Garbow JR, Doherty JM, Schugar RC, Travers S, Weber ML, Wentz AE, Ezenwajiaku N, Cotter DG, Brunt EM, Crawford PA. Hepatic steatosis, inflammation, and ER stress in mice maintained long term on a very low-carbohydrate ketogenic diet. Am J Physiol Gastrointest Liver Physiol 300: G956 -G967, 2011. First published March 31, 2011 doi:10.1152/ajpgi.00539.2010.-Low-carbohydrate diets are used to manage obesity, seizure disorders, and malignancies of the central nervous system. These diets create a distinctive, but incompletely defined, cellular, molecular, and integrated metabolic state. Here, we determine the systemic and hepatic effects of longterm administration of a very low-carbohydrate, low-protein, and high-fat ketogenic diet, serially comparing these effects to a highsimple-carbohydrate, high-fat Western diet and a low-fat, polysaccharide-rich control chow diet in C57BL/6J mice. Longitudinal measurement of body composition, serum metabolites, and intrahepatic fat content, using in vivo magnetic resonance spectroscopy, reveals that mice fed the ketogenic diet over 12 wk remain lean, euglycemic, and hypoinsulinemic but accumulate hepatic lipid in a temporal pattern very distinct from animals fed the Western diet. Ketogenic diet-fed mice ultimately develop systemic glucose intolerance, hepatic endoplasmic reticulum stress, steatosis, cellular injury, and macrophage accumulation, but surprisingly insulin-induced hepatic Akt phosphorylation and whole-body insulin responsiveness are not impaired. Moreover, whereas hepatic Pparg mRNA abundance is augmented by both high-fat diets, each diet confers splice variant specificity. The distinctive nutrient milieu created by long-term administration of this low-carbohydrate, low-protein ketogenic diet in mice evokes unique signatures of nonalcoholic fatty liver disease and whole-body glucose homeostasis. nutrient state; magnetic resonance spectroscopy; peroxisome proliferator activated receptor-␥; insulin resistance; unfolded protein response; x-box-binding protein-1 splicing; high-fat diets; fatty liver disease THERAPEUTIC USE OF REDUCED-CARBOHYDRATE diets has been extensively studied for the amelioration of a multitude of clinical states, including obesity and its metabolic complications, seizure disorders, and malignancies of the central nervous system (21,23,26,36,41,54,55,59,64). Nonetheless, the full scope of metabolic effects incurred by low-, and very low (ketogenic)-carbohydrate diets (KD) has only been preliminarily characterized. In wild-type mice, KDs result in weight loss and increased hepatic and myocardial fatty acid oxidation, compared with mice maintained on standard chow diets rich in polysaccharides (5,35,62). Whereas leptin-deficient obese (ob/ob) animals maintained on KD for 7 wk exhibit persistent weight gain, glucose tolerance and insulin resistance improve compared with ob/ob mice maintained on standard chow diet (3, 57). Collectively, encouraging preclinical and clinical studies of low-carbohydrate KDs have favored their continued study for anticonv...

The neuronal ceroid lipofuscinoses (Batten disease) are a group of inherited neurodegenerative diseases characterized by the progressive intralysosomal accumulation of autofluorescent material in many cells, visual defects, seizures, cognitive deficits, and premature death. Infantile neuronal ceroid lipofuscinosis (INCL) has the earliest onset ( approximately 1.5 years of age) and is caused by a deficiency in the lysosomal enzyme palmitoyl protein thioesterase-1 (PPT1). Currently there is no effective treatment for children with INCL. In this study, newborn PPT1-deficient mice received two (cortex), four (cortex and hippocampus), or six (cortex, hippocampus, and cerebellum) bilateral intracranial injections of AAV2-PPT1. The AAV-treated animals had localized increases in PPT1 activity, decreased autofluorescent material, improved histologic parameters, and increased brain mass. In addition, the treated animals had dose-dependent improvements in a battery of behavioral tests and improved interictal electroencephalographic tracings. However, there was neither a significant decrease in seizure frequency nor an increase in longevity even in INCL animals receiving six injections. These data suggest that early treatment of INCL using gene transfer techniques can be efficacious. However, higher levels or a broader distribution of PPT1 expression, or both, will be required for more complete correction of this neurodegenerative disease.

Heart muscle is metabolically versatile, converting energy stored in fatty acids, glucose, lactate, amino acids, and ketone bodies. Here, we use mouse models in ketotic nutritional states (24 h of fasting and a very low carbohydrate ketogenic diet) to demonstrate that heart muscle engages a metabolic response that limits ketone body utilization. Pathway reconstruction from microarray data sets, gene expression analysis, protein immunoblotting, and immunohistochemical analysis of myocardial tissue from nutritionally modified mouse models reveal that ketotic states promote transcriptional suppression of the key ketolytic enzyme, succinyl-CoA:3-oxoacid CoA transferase (SCOT; encoded by Oxct1), as well as peroxisome proliferatoractivated receptor ␣-dependent induction of the key ketogenic enzyme HMGCS2. Consistent with reduction of SCOT, NMR profiling demonstrates that maintenance on a ketogenic diet causes a 25% reduction of myocardial 13 C enrichment of glutamate when 13 C-labeled ketone bodies are delivered in vivo or ex vivo, indicating reduced procession of ketones through oxidative metabolism. Accordingly, unmetabolized substrate concentrations are higher within the hearts of ketogenic diet-fed mice challenged with ketones compared with those of chow-fed controls. Furthermore, reduced ketone body oxidation correlates with failure of ketone bodies to inhibit fatty acid oxidation. These results indicate that ketotic nutrient environments engage mechanisms that curtail ketolytic capacity, controlling the utilization of ketone bodies in ketotic states.The mammalian heart must maintain constant levels of ATP to perform its mechanical and electrical functions. A variety of experimental approaches have established that cardiomyopathy is associated with changes in cardiac energy metabolism and that altered energy metabolism can cause cardiomyopathy (1-5). In the normal adult heart, mitochondrial oxidative phosphorylation provides more than 95% of the ATP generated. Substrate utilization is dynamic, and metabolic flexibility under differing physiological conditions is an important adaptive property of myocardium (6 -8). Adaptations over time are

To compensate for the energetic deficit elicited by reduced carbohydrate intake, mammals convert energy stored in ketone bodies to high energy phosphates. Ketone bodies provide fuel particularly to brain, heart, and skeletal muscle in states that include starvation, adherence to low carbohydrate diets, and the neonatal period. Here, we use novel Oxct1 ؊/؊ mice, which lack the ketolytic enzyme succinyl- Transition from the intrauterine to the extrauterine environment incurs a marked shift in nutrient delivery and energy metabolism. A continuous pipeline replete with glucose and lactate, but calorically reduced in lipid, is replaced by a reduced carbohydrate, high fat milk diet that is cyclically interrupted by periods of nutrient deprivation (1-3). High energy-requiring organs like heart and skeletal muscle are poised to meet the energetic demands of this new nutrient environment because they are endowed with enzymatic machinery that avidly generates high energy phosphates from oxidative metabolism of fatty acids and lactate (4). Unlike cardiomyocytes and skeletal myocytes, most neurons oxidize fatty acids poorly and therefore remain dependent on hepatic gluconeogenesis to support energetic needs (5-8). However, because newborn brain comprises 10% of body weight and requires up to 60% of total body energy expenditure, maintenance of energetic homeostasis in the nervous system requires allocation of multiple fuels for metabolic homeostasis in the neonatal period. The rate of ketone body extraction by human neonatal brain is up to 40-fold higher than adult brain. Furthermore, ketones contribute uniquely to maturation within the nervous system (1-3, 9 -16).Most ketogenesis occurs in the liver and is driven primarily by rates of fatty acid oxidation. Mitochondrial fatty acid oxidation-derived acetoacetyl-CoA (AcAc-CoA) and acetyl-CoA together serve as the primary ketogenic substrates. Ketogenic reactions are sequentially catalyzed by HMG-CoA synthase 2 and HMG-CoA lyase, generating acetoacetate (AcAc), 3 which is converted to D-␤-hydroxybutyrate (␤OHB) in an NAD ϩ / NADH-coupled redox reaction catalyzed by ␤OHB dehydrogenase. AcAc and ␤OHB diffuse into the bloodstream and are delivered to ketolytic organs, in which they are exceptionally energy-efficient substrates (12,(17)(18)(19)(20)(21)(22). Within mitochondria of ketolytic organs, ␤OHB is oxidized back to AcAc in a reaction catalyzed by ␤OHB dehydrogenase. AcAc receives a CoA moiety from succinyl-CoA, generating AcAc-CoA in a reaction catalyzed by succinyl-CoA:3-oxo-acid CoA-transferase (SCOT, EC 2.8.3.5), encoded by nuclear Oxct1. This enzyme is not expressed in liver (12,23). Mitochondrial AcAc-CoA thiolase catalyzes conversion of AcAc-CoA to acetyl-CoA, which is terminally oxidized within the tricarboxylic acid cycle.Reports of ϳ20 individuals who harbor homozygous or compound heterozygous OXCT1 loss-of-function mutations (Online Mendelian Inheritance in Man 245050) indicate that a functional allele is required for ketone body oxidation, and as such patients t...

Background and objectivesImpacts of mindfulness-based programs on blood pressure remain equivocal, possibly because the programs are not adapted to engage with determinants of hypertension, or due to floor effects. Primary objectives were to create a customized Mindfulness-Based Blood Pressure Reduction (MB-BP) program, and to evaluate acceptability, feasibility, and effects on hypothesized proximal self-regulation mechanisms. Secondary outcomes included modifiable determinants of blood pressure (BP), and clinic-assessed systolic blood pressure (SBP).MethodsThis was a Stage 1 single-arm trial with one year follow-up. Focus groups and in-depth interviews were performed to evaluate acceptability and feasibility. Self-regulation outcomes, and determinants of BP, were assessed using validated questionnaires or objective assessments. The MB-BP curriculum was adapted from Mindfulness-Based Stress Reduction to direct participants’ mindfulness skills towards modifiable determinants of blood pressure.ResultsAcceptability and feasibility findings showed that of 53 eligible participants, 48 enrolled (91%). Of these, 43 (90%) attended at least 7 of the 10 MB-BP classes; 43 were followed to one year (90%). Focus groups (n = 19) and semi-structured interviews (n = 10) showed all participants viewed the delivery modality favorably, and identified logistic considerations concerning program access as barriers. A priori selected primary self-regulation outcomes showed improvements at one-year follow-up vs. baseline, including attention control (Sustained Attention to Response Task correct no-go score, p<0.001), emotion regulation (Difficulties in Emotion Regulation Score, p = 0.02), and self-awareness (Multidimensional Assessment of Interoceptive Awareness, p<0.001). Several determinants of hypertension were improved in participants not adhering to American Heart Association guidelines at baseline, including physical activity (p = 0.02), Dietary Approaches to Stop Hypertension-consistent diet (p<0.001), and alcohol consumption (p<0.001). Findings demonstrated mean 6.1 mmHg reduction in SBP (p = 0.008) at one year follow-up; effects were most pronounced in Stage 2 uncontrolled hypertensives (SBP≥140 mmHg), showing 15.1 mmHg reduction (p<0.001).ConclusionMB-BP has good acceptability and feasibility, and may engage with self-regulation and behavioral determinants of hypertension.