“…They include analysis of mitochondria-specific proteins, functional interrogation of isolated mitochondria or mitochondria in synaptosome preparations, and manipulation of genes that encode mitochondrial proteins (Grimm and Eckert, 2017). Comparisons of mitochondria isolated from brain tissue of animals reveal numerous age-related alterations, including mitochondrial enlargement or fragmentation (Stahon et al, 2016; Morozov et al, 2017), increased oxidative damage to mitochondrial DNA (Kim and Chan, 2001; Santos et al, 2013), impaired function of the electron transport chain (ETC) (Yao et al, 2010; Pandya et al, 2015, 2016; Pollard et al, 2016), increased numbers of mitochondria with depolarized membranes (Lores-Arnaiz et al, 2016), impaired Ca 2+ handling (Leslie et al, 1985; Pandya et al, 2015), and a reduced threshold for triggering mPTP formation (Brown et al, 2004). The decrement in mitochondrial function during brain aging involves a decline in cellular NAD + levels and the NAD:NADH ratio (Braidy et al, 2014), which would be expected to compromise the activities of NAD + -dependent enzymes critical for neuronal function and viability, including protein deacetylases of the sirtuin family (Fang et al, 2017).…”