Showing papers on "Epileptogenesis published in 1975"

Kindling: secondary epileptogenesis, sleep and catecholamines.

Abstract: Seizure development and transference phenomenon were investigated in hippocampal and amygdaloid kindled cats. The behavioral and electrographic findings during the kindling procedures showed that motor seizure development in hippocampal seizures occurred with the emergence of independent discharging in the amygdala, globus pallidus and contralateral hippocampus. Furthermore, secondary site convulsions developed upon the first stimulation of these structures in the hippocampal group but only after over a month of hippocampal stimulation in the amygdaloid group. It was, therefore, concluded that role of the amygdala and globus pallidus in hippocampal seizure development was more essential than that of hippocampal stimulation in amygdaloid seiqure development. The common findings between the hippocampal and amygdaloid kindled animals were the systematic progression to seizures, the all-or-nothing nature of the electrical response and the relative permanency of the seizure susceptibility. Seizure susceptibility increased during slow wave sleep and decreased during REM sleep. These latter findings were examined with preliminary data of brain bioassays of catecholamines.

Secondary epileptogenesis in frog forebrain: effect of inhibition of protein synthesis.

Abstract: Secondary epileptogenesis was induced in the hippocampal cortex of the paralyzed bullfrog by means of localized, unilateral, intermittent electrical stimulation (kindling). Stimuli were designed to yield a brief but definite after-discharge. In control animals a progressive increase in after-discharge duration occurred at the 1 degree (stimulated) site and then at the 2 degrees site (contralateral hippocampus). Spontaneous epileptiform potentials (SEP's) occurred between stimuli, eventually independently on both sides. Cycloheximide (50 mg/kg) caused 88-99% reduction in protein synthesis, measured by 14C-leucine incorporation into brain protein. Cycloheximide-treated animals revealed no evidence of progressive prolongation of after-discharge duration when subjected to the kindling procedure (p = 0.1205 X 10(-7)). SEP's were reduced in the cycloheximide-treated animals, and confined to 1 degree hemisphere (p = 0.6 X 10(-10)). Since cycloheximide did not disturb normal electrogenesis or disrupt the after-discharges, this experiment distinguishes processes dependent upon electrical events from those requiring macromolecular synthesis. Protein synthesis seems critical to the emergence of spontaneous and autonomous epileptiform behavior of neural aggregates.

Hippocampal seizure and secondary epileptogenesis in the "kindled" cat preparations.

Abstract: The behavioral, electrographic and transference characteristics were investigated in hippocampal kindled cats. All animals developed generalized convulsions following daily hippocampal stimulation (mean 51.8 days). A distinct sequence of behavioral events was observed prior to the seizure and classified into six stages. Motor seizure manifestations appeared along with the emergence of an entirely independent after-discharge and interictal discharge in the bilateral globus pallidus (GP) and amygdala (AM). Secondary site convulsions were triggered with initial stimulation in the GP, contralateral dorsal hippocampus and in most AM sites. This finding suggests that after the primary site was kindled, these previously unstimulated secondary structures attained a response potency equal to that of the primary site. Furthermore, the "all-or nothing" response was confirmed both in the primary and secondary site convulsions.