dermorphin and Epilepsy

Free-moving rats received intraventricular (i.c.v.) or intravenous (i.v.) injections of the mu opioid agonist dermorphin (DRM). The EEG activity of the cortex and of several structures near the injected lateral ventricle was recorded. The intravenous injections of DRM did not induce epileptiform activity. The intracerebroventricular injections of DRM triggered several types of electrical seizures and interictal spikes. With the aim of determining which structure gave rise to the epileptiform discharges, we compared the time relationships of epileptiform phenomena occurring in different structures. Epileptiform discharges, at once generalized, appeared first in the CA3 area of the ventral hippocampus, with involvement of the CA1 area of ventral hippocampus, the entorhinal cortex and the amygdala following immediately. We conclude that, after intracerebroventricular injection of a mu opiate agonist, epileptiform activity originates in the CA3 area of the ventral hippocampus.

Topics: Analgesics, Opioid; Animals; Brain; Electrodes, Implanted; Electroencephalography; Epilepsy; Hippocampus; Injections, Intravenous; Injections, Intraventricular; Oligopeptides; Opioid Peptides; Rats; Rats, Sprague-Dawley

To test the different sensitivity of several central structures to the epileptogenic action of mu opiate agonists, intracerebral microinjections of the selective mu agonist dermorphin were delivered into different areas of the rat dorsal and ventral hippocampus, septum, amygdala, entorhinal cortex, thalamus, striatum and neocortex. The dose of dermorphin (up to 6 nmol) necessary to trigger electrical epileptic events in each of these regions was studied. Epileptic discharges were triggered only in the ventral hippocampus (CA1 and CA3 areas), amygdala and entorhinal cortex. The epileptic induction threshold was the lowest in the CA1 area of the ventral hippocampus. The results suggest that when a mu opiate agonist is injected intraventricularly, the epileptic activity originates in the ventral hippocampus.

Topics: Animals; Dose-Response Relationship, Drug; Epilepsy; Injections, Intraventricular; Microinjections; Oligopeptides; Opioid Peptides; Rats; Rats, Sprague-Dawley; Receptors, Opioid, mu

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.

Topics: Animals; Cerebral Cortex; Cerebral Ventricles; Electroencephalography; Electromyography; Epilepsy; In Vitro Techniques; Injections, Intraventricular; Oligopeptides; Opioid Peptides; Rats; Rats, Inbred Strains

The effects of bombesin, sauvagine, physalaemin and dermorphin on rat CNS were observed. These peptides were administered to non-epileptic and epileptic rats: SEEG and DEEG were recorded. On the normal electrical background activity of rat brain only physalaemin had no effect. All the other peptides gave rise to slow activity with different duration. In the epileptic rat only sauvagine showed no effect whilst physalaemin reduced the epileptic activity, bombesin seemed to strengthen the action of metrazol and dermorphin blocked it at the onset. These observations will undergo FFT (Fast Fourier Transform) analysis.

Topics: Amphibian Proteins; Analgesics, Opioid; Animals; Bombesin; Brain; Electroencephalography; Epilepsy; Oligopeptides; Opioid Peptides; Peptide Hormones; Peptides; Physalaemin; Rats; Rats, Inbred Strains; Tachykinins; Vasodilator Agents