INSR and Alzheimer disease: Radix Rehmanniae Praeparata (Shu Dihuang, SD) is widely used as primal medicine in Chinese herbal formulas for the treatment of AD and exerts neuroprotective effects on ICV-STZ-induced AD mice through modulation of INSR/IRS-1/AKT/GSK-3β signaling pathway and intestinal microbiota [8].