Role of the amygdala in development of hippocampal kindling in the rat.

The influence that the amygdala may exert on the development of hippocampal kindling was investigated using three different approaches: (i) after uni- or bilateral amygdalectomy by thermocoagulation, (ii) after prestimulation of the amygdala until the appearance of masticatory movements, and (iii) after increasing the GABA concentration in the amygdala with gamma-vinyl GABA. Hippocampal kindling was not significantly modified in amygdalectomized animals. On the contrary, prestimulation of the ipsilateral amygdala facilitated the subsequent hippocampal kindling. Finally, microinjection of gamma-vinyl GABA in both amygdalae either reduced the seizures to a prekindled level or strongly delayed the appearance of the motor signs of kindling. It is suggested that hippocampal kindling may develop preferentially through the amygdala.