title: A comparison of recurrent inhibition and of paired-pulse facilitation in hippocampal slices from normal and genetically epileptic mice.
abstract: Tottering mice exhibit inherited generalized epilepsy of the 'absence' type. In hippocampal slices from these mutant mice studied in vitro, pairing an alvear antidromic stimulus to an orthodromic one revealed a strong recurrent inhibition (RI) of CA1 pyramidal neurons. RI was maximal at 10 ms inter-pulse interval (IPI 70% decrease of population spike, PS) gradually decreasing to 15% at 320 ms IPI. At 10 ms IPI it shifted the input/output curves to the right and decreased maximum PS. In the group of slices from epileptic mice the early part of RI (2.5-60 ms) was indistinguishable from that of normal mice, with respect to both its strength and its liability to activity-dependent decrement induced by a train of antidromic stimuli (8 s, 5 Hz). However, the delayed part (80-320 ms) was slightly stronger in the epileptic group. Also in this group only the train of antidromic pulses caused a significant and lasting decrease in the unconditioned orthodromic PS. Paired-pulse facilitation was equally strong in the 2 groups of slices. It is concluded that mechanisms underlying epileptogenic hyperexcitability in the tottering mutant may not include a failure of inhibition, at least in the CA1 area of the hippocampus. On the contrary some inhibitory mechanisms may be stronger.
authors.affiliation: Department of Physiology, University of Patras Medical School, Greece.
authors.forename: G
authors.initials: G
authors.lastname: Kostopoulos
authors.forename: G
authors.initials: G
authors.lastname: Antoniadis
mesh_terms: D000818:Animals; D004558:Electric Stimulation / Q000379:methods*; D004827:Epilepsy / Q000235:genetics / Q000503:physiopathology*; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008818:Mice, Neurologic Mutants; D009433:Neural Inhibition / Q000502:physiology*; D012008:Recurrence; D013997:Time Factors