[Reduction of the number of neurons in substantia nigra (Pars compacta) positively correlates with a reduction of seizure activity in WAG/Rij rats].

In WAG/Rij rats with a genetic predisposition to absence epilepsy, age-related dynamics of seizure activity in the frontal EEG was studied. In parallel, cellular content in substantia nigra was analyzed at the age of 1 and 10 months. In 10-months animals, the number of neurons in substantia nigra showed a profound decrease, whereas the number of glial calls increased. In parallel to that, the incidence of epileptic discharges and their duration significantly increased between 5 and 9 months of age. Positive correlations were revealed between the incidence of epileptic discharges and the number of neurons in substantia nigra suggesting that animals with lower number of neurons in SN expressed fewer absence seizures, and vice versa. It was suggested that reduction of neurons in substantia nigra is an adaptive process to prevent progressive development of absence seizures.