Behavioral effects of apamin, a selective inhibitor of the SKCa-channel, in mice and rats

Apamin, a highly selective and potent peptide that blocks the SKCa-channels has been suggested to be a cognition enhancer. We tested apamin in the Mor ris water escape task, in shock motivated avoidance tasks, and in operant t asks in the Skinnerbox. We also used noncognitive tests, such as the rat fo rced swimming test and cocaine-induced locomotor activity in the open field , and a test to assess the side effect profile. Mice and rats from differen t strains, and rats of different ages were used. The rat studies provided o nly weak support for the notion that apamin acts as a cognition enhancer. M ore convincing evidence was obtained from the mouse studies. Overt side eff ects of apamin were found at the dose of 0.3 mg kg(-1). This dose was close to, or even overlapped, the doses which improved cognition in mice. We con clude that apamin is a poor tool to assess the role of SKCa-channels in lea rning and memory processes. (C) 1999 Elsevier Science Ltd. All rights reser ved.