Electrical stimulation of the substantia nigra pars reticulata (SNr) suppresses chemically induced neocortical seizures in rats.

Deep brain stimulation is an alternate treatment strategy for intractable epilepsy. The effects of low- and high-frequency electrical stimulation to the substantia nigra pars reticulata (SNr) of different sides on chemically induced neocortical seizure were investigated in the present study. After neocortical seizure was induced by ferric chloride injection into the left sensorimotor cortex, SNr was stimulated ipsilaterally, contralaterally, or bilaterally at frequencies of 130 or 20 Hz in rats. Unilateral and bilateral stimulation at 130 Hz reduced significantly the number of seizures but not their duration. Ipsilateral, contralateral as well as bilateral stimulations at 130 Hz were all equally effective, producing reductions in seizures of 63.62, 77.84, and 68.74% compared with the control group, respectively. Electrical stimulation at 20 Hz did not reduce the number or duration of seizures regardless of the side stimulated. Both unilateral and bilateral stimulations of SNr at 130 Hz can suppress ictogenesis in the cortex, but electrical stimulation at 130 or 20 Hz does not reduce the severity of individual seizures. The frequency of stimulation is paramount in suppressing neocortical seizures in which DBS at least targets SNr.