The effect of L-DOPA and L-5-hydroxytryptophan on the pentetrazole seizures in rats after lesions of the median raphe nucleus and substantia nigra.

Electrolytic lesions of the median raphe nucleus and substantia nigra markedly increased susceptibility to pentetrazole seizures in rats. L-5-hydroxytryptophan, considerably increasing the serotonin (5-HT) level in the brain, markedly inhibited the seizures and abolished the seizure-enhanced effect of lesion of the substantia nigra. L-DOPA tended to potentiate the seizures-enhancing effect produced by lesions of the median raphe nucleus. The changes in the brain 5-HT level and the intensity of pentetrazole seizures were correlated. The results indicate that the balance between neurotransmitter systems in the brain is of importance to the susceptibility to pentetrazole convulsions.