Electroshock-induced retrograde amnesia and brain serotonin metabolism: Effects of several antidepressant compounds

Summary Mice treated with either amitriptyline, nialamide, or pipradol showed a significant degree of antagonism toward the amnesic effect of electroconvulsive shock administered 10 sec following a single conditioning trial. Saline-treated control animals showed a high incidence of amnesia for the same response as a result of post-training electroshock. Under control conditions, where no posttraining ECS was given, a consistently high level of conditioned response retention was shown. Although the mechanism of action for each of the drugs with regard to serotonin metabolism was quite different, a common factor in each case was that brain serotonin levels were generally reduced following ECS, whereas for control animals one post-ECS effect was elevated brain serotonin. The present findings suggest that elevation of brain serotonin levels produced by ECS, and taking place during the post-training interval within which the memory trace is consolidated, may account, in part, for the resulting retrograde amnesia; antagonism of the amnesic effect of ECS is apparently accomplished by providing for conditions wherein this ECS-induced serotonin change is blocked.This study was supported, in part, by Grants MH 08698-03 and MH 13191-01 from the U.S.P.H.S. The author wishes to acknowledge the technical assistance of M. Steinberg and M. Golod.