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.