Catecholamines and pinealectomy-induced convulsions in the gerbil (Meriones unguiculatus)

Within three hours after surgery nine out of ten pineal-ectomized gerbils will convulse; dopamine (DA) levels in the telencephalon of the gerbils do not change after pinealectomy (PX), however, norepinephrine (NE) concentrations decrease in the telencephalon from 1-12 hours after PX (Philo and Reiter, 1980). Administration of L-dihydroxyphenylalanine (L-DOPA, 50 mg/kg) will prevent the convulsions and maintain normal levels of norepinephrine. Administration of alpha-methyl-p-tyrosine (alpha MPT, 250 mg/kg), a tyrosine hydroxylase inhibitor, increases the number of convulsions. Injections of L-DOPA counter the facilitatory actions of alpha MPT on PX-induced convulsions. Studies with the monoamine oxidase inhibitor pargyline indicate a decrease in production of norepinephrine after PX in the gerbil. The diminished levels of neurotransmitter apparently facilitate the onset of convulsions caused by the epileptogenic stimulus of PX.