The ketogenic diet increases mitochondrial glutathione levels

Abstract

The ketogenic diet (KD) is a high‐fat, low carbohydrate diet that is used as a therapy for intractable epilepsy. However, the mechanism(s) by which the KD achieves neuroprotection and/or seizure control are not yet known. We sought to determine whether the KD improves mitochondrial redox status. Adolescent Sprague–Dawley rats (P28) were fed a KD or control diet for 3 weeks and ketosis was confirmed by plasma levels of β‐hydroxybutyrate (BHB). KD‐fed rats showed a twofold increase in hippocampal mitochondrial GSH and GSH/GSSG ratios compared with control diet‐fed rats. To determine whether elevated mitochondrial GSH was associated with increased de novo synthesis, the enzymatic activity of glutamate cysteine ligase (GCL) (the rate‐limiting enzyme in GSH biosynthesis) and protein levels of the catalytic (GCLC) and modulatory (GCLM) subunits of GCL were analyzed. Increased GCL activity was observed in KD‐fed rats, as well as up‐regulated protein levels of GCL subunits. Reduced CoA (CoASH), an indicator of mitochondrial redox status, and lipoic acid, a thiol antioxidant, were also significantly increased in the hippocampus of KD‐fed rats compared with controls. As GSH is a major mitochondrial antioxidant that protects mitochondrial DNA (mtDNA) against oxidative damage, we measured mitochondrial H2O2 production and H2O2‐induced mtDNA damage. Isolated hippocampal mitochondria from KD‐fed rats showed functional consequences consistent with the improvement of mitochondrial redox status i.e. decreased H2O2 production and mtDNA damage. Together, the results demonstrate that the KD up‐regulates GSH biosynthesis, enhances mitochondrial antioxidant status, and protects mtDNA from oxidant‐induced damage.

Lethal mitochondrial cardiomyopathy in a hypomorphic Med30 mouse mutant is ameliorated by ketogenic diet

“…4A). These data are consistent with reports that a KD induces up-regulation of Ppargc1a expression (26) and reduces oxidative stress (27). We infer that the KD counterbalances the detrimental effects of the zeitgeist mutation by stimulating, through unknown mechanisms, the expression of Ppargc1a, Esrra, and other OXPHOS genes.…”

Ketogenic diets, mitochondria, and neurological diseases

“…The increase in GSH and levels of the GCL subunits, GCL catalytic subunit and GCL modulatory subunit, observed by Jarrett et al ( 96 ) prompted an investigation to examine the role of nuclear factor erythroid 2-related factor 2 (Nrf2), as activation of this redox-sensitive transcription factor is the primary mechanism that induces this antioxidant pathway ( 97 ). Nrf2 is activated by cellular stress and initiates transcription of a diverse set of genes, such as antioxidant defense, drug transporters, metabolic enzymes, and transcription factors, by binding to the antioxidant or electrophile response elements ( 98 ).…”

“…A decrease in substrate-driven mitochondrial H 2 O 2 production was shown in rats after 3 weeks on the diet, and this was associated with increased mitochondrial GSH levels, depletion of which is known to occur with seizures ( 96 ). The increase in GSH was associated with elevated activity of the rate-limiting enzyme in GSH biosynthesis, glutamate cysteine ligase (GCL), and enhanced expression of the GCL catalytic subunit and the GCL modulatory subunit in rats fed the KD ( 96 ).…”

Novel Mitochondrial Targets for Neuroprotection

“…Increasing mitochondrial antioxidant activities by elevating mitochondrial reducing power is considered as an important mechanism of neuroprotection by several naturally occurring compounds, including ketone bodies, pyruvate, and acyl-carnitines (Ryu et al, 2004;Zanelli et al, 2005;Gasior et al, 2006;Zhao et al, 2006b;Jarrett et al, 2008;Rosca et al, 2009;Alves et al, 2009;Jones et al, 2010;Zhang et al, 2010). This mechanism of action might be particularly important during reperfusion after cerebral ischemia, when the mitochondrial redox state is hyperoxidized, ROS production is elevated, and there are increased markers of oxidative molecular modification (Perez-Pinzon et al, 1999;Fiskum et al, 2004).…”