The lower expression of parvalbumin in the primary somatosensory cortex of WAG/Rij rats may facilitate the occurrence of absence seizures

Abstract

Absence epilepsy (AE) is classified as a genetic generalized epilepsies. WAG/Rij strain of rats are regarded one of the most validated models of absence epilepsy. Studies point out the existence of hyperexcitable focus in somatosensory cortex of these rats, which has been attributed to the deficits in the GABAergic system. In the current study, we studied the changes of calcium binding proteins (CaBPs) in somatosensory cortex (S1) of the 2 and 8 month-old WAG/Rij rats and their age-matched Wistar Albino controls by investigating the expression levels of CaBPs (calbindin, calretinin and parvalbumin) in western blotting. Since WAG/Rij rats showed the low expression level of parvalbumin (PV) in western blots in comparison to Wistar Albino rats, we selectively investigated the number of PV positive neurons using the immunofluorescence staining method in order to confirm this decrement in the perioral region of somatosensory cortex (S1po). The most critical finding of this study was the age- independent reduction in the expression level of PV in the somatosensory cortex of epileptic rats as demonstrating western blotting. Nevertheless, no significant difference was found among numbers of PV + neuron in the S1po region by immunofluorescence staining concerning both of age and strain dependency. These results suggest that the disruption in the activity of the PV-expressing GABAergic interneurons might be involved in the generation of rather than the age-dependent increase in the SWDs in WAG/Rij rats.