The effects of L-DOPA and transcranial magnetic stimulation on behavioral reactions in kindled rats.

Acute experiments were performed on rats to produce a model of chronic epileptic activity--pharmacological kindling by repeated doses of picrotoxin (1.0-1.2 mg/kg, i.p.). During the early period following kindling (24 h from the last dose of epileptogen), animals showed decreases in measures of investigative behavior as measured in an open field test, along with reductions in sexual and feeding behavior. The severity of these impairments had decreased by two weeks from the last picrotoxin dose. Both treatment with L-DOPA (100 mg/kg, i.p.) and transcranial magnetic stimulation (20 impulses with induction, peak 1.5 T) were accompanied by increases in measures of investigative, sexual, and feeding behavior in the animals, suggesting that mechanism of action of transcranial magnetic stimulation in relation to kindling-induced behavioral abnormalities is mediated by activation of the dopaminergic system of the brain.