Long-term enhancement of entorhinal-dentate evoked potentials following 'modified' ECS in the rat.
Electroconvulsive therapy (ECT) is widely used as a treatment for drug-resistant depression. The animal analogue of ECT is electroconvulsive shock (ECS) seizures. We have recently shown that repeated ECS seizures cause a long-lasting, perhaps permanent, enhancement in entorhinal-dentate evoked potentials in the rat. Our study, however, involved 'unmodified' ECS, whereas in clinical practice ECT is now usually given in its 'modified' form (with near-threshold currents, a short-acting barbiturate, muscle relaxant and oxygen). We have therefore repeated our experiments using modified ECS. Entorhinal-dentate evoked potentials were measured in Long-Evans rats before and after: (1) eight modified ECS seizures; or (2) eight sham modified ECS trials. Despite the use of the modified procedure, a significant and long-lasting enhancement in population spike amplitude was seen in the ECS group. We conclude that the modified procedure does not protect rats against the long-lasting enhancement of evoked potentials. Similar changes may be occurring in the brains of patients subjected to modified ECT.
Gombos
Z
Z
Bloorview Epilepsy Program, University of Toronto, ON, Canada.
Mendonça
A
A
Racine
R J
RJ
Cottrell
G A
GA
Burnham
W M
WM
D000818:Animals; D018891:Dentate Gyrus / Q000166:cytology / Q000502:physiology*; D004565:Electroconvulsive Therapy; D018728:Entorhinal Cortex / Q000166:cytology / Q000502:physiology*; D005071:Evoked Potentials / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012640:Seizures / Q000209:etiology / Q000503:physiopathology; D013997:Time Factors