Previous studies showed that the neuroprotective benefits of 17β-estradiol (E2) ameliorated cholinergic deficit, elevated the expression levels of choline acetyltransferase and 5-hydroxytryptamine receptor 2A, and lowered the expression of GFAP in a rat model of Alzheimer’s disease induced by OVX [77]. This evidence concerns the gene HTR2A and Alzheimer disease.