Changes in hippocampal immunoreactive dynorphin and neoendorphin content following intra-amygdalar kainic acid-induced seizures

Kainic acid (KA) injected focally into the amygdala induced spontaneous recurrent motor seizures. One to 6 hr after the injection of KA, the hippocampal ir-dynorphin (ir-DYN) was significantly lowered whereas 24 hr after the injection it increased. The hippocampal level of ir-alpha-neoendorphin decreased 6 hr after KA injection, and reached the control level 24 hr after the injection. Chlordiazepoxide (5 mg/kg) and phenobarbital (40 mg/kg) blocked convulsions as well as the increase in the ir-DYN content. Cycloheximide (500 micrograms icv) also antagonized the increase in the hippocampal ir-DYN. The above findings suggest that hippocampal dynorphin-related peptides are released during the seizures and that these peptides may play a physiological role in the seizure phenomena and limbic excitability.