HTR2A and memory impairment: In the present study, it is still uncertain whether PACAP-induced 5-HT2A internalization can be a mechanism for behavioral abnormalities including hyperactivity, PPI deficits, depressive-like behavior and memory impairment, reversal of the depressive-like behavior by the 5-HT2A antagonist ritanserin, and exaggerated DOI-induced hallucinogenic behaviors in Pacap–/– mice.