Intracerebroventricular dermorphin, but not dermenkephalin, is epileptogenic in the rat

The effects of intracerebroventricular administration of dermorphin (mu agonist) and dermenkephalin (delta agonist) were studied at the electrocorticographic (ECoG) and electromyographic (EMG) levels in free-moving rats. A very low dose of dermorphin (125 pmol) induced ECoG spiking, occasional myoclonic jerks, wet-dog shakes and catalepsy. In addition, electrical seizures were triggered with doses of 250 to 500 pmol. These signs were reversed by an i.p. injection of naloxone (1 mg kg-1). However, no epileptic-like phenomena were seen after administration of dermenkephalin up to 1 nmol. These results indicate that mu but not delta receptors are involved in the epileptogenic effect of intraventricularly administered opiates.