Tyrosine phosphorylation is increased in the rat hippocampus during the status epilepticus induced by pilocarpine

Phosphorylation of tyrosine residue in proteins is an important modulatory process for membrane transduction and cell signaling and for several cellular functions. The concentration and distribution of phosphotyrosine proteins were analyzed in the hippocampi of rats in the model of epilepsy induced by pilocarpine using Western blotting and immunohistochemistry. The concentration of several phosphotyrosine proteins increased 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. Immunohistochemistry showed an increased immunoreactivity throughout the hippocampal formation of rats 1 h after status epilepticus that was acutely induced by pilocarpine. Animals killed after 3 h of status epilepticus showed an increased expression of phosphotyrosine in the hippocampal hilus and CA3 regions. After 5 h of status epilepticus, phosphotyrosine immunoreactivity persisted only in the CA3 region. After 12 h of status epilepticus, the hippocampal formation exhibited a normal phosphotyrosine immunostaining, showing that the increased expression of these proteins is related to the acute phase and that several intracellular events could undergo modifications during the status epilepticus induced by pilocarpine.