Specificity of Brain Structures Sensitive to Initiating Nerve Agent‐Induced Seizures

Abstract

Seizures not only complicate the treatment of nerve agent poisoning, but can also lead to extensive brain damage if uncontrolled. An understanding of the brain structures that initiate seizure activity would be beneficial in identifying targets for therapeutic intervention following nerve agent exposure. This study identified brain structures within the forebrain and parahippocampal regions sensitive to initiating nerve agent‐induced seizure activity and determined whether this sensitivity was ubiquitous throughout each structure. Rats were surgically prepared to record brain electroencephalographic (EEG) activity and implanted bilaterally with guide cannulae toward a designated area of the brain. On the day of the experiment, animals were injected bilaterally with 1 microliter (μl) VX (0.88 μg) through an injection cannula inserted into the guide cannulae and continuously monitored for EEG seizure activity. The amygdala, and the endopiriform, piriform, and rhinal cortices, were all sensitive to initiating seizure activity to varying degrees. Specificity was also observed between different injection sites within these structures in regard to seizure initiation. The results show a hierarchy of brain structures sensitive to initiating nerve agent‐induced seizures and within each structure a regional specificity that should be further examined as a target for anticonvulsant therapies.