APP and Alzheimer disease: Furthermore, in streptozocin (STZ i.c.v) -induced AD rats (77) and APP/PS1 mice (78), DPP-4 inhibitors sitagliptin and saxagliptin were observed to have the ability to eliminate Aβ accumulation, clear abnormal phosphorylation of tau, and improve brain mitochondrial dysfunction probably through activation of AMPK in neuronal cells (66).