title: 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 beta-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.
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado Denver, Denver, Colorado, USA.
authors.forename: Stuart G
authors.initials: SG
authors.lastname: Jarrett
authors.forename: Julie B
authors.initials: JB
authors.lastname: Milder
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Liang
authors.forename: Manisha
authors.initials: M
authors.lastname: Patel
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism; D005526:Food, Formulated; D005978:Glutathione / Q000378:metabolism*; D007657:Ketone Bodies / Q000008:administration & dosage*; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000975:Antioxidants; D001786:Blood Glucose; D007657:Ketone Bodies; D017382:Reactive Oxygen Species; D005978:Glutathione