Memory consolidation and reconsolidation of an inhibitory avoidance response in mice: effects of i.c.v. injections of hemicholinium-3

• Published in: Neuroscience 2004, Vol.124 (4), p.735-741
• Main Authors: Boccia, M.M, Acosta, G.B, Blake, M.G, Baratti, C.M
• Format: Article
• Language: English
• Subjects: acetylcholine; Animals; Avoidance Learning - drug effects; Binding, Competitive; Biological and medical sciences; Choline - antagonists & inhibitors; Choline - metabolism; Cholinergic Agents - administration & dosage; consolidation; Fundamental and applied biological sciences. Psychology; Hemicholinium 3 - administration & dosage; hemicholinium-3; Hippocampus - metabolism; Injections, Intraventricular; Male; memory; Memory - drug effects; Mice; Mice, Inbred Strains; reconsolidation; Retention (Psychology) - drug effects; Vertebrates: nervous system and sense organs
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2004.01.001

The immediate post-training i.c.v. administration of hemicholinium-3 (HC-3) (1 μg), 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 μl) 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 μg) 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.