Working memory deficits induced by intrahippocampal administration of 8-OH-DPAT, a 5-HT1A receptor agonist, in the rat.

In a test of working memory using a three-panel runway task, the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), at 1.0 mg/kg i.p. significantly increased the number of errors (attempts to pass through two incorrect panels of the three panel gates at four choice points), but it had no effect on errors in a test of reference memory. Intrahippocampal injection of 8-OH-DPAT at 10 micrograms/side also significantly increased the number of working memory errors, without affecting that of reference memory errors. The effect of intrahippocampal 8-OH-DPAT (10 micrograms/side) on working memory was blocked by the 5-HT1A receptor antagonist, (-)-propranolol, at 5 mg/kg i.p. These results suggest that activation of hippocampal 5-HT1A receptors impairs working memory, but does not affect retention of reference memory.