Zif268 and Fos-like immunoreactivity in tetanus toxin-induced epilepsy: reciprocal changes in the epileptic focus and the surround |
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Authors: | Fengyi Liang Edward G. Jones |
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Affiliation: | aDepartment of Anatomy and Neurobiology, University of California, Irvine, CA 92697-1280, USA;bLaboratory for Brain Structure and Function, Frontier Research Program, Institute of Physical and Chemical Research (Riken), 2-1 Hirosawa, Wako City, Saitama 351-01, Japan |
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Abstract: | Altered gene expression for a number of molecules has been suggested as one of the underlying mechanisms of epileptogenesis. Changes in expression of the immediate early genes, zif268 and c-fos, were investigated in chronic focal epilepsy induced by tetanus toxin (TT, 20–35 ng) injected in the rat motor cortex. Most rats injected with TT and perfused on postoperative day 5, 7 or 14 had recurrent focal seizures after a latent period of 4–13 days, and showed enhanced Zif268 immunoreactivity in a cluster of neurons at the injection site, as well as reduced Zif268 immunoreactivity in a distinct cortical zone around this cluster. C-fos or Fos-related immunoreactivity was decreased over widespread areas of frontoparietal and piriform cortex in epileptic rats, except for a focus at the injection site which, in most cases, showed increases in Fos-like immunoreactivity. Some epileptic rats showed increased Zif268 immunoreactivity in neurons of the ipsilateral ventral lateral and central lateral thalamic nuclei and increased Zif268 and Fos-like immunoreactivity in the pontine nuclei. Rats perfused before onset of seizures, showed no overt changes other than a slight decrease in Zif268 and Fos-like immunoreactivity at the injection site. The reciprocal changes in Zif268 immunoreactive neurons in the epileptic focus and the immediate surround parallel changes in gene expression for a number of molecules important in epileptogenesis and suggest a state of functional disconnection of the epileptic focus from other cortical areas that may contribute to the development and maintenance of focal epilepsy. |
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Keywords: | Epilepsy Motor cortex Immediate early gene c-fos zif268/egr-1 Tetanus toxin Activity-dependent gene expression |
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