Bilateral symmetrical spike-and-wave discharges (SWDs) with a frequency of 7–11 Hz, recorded in WAG/Rij rats with genetically determined absence activity, serve as electroencephalogram (EEG) hallmarks of this activity. Absence epilepsy proceeds without motor manifestations and is accompanied by freezing, and twitching of the vibrissae and head in rodents. Krushinsky-Molodkina (KM) rat strain with a genetically determined predisposition to audiogenic epilepsy (AE) is considered a seizure model of reflex epilepsy. AE is characterized by the occurrence of tonic-clonic seizures provoked by an intense auditory stimulus. Approximately 20–50% of WAG/Rij rats exhibit a predisposition to AE, although with a less pronounced audiogenic seizure proneness compared to KM strain rats. Recent studies of the electrical brain activity in KM rats have shown the presence of absence-like activity on the EEG. This study aimed to compare SWD characteristics in three groups of rats with varying predispositions to AE: (1) WAG/Rij-nonAGS (n = 10)—WAG/Rij rats insensitive to a sound provocation, (2) WAG/Rij-AGS (n = 12)—WAG/Rij rats predisposed to AE, and (3) KM rats (n = 18) with a maximum audiogenic seizure proneness. EEG recording was performed using bipolar electrodes implanted into the somatosensory cortex. A comparative analysis of spectral power, number, total and average duration of SWDs was conducted in two subpopulations of WAG/Rij rats (WAG/Rij-nonAGS, WAG/Rij-AGS) and KM rats with AE and absence-like EEG activity. Comparison between two subpopulations of WAG/Rij rats showed a significant increase in the number, as well as average and total duration, of SWDs in WAG/Rij-AGS compared to WAG/Rij-nonAGS. SWDs in KM rats with a fundamental frequency of 8.7 Hz were suppressed by ethosuximide and accompanied by behavioral symptoms characteristic of absence epilepsy. Absence epilepsy exacerbated in the following order: WAG/Rij-nonAGS → WAG/Rij-AGS → KM. Therefore, the severity of absence seizures increases in parallel with the enhancement of audiogenic brain reactivity, which may indicate the exacerbating role of the convulsive component in the structure of mixed epilepsy.
Kuzhuget et al. (2026) studied this question.