Naloxone-induced seizures in rats infected with Borna disease virus.

The opioid antagonist naloxone is widely used in the emergency treatment of nontraumatic coma. Although it is uncommon for serious side effects to result from administration of opiate antagonists, we report that naloxone can have epileptogenic effects in the context of encephalitis. In an experimental model of viral encephalitis, rats infected with Borna disease virus developed myoclonic, generalized clonic, or atonic seizures; behavior arrest; and staring spells when treated with naloxone. These findings suggest a novel neuropharmacologic link, through opioid peptide systems, between epilepsy and encephalitis and disclose a potential contraindication to use of opioid antagonists in nontraumatic coma.