Apamin improves reference memory but not procedural memory in rats by blocking small conductance Ca2+-activated K+ channels in an olfactory discrimination task

Apamin blocks SK channels responsible for long-lasting hyperpolarization fo llowing the action potential. Using an olfactory associative task, the effe ct of an intracerebroventricular 0.3 ng apamin injection was tested on lear ning and memory. Apamin did not modify the learning of the procedure side o f the task or the learning of the odor-reward association. To test referenc e memory specifically. the rats were trained on a new odor-association prob lem using the same procedure (acquisition session), and they were tested fo r retention 24 h later. Apamin injected before or after the acquisition ses sion improved retention of the valence of a new odor pair. Apamin injected before the retention session did not affect the retrieval of the new valenc e. Thus, the results indicate that the blockage of apamin-sensitive SK chan nels facilitate consolidation on new-odor-reward association. (C) 2001 Else vier Science B.V. All rights reserved.