Postseizure inhibition of kindled seizures

Abstract

Rats were kindled until each periodic, bipolar, amygdaloid stimulation reliably elicited and afterdischarge and a generalized motor seizure. The inhibitory effects of one amygdaloid stimulation (antecedent stimulation) on the afterdischarges and motor seizures typically produced by the next (test stimulation) were studied in a series of experiments. Levels of antecedent stimulation which themselves elicited afterdischarges and motor seizures produced marked inhibitory effects which dissipated in approximately 90 min, whereas levels of antecedent stimulation which elicited local afterdischarges but no motor seizures had only mild inhibitory consequences. Regardless of their intensity, stimulations which evoked no epileptic responses themselves did not inhibit the responses to subsequent test stimulations. The inhibitory effect of a series of antecedent stimulations was more complex than that produced by a single stimulation. A series of 19 kindled motor seizures was elicited by amygdaloid stimulations applied at 1.5-h intervals without any indication of inhibitory effects; however, the next day the response to a single amygdaloid stimulation was almost completely suppressed. This marked inhibitory effect dissipated gradually during the next 5 days.