The neuronal density in the rostral pole of substantia nigra pars compacta in Wistar Albino rats from Rijswijk rats: A link to spike-wave seizures.

This study aimed to investigate the role of the nigrostriatal dopaminergic system in the modulation of absence epilepsy. Immunochemical analysis of the rostral pole of the substantia nigra pars compacta (SNpc) was conducted on 13 adult male Wistar Albino rats from Rijswijk rats. The rostral pole of the SNpc included the dorsal and lateral parts. The neuronal density in the dorsal part was higher than in the lateral part. The ratio of dopaminergic to non-dopaminergic neurons in the lateral part of the SNpc was 1:1, while in the dorsal part, it was around 1.9:1. All rats exhibited spontaneous spike-wave discharges (SWDs) on their electrocorticograms. SWDs are known to be a hallmark of absence seizures in both human patients and rat models. In this study, we found that the number and duration of SWDs were negatively correlated with dopaminergic and non-dopaminergic neurons only in the lateral part of the SNpc. However, in the dorsal part of the SNpc, no correlations were found between neuronal density and the severity of absence epilepsy. Our findings suggest that the lateral SNpc may be involved in modulating the severity of absence epilepsy in genetically prone subjects. This contributes to a better understanding of the role of the nigrostriatal dopaminergic system in the absence of epilepsy.