Abstracts

Rationale: Temporal lobe epilepsy (TLE) is the most common adult epilepsy syndrome although one-third of patients remain refractory to current pharmacological treatment. In addition, TLE is commonly accompanied by neuropsychiatric and neurocognitive comorbidities including anxiety, depression and learning deficits. Given recent animal studies highlighting enhanced seizure susceptibility following stress, it was of interest to examine the neuroprotective capacity of ‘positive experiences’ created using environmental enrichment (EE). Methods: Male Wistar rats were randomly allocated into one of two housing conditions at weaning: EE (large plastic cages containing running wheels, assorted bedding and toys) or Impoverished Housing (IH; standard laboratory cages with sawdust bedding only). Bipolar electrode implantation into the left amygdala was performed at P63, followed by rapid amygdala kindling at P70. The development of epilepsy was scored using the Racine scale of behavioural seizures with rats deemed fully-kindled after five class V seizures. The Elevated Plus Maze (EPM) and Morris Water Maze (MWM) behavioural tests were conducted to assess anxiety and spatial learning, respectively. Results: EE delayed the time-course of seizure progression, with enriched rats (n=16) requiring a significantly greater number of kindling stimulations to elicit the first class V seizure and to reach a fully-kindled state compared to IH rats (n=13; p<0.05). EE also reduced anxiety-like behaviour in the EPM (EE: n=27, IH: n=23; p<0.05) and facilitated superior performance in the MWM (EE: n=16, IH: n=13; p<0.05). Conclusions: Our data demonstrates a beneficial effect of prolonged EE on vulnerability to limbic epilepsy, co-morbid anxiety and neurocognitive function.