Substance P antagonists in substantia nigra are anticonvulsant.

Bilateral intranigral microinfusion of antagonist analogs of substance P significantly attenuated convulsions induced by maximal electroshock or intravenous bicuculline in rats. Infusions of substance P antagonists placed adjacent to the substantia nigra in the vicinity of the lateral hypothalamus were without anticonvulsant action. Our data indicate an as yet undescribed role for substance P antagonists in the regulation of seizure susceptibility, and provide additional evidence that decreasing the activity of substantia nigra outputs is anticonvulsant.