Memory consolidation and reconsolidation of an inhibitory avoidance response in mice: effects of i.c.v. injections of hemicholinium-3.
The immediate post-training i.c.v. administration of hemicholinium-3 (HC-3) (1 microg), a specific inhibitor of the high-affinity choline uptake (HACU) in brain cholinergic neurons, impaired retention test performance of a one-trial step-through inhibitory avoidance response in adult male CF-1 mice. The effect was observed in mice that received a footshock (0.8 mA, 50 Hz, 1 s) on the learning trial, and not only 48 h after training, but also 7 days after it. After the completion of the retention test at each of the training-test interval that were studied, the HACU in the hippocampus of HC-3-treated mice was not significantly different from that of saline-injected (1 microl) control groups. Mice that were over-reinforced (1.2 mA, 50 Hz, 1 s) on the learning trial, exhibited a high retention performance 48 h after training. The immediate i.c.v. injection of HC-3 (1 microg) after the retention test, that is, after memory reactivation, significantly impaired retention performance over 4 consecutive days, whereas the saline-injected control group shown a slight, but significant performance decrease only at the last retention test. Retention performance was unchanged in HC-3-treated mice not undergoing memory reactivation session. These results, taken together, indicate that HC-3, not only impaired consolidation, but also reconsolidation of an inhibitory avoidance task in mice, suggesting a critical participation of central cholinergic mechanisms in both memory processes.
Boccia
M M
MM
Laboratorio de Neurofarmacología de Procesos de la Memoria, Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
Acosta
G B
GB
Blake
M G
MG
Baratti
C M
CM
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001667:Binding, Competitive; D002794:Choline / Q000037:antagonists & inhibitors / Q000378:metabolism; D018678:Cholinergic Agents / Q000008:administration & dosage*; D006426:Hemicholinium 3 / Q000008:administration & dosage*; D006624:Hippocampus / Q000378:metabolism; D007276:Injections, Intraventricular; D008297:Male; D008568:Memory / Q000187:drug effects*; D051379:Mice; D008815:Mice, Inbred Strains; D012153:Retention, Psychology / Q000187:drug effects
D018678:Cholinergic Agents; D006426:Hemicholinium 3; D002794:Choline