Interictal discharges in the hippocampus of rats with long-term pilocarpine seizures.
Systemic administration of pilocarpine to adult rats induces an acute status epilepticus followed by spontaneous recurrent seizures after a 1-2-week silent period. We recorded field potentials in hippocampal slices obtained from rats with spontaneous recurrent seizures after pilocarpine-induced status. The frequency of the interictal discharges induced in these slices by 4-aminopyridine (4AP) was reduced and their duration was increased. Cutting the Schaffer collaterals caused interictal discharges in CA1 to disappear in normal rats and in rats 3 weeks after pilocarpine-induced status. However, 12 weeks after pilocarpine, these discharges remained in CA1 after such a cut but occurred at a lower frequency. These findings show that in rat hippocampi with a lesion similar to that of human Ammon's horn sclerosis some electrophysiological features of 4AP-induced interictal discharges are altered in comparison to those induced in normal hippocampi.
Montreal Neurological Institute, Quebec, Canada.
T
T
Nagao
M
M
Avoli
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P
Gloor
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D002908:Chronic Disease; D004594:Electrophysiology; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D010862:Pilocarpine; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000139:chemically induced / Q000503:physiopathology*
D010862:Pilocarpine; D015761:4-Aminopyridine