The ontogeny of seizures induced by leucine‐enkephalin and β‐endorphin

Abstract

Rats ranging in postnatal age from 6 hours to 28 days were implanted with cortical and depth electrodes as well as an indwelling cannula in the lateral ventricle. We then administered varying amounts of the opiate peptides leucine-enkephalin and β-endorphin intracerebroventricularly with continous electroencephalographic monitoring. Leucine-enkephalin produced electrical seizure activity in rats as young as 2 days. β-Endorphin administration was associated with seizures at the fifth postnatal day, with a high incidence of apnea resulting in death in animals as young as 6 hours. An adult seizure response to β-endorphin and leucine-enkephalin was seen at 15 and 28 days of age, respectively. Naloxone blocked the seizure produced by these opiate peptides in all age groups. The data indicate that the opiate peptides are potent epileptogenic compounds in developing brain, that seizures induced by leucine enkephalin differ from those caused by β-endorphin, and that petit mal–like seizure activity can be an adult response in the rodent.