Amygdala kindling in the rat: anxiogenic-like consequences

Patients with complex partial seizures of temporal lobe origin may experience behavioural disorders like depressive, anxiety-related or schizophrenic-like symptoms between seizures, i.e. interictally. The neural mechanisms underlying these enduring interictal disorders remain to be investigated. The aim of the present study was to examine the behavioural consequences of kindling of the basolateral nuclei of the amygdala, an animal model of limbic complex partial seizures. Animals having experienced 15 stage 5 seizures were compared to non-kindled controls in different behavioural tests performed at least seven days after the last seizure. Kindled animals showed a significant reduction of exploration of open arms in the elevated plus-maze test. In the social interactions test, they showed a decrease of non-social behaviour and an increase of immobility. No modifications were observed in kindled animals when tested in the open field, the sucrose preference or the forced swimming test. The reduction of open arm exploration in the elevated plus-maze was reversed by a pretreatment with chlordiazepoxide (2 mg/kg i.p.), a benzodiazepine anxiolytic. Finally, a similar reduction of open arm exploration was observed when animals were kindled only until a stage 3 seizure occurred. These data, along with previous studies, suggest that kindling of the amygdala has anxiogenic consequences and provide an animal model to study the neuroplasticity phenomena underlying enduring interictal disorders in humans.