title: Ketosis may promote brain macroautophagy by activating Sirt1 and hypoxia-inducible factor-1.
abstract: Ketogenic diets are markedly neuroprotective, but the basis of this effect is still poorly understood. Recent studies demonstrate that ketone bodies increase neuronal levels of hypoxia-inducible factor-1α (HIF-1α), possibly owing to succinate-mediated inhibition of prolyl hydroxylase activity. Moreover, there is reason to suspect that ketones can activate Sirt1 in neurons, in part by increasing cytoplasmic and nuclear levels of Sirt1's obligate cofactor NAD(+). Another recent study has observed reduced activity of mTORC1 in the hippocampus of rats fed a ketogenic diet - an effect plausibly attributable to Sirt1 activation. Increased activities of HIF-1 and Sirt1, and a decrease in mTORC1 activity, could be expected to collaborate in the induction of neuronal macroautophagy. Considerable evidence points to moderate up-regulation of neuronal autophagy as a rational strategy for prevention of neurodegenerative disorders; elimination of damaged mitochondria that overproduce superoxide, as well as clearance of protein aggregates that mediate neurodegeneration, presumably contribute to this protection. Hence, autophagy may mediate some of the neuroprotective benefits of ketogenic diets. Brain-permeable agents which activate AMP-activated kinase, such as metformin and berberine, as well as the Sirt1 activator nicotinamide riboside, can also boost neuronal autophagy, and may have potential for amplifying the impact of ketogenesis on this process. Since it might not be practical for most people to adhere to ketogenic diets continuously, alternative strategies are needed to harness the brain-protective potential of ketone bodies. These may include ingestion of medium-chain triglycerides or coconut oil, intermittent ketogenic dieting, and possibly the use of supplements that promote hepatic ketogenesis - notably carnitine and hydroxycitrate - in conjunction with dietary regimens characterized by long daily episodes of fasting or carbohydrate avoidance.
authors: Catalytic Longevity, 7831 Rush Rose Dr., Apt. 316, Carlsbad, CA 92009, United States. Electronic address: markfmccarty@gmail.com.
authors: Mark F
authors: MF
authors: McCarty
authors: Preventive Cardiology Dept., St. Luke's Mid America Heart Institute, Kansas City, MO, United States.
authors: James J
authors: JJ
authors: DiNicolantonio
authors: Preventive Cardiology Dept., St. Luke's Mid America Heart Institute, Kansas City, MO, United States.
authors: James H
authors: JH
authors: O'Keefe
mesh_terms: D000107:Acetylation; D000818:Animals; D001343:Autophagy / Q000502:physiology*; D001921:Brain / Q000503:physiopathology*; D055423:Diet, Ketogenic; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology*; D007659:Ketones / Q000378:metabolism; D007662:Ketosis / Q000503:physiopathology*; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes / Q000378:metabolism; D018696:Neuroprotective Agents / Q000378:metabolism; D056564:Sirtuin 1 / Q000502:physiology*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007659:Ketones; D046912:Multiprotein Complexes; D018696:Neuroprotective Agents; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; C447939:SIRT1 protein, human; D056564:Sirtuin 1