Blockade of striatal 5-HT2 receptors produces retrograde amnesia in rats.

We have recently reported that intrastriatal administration of the serotonin (5-HT) releasing drug p-chloroamphetamine, and of 5-HT itself, produces a significant retention deficit of inhibitory avoidance. It is not known which of the 5-HT receptors are involved in the amnesic effect of serotonin. The present experiment was aimed at determining whether 5-HT2 receptors within the striatum are involved in memory consolidation. Ketanserine (0.5, 1.0, 2.0, or 4.0 ng) was infused bilaterally into the striatum of Wistar rats immediately after training of inhibitory avoidance, and retention of the task was measured 24 h later. A dose-dependent retention deficit was found. Together with the results from appropriate control groups, the results strongly suggest that striatal 5-HT2 receptors participate in memory consolidation of this aversive task.