TYROSINE PHOSPHORYLATION IS INCREASED IN THE RAT HIPPOCAMPUS DURING THE STATUS EPILEPTICUS INDUCED BY PILOCARPINE

Phosphorylation of tyrosine residue in proteins is an important modula tory process for membrane transduction and cell signaling and for seve ral cellular functions. The concentration and distribution of phosphot yrosine proteins were analyzed in the hippocampi of rats in the model of epilepsy induced by pilocarpine using Western blotting and immunohi stochemistry. The concentration of several phosphotyrosine proteins in creased during status epilepticus, During the seizure-free period and the chronic period of this epilepsy model, the hippocampi of rats did not exhibit changes in the expression of these proteins. Immunohistoch emistry showed an increased immunoreactivity throughout the hippocampa l formation of rats 1 h after states epilepticus that was acutely indu ced by pilocarpine, Animals killed after 3 h of states epilepticus sho wed an increased expression of phosphotyrosine in the hippocampal hilu s and CA3 regions. After 5 h of states epilepticus, phosphotyrosine im munoreactivity persisted only in the CA3 region. After 12 h of status epileptices, the hippocampal formation exhibited a normal phosphotyros ine immunostaining, showing that the increased expression of these pro teins is related to the acute phase and that several intracellular eve nts could undergo modifications during the status epilepticus induced by pilocarpine, (C) 1998 Elsevier Science Inc.