Abortive amygdaloid kindled seizures following microinjection of gamma-vinyl-GABA in the vicinity of substantia nigra in rats.

The effects of microinjection of a GABA-elevating substance (gamma-vinyl-GABA) in the substantia nigra were assessed on kindled convulsive seizures induced by daily appropriate amygdaloid stimulation in the rat. Bilateral administration of 20 micrograms of gamma-vinyl-GABA strongly reduced the afterdischarge duration of the seizures without significantly modifying the motor convulsions. This effect was noted 24 h after injection and lasted for up to 48 h. Administration of gamma-vinyl-GABA in structures 1.5 mm distant from the substantia nigra had no effect on kindled seizures. It is suggested that the substantia nigra may intervene in a negative feedback system that tends to suppress the paroxysmal activity initiated from the amygdala.