It was illustrated that intraperitoneal administration of the tetrapeptide SS-31 to Tg2576 mice (AD model) in the cerebral cortex reduces the level of the Aβ peptide and increases the level of mRNA and the synthesis of mitochondrial dynamic proteins (Mfn1/Mfn2), mitochondrial biogenesis (PGC1-α and Nrf2), and synaptic functions (synaptophysin and PSD95) [51]. Here, MFN1 is linked to Alzheimer disease.