Enhancing brain mitochondrial respiration could conceivably benefit diseases with reduced brain electron transport chain enzyme activities. This includes several common diseases such as Alzheimer's disease and Parkinson's disease. We and others have proposed that shifting cell cytosolic redox balances towards a more oxidized state might increase mitochondrial respiration and that this may have therapeutic consequences. To accomplish this manipulation my laboratory has screened a number of compounds, and preliminary experiments suggest oxaloacetate (OAA), whose reduction to malate is coupled to the oxidation of NADH to NAD+, holds particular promise. OAA, a dicarboxylic acid, is a Krebs cycle and gluconeogenesis intermediate. You can purchase it as a nutritional supplement. One manufacturer markets it as a caloric restriction mimetic and "longevity supplement". These claims are based on a 2009 study in which OAA-treated C. elegans worms outlived untreated worms. Two in vivo OAA vertebrate studies are also reported. The first is a 1968 study of human diabetics, which found that OAA treatment lowered blood glucose levels. The second is a 2003 study performed on mice, which found OAA prevented kainic acid-induced seizures, brain mtDNA degradation, and lipid peroxidation. Aside from these three studies OAA supplementation effects are essentially unknown. In preliminary studies we found adding OAA to neuroblastoma cells robustly increased mitochondrial oxygen consumption. In mice, we found systemically administered OAA increased brain PGC1a levels. Brain TNFa expression, on the other hand, was reduced and ERK1/2 phosphorylation trended in the same direction. Based on conceptual and preliminary data considerations OAA therefore warrants further consideration as a pro-respiration, pro-mitochondrial biogenesis agent that may act as a brain-penetrating caloric restriction mimetic. I am therefore hypothesizing systemically administered OAA will activate pathways that contribute to or mediate brain mitochondrial biogenesis. Support for this hypothesis would justify additional, more detailed studies of how OAA supplements affect brain metabolism, signaling pathways, and gene expression. The pilot studies we now propose will further test how systemically administered OAA affects brain mitochondrial biogenesis, proteins and pathways that are implicated in mitochondrial biogenesis, and nutrient sensing pathways in OAA-treated mice.
In Aim 1 we will characterize brain bioenergetics and bioenergetics-related pathways in young OAA-treated mice.
In Aim 2 we will characterize brain bioenergetics and bioenergetics-related pathways in aged mice treated with OAA over a 12-month period. If the studies I now propose confirm and extend our preliminary findings, the case for developing OAA or OAA-like drugs for the treatment of diseases with reduced brain bioenergetics will be immensely strengthened.
We will test the ability of oxaloacetic acid (OAA) to activate brain mitochondrial biogenesis, proteins and pathways implicated in mitochondrial biogenesis, and nutrient sensing pathways in mice. Our hypothesis is that systemically administered OAA will activate pathways that contribute to or mediate brain mitochondrial biogenesis. Our preliminary data show OAA functions as a pro-respiration, pro-mitochondrial biogenesis agent that acts as a brain-penetrating caloric restriction mimetic;confirming and extending our preliminary data would support the case for developing OAA or OAA-like drugs for the treatment of diseases with reduced brain bioenergetic capacity.
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