INS and Alzheimer disease: The protein expression levels of the insulin signaling pathway including IRS1, Akt, and ERK and AD-related biomarkers including APP, p-Tau, and TREM1/2 in the hippocampus and PFC were detected via Western blot, and the mRNA expression levels of IL-1β, IL-6, TNF-α, ocln, zo-1, and clnds were measured by qPCR technique.