Intrahippocampal injections of a specific mu-receptor ligand PL017 produce generalized convulsions in rats.

The effects of a selective mu-agonist, [NMe-Phe3-D-Pro4]morphiceptin (PL017), and a selective mu-antagonist, beta-funaltrexamine (beta-FNA), on convulsions and wet dog shakes (WDS) were studied. Electroencephalogram demonstrated that a single injection of PL017 into the ventral hippocampus evoked epileptiform spiking which appeared initially in the ventral hippocampus and spread to the cortical area when the animal developed generalized convulsion. Behavioral studies showed that PL017-induced convulsions and WDS were dose-dependent, and these behavioral changes were blocked by beta-FNA pretreatment. The results indicate that mu-receptors in the hippocampus may play an important role in seizure activities evoked by opioids.