Morphological changes in the substantia nigra pars reticulata of the mice during kindling

Substantia nigra pars reticulata (SNpr) has been implicated in modulation, propagation and cessation of seizures. This study aimed to determine whether structural changes occur in SNpr during kindling. Male mice were randomly divided into four groups including early and late-phase kindled groups and their time-matched controls. Kindling was induced by every other day administration of a subconvulsive dose of PTZ (40 mg/kg, i.p.). The first occurrence of seizure behaviors was used to categorize the early and late phases of kindling. There was no significant difference in the volume of SNpr between the early- and late-phase kindled groups. The diameter of SNpr was significantly increased in the early phase group and decreased in the late phase group as compared to their matched controls (p < 0.05). Reduced neural cells and increased dead cell numbers were observed in the SNpr of the late-phase group in comparison to its control group (p < 0.05). These findings suggest that SNpr is a sensitive and vulnerable structure involving seizure propagation in the processes of epileptogenesis.