301
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Fatemi SH, Folsom TD, Reutiman TJ, Thuras PD. Expression of GABA(B) receptors is altered in brains of subjects with autism. CEREBELLUM (LONDON, ENGLAND) 2009; 8:64-9. [PMID: 19002745 PMCID: PMC2732344 DOI: 10.1007/s12311-008-0075-3] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Autism is a neurodevelopmental disorder that is often comorbid with seizures. Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in brain. GABA(B) receptors play an important role in maintaining excitatory-inhibitory balance in brain and alterations may lead to seizures. We compared levels of GABA(B) receptor subunits GABA(B) receptor 1 (GABBR1) and GABA(B) receptor 2 (GABBR2) in cerebellum, Brodmann's area 9 (BA9), and BA40 of subjects with autism and matched controls. Levels of GABBR1 were significantly decreased in BA9, BA40, and cerebellum, while GABBR2 was significantly reduced in the cerebellum. The presence of seizure disorder did not have a significant impact on the observed reductions in GABA(B) receptor subunit expression. Decreases in GABA(B) receptor subunits may help explain the presence of seizures that are often comorbid with autism, as well as cognitive difficulties prevalent in autism.
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Affiliation(s)
- S Hossein Fatemi
- Department of Psychiatry, Division of Neuroscience Research, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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302
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Yip J, Soghomonian JJ, Blatt GJ. Decreased GAD65 mRNA levels in select subpopulations of neurons in the cerebellar dentate nuclei in autism: an in situ hybridization study. Autism Res 2009; 2:50-9. [PMID: 19358307 PMCID: PMC2724747 DOI: 10.1002/aur.62] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The laterally positioned dentate nuclei lie in a key position in the cerebellum to receive input from Purkinje cells in the lateral cerebellar hemisphere participating in both motor and cognitive functions. Although neuropathology of the four cerebellar nuclei using Nissl staining has been qualitatively reported in children and adults with autism, surprisingly the dentate nuclei appeared less affected despite reported reductions in Purkinje cells in the posterolateral cerebellar hemisphere. To determine any underlying abnormalities in the critically important GABAergic system, the rate-limiting GABA synthesizing enzyme, glutamic acid decarboxylase (GAD) type 65 was measured via in situ hybridization histochemistry in dentate somata. GAD65 mRNA labeling revealed two distinct subpopulations of neurons in adult control and autism postmortem brains: small-sized cells (about 10-12 microm in diameter, presumed interneurons) and larger-sized neurons (about 18-20 microm in diameter, likely feedback to inferior olivary neurons). A mean 51% reduction in GAD65 mRNA levels was found in the larger labeled cells in the autistic group compared with the control group (P=0.009; independent t-test) but not in the smaller cell subpopulation. This suggests a disturbance in the intrinsic cerebellar circuitry in the autism group potentially interfering with the synchronous firing of inferior olivary neurons, and the timing of Purkinje cell firing and inputs to the dentate nuclei. Disturbances in critical neural substrates within these key circuits could disrupt afferents to motor and/or cognitive cerebral association areas in the autistic brain likely contributing to the marked behavioral consequences characteristic of autism.
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Affiliation(s)
- Jane Yip
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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303
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A population-based association study of glutamate decarboxylase 1 as a candidate gene for autism. J Neural Transm (Vienna) 2009; 116:381-8. [PMID: 19139806 DOI: 10.1007/s00702-008-0142-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Accepted: 10/06/2008] [Indexed: 10/21/2022]
Abstract
Linkage studies, genome-wide scans and screening of possible candidate genes suggest that chromosome 2q31 may harbour one or more susceptibility genes for autism. The glutamate decarboxylase gene 1 (GAD1) located within chromosome 2q31 encodes the enzyme, GAD67, catalyzing the production of gamma-aminobutyric acid (GABA) from glutamate. Numerous independent findings have suggested the GABAergic system to be involved in autism. The present study investigates a Danish population-based, case-control sample of 444 subjects with childhood autism and 444 controls. Nine single nucleotide polymorphisms (SNPs) comprising the GAD1 gene and the microsatellite marker D2S2381 were examined for association with autism. We found no association between childhood autism and any single marker or 2-5 marker haplotypes. However, a rare nine-marker haplotype was associated with childhood autism. We cannot exclude neither GAD1 as a susceptibility gene nor the possibility of another susceptibility gene for autism to be located on chromosome 2q31.
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304
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Abstract
AimTo assess serum Cu/Zn SOD (Superoxide Dismutase) concentration in autistic children and evaluate its possible relationship to GI Symptoms.Subjects and MethodsSerum from 50 autistic children (31 with chronic digestive disease (most with ileo-colonic lymphoid nodular hyperplasia (LNH) and inflammation of the colorectal, small bowel and/or stomach) and 19 autistic children without GI disease), and 29 non autistic controls (20 age matched non autistic children with no GI disease and 9 age matched non autistic children with GI disease) were tested for Cu/Zn SOD using ELISAs.ResultsSerum Cu/Zn SOD levels of autistic children were significantly lower than all non autistic controls (p < 0.0001). Serum Cu/Zn SOD of autistic children with severe GI disease was significantly lower than autistic children with no GI disease (p < 0.0001), non autistic children without GI disease (<0.0001) and non autistic children with GI disease (p = 0.0003).DiscussionThese results suggest an association between Cu/Zn SOD serum levels and autism, particularly autistic children with GI disease, and that the concentration of serum Cu/Zn SOD may be a useful biomarker for autistic children with severe GI disease.
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Affiliation(s)
- A.J. Russo
- Health Research Institute/Pfeiffer Treatment Center, 4575 Weaver Parkway, Warrenville, Illinois 60555, USA
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305
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Fatemi SH, Reutiman TJ, Folsom TD, Thuras PD. GABA(A) receptor downregulation in brains of subjects with autism. J Autism Dev Disord 2008; 39:223-30. [PMID: 18821008 DOI: 10.1007/s10803-008-0646-7] [Citation(s) in RCA: 314] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 06/27/2008] [Indexed: 11/28/2022]
Abstract
Gamma-aminobutyric acid A (GABA(A)) receptors are ligand-gated ion channels responsible for mediation of fast inhibitory action of GABA in the brain. Preliminary reports have demonstrated altered expression of GABA receptors in the brains of subjects with autism suggesting GABA/glutamate system dysregulation. We investigated the expression of four GABA(A) receptor subunits and observed significant reductions in GABRA1, GABRA2, GABRA3, and GABRB3 in parietal cortex (Brodmann's Area 40 (BA40)), while GABRA1 and GABRB3 were significantly altered in cerebellum, and GABRA1 was significantly altered in superior frontal cortex (BA9). The presence of seizure disorder did not have a significant impact on GABA(A) receptor subunit expression in the three brain areas. Our results demonstrate that GABA(A) receptors are reduced in three brain regions that have previously been implicated in the pathogenesis of autism, suggesting widespread GABAergic dysfunction in the brains of subjects with autism.
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Affiliation(s)
- S Hossein Fatemi
- Department of Psychiatry, University of Minnesota, Minneapolis, MN 55455, USA.
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306
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Walker MA. Treatment of autism spectrum disorders: neurotransmitter signaling pathways involved in motivation and reward as therapeutic targets. Expert Opin Ther Targets 2008; 12:949-67. [PMID: 18620518 DOI: 10.1517/14728222.12.8.949] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND There is a growing body of literature describing the etiology of autism spectrum disorders (ASD). Some of the targets suggested belong to neurochemical transmitter pathways implicated in the behavior and motivation reward pathway. OBJECTIVE To examine data linking potential targets to ASD and the feasibility of developing drugs targeting these pathways. While the inhibitors are mostly being developed for other indications, it is beneficial to examine them to determine the responsiveness of the targets to small-molecule modulation. METHODS A search in Medline and Scifinder for articles concerning relevant targets in the context of ASD and their relation to the reward signaling pathway. RESULTS There is evidence suggesting that behaviors controlled by these targets are related to behaviors exhibited by individuals with ASD. The targets appear to be involved in neurotransmitter pathways controlling motivation and reward, further implicating this system in ASD. Sufficient research has been conducted to identify lead compounds for discovering agents for treatment of ASD.
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Affiliation(s)
- Michael A Walker
- Bristol-Myers Squibb Co., Medicinal Chemistry, Research and Development, Wallingford, CT, USA.
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307
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Glutamate alteration of glutamic acid decarboxylase (GAD) in GABAergic neurons: The role of cysteine proteases. Exp Neurol 2008; 213:145-53. [DOI: 10.1016/j.expneurol.2008.05.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Revised: 05/02/2008] [Accepted: 05/17/2008] [Indexed: 11/19/2022]
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308
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Intersubjectivity, affective neuroscience, and the neurobiology of autistic spectrum disorders: a systematic review. Keio J Med 2008; 57:15-36. [PMID: 18382122 DOI: 10.2302/kjm.57.15] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Intersubjectivity is an approach to the study of social interaction viewed from a perspective which rejects the view that reducing any such analysis to study at the level of the individual is adequate to address the issues of social functioning. It also stresses the view that social processes cannot be reduced to cognitive ones - most of the important questions in the study of developmental psychopathology deal with issues which have commonality with many other species and are patent well before the ontological emergence of 'cognitive' abilities. In this paper we review the evidence in this area, and discuss a range of issues relevant to autistic spectrum disorders. We focus in particular on social interaction; the role of the Intrinsic Motive Formation and recent work on mirror neurons in autism; genetic and teratogenic factors in the genesis of autism; and the role of a number of biological factors in pathogenesis - tryptophan; vitamin B12; sterol metabolism; glutamate and GABA; and the Fragile-X expansion.
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309
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Fatemi SH. The hyperglutamatergic hypothesis of autism. Prog Neuropsychopharmacol Biol Psychiatry 2008; 32:911, author reply 912-3. [PMID: 18160196 DOI: 10.1016/j.pnpbp.2007.11.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Accepted: 11/04/2007] [Indexed: 10/22/2022]
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310
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Garbett K, Ebert PJ, Mitchell A, Lintas C, Manzi B, Mirnics K, Persico AM. Immune transcriptome alterations in the temporal cortex of subjects with autism. Neurobiol Dis 2008; 30:303-311. [PMID: 18378158 DOI: 10.1016/j.nbd.2008.01.012] [Citation(s) in RCA: 278] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 01/23/2008] [Accepted: 01/29/2008] [Indexed: 12/21/2022] Open
Abstract
Autism is a severe disorder that involves both genetic and environmental factors. Expression profiling of the superior temporal gyrus of six autistic subjects and matched controls revealed increased transcript levels of many immune system-related genes. We also noticed changes in transcripts related to cell communication, differentiation, cell cycle regulation and chaperone systems. Critical expression changes were confirmed by qPCR (BCL6, CHI3L1, CYR61, IFI16, IFITM3, MAP2K3, PTDSR, RFX4, SPP1, RELN, NOTCH2, RIT1, SFN, GADD45B, HSPA6, HSPB8 and SERPINH1). Overall, these expression patterns appear to be more associated with the late recovery phase of autoimmune brain disorders, than with the innate immune response characteristic of neurodegenerative diseases. Moreover, a variance-based analysis revealed much greater transcript variability in brains from autistic subjects compared to the control group, suggesting that these genes may represent autism susceptibility genes and should be assessed in follow-up genetic studies.
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Affiliation(s)
| | - Philip J Ebert
- Department of Psychiatry, Vanderbilt University, Nashville, USA
| | - Amanda Mitchell
- Department of Psychiatry, Vanderbilt University, Nashville, USA
| | - Carla Lintas
- Laboratory of Molecular Psychiatry and Neurogenetics, University "Campus Bio-Medico", Rome, Italy; Laboratory of Molecular Psychiatry and Psychiatric Genetics, Department of Experimental Neurosciences, I.R.C.C.S. "Fondazione Santa Lucia", Rome, Italy
| | - Barbara Manzi
- Department of Child Neuropsychiatry, University "Tor Vergata", Rome, Italy
| | - Károly Mirnics
- Department of Psychiatry, Vanderbilt University, Nashville, USA; Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, USA.
| | - Antonio M Persico
- Laboratory of Molecular Psychiatry and Neurogenetics, University "Campus Bio-Medico", Rome, Italy; Laboratory of Molecular Psychiatry and Psychiatric Genetics, Department of Experimental Neurosciences, I.R.C.C.S. "Fondazione Santa Lucia", Rome, Italy.
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311
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Bransfield RC, Wulfman JS, Harvey WT, Usman AI. The association between tick-borne infections, Lyme borreliosis and autism spectrum disorders. Med Hypotheses 2008; 70:967-74. [DOI: 10.1016/j.mehy.2007.09.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2007] [Accepted: 09/07/2007] [Indexed: 11/17/2022]
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312
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IncreasedGAD67 mRNA expression in cerebellar interneurons in autism: Implications for Purkinje cell dysfunction. J Neurosci Res 2008; 86:525-30. [DOI: 10.1002/jnr.21520] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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313
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Orekhova EV, Stroganova TA, Nygren G, Tsetlin MM, Posikera IN, Gillberg C, Elam M. Excess of high frequency electroencephalogram oscillations in boys with autism. Biol Psychiatry 2007; 62:1022-9. [PMID: 17543897 DOI: 10.1016/j.biopsych.2006.12.029] [Citation(s) in RCA: 192] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 12/05/2006] [Accepted: 12/20/2006] [Indexed: 11/24/2022]
Abstract
BACKGROUND An elevated excitation/inhibition ratio has been suggested as one mechanism underpinning autism. An imbalance between cortical excitation and inhibition may manifest itself in electroencephalogram (EEG) abnormalities in the high frequency range. The aim of this study was to investigate whether beta and gamma range EEG abnormalities are characteristic for young boys with autism (BWA). METHODS EEG was recorded during sustained visual attention in two independent samples of BWA from Moscow and Gothenburg, aged 3 to 8 years, and in age matched typically developing boys (TDB). High frequency EEG spectral power was analyzed. RESULTS In both samples, BWA demonstrated a pathological increase of gamma (24.4-44.0 Hz) activity at the electrode locations distant from the sources of myogenic artefacts. In both samples, the amount of gamma activity correlated positively with degree of developmental delay in BWA. CONCLUSIONS The excess of high frequency oscillations may reflect imbalance in the excitation-inhibition homeostasis in the cortex. Given the important role of high frequency EEG rhythms for perceptual and cognitive processes, early and probably genetically determined abnormalities in the neuronal mechanisms generating high frequency EEG rhythms may contribute to development of the disorder. Further studies are needed to investigate the specificity of the findings for autism.
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Affiliation(s)
- Elena V Orekhova
- Department of Clinical Neurophysiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
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314
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D'Hulst C, Kooy RF. The GABAA receptor: a novel target for treatment of fragile X? Trends Neurosci 2007; 30:425-31. [PMID: 17590448 DOI: 10.1016/j.tins.2007.06.003] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 05/11/2007] [Accepted: 06/06/2007] [Indexed: 11/29/2022]
Abstract
GABA(A) receptors are the major inhibitory neurotransmitter receptors in the mammalian brain, implicated in anxiety, depression, epilepsy, insomnia, and learning and memory. Here, we present several lines of evidence for involvement of the GABAergic system, and in particular the GABA(A) receptor-mediated function, in fragile X syndrome, the most common form of inherited mental retardation. We argue that an altered expression of the GABA(A) receptor has neurophysiologic and functional consequences that might relate to the behavioural and neurological phenotype associated with fragile X syndrome. Interestingly, some neuropsychiatric disorders, such as anxiety, epilepsy and sleep disorders, are effectively treated with therapeutic agents that act on the GABA(A) receptor. Therefore, the GABA(A) receptor might be a novel therapeutic target for fragile X syndrome.
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Affiliation(s)
- Charlotte D'Hulst
- Department of Medical Genetics, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium.
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315
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Tommerdahl M, Tannan V, Cascio CJ, Baranek GT, Whitsel BL. Vibrotactile adaptation fails to enhance spatial localization in adults with autism. Brain Res 2007; 1154:116-23. [PMID: 17498672 PMCID: PMC1987714 DOI: 10.1016/j.brainres.2007.04.032] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Revised: 04/03/2007] [Accepted: 04/04/2007] [Indexed: 10/23/2022]
Abstract
A recent study [Tannan, V., Tommerdahl, M., Whitsel, B.L., 2006. Vibrotactile adaptation enhances spatial localization. Brain Res. 1102(1), 109-116 (Aug 2)] showed that pre-exposure of a skin region to a 5 s 25 Hz flutter stimulus ("adaptation") results in an approximately 2-fold improvement in the ability of neurologically healthy human adults to localize mechanical stimulation delivered to the same skin region that received the adapting stimulation. Tannan et al. [Tannan, V., Tommerdahl, M., Whitsel, B.L., 2006. Vibrotactile adaptation enhances spatial localization. Brain Res. 1102(1), 109-116 (Aug 2)] proposed that tactile spatial discriminative performance is improved following adaptation because adaptation is accompanied by an increase in the spatial contrast in the response of contralateral primary somatosensory cortex (SI) to mechanical skin stimulation--an effect identified in previous imaging studies of SI cortex in anesthetized non-human primates [e.g., Simons, S.B., Tannan, V., Chiu, J., Favorov, O.V., Whitsel, B.L., Tommerdahl, M, 2005. Amplitude-dependency of response of SI cortex to flutter stimulation. BMC Neurosci. 6(1), 43 (Jun 21) ; Tommerdahl, M., Favorov, O.V., Whitsel, B.L., 2002. Optical imaging of intrinsic signals in somatosensory cortex. Behav. Brain Res. 135, 83-91; Whitsel, B.L., Favorov, O.V., Tommerdahl, M., Diamond, M., Juliano, S., Kelly, D., 1989. Dynamic processes govern the somatosensory cortical response to natural stimulation. In: Lund, J.S., (Ed.), Sensory Processing in the Mammalian Brain. Oxford Univ. Press, New York, 79-107]. In the experiments described in this report, a paradigm identical to that employed previously by Tannan et al. [Tannan, V., Tommerdahl, M., Whitsel, B.L., 2006. Vibrotactile adaptation enhances spatial localization. Brain Res. 1102(1), 109-116 (Aug 2)] was used to study adults with autism. The results demonstrate that although cutaneous localization performance of adults with autism is significantly better than the performance of control subjects when the period of adapting stimulation is short (i.e., 0.5 s), tactile spatial discriminative capacity remained unaltered in the same subjects when the duration of adapting stimulation was increased (to 5 s). Both the failure of prior history of tactile stimulation to alter tactile spatial localization in adults with autism, and the better-than-normal tactile localization performance of adults with autism when the period of adaptation is short are concluded to be attributable to the deficient cerebral cortical GABAergic inhibitory neurotransmission characteristic of this disorder.
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Affiliation(s)
- M Tommerdahl
- Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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316
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Yip J, Soghomonian JJ, Blatt GJ. Decreased GAD67 mRNA levels in cerebellar Purkinje cells in autism: pathophysiological implications. Acta Neuropathol 2007; 113:559-68. [PMID: 17235515 DOI: 10.1007/s00401-006-0176-3] [Citation(s) in RCA: 197] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Revised: 11/14/2006] [Accepted: 11/14/2006] [Indexed: 10/23/2022]
Abstract
The recent identification of decreased protein levels of glutamate decarboxylase (GAD) 65 and 67 isoforms in the autistic cerebellar tissue raises the possibility that abnormal regulation of GABA production in individual neurons may contribute to the clinical features of autism. Reductions in Purkinje cell number have been widely reported in autism. It is not known whether the GAD changes also occur in Purkinje cells at the level of transcription. Using a novel approach, the present study quantified GAD67 mRNA, the most abundant isoform in Purkinje cells, using in situ hybridization in adult autistic and control cases. The results indicate that GAD67 mRNA level was reduced by 40% in the autistic group (P < 0.0001; two-tailed t test), suggesting that reduced Purkinje cell GABA input to the cerebellar nuclei potentially disrupts cerebellar output to higher association cortices affecting motor and/or cognitive function. These findings may also contribute to the understanding of previous reports of alterations in the GABAergic system in limbic and cerebro-cortical areas contributing to a more widespread pathophysiology in autistic brains.
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Affiliation(s)
- Jane Yip
- Department of Anatomy and Neurobiology, Boston University School of Medicine, 715 Albany St, R1003, Boston, MA 02118, USA
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317
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Erickson CA, Posey DJ, Stigler KA, Mullett J, Katschke AR, McDougle CJ. A retrospective study of memantine in children and adolescents with pervasive developmental disorders. Psychopharmacology (Berl) 2007; 191:141-7. [PMID: 17016714 DOI: 10.1007/s00213-006-0518-9] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 07/12/2006] [Indexed: 11/29/2022]
Abstract
RATIONALE There are no drugs that have been shown to effectively treat the core social impairment of autism. OBJECTIVES The purpose of this study was to examine the effectiveness and tolerability of memantine for social impairment in children and adolescents with pervasive developmental disorders (PDDs). MATERIALS AND METHODS Medical records of 18 patients with PDDs consecutively treated with open-label memantine were retrospectively reviewed. The data reviewed included prospectively obtained assessments of severity (S) and improvement (I) using the Clinical Global Impressions Scale (CGI). Pretrial and follow-up parent ratings were also available on six patients using the Aberrant Behavior Checklist (ABC). RESULTS Eighteen patients (15 male, 3 female; mean age=11.4 years, range 6-19 years) received memantine (mean dosage=10.1 mg/day, range 2.5-20 mg/day) over a mean duration of 19.3 weeks (range 1.5-56 weeks). Eleven of 18 (61%) patients were judged responders to memantine based on a rating of "much improved" or "very much improved" on the CGI-I. Significant improvement was also seen on the CGI-S. Improvement was primarily seen clinically in social withdrawal and inattention. Adverse effects occurred in 7 of 18 (39%) patients and led to drug discontinuation in 4 of 18 (22%) patients. Thirteen of 18 (72%) patients received stable doses of concomitant medications during the memantine trial. CONCLUSIONS In this open-label retrospective study, memantine was effective in a number of patients with PDDs. Controlled studies are warranted to further assess the efficacy and safety of memantine in PDDs.
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Affiliation(s)
- Craig A Erickson
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
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318
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Yamakawa H, Oyama S, Mitsuhashi H, Sasagawa N, Uchino S, Kohsaka S, Ishiura S. Neuroligins 3 and 4X interact with syntrophin-γ2, and the interactions are affected by autism-related mutations. Biochem Biophys Res Commun 2007; 355:41-6. [PMID: 17292328 DOI: 10.1016/j.bbrc.2007.01.127] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Accepted: 01/17/2007] [Indexed: 11/25/2022]
Abstract
Recently, neuroligins (NLs)3 and 4X have received much attention as autism-related genes. Here, we identified syntrophin-gamma2 (SNTG2) as a de novo binding partner of NL3. SNTG2 also bound to NL4X and NL4Y. Interestingly, the binding was influenced by autism-related mutations, implying that the impaired interaction between NLs and SNTG2 contributes to the etiology of autism.
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Affiliation(s)
- Hidekuni Yamakawa
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, 3-8-1 Komaba, Meguro-ku 153-8902, Japan
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319
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Bethea TC, Sikich L. Early pharmacological treatment of autism: a rationale for developmental treatment. Biol Psychiatry 2007; 61:521-37. [PMID: 17276749 PMCID: PMC2553755 DOI: 10.1016/j.biopsych.2006.09.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Revised: 09/02/2006] [Accepted: 09/24/2006] [Indexed: 11/25/2022]
Abstract
Autism is a dynamic neurodevelopmental syndrome in which disabilities emerge during the first three postnatal years and continue to evolve with ongoing development. We briefly review research in autism describing subtle changes in molecules important in brain development and neurotransmission, in morphology of specific neurons, brain connections, and in brain size. We then provide a general schema of how these processes may interact with particular emphasis on neurotransmission. In this context, we present a rationale for utilizing pharmacologic treatments aimed at modifying key neurodevelopmental processes in young children with autism. Early treatment with selective serotonin reuptake inhibitors (SSRIs) is presented as a model for pharmacologic interventions because there is evidence in autistic children for reduced brain serotonin synthesis during periods of peak synaptogenesis; serotonin is known to enhance synapse refinement; and exploratory studies with these agents in autistic children exist. Additional hypothetical developmental interventions and relevant published clinical data are described. Finally, we discuss the importance of exploring early pharmacologic interventions within multiple experimental settings in order to develop effective treatments as quickly as possible while minimizing risks.
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Affiliation(s)
- Terrence C Bethea
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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320
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Guptill JT, Booker AB, Gibbs TT, Kemper TL, Bauman ML, Blatt GJ. [3H]-Flunitrazepam-labeled Benzodiazepine Binding Sites in the Hippocampal Formation in Autism: A Multiple Concentration Autoradiographic Study. J Autism Dev Disord 2006; 37:911-20. [PMID: 17019626 DOI: 10.1007/s10803-006-0226-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Increasing evidence indicates that the GABAergic system in cerebellar and limbic structures is affected in autism. We extended our previous study that found reduced [(3)H]flunitrazepam-labeled benzodiazepine sites in the autistic hippocampus to determine whether this reduction was due to a decrease in binding site number (B (max)) or altered affinity (K (d)) to bind to the ligand. Quantitation of hippocampal lamina demonstrated a 20% reduction in B (max) indicating a trend toward a decreased number of benzodiazepine binding sites in the autistic group but normal K (d) values. A reduction in the number of hippocampal benzodiazepine binding sites suggests alterations in the modulation of GABA(A) receptors in the presence of GABA in the autistic brain, possibly resulting in altered inhibitory functioning of hippocampal circuitry.
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Affiliation(s)
- Jeffrey T Guptill
- Department of Anatomy and Neurobiology, Boston University School of Medicine, 715 Albany Street, R-1003, Boston, MA 02118, USA
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322
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Badcock C, Crespi B. Imbalanced genomic imprinting in brain development: an evolutionary basis for the aetiology of autism. J Evol Biol 2006; 19:1007-32. [PMID: 16780503 DOI: 10.1111/j.1420-9101.2006.01091.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We describe a new hypothesis for the development of autism, that it is driven by imbalances in brain development involving enhanced effects of paternally expressed imprinted genes, deficits of effects from maternally expressed genes, or both. This hypothesis is supported by: (1) the strong genomic-imprinting component to the genetic and developmental mechanisms of autism, Angelman syndrome, Rett syndrome and Turner syndrome; (2) the core behavioural features of autism, such as self-focused behaviour, altered social interactions and language, and enhanced spatial and mechanistic cognition and abilities, and (3) the degree to which relevant brain functions and structures are altered in autism and related disorders. The imprinted brain theory of autism has important implications for understanding the genetic, epigenetic, neurological and cognitive bases of autism, as ultimately due to imbalances in the outcomes of intragenomic conflict between effects of maternally vs. paternally expressed genes.
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Affiliation(s)
- C Badcock
- Department of Sociology, London School of Economics, London, UK
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323
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Chauhan A, Chauhan V. Oxidative stress in autism. PATHOPHYSIOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY FOR PATHOPHYSIOLOGY 2006; 13:171-81. [PMID: 16766163 DOI: 10.1016/j.pathophys.2006.05.007] [Citation(s) in RCA: 380] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Autism is a severe developmental disorder with poorly understood etiology. Oxidative stress in autism has been studied at the membrane level and also by measuring products of lipid peroxidation, detoxifying agents (such as glutathione), and antioxidants involved in the defense system against reactive oxygen species (ROS). Lipid peroxidation markers are elevated in autism, indicating that oxidative stress is increased in this disease. Levels of major antioxidant serum proteins, namely transferrin (iron-binding protein) and ceruloplasmin (copper-binding protein), are decreased in children with autism. There is a positive correlation between reduced levels of these proteins and loss of previously acquired language skills in children with autism. The alterations in ceruloplasmin and transferrin levels may lead to abnormal iron and copper metabolism in autism. The membrane phospholipids, the prime target of ROS, are also altered in autism. The levels of phosphatidylethanolamine (PE) are decreased, and phosphatidylserine (PS) levels are increased in the erythrocyte membrane of children with autism as compared to their unaffected siblings. Several studies have suggested alterations in the activities of antioxidant enzymes such as superoxide dismutase, glutathione peroxidase, and catalase in autism. Additionally, altered glutathione levels and homocysteine/methionine metabolism, increased inflammation, excitotoxicity, as well as mitochondrial and immune dysfunction have been suggested in autism. Furthermore, environmental and genetic factors may increase vulnerability to oxidative stress in autism. Taken together, these studies suggest increased oxidative stress in autism that may contribute to the development of this disease. A mechanism linking oxidative stress with membrane lipid abnormalities, inflammation, aberrant immune response, impaired energy metabolism and excitotoxicity, leading to clinical symptoms and pathogenesis of autism is proposed.
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Affiliation(s)
- Abha Chauhan
- NYS Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314, USA
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324
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Akbarian S, Huang HS. Molecular and cellular mechanisms of altered GAD1/GAD67 expression in schizophrenia and related disorders. ACTA ACUST UNITED AC 2006; 52:293-304. [PMID: 16759710 DOI: 10.1016/j.brainresrev.2006.04.001] [Citation(s) in RCA: 257] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 03/31/2006] [Accepted: 04/04/2006] [Indexed: 12/29/2022]
Abstract
The 67 and 65 kDa isoforms of glutamic acid decarboxylase, the key enzymes for GABA biosynthesis, are expressed at altered levels in postmortem brain of subjects diagnosed with schizophrenia and related disorders, including autism and bipolar illness. The predominant finding is a decrease in GAD67 mRNA levels, affecting multiple brain regions, including prefrontal and temporal cortex. Postmortem studies, in conjunction with animal models, identified several mechanisms that contribute to the dysregulation of GAD67 in cerebral cortex. These include disordered connectivity formation during development, abnormal expression of Reelin and neural cell adhesion molecule (NCAM) glycoproteins, defects in neurotrophin signaling and alterations in dopaminergic and glutamatergic neurotransmission. These mechanisms are likely to operate in conjunction with genetic risk factors for psychosis, including sequence polymorphisms residing in the promoter of GAD1 (2q31), the gene encoding GAD67. We propose an integrative model, with multiple molecular and cellular mechanisms contributing to transcriptional dysregulation of GAD67 and cortical dysfunction in psychosis.
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Affiliation(s)
- Schahram Akbarian
- Department of Psychiatry, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Medical School, 303 Belmont Street, Worcester, 01604, USA.
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325
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Abstract
This review paper integrates recent structural and functional imaging, postmortem, animal lesion, and neurochemical research about the pathophysiology of autism. An understanding of the neurobiological correlates of autism is becoming increasingly important as more children are diagnosed with the condition and funding for well-targeted interventions increases. Converging evidence suggests that autism involves abnormalities in brain volume, neurotransmitter systems, and neuronal growth. In addition, evidence firmly links autism with abnormalities in the cerebellum, the medial temporal lobe, and the frontal lobe. Potential implications of these findings and suggestions for future research are reviewed.
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Affiliation(s)
- Helen E Penn
- Clinical-Developmental Psychology Program, York University, Toronto, Ontario M3J IP3, Canada.
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326
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Lam KSL, Aman MG, Arnold LE. Neurochemical correlates of autistic disorder: a review of the literature. RESEARCH IN DEVELOPMENTAL DISABILITIES 2006; 27:254-89. [PMID: 16002261 DOI: 10.1016/j.ridd.2005.03.003] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Revised: 01/05/2005] [Accepted: 03/17/2005] [Indexed: 05/03/2023]
Abstract
Review of neurochemical investigations in autistic disorder revealed that a wide array of transmitter systems have been studied, including serotonin, dopamine, norepinephrine, acetylcholine, oxytocin, endogenous opioids, cortisol, glutamate, and gamma-aminobutyric acid (GABA). These studies have been complicated by the fact that autism is a very heterogeneous disorder which often presents with comorbid behavioral problems. In addition, many of these studies employed very small samples and inappropriate control groups, making it difficult to draw conclusions with confidence. Overall, serotonin appears to have the most empirical evidence for a role in autism, but this requires further investigation and replication. There is little support for the notion that a dysfunction of norepinephrine or the endogenous opioids are related to autism. The role of dopaminergic functioning has not been compelling thus far, though conflicting findings on central dopamine turnover require further study. Promising new areas of study may include possible dysfunction of the cholinergic system, oxytocin, and amino acid neurotransmitters. Implications for pharmacotherapy are briefly discussed for each neurotransmitter system with brief research examples. Review of this work emphasizes the need for future studies to control for subject variables, such as race, sex, pubertal status, and distress associated with blood draws, which can affect measures of neurochemical function. In addition, research in neurochemistry must continue to work in concert with other subspecialties to form a more comprehensive and theory-based approach to the neurobiological correlates of autistic disorder.
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Affiliation(s)
- Kristen S L Lam
- Neurodevelopmental Disorders Research Center, University of North Carolina at Chapel Hill, USA
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327
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Schmitz C, van Kooten IAJ, Hof PR, van Engeland H, Patterson PH, Steinbusch HWM. Autism: neuropathology, alterations of the GABAergic system, and animal models. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2006; 71:1-26. [PMID: 16512344 DOI: 10.1016/s0074-7742(05)71001-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Christoph Schmitz
- Department of Psychiatry and Neuropsychology, Division of Cellular Neuroscience Maastricht University, The Netherlands
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328
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Walker MA. Evaluation of recent patent applications for the diagnosis and treatment of autism and pervasive developmental disorders. Expert Opin Ther Pat 2006. [DOI: 10.1517/13543776.16.3.249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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329
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Schmitz N, Rubia K, Daly E, Smith A, Williams S, Murphy DGM. Neural correlates of executive function in autistic spectrum disorders. Biol Psychiatry 2006; 59:7-16. [PMID: 16140278 DOI: 10.1016/j.biopsych.2005.06.007] [Citation(s) in RCA: 271] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Revised: 05/24/2005] [Accepted: 06/03/2005] [Indexed: 12/20/2022]
Abstract
BACKGROUND Some clinical characteristics of high-functioning individuals with autistic spectrum disorder (ASD) such as repetitive stereotyped behaviors, perseveration, and obsessionality have been related to executive function (EF) deficits, more specifically to deficits in inhibitory control and set shifting and mediating frontostriatal neural pathways. However, to date, no functional imaging study on ASD has investigated inhibition and cognitive flexibility and no one has related EF brain activation to brain structure. METHODS We compared brain activation (using functional magnetic resonance imaging) in 10 normal intelligence adults with ASD and 12 healthy control subjects during three different EF tasks: 1) motor-inhibition (GO/NO-GO); 2) cognitive interference-inhibition (spatial STROOP); and 3) set shifting (SWITCH). Using voxel-based morphometry, we investigated if cortical areas which were functionally different in people with ASD were also anatomically abnormal. RESULTS Compared with control subjects, ASD individuals showed significantly increased brain activation in 1) left inferior and orbital frontal gyrus (motor-inhibition); 2) left insula (interference-inhibition); and 3) parietal lobes (set shifting). Moreover, in individuals with ASD, increased frontal gray matter density and increased functional activation shared the same anatomical location. CONCLUSIONS Our findings suggest an association between successful completion of EF tasks and increased brain activation in people with ASD, which partially may be explained by differences in brain anatomy.
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Affiliation(s)
- Nicole Schmitz
- Department of Psychological Medicine, Section of Brain Maturation, Institute of Psychiatry, King' College London, UK.
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330
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Dhossche DM, Rout U. Are Autistic and Catatonic Regression Related? A Few Working Hypotheses Involving Gaba, Purkinje Cell Survival, Neurogenesis, and ECT. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2006; 72:55-79. [PMID: 16697291 DOI: 10.1016/s0074-7742(05)72004-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Autistic regression seems to occur in about a quarter of children with autism. Its cause is unknown. Late-onset autistic regression, that is, after 2 years of age, shares some features with catatonic regression. A working hypothesis is developed that some children with autistic regression suffer from early-onset catatonic regression. This hypothesis cannot be answered from current data and is difficult to address in clinical studies in the absence of definite markers of autistic and catatonic regression. Treatment implications are theoretical and involve the potential use of anticatatonic treatments for autistic regression. Focus is on electroconvulsive therapy (ECT)--an established but controversial treatment that is viewed by many, but not all, as the most effective treatment for severe, life-threatening catatonic regression. Clinical trials of ECT in early- or late-onset autistic regression in children have not been done yet. The effects of electroconvulsive seizures--the experimental analogue of ECT--should also be tested in gamma-aminobutyric acid-ergic animal models of autistic regression, autism, catatonia, and other neurodevelopmental disorders. Purkinje cell survival and neurogenesis are putative outcome measures in these models.
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Affiliation(s)
- Dirk Marcel Dhossche
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA
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331
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Dean C, Dresbach T. Neuroligins and neurexins: linking cell adhesion, synapse formation and cognitive function. Trends Neurosci 2005; 29:21-9. [PMID: 16337696 DOI: 10.1016/j.tins.2005.11.003] [Citation(s) in RCA: 234] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 09/02/2005] [Accepted: 11/10/2005] [Indexed: 12/20/2022]
Abstract
Cell adhesion represents the most direct way of coordinating synaptic connectivity in the brain. Recent evidence highlights the importance of a trans-synaptic interaction between postsynaptic neuroligins and presynaptic neurexins. These transmembrane molecules bind each other extracellularly to promote adhesion between dendrites and axons. This signals the recruitment of presynaptic and postsynaptic molecules to form a functional synapse. Remarkably, neuroligins alone can induce the formation of fully functional presynaptic terminals in contacting axons. Conversely, neurexins alone can induce postsynaptic differentiation and clustering of receptors in dendrites. Therefore, the neuroligin-neurexin interaction has the unique ability to act as a bi-directional trigger of synapse formation. Here, we review several recent studies that offer clues as to how these proteins form synapses and how they might function in the brain to establish and modify neuronal network properties and cognition.
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Affiliation(s)
- Camin Dean
- Department of Physiology, University of Wisconsin Medical School, Madison, WI 53706, USA.
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332
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Abstract
Autism is a complex, behaviorally defined, developmental brain disorder with an estimated prevalence of 1 in 1,000. It is now clear that autism is not a disease, but a syndrome with a strong genetic component. The etiology of autism is poorly defined both at the cellular and the molecular levels. Based on the fact that seizure activity is frequently associated with autism and that abnormal evoked potentials have been observed in autistic individuals in response to tasks that require attention, several investigators have recently proposed that autism might be caused by an imbalance between excitation and inhibition in key neural systems including the cortex. Despite considerable ongoing effort toward the identification of chromosome regions affected in autism and the characterization of many potential gene candidates, only a few genes have been reproducibly shown to display specific mutations that segregate with autism, likely because of the complex polygenic nature of this syndrome. Among those, several candidate genes have been shown to control the early patterning and/or the late synaptic maturation of specific neuronal subpopulations controlling the balance between excitation and inhibition in the developing cortex and cerebellum. In the present article, we review our current understanding of the developmental mechanisms patterning the balance between excitation and inhibition in the context of the neurobiology of autism.
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MESH Headings
- Autistic Disorder/genetics
- Autistic Disorder/metabolism
- Autistic Disorder/physiopathology
- Brain/abnormalities
- Brain/metabolism
- Brain/physiopathology
- Brain Stem/abnormalities
- Brain Stem/metabolism
- Brain Stem/physiopathology
- Cerebellum/abnormalities
- Cerebellum/metabolism
- Cerebellum/physiopathology
- Chromosomes, Human, Pair 15/genetics
- Chromosomes, Human, Pair 16/genetics
- Chromosomes, Human, Pair 17/genetics
- Chromosomes, Human, Pair 19/genetics
- Chromosomes, Human, Pair 20/genetics
- Gene Expression/genetics
- Genetic Markers
- Glutamic Acid/metabolism
- Humans
- Magnetic Resonance Imaging
- gamma-Aminobutyric Acid/metabolism
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Affiliation(s)
- Franck Polleux
- Department of Pharmacology-Neuroscience Center, School of Medicine, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA.
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333
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Jeffries AR, Curran S, Elmslie F, Sharma A, Wenger S, Hummel M, Powell J. Molecular and phenotypic characterization of ring chromosome 22. Am J Med Genet A 2005; 137:139-47. [PMID: 16059935 DOI: 10.1002/ajmg.a.30780] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We performed a phenotype study of 35 individuals (19 males, 16 females) with ring chromosome 22 or r(22) with a mean age of 10 years. In common with other studies, a phenotype of moderate-to-profound learning difficulties and delay or absence of speech affected all individuals with the exception of the case with the smallest deletion. Autistic traits were significantly associated with r(22), as shown by an autism screening questionnaire. Mild and variable dysmorphic features, predominantly craniofacial and distal limb, were observed. Internal organ involvement was uncommon. Even though ring chromosomes are reportedly associated with growth abnormalities, only 2 out of 24 individuals showed evidence of growth failure, while 2 showed accelerated growth. Chromosome 22 long arm deletions, as determined by hemizygosity for informative microsatellite markers, varied from <67 kb to 10.2 Mb in size (or <0.15 to 21% of total chromosome length), with no significant differences in the parental origin of the ring chromosome. Few phenotypic features correlated with deletion size suggesting a critical gene, or genes, of major effect lies close to the telomere. Loss of the SHANK3/PROSAP2 gene has been proposed to be responsible for the main neurological developmental deficits observed in 22q13 monosomies. This study supports this candidate gene by identifying a phenotypically normal r(22) individual whose ring chromosome does not disrupt SHANK3. All other r(22) individuals were hemizygous for SHANK3, and we propose it to be a candidate gene for autism or abnormal brain development.
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Affiliation(s)
- Aaron R Jeffries
- Department of Neuroscience, Institute of Psychiatry, Denmark Hill, London SE5 8AF, United Kingdom
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334
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Dhossche DM, Song Y, Liu Y. Is There A Connection Between Autism, Prader‐Willi Syndrome, Catatonia, And GABA? INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 71:189-216. [PMID: 16512352 DOI: 10.1016/s0074-7742(05)71009-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Dirk M Dhossche
- Department of Psychiatry & Human Behavior, University of Mississippi Medical Center, Jackson 39216, USA
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335
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Fiszman ML. Insights into GABA functions in the developing cerebellum. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 71:95-112. [PMID: 16512347 DOI: 10.1016/s0074-7742(05)71004-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Affiliation(s)
- Mónica L Fiszman
- Instituto de Investigaciones Farmacologicas-CONICET, Ciudad de Buenos Aires, Argentina
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336
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Takayama C. GABAergic signaling in the developing cerebellum. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 71:63-94. [PMID: 16512346 DOI: 10.1016/s0074-7742(05)71003-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Chitoshi Takayama
- Department of Molecular Neuroanatomy, Hokkaido University School of Medicine, Sapporo, Japan
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337
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Fatemi SH, Hossein Fatemi S, Stary JM, Earle JA, Araghi-Niknam M, Eagan E. GABAergic dysfunction in schizophrenia and mood disorders as reflected by decreased levels of glutamic acid decarboxylase 65 and 67 kDa and Reelin proteins in cerebellum. Schizophr Res 2005; 72:109-22. [PMID: 15560956 DOI: 10.1016/j.schres.2004.02.017] [Citation(s) in RCA: 198] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2003] [Revised: 02/05/2004] [Accepted: 02/13/2004] [Indexed: 01/22/2023]
Abstract
BACKGROUND Glutamic acid decarboxylase (GAD) is the rate limiting enzyme responsible for conversion of glutamate to gamma-aminobutyric acid (GABA) regulating levels of glutamate and GABA in the mammalian brain. Reelin is an extracellular matrix protein that helps in normal lamination of the embryonic brain and subserves synaptic plasticity in adult brain. Both GAD and Reelin are colocalized to the same GABAergic interneurons in several brain sites. We hypothesized that levels of GAD and Reelin would be altered in cerebellum of subjects with schizophrenia and mood disorders differentially vs. controls. METHODS We employed SDS-PAGE and Western blotting to measure levels of GAD isomers 65 and 67 kDa and Reelin isoforms 410-, 330- and 180-kDa proteins as well as beta-actin in cerebellum of subjects with schizophrenia, bipolar disorder and major depression vs. controls (N = 15 per group). RESULTS GAD 65- and 67-kDa levels were decreased significantly in bipolar, depressed and schizophrenic subjects (p < 0.05) vs. controls. Reelin 410- and 180-kDa proteins decreased significantly (p < 0.05) in bipolar subjects vs. controls. Reelin 180 kDa was decreased significantly (p < 0.05) in schizophrenics vs. controls. beta-Actin levels did not vary significantly between groups. There were no significant effects of confounding variables on levels of various proteins. CONCLUSION This study demonstrates for the first time significant deficits in GABAergic markers Reelin and GAD 65 and 67 proteins in bipolar subjects and global deficits in the latter proteins in schizophrenia and mood disorders, accounting for the reported alterations in CSF/plasma levels of glutamate and GABA in these disorders.
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Affiliation(s)
- S Hossein Fatemi
- Department of Psychiatry, Division of Neuroscience Research, University of Minnesota Medical School, MMC #392, 420 Delaware Street SE, Minneapolis, MN 55455, USA.
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338
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Blatt GJ. GABAergic Cerebellar System In Autism: A Neuropathological And Developmental Perspective. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 71:167-78. [PMID: 16512350 DOI: 10.1016/s0074-7742(05)71007-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- Gene J Blatt
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Massachusetts 02118, USA
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339
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Rabionet R, Jaworski JM, Ashley-Koch AE, Martin ER, Sutcliffe JS, Haines JL, Delong GR, Abramson RK, Wright HH, Cuccaro ML, Gilbert JR, Pericak-Vance MA. Analysis of the autism chromosome 2 linkage region: GAD1 and other candidate genes. Neurosci Lett 2004; 372:209-14. [PMID: 15542242 DOI: 10.1016/j.neulet.2004.09.037] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Revised: 09/14/2004] [Accepted: 09/17/2004] [Indexed: 10/26/2022]
Abstract
Autism has a strong and complex genetic component, involving several genes. Genomic screens, including our own, have shown suggestive evidence for linkage over a 20-30 cM region on chromosome 2q31-q33. Two subsequent reports showed that the linkage evidence increased in the subset of families with phrase speech delay (PSD), defined as onset of phrase speech later than 3 years of age. To further investigate the linkage in the presumptive candidate region, microsatellite markers in a 2 cM grid covering the interval from 164 to 203 cM were analyzed in 110 multiplex (2 or more sampled autism patients) families. A maximum heterogeneity LOD (HLOD) score of 1.54 was detected at D2S1776 (173 cM) in the overall dataset (dominant model), increasing to 1.71 in the PSD subset. While not conclusive, these data continue to provide suggestive evidence for linkage, particularly considering replication by multiple independent groups. Positive LOD scores extended over the entire region, continuing to define a broad candidate interval. Association studies were performed on several functional candidates mapping within the region. These included GAD1, encoding GAD67, whose levels are reduced in autopsy brain material from autistic subjects, and STK17B, ABI2, CTLA4, CD28, NEUROD1, PDE1A, HOXD1 and DLX2. We found no evidence for significant allelic association between autism and any of these candidates, suggesting that they do not play a major role in the genetics of autism or that substantial allelic heterogeneity at any one of these loci dilutes potential disease-allele association.
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Affiliation(s)
- Raquel Rabionet
- Department of Medicine, Center for Human Genetics, 595 LaSalle St., Box 3445, Duke University Medical Center, Durham, NC 27710, USA
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340
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Cheng CM, Hicks K, Wang J, Eagles DA, Bondy CA. Caloric restriction augments brain glutamic acid decarboxylase-65 and -67 expression. J Neurosci Res 2004; 77:270-6. [PMID: 15211593 DOI: 10.1002/jnr.20144] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The ketogenic diet is a very low-carbohydrate, high-fat diet used to treat refractory epilepsy. We hypothesized that this diet may act by increasing expression of glutamic acid decarboxylase (GAD), the rate-limiting enzyme in gamma-aminobutyric acid (GABA) synthesis. Thus, we evaluated brain GAD levels in a well-established, seizure-suppressing, rodent model of the ketogenic diet. Because the diet is most effective when administered with a modest ( approximately 10%) calorie restriction, we studied three groups of animals: rats fed ad libitum standard rat chow (Ad lib-Std); calorie-restricted standard chow (CR-Std); and an isocaloric, calorie-restricted ketogenic diet (CR-Ket). We found that GAD67 mRNA was significantly increased in the inferior and superior colliculi and cerebellar cortex in both CR diet groups compared with control (e.g., by 45% in the superior colliculus and by 71% in the cerebellar cortex; P <.001). GAD65 mRNA was selectively increased in the superior colliculus and temporal cortex in both CR-Std and CR-Ket diet groups compared with ad lib controls. The only apparent CR-Ket-specific effect was a 30% increase in GAD67 mRNA in the striatum (P =.03). Enhanced GAD immunoreactivity was detected in parallel with the mRNA changes. These data clearly show that calorie restriction increases brain GAD65 and -67 expression in several brain regions, independent of ketogenic effects. These observations may explain why caloric restriction improves the efficacy of the ketogenic diet in treating epilepsy and suggest that diet modification might be useful in treatment of a number of brain disorders characterized by impaired GAD or GABA activity.
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Affiliation(s)
- Clara M Cheng
- Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
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341
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Abstract
We are on the brink of exciting discoveries into the molecular genetic underpinnings of autism spectrum disorder. Overwhelming evidence of genetic involvement coupled with increased societal attention to the disorder has drawn in more researchers and more research funding. Autism is a strongly genetic yet strikingly complex disorder, in which evidence from different cases supports chromosomal disorders, rare single gene mutations, and multiplicative effects of common gene variants. With more and more interesting yet sometimes divergent findings emerging every year, it is tempting to view these initial molecular studies as so much noise, but the data have also started to coalesce in certain areas. In particular, recent studies in families with autism spectrum disorder have identified uncommon occurrences of a novel genetic syndrome caused by disruptions of the NLGN4 gene on chromosome Xp22. Previous work had identified another uncommon syndrome that is caused by maternal duplications of the chromosome 15q11-13 region. We highlight other converging findings, point toward those areas most likely to yield results, and emphasize the contributions of multiple approaches to identifying the genes of interest.
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Allen G, Müller RA, Courchesne E. Cerebellar function in autism: functional magnetic resonance image activation during a simple motor task. Biol Psychiatry 2004; 56:269-78. [PMID: 15312815 DOI: 10.1016/j.biopsych.2004.06.005] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2003] [Revised: 05/17/2004] [Accepted: 06/04/2004] [Indexed: 11/16/2022]
Abstract
BACKGROUND The cerebellum is one of the most consistent sites of neuroanatomic abnormality in autism, yet it is still unclear how such pathology impacts cerebellar function. In normal subjects, we previously demonstrated with functional magnetic resonance imaging (fMRI) a dissociation between cerebellar regions involved in attention and those involved in a simple motor task, with motor activation localized to the anterior cerebellum ipsilateral to the moving hand. The purpose of the present investigation was to examine activation in the cerebella of autistic patients and normal control subjects performing this motor task. METHODS We studied eight autistic patients and eight matched normal subjects, using fMRI. An anatomic region-of-interest approach was used, allowing a detailed examination of cerebellar function. RESULTS Autistic individuals showed significantly increased motor activation in the ipsilateral anterior cerebellar hemisphere relative to normal subjects, in addition to atypical activation in contralateral and posterior cerebellar regions. Moreover, increased activation was correlated with the degree of cerebellar structural abnormality. CONCLUSIONS These findings strongly suggest dysfunction of the autistic cerebellum that is a reflection of cerebellar anatomic abnormality. This neurofunctional deficit might be a key contributor to the development of certain diagnostic features of autism (e.g., impaired communication and social interaction, restricted interests, and stereotyped behaviors).
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Affiliation(s)
- Greg Allen
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Araghi-Niknam M, Fatemi SH. Levels of Bcl-2 and P53 are altered in superior frontal and cerebellar cortices of autistic subjects. Cell Mol Neurobiol 2004; 23:945-52. [PMID: 14964781 DOI: 10.1023/b:cemn.0000005322.27203.73] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. Autistic disease (AD) is a severe neuropsychiatric disorder affecting 2-4 children per 10,000. We have recently shown reduction of Bcl-2 and increase in P53, two important markers of apoptosis, in parietal cortex of autistic subjects. 2. We hypothesized that brain levels of Bcl-2 and P53 would also be altered in superior frontal cortex and cerebellum of age-, sex, and postmortem-interval (PMI)-matched autistic subjects (N = 5 autistic, N = 4 controls). 3. Brain extracts were prepared from superior frontal cortex and cerebellum and subjected to Western blotting. 4. Results showed that levels of Bcl-2 decreased by 38% and 36% in autistic superior frontal and cerebellar cortices, respectively when compared to control tissues. By the same token, levels of P53 increased by 67.5% and 38% in the same brain areas in autistic subjects vs. controls respectively. Calculations of ratios of Bcl-2/P53 values also decreased by 75% and 43% in autistic frontal and cerebellar cortices vs. controls respectively. The autistic cerebellar values were significantly reduced (p < 0.08) vs. control only. There were no significant differences in levels of beta-actin between the two groups. Additionally, there were no correlations between Bcl-2, P53, and beta-actin concentrations vs. age or PMI in either group. 5. These results confirm and extend previous data that levels of Bcl-2 and P53 are altered in three important brain tissues, i.e. frontal, parietal, and cerebellar cortices of autistic subjects, alluding to deranged apoptotic mechanisms in autism.
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Affiliation(s)
- Mohsen Araghi-Niknam
- Department of Neuroscience, Division of Neuroscience Research, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
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344
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Martin-Ruiz CM, Lee M, Perry RH, Baumann M, Court JA, Perry EK. Molecular analysis of nicotinic receptor expression in autism. ACTA ACUST UNITED AC 2004; 123:81-90. [PMID: 15046869 DOI: 10.1016/j.molbrainres.2004.01.003] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2004] [Indexed: 11/19/2022]
Abstract
Autism is a developmental disorder of unknown aetiopathology and lacking any specific pharmacological therapeutic intervention. Neurotransmitters such as serotonin, gamma-aminobutyric acid (GABA) and acetylcholine have been implicated. Abnormalities in nicotinic acetylcholine receptors have been identified including cortical loss of binding to the alpha4/beta2 subtype and increase in cerebellar alpha7 binding. Receptor expression (mRNA) has not so far been systematically examined. This study aims to further explore the role of nicotinic receptors in autism by analysing nicotinic receptor subunit mRNA in conjunction with protein levels and receptor binding in different brain areas. Quantitative RT-PCR for alpha4, alpha7 and beta2 subunit mRNA expression levels; alpha3, alpha4, alpha7 and beta2 subunit protein expression immunochemistry and specific radioligand receptor binding were performed in adult autism and control brain samples from cerebral cortex and cerebellum. Alpha4 and beta2 protein expression and receptor binding density as well as alpha4 mRNA levels were lower in parietal cortex in autism, while alpha7 did not change for any of these parameters. In cerebellum, alpha4 mRNA expression was increased, whereas subunit protein and receptor levels were decreased. Alpha7 receptor binding in cerebellum was increased alongside non-significant elevations in mRNA and protein expression levels. No significant changes were found for beta2 in cerebellum. The data obtained, using complementary measures of receptor expression, indicate that reduced gene expression of the alpha4beta2 nicotinic receptor in the cerebral cortex is a major feature of the neurochemical pathology of autism, whilst post-transcriptional abnormalities of both this and the alpha7 subtype are apparent in the cerebellum. The findings point to dendritic and/or synaptic nicotinic receptor abnormalities that may relate to disruptions in cerebral circuitry development.
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Affiliation(s)
- C M Martin-Ruiz
- Joint MRC/University of Newcastle upon Tyne, Centre Development in Clinical Brain Ageing, Department of Neuropathology, Newcastle General Hospital, Newcastle upon Tyne NE4 6BE, UK.
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Bacchelli E, Blasi F, Biondolillo M, Lamb JA, Bonora E, Barnby G, Parr J, Beyer KS, Klauck SM, Poustka A, Bailey AJ, Monaco AP, Maestrini E. Screening of nine candidate genes for autism on chromosome 2q reveals rare nonsynonymous variants in the cAMP-GEFII gene. Mol Psychiatry 2003; 8:916-24. [PMID: 14593429 DOI: 10.1038/sj.mp.4001340] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The results from several genome scans indicate that chromosome 2q21-q33 is likely to contain an autism susceptibility locus. We studied the potential contribution of nine positional and functional candidate genes: TBR-1; GAD1; DLX1; DLX2; cAMP-GEFII; CHN1; ATF2; HOXD1 and NEUROD1. Screening these genes for DNA variants and association analysis using intragenic single nucleotide polymorphisms did not provide evidence for a major role in the aetiology of autism. Four rare nonsynonymous variants were identified, however, in the cAMP-GEFII gene. These variants were present in five families, where they segregate with the autistic phenotype, and were not observed in control individuals. The significance of these variants is unclear, as their low frequency in IMGSAC families does not account for the relatively strong linkage signal at the 2q locus. Further studies are needed to clarify the contribution of cAMP-GEFII gene variants to autism susceptibility.
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Affiliation(s)
- E Bacchelli
- Dipartimento di Biologia Evoluzionistica Sperimentale, University of Bologna, Bologna, Italy
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Rubenstein JLR, Merzenich MM. Model of autism: increased ratio of excitation/inhibition in key neural systems. GENES, BRAIN, AND BEHAVIOR 2003; 2:255-67. [PMID: 14606691 PMCID: PMC6748642 DOI: 10.1034/j.1601-183x.2003.00037.x] [Citation(s) in RCA: 1810] [Impact Index Per Article: 86.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Autism is a severe neurobehavioral syndrome, arising largely as an inherited disorder, which can arise from several diseases. Despite recent advances in identifying some genes that can cause autism, its underlying neurological mechanisms are uncertain. Autism is best conceptualized by considering the neural systems that may be defective in autistic individuals. Recent advances in understanding neural systems that process sensory information, various types of memories and social and emotional behaviors are reviewed and compared with known abnormalities in autism. Then, specific genetic abnormalities that are linked with autism are examined. Synthesis of this information leads to a model that postulates that some forms of autism are caused by an increased ratio of excitation/inhibition in sensory, mnemonic, social and emotional systems. The model further postulates that the increased ratio of excitation/inhibition can be caused by combinatorial effects of genetic and environmental variables that impinge upon a given neural system. Furthermore, the model suggests potential therapeutic interventions.
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Affiliation(s)
- J L R Rubenstein
- Nina Ireland Laboratory of Developmental Neurobiology, Center for Neurobiology and Psychiatry, Department of Psychiatry, University of California at San Francisco, San Francisco, CA 94143-0984, USA.
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