Effect of stimulus intensity and number of treatments on ECS-related seizure duration and retrograde amnesia in rats.

Full Abstract

BACKGROUND: Animal models are frequently used to generate and test hypotheses about amnesia resulting from electroconvulsive therapy (ECT). Although many predictors of ECT-induced amnesia are known, their relative effects have been inadequately researched in the context of the animal models. OBJECTIVE: We sought to determine the relative retrograde amnestic effects of electroconvulsive shock (ECS) stimulus intensity (dose) and number on strong memories in rats. We also sought to identify dose-dependent ceiling amnestic effects, if any. METHODS: Adult rats (n = 144) were overtrained in a passive avoidance task using a step down apparatus. The rats were then randomized in a factorial design to receive one, two, or three once-daily bilateral ECS at 0-mC (sham ECS), 30-mC, 60-mC, 120-mC, or 180-mC doses. Recall of the pre-ECS training was assessed 1 day after the last ECS. RESULTS: Retrograde amnesia was observed only in rats that received 3 ECS; dose-dependent amnestic effects did not emerge. Higher stimulus intensity was associated with a small (13%) but significant increase in motor seizure duration, but only at the first ECS; stimulus intensity did not influence the attenuation of seizure duration across repeated occasions of ECS. CONCLUSION: With bilateral ECS, the number of ECSs administered is a more important variable than the ECS dose in weakening a strong, recently acquired, noxious memory; this finding may have important clinical implications. Higher stimulus intensity marginally increases motor seizure duration at the first ECS but does not influence the decrease in seizure duration across repeated ECSs.

Author information

Author/s: Andrade, Chittaranjan (C); Thyagarajan, S (S); Vinod, P S (PS); Srikanth, S N (SN); Rao, N S K (NS); Chandra, J Suresh (JS);

Affiliation: Department of Psychopharmacology, National Institute of Mental Health and Neurosciences, Bangalore, India. andrade(-atsign-)nimhans.kar

Journal and publication information

Publication Type: Journal Article

Journal: The journal of ECT (J ECT), published in United States. (Language: eng)

Reference: 2002-Dec; vol 18 (issue 4) : pp 197-202

Dates: Created 2002/12/06; Completed 2003/05/22; Revised 2004/11/17;

PMID: 12468995, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: 18 Feb 2009 00:00:00)

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