Hippocampal alpha7 nicotinic receptors modulate memory reconsolidation of an inhibitory avoidance task in mice

BOCCIA, MM; BLAKE, MG; KRAWCZYK, MC; BARATTI, CM

NEUROSCIENCE

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2010

0306-4522

CF-1 male mice were trained in an inhibitory avoidance task using either a mild or a high footshock (0.8 or 1.2 mA, 50 Hz, 1s). A retention test was given 48 hours later. Immediately after the retention test, mice were given intra-dorsal hippocampus infusions of either choline (Ch, an α7 nicotinic acetylcholine receptor agonist, 0.08 – 1.30 mg/hippocampus), or methyllycaconitine (MLA, an α7 nicotinic acetylcholine receptor antagonist, 1.0 – 30.0 mg/hippocampus). Memory retention was tested again 24 h later. Methyllycaconitine impaired retention performance regardless of footshock intensity and its effects were long lasting. Ch impaired retention performance only in those mice trained with a high footshock. On the contrary, Ch enhanced retention performance when mice were trained with a mild footshock. These effects were long lasting and dose- and time-dependent. Retention performance was not affected in drug-treated mice that were not subjected to memory reactivation, suggesting that the performance effects could not be attributable to non-specific effects of the drugs. Methyllycaconitine effects were dose-dependently reversed by choline, suggesting that MLA and Ch interact at the a7nAChR. Altogether, results suggest that hippocampal a7nAChRs play a critical role in reconsolidation of an inhibitory avoidance response in mice, and may also have important implications for dynamic memory processes. This is the first presentation, to our knowledge, indicating that a specific receptor (a7nAChR) is able to modulate consolidated memories after retrieval.