Effects of chronic haloperidol treatment on amygdaloid seizure generation in cats.

We evaluated the effect of chronic haloperidol treatment (0.5-2 mg/kg/day, 21 day) on amygdala-generating seizures using a kindling procedure induced by low frequency electrical stimulations. The number of stimulating pulses required for triggering of epileptic afterdischarge (pulse-number threshold; PNT) is the indicator of the seizure generating threshold. A PNT decrease occurred, followed by a PNT increase toward the pre-treatment level during high-dose, chronic haloperidol treatment. A PNT increase occurred, followed by a PNT decrease toward the pre-treatment level during the withdrawal period after the high-dose treatment. A decrease of the triggered seizure duration occurred during the high-dose treatment. These results indicate that a transient decrease of seizure generating threshold occurs during chronic haloperidol treatment, and withdrawal of the drug is followed by what appears to be a rebound phenomenon. We suggest that this effect might be related to the antipsychotic potency and associated neurochemical changes known to be caused by chronic haloperidol treatment.