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Effects of T-type calcium channel blockers on cocaine-induced hyperlocomotion and thalamocortical GABAergic abnormalities in mice. Psychopharmacology (Berl) 2010; 212:205-14. [PMID: 20652540 DOI: 10.1007/s00213-010-1947-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 06/27/2010] [Indexed: 10/19/2022]
Abstract
RATIONALE Repetitive cocaine exposure has been shown to induce GABAergic thalamic alterations. Given the key role of T-type (Ca(V)3) calcium channels in thalamocortical physiology, the direct involvement of these calcium channels in cocaine-mediated effects needs to be further explored. OBJECTIVE The objective of this study was to investigate the effect of T-type calcium channel blockers on acute and repetitive cocaine administration that mediates thalamocortical alterations in mice using three different T-type blockers: 2-octanol, nickel, and mibefradil. METHODS During in vitro experiments, whole-cell patch-clamp recordings were conducted in ventrobasal (VB) thalamic neurons from mice treated with acute repetitive cocaine administration (3 x 15 mg/kg, i.p., 1 h apart), under bath application of mibefradil (10 μM), 2-octanol (50 μM), or nickel (200 μM). After systemic administration of T-type calcium channel blockers, we evaluated locomotor activity and also recorded GABAergic neurotransmission onto VB neurons in vitro. RESULTS Bath-applied mibefradil, 2-octanol, or nickel significantly reduced both GABAergic neurotransmission and T-type currents of VB neurons in cocaine-treated mice. In vivo i.p. pre-administration of either mibefradil (20 mg/kg and 5 mg/kg) or 2-octanol (0.5 mg/kg and 0.07 mg/kg) significantly reduced GABAergic mini frequencies onto VB neurons. Moreover, both mibefradil and 2-octanol were able to decrease cocaine-induced hyperlocomotion. CONCLUSION The results shown in this study strongly suggest that T-type calcium channels play a key role in cocaine-mediated GABAergic thalamocortical alterations, and further propose T-type channel blockers as potential targets for future pharmacological strategies aimed at treating cocaine's deleterious effects on physiology and behavior.
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Govindaiah G, Wang T, Gillette MU, Crandall SR, Cox CL. Regulation of inhibitory synapses by presynaptic D₄ dopamine receptors in thalamus. J Neurophysiol 2010; 104:2757-65. [PMID: 20884758 DOI: 10.1152/jn.00361.2010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dopamine (DA) receptors are the principal targets of drugs used in the treatment of schizophrenia. Among the five DA receptor subtypes, the D(4) subtype is of particular interest because of the relatively high affinity of the atypical neuropleptic clozapine for D(4) compared with D(2) receptors. GABA-containing neurons in the thalamic reticular nucleus (TRN) and globus pallidus (GP) express D(4) receptors. TRN neurons receive GABAergic afferents from globus pallidus (GP), substantia nigra pars reticulata (SNr), and basal forebrain as well as neighboring TRN neuron collaterals. In addition, TRN receives dopaminergic innervations from substantia nigra pars compacta (SNc); however, the role of D(4) receptors in neuronal signaling at inhibitory synapses is unknown. Using whole cell recordings from in vitro pallido-thalamic slices, we demonstrate that DA selectively suppresses GABA(A) receptor-mediated inhibitory postsynaptic currents (IPSCs) evoked by GP stimulation. The D(2)-like receptor (D(2,3,4)) agonist, quinpirole, and selective D(4) receptor agonist, PD168077, mimicked the actions of DA. The suppressive actions of DA and its agonists were associated with alterations in paired pulse ratio and a decrease in the frequency of miniature IPSCs, suggesting a presynaptic site of action. GABA(A) receptor agonist, muscimol, induced postsynaptic currents in TRN neurons were unaltered by DA or quinpirole, consistent with the presynaptic site of action. Finally, DA agonists did not alter intra-TRN inhibitory signaling. Our data demonstrate that the activation of presynaptic D(4) receptors regulates GABA release from GP efferents but not TRN collaterals. This novel and selective action of D(4) receptor activation on GP-mediated inhibition may provide insight to potential functional significance of atypical antipsychotic agents. These findings suggest a potential heightened TRN neuron activity in certain neurological conditions, such as schizophrenia and attention deficit hyperactive disorders.
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Affiliation(s)
- Gubbi Govindaiah
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, IL 61801, USA.
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Kristiansen LV, Bakir B, Haroutunian V, Meador-Woodruff JH. Expression of the NR2B-NMDA receptor trafficking complex in prefrontal cortex from a group of elderly patients with schizophrenia. Schizophr Res 2010; 119:198-209. [PMID: 20347576 PMCID: PMC2868940 DOI: 10.1016/j.schres.2010.02.1069] [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] [Received: 09/24/2009] [Revised: 02/23/2010] [Accepted: 02/25/2010] [Indexed: 10/19/2022]
Abstract
Dysregulated glutamate neurotransmission has been implicated in the pathophysiology of schizophrenia. In particular, hypofunction of the NMDA glutamate receptor has been proposed to play an important role in mediating cognitive deficits in patients. The two NMDA receptor subunits, NR2A and NR2B, are distinctly regulated during development and are associated with different intracellular pathways and functions, which suggest that these receptors play separate roles in the control of higher cognitive functions such as learning and memory. Trafficking of the NR2B subunit-containing receptor is regulated by a microtubule-associated trafficking complex consisting of the KIF17, APBA1, CASK, and mLin7 proteins. Several studies have demonstrated an integrated functional regulation of this trafficking complex with NR2B receptor subunit expression, which in turn has been linked to higher cognitive functions. In the present work, we investigated whether expression of this NR2B-associated trafficking complex might be abnormal in schizophrenia. We analyzed the expression of KIF17, APBA1, CASK, mLin7A and mLin7C in postmortem brain from patients with schizophrenia a comparison group. Analysis of transcripts for all of these proteins revealed particularly prominent expression in cortical layer III and layer IV, which overlapped with NR2B but not NR2A transcripts. We found altered expression of transcripts for the CASK, ABPA1, and mLin7 molecules and the CASK, mLin7 proteins, suggesting that NR2B-containing NMDA receptor transport could be selectively compromised in schizophrenia, and that these changes likely involve altered NR2B function in a subset of cortical neurons.
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Affiliation(s)
- LV Kristiansen
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
,Corresponding author: European Science Foundation, 1 Quai Lezai-Marnésia 67080 Strasbourg Cedex, France, Telephone, +33 658631018, Fax: +33 388 370532,
| | - B Bakir
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
| | - V Haroutunian
- Department of Psychiatry, Mount Sinai School of Medicine, Bronx VA Medical Center, Bronx, NY 10468, USA.
| | - JH Meador-Woodruff
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
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54
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Behrendt RP. Contribution of hippocampal region CA3 to consciousness and schizophrenic hallucinations. Neurosci Biobehav Rev 2009; 34:1121-36. [PMID: 20034516 DOI: 10.1016/j.neubiorev.2009.12.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Revised: 11/18/2009] [Accepted: 12/15/2009] [Indexed: 01/31/2023]
Abstract
Recent advances in understanding hippocampal information processing offer new vistas on the mind-body and binding problems. Information encoded by the autoassociation network of cornu ammonis 3 (CA3) situates landmarks and objects within an allocentric framework of space and time. Guiding locomotion across the spatial environment, and generally organizing behaviour that transcends space and time, the hippocampus creates phenomenal space and time themselves, thus laying the foundations for conscious awareness. It is argued that conscious experience describes/symbolizes the informational content of self-organizing activity patterns in CA3. Imagery, conscious perception or hallucinations do not in themselves affect the physical trajectory of behaviour but are evidence for patterns of neuronal activity that, acting via the medial prefrontal cortex, modulate action dispositions and influence prefrontal top-down attentional control of sensory processing and thus subsequent event memory formation. Evidence for GABAergic deficit and pyramidal cell hyperexcitability in CA3 in patients with schizophrenia is consistent with the notion that binding, by the CA3 network, of cortical modules representing weakly related sensory representations underlies hallucinations in this disorder.
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55
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Zhang Y, Llinas RR, Lisman JE. Inhibition of NMDARs in the Nucleus Reticularis of the Thalamus Produces Delta Frequency Bursting. Front Neural Circuits 2009; 3:20. [PMID: 20057928 PMCID: PMC2802545 DOI: 10.3389/neuro.04.020.2009] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 10/23/2009] [Indexed: 01/18/2023] Open
Abstract
Injection of NMDAR antagonist into the thalamus can produce delta frequency EEG oscillations in the thalamocortical system. It is surprising that an antagonist of an excitatory neurotransmitter should trigger such activity, and the mechanism is unknown. One hypothesis is that the antagonist blocks excitation of GABAergic cells, thus producing disinhibition. To test this hypothesis, we investigated the effect of NMDAR antagonist (APV) on cells of the nucleus reticularis (nRT) in rat brain slices, a thalamic nucleus that can serve as a pacemaker for thalamocortical delta oscillations and that is composed entirely of GABAergic neurons. We found, unexpectedly, that nRT cells are hyperpolarized by APV. This occurs because these cells have an unusual form of NMDAR (probably NR2C) that contributes inward current at resting potential in response to ambient glutamate. The hyperpolarization produced by APV is sufficient to deinactivate T-type calcium channels, and these trigger rhythmic bursting at delta frequency. The APV-induced delta frequency bursting is abolished by dopamine D2 receptor antagonist, indicating that dopamine and NMDAR antagonist work synergistically to stimulate delta frequency bursting. Our results have significant implications concerning the electrophysiological basis of schizophrenia and bring together the NMDAR hypofunction, dopamine, and GABA theories of the disease. Our results suggest that NMDAR hypofunction and dopamine work synergistically on the GABAergic cells of the nRT to generate the delta frequency EEG oscillations, a thalamocortical dysrhythmia (TCD) in the awake state that is an established abnormality in schizophrenia.
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Affiliation(s)
- Yuchun Zhang
- Department of Biology and Volen Center for Complex Systems, Brandeis UniversityWaltham, MA, USA
| | - Rodolfo R. Llinas
- Department of Physiology and Neuroscience, New York University School of MedicineNew York, NY, USA
| | - John E. Lisman
- Department of Biology and Volen Center for Complex Systems, Brandeis UniversityWaltham, MA, USA
- *Correspondence: John E. Lisman, Department of Biology and Volen Center for Complex Systems, Brandeis University, MS 008, 415 South Street, Waltham, MA 02454, USA. e-mail:
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56
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Pakkenberg B, Scheel-Krüger J, Kristiansen LV. Schizophrenia; from structure to function with special focus on the mediodorsal thalamic prefrontal loop. Acta Psychiatr Scand 2009; 120:345-54. [PMID: 19807715 DOI: 10.1111/j.1600-0447.2009.01447.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To describe structural and biochemical evidence from postmortem brains that implicates the reciprocal connections between the mediodorsal thalamic nucleus and the prefrontal cortex in cognitive symptoms of schizophrenia. METHOD The estimation of the regional volumes and cell numbers was obtained using stereological methods. The biochemical analyses of molecular expression in postmortem brain involve quantitative measurement of transcripts and proteins by in-situ (RNA) or Western blot/autoradiography in brains from patients with schizophrenia and comparison subjects. RESULTS Stereological studies in postmortem brain from patients with schizophrenia have reported divergent and often opposing findings in the total number of neurons and volume of the mediodorsal (MD) thalamic nucleus, and to a lesser degree in its reciprocally associated areas of the prefrontal cortex. Similarly, quantitative molecular postmortem studies have found large inter-subject and between-study variance at both the transcript and protein levels for receptors and their interacting molecules of several neurotransmitter systems in these interconnected anatomical regions. Combined, large variation in stereological and molecular studies indicates a complex and heterogeneous involvement of the MD thalamic-prefrontal loop in schizophrenia. CONCLUSION Based on a considerable heterogeneity in patients suffering from schizophrenia, large variation in postmortem studies, including stereological and molecular postmortem studies of the MD thalamus and frontal cortex, might be expected and may in fact partly help to explain the variable endophenotypic traits associated with this severe psychiatric illness.
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Affiliation(s)
- B Pakkenberg
- Research Laboratory for Stereology and Neuroscience, Bispebjerg University Hospital, Copenhagen, Denmark.
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57
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Dome P, Lazary J, Kalapos MP, Rihmer Z. Smoking, nicotine and neuropsychiatric disorders. Neurosci Biobehav Rev 2009; 34:295-342. [PMID: 19665479 DOI: 10.1016/j.neubiorev.2009.07.013] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/23/2009] [Accepted: 07/30/2009] [Indexed: 12/20/2022]
Abstract
Tobacco smoking is an extremely addictive and harmful form of nicotine (NIC) consumption, but unfortunately also the most prevalent. Although disproportionately high frequencies of smoking and its health consequences among psychiatric patients are widely known, the neurobiological background of this epidemiological association is still obscure. The diverse neuroactive effects of NIC and some other major tobacco smoke constituents in the central nervous system may underlie this association. This present paper summarizes the pharmacology of NIC and its receptors (nAChR) based on a systematic review of the literature. The role of the brain's reward system(s) in NIC addiction and the results of functional and structural neuroimaging studies on smoking-related states and behaviors (i.e. dependence, craving, withdrawal) are also discussed. In addition, the epidemiological, neurobiological, and genetic aspects of smoking in several specific neuropsychiatric disorders are reviewed and the clinical relevance of smoking in these disease states addressed.
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Affiliation(s)
- Peter Dome
- Department of Clinical and Theoretical Mental Health, Kutvolgyi Clinical Center, Semmelweis University, Faculty of Medicine, Kutvolgyi ut 4, 1125 Budapest, Hungary.
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58
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Hauser TA, Kucinski A, Jordan KG, Gatto GJ, Wersinger SR, Hesse RA, Stachowiak EK, Stachowiak MK, Papke RL, Lippiello PM, Bencherif M. TC-5619: an alpha7 neuronal nicotinic receptor-selective agonist that demonstrates efficacy in animal models of the positive and negative symptoms and cognitive dysfunction of schizophrenia. Biochem Pharmacol 2009; 78:803-12. [PMID: 19482012 DOI: 10.1016/j.bcp.2009.05.030] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 05/19/2009] [Accepted: 05/21/2009] [Indexed: 02/07/2023]
Abstract
A growing body of evidence suggests that the alpha7 neuronal nicotinic receptor (NNR) subtype is an important target for the development of novel therapies to treat schizophrenia, offering the possibility to address not only the positive but also the cognitive and negative symptoms associated with the disease. In order to probe the relationship of alpha7 function to relevant behavioral correlates we employed TC-5619, a novel selective agonist for the alpha7 NNR subtype. TC-5619 binds with very high affinity to the alpha7 subtype and is a potent full agonist. TC-5619 has little or no activity at other nicotinic receptors, including the alpha4beta2, ganglionic (alpha3beta4) and muscle subtypes. The transgenic th(tk-)/th(tk-) mouse model that reflects many of the developmental, anatomical, and multi-transmitter biochemical aspects of schizophrenia was used to assess the antipsychotic effects of TC-5619. In these mice TC-5619 acted both alone and synergistically with the antipsychotic clozapine to correct impaired pre-pulse inhibition (PPI) and social behavior which model positive and negative symptoms, respectively. Antipsychotic and cognitive effects of TC-5619 were also assessed in rats. Similar to the results in the transgenic mice, TC-5619 significantly reversed apomorphine-induced PPI deficits. In a novel object recognition paradigm in rats TC-5619 demonstrated long-lasting enhancement of memory over a wide dose range. These results suggest that alpha7-selective agonists such as TC-5619, either alone or in combination with antipsychotics, could offer a new approach to treating the constellation of symptoms associated with schizophrenia, including cognitive dysfunction.
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MESH Headings
- Animals
- Antipsychotic Agents/pharmacology
- Antipsychotic Agents/therapeutic use
- Behavior, Animal/drug effects
- Benzofurans/pharmacology
- Benzofurans/therapeutic use
- Clozapine/pharmacology
- Clozapine/therapeutic use
- Cognition Disorders/drug therapy
- Cognition Disorders/metabolism
- Cognition Disorders/psychology
- Exploratory Behavior/drug effects
- Female
- Male
- Maze Learning/drug effects
- Mice
- Mice, Transgenic
- Neurons/metabolism
- Nicotinic Agonists/pharmacology
- Nicotinic Agonists/therapeutic use
- Promoter Regions, Genetic
- Quinuclidines/pharmacology
- Quinuclidines/therapeutic use
- Rats
- Rats, Sprague-Dawley
- Receptor, Fibroblast Growth Factor, Type 1/biosynthesis
- Receptor, Fibroblast Growth Factor, Type 1/genetics
- Receptors, Nicotinic/physiology
- Reflex, Startle/drug effects
- Schizophrenia/drug therapy
- Schizophrenia/metabolism
- Schizophrenic Psychology
- Social Behavior
- Tyrosine 3-Monooxygenase/genetics
- alpha7 Nicotinic Acetylcholine Receptor
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Affiliation(s)
- T A Hauser
- Preclinical Research, Targacept, Inc, Winston-Salem, NC 27101, USA.
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59
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Pan PY, Tian JH, Sheng ZH. Snapin facilitates the synchronization of synaptic vesicle fusion. Neuron 2009; 61:412-24. [PMID: 19217378 PMCID: PMC2656773 DOI: 10.1016/j.neuron.2008.12.029] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2008] [Revised: 12/23/2008] [Accepted: 12/29/2008] [Indexed: 12/25/2022]
Abstract
Synaptic vesicle (SV) fusion is a fine-tuned process requiring a concert of fusion machineries. Using cortical neurons from snapin-deficient mice, we reveal a role for Snapin in facilitating synchronous release. In addition to reduced frequency of miniature excitatory postsynaptic currents (mini-EPSCs) and smaller release-ready vesicle pool (RRP) size, snapin deficiency results in EPSCs with multiple peaks and increased rise and decay times, reflecting "desynchronized" SV fusion. These defects impair both synaptic precision and efficacy during sustained neurotransmission. Transient expression of Snapin not only rescues the slowed kinetics of EPSCs, but also further accelerates the rate found in wild-type neurons. Furthermore, expression of Snapin-C66A, a dimerization-defective mutant with impaired interactions with SNAP-25 and Synaptotagmin, reduces the RRP size but exhibits less effect on synchronized fusion. Our studies provide mechanistic insights into a dual role of Snapin in enhancing the efficacy of SV priming and in fine-tuning synchronous SV fusion.
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Affiliation(s)
- Ping-Yue Pan
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 35, Room 3B203, 35 Convent Drive, Bethesda, Maryland 20892-3701, USA
- Department of Neurobiology, School of Medicine, Shanghai Jiaotong University, Shanghai 200025, China
| | - Jin-Hua Tian
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 35, Room 3B203, 35 Convent Drive, Bethesda, Maryland 20892-3701, USA
| | - Zu-Hang Sheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 35, Room 3B203, 35 Convent Drive, Bethesda, Maryland 20892-3701, USA
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60
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Martínez-Granados B, Brotons O, Martínez-Bisbal MC, Celda B, Martí-Bonmati L, Aguilar EJ, González JC, Sanjuán J. Spectroscopic metabolomic abnormalities in the thalamus related to auditory hallucinations in patients with schizophrenia. Schizophr Res 2008; 104:13-22. [PMID: 18650068 DOI: 10.1016/j.schres.2008.05.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 02/25/2008] [Accepted: 05/25/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Previous studies have found neurochemical abnormalities in thalamic nuclei in patients with schizophrenia. These abnormalities have been associated with information processing deficiencies and symptom formation. There are no metabolic spectroscopy studies in patients with schizophrenia attending to auditory hallucinations. The aim of the present study is to explore metabolic Magnetic Resonance Spectroscopy (MRS) ratio differences in the thalamus between schizophrenic patients with and without auditory hallucinations and control subjects. METHODS MRS studies (MRI 1.5 T unit) were performed in 49 patients with schizophrenia (30 with auditory hallucinations and 19 without auditory hallucinations) and 37 controls. (1)H MRS imaging was used to acquire 2 transverse slices (TR/TE 2700/272 ms, region of interest 110 x 100 x 23 mm). In the quantitative analysis four elements of volume (9.2 x 9.2 x 23 x 4 mm), added into one spectrum representative of each thalamus, were chosen in the slice passing through the main body of the thalamus. The areas of metabolites were integrated with the jMRUI program. RESULTS The patients with schizophrenia had significantly lower bilateral NAA/Cho ratios when compared with healthy subjects. There was also a lower NAA/Cho ratio in the right thalamus in patients with auditory hallucinations compared to patients without auditory hallucinations and control subjects. Significant correlations were found between metabolic ratios and BPRS, PANSS and PSYRATS scores, age of onset of auditory hallucinations, and age of subjects. CONCLUSIONS Choline and NAA ratio abnormalities determined by thalamic spectroscopy may be related to the pathogenesis of auditory hallucinations in patients with schizophrenia.
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Affiliation(s)
- B Martínez-Granados
- Department of Physical Chemistry, University of Valencia, C/ Dr Moliner 50, 46100 Burjassot, Valencia, Spain.
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Mapping autism and schizophrenia onto the ontogenesis of social behaviour: A hierarchical-developmental rather than diametrical perspective. Behav Brain Sci 2008. [DOI: 10.1017/s0140525x08004238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractCo-morbidity of schizophrenia and autism is low because interpersonal concerns of schizophrenic patients presuppose developmental achievements that are absent in autism. Autism may arise if primary anxiety is not overcome at a key developmental stage by affective synchronisation between infant and caregiver. Schizophrenic patients will have learned to regulate primitive anxiety by affectively attuning to narrow social networks but remain highly vulnerable to exclusion from larger groups.
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Stroobants S, Leroy T, Eckhardt M, Aerts JM, Berckmans D, D'Hooge R. Early signs of neurolipidosis-related behavioural alterations in a murine model of metachromatic leukodystrophy. Behav Brain Res 2008; 189:306-16. [PMID: 18336930 DOI: 10.1016/j.bbr.2008.01.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 01/10/2008] [Accepted: 01/14/2008] [Indexed: 10/22/2022]
Abstract
Arylsulfatase A (ASA)-deficient mice represent an animal model for the lysosomal storage disorder metachromatic leukodystrophy (MLD). Although the model has been applied in pathophysiological and therapeutic studies, the behavioural phenotype of ASA(-/-) mice is only partially characterized, and the most decisive outcome measures for therapy evaluation only emerge beyond 1 year of age. Presently, ASA(-/-) mice and ASA(+/-) control mice were studied at 6 and 12 months of age on an extensive battery including tests of neuromotor ability, exploratory behaviour, and learning and memory. Overt signs of ataxia were not observed in 6-month-old ASA(-/-) mice, but quantitative gait analysis during open-field exploration revealed that ASA(-/-) mice displayed increased hind base width and increased stride lengths for all paws. Their covert motor incoordination was evident in a correlation analysis which unveiled decreased harmonisation of concurrent gait parameters. For example, while ASA(+/-) controls demonstrated substantial convergence of front and hind base width (r=0.54), these variables actually diverged in ASA(-/-) mice (r=-0.37). Furthermore, various behavioural observations indicated emotional alterations in ASA(-/-) mice. Six-month-old ASA(-/-) mice also showed decreased response rates in scheduled operant responding. The present findings could provide relevant behavioural outcome measures for further use of this murine MLD model in preclinical studies.
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Affiliation(s)
- Stijn Stroobants
- Laboratory of Biological Psychology, Department of Psychology, University of Leuven, Leuven, Belgium
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63
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Stone JM, Morrison PD, Pilowsky LS. Glutamate and dopamine dysregulation in schizophrenia--a synthesis and selective review. J Psychopharmacol 2007; 21:440-52. [PMID: 17259207 DOI: 10.1177/0269881106073126] [Citation(s) in RCA: 253] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The dopamine hypothesis of schizophrenia is the principal explanatory model of antipsychotic drug action. Recent discoveries extend our understanding of the neurochemistry of schizophrenia, with increasing evidence of dysfunction in glutamate and GABA as well as dopamine systems. In this review, we study the evidence for dopaminergic dysfunction in schizophrenia, drawing data from neurochemical imaging studies. We also review the NMDA receptor hypofunction hypothesis of schizophrenia as a supplementary explanatory model for the illness. We examine predictions made by the NMDA receptor hypofunction hypothesis and consider how they fit with current neurochemical findings in patients and animal models. We consider the case for glutamatergic excitotoxicity as a key process in the development and progression of schizophrenia, and suggest ways in which glutamate and dopamine dysregulation may interact in the condition.
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Affiliation(s)
- James M Stone
- King's College London Institute of Psychiatry, London, UK.
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