Kainate-induced seizures alter protein composition and N-methyl- d-aspartate receptor function of rat forebrain postsynaptic densities

• Published in: Neuroscience Vol. 102; no. 1; pp. 65 - 74
• Main Authors: Wyneken, U, Smalla, K.-H, Marengo, J.J, Soto, D, de la Cerda, A, Tischmeyer, W, Grimm, R, Boeckers, T.M, Wolf, G, Orrego, F, Gundelfinger, E.D
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-01-2001; Elsevier
• Subjects: Animals; Biological and medical sciences; Cytoskeleton - metabolism; Disease Models, Animal; epilepsy; Epilepsy, Temporal Lobe - metabolism; Epilepsy, Temporal Lobe - physiopathology; Excitatory Amino Acid Agonists - pharmacology; glutamate receptor; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Kainic Acid - pharmacology; Male; Medical sciences; Nerve Tissue Proteins - drug effects; Nerve Tissue Proteins - metabolism; Nervous system (semeiology, syndromes); Neurology; Neurons - drug effects; Neurons - metabolism; Phosphorylation; Prosencephalon - drug effects; Prosencephalon - metabolism; Prosencephalon - physiopathology; protein kinases; Rats; Rats, Wistar; Receptors, Kainic Acid - metabolism; Receptors, Metabotropic Glutamate - metabolism; Receptors, N-Methyl-D-Aspartate - drug effects; Receptors, N-Methyl-D-Aspartate - metabolism; SAP90-PSD95 Associated Proteins; SAP90/PSD-95; Seizures - chemically induced; Seizures - metabolism; Seizures - physiopathology; Subcellular Fractions - metabolism; synapse; Synaptic Membranes - drug effects; Synaptic Membranes - metabolism; synaptic plasticity; Tyrosine - metabolism; epilepsy; SAP102, synapse-associated protein of mol. wt 102,000; CaMKII, calcium/calmodulin-dependent kinase type II; NSF, N-ethylmaleimide-sensitive fusion protein; EGTA, ethyleneglycolbis(2-aminoethyl ether)tetra-acetate; EDTA, ethylenediaminetetra-acetate; SAP90/PSD-95, synapse-associated protein of mol. wt 90,000/PSD protein of mol. wt 95,000; protein kinases; MAGuK, membrane-associated guanylate kinase homolog; mGluR, metabotropic glutamate receptor; PSD, postsynaptic density; AMPA, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate; group N, kainate-treated rats that did not develop seizures; PKC, protein kinase C; HEPES, N-2-hydroxyethylpiperazine- N′-2-ethanesulfonic acid; MAP2B, microtubule-associated protein 2B; synapse; SAP90/PSD-95; group C, saline-treated rats; TrkB, neurotrophin receptor tyrosine kinase B; glutamate receptor; group S, kainate-treated rats that developed severe seizures; nNOS, neuronal nitric oxide synthase; synaptic plasticity; NMDA, N-methyl- d-aspartate; Nervous system diseases; Rat; Epilepsy; Rodentia; Central nervous system; Glutamate receptor; Cerebral disorder; Prosencephalon; Vertebrata; Experimental disease; Mammalia; Animal; Central nervous system disease; Synaptic plasticity; Postsynaptic density; NMDA receptor; Kainic acid
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(00)00469-3

The postsynaptic density is a highly dynamic structure, which is reorganized in an activity-dependent manner. An animal model for temporal lobe epilepsy, i.e. kainate-induced limbic seizures in rats, was used to study changes in postsynaptic density composition after extensive synaptic activity. Six hours after kainate injection, the protein content of the postsynaptic density fractions from rats that developed strong seizures was increased three-fold compared to saline-treated controls. Immunoblot analysis revealed that the relative amounts of metabotropic glutamate receptor 1α,
N-ethylmaleimide-sensitive fusion protein, protein kinases C, Fyn and TrkB, as well as the neuronal nitric oxide synthase, were significantly higher in seizure-developing than in control rats. In contrast, the relative contents of the kainate receptor KA2 subunit, β-actin, α-adducin and the membrane-associated guanylate kinase homolog SAP90/PSD-95 were decreased. The relative amounts of additional postsynaptic density proteins, including α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate and
N-methyl-
d-aspartate receptor subunits, calcium/calmodulin-dependent kinase type II, casein kinase 2, tubulin, microtubule-associated protein 2B, the membrane-associated guanylate kinase homolog SAP102, and proline-rich synapse-associated protein 1/cortactin binding protein 1/Shank2 remained essentially unchanged. To assess possible changes in postsynaptic performance, postsynaptic densities were isolated from control and epileptic rats, incorporated into giant liposomes and
N-methyl-
d-aspartate receptor currents were recorded. A significant reduction in the mean conductance was observed in patches containing postsynaptic densities from animals with high seizure activity. This was due to the presence of reduced conductance levels in each membrane patch compared to control postsynaptic density preparations.
From these data, we suggest that intense synaptic activity associated with seizures modifies the composition of postsynaptic densities and has profound consequences on the function of the
N-methyl-
d-aspartate receptors present in them. This rearrangement may accompany impairment of synaptic plasticity.