PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-5 (5)
 

Clipboard (0)
None
Journals
Year of Publication
Document Types
1.  Slc25a12 disruption alters myelination and neurofilaments: A model for a hypomyelination syndrome and childhood neurodevelopmental disorders 
Biological psychiatry  2009;67(9):887-894.
Background
SLC25A12, a susceptibility gene for autism spectrum disorders (ASDs) that is mutated in a neurodevelopmental syndrome, encodes a mitochondrial aspartate/glutamate carrier (AGC1). AGC1 is an important component of the malate/aspartate shuttle, a crucial system supporting oxidative phosphorylation and ATP production.
Methods
We characterized mice with a disruption of the Slc25a12 gene, followed by confirmatory in vitro studies.
Results
Slc25a12-knockout mice, which showed no AGC1 by immunoblotting, were born normally but displayed delayed development and died around 3 weeks after birth. In P13-14 knockout brains, the brains were smaller with no obvious alteration in gross structure. However, we found a reduction in myelin basic protein (MBP)-positive fibers, consistent with a previous report. Furthermore, the neocortex of knockout mice contained abnormal neurofilamentous accumulations in neurons, suggesting defective axonal transport and/or neurodegeneration. Slice cultures prepared from knockout mice also showed a myelination defect, and reduction of Slc25a12 in rat primary oligodendrocytes led to a cellautonomous reduction in MBP expression. Myelin deficits in slice cultures from knockout mice could be reversed by administration of pyruvate, indicating that reduction in AGC1 activity leads to reduced production of aspartate/N-acetyl aspartate (NAA) and/or alterations in the NADH/NAD+ ratio, resulting in myelin defects.
Conclusions
Our data implicate AGC1 activity in myelination and in neuronal structure, and indicate that while loss of AGC1 leads to hypomyelination and neuronal changes, subtle alterations in AGC1 expression could affect brain development contributing to increased autism susceptibility.
doi:10.1016/j.biopsych.2009.08.042
PMCID: PMC4067545  PMID: 20015484
Malate/aspartate shuttle; mitochondria; N-acetyl aspartate (NAA); neuron-oligodendrocyte interactions; pyruvate
2.  Linking White and Grey Matter in Schizophrenia: Oligodendrocyte and Neuron Pathology in the Prefrontal Cortex 
Neuronal circuitry relies to a large extent on the presence of functional myelin produced in the brain by oligodendrocytes. Schizophrenia has been proposed to arise partly from altered brain connectivity. Brain imaging and neuropathologic studies have revealed changes in white matter and reduction in myelin content in patients with schizophrenia. In particular, alterations in the directionality and alignment of axons have been documented in schizophrenia. Moreover, the expression levels of several myelin-related genes are decreased in postmortem brains obtained from patients with schizophrenia. These findings have led to the formulation of the oligodendrocyte/myelin dysfunction hypothesis of schizophrenia. In this review, we present a brief overview of the neuropathologic findings obtained on white matter and oligodendrocyte status observed in schizophrenia patients, and relate these changes to the processes of brain maturation and myelination. We also review recent data on oligodendrocyte/myelin genes, and present some recent mouse models of myelin deficiencies. The use of transgenic and mutant animal models offers a unique opportunity to analyze oligodendrocyte and neuronal changes that may have a clinical impact. Lastly, we present some recent morphological findings supporting possible causal involvement of white and grey matter abnormalities, in the aim of determining the morphologic characteristics of the circuits whose alteration leads to the cortical dysfunction that possibly underlies the pathogenesis of schizophrenia.
doi:10.3389/neuro.05.009.2009
PMCID: PMC2713751  PMID: 19636386
myelin; myelin-related genes; development; anterior cingulate cortex; cingulum bundle
3.  Pepsin Pretreatment Allows Collagen IV Immunostaining of Blood Vessels in Adult Mouse Brain 
Journal of neuroscience methods  2007;163(1):76-82.
While the brain vasculature can be imaged with many methods, immunohistochemistry has distinct advantages due to its simplicity and applicability to archival tissue. However, immunohistochemical staining of the murine brain vasculature in aldehyde fixed tissue has proven elusive and inconsistent using current protocols. Here we investigated whether antigen retrieval methods could improve vascular staining in the adult mouse brain. We found that pepsin digestion prior to immunostaining unmasked widespread collagen IV staining of the cerebrovasculature in the adult mouse brain. Pepsin treatment also unmasked widespread vascular staining with laminin, but only marginally improved isolectin B4 staining and did not enhance vascular staining with fibronectin, perlecan or CD146. Collagen IV immunoperoxidase staining was easily combined with cresyl violet counterstaining making it suitable for stereological analyses of both vascular and neuronal parameters in the same tissue section. This method should be widely applicable for labeling the brain vasculature of the mouse in aldehyde fixed tissue from both normal and pathological states.
doi:10.1016/j.jneumeth.2007.02.020
PMCID: PMC1931483  PMID: 17403541
adult; antigen retrieval; blood vessels; brain; collagen IV; immunohistochemistry; mouse; pepsin
4.  In vivo 1H-magnetic resonance spectroscopy study of the attentional networks in autism 
Brain research  2010;1380:198-205.
Attentional dysfunction is one of the most consistent findings in individuals with autism spectrum disorders (ASD). However, the significance of such findings for the pathophysiology of autism is unclear. In this study, we investigated cellular neurochemistry with proton magnetic resonance spectroscopy imaging (1H-MRS) in brain regions associated with networks subserving alerting, orienting, and executive control of attention in patients with ASD. Concentrations of cerebral N-acetyl-aspartate (NAA), creatinine + phosphocreatinine, choline-containing compounds, myo-inositol (Ins) and glutamate + glutamine (Glx) were determined by 3 T 1H-MRS examinations in 14 high-functioning medication-free adults with a diagnosis of ASD and 14 age- and IQ-matched healthy controls (HC) in the anterior cingulate cortex (ACC), thalamus, temporoparietal junction (TPJ), and areas near or along the intraparietal sulcus (IPS). Compared to HC group, the ASD group showed significantly lower Glx concentrations in right ACC and reduced Ins in left TPJ. This study provides evidence of abnormalities in neurotransmission related to networks subserving executive control and alerting of attention, functions which have been previously implicated in ASD pathogenesis.
doi:10.1016/j.brainres.2010.12.057
PMCID: PMC3073642  PMID: 21185269
autism; spectroscopy; glutamate; anterior cingulate cortex; intraparietal sulcus; myo-inositol
5.  PERIPHERAL MYELIN PROTEIN-22 IS EXPRESSED IN CNS MYELIN 
Translational neuroscience  2010;1(4):282-285.
Myelin abnormalities exist in schizophrenia leading to the hypothesis that oligodendrocyte dysfunction plays a role in the pathophysiology of the disease. The expression of the mRNA for the peripheral myelin protein-22 (PMP-22) is decreased in schizophrenia and recent genetic evidence suggests a link between PMP-22 and schizophrenia. While PMP-22 mRNA is found in both rodent and human brain it has been generally thought that no protein expression occurs. Here we show that PMP-22 protein is present in myelin isolated from adult mouse and human brain. These results suggest that PMP-22 protein likely plays a role in the maintenance and function of central nervous system (CNS) myelin and provide an explanation for why altered PMP-22 expression may be pathophysiologically relevant in a CNS disorder such as schizophrenia.
doi:10.2478/v10134-010-0038-3
PMCID: PMC3093192  PMID: 21572910
Myelin; Peripheral myelin protein-22; Schizophrenia

Results 1-5 (5)