| The purpose of our present work was to investigate the neural network and its cellular electrophysiological mechanisms of hippocampal epileptic network reconstructed ipsilaterally or contralaterally by acute tetanization (60Hz, 2s, 0.4~0.6mA) of the right posterior dorsal hippocampus (ATPDH). The experiments were performed on 68 male Sprague Dawley rats, weighed 150~250g. About ten ATPDH trains were used at an interval of 10 minutes to estabolish epilepsy model. Hippocampal EEG and single unit discharges were simultaneously recorded from ipsilateral or contralateral anterior dorsal HPC. Hippocampal network seizure-like activities and its power spectrum were analyzed. The neuronal firing patterns and its interspike interval (ISI) spot distributions were also analyzed. Results: (1) The CA1 single neuronal firing rate was inhibited ipsilaterally or contralaterally after the ATPDH, and it showed synaptic transmission plasticity following a series of trains. (2) The latency of the primary unit afterdischarges was shorter on ipsilateral side and its ISI spots distributed a "head" and "tail" shape. But it was longer on the contralateral side and the ISI spots distributed a "tail" and "head" shape. (3) Primary unit afterdischarges were ipsilaterally synchronized with hippocampal EEG seizure-like oscillations at 80Hz. (4) Status epilepticus of CA3 neural network was contralaterally synchronized with epilepsy-related subicular single neuronal activities for several hours. It implies an obvious cellular electrophysiological mechanism during electrogenic hippocampal epileptic network reconstruction. The hippocampal epileptic network reconstruction across two hemispheres might be related to ATPDH-induced contralateral hippocampal epilepsy genesis, development and propagation.
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