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Nguyen HTT, Jang SH, Park SJ, Cho DH, Han SK. Potentiation of the Glycine Response by Bisphenol A, an Endocrine Disrupter, on the Substantia Gelatinosa Neurons of the Trigeminal Subnucleus Caudalis in Mice. Chem Res Toxicol 2020; 33:782-788. [PMID: 31997638 DOI: 10.1021/acs.chemrestox.9b00405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lamina II, also called the substantia gelatinosa (SG) of the medullary dorsal horn (the trigeminal subnucleus caudalis, Vc), is thought to play an essential role in the control of orofacial nociception because it receives the nociceptive signals from primary afferents, including thin myelinated Aδ- and unmyelinated C-fibers. Glycine, the main inhibitory neurotransmitter in the central nervous system, plays an essential role in the transference of nociceptive messages from the periphery to higher brain regions. Bisphenol A (BPA) is reported to alter the morphological and functional characteristics of neuronal cells and to be an effector of a great number of ion channels in the central nervous system. However, the electrophysiological effects of BPA on the glycine receptors of SG neurons in the Vc have not been well studied. Therefore, in this study, we used the whole-cell patch-clamp technique to determine the effect of BPA on the glycine response in SG neurons of the Vc in male mice. We demonstrated that in early neonatal mice (0-3 postnatal day mice), BPA did not affect the glycine-induced inward current. However, in the juvenile and adult groups, BPA enhanced the glycine-mediated responses. Heteromeric glycine receptors were involved in the modulation by BPA. The interaction between BPA and glycine appears to have a significant role in regulating transmission in the nociceptive pathway.
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Affiliation(s)
- Hoang Thi Thanh Nguyen
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea.,Faculty of Odonto-Stomatology, Hue University of Medicine and Pharmacy, Hue University, Hue, Vietnam
| | - Seon Hui Jang
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea
| | - Soo Joung Park
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea
| | - Dong Hyu Cho
- Department of Obstetrics and Gynecology, Jeonbuk National University Medical School, Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute and Institute for Medical Sciences, Jeonbuk National University Hospital, Jeonju, 54907, Republic of Korea
| | - Seong Kyu Han
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea
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Nguyen HTT, Cho DH, Jang SH, Han SK, Park SJ. Potentiation of the glycine response by serotonin on the substantia gelatinosa neurons of the trigeminal subnucleus caudalis in mice. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2019; 23:271-279. [PMID: 31297011 PMCID: PMC6609265 DOI: 10.4196/kjpp.2019.23.4.271] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 06/05/2019] [Accepted: 06/07/2019] [Indexed: 01/06/2023]
Abstract
The lamina II, also called the substantia gelatinosa (SG), of the trigeminal subnucleus caudalis (Vc), is thought to play an essential role in the control of orofacial nociception. Glycine and serotonin (5-hydroxytryptamine, 5-HT) are the important neurotransmitters that have the individual parts on the modulation of nociceptive transmission. However, the electrophysiological effects of 5-HT on the glycine receptors on SG neurons of the Vc have not been well studied yet. For this reason, we applied the whole-cell patch clamp technique to explore the interaction of intracellular signal transduction between 5-HT and the glycine receptors on SG neurons of the Vc in mice. In nine of 13 neurons tested (69.2%), pretreatment with 5-HT potentiated glycine-induced current (IGly). Firstly, we examined with a 5-HT1 receptor agonist (8-OH-DPAT, 5-HT1/7 agonist, co-applied with SB-269970, 5-HT7 antagonist) and antagonist (WAY-100635), but 5-HT1 receptor agonist did not increase IGly and in the presence of 5-HT1 antagonist, the potentiation of 5-HT on IGly still happened. However, an agonist (α-methyl-5-HT) and antagonist (ketanserin) of the 5-HT2 receptor mimicked and inhibited the enhancing effect of 5-HT on IGly in the SG neurons, respectively. We also verified the role of the 5-HT7 receptor by using a 5-HT7 antagonist (SB-269970) but it also did not block the enhancement of 5-HT on IGly. Our study demonstrated that 5-HT facilitated IGly in the SG neurons of the Vc through the 5-HT2 receptor. The interaction between 5-HT and glycine appears to have a significant role in modulating the transmission of the nociceptive pathway.
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Affiliation(s)
- Hoang Thi Thanh Nguyen
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju 54896, Korea
| | - Dong Hyu Cho
- Department of Obstetrics and Gynecology, Chonbuk National University Hospital and School of Medicine, Jeonju 54896, Korea
| | - Seon Hui Jang
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju 54896, Korea
| | - Seong Kyu Han
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju 54896, Korea
| | - Soo Joung Park
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju 54896, Korea
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Boison D. The Biochemistry and Epigenetics of Epilepsy: Focus on Adenosine and Glycine. Front Mol Neurosci 2016; 9:26. [PMID: 27147960 PMCID: PMC4829603 DOI: 10.3389/fnmol.2016.00026] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/31/2016] [Indexed: 12/14/2022] Open
Abstract
Epilepsy, one of the most prevalent neurological conditions, presents as a complex disorder of network homeostasis characterized by spontaneous non-provoked seizures and associated comorbidities. Currently used antiepileptic drugs have been designed to suppress neuronal hyperexcitability and thereby to suppress epileptic seizures. However, the current armamentarium of antiepileptic drugs is not effective in over 30% of patients, does not affect the comorbidities of epilepsy, and does not prevent the development and progression of epilepsy (epileptogenesis). Prevention of epilepsy and its progression remains the Holy Grail for epilepsy research and therapy development, requiring novel conceptual advances to find a solution to this urgent medical need. The methylation hypothesis of epileptogenesis suggests that changes in DNA methylation are implicated in the progression of the disease. In particular, global DNA hypermethylation appears to be associated with chronic epilepsy. Clinical as well as experimental evidence demonstrates that epilepsy and its progression can be prevented by biochemical manipulations and those that target previously unrecognized epigenetic functions contributing to epilepsy development and maintenance of the epileptic state. This mini-review will discuss, epigenetic mechanisms implicated in epileptogenesis and biochemical interactions between adenosine and glycine as a conceptual advance to understand the contribution of maladaptive changes in biochemistry as a major contributing factor to the development of epilepsy. New findings based on biochemical manipulation of the DNA methylome suggest that: (i) epigenetic mechanisms play a functional role in epileptogenesis; and (ii) therapeutic reconstruction of the epigenome is an effective antiepileptogenic therapy.
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Affiliation(s)
- Detlev Boison
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute Portland, OR, USA
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4
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van de Kerkhof NW, Fekkes D, van der Heijden FM, Hoogendijk WJ, Stöber G, Egger JI, Verhoeven WM. Cycloid psychoses in the psychosis spectrum: evidence for biochemical differences with schizophrenia. Neuropsychiatr Dis Treat 2016; 12:1927-33. [PMID: 27536115 PMCID: PMC4977096 DOI: 10.2147/ndt.s101317] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Cycloid psychoses (CP) differ from schizophrenia regarding symptom profile, course, and prognosis and over many decades they were thought to be a separate entity within the psychosis spectrum. As to schizophrenia, research into the pathophysiology has focused on dopamine, brain-derived neurotrophic factor, and glutamate signaling in which, concerning the latter, the N-methyl-d-aspartate receptor plays a crucial role. The present study aims to determine whether CP can biochemically be delineated from schizophrenia. Eighty patients referred for psychotic disorders were assessed with the Comprehensive Assessment of Symptoms and History, and (both at inclusion and after 6 weeks of antipsychotic treatment) with the Positive and Negative Syndrome Scale and Clinical Global Impression. From 58 completers, 33 patients were diagnosed with schizophrenia and ten with CP according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, and Leonhard criteria, respectively. Fifteen patients were diagnosed with other disorders within the psychosis spectrum. At both time points, blood levels of the dopamine metabolite homovanillic acid, brain-derived neurotrophic factor, and amino acids related to glutamate neurotransmission were measured and compared with a matched control sample. Patients with CP showed a significantly better response to antipsychotic treatment as compared to patients with schizophrenia. In CP, glycine levels were elevated and tryptophan levels were lowered as compared to schizophrenia. Glutamate levels were increased in both patient groups as compared to controls. These results, showing marked differences in both treatment outcome and glutamate-related variable parameters, may point at better neuroplasticity in CP, necessitating demarcation of this subgroup within the psychosis spectrum.
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Affiliation(s)
- Nora Wa van de Kerkhof
- Vincent van Gogh Institute for Psychiatry, Centre of Excellence for Neuropsychiatry, Venray; Department of Psychiatry
| | - Durk Fekkes
- Department of Psychiatry; Department of Clinical Chemistry, Erasmus University Medical Center, Rotterdam, The Netherlands
| | | | | | - Gerald Stöber
- Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
| | - Jos Im Egger
- Vincent van Gogh Institute for Psychiatry, Centre of Excellence for Neuropsychiatry, Venray; Behavioural Science Institute; Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Willem Ma Verhoeven
- Vincent van Gogh Institute for Psychiatry, Centre of Excellence for Neuropsychiatry, Venray; Department of Psychiatry
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Shen HY, van Vliet EA, Bright KA, Hanthorn M, Lytle NK, Gorter J, Aronica E, Boison D. Glycine transporter 1 is a target for the treatment of epilepsy. Neuropharmacology 2015; 99:554-65. [PMID: 26302655 PMCID: PMC4655139 DOI: 10.1016/j.neuropharm.2015.08.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/27/2015] [Accepted: 08/19/2015] [Indexed: 11/17/2022]
Abstract
Glycine is the major inhibitory neurotransmitter in brainstem and spinal cord, whereas in hippocampus glycine exerts dual modulatory roles on strychnine-sensitive glycine receptors and on the strychnine-insensitive glycineB site of the N-methyl-D-aspartate receptor (NMDAR). In hippocampus, the synaptic availability of glycine is largely under control of glycine transporter 1 (GlyT1). Since epilepsy is a disorder of disrupted network homeostasis affecting the equilibrium of various neurotransmitters and neuromodulators, we hypothesized that changes in hippocampal GlyT1 expression and resulting disruption of glycine homeostasis might be implicated in the pathophysiology of epilepsy. Using two different rodent models of temporal lobe epilepsy (TLE)--the intrahippocampal kainic acid model of TLE in mice, and the rat model of tetanic stimulation-induced TLE--we first demonstrated robust overexpression of GlyT1 in the hippocampal formation, suggesting dysfunctional glycine signaling in epilepsy. Overexpression of GlyT1 in the hippocampal formation was corroborated in human TLE samples by quantitative real time PCR. In support of a role of dysfunctional glycine signaling in the pathophysiology of epilepsy, both the genetic deletion of GlyT1 in hippocampus and the GlyT1 inhibitor LY2365109 increased seizure thresholds in mice. Importantly, chronic seizures in the mouse model of TLE were robustly suppressed by systemic administration of the GlyT1 inhibitor LY2365109. We conclude that GlyT1 overexpression in the epileptic brain constitutes a new target for therapeutic intervention, and that GlyT1 inhibitors constitute a new class of antiictogenic drugs. These findings are of translational value since GlyT1 inhibitors are already in clinical development to treat cognitive symptoms in schizophrenia.
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Affiliation(s)
- Hai-Ying Shen
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR 97232, USA
| | - Erwin A van Vliet
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Kerry-Ann Bright
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR 97232, USA
| | - Marissa Hanthorn
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR 97232, USA
| | - Nikki K Lytle
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR 97232, USA
| | - Jan Gorter
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, The Netherlands
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, The Netherlands; Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, The Netherlands; SEIN - Stichting Epilepsie Instellingen Nederland, Heemstede, The Netherlands
| | - Detlev Boison
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR 97232, USA.
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Wischhof L, Irrsack E, Osorio C, Koch M. Prenatal LPS-exposure--a neurodevelopmental rat model of schizophrenia--differentially affects cognitive functions, myelination and parvalbumin expression in male and female offspring. Prog Neuropsychopharmacol Biol Psychiatry 2015; 57:17-30. [PMID: 25455585 DOI: 10.1016/j.pnpbp.2014.10.004] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/08/2014] [Accepted: 10/10/2014] [Indexed: 01/15/2023]
Abstract
Maternal infection during pregnancy increases the risk for the offspring to develop schizophrenia. Gender differences can be seen in various features of the illness and sex steroid hormones (e.g. estrogen) have strongly been implicated in the disease pathology. In the present study, we evaluated sex differences in the effects of prenatal exposure to a bacterial endotoxin (lipopolysaccharide, LPS) in rats. Pregnant dams received LPS-injections (100 μg/kg) at gestational day 15 and 16. The offspring was then tested for prepulse inhibition (PPI), locomotor activity, anxiety-like behavior and object recognition memory at various developmental time points. At postnatal day (PD) 33 and 60, prenatally LPS-exposed rats showed locomotor hyperactivity which was similar in male and female offspring. Moreover, prenatal LPS-treatment caused PPI deficits in pubertal (PD45) and adult (PD90) males while PPI impairments were found only at PD45 in prenatally LPS-treated females. Following prenatal LPS-administration, recognition memory for objects was impaired in both sexes with males being more severely affected. Additionally, we assessed prenatal infection-induced alterations of parvalbumin (Parv) expression and myelin fiber density. Male offspring born to LPS-challenged mothers showed decreased myelination in cortical and limbic brain regions as well as reduced numbers of Parv-expressing cells in the medial prefrontal cortex (mPFC), hippocampus and entorhinal cortex. In contrast, LPS-exposed female rats showed only a modest decrease in myelination and Parv immunoreactivity. Collectively, our data indicate that some of the prenatal immune activation effects are sex dependent and further strengthen the importance of taking into account gender differences in animal models of schizophrenia.
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Affiliation(s)
- Lena Wischhof
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany.
| | - Ellen Irrsack
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany
| | - Carmen Osorio
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany
| | - Michael Koch
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany
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Si D, Yang P, Jiang R, Zhou H, Wang H, Zhang Y. Improved cognitive outcome after progesterone administration is associated with protecting hippocampal neurons from secondary damage studied in vitro and in vivo. Behav Brain Res 2014; 264:135-42. [PMID: 24518203 DOI: 10.1016/j.bbr.2014.01.049] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 01/28/2014] [Accepted: 01/31/2014] [Indexed: 12/20/2022]
Abstract
Previous studies reported that progesterone could improve cognitive outcome following TBI. Moreover, some evidence implied that the hippocampus is associated with cognitive function. The aim of this study was to investigate the neuroprotective effects of progesterone on hippocampal neurons in vitro and in vivo, and its influence on the cognitive outcome. In vitro, the model of primary cultured hippocampal neurons against glutamate-induced excitotoxic damage was used. After 10-day culture, neurons were pretreated with progesterone in a concentration 10 ng/ml, 48 h before a 5-min exposure to 200 μmol/l glutamate. Then 24h after glutamate exposure, the nerve cells were observed and LDH was detected. The results showed progesterone protected the cultured hippocampal neurons morphology and significantly reduced the amount of LDH. In vivo, the model of TBI was established by modified Feeney's weight-dropping method. The progesterone was given in a dose of 16 mg/kg by intraperitoneal injection 1h post injury and subsequent injections subcutaneously at 6h and 12h after TBI. Brain samples were extracted at 24h after injury. Histology and the iNOS expression were examined by Nissl stain, immunohistochemistry and Western blot. The cognitive outcome was assessed by Morris water maze test (MWM). The results revealed that the neuronal cell damage and the expression of iNOS in the hippocampus CA1 were significantly decreased after progesterone administration. Progesterone significantly improved cognitive outcome after TBI. The results suggest that the positive effects of progesterone on cognitive outcome may be linked to protecting hippocampal neurons from secondary damage.
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Affiliation(s)
- Daowen Si
- School of Basic Medical Sciences, Hebei United University, Tangshan 063000, Hebei, China.
| | - Peng Yang
- Department of Neurosurgery, Affiliated Hospital of Hebei United University, Tangshan 063000, Hebei, China
| | - Rongcai Jiang
- Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin 300000, China
| | - Hongxia Zhou
- School of Basic Medical Sciences, Hebei United University, Tangshan 063000, Hebei, China
| | - Haitao Wang
- School of Basic Medical Sciences, Hebei United University, Tangshan 063000, Hebei, China.
| | - Yuxin Zhang
- School of Basic Medical Sciences, Hebei United University, Tangshan 063000, Hebei, China
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Activation of glycine and extrasynaptic GABA(A) receptors by taurine on the substantia gelatinosa neurons of the trigeminal subnucleus caudalis. Neural Plast 2013; 2013:740581. [PMID: 24379976 PMCID: PMC3863572 DOI: 10.1155/2013/740581] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/05/2013] [Accepted: 11/12/2013] [Indexed: 11/23/2022] Open
Abstract
The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) has been known for the processing and transmission of orofacial nociceptive information. Taurine, one of the most plentiful free amino-acids in humans, has proved to be involved in pain modulation. In this study, using whole-cell patch clamp technique, we investigated the direct membrane effects of taurine and the action mechanism behind taurine-mediated responses on the SG neurons of the Vc. Taurine showed non-desensitizing and repeatable membrane depolarizations and inward currents which remained in the presence of amino-acid receptors blocking cocktail (AARBC) with tetrodotoxin, indicating that taurine acts directly on the postsynaptic SG neurons. Further, application of taurine at different doses (10 μM to 3 mM) showed a concentration dependent depolarizations and inward currents with the EC50 of 84.3 μM and 723 μM, respectively. Taurine-mediated responses were partially blocked by picrotoxin (50 μM) and almost completely blocked by strychnine (2 μM), suggesting that taurine-mediated responses are via glycine receptor (GlyR) activation. In addition, taurine (1 mM) activated extrasynaptic GABAA receptor (GABAAR)-mediated currents. Taken together, our results indicate that taurine can be a target molecule for orofacial pain modulation through the activation of GlyRs and/or extrasynaptic GABAARs on the SG neurons.
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Kobayashi K, Liu CC, Jensen AL, Vitek JL, Mari Z, Lenz FA. Thalamic post-inhibitory bursting occurs in patients with organic dystonia more often than controls. Brain Res 2013; 1541:81-91. [PMID: 24125808 DOI: 10.1016/j.brainres.2013.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 10/03/2013] [Accepted: 10/04/2013] [Indexed: 11/19/2022]
Abstract
We now test the hypothesis that post-inhibitory bursting in the human pallidal receiving nucleus of the thalamus (ventral oral) mediates inhibitory pallido-thalamic transmission during dystonia. We have compared thalamic single neuron activity in nine patients with organic dystonia to that in a patient with psychogenic dystonia (Psyd) and in healthy waking monkeys. In organic dystonia, EMG power is commonly concentrated at the lowest frequency of the smoothed autopower spectrum (0.39Hz). Therefore, segments of spike trains with a signal-to-noise ratio ≥2 at 0.39Hz were termed dystonia frequency (DF) segments, which occurred more commonly during dystonia related to movement. Those with a SNR<2 were termed non-dystonia frequency (nDF) segments, which were associated with spontaneous dystonia. We concentrated on nDF activity since neuronal activity in our controls was measured at rest. Neuronal spike trains were categorized into those with post-inhibitory bursts (G, grouped), with single spikes (NG, non-grouped), or with both single spikes and bursts (I, intermediate). nDF spike trains in ventral oral had more G category firing in dystonia than in controls. The burst rate and the pre-burst silent period in nDF firing of organic dystonia were consistently greater than those of both the monkeys and the patient with Psyd. The distribution of the pre-burst silent period was bimodal with a longer mode of approximately GABAb (gamma amino butyric acid receptor-type b) duration. These results demonstrate distinct differences of post-inhibitory bursting in organic dystonia versus controls. The presence of inhibitory events consistent with GABAb duration suggests interventions for treatment of dystonia.
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Affiliation(s)
- K Kobayashi
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Division of Neurosurgery, Department of Neurological Surgery, Nihon University School of Medicine, Tokyo, Japan
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Silverman JL, Oliver CF, Karras MN, Gastrell PT, Crawley JN. AMPAKINE enhancement of social interaction in the BTBR mouse model of autism. Neuropharmacology 2013; 64:268-82. [PMID: 22801296 PMCID: PMC3445667 DOI: 10.1016/j.neuropharm.2012.07.013] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 07/05/2012] [Accepted: 07/06/2012] [Indexed: 12/16/2022]
Abstract
Autism is a neurodevelopmental disorder in which the first diagnostic symptom is unusual reciprocal social interactions. Approximately half of the children diagnosed with an autism spectrum disorder also have intellectual impairments. General cognitive abilities may be fundamental to many aspects of social cognition. Cognitive enhancers could conceivably be of significant benefit to children and adults with autism. AMPAKINE compounds are a novel class of pharmacological agents that act as positive modulators of AMPA receptors to enhance excitatory glutamatergic neurotransmission. This class of compounds was reported to improve learning and memory in several rodent and non-human primate tasks, and to normalize respiratory abnormalities in a mouse model of Rett syndrome. Here we evaluate the actions of AMPA compounds in adult male and female BTBR mice, a well characterized mouse model of autism. Acute treatment with CX1837 and CX1739 reversed the deficit in sociability in BTBR mice on the most sensitive parameter, time spent sniffing a novel mouse as compared to time spent sniffing a novel object. The less sensitive parameter, time in the chamber containing the novel mouse versus time in the chamber containing the novel object, was not rescued by CX1837 or CX1739 treatment. Preliminary data with CX546, in which β-cyclodextrin was the vehicle, revealed behavioral effects of the acute intraperitoneal and oral administration of vehicle alone. To circumvent the artifacts introduced by the vehicle administration, we employed a novel treatment regimen using pellets of peanut butter for drug delivery. Absence of vehicle treatment effects when CX1837 and CX1739 were given in the peanut butter pellets, to multiple cohorts of BTBR and B6 control mice, confirmed that the pharmacologically-induced improvements in sociability in BTBR were not confounded by the administration procedures. The highest dose of CX1837 improved the cognitive deficit in novel object recognition in BTBR. No drug effects were detected on the high levels of repetitive self-grooming in BTBR. In open field tests, CX1837 and CX1739 did not induce hyperactivity or sedation in either strain. It is interesting to speculate that the ability of CX1837 and CX1739 to restore aspects of sociability in BTBR mice could utilize synaptic mechanisms regulating social cognition, suggesting a potential pharmacological target for interventions to treat symptoms of autism. This article is part of a Special Issue entitled 'Cognitive Enhancers'.
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MESH Headings
- Animals
- Autistic Disorder/drug therapy
- Autistic Disorder/physiopathology
- Behavior, Animal/drug effects
- Cognition Disorders/etiology
- Cognition Disorders/prevention & control
- Dioxoles/administration & dosage
- Dioxoles/adverse effects
- Dioxoles/therapeutic use
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Drugs, Investigational/administration & dosage
- Drugs, Investigational/adverse effects
- Drugs, Investigational/therapeutic use
- Excitatory Amino Acid Agonists/administration & dosage
- Excitatory Amino Acid Agonists/adverse effects
- Excitatory Amino Acid Agonists/therapeutic use
- Female
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred Strains
- Molecular Targeted Therapy
- Nootropic Agents/administration & dosage
- Nootropic Agents/adverse effects
- Nootropic Agents/therapeutic use
- Piperidines/administration & dosage
- Piperidines/adverse effects
- Piperidines/therapeutic use
- Random Allocation
- Receptors, AMPA/agonists
- Recognition, Psychology/drug effects
- Social Behavior
- Social Behavior Disorders/etiology
- Social Behavior Disorders/prevention & control
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Affiliation(s)
- J L Silverman
- Laboratory of Behavioral Neuroscience, National Institute of Mental Health, Bethesda, MD 20892-3730, USA.
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Morrow JA, Gilfillan R, Neale SA. Glutamatergic Approaches for the Treatment of Schizophrenia. DRUG DISCOVERY FOR PSYCHIATRIC DISORDERS 2012. [DOI: 10.1039/9781849734943-00056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system and plays a key role in most aspects of normal brain function including cognition, learning and memory. Dysfunction of glutamatergic neurotransmission has been implicated in a number of neurological and psychiatric disorders with a growing body of evidence suggesting that hypofunction of glutamatergic neurotransmission via the N-methyl-d-aspartate (NMDA) receptor plays an important role in the pathophysiology of schizophrenia. It thus follows that potentiation of NMDA receptor function via pharmacological manipulation may provide therapeutic utility for the treatment of schizophrenia and a number of different approaches are currently being pursued by the pharmaceutical industry with this aim in mind. These include strategies that target the glycine/d-serine site of the NMDA receptor (glycine transporter GlyT1, d-serine transporter ASC-1 and d-amino acid oxidase (DAAO) inhibitors) together with those aimed at enhancing glutamatergic neurotransmission via modulation of AMPA receptor and metabotropic glutamate receptor function. Such efforts are now beginning to bear fruit with compounds such as the GlyT1 inhibitor RG1678 and mGlu2 agonist LY2140023 proving to have clinical meaningful effects in phase II clinical trials. While more studies are required to confirm long-term efficacy, functional outcome and safety in schizophrenic agents, these agents hold real promise for addressing unmet medical needs, in particular refractory negative and cognitive symptoms, not currently addressed by existing antipsychotic agents.
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Affiliation(s)
- John A. Morrow
- Neuroscience and Ophthalmology, Merck Research Laboratories 2015 Galloping Hill Road, Kenilworth, New Jersey 07033 USA
| | - Robert Gilfillan
- Discovery Chemistry, Merck Research Laboratories 770 Sumneytown Pike, West Point, Pennsylvania 19486 USA
| | - Stuart A. Neale
- Neurexpert Ltd Ground Floor, 2 Woodberry Grove, North Finchley, London, N12 0DR UK
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D'Souza DC, Singh N, Elander J, Carbuto M, Pittman B, de Haes JU, Sjogren M, Peeters P, Ranganathan M, Schipper J. Glycine transporter inhibitor attenuates the psychotomimetic effects of ketamine in healthy males: preliminary evidence. Neuropsychopharmacology 2012; 37:1036-46. [PMID: 22113087 PMCID: PMC3280648 DOI: 10.1038/npp.2011.295] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Enhancing glutamate function by stimulating the glycine site of the NMDA receptor with glycine, D-serine, or with drugs that inhibit glycine reuptake may have therapeutic potential in schizophrenia. The effects of a single oral dose of cis-N-methyl-N-(6-methoxy-1-phenyl-1,2,3,4-tetrahydronaphthalen-2-ylmethyl) amino-methylcarboxylic acid hydrochloride (Org 25935), a glycine transporter-1 (GlyT1) inhibitor, and placebo pretreatment on ketamine-induced schizophrenia-like psychotic symptoms, perceptual alterations, and subjective effects were evaluated in 12 healthy male subjects in a randomized, counter-balanced, within-subjects, crossover design. At 2.5 h after administration of the Org 25935 or placebo, subjects received a ketamine bolus and constant infusion lasting 100 min. Psychotic symptoms, perceptual, and a number of subjective effects were assessed repeatedly before, several times during, and after completion of ketamine administration. A cognitive battery was administered once per test day. Ketamine produced behavioral, subjective, and cognitive effects consistent with its known effects. Org 25935 reduced the ketamine-induced increases in measures of psychosis (Positive and Negative Syndrome Scale (PANSS)) and perceptual alterations (Clinician Administered Dissociative Symptoms Scale (CADSS)). The magnitude of the effect of Org 25935 on ketamine-induced increases in Total PANSS and CADSS Clinician-rated scores was 0.71 and 0.98 (SD units), respectively. None of the behavioral effects of ketamine were increased by Org 25935 pretreatment. Org 25935 worsened some aspects of learning and delayed recall, and trended to improve choice reaction time. This study demonstrates for the first time in humans that a GlyT1 inhibitor reduces the effects induced by NMDA receptor antagonism. These findings provide preliminary support for further study of the antipsychotic potential of GlyT1 inhibitors.
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Affiliation(s)
- Deepak Cyril D'Souza
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06516, USA.
| | - Nagendra Singh
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,VA Connecticut Healthcare System, West Haven, CT, USA
| | - Jacqueline Elander
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,VA Connecticut Healthcare System, West Haven, CT, USA
| | - Michelle Carbuto
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,VA Connecticut Healthcare System, West Haven, CT, USA,Clinical Neuroscience Research Unit, New Haven, CT, USA
| | - Brian Pittman
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,Clinical Neuroscience Research Unit, New Haven, CT, USA
| | | | - Magnus Sjogren
- Merck, Sharpe and Dohme (formerly Organon NV), Oss, The Netherlands
| | - Pierre Peeters
- Merck, Sharpe and Dohme (formerly Organon NV), Oss, The Netherlands
| | - Mohini Ranganathan
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,VA Connecticut Healthcare System, West Haven, CT, USA,Clinical Neuroscience Research Unit, New Haven, CT, USA
| | - Jacques Schipper
- Merck, Sharpe and Dohme (formerly Organon NV), Oss, The Netherlands
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Dubroqua S, Serrano L, Boison D, Feldon J, Gargiulo PA, Yee BK. Intact working memory in the absence of forebrain neuronal glycine transporter 1. Behav Brain Res 2012; 230:208-14. [PMID: 22342492 DOI: 10.1016/j.bbr.2012.01.061] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/27/2012] [Accepted: 01/31/2012] [Indexed: 01/26/2023]
Abstract
Glycine transporter 1 (GlyT1) is a potential pharmacological target to ameliorate memory deficits attributable to N-methyl-d-aspartate receptor (NMDAR) hypofunction. Disruption of glycine-reuptake near excitatory synapses is expected to enhance NMDAR function by increasing glycine-B site occupancy. Genetic models with conditional GlyT1 deletion restricted to forebrain neurons have yielded several promising promnesic effects, yet its impact on working memory function remains essentially unanswered because the previous attempt had yielded un-interpretable outcomes. The present study clarified this important outstanding lacuna using a within-subject multi-test approach. Here, a consistent lack of effects was convincingly demonstrated across three working memory tests - the radial arm maze, the cheeseboard maze, and the water maze. These null outcomes contrasted with the phenotype of enhanced working memory performance seen in mutant mice with GlyT1 deletion extended to cortical/hippocampal glial cells. It follows that glial-based GlyT1 might be more closely linked to the modulation of working memory function, and raises the possibility that neuronal and glial GlyT1 may regulate cognitive functions via dissociable mechanisms.
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Affiliation(s)
- Sylvain Dubroqua
- Laboratory of Behavioral Neurobiology, ETH Zurich, Schorenstrasse 16, CH-8603 Schwerzenbach, Switzerland
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14
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Liu CC, Franaszczuk P, Crone NE, Jouny C, Lenz FA. Studies of properties of "Pain Networks" as predictors of targets of stimulation for treatment of pain. Front Integr Neurosci 2011; 5:80. [PMID: 22164137 PMCID: PMC3230069 DOI: 10.3389/fnint.2011.00080] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 11/19/2011] [Indexed: 12/29/2022] Open
Abstract
Two decades of functional imaging studies have demonstrated pain-related activations of primary somatic sensory cortex (S1), parasylvian cortical structures (PS), and medial frontal cortical structures (MF), which are often described as modules in a "pain network." The directionality and temporal dynamics of interactions between and within the cortical and thalamic modules are uncertain. We now describe our studies of these interactions based upon recordings of local field potentials (LFPs) carried out in an epilepsy monitoring unit over the one week period between the implantation and removal of cortical electrodes during the surgical treatment of epilepsy. These recordings have unprecedented clarity and resolution for the study of LFPs related to the experimental pain induced by cutaneous application of a Thulium YAG laser. We also used attention and distraction as behavioral probes to study the psychophysics and neuroscience of the cortical "pain network." In these studies, electrical activation of cortex was measured by event-related desynchronization (ERD), over SI, PS, and MF modules, and was more widespread and intense while attending to painful stimuli than while being distracted from them. This difference was particularly prominent over PS. In addition, greater perceived intensity of painful stimuli was associated with more widespread and intense ERD. Connectivity of these modules was then examined for dynamic causal interactions within and between modules by using the Granger causality (GRC). Prior to the laser stimuli, a task involving attention to the painful stimulus consistently increased the number of event-related causality (ERC) pairs both within the SI cortex, and from SI upon PS (SI > PS). After the laser stimulus, attention to a painful stimulus increased the number of ERC pairs from SI > PS, and SI > MF, and within the SI module. LFP at some electrode sites (critical sites) exerted ERC influences upon signals at multiple widespread electrodes, both in other cortical modules and within the module where the critical site was located. In summary, critical sites and SI modules may bind the cortical modules together into a "pain network," and disruption of that network by stimulation might be used to treat pain. These results in humans may be uniquely useful to design and optimize anatomically based pain therapies, such as stimulation of the S1 or critical sites through transcutaneous magnetic fields or implanted electrodes.
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Affiliation(s)
- C. C. Liu
- Department of Neurosurgery, Johns Hopkins HospitalBaltimore, MD, USA
| | - P. Franaszczuk
- Department of Neurology, Johns Hopkins HospitalBaltimore, MD, USA
- US Army Research Laboratory, Human Research and Engineering DirectorateAberdeen Proving Ground, MD, USA
| | - N. E. Crone
- Department of Neurology, Johns Hopkins HospitalBaltimore, MD, USA
| | - C. Jouny
- Department of Neurology, Johns Hopkins HospitalBaltimore, MD, USA
| | - F. A. Lenz
- Department of Neurosurgery, Johns Hopkins HospitalBaltimore, MD, USA
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15
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Simultaneous quantification of d- vs. l-serine, taurine, kynurenate, phosphoethanolamine and diverse amino acids in frontocortical dialysates of freely-moving rats: Differential modulation by N-methyl-d-aspartate (NMDA) and other pharmacological agents. J Neurosci Methods 2011; 202:143-57. [DOI: 10.1016/j.jneumeth.2011.08.040] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 08/08/2011] [Accepted: 08/25/2011] [Indexed: 01/18/2023]
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Jurd R, Moss SJ. Impaired GABA(A) receptor endocytosis and its correlation to spatial memory deficits. Commun Integr Biol 2011; 3:176-8. [PMID: 20585515 DOI: 10.4161/cib.3.2.10742] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Accepted: 11/23/2009] [Indexed: 11/19/2022] Open
Abstract
GABA(A) receptors mediate the majority of fast synaptic inhibition in the mammalian brain. Mechanisms that regulate GABA(A) function are thus of critical importance in modulating overall synaptic inhibition. Phosphorylation of GABA(A) receptor subunits is one such mechanism that leads to the dynamic modulation of GABA(A) receptor function. In particular, phosphorylation of tyrosine residues 365 and 367 (Y365, Y367) within the gamma2 subunit of GABA(A) receptors has been shown in previous in vitro studies to negatively regulate clathrin-dependent endocytosis of GABA(A) receptors and to enhance the efficacy of synaptic inhibition. With the aim of investigating the impact of this phosphorylation-dependent modulation of GABA(A) receptors on animal behavior, we recently developed a knock-in mouse in which these critical tyrosine residues within the gamma2 subunit have been mutated to phenylalanines (Y365/7F). These animals exhibited enhanced GABA(A) receptor accumulation at postsynaptic inhibitory synaptic specializations on pyramidal neurons within the hippocampus, primarily due to aberrant trafficking within the endocytic pathway. We found that this enhanced inhibition correlated with a specific deficit in spatial memory in these mice, without modifying a number of other behavioral paradigms. Here, we summarize our recently reported observations and further discuss their possible implications.
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Affiliation(s)
- Rachel Jurd
- Department of Neuroscience; School of Medicine; Tufts University; Boston, MA USA
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Papaleo F, Lipska BK, Weinberger DR. Mouse models of genetic effects on cognition: relevance to schizophrenia. Neuropharmacology 2011; 62:1204-20. [PMID: 21557953 DOI: 10.1016/j.neuropharm.2011.04.025] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2010] [Revised: 04/08/2011] [Accepted: 04/20/2011] [Indexed: 01/27/2023]
Abstract
Cognitive dysfunction is a core feature of schizophrenia. Growing evidence indicates that a wide variety of genetic mutations and polymorphisms impact cognition and may thus be implicated in various aspects of this mental disorder. Despite differences between human and rodent brain structure and function, genetic mouse models have contributed critical information about brain mechanisms involved in cognitive processes. Here, we summarize discoveries of genetic modifications in mice that impact cognition. Based on functional hypotheses, gene modifications within five model systems are described: 1) dopamine (D1, D2, D3, D4, D5, DAT, COMT, MAO); 2) glutamate (GluR-A, NR1, NR2A, NR2B, GRM2, GRM3, GLAST); 3) GABA (α(5), γ(2), α(4), δGABA(A), GABA(B(1)), GAT1); 4) acetylcholine (nAChRβ2, α7, CHRM1); and 5) calcium (CaMKII-α, neurogranin, CaMKKβ, CaMKIV). We also consider other risk-associated genes for schizophrenia such as dysbindin (DTNBP1), neuregulin (NRG1), disrupted-in-schizophrenia1 (DISC1), reelin and proline dehydrogenase (PRODH). Because of the presumed importance of environmental factors, we further consider genetic modifications within the stress-sensitive systems of corticotropin-releasing factor (CRF), brain-derived neurotrophic factor (BDNF) and the endocannabinoid systems. We highlight the missing information and limitations of cognitive assays in genetically modified mice models relevant to schizophrenia pathology.
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Affiliation(s)
- Francesco Papaleo
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Via Morego 30, 16163 Genova, Italy.
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18
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Singer P, Boison D, Möhler H, Feldon J, Yee BK. Modulation of sensorimotor gating in prepulse inhibition by conditional brain glycine transporter 1 deletion in mice. Eur Neuropsychopharmacol 2011; 21:401-13. [PMID: 20647165 PMCID: PMC2980791 DOI: 10.1016/j.euroneuro.2010.06.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 06/21/2010] [Accepted: 06/23/2010] [Indexed: 01/07/2023]
Abstract
Inhibition of glycine transporter 1 (GlyT1) augments N-methyl-D-aspartate receptor (NMDAR)-mediated transmission and represents a potential antipsychotic drug target according to the NMDAR hypofunction hypothesis of schizophrenia. Preclinical evaluation of GlyT1 inhibiting drugs using the prepulse inhibition (PPI) test, however, has yielded mixed outcomes. Here, we tested for the first time the impact of two conditional knockouts of GlyT1 on PPI expression. Complete deletion of GlyT1 in the cerebral cortices confers resistance to PPI disruption induced by the NMDAR blocker MK-801 (0.2mg/kg, i.p.) without affecting PPI expression in unchallenged conditions. In contrast, restricting GlyT1 deletion to neurons in forebrain including the striatum significantly attenuated PPI, and the animals remained sensitive to the PPI-disruptive effect of MK-801 at the same dose. These results demonstrate in mice that depending on the regional and/or cell-type specificity, deletion of the GlyT1 gene could yield divergent effects on PPI.
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Affiliation(s)
- Philipp Singer
- Laboratory of Behavioural Neurobiology, Federal Institute of Technology Zurich, Schorenstrasse 16, CH-8603 Schwerzenbach, Switzerland
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19
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Adenosine hypothesis of schizophrenia--opportunities for pharmacotherapy. Neuropharmacology 2011; 62:1527-43. [PMID: 21315743 DOI: 10.1016/j.neuropharm.2011.01.048] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 01/21/2011] [Accepted: 01/28/2011] [Indexed: 12/19/2022]
Abstract
Pharmacotherapy of schizophrenia based on the dopamine hypothesis remains unsatisfactory for the negative and cognitive symptoms of the disease. Enhancing N-methyl-D-aspartate receptors (NMDAR) function is expected to alleviate such persistent symptoms, but successful development of novel clinically effective compounds remains challenging. Adenosine is a homeostatic bioenergetic network modulator that is able to affect complex networks synergistically at different levels (receptor-dependent pathways, biochemistry, bioenergetics, and epigenetics). By affecting brain dopamine and glutamate activities, it represents a promising candidate for reversing the functional imbalance in these neurotransmitter systems believed to underlie the genesis of schizophrenia symptoms, as well as restoring homeostasis of bioenergetics. Suggestion of an adenosine hypothesis of schizophrenia further posits that adenosinergic dysfunction might contribute to the emergence of multiple neurotransmitter dysfunctions characteristic of schizophrenia via diverse mechanisms. Given the importance of adenosine in early brain development and regulation of brain immune response, it also bears direct relevance to the aetiology of schizophrenia. Here, we provide an overview of the rationale and evidence in support of the therapeutic potential of multiple adenosinergic targets, including the high-affinity adenosine receptors (A(1)R and A(2A)R), and the regulatory enzyme adenosine kinase (ADK). Key preliminary clinical data and preclinical findings are reviewed.
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Abstract
Glycine transporter 1 (GLYT1) and GLYT2 are the glycine transporters in CNS. While GLYT2 is largely expressed in glycinergic neurons, GLYT1 has long been considered to be exclusively present in glial cells. There is increasing evidence that significant amounts of the 'glial' transporter also exist on neurons, particularly on pre-synaptic nerve endings of glutamatergic neurons. The functions of 'neuronal GLYT1' may be manifold and are discussed in this review. Of major interest are the interactions between neuronal GLYT1 and glutamatergic receptors of the NMDA type the activity of which is modulated not only by astrocytic GLYT1 but also by neuronal GLYT1. Pathophysiological roles and therapeutic implications of neuronal GLYT1 are emerging from recent studies with genetically modified mice, particularly with animals lacking forebrain neuron-specific GLYT1 transporters. These mutant mice exhibit promnesic phenotypes reflecting enhancement of NMDA receptor function, as it occurs following administration of GLYT1 inhibitors. Inactivation of neuronal GLYT1 in the forebrain may represent an effective therapeutic intervention for the treatment of schizophrenia.
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Affiliation(s)
- Luca Raiteri
- Department of Experimental Medicine, University of Genova, Genova, Italy.
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21
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GABAergic modulation of the 40 Hz auditory steady-state response in a rat model of schizophrenia. Int J Neuropsychopharmacol 2010; 13:487-97. [PMID: 19627651 PMCID: PMC2882653 DOI: 10.1017/s1461145709990307] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Auditory steady-state auditory responses (ASSRs), in which the evoked potential entrains to stimulus frequency and phase, are reduced in magnitude in patients with schizophrenia, particularly at 40 Hz. While the neural mechanisms responsible for ASSR generation and its perturbation in schizophrenia are unknown, it has been hypothesized that the GABAA receptor subtype may have an important role. Using an established rat model of schizophrenia, the neonatal ventral hippocampal lesion (NVHL) model, 40-Hz ASSRs were elicited from NVHL and sham rats to determine if NVHL rats show deficits comparable to schizophrenia, and to examine the role of GABAA receptors in ASSR generation. ASSR parameters were found to be stable across time in both NVHL and sham rats. Manipulation of the GABAA receptor by muscimol, a GABAA agonist, yielded a strong lesion x drug interaction, with ASSR magnitude and synchronization decreased in NVHL and increased in sham rats. The lesion x muscimol interaction was blocked by a GABAA receptor antagonist when given prior to muscimol administration, confirming the observed interaction was GABAA mediated. Together, these data suggest an alteration involving GABAA receptor function, and hence inhibitory transmission, in the neuronal networks responsible for ASSR generation in NVHL rats. These findings are consistent with prior evidence for alterations in GABA neurotransmitter systems in the NVHL model and suggest the utility of this animal modelling approach for exploring neurobiological mechanisms that generate or modulate ASSRs.
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22
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D-Serine and a glycine transporter-1 inhibitor enhance social memory in rats. Psychopharmacology (Berl) 2010; 209:263-70. [PMID: 20198471 DOI: 10.1007/s00213-010-1794-y] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Accepted: 02/03/2010] [Indexed: 10/19/2022]
Abstract
RATIONALE Glutamatergic abnormalities are involved in the etiology of schizophrenia. Clinical evidence demonstrates that positive modulation of "glycine modulatory sites" on N-methyl-D: -aspartic acid (NMDA) receptors improve cognitive deficits as well as positive and negative symptoms in schizophrenic patients. OBJECTIVES In the present study, we investigated the effects of positive modulation of glycine sites on the NMDA receptor using an agonist of the glycine modulatory site, D: -serine, and a glycine transporter-1 inhibitor, (R)-(N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl])sarcosine (NFPS). In particular, we focused on the effects on cognitive functioning using social recognition test in rats. We then compared these effects with those of an atypical antipsychotic clozapine and a typical antipsychotic haloperidol. RESULTS Both D: -serine and NFPS significantly enhanced social memory in naïve rats, as did clozapine, while the typical antipsychotic haloperidol was ineffective. A noncompetitive NMDA receptor antagonist, MK-801, significantly impaired social memory, which was significantly attenuated by pretreatment with clozapine, but not with haloperidol. Likewise, NFPS significantly improved MK-801-disrupted cognition in the social recognition test. None of these drugs affected social interaction time. CONCLUSIONS The present results show that stimulation of the glycine modulatory sites on the NMDA receptor either directly with D: -serine or by blocking glycine transporter-1 enhances social memory and may be an effective approach for the treatment of the cognitive dysfunction observed in schizophrenic patients.
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Discovery of the imidazo[1,5-a][1,2,4]-triazolo[1,5-d][1,4]benzodiazepine scaffold as a novel, potent and selective GABAA α5 inverse agonist series. Bioorg Med Chem Lett 2009; 19:5746-52. [DOI: 10.1016/j.bmcl.2009.07.153] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 07/30/2009] [Accepted: 07/31/2009] [Indexed: 01/16/2023]
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24
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The discovery and unique pharmacological profile of RO4938581 and RO4882224 as potent and selective GABAA alpha5 inverse agonists for the treatment of cognitive dysfunction. Bioorg Med Chem Lett 2009; 19:5940-4. [PMID: 19762240 DOI: 10.1016/j.bmcl.2009.08.053] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 08/10/2009] [Accepted: 08/11/2009] [Indexed: 11/22/2022]
Abstract
Lead optimisation of the imidazo[1,5-a][1,2,4]-triazolo[1,5-d][1,4]benzodiazepine class led to the identification of two clinical leads [RO4882224 (11) and RO4938581 (44)] functioning as novel potent and selective GABAA alpha5 inverse agonists. The unique pharmacological profiles and optimal pharmacokinetic profiles resulted in in vivo activity in selected cognition models.
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25
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Dorsal hippocampal progesterone infusions enhance object recognition in young female mice. Pharmacol Biochem Behav 2009; 93:177-82. [PMID: 19477194 DOI: 10.1016/j.pbb.2009.05.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 05/12/2009] [Accepted: 05/17/2009] [Indexed: 11/21/2022]
Abstract
The effects of progesterone on memory are not nearly as well studied as the effects of estrogens. Although progesterone can reportedly enhance spatial and/or object recognition in female rodents when given immediately after training, previous studies have injected progesterone systemically, and therefore, the brain regions mediating this enhancement are not clear. As such, this study was designed to determine the role of the dorsal hippocampus in mediating the beneficial effect of progesterone on object recognition. Young ovariectomized C57BL/6 mice were trained in a hippocampal-dependent object recognition task utilizing two identical objects, and then immediately or 2 h afterwards, received bilateral dorsal hippocampal infusions of vehicle or 0.01, 0.1, or 1.0 microg/microl water-soluble progesterone. Forty-eight hours later, object recognition memory was tested using a previously explored object and a novel object. Relative to the vehicle group, memory for the familiar object was enhanced in all groups receiving immediate infusions of progesterone. Progesterone infusion delayed 2 h after training did not affect object recognition. These data suggest that the dorsal hippocampus may play a critical role in progesterone-induced enhancement of object recognition.
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Singer P, Yee BK, Feldon J, Iwasato T, Itohara S, Grampp T, Prenosil G, Benke D, Möhler H, Boison D. Altered mnemonic functions and resistance to N-METHYL-d-Aspartate receptor antagonism by forebrain conditional knockout of glycine transporter 1. Neuroscience 2009; 161:635-54. [PMID: 19332109 DOI: 10.1016/j.neuroscience.2009.03.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 03/17/2009] [Accepted: 03/22/2009] [Indexed: 01/15/2023]
Abstract
Converging evidence from pharmacological and molecular studies has led to the suggestion that inhibition of glycine transporter 1 (GlyT1) constitutes an effective means to boost N-methyl-d-aspartate receptor (NMDAR) activity by increasing the extra-cellular concentration of glycine in the vicinity of glutamatergic synapses. However, the precise extent and limitation of this approach to alter cognitive function, and therefore its potential as a treatment strategy against psychiatric conditions marked by cognitive impairments, remain to be fully examined. Here, we generated mutant mice lacking GlyT1 in the entire forebrain including neurons and glia. This conditional knockout system allows a more precise examination of GlyT1 downregulation in the brain on behavior and cognition. The mutation was highly effective in attenuating the motor-stimulating effect of acute NMDAR blockade by phencyclidine, although no appreciable elevation in NMDAR-mediated excitatory postsynaptic currents (EPSC) was observed in the hippocampus. Enhanced cognitive performance was observed in spatial working memory and object recognition memory while spatial reference memory and associative learning remained unaltered. These findings provide further credence for the potential cognitive enhancing effects of brain GlyT1 inhibition. At the same time, they indicated potential phenotypic differences when compared with other constitutive and conditional GlyT1 knockout lines, and highlighted the possibility of a functional divergence between the neuronal and glia subpopulations of GlyT1 in the regulation of learning and memory processes. The relevance of this distinction to the design of future GlyT1 blockers as therapeutic tools in the treatment of cognitive disorders remains to be further investigated.
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Affiliation(s)
- P Singer
- Laboratory of Behavioral Neurobiology, Federal Institute of Technology (ETH) Zurich, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland
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Affective and cognitive effects of global deletion of alpha3-containing gamma-aminobutyric acid-A receptors. Behav Pharmacol 2008; 19:582-96. [PMID: 18690113 DOI: 10.1097/fbp.0b013e32830dc0c7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Gamma-aminobutyric acid (GABA)A receptors characterized by the presence of the alpha3 subunit are the major GABAA receptor subtype expressed in brain stem monoaminergic nuclei. These alpha3-GABAA receptors are therefore in a unique position to regulate monoaminergic functions. To characterize the functional properties of alpha3-GABAA receptors, we present a preliminary assessment of the expression of affective and cognitive behaviour in male mice with a targeted deletion of the Gabra3 gene encoding the alpha3 subunit [alpha3 knockout (KO) mice] on a C57BL/6Jx129X1/SvJ F1 hybrid genetic background. The alpha3 KO mice did not exhibit any gross change of anxiety-like behaviour or spontaneous locomotor behaviour. In the Porsolt forced swim test for potential antidepressant activity, alpha3 KO mice exhibited reduced floating and enhanced swimming behaviour relative to wild-type controls. Performance on a two-choice sucrose preference test, however, revealed no evidence for an increase in sucrose preference in the alpha3 KO mice that would have substantiated a potential phenotype for depression-related behaviour. In contrast, a suggestion of an enhanced negative contrast effect was revealed in a one-bottle sucrose consumption test across different sucrose concentrations. These affective phenotypes were accompanied by alterations in the balance between conditioned responding to the discrete conditioned stimulus and to the context, and a suggestion of faster extinction, in the Pavlovian conditioned freezing paradigm. Spatial learning in the water maze reference memory test, however, was largely unchanged in the alpha3 KO mice, except for a trend of preservation during reversal learning. The novel phenotypes following global deletion of the GABAA receptor alpha3 subunit identified here provided relevant insights, in addition to our earlier study, into the potential behavioural relevance of this specific receptor subtypes in the modulation of both affective and cognitive functions.
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28
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Ennaceur A, Michalikova S, Chazot PL. Do rats really express neophobia towards novel objects? Experimental evidence from exposure to novelty and to an object recognition task in an open space and an enclosed space. Behav Brain Res 2008; 197:417-34. [PMID: 18992282 DOI: 10.1016/j.bbr.2008.10.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2008] [Revised: 09/30/2008] [Accepted: 10/04/2008] [Indexed: 02/02/2023]
Abstract
Three set of experiments were performed in an enclosed space (open-field) and in an open space (elevated platform). The surface of the open-field and the elevated platform were divided in nine equal squares. Rats were exposed (without previous habituation) in a unique session (experiment 1) or three consecutive sessions (experiment 2) either to an open-field (enclosed space) or to an elevated platform (open space) with and without an object on the centre of the field. In experiment 3, rats were exposed (without previous habituation) either to an enclosed or an open space on five consecutive sessions, one session a day. They were tested in an object recognition test in sessions 1, 3 and 5. In sessions 2 and 4, no objects were present. In experiment 1, we recorded the latency, frequency and duration of entries into different areas of the field. In experiment 3, we recorded the latency, frequency and duration of contacts with objects in addition to entries into different areas of the field. The first experiment demonstrates that rats exposed for the first time to an enclosed or an open space do not express neophobia toward novel objects in the absence of walls that surround an open-field. They crossed frequently into and spent more time in areas occupied with an object than in unoccupied areas. After two sessions of habituation to an empty open space or an empty enclosed space, the latency of first approach to a novel object is reduced while the frequency and duration of approaches are increased. The third experiment on object recognition confirmed that rats do not avoid novel objects; they made frequent visit and spent more time in the corner of the field occupied with an object than in empty corners. Recording of crossings provided detailed information about the patterns of exploratory behavior of rats but failed to reveal discrimination between novel and familiar objects which was evident in both open and enclosed space with recording of contacts with objects on the fifth exposure.
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Affiliation(s)
- A Ennaceur
- University of Sunderland, Sunderland Pharmacy School, Wharncliffe Street, Sunderland, SR1 3SD, UK.
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Manahan-Vaughan D, Wildförster V, Thomsen C. Rescue of hippocampal LTP and learning deficits in a rat model of psychosis by inhibition of glycine transporter-1 (GlyT1). Eur J Neurosci 2008; 28:1342-50. [DOI: 10.1111/j.1460-9568.2008.06433.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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