Electroencephalographic and autonomic effects of centrally administered dermorphin in rabbits

Dermorphin, administered into the third ventricle of conscious rabbits, induces an increase of the total power density spectrum of the cortex and a decrease of the total power of the hippocampus. The electrocortical pattern is similar to that found with other opiates and reported as specific of mu agonists. Simultaneously the peptide causes respiratory depression, bradycardia and hypothermia. Naloxone (0.5 mg/kg IV) quickly and completely inverts all these effects. The activity of serotoninergic, Gabaergic, catecholaminergic and cholinergic systems does not seem to be required for these dermorphin actions. Thus, the hypothesis that dermorphin acts directly in modifying cerebral electrical activity is put forward.