Abstracts

Epilepsy patients commonly suffer from affective co-morbidities, particularly anxiety and depression. This has widely been thought to be a consequence of the epileptic process, but recent evidence suggests there could be a common causal link. This study investigates whether the GAERS (Generalised Absence Epileptic Rats from Strasbourg) strain of rats, a phenotypic animal model of generalised absence epilepsy, also display behavioral abnormalities, and attempts to determine whether these behaviors are present prior to the development of absence seizures., Mixed gender GAERS rats were compared with Non-Epileptic Controls in neurobehavioral tests for anxiety (elevated plus maze) and depression (sucrose-preference test). Comparisons were made at 7 or 13 weeks, the equivalent neurodevelopmental age of adolescence in a rat, and also before and after the development of seizures., GAERS rats showed increased anxiety in the elevated plus maze at both 7 and 13 weeks of age compared with NEC rats, as evidenced by a significantly lower number of open arm entries (at 7 weeks: 3.14 [plusmn] 0.53 entries (n=14) vs 7.90 [plusmn] 1.01 (n=20); at 13 weeks: 4.67 [plusmn] 1.03 entries (n=15) vs 6.09 [plusmn] 0.73 (n=11) - two-way ANOVA, p=0.0019). This strain of rats also displayed a significantly reduced preference for sucrose drinking water (at 7 weeks: 3.18 [plusmn] 0.66ml (n=11) vs 6.67 [plusmn] 0.88ml (n=3); at 13 weeks: 3.00 [plusmn] 0.84ml (n=5) vs 4.83 [plusmn] 0.63ml (n=12) - two-way ANOVA, p=0.0054), indicating an anhedonic state and suggestive of a depressive phenotype., This study provides strong evidence that GAERS rats, when compared with non-epileptic controls, display anxious and depressive behaviors which are present to the onset of absence seizures. This suggests that affective disorders may not be a consequence of seizures, and also raises the possibility that there may be a common neurodevelopmental causality which predisposes humans to both affective disturbance and epilepsy., (Supported by an NHMRC project grant (400088), and a NARSAD Independent Investigator Award (TOB).)