Этосуксимид повышает исследовательскую мотивацию и улучшает эпизодическую память в тесте распознавания нового обьекта у крыс линии WAG/Rij с генетической абсанс-эпилепсией

Abstract

In the present study, episodic memory was investigated in the novel object recognition test in WAG/Rij and Wistar rats at the age of 2 and 6 months. In order to suppress spike-wave seizure activity and depressive-like comorbidity WAG/Rij rats, at the age of 6 months, were injected ethosuximide (300 mg/kg, 14 days, i/p). Novel object recognition test consisted of 3 phases: adaptation phase, familiarization phase (two identical objects), testing session 1 (familiar and novel object 1) and testing session 2 (familiar and novel object 2). In adaptation phase, investigatory activity (number of rearings and center entries) was recorded. Recognition memory was tested with a delay of 1h (testing session 1) and 24h (testing session 2), after familiarization phase. Episodic memory was assessed using novel object recognition index. It has been found that recognition index in WAG/Rij rats, at the age of 2 months, did not differ significantly, but at the age of 6 months, it differ significantly from the corresponding measure in Wistar rats. WAG/Rij rats exhibited reduced investigatory motivation compared with Wistar rats at the age of 6 months only. A positive correlation was found between recognition index and investigatory motivation (number of unassisted rearings and center entries). Ethosuximide suppressed spike-wave seizures, increased investigatory motivation and improved episodic memory in WAG/Rij rats. Results suggest that episodic memory impairments in WAG/Rij rats are a consequence of reduced investigatory motivation as one of the symptom of depression co-morbid to absence epilepsy.