices using nomifensine (10 microM), an inhibitor of DA efflux.(ABSTRACT TRUNCATED AT 250 WORDS)

Stroke is a common and serious nervous system disease caused by the rupture or blockage of the cardiovascular system. It causes millions of deaths and disabilities every year, which is a huge burden on humanity. It may be induced by thrombosis, hypertension, hyperlipidemia, hyperglycemia, smoking, advanced age and so on. According to different causes, stroke can be generally divided into hemorrhagic stroke and ischemic stroke, whose pathogenesis and treatment are quite different. Ferroptosis is a new type of cell death first defined in 2012, which is characterized by non-apoptotic, iron-dependent, and over-accumulated lipid peroxides. Excess lipid reactive oxygen species produced during ferroptosis eventually leads to oxidative cell death. Ferroptosis has been shown to occur and play an important role in tumors, neurological diseases, kidney injury, and ischemia–reperfusion injury. Ferroptosis is also closely related to the pathogenesis of stroke. Moreover, scientists have successfully intervened in the process of stroke in animal models by regulating ferroptosis, indicating that ferroptosis is a new potential target for the treatment of stroke. This paper systematically summarizes the involvement and role of ferroptosis in the pathogenesis of stroke and predicts the potential of ferroptosis in the treatment of stroke. Ferroptosis in stroke. Stroke induces iron overload and lipid metabolism disorders. Elevated iron catalyzes lipid peroxidation and eventually triggers ferroptosis. Conversely, the GSH/GPX4 pathway, as well as CoQ10, Fer-1, and Lip-1, inhibits lipid peroxidation and, thus, alleviates ferroptosis. GSH glutathione; GPX4 glutathione peroxidase 4; CoQ10 coenzyme Q10; Lip-1 liproxstatin-1; Fer-1 ferostatin-1. [ABSTRACT FROM AUTHOR]

Background Between unaffected mental health and diagnosable psychiatric disorders, there is a vast continuum of functioning. The hypothesized link between striatal dopamine signaling and psychosis has guided a prolific body of research. However, it has been understudied in the context of multiple interacting factors, subclinical phenotypes, and pre-postsynaptic dynamics. Method This work investigated psychotic-like experiences and D2/3 dopamine postsynaptic receptor availability in the dorsal striatum, quantified by in vivo [11C]-raclopride positron emission tomography, in a sample of 24 healthy male individuals. Additional mediation and moderation effects with childhood trauma and key dopamine-regulating genes were examined. Results An inverse relationship between nondisplaceable binding potential and subclinical symptoms was identified. D2/3 receptor availability in the left putamen fully mediated the association between traumatic childhood experiences and odd beliefs, that is, inclinations to see meaning in randomness and unfounded interpretations. Moreover, the effect of early adversity was moderated by a DRD2 functional variant (rs1076560). The results link environmental and neurobiological influences in the striatum to the origination of psychosis spectrum symptomology, consistent with the social defeat and diathesis–stress models. Conclusions Adversity exposure may affect the dopamine system as in association with biases in probabilistic reasoning, attributional style, and salience processing. The inverse relationship between D2/3 availability and symptomology may be explained by endogenous dopamine occupying the receptor, postsynaptic compensatory mechanisms, and/or altered receptor sensitivity. This may also reflect a cognitively stabilizing mechanism in non-help-seeking individuals. Future research should comprehensively characterize molecular parameters of dopamine neurotransmission along the psychosis spectrum and according to subtype profiling. [ABSTRACT FROM AUTHOR]

Arousal may be understood on a spectrum, with excessive sleepiness, cognitive dysfunction, and inattention on one side, a wakeful state in the middle, and hypervigilance, panic, and psychosis on the other side. However, historically, the concepts of arousal and stress have been challenging to define as measurable experimental variables. Divergent efforts to study these subjects have given rise to several disciplines, including neurobiology, neuroendocrinology, and cognitive neuroscience. We discuss technological advancements that chronologically led to our current understanding of the arousal system, focusing on the multifaceted nucleus locus coeruleus. We share our contemporary perspective and the hypotheses of others in the context of our current technological capabilities and future developments that will be required to move forward in this area of research. [ABSTRACT FROM AUTHOR]

Volume-regulated anion channels (VRACs) encoded by the leucine-rich repeat containing 8 (LRRC8) gene family play critical roles in myriad cellular processes and might represent druggable targets. The dearth of pharmacological compounds available for studying VRAC physiology led us to perform a high-throughput screen of 1,184 of US Food and Drug Administration-approved drugs for novel VRAC modulators. We discovered the cysteinyl leukotriene receptor 1 (CysLT1R) antagonist, pranlukast, as a novel inhibitor of endogenous VRAC expressed in human embryonic kidney 293 (HEK293) cells. Pranlukast inhibits VRAC voltage-independently, reversibly, and dose-dependently with a maximal efficacy of only ~50%. The CysLT1R pathway has been implicated in activation of VRAC in other cell types, prompting us to test whether pranlukast requires the CysLT1R for inhibition of VRAC. Quantitative PCR analysis demonstrated that CYSLTR1 mRNA is virtually undetectable in HEK293 cells. Furthermore, the CysLT1R agonist leukotriene D4 had no effect on VRAC activity and failed to stimulate Gq-coupled receptor signaling. Heterologous expression of the CysLT1R reconstituted LTD4-CysLT1R- Gq-calcium signaling in HEK293 cells but had no effect on VRAC inhibition by pranlukast. Finally, we show the CysLT1R antagonist zafirlukast inhibits VRAC with an IC50 of ~17µM and does so with full efficacy. Our data suggest that both pranlukast and zafirlukast are likely direct channel inhibitors that work independently of the CysLT1R. This study provides clarifying insights into the putative role of leukotriene signaling in modulation of VRAC and identifies two new chemical scaffolds that can be used for development of more potent and specific VRAC inhibitors. [ABSTRACT FROM AUTHOR]

Spontaneous waves of cortical spreading depolarization (CSD) are induced in the setting of acute focal ischemia. CSD is linked to a sharp increase of extracellular K+ that induces a long-lasting suppression of neural activity. Furthermore, CSD induces secondary irreversible damage in the ischemic brain, suggesting that K+ homeostasis might constitute a therapeutic strategy in ischemic stroke. Here we report that adrenergic receptor (AdR) antagonism accelerates normalization of extracellular K+, resulting in faster recovery of neural activity after photothrombotic stroke. Remarkably, systemic adrenergic blockade before or after stroke facilitated functional motor recovery and reduced infarct volume, paralleling the preservation of the water channel aquaporin-4 in astrocytes. Our observations suggest that AdR blockers promote cerebrospinal fluid exchange and rapid extracellular K+ clearance, representing a potent potential intervention for acute stroke. [ABSTRACT FROM AUTHOR]

Glutamate is the most abundant neurotransmitter of the central nervous system, as the majority of neurons use glutamate as neurotransmitter. It is also well known that this neurotransmitter is not restricted to synaptic clefts, but found in the extrasynaptic regions as ambient glutamate. Extrasynaptic glutamate originates from spillover of synaptic release, as well as from astrocytes and microglia. Its concentration is magnitudes lower than in the synaptic cleft, but receptors responding to it have higher affinity for it. Extrasynaptic glutamate receptors can be found in neuronal somatodendritic location, on astroglia, oligodendrocytes or microglia. Activation of them leads to changes of neuronal excitability with different amplitude and kinetics. Extrasynaptic glutamate is taken up by neurons and astrocytes mostly via EAAT transporters, and astrocytes, in turn metabolize it to glutamine. Extrasynaptic glutamate is involved in several physiological phenomena of the central nervous system. It regulates neuronal excitability and synaptic strength by involving astroglia; contributing to learning and memory formation, neurosecretory and neuromodulatory mechanisms, as well as sleep homeostasis.The extrasynaptic glutamatergic system is affected in several brain pathologies related to excitotoxicity, neurodegeneration or neuroinflammation. Being present in dementias, neurodegenerative and neuropsychiatric diseases or tumor invasion in a seemingly uniform way, the system possibly provides a common component of their pathogenesis. Although parts of the system are extensively discussed by several recent reviews, in this review I attempt to summarize physiological actions of the extrasynaptic glutamate on neuronal excitability and provide a brief insight to its pathology for basic understanding of the topic. [ABSTRACT FROM AUTHOR]

How asymmetries in motor behavior become established normally or atypically in mammals remains unclear. An established model for motor asymmetry that is conserved across mammals can be obtained by experimentally inducing asymmetric striatal dopamine activity. However, the factors that can cause motor asymmetries in the absence of experimental manipulations to the brain remain unknown. Here, we show that mice with inner ear dysfunction display a robust left or right rotational preference, and this motor preference reflects an atypical asymmetry in cortico-striatal neurotransmission. By unilaterally targeting striatal activity with an antagonist of extracellular signal-regulated kinase (ERK), a downstream integrator of striatal neurotransmitter signaling, we can reverse or exaggerate rotational preference in these mice. By surgically biasing vestibular failure to one ear, we can dictate the direction of motor preference, illustrating the influence of uneven vestibular failure in establishing the outward asymmetries in motor preference. The inner ear–induced striatal asymmetries identified here intersect with non–ear-induced asymmetries previously linked to lateralized motor behavior across species and suggest that aspects of left–right brain function in mammals can be ontogenetically influenced by inner ear input. Consistent with inner ear input contributing to motor asymmetry, we also show that, in humans with normal ear function, the motor-dominant hemisphere, measured as handedness, is ipsilateral to the ear with weaker vestibular input. [ABSTRACT FROM AUTHOR]

In this Focused Review, we provide an update about evolving concepts that may link chronic stress and catecholamine autotoxicity with neurodegenerative diseases such as Parkinson's disease. Richard Kvetnansky's contributions to the field of stress and catecholamine systems inspired some of the ideas presented here. We propose that coordination of catecholaminergic systems mediates adjustments maintaining health and that senescence-related disintegration of these systems leads to disorders of regulation and to neurodegenerative diseases such as Parkinson's disease. Chronically repeated episodes of stress-related catecholamine release and reuptake, with attendant increases in formation of the toxic dopamine metabolite 3,4-dihydroxyphenylacetaldehyde, might accelerate this process. [ABSTRACT FROM AUTHOR]

Key points The volume-regulated anion channel (VRAC) is a swelling-activated chloride channel that is permeable to inorganic anions and a variety of small organic molecules., VRAC is formed via heteromerization of LRRC8 proteins, among which LRRC8A is essential, while LRRC8B/C/D/E serve as exchangeable complementary partners., We used an RNAi approach and radiotracer assays to explore which LRRC8 isoforms contribute to swelling-activated release of diverse organic osmolytes in rat astrocytes., Efflux of uncharged osmolytes ( myo-inositol and taurine) was suppressed by deletion of LRRC8A or LRRC8D, but not by deletion of LRRC8C+LRRC8E., Conversely, release of charged osmolytes ( d-aspartate) was strongly reduced by deletion of LRRC8A or LRRC8C+LRRC8E, but largely unaffected by downregulation of LRRC8D., Our findings point to the existence of multiple heteromeric VRACs in the same cell type: LRRC8A/D-containing heteromers appear to dominate release of uncharged osmolytes, while LRRC8A/C/E, with the additional contribution of LRRC8D, creates a conduit for movement of charged molecules., Abstract The volume-regulated anion channel (VRAC) is the ubiquitously expressed vertebrate Cl−/anion channel that is composed of proteins belonging to the LRRC8 family and activated by cell swelling. In the brain, VRAC contributes to physiological and pathological release of a variety of small organic molecules, including the amino acid neurotransmitters glutamate, aspartate and taurine. In the present work, we explored the role of all five LRRC8 family members in the release of organic osmolytes from primary rat astrocytes. Expression of LRRC8 proteins was modified using an RNAi approach, and amino acid fluxes via VRAC were quantified by radiotracer assays in cells challenged with hypoosmotic medium (30% reduction in osmolarity). Consistent with our prior work, knockdown of LRRC8A potently and equally suppressed the release of radiolabelled d-[14C]aspartate and [3H]taurine. Among other LRRC8 subunits, downregulation of LRRC8D strongly inhibited release of the uncharged osmolytes [3H]taurine and myo-[3H]inositol, without major impact on the simultaneously measured efflux of the charged d-[14C]aspartate. In contrast, the release of d-[14C]aspartate was preferentially sensitive to deletion of LRRC8C+LRRC8E, but unaffected by downregulation of LRRC8D. Finally, siRNA knockdown of LRRC8C+LRRC8D strongly inhibited the release of all osmolytes. Overall, our findings suggest the existence of at least two distinct heteromeric VRACs in astroglial cells. The LRRC8A/D-containing permeability pathway appears to dominate the release of uncharged osmolytes, while an alternative channel (or channels) is composed of LRRC8A/C/D/E and responsible for the loss of charged molecules. [ABSTRACT FROM AUTHOR]

A major theme of addiction research has focused on the neural substrates of individual differences in the risk for addiction; however, little is known about how vulnerable populations differ from those that are relatively protected. Here, we prospectively measured dopamine (DA) neurotransmission prior to cocaine exposure to predict the onset and course of cocaine use. Using in vivo voltammetry, we first generated baseline profiles of DA release and uptake in the dorsomedial striatum (DMS) and nucleus accumbens of drug-naïve male rats prior to exposing them to cocaine using conditioned place preference (CPP) or operant self-administration. We found that the innate rate of DA uptake in the DMS strongly predicted motivation for cocaine and drug-primed reinstatement, but not CPP, responding when "price" was low, or extinction. We then assessed the impact of baseline variations in DA uptake on cocaine potency in the DMS using ex vivo voltammetry in naïve rats and in rats with DA transporter (DAT) knockdown. DA uptake in the DMS of naïve rats predicted the neurochemical response to cocaine, such that rats with innately faster rates of DA uptake demonstrated higher cocaine potency at the DAT and rats with DAT knockdown displayed reduced potency compared to controls. Together, these data demonstrate that inherent variability in DA uptake in the DMS predicts the behavioral response to cocaine, potentially by altering the apparent potency of cocaine., (© 2021. The Author(s), under exclusive licence to American College of Neuropsychopharmacology.)

The immune privileged nature of the CNS can make it vulnerable to chronic and latent infections. Little is known about the effects of lifelong brain infections, and thus inflammation, on the neurological health of the host. Toxoplasma gondii is a parasite that can infect any mammalian nucleated cell with average worldwide seroprevalence rates of 30%. Infection by Toxoplasma is characterized by the lifelong presence of parasitic cysts within neurons in the brain, requiring a competent immune system to prevent parasite reactivation and encephalitis. In the immunocompetent individual, Toxoplasma infection is largely asymptomatic, however many recent studies suggest a strong correlation with certain neurodegenerative and psychiatric disorders. Here, we demonstrate a significant reduction in the primary astrocytic glutamate transporter, GLT-1, following infection with Toxoplasma. Using microdialysis of the murine frontal cortex over the course of infection, a significant increase in extracellular concentrations of glutamate is observed. Consistent with glutamate dysregulation, analysis of neurons reveal changes in morphology including a reduction in dendritic spines, VGlut1 and NeuN immunoreactivity. Furthermore, behavioral testing and EEG recordings point to significant changes in neuronal output. Finally, these changes in neuronal connectivity are dependent on infection-induced downregulation of GLT-1 as treatment with the ß-lactam antibiotic ceftriaxone, rescues extracellular glutamate concentrations, neuronal pathology and function. Altogether, these data demonstrate that following an infection with T. gondii, the delicate regulation of glutamate by astrocytes is disrupted and accounts for a range of deficits observed in chronic infection. [ABSTRACT FROM AUTHOR]

Background and Purpose: Substance P and its preferred neurokinin receptor NK1 have been implicated in stress and anxiety and have been proposed as possible therapeutic targets for the treatment of anxiety/depression. Attention is also being focused on the role this neuropeptide system may play in drug addiction, because stress-related mechanisms promote drug abuse.Experimental Approach: The effects of the rat-specific NK1 receptor antagonist, L822429, on alcohol intake and seeking behaviour was investigated in genetically selected Marchigian Sardinian alcohol preferring rats. These rats demonstrate an anxious phenotype and are highly sensitive to stress and stress-induced drinking.Key Results: Systemic administration of L822429 significantly reduced operant alcohol self-administration in Marchigian Sardinian alcohol preferring rats, but did not reduce alcohol self-administration in stock Wistar rats. NK1 receptor antagonism also attenuated yohimbine-induced reinstatement of alcohol seeking at all doses tested but had no effect on cue-induced reinstatement of alcohol seeking. L822429 reduced operant alcohol self-administration when injected into the lateral cerebroventricles or the medial amygdala. L822429 injected into the medial amygdala also significantly reduced anxiety-like behaviour in the elevated plus maze test. No effects on alcohol intake were observed following injection of L822429 into the dorsal or the ventral hippocampus. Conclusions and Implications Our results suggest that NK1 receptor antagonists may be useful for the treatment of alcohol addiction associated with stress or comorbid anxiety disorders. The medial amygdala appears to be an important brain site of action of NK1 receptor antagonism. [ABSTRACT FROM AUTHOR]

Background: Methylphenidate (MPH) is a commonly-used medication for the treatment of children with Attention-Deficit/Hyperactivity Disorders (ADHD). However, its prescription to adults with ADHD and narcolepsy raises the question of how the brain is impacted by MPH exposure during pregnancy. The goal of this study was to elucidate the long-term neurobiological consequences of prenatal exposure to MPH using a rat model. Methods: We focused on the effects of such treatment on the adult dopamine (DA) system and on the reactivity of animals to natural rewards. Results: This study shows that adult male rats prenatally exposed to MPH display elevated expression of presynaptic DA markers in the DA cell bodies and the striatum. Our results also suggest that MPH-treated animals could exhibit increased tonic DA activity in the mesolimbic pathway, altered signal-to-noise ratio after a pharmacological stimulation, and decreased reactivity to the locomotor effects of cocaine. Finally, we demonstrated that MPH rats display a decreased preference and motivation for sucrose. Conclusions: This is the first preclinical study reporting long-lasting neurobiological alterations of DA networks as well as alterations in motivational behaviors for natural rewards after a prenatal exposure to MPH. These results raise concerns about the possible neurobiological consequences of MPH treatment during pregnancy. [ABSTRACT FROM AUTHOR]

Background: Methylphenidate (MPH) is a commonly-used medication for the treatment of children with Attention-Deficit/Hyperactivity Disorders (ADHD). However, its prescription to adults with ADHD and narcolepsy raises the question of how the brain is impacted by MPH exposure during pregnancy. The goal of this study was to elucidate the long-term neurobiological consequences of prenatal exposure to MPH using a rat model. Methods: We focused on the effects of such treatment on the adult dopamine (DA) system and on the reactivity of animals to natural rewards. Results: This study shows that adult male rats prenatally exposed to MPH display elevated expression of presynaptic DA markers in the DA cell bodies and the striatum. Our results also suggest that MPH-treated animals could exhibit increased tonic DA activity in the mesolimbic pathway, altered signal-to-noise ratio after a pharmacological stimulation, and decreased reactivity to the locomotor effects of cocaine. Finally, we demonstrated that MPH rats display a decreased preference and motivation for sucrose. Conclusions: This is the first preclinical study reporting long-lasting neurobiological alterations of DA networks as well as alterations in motivational behaviors for natural rewards after a prenatal exposure to MPH. These results raise concerns about the possible neurobiological consequences of MPH treatment during pregnancy. [ABSTRACT FROM AUTHOR]

In mammals, cellular swelling activates release of small organic osmolytes, including the excitatory amino acids (EAA) glutamate and aspartate, via a ubiquitously expressed volume-regulated chloride/anion channel (VRAC). Pharmacological evidence suggests that VRAC plays plural physiological and pathological roles, including excitotoxic release of glutamate in stroke. However, the molecular identity of this pathway was unknown. Two recent studies discovered that LRRC8 gene family members encode heteromeric VRAC composed of LRRC8A plus LRRC8B-E, which mediate swelling-activated Cl- currents and taurine release in human non-neural cells (Z. Qiu et al. Cell 157: 447, 2014; F.K. Voss et al. Science 344: 634, 2014). Here, we tested the contribution of LRRC8A to the EAA release in brain glia. We detected and quantified expression levels of LRRC8A-E in primary rat astrocytes with quantitative RT-PCR and then downregulated LRRC8A with gene-specific siRNAs. In astrocytes exposed to hypo-osmotic media, LRRC8A knockdown dramatically reduced swelling-activated release of the EAAtracer D-[³H]aspartate. In parallelHPLCassays, LRRC8AsiRNAprevented hypo-osmotic media-induced loss of the endogenous intracellular L-glutamate and taurine. Furthermore, downregulation of LRRC8A completely ablated the ATP-stimulated release of D-[³H]aspartate and [14C]taurine from non-swollen astrocytes. Overall, these data indicate that LRRC8A is an indispensable component of a permeability pathway that mediates both swelling-activated and agonist-induced amino acid release in brain glial cells. [ABSTRACT FROM AUTHOR]

Neurons in the brainstem nucleus locus ceruleus (LC) often exhibit phasic activation in the context of simple sensory-motor tasks. The functional role of this activation, which leads to the release of norepinephrine throughout the brain, is not yet understood in part because the conditions under which it occurs remain in question. Early studies focused on the relationship of LC phasic activation to salient sensory events, whereas more recent work has emphasized its timing relative to goal-directed behavioral responses, possibly representing the end of a sensory-motor decision process. To better understand the relationship between LC phasic activation and sensory, motor, and decision processing, we recorded spiking activity of neurons in the LC+ (LC and the adjacent, norepinephrine-containing subceruleus nucleus) of monkeys performing a countermanding task. The task required the monkeys to occasionally withhold planned, saccadic eye movements to a visual target. We found that many well isolated LC+ units responded to both the onset of the visual cue instructing the monkey to initiate the saccade and again after saccade onset, even when it was initiated erroneously in the presence of a stop signal. Many of these neurons did not respond to saccades made outside of the task context. In contrast, neither the appearance of the stop signal nor the successful withholding of the saccade elicited an LC+ response. Therefore, LC+ phasic activation encodes sensory and motor events related to decisions to execute, but not withhold, movements, implying a functional role in goal-directed actions, but not necessarily more covert forms of processing. [ABSTRACT FROM AUTHOR]

Since its discovery, the nociceptin/orphanin FQ (N/OFQ)-NOP receptor system has been extensively investigated as a promising target to treat alcoholism. Encouraging results obtained with the endogenous ligand N/OFQ stimulated research towards the development of novel brain-penetrating NOP receptor agonists with a pharmacological and toxicological profile compatible with clinical development. Here we describe the biochemical and alcohol-related behavioral effects of the novel NOP receptor agonist MT-7716. MT-7716 has high affinity for human NOP receptors expressed in HEK293 cells with a Ki value of 0.21 nM. MT-7716 concentration-dependently stimulated GTPγ35S binding with an EC50 value of 0.30 nM and its efficacy was similar to N/OFQ, suggesting that MT7716 is a full agonist at NOP receptors. In the two bottle choice test MT-7716 (0, 0.3, 1, and 3 mg/kg, bid) given orally for 14 days dose-dependently decreased voluntary alcohol intake in Marchigian Sardinian rats. The effect became gradually stronger following repeated administration, and was still significant 1 week after discontinuation of the drug. Oral naltrexone (30 mg/kg, bid) for 14 days also reduced ethanol intake; however, the effect decreased over the treatment period and rapidly disappeared when drug treatment was discontinued. MT-7716 is also effective for preventing reinstatement caused by both ethanol-associated environmental stimuli and stress. Finally, to investigate the effect of MT-7716 on alcohol withdrawal symptoms, Wistar rats were withdrawn from a 7-day alcohol liquid diet. MT-7716 significantly attenuated somatic alcohol withdrawal symptoms. Together these findings indicate that MT-7716 is a promising candidate for alcoholism treatment remaining effective with chronic administration. [ABSTRACT FROM AUTHOR]

Our previous study has shown that cerebral ischemic preconditioning (CIP) can up-regulate the expression of glial glutamate transporter-1 (GLT-1) during the induction of brain ischemic tolerance in rats. The present study was undertaken to further explore the uptake activity of GLT-1 in the process by observing the changes in the concentration of extracellular glutamate with cerebral microdialysis and high-performance liquid chromatography. The results showed that a significant pulse of glutamate concentration reached the peak value of sevenfold of the basal level after lethal ischemic insult, which was associated with delayed neuronal death in the CA1 hippocampus. When the rats were pretreated 2 days before the lethal ischemic insult with CIP which protected the pyramidal neurons against delayed neuronal death, the peak value of glutamate concentration decreased to 3.9 fold of the basal level. Furthermore, pre-administration of dihydrokainate, an inhibitor of GLT-1, prevented the protective effect of CIP on ischemia-induced CA1 cell death. At the same time, compared with the CIP + Ischemia group, the peak value of glutamate concentration significantly increased and reached sixfold of the basal level. These results indicate that CIP induced brain ischemic tolerance via up-regulating GLT-1 uptake activity for glutamate and then decreasing the excitotoxicity of glutamate. [ABSTRACT FROM AUTHOR]

Pupillary measures have been linked to arousal and attention as well as activity in the brainstem's locus coeruleus norepinephrine (LC-NE) system. Similarly, there is evidence that evoked EEG responses, such as the P3, might have LC-NE activity as their basis. Since it is not feasible to record electrophysiological data directly from the LC in humans due to its location in the brainstem, an open question has been whether pupillary measures and EEG variability can be linked in a meaningful way to shed light on the nature of the LC-NE role in attention and arousal. We used an auditory oddball task with a data-driven approach to learn task-relevant projections of the EEG, for windows of data spanning the entire trial. We investigated linear and quadratic relationships between the evoked EEG along these projections and both prestimulus (baseline) and poststimulus (evoked dilation) pupil diameter measurements. We found that baseline pupil diameter correlates with early (175–200 ms) and late (350–400 ms) EEG component variability, suggesting a linear relationship between baseline (tonic) LC-NE activity and evoked EEG. We found no relationships between evoked EEG and evoked pupil dilation, which is often associated with evoked (phasic) LC activity. After regressing out reaction time (RT), the correlation between EEG variability and baseline pupil diameter remained, suggesting that such correlation is not explainable by RT variability. We also investigated the relationship between these pupil measures and prestimulus EEG alpha activity, which has been reported as a marker of attentional state, and found a negative linear relationship with evoked pupil dilation. In summary, our results demonstrate significant relationships between prestimulus and poststimulus neural and pupillary measures, and they provide further evidence for tight coupling between attentional state and evoked neural activity and for the role of cortical and subcortical networks underlying the process of target detection. [ABSTRACT FROM AUTHOR]

Background Using senescence-accelerated mouse prone 8 (SAMP8), we examined whether reduced mastication from a young age affects hippocampal-dependent cognitive function. We anesthetized male SAMP8 mice at 8 weeks of age and extracted all maxillary molar teeth of half the animals. The other animals were treated similarly, except that molar teeth were not extracted. At 12 and 24 weeks of age, their general behavior and their ability to recognize novel objects were tested using the open-field test (OFT) and the object-recognition test (ORT), respectively. Results The body weight of molarless mice was reduced significantly compared to that of molarintact mice after the extraction and did not recover to the weight of age-matched molar-intact mice throughout the experimental period. At 12 weeks of age, molarless mice showed significantly greater locomotor activity in the OFT than molar-intact mice. However, the ability of molarless mice to discriminate a novel object in the ORT was impaired compared to that of molar-intact mice. The ability of both molarless and molar-intact SAMP8 mice to recognize objects was impaired at 24 weeks of age. These results suggest that molarless SAMP8 mice develop a deficit of cognitive function earlier than molar-intact SAMP8 mice. Interestingly, both at 12 and 24 weeks of age, molarless mice showed a lateralized preference of object location in the encoding session of the ORT, in which two identical objects were presented. Their lateralized preference of object location was positively correlated with the rightward turning-direction preference, which reached statistical significance at 24 weeks of age. Conclusions Loss of masticatory function in early life causes malnutrition and chronic stress and impairs the ability to recognize novel objects. Hyperactivation and lateralized rotational behavior are commonly observed with dysfunction of the dopaminergic system, therefore, reduced masticatory function may deplete the mesolimbic and mesocorticolimbic dopaminergic systems to impair the cognitive functions of selective attention and recognition memory in the prefrontal cortex and the hippocampus. [ABSTRACT FROM AUTHOR]

Methamphetamine (METH) is a widely abused amphetamine analog. Few studies have investigated the molecular effects of METH exposure in adult animals. Herein, we determined the consequences of an injection of METH (10 mg/kg) on transcriptional effects of a second METH (2.5 mg/kg) injection given one month later. We thus measured gene expression by microarray analyses in the nucleus accumbens (NAc) of 4 groups of rats euthanized 2 hours after the second injection: saline-pretreated followed by saline-challenged (SS) or METH-challenged (SM); and METH-pretreated followed by saline-challenged (MS) or METH-challenged (MM). Microarray analyses revealed that METH (2.5 mg/kg) produced acute changes (1.8-fold; P<0.01) in the expression of 412 (352 upregulated, 60 down-regulated) transcripts including cocaine and amphetamine regulated transcript, corticotropin-releasing hormone (Crh), oxytocin (Oxt), and vasopressin (Avp) that were upregulated. Injection of METH (10 mg/kg) altered the expression of 503 (338 upregulated, 165 down-regulated) transcripts measured one month later (MS group). These genes also included Cart and Crh. The MM group showed altered expression of 766 (565 upregulated, 201 down-regulated) transcripts including Avp, Cart, and Crh. The METH-induced increased Crh expression was enhanced in the MM group in comparison to SM and MS groups. Quantitative PCR confirmed the METH-induced changes in mRNA levels. Therefore, a single injection of METH produced long-lasting changes in gene expression in the rodent NAc. The long-term increases in Crh, Cart, and Avp mRNA expression suggest that METH exposure produced prolonged activation of the endogenous stress system. The METH-induced changes in oxytocin expression also suggest the possibility that this neuropeptide might play a significant role in the neuroplastic and affiliative effects of this drug. [ABSTRACT FROM AUTHOR]

Hypoxia ischemia (HI)-related brain injury is the major cause of long-term morbidity in neonates. One characteristic hallmark of neonatal HI is the development of reactive astrogliosis in the hippocampus. However, the impact of reactive astrogliosis in hippocampal damage after neonatal HI is not fully understood. In the current study, we investigated the role of Na+/H+ exchanger isoform 1 (NHE1) protein in mouse reactive hippocampal astrocyte function in an in vitro ischemia model (oxygen/glucose deprivation and reoxygenation, OGD/REOX). 2 h OGD significantly increased NHE1 protein expression and NHE1-mediated H+ efflux in hippocampal astrocytes. NHE1 activity remained stimulated during 1–5 h REOX and returned to the basal level at 24 h REOX. NHE1 activation in hippocampal astrocytes resulted in intracellular Na+ and Ca2+ overload. The latter was mediated by reversal of Na+/Ca2+ exchange. Hippocampal astrocytes also exhibited a robust release of gliotransmitters (glutamate and pro-inflammatory cytokines IL-6 and TNFα) during 1–24 h REOX. Interestingly, inhibition of NHE1 activity with its potent inhibitor HOE 642 not only reduced Na+ overload but also gliotransmitter release from hippocampal astrocytes. The noncompetitive excitatory amino acid transporter inhibitor TBOA showed a similar effect on blocking the glutamate release. Taken together, we concluded that NHE1 plays an essential role in maintaining H+ homeostasis in hippocampal astrocytes. Over-stimulation of NHE1 activity following in vitro ischemia disrupts Na+ and Ca2+ homeostasis, which reduces Na+-dependent glutamate uptake and promotes release of glutamate and cytokines from reactive astrocytes. Therefore, blocking sustained NHE1 activation in reactive astrocytes may provide neuroprotection following HI. [ABSTRACT FROM AUTHOR]

Key points The medial prefrontal cortex (mPFC) is often referred to as the 'visceral cortex', largely based on anatomical connections and cardiovascular influences., Although an extensive network of inhibitory interneurons regulates PFC function, their roles in modifying central respiratory, metabolic and cardiac functions have not been explored., This study provides the first integrative investigation describing central respiratory, metabolic and cardiac variables altered following chemical disinhibition of discrete subregions of the mPFC., Changes were evoked in a site-dependent manner, with central respiratory function modified throughout the mPFC, and exclusively from dorsal regions. By contrast, central respiratory, metabolic and cardiac functions were simultaneously increased in the ventral mPFC, particularly the infralimbic cortex., These data provide reference material for future investigations into chronic changes in the activity of neurons within the mPFC, as seen in stress and mental health disorders, which are often accompanied by autonomic and respiratory dysfunction., Abstract The prefrontal cortex (PFC) is referred to as the visceral motor cortex; however, little is known about whether this region influences respiratory or metabolic outflows. The aim of this study was to describe simultaneous changes in respiratory, metabolic and cardiovascular functions evoked by disinhibition of the medial PFC (mPFC) and adjacent lateral septal nucleus (LSN). In urethane-anaesthetized rats, bicuculline methiodide was microinjected (2 m m; GABA-A receptor antagonist) into 90 sites in the mPFC at 0.72-4.00 mm from bregma. Phrenic nerve amplitude and frequency, arterial pressure, heart rate, splanchnic and lumbar sympathetic nerve activities (SNA), expired CO2, and core and brown adipose tissue temperatures were measured. Novel findings included disturbances to respiratory rhythm evoked from all subregions of the mPFC. Injections into the cingulate cortex evoked reductions in central respiratory function exclusively, whereas in ventral sites, particularly the infralimbic region, increases in respiratory drive and frequency, and metabolic and cardiac outflows were evoked. Disinhibition of sites in surrounding regions revealed that the LSN could evoke cardiovascular changes accompanied by distinct oscillations in SNA, as well as increases in respiratory amplitude. We show that activation of neurons within the mPFC and LSN influence respiratory, metabolic and cardiac outflows in a site-dependent manner. This study has implications with respect to the altered PFC neuronal activity seen in stress-related and mental health disorders, and suggests how basic physiological systems may be affected. [ABSTRACT FROM AUTHOR]

Aims Anesthesia is related to cognitive impairment and the risk for Alzheimer's disease. Hypothermia during anesthesia can lead to abnormal hyperphosphorylation of tau, which has been speculated to be involved in anesthesia-induced cognitive impairment. The aim of this study was to investigate whether maintenance of the tau phosphorylation level by body temperature control during anesthesia could reverse the cognitive dysfunction in C57BL/6 mice. Methods Eighteen-month-old mice were repeatedly anesthetized during a 2-week period with or without maintenance of body temperature, control mice were treated with normal saline instead of anesthetics. Tau phosphorylation level in mice brain was detected on western blot, and cognitive performance was measured using the Morris water maze ( MWM). Results After anesthesia-induced hypothermia in old mice, tau was hyperphosphorylated and the cognitive performance, measured on MWM, was impaired. When body temperature was controlled during anesthesia, however, the tau hyperphosphorylation was completely avoided, and there was partial recovery in cognitive impairment measured on the MWM. Conclusion Hyperphosphorylation of tau in the brain after anesthesia is an important event, and it might be, although not solely, responsible for postoperative cognitive decline. [ABSTRACT FROM AUTHOR]

A fast microchip electrophoresis-nano-electrospray ionization-mass spectrometric method (MCE-nanoESI-MS) was developed for analysis of amino acids in biological samples. A glass/poly(dimethylsiloxane) hybrid microchip with a monolithic nanoESI emitter was used in the platform. The proposed MCE-nanoESI-MS analytical method showed high separation efficiency for amino acids. Baseline separation of an amino acid mixture containing Lys, Arg, Val, Tyr, and Glu was completed within 120 s with theoretical plate numbers of >7,500. The method was applied to study cellular release of excitatory amino acids (i.e., aspartic acid (Asp) and glutamic acid (Glu)) under chemical stimulations. Linear calibration curves were obtained for both Asp and Glu in a concentration range from 1.00 to 150.0 μM. Limits of detection were found to be 0.37 μM for Asp and 0.33 μM for Glu ( S/ N = 3). Assay repeatability (relative standard deviation, n = 6) was 4.2 and 4.5 %, for Asp and Glu at 5.0 μM, respectively. In the study of cellular release, PC-12 nerve cells were incubated with alcohol at various concentrations for 1 h. Both extra- and intracellular levels of Asp and Glu were measured by the proposed method. The results clearly indicated that ethanol promoted the release of both Asp and Glu from the cells. [ABSTRACT FROM AUTHOR]

Translational approaches to study the neural substrates of stress and assess the mechanistic efficacy of novel anti-anxiety agents necessitate the use of stressors with a similar degree of saliency across species. The alpha-2 adrenoreceptor antagonist yohimbine represents an attractive experimental tool owing to its well-documented stress-inducing properties in humans and laboratory species. We investigated the neural substrates engaged by yohimbine in the rat brain by using functional magnetic resonance imaging and mapped their modulation by neurotransmitter systems involved in stress responses. Yohimbine elicited a composite pattern of brain activation, highlighting the recruitment of cortico-striato-thalamic regions and extra-hypothalamic stress neurocircuits. This effect was strongly attenuated by the α-2-adrenoceptor agonist medetomidine and by the dopamine (DA) D1 receptor antagonist SCH23390, thus revealing a primary contribution of both norepinephrine and DA on the neurofunctional cascade elicited by the drug. Pretreatment with the corticotrophin-releasing factor type-1 receptor (CRF1R) antagonist CP154,526 produced a region-dependent inhibition of yohimbine-induced activation in the amygdala, striatum, and cingulate cortex, while the orexin type-1 receptor (OX1R) antagonists GSK1059865 robustly inhibited the response in fronto-hippocampal regions as well as in several key components of the extended amygdala. CP154,526 and GSK1059865 did not prevent yohimbine-induced plasma corticosterone release, a finding that corroborates a central origin of the effects mapped. Our findings provide novel insight into the brain substrates and neurochemical mediators engaged by the stress-inducing agent yohimbine. The differential pattern of inhibition produced by CRF1R and OX1R antagonists suggests that these two neuropeptide systems can modulate the functional response to stress via distinct central neural pathways. [ABSTRACT FROM AUTHOR]

Astrocytes, a major class of glial cells, regulate neurotransmitter systems, synaptic processing, ion homeostasis, antioxidant defenses and energy metabolism. Astrocyte cultures derived from rodent brains have been extensively used to characterize astrocytes' biochemical, pharmacological and morphological properties. The aims of this study were to develop a protocol for routine preparation and to characterize a primary astrocyte culture from the brains of adult (90 days old) Wistar rats. For this we used enzymatic digestion (trypsin and papain) and mechanical dissociation. Medium exchange occurred from 24 h after obtaining a culture and after, twice a week up to reach the confluence (around the 4th to 5th week). Under basal conditions, adult astrocytes presented a polygonal to fusiform and flat morphology. Furthermore, approximately 95% the cells were positive for the main glial markers, including GFAP, glutamate transporters, glutamine synthetase and S100B. Moreover, the astrocytes were able to take up glucose and glutamate. Adult astrocytes were also able to respond to acute H2O2 exposure, which led to an increase in reactive oxygen species (ROS) levels and a decrease in glutamate uptake. The antioxidant compound resveratrol was able to protect adult astrocytes from oxidative damage. A response of adult astrocytes to an inflammatory stimulus with LPS was also observed. Changes in the actin cytoskeleton were induced in stimulated astrocytes, most likely by a mechanism dependent on MAPK and Rho A signaling pathways. Taken together, these findings indicate that the culture model described in this study exhibits the biochemical and physiological properties of astrocytes and may be useful for elucidating the mechanisms related to the adult brain, exploring changes between neonatal and adult astrocytes, as well as investigating compounds involved in cytotoxicity and cytoprotection. [ABSTRACT FROM AUTHOR]

Copyright of Neuroscience Bulletin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Neuroscience Bulletin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A role for dopamine (DA) release in the hallucinations and other positive symptoms associated with schizophrenia has long been inferred from the antipsychotic response to D2 DA receptor antagonists and because the DA releaser amphetamine can be psychotogenic. Recent studies suggest that patients with schizophrenia, including those never exposed to antipsychotic drugs, maintain high presynaptic DA accumulation in the striatum. New laboratory approaches are elucidating mechanisms that control the level of presynaptic DA stores, thus contributing to fundamental understanding of the basic pathophysiologic mechanism in schizophrenia. [ABSTRACT FROM PUBLISHER]

Investigations on the anodic decomposition of urea using Ti/Pt and Ti/(RuO2–TiO2)40:60 electrodes were carried out. The kinetics of the process were examined in a periodic electrolyser. The effect of anodic current density, initial urea concentration, and sodium chloride concentration on the effectiveness of the basic process (average rate of urea decomposition, current efficiency, and unit power consumption) is discussed. When a Ti/Pt electrode is applied for urea removal from aqueous solution urea is not decomposed directly at the surface of the electrode, but rather in the bulk of the solution by hypochlorite formed during the process. When the Ti/(RuO2–TiO2)40:60 electrode is used for the removal of urea from aqueous solutions, the reaction of urea with chlorine adsorbed at the electrode predominates. In both cases non-toxic products of urea decomposition (N2, CO2,) are formed. Comparison of the effectiveness of anodic decomposition of urea for the Ti/Pt and Ti/(RuO2–TiO2)40:60 electrodes in the periodic electrolyser at optimum process parameters has revealed that the former electrode is more favorable. [ABSTRACT FROM AUTHOR]

This observational microdialysis (MD) study of 33 subarachnoid hemorrhage patients explores brain interstitial levels of glutamine, glutamate, lactate and pyruvate, and their relationship to clinical status and clinical course at the neurointensive care unit. The focus was on ischemic events, defined by clinical criteria or by radiology, and the significance of brain interstitial glutamine levels and lactate/pyruvate (L/P) ratio. Eleven out of 12 periods with an ischemic MD pattern, defined as lactate/pyruvate (L/P) ratios exceeding 40, were either related to delayed ischemic neurological deficits (DIND) or CT-verified infarcts, confirming that L/P above 40 is a specific ischemic and pathological MD measure. Poor admittance WFNS grade (WFNS 4–5) patients had lower glutamine at the onset of monitoring than what good admittance WFNS grade (WFNS 1–3) patients had ( P < 0.05). Interstitial glutamine increased over time in most patients. A “glutamine surge” was defined as a period where the interstitial glutamine concentration increased at least 150 μM over 12 h. Fifteen patients had a DIND and associated MD patterns were glutamine surges (n = 12) and/or L/P>40 (n = 6). Seven patients received vasospasm treatment; in five of these the only DIND-associated MD pattern was a glutamine surge. Seventy percent of the glutamine surges occurred during ongoing propofol sedation, and there was no association between extubations and glutamine surges. There was no difference in mean glutamine levels during the monitoring period between patients with favorable 6-month outcome and patients with poor 6-month outcome. We suggest that an increasing interstitial glutamine trend is a dynamic sign of augmented astrocytic metabolism with accelerated glutamate uptake and glutamine synthesis. This pattern is presumably present in metabolically challenged, but yet not overt ischemic tissue. [ABSTRACT FROM AUTHOR]

A variety of physiological and pathological factors induce cellular swelling in the brain. Changes in cell volume activate several types of ion channels, which mediate the release of inorganic and organic osmolytes and allow for compensatory cell volume decrease. Volume-regulated anion channels (VRAC) are thought to be responsible for the release of some of organic osmolytes, including the excitatory neurotransmitters glutamate and aspartate. In the present study, we compared the in vivo properties of the swelling-activated release of glutamate, aspartate, and another major brain osmolyte taurine. Cell swelling was induced by perfusion of hypoosmotic (low [NaCl]) medium via a microdialysis probe placed in the rat cortex. The hypoosmotic medium produced several-fold increases in the extracellular levels of glutamate, aspartate and taurine. However, the release of the excitatory amino acids differed from the release of taurine in several respects including: (i) kinetic properties, (ii) sensitivity to isoosmotic changes in [NaCl], and (iii) sensitivity to hydrogen peroxide, which is known to modulate VRAC. Consistent with the involvement of VRAC, hypoosmotic medium-induced release of the excitatory amino acids was inhibited by the anion channel blocker DNDS, but not by the glutamate transporter inhibitor TBOA or Cd2+, which inhibits exocytosis. In order to elucidate the mechanisms contributing to taurine release, we studied its release properties in cultured astrocytes and cortical synaptosomes. Similarities between the results obtained in vivo and in synaptosomes suggest that the swelling-activated release of taurine in vivo may be of neuronal origin. Taken together, our findings indicate that different transport mechanisms and/or distinct cellular sources mediate hypoosmotic medium-induced release of the excitatory amino acids and taurine in vivo. [ABSTRACT FROM AUTHOR]

Previous studies documented significant behavioral changes in the offspring of cocaine-exposed mothers. We now explore the hypothesis that maternal cocaine exposure could alter the fetal epigenetic machinery sufficiently to cause lasting neurochemical and functional changes in the offspring. Pregnant CD1 mice were administered either saline or 20 mg/kg cocaine twice daily on gestational days 8-19. Male pups from each of ten litters of the cocaine and control groups were analyzed at 3 (P3) or 30 (P30) days postnatum. Global DNA methylation, methylated DNA immunoprecipitation followed by CGI2 microarray profiling and bisulfite sequencing, as well as quantitative real-time RT-PCR gene expression analysis, were evaluated in hippocampal pyramidal neurons excised by laser capture microdissection. Following maternal cocaine exposure, global DNA methylation was significantly decreased at P3 and increased at P30. Among the 492 CGIs whose methylation was significantly altered by cocaine at P3, 34% were hypermethylated while 66% were hypomethylated. Several of these CGIs contained promoter regions for genes implicated in crucial cellular functions. Endogenous expression of selected genes linked to the abnormally methylated CGIs was correspondingly decreased or increased by as much as 4-19- fold. By P30, some of the cocaine-associated effects at P3 endured, reversed to opposite directions, or disappeared. Further, additional sets of abnormally methylated targets emerged at P30 that were not observed at P3. Taken together, these observations indicate that maternal cocaine exposure during the second and third trimesters of gestation could produce potentially profound structural and functional modifications in the epigenomic programs of neonatal and prepubertal mice. [ABSTRACT FROM AUTHOR]

Ubiquitously expressed volume-regulated anion channels (VRACs) are chloride channels which are permeable to a variety of small organic anions, including the excitatory amino acids (EAAs) glutamate and aspartate. Broad spectrum anion channel blockers strongly reduce EAA release in cerebral ischaemia and other pathological states associated with prominent astrocytic swelling. However, it is uncertain whether VRAC serves as a major pathway for EAA release from swollen cells. In the present study, we measured swelling-activated release of EAAs asd-[3H]aspartate efflux, and VRAC-mediated Cl− currents by whole-cell patch clamp in cultured rat astrocytes. We compared the pharmacological profiles of the swelling-activated EAA release pathway and Cl− currents. The expression of candidate Cl− channels was confirmed by RT-PCR. The maxi Cl− channel (p-VDAC) blocker Gd3+, the ClC-2 inhibitor Cd2+, and the MDR-1 blocker verapamil did not affect EAA release or VRAC currents. An antagonist of calcium-sensitive Cl− channels (CaCC), niflumic acid, had little effect on EAA release and only partially inhibited swelling-activated Cl− currents. The phorbol ester PDBu, which blocks ClC-3-mediated Cl− currents, had no effect on VRAC currents and up-regulated EAA release. In contrast, DCPIB, which selectively inhibits VRACs, potently suppressed both EAA release and VRAC currents. Two other relatively selective VRAC inhibitors, tamoxifen and phloretin, also blocked the VRAC currents and strongly reduced EAA release. Taken together, our data suggest that (i) astrocytic volume-dependent EAA release is largely mediated by the VRAC, and (ii) the ClC-2, ClC-3, ClC-4, ClC-5, VDAC, CaCC, MDR-1 and CFTR gene products do not contribute to EAA permeability. [ABSTRACT FROM AUTHOR]

Ubiquitously expressed volume-regulated anion channels (VRACs) are activated in response to cell swelling but may also show limited activity in nonswollen cells. VRACs are permeable to inorganic anions and small organic osmolytes, including the amino acids aspartate, glutamate, and taurine. Several recent reports have demonstrated that neurotransmitters or hormones, such as ATP and vasopressin, induce or strongly potentiate astrocytic whole cell Cl- currents and amino acid release, which are inhibited by VRAC blockers. In the present study, we explored the intracellular signaling mechanisms mediating the effects of ATP on D-[3H]aspartate release via the putative VRAC pathway in rat primary astrocyte cultures. Cells were exposed to moderate (5%) or substantial (30%) reductions in medium osmolarity. ATP strongly potentiated D-[3H]aspartate release in both moderately swollen and substantially swollen cells. These ATP effects were blocked (≥80% inhibition) by intracellular Ca2+ chelation with BAPTA-AM, calmodulin inhibitors, or a combination of the inhibitors of protein kinase C (PKC) and calmodulin-dependent kinase II (CaMK II). In contrast, control D-[3H]aspartate release activated by the substantial hyposmotic swelling showed little (≤25% inhibition) sensitivity to the same pharmacological agents. These data indicate that ATP regulates VRAC activity via two separate Ca2+-sensitive signaling cascades involving PKC and CaMK II and that cell swelling per se activates VRACs via a separate Ca2+/calmodulin-independent signaling mechanism. Ca2+-dependent organic osmolyte release via VRACs may contribute to the physiological functions of these channels in the brain, including astrocyte-tu-neuron intercellular communication. [ABSTRACT FROM AUTHOR]

Examines the regulatory activity of adenosine triphosphate (ATP) in the excitatory amino acid (EAA) release from astrocytes. Mechanism of ATP release in the brain; Activation of EAA release by exogenous ATP; Degradation of the ATP effect by osmolarity elevation.

Summary: Purpose: The aim of this article is to review the literature on the effects of psychostimulants in epileptic subjects in order to reach a consensus statement regarding the use or abuse of these substances. Methods: Psychostimulant substances have been considered the drugs that share the ability to produce excitation of the CNS leading to convulsions. The stimulation may be at cortical, brainstem, or spinal levels. In this article, the following cortical stimulants are analyzed and discussed: cocaine, amphetamine and related agents, caffeine, cannabinoids, and psychedelic drugs. This review is based on research done using pharmacological textbooks and Medline. Results: The use of cocaine is associated with the occurrence of seizures. The reported frequency varies from 1% to 40% of addicted subjects, based on the typology of the considered study. Amphetamines and related drugs rarely induce epileptic seizures at therapeutic doses, but seizures may occur after the first dosing. Caffeine at high doses may induce epileptic seizures because of its adenosine receptor-antagonizing properties. Marijuana, at variance with other psychostimulants, owing to its serotonin-mediated anticonvulsant action, could have a medical use for the treatment of epilepsy. Psychedelic compounds rarely induce epileptic seizures, but the most common clinical CNS complication after ingestion of ecstasy is the occurrence of seizures. Conclusions: The use of psychostimulants, except for marijuana, can induce single or multiple seizures in healthy subjects. [ABSTRACT FROM AUTHOR]