Enhancement of the memory of a previously learned aversive habit following pre-test administration of a variety of serotonergic antagonists in mice.

The present study examined the effects of pre-test administration of a number of serotonergic receptor antagonists on the retrieval of a previously learned aversive habit in the mouse. All of the receptor antagonists (pirenperone, ketanserin, mianserin, methysergide and metergoline) produced a dose-dependent increase in the latency to complete 5 s of drinking 48 h after training. This suppression of drinking could not be attributed to nonspecific effects of the drugs on behavior (e.g., illness, reduced thirst, or activity), as non-contingently trained mice failed to exhibit similar elevations in their test scores. These results are, therefore, further support for an important role for serotonin in the processes underlying learning and memory.