An evidence of 'post-seizure excitation' in feline-kindled seizures

Effects of chronic treatment with haloperidol and methamphetamine on hippocampal kindled seizures in the cat

We assessed the effects of chronic treatment with haloperidol (0.5-2 mg/kg/day, p.o., 17 days) and methamphetamine (1-2 mg/kg/day, p.o., 17 days; 4 mg/kg/day, p.o. 9 days) on hippocampal kindled seizures using a kindling procedure with low-frequency (about 3 Hz) electrical stimulation in cats. The number of stimulating pulses required to trigger epileptic afterdischarge (pulse-number threshold, PNT) was considered an indicator of seizure threshold. Haloperidol, 0.5 and 1.0 mg/kg, reduced the duration of epileptic afterdischarge (afterdischarge duration, ADD) without affecting PNT, and 2.0 mg/kg strongly reduced PNT and ADD. Methamphetamine, 2.0 mg/kg, reduced PNT and ADD, and 4.0 mg/kg preferentially reduced PNT. The effects of the two drugs on hippocampal kindled seizures were found to be partially opposite to those on amygdala kindled seizures, suggesting the different response of these limbic structures to dopamine receptor manipulation.

Effects of anticonvulsants on hippocampus-generating seizures

Acute effects of 4 anticonvulsants on hippocampal kindled seizures induced with about 3 Hz electrical stimulations were assessed in cats. The number of stimulating pulses required for the triggering of epileptic afterdischarge (pulse-number threshold, PNT) was used as the indicator for the seizure threshold. Duration of afterdischarge (ADD), ictal and interictal behaviors and serum drug levels were also recorded. PB produced a PNT-increase more prominently than an ADD-decrease with seizure stage regression. PHT produced only a proconvulsive effect by decreasing PNT. CBZ also produced a proconvulsive effect by decreasing PNT at a low dose, and decreased PNT and ADD simultaneously at a high dose. Conversely VPA increased PNT and ADD simultaneously. These results were discussed comparing mainly with a previous study of amygdala-generating seizures.

A biphasic change of afterdischarge threshold during the kindling process

Cats were stimulated in the ventral hippocampus with low-frequency (about 3 Hz) square wave pulses. All subjects were kindled until generalized convulsion occurred. During the kindling process, the number of stimulating pulses required for the provocation of afterdischarge (AD), which was used as an indicator of AD threshold, decreased suddenly in the initial stage and increased gradually in the late stage. We consider this phenomenon to be important in deepening the understanding of seizure generation.