The role of the substantia nigra pars reticulata anterior in amygdala-kindled seizures

Background: It has been reported that the substantia nigra pars reticulata (SNr) is of regional differences and involved in the initiation, generalization, and cessation of seizures. However, neuropharmacological investigations into the role of the SNr anterior (SNr(a)) in temporal lobe epilepsy (TLE) have been inconsistent, suggesting that electrophysiological investigations are needed to elucidate the role of the SNr(a) in TLE. Methods: Local field potentials (LFPs) and single-unit activities were simultaneously obtained from the basolateral amygdala (BLA) and the SNr(a) in amygdala-kindled mice. The electrophysiological characteristics of the neuronal activities in the BLA and SNr(a) were investigated. Directionality index was used to measure information flow between LFPs in the two areas during kindled seizures. The effects of electrical lesion of the SNr(a) on the kindled seizures were analyzed in fully-kindled mice. Results: The information flow was predominantly from the SNr(a) to the BLA during the clonic-like periods of stage 5 seizures, but this phenomenon was not found during other kindled seizures. In fully-kindled mice, SNr(a) lesions facilitated the kindled seizures. After lesions were inflicted, the afterdischarge durations and clonic-like periods of stage 5 seizures increased significantly. Conclusion: The electrophysiological and lesion results show that the SNr(a) may play an anti-convulsant role in amygdala-kindled seizures.