ANXIOGENIC-LIKE CONSEQUENCES IN ANIMAL-MODELS OF COMPLEX PARTIAL SEIZURES

Several kinds of psychiatric symptoms (anxiety, depression, schizophre nia) have been associated with epilepsies, and clinical data suggest t hat patients with seizures involving limbic structures are the most pr one to develop behavioural disorders between the seizures (i.e. interi ctally). Studying the neurobiological mechanisms that underlie these s ymptoms is difficult in humans because of different interfering factor s (e.g. psychosocial difficulties, pharmacological side-effects, lesio ns), which can be avoided in animal models. Using repetitive electrica l stimulations (kindling) or local applications of a neuroexcitotoxin in limbic structures (mainly the amygdala and hippocampus), several au thors have reported lasting changes of emotional reactivity in cats an d rats. These changes appear as anxiety-related reactions expressed as a hyperdefensiveness in the cat, or a reduction of spontaneous explor ation in tests predictive of anxiogenic effects in the rat. Some neuro plasticity processes known to develop during epileptogenesis (neuronal hyperexcitability, modulation of GABA/benzodiazepine transmission) ma y participate in these lasting changes of behaviour, especially in str uctures involved in the control of fear-promoted reactions (amygdala, periaqueductal grey matter). in addition, endogenous control systems m ay also play a critical role in the occurrence of interictal behaviour al disorders. (C) 1997 Elsevier Science Ltd.