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International Journal of Molecular... Jun 2019The ketogenic diet (KD), a high-fat/low-carbohydrate/adequate-protein diet, has been proposed as a treatment for a variety of diseases, including cancer. KD leads to...
The ketogenic diet (KD), a high-fat/low-carbohydrate/adequate-protein diet, has been proposed as a treatment for a variety of diseases, including cancer. KD leads to generation of ketone bodies (KBs), predominantly acetoacetate (AcAc) and 3-hydroxy-butyrate, as a result of fatty acid oxidation. Several studies investigated the antiproliferative effects of lithium acetoacetate (LiAcAc) and sodium 3-hydroxybutyrate on cancer cells in vitro. However, a critical point missed in some studies using LiAcAc is that Li ions have pleiotropic effects on cell growth and cell signaling. Thus, we tested whether Li ions per se contribute to the antiproliferative effects of LiAcAc in vitro. Cell proliferation was analyzed on neuroblastoma, renal cell carcinoma, and human embryonic kidney cell lines. Cells were treated for 5 days with 2.5, 5, and 10 mM LiAcAc and with equimolar concentrations of lithium chloride (LiCl) or sodium chloride (NaCl). LiAcAc affected the growth of all cell lines, either negatively or positively. However, the effects of LiAcAc were always similar to those of LiCl. In contrast, NaCl showed no effects, indicating that the Li ion impacts cell proliferation. As Li ions have significant effects on cell growth, it is important for future studies to include sources of Li ions as a control.
Topics: Acetoacetates; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cells, Cultured; Chlorides; Gene Expression; Humans; Lithium; Lithium Chloride
PubMed: 31242642
DOI: 10.3390/ijms20123104 -
Frontiers in Endocrinology 2022Ketogenesis takes place in hepatocyte mitochondria where acetyl-CoA derived from fatty acid catabolism is converted to ketone bodies (KB), namely β-hydroxybutyrate... (Review)
Review
Ketogenesis takes place in hepatocyte mitochondria where acetyl-CoA derived from fatty acid catabolism is converted to ketone bodies (KB), namely β-hydroxybutyrate (β-OHB), acetoacetate and acetone. KB represent important alternative energy sources under metabolic stress conditions. Ketogenic diets (KDs) are low-carbohydrate, fat-rich eating strategies which have been widely proposed as valid nutritional interventions in several metabolic disorders due to its substantial efficacy in weight loss achievement. Carbohydrate restriction during KD forces the use of FFA, which are subsequently transformed into KB in hepatocytes to provide energy, leading to a significant increase in ketone levels known as "nutritional ketosis". The recent discovery of KB as ligands of G protein-coupled receptors (GPCR) - cellular transducers implicated in a wide range of body functions - has aroused a great interest in understanding whether some of the clinical effects associated to KD consumption might be mediated by the ketone/GPCR axis. Specifically, anti-inflammatory effects associated to KD regimen are presumably due to GPR109A-mediated inhibition of NLRP3 inflammasome by β-OHB, whilst lipid profile amelioration by KDs could be ascribed to the actions of acetoacetate GPR43 and of β-OHB GPR109A on lipolysis. Thus, this review will focus on the effects of KD-induced nutritional ketosis potentially mediated by specific GPCRs in metabolic and endocrinological disorders. To discriminate the effects of ketone bodies , independently of weight loss, only studies comparing ketogenic isocaloric non-ketogenic diets will be considered as well as short-term tolerability and safety of KDs.
Topics: Humans; Ketone Bodies; Acetoacetates; Diet, Ketogenic; 3-Hydroxybutyric Acid; Ketosis; Receptors, G-Protein-Coupled; Ketones; Carbohydrates; Weight Loss
PubMed: 36339405
DOI: 10.3389/fendo.2022.972890 -
NMR in Biomedicine Jun 2018The aim of this work was to investigate the use of C-labelled acetoacetate and β-hydroxybutyrate as novel hyperpolarized substrates in the study of cardiac metabolism....
The aim of this work was to investigate the use of C-labelled acetoacetate and β-hydroxybutyrate as novel hyperpolarized substrates in the study of cardiac metabolism. [1- C]Acetoacetate was synthesized by catalysed hydrolysis, and both it and [1- C]β-hydroxybutyrate were hyperpolarized by dissolution dynamic nuclear polarization (DNP). Their metabolism was studied in isolated, perfused rat hearts. Hyperpolarized [1- C]acetoacetate metabolism was also studied in the in vivo rat heart in the fed and fasted states. Hyperpolarization of [1- C]acetoacetate and [1- C]β-hydroxybutyrate provided liquid state polarizations of 8 ± 2% and 3 ± 1%, respectively. The hyperpolarized T values for the two substrates were 28 ± 3 s (acetoacetate) and 20 ± 1 s (β-hydroxybutyrate). Multiple downstream metabolites were observed within the perfused heart, including acetylcarnitine, citrate and glutamate. In the in vivo heart, an increase in acetylcarnitine production from acetoacetate was observed in the fed state, as well as a potential reduction in glutamate. In this work, methods for the generation of hyperpolarized [1- C]acetoacetate and [1- C]β-hydroxybutyrate were investigated, and their metabolism was assessed in both isolated, perfused rat hearts and in the in vivo rat heart. These preliminary investigations show that DNP can be used as an effective in vivo probe of ketone body metabolism in the heart.
Topics: 3-Hydroxybutyric Acid; Acetoacetates; Acetylcarnitine; Animals; Bicarbonates; Glutamic Acid; Ketone Bodies; Kinetics; Male; Metabolic Networks and Pathways; Metabolome; Myocardium; Perfusion; Rats; Rats, Wistar; Time Factors
PubMed: 29637642
DOI: 10.1002/nbm.3912 -
Free Radical Biology & Medicine Jun 2016Diets that boost ketone production are increasingly used for treating several neurological disorders. Elevation in ketones in most cases is considered favorable, as they... (Review)
Review
Diets that boost ketone production are increasingly used for treating several neurological disorders. Elevation in ketones in most cases is considered favorable, as they provide energy and are efficient in fueling the body's energy needs. Despite all the benefits from ketones, the above normal elevation in the concentration of ketones in the circulation tend to illicit various pathological complications by activating injurious pathways leading to cellular damage. Recent literature demonstrates a plausible link between elevated levels of circulating ketones and oxidative stress, linking hyperketonemia to innumerable morbid conditions. Ketone bodies are produced by the oxidation of fatty acids in the liver as a source of alternative energy that generally occurs in glucose limiting conditions. Regulation of ketogenesis and ketolysis plays an important role in dictating ketone concentrations in the blood. Hyperketonemia is a condition with elevated blood levels of acetoacetate, 3-β-hydroxybutyrate, and acetone. Several physiological and pathological triggers, such as fasting, ketogenic diet, and diabetes cause an accumulation and elevation of circulating ketones. Complications of the brain, kidney, liver, and microvasculature were found to be elevated in diabetic patients who had elevated ketones compared to those diabetics with normal ketone levels. This review summarizes the mechanisms by which hyperketonemia and ketoacidosis cause an increase in redox imbalance and thereby increase the risk of morbidity and mortality in patients.
Topics: Acetoacetates; Diabetes Mellitus, Type 1; Energy Metabolism; Glucose; Humans; Ketone Bodies; Ketones; Ketosis; Oxidative Stress; Risk Factors
PubMed: 27036365
DOI: 10.1016/j.freeradbiomed.2016.03.020 -
American Journal of Alzheimer's Disease... 2022The ketone bodies, especially the β-hydroxybutyrate, had been shown to modulate the function of the central nervous system and prevent the pathological progression of...
The ketone bodies, especially the β-hydroxybutyrate, had been shown to modulate the function of the central nervous system and prevent the pathological progression of Alzheimer's disease (AD). However, little is known about the role of acetoacetate in the AD brain. Thus, we intraventricularly injected acetoacetate into familial AD mice (APPSWE) for 14 days and monitored their memory and biochemical changes. During the behavior test, acetoacetate at 100 mg/kg led to significant improvement in both Y-maze and novel object recognition tests (NORTs) (both P < .05), indicating ameliorating spatial and recognition memory, respectively. Biomedical tests revealed two mechanisms were involved. Firstly, acetoacetate inhibited the GPR43-pERK pathway, which led to apparent inhibition in tumor necrosis factor-α and Interleukin-6 expression in the hippocampus in a concentration-dependent manner. Secondarily, acetoacetate stimulated the expression of hippocampal brain-derived neurotrophic factor (BDNF). We concluded that acetoacetate could ameliorate AD symptoms and exhibited promising features as a therapeutic for AD.
Topics: 3-Hydroxybutyric Acid; Acetoacetates; Alzheimer Disease; Animals; Brain-Derived Neurotrophic Factor; Disease Models, Animal; Inflammation; Interleukin-6; Mice; Tumor Necrosis Factor-alpha
PubMed: 36113018
DOI: 10.1177/15333175221124949 -
Journal of Lipid Research Aug 2023Acetoacetyl-CoA synthetase (AACS) is the key enzyme in the anabolic utilization of ketone bodies (KBs) for denovo lipid synthesis, a process that bypasses citrate and... (Review)
Review
Acetoacetyl-CoA synthetase (AACS) is the key enzyme in the anabolic utilization of ketone bodies (KBs) for denovo lipid synthesis, a process that bypasses citrate and ATP citrate lyase. This review shows that AACS is a highly regulated, cytosolic, and lipogenic enzyme and that many tissues can readily use KBs for denovo lipid synthesis. AACS has a low micromolar K for acetoacetate, and supply of acetoacetate should not limit its activity in the fed state. In many tissues, AACS appears to be regulated in conjunction with the need for cholesterol, but in adipose tissue, it seems tied to fatty acid synthesis. KBs are readily utilized as substrates for lipid synthesis in lipogenic tissues, including liver, adipose tissue, lactating mammary gland, skin, intestinal mucosa, adrenals, and developing brain. In numerous studied cases, KBs served several-fold better than glucose as substrates for lipid synthesis, and when present, KBs suppressed the utilization of glucose for lipid synthesis. Here, it is hypothesized that a physiological role for the utilization of KBs for lipid synthesis is a metabolic process of lipid interconversion. Fatty acids are converted to KBs in liver, and then, the KBs are utilized to synthesize cholesterol and other long-chain fatty acids in liver and nonhepatic tissues. The conversion of fatty acids to cholesterol via the KBs may be a particularly important example of lipid interconversion. Utilizing KBs for lipid synthesis is glucose sparing and probably is important with low carbohydrate diets. Metabolic situations and tissues where this pathway may be important are discussed.
Topics: Female; Humans; Acetoacetates; Lactation; Ketone Bodies; Fatty Acids; Liver; Cholesterol; Glucose
PubMed: 37356666
DOI: 10.1016/j.jlr.2023.100407 -
ACS Sensors Nov 2021Cellular redox is intricately linked to energy production and normal cell function. Although the redox states of mitochondria and cytosol are connected by shuttle...
Cellular redox is intricately linked to energy production and normal cell function. Although the redox states of mitochondria and cytosol are connected by shuttle mechanisms, the redox state of mitochondria may differ from redox in the cytosol in response to stress. However, detecting these differences in functioning tissues is difficult. Here, we employed C magnetic resonance spectroscopy (MRS) and co-polarized [1-C]pyruvate and [1,3-C]acetoacetate ([1,3-C]AcAc) to monitor production of hyperpolarized (HP) lactate and β-hydroxybutyrate as indicators of cytosolic and mitochondrial redox, respectively. Isolated rat hearts were examined under normoxic conditions, during low-flow ischemia, and after pretreatment with either aminooxyacetate (AOA) or rotenone. All interventions were associated with an increase in [P]/[ATP] measured by P NMR. In well-oxygenated untreated hearts, rapid conversion of HP [1-C]pyruvate to [1-C]lactate and [1,3-C]AcAc to [1,3-C]β-hydroxybutyrate ([1,3-C]β-HB) was readily detected. A significant increase in HP [1,3-C]β-HB but not [1-C]lactate was observed in rotenone-treated and ischemic hearts, consistent with an increase in mitochondrial NADH but not cytosolic NADH. AOA treatments did not alter the productions of HP [1-C]lactate or [1,3-C]β-HB. This study demonstrates that biomarkers of mitochondrial and cytosolic redox may be detected simultaneously in functioning tissues using co-polarized [1-C]pyruvate and [1,3-C]AcAc and C MRS and that changes in mitochondrial redox may precede changes in cytosolic redox.
Topics: Acetoacetates; Animals; Cytosol; Lactic Acid; Mitochondria; Oxidation-Reduction; Pyruvic Acid; Rats
PubMed: 34761912
DOI: 10.1021/acssensors.1c01225 -
Brain : a Journal of Neurology Jan 2024Alterations in brain energy metabolism have long been proposed as one of several neurobiological processes contributing to delirium. This is supported by previous...
Alterations in brain energy metabolism have long been proposed as one of several neurobiological processes contributing to delirium. This is supported by previous findings of altered CSF lactate and neuron-specific enolase concentrations and decreased glucose uptake on brain-PET in patients with delirium. Despite this, there are limited data on metabolic alterations found in CSF samples, and targeted metabolic profiling of CSF metabolites involved in energy metabolism has not been performed. The aim of the study was to investigate whether metabolites related to energy metabolism in the serum and CSF of patients with hip fracture are associated with delirium. The study cohort included 406 patients with a mean age of 81 years (standard deviation 10 years), acutely admitted to hospital for surgical repair of a hip fracture. Delirium was assessed daily until the fifth postoperative day. CSF was collected from all 406 participants at the onset of spinal anaesthesia, and serum samples were drawn concurrently from 213 participants. Glucose and lactate in CSF were measured using amperometry, whereas plasma glucose was measured in the clinical laboratory using enzymatic photometry. Serum and CSF concentrations of the branched-chain amino acids, 3-hydroxyisobutyric acid, acetoacetate and β-hydroxybutyrate were measured using gas chromatography-tandem mass spectrometry (GC-MS/MS). In total, 224 (55%) patients developed delirium pre- or postoperatively. Ketone body concentrations (acetoacetate, β-hydroxybutyrate) and branched-chain amino acids were significantly elevated in the CSF but not in serum among patients with delirium, despite no group differences in glucose concentrations. The level of 3-hydroxyisobutyric acid was significantly elevated in both CSF and serum. An elevation of CSF lactate during delirium was explained by age and comorbidity. Our data suggest that altered glucose utilization and a shift to ketone body metabolism occurs in the brain during delirium.
Topics: Humans; Aged, 80 and over; Glucose; Acetoacetates; 3-Hydroxybutyric Acid; Delirium; Tandem Mass Spectrometry; Hip Fractures; Brain; Lactates; Amino Acids, Branched-Chain
PubMed: 37658825
DOI: 10.1093/brain/awad296 -
The Journal of Biological Chemistry May 2003Three sequential phases of mitochondrial calcium accumulation can be distinguished: matrix dehydrogenase regulation, buffering of extramitochondrial free calcium, and...
Three sequential phases of mitochondrial calcium accumulation can be distinguished: matrix dehydrogenase regulation, buffering of extramitochondrial free calcium, and finally activation of the permeability transition. Relationships between these phases, free and total matrix calcium concentration, and phosphate concentration are investigated in rat liver and brain mitochondria. Slow, continuous calcium infusion is employed to avoid transient bioenergetic consequences of bolus additions. Liver and brain mitochondria undergo permeability transitions at precise matrix calcium loads that are independent of infusion rate. Cytochrome c release precedes the permeability transition. Cyclosporin A enhances the loading capacity in the presence or absence of acetoacetate. A remarkably constant free matrix calcium concentration, in the range 1-5 microM as monitored by matrix-loaded fura2-FF, was observed when total matrix calcium was increased from 10 to at least 500 nmol of calcium/mg of protein. Increasing phosphate decreased both the free matrix calcium and the matrix calcium-loading capacity. Thus the permeability transition is not triggered by a critical matrix free calcium concentration. The rate of hydrogen peroxide detection by Amplex Red decreased during calcium infusion arguing against a role for oxidative stress in permeability pore activation in this model. A transition between a variable and buffered matrix free calcium concentration occurred at 10 nmol of total matrix calcium/mg protein. The solubility product of amorphous Ca3(PO4)2 is consistent with the observed matrix free calcium concentration, and the matrix pH is proposed to play the major role in maintaining the low matrix free calcium concentration.
Topics: Acetoacetates; Adenosine Diphosphate; Animals; Brain; Calcium; Calcium Phosphates; Cell Membrane Permeability; Cyclosporine; Cytochrome c Group; Fluorescence; Fluorescent Dyes; Fura-2; Hydrogen Peroxide; Kinetics; Light; Membrane Potentials; Mitochondria; Mitochondria, Liver; NAD; NADP; Oxidation-Reduction; Oxidative Stress; Phosphates; Rats; Rats, Wistar; Scattering, Radiation; Solubility
PubMed: 12660243
DOI: 10.1074/jbc.M212661200 -
The Journal of Nutrition, Health & Aging Jan 2015The brain is one of the most energy-demanding organs in the body. It has evolved intricate metabolic networks to fulfill this need and utilizes a variety of substrates... (Review)
Review
The brain is one of the most energy-demanding organs in the body. It has evolved intricate metabolic networks to fulfill this need and utilizes a variety of substrates to generate ATP, the universal energy currency. Any disruption in the supply of energy results in various abnormalities including Alzheimer's disease (AD), a condition with markedly diminished cognitive ability. Astrocytes are an important participant in maintaining the cerebral ATP budget. However, under oxidative stress induced by numerous factors including aluminum toxicity, the ability of astroctyes to generate ATP is impaired due to dysfunctional mitochondria. This leads to globular, glycolytic, lipogenic and ATP-deficient astrocytes, cerebral characteristics common in AD patients. The reversal of these perturbations by such natural metabolites as pyruvate, α-ketoglutarate, acetoacetate and L-carnitine provides valuable therapeutic cues against AD.
Topics: Acetoacetates; Adenosine Triphosphate; Aluminum; Alzheimer Disease; Astrocytes; Brain; Carnitine; Humans; Ketoglutaric Acids; Mitochondria; Oxidative Stress; Pyruvic Acid
PubMed: 25560817
DOI: 10.1007/s12603-014-0511-7