Compensatory Changes in the Brain Dopaminergic System of WAG/Rij Rats Genetically Predisposed to Absence Epilepsy.

Involvement of the brain dopaminergic system in the age-related dynamics of absence epilepsy in WAG/Rij rats was examined by histological, immunohistochemical, and electrophysiological (EEG) methods. We revealed reduced expression of dopamine receptors in various brain structures prior to first manifestations of the disease (at the age of 1-3 months), reduced density of neurons in the center of nigrostriatal system (substantia nigra pars compacta) in 10-month-old rats in comparison with 1-month-old rats, and positive correlation between neural density in the substantia nigra and intensity of epileptic activity in EEG. It is hypothesized that loss of dopaminergic neurons and reduced nigrostriatal dopaminergic innervation of the brain could prevent the development of absence epilepsy in WAG/Rij rats.