PTGER1 and Alzheimer disease: Among the specific receptors for eicosanoids, the mRNA levels of PGE2 receptor 1 (EP1), PGD2 receptor 1 (DP1), PGI2 receptor (IP), and TXA2 receptor (TXA2r) were lower in the AD brains, while those of DP2 and IP were lower in the Cerad-b brains (Figures 4K–M).