Abstract
Double intraperitoneal injections of methylazoxymethanol (MAM) in pregnant rats induce developmental brain dysgenesis with nodular heterotopia similar to human periventricular nodular heterotopia (PNH) and composed of hyperexcitable neurons. Here we analyzed the NMDA receptor complex and associated proteins in the heterotopic neurons of 2- to 3-month-old MAM-treated rats by means of a combined immunocytochemical/molecular approach. Our data demonstrated a clear reduction of p286-active form of alphaCaMKII and a selective impairment of both the targeting and the CaMKII-dependent phosphorylation of NR2A/B subunits in the postsynaptic membranes of the MAM-induced heterotopia. The reduced NR2A/B immunofluorescence of the cellular membrane was not due to reduced expression since it was decreased only in postsynaptic fractions but not in the homogenate. NMDA-NR1 and AMPA-GluR2/3 subunits, as well as PSD-95 and total alphaCaMKII protein levels, were not affected in MAM-treated rats, thus revealing that the overall composition of the postsynaptic fraction was not altered. These data clearly suggest that the molecular organization of the NMDA/alphaCaMKII complex is selectively altered in the postsynaptic compartment of heterotopic neurons. This alteration can play a role in determining the hyperexcitability of brain heterotopia in MAM rats as well as in human patients affected by PNH.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Animals, Newborn
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Autoradiography / methods
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Blotting, Western
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Calcium-Calmodulin-Dependent Protein Kinase Type 2
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism
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Carcinogens / toxicity
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Cell Membrane / metabolism
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Cell Membrane / pathology
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Cerebral Cortex*
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Choristoma / chemically induced
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Choristoma / metabolism
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Choristoma / pathology*
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Cloning, Molecular / methods
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Disease Models, Animal
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Disks Large Homolog 4 Protein
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Female
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Hippocampus / metabolism
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Hippocampus / pathology
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Humans
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Immunohistochemistry
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Intracellular Signaling Peptides and Proteins
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Male
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Matched-Pair Analysis
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Membrane Proteins
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Methylazoxymethanol Acetate / analogs & derivatives*
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Methylazoxymethanol Acetate / toxicity
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Microscopy, Confocal / instrumentation
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Microscopy, Confocal / methods
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Nerve Tissue Proteins / metabolism
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Peptide Fragments / immunology
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Peptide Fragments / metabolism
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Phosphorylation
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Pregnancy
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Rats
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Receptors, AMPA / metabolism
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Receptors, N-Methyl-D-Aspartate / classification
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Receptors, N-Methyl-D-Aspartate / metabolism*
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Subcellular Fractions / metabolism
Substances
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Carcinogens
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Disks Large Homolog 4 Protein
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Dlg4 protein, rat
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Intracellular Signaling Peptides and Proteins
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Membrane Proteins
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Nerve Tissue Proteins
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Peptide Fragments
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Receptors, AMPA
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Receptors, N-Methyl-D-Aspartate
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glutamate receptor ionotropic, AMPA 3
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postsynaptic density proteins
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Methylazoxymethanol Acetate
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Calcium-Calmodulin-Dependent Protein Kinase Type 2
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Calcium-Calmodulin-Dependent Protein Kinases
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methylazoxymethanol
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glutamate receptor ionotropic, AMPA 2