Apamin improves learning in an object recognition task in rats.

Object recognition was investigated in rats in a two trial unrewarded task. In the first trial, two copies of the same object were presented. In the second trial, one of the familiar object and a new object were presented. Rats explored the new object longer than the familiar object when the intertrial time was 1 h, indicating that they remembered the familiar object, but not when the intertrial time was 24 h. Rats injected with apamin (a toxin which blocks specifically Ca(2+)-activated K(+)-channels) before the first trial spent more time in exploring the new object than the familiar object at the second trial, when it took place 24 h after the first trial. Injection of apamin just after the first trial or before the second trial did not modify the difference in exploration time between the new and the familiar object. These results suggest that the blockade of Ca(2+)-activated K(+)-channels could improve learning, but not consolidation nor restitution of the information, in an object recognition task.