PTGS2 and memory impairment: To explore whether PAF modulatory actions were involved in the pharmacological effect of YY-1224 against Aβ (1-42)-induced memory impairments, the expressions of PAFR and PAF-AH were examined in the hippocampus of COX-2 (+/+)- and COX-2 (−/−)-mice using immunocytochemistry and RT-rt-PCR.