EFFECT OF ELECTROCONVULSIVE SHOCK-TREATMENT ON THE OPIOID-MEDIATED INHIBITION OF SEROTONIN RELEASE IN RAT HIPPOCAMPAL SLICES

WE investigated the influence of electroconvulsive shock treatment on the opioid-mediated inhibition of serotonin (5-HT) release. The overfl ow of [H-3]serotonin elicited by high potassium (30 mM) in superfused slices of rat hippocampus was significantly inhibited in the presence of two agonists, mu-selective [D-Ala2,N-methyl-Phe4,Gly5ol]enkephalin (DAGO) and delta-selective [D-Pen2,D-Pen5]enkephalin (DPDPE) in contro l animals. The repeated (once daily for 7 days) electroconvulsive shoc k treatment significantly reversed the inhibitory effect of both DAGO and DPDPE. Single electroconvulsive shock (1 day) had no effect on DAG O inhibition, on the contrary a trend to antagonism of the DPDPE effec t was reported. These results suggested that the opioids are associate d with the experimental induced seizures and that the ECS treatment mi ght regulate the serotonin release throughout the opioid receptor syst em.