Reassessing anhedonia in Genetic Absence Epilepsy: Sucrose preference unaltered by spike-wave discharges in WAG/Rij rats.

Abstract

Anhedonia, characterized by reduced pleasure or interest, is linked to various neurological disorders, including genetic epilepsies. Previous studies in genetic rat models of absence epilepsy, such as WAG/Rij rats, have reported anhedonia-like behaviors. Here, we hypothesize that these behaviors depend on experimental factors rather than epilepsy itself. To test this, we conducted sucrose preference tests in WAG/Rij rats using different concentrations (2 % and 20 %), fasting durations (0 and 23 h), and test lengths (1 and 48 h). Rats underwent non-invasive electroencephalographic examination, which revealed typical 8-10 Hz spike-wave discharges (SWD) and a hallmark of absence epilepsy. In Experiment 1 (2 % sucrose), 59 symptomatic and 31 asymptomatic rats were tested at 6 and 12 months. In Experiment 2 (20 % sucrose), 34 rats were tested at 6 months. Surprisingly, there were no significant differences in sucrose preference or consumption between symptomatic and asymptomatic rats, indicating that absence epilepsy in WAG/Rij rats does not cause anhedonia. After a 23-h fast, female rats showed a lower preference for 20 % sucrose than males, suggesting that fasting conditions might introduce stress and metabolic differences that affect males and females differently. Both the 2 % and 20 % sucrose preference tests showed that symptomatic WAG/Rij rats did not exhibit anhedonia and had similar preferences to asymptomatic rats, regardless of concentration or fasting conditions. These findings challenge previous assumptions and emphasize the importance of considering methodological factors when interpreting rodent behavior.