Targeting Mitochondrial Dysfunction in Alzheimer's Disease Neurons: Lithium Boosts Oxidative Phosphorylation

Alzheimer's disease (AD) is characterized by the accumulation of amyloid beta (Aβ) and neurofibrillary tangles in brain tissue; however, AD is multifactorial, and different etiopathogenic mechanisms involve factors that can affect mitochondrial function, which are associated with AD. While high-dose lithium is a well-established mood stabilizer, accumulating evidence suggests that low-dose lithium provides significant neuroprotection by reversing AD pathology, cognitive impairment, and inflammation. Despite these findings, there is limited information on how lithium affects brain energy metabolism. In the current study, we investigated the effect of lithium (0, 0.1, 1, and 10 mM) on mitochondrial function in AD neurons. Neuronal cells were isolated from the hippocampi of embryonic day 14-17 (E15-E17) control (C57BL/6) mice and 3xTg-AD mice. Mitochondrial oxygen consumption rate (OCR), mitochondrial Cytochrome C Oxidase (COX) activity, total ATP activity, and the expression of mitochondrial complex protein involved in oxidative phosphorylation (OXPHOS) were measured in control vs. 3xTg-AD in the presence and absence of lithium treatment. In the present study, lithium treatment significantly increased (p < 0.05) mitochondrial OCR, COX, total ATP, and levels of mitochondrial complex protein subunits (Complex I-V) in 3xTg-AD neurons. However, lithium had no effect on energy metabolism in control neurons. Together, these data indicate that lithium improves mitochondrial function under pathological states. Overall, these results have important implications for the treatment of disorders in which brain energy regulation is compromised, including AD. Particularly, our results highlight a role for lithium in regulating bioenergetics in early-stage AD and suggest that neuronal cells may be a crucial therapeutic target for preventing AD.