Anterograde effects of a single electroconvulsive shock on inhibitory avoidance and on cued fear conditioning.
A single electroconvulsive shock (ECS) or a sham ECS was administered to male 3-4-month-old Wistar rats 1, 2, and 4 h before training in an inhibitory avoidance test and in cued classical fear conditioning (measured by means of freezing time in a new environment). ECS impaired inhibitory avoidance at all times and, at 1 or 2 h before training, reduced freezing time before and after re-presentation of the ECS. These results are interpreted as a transient conditioned stimulus (CS)-induced anxiolytic or analgesic effect lasting about 2 h after a single treatment, in addition to the known amnesic effect of the stimulus. This suggests that the effect of anterograde learning impairment is demonstrated unequivocally only when the analgesic/anxiolytic effect is over (about 4 h after ECS administration) and that this impairment of learning is selective, affecting inhibitory avoidance but not classical fear conditioning to a discrete stimulus.
Departamento de Psicobiologia, Universidade Federal de São Paulo, Escola Paulista de Medicina, Brasil. mgabi@psicobio.epm.br
M G
MG
Oliveira
O F
OF
Bueno
E B
EB
Gugliano
D000647:Amnesia / Q000503:physiopathology; D000698:Analgesia; D000818:Animals; D001007:Anxiety / Q000503:physiopathology; D001362:Avoidance Learning / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D004597:Electroshock / Q000379:methods*; D005239:Fear / Q000502:physiology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors