scholarly journals Activities of enzymes involved in acetoacetate utilization in adult mammalian tissues

1971 ◽  
Vol 121 (1) ◽  
pp. 41-47 ◽  
Author(s):  
D. H. Williamson ◽  
Margaret W. Bates ◽  
M. Ann Page ◽  
H. A. Krebs
Keyword(s):  
Ketone Body ◽  
Alloxan Diabetes ◽  
Adrenal Glands ◽  
Ketone Bodies ◽  
Rat Tissues ◽  
Adult Rat ◽  
Coa Transferase ◽  
Mammalian Tissues ◽  
Fat Feeding ◽  
Low Activity

1. The activities in rat tissues of 3-oxo acid CoA-transferase (the first enzyme involved in acetoacetate utilization) were found to be highest in kidney and heart. In submaxillary and adrenal glands the activities were about one-quarter of those in kidney and heart. In brain it was about one-tenth and was less in lung, spleen, skeletal muscle and epididymal fat. No activity was detectable in liver. 2. The activities of acetoacetyl-CoA thiolase were found roughly to parallel those of the transferase except for liver and adrenal glands. The high activity in the latter two tissues may be explained by additional roles of thiolase, namely, the production of acetyl-CoA from fatty acids. 3. The activities of the two enzymes in tissues of mouse, gerbil, golden hamster, guinea pig and sheep were similar to those of rat tissues. The notable exception was the low activity of the transferase and thiolase in sheep heart and brain. 4. The activities of the transferase in rat tissues did not change appreciably in starvation, alloxan-diabetes or on fat-feeding, where the rates of ketone-body utilization are increased. Thiolase activity increased in kidney and heart on fat-feeding. 5. The activity of 3-hydroxybutyrate dehydrogenase did not change in rat brain during starvation. 6. The factors controlling the rate of ketone-body utilization are discussed. It is concluded that the activities of the relevant enzymes in the adult rat do not control the variations in the rate of ketone-body utilization that occur in starvation or alloxan-diabetes. The controlling factor in these situations is the concentration of the ketone bodies in plasma and tissues.

scholarly journals Activities of enzymes of ketone-body utilization in brain and other tissues of suckling rats

1971 ◽  
Vol 121 (1) ◽  
pp. 49-53 ◽  
Author(s):  
M. Ann Page ◽  
H. A. Krebs ◽  
D. H. Williamson
Keyword(s):  
Rat Brain ◽  
Ketone Body ◽  
Ketone Bodies ◽  
Rat Kidney ◽  
Adult Brain ◽  
Suckling Period ◽  
Suckling Rats ◽  
Adult Rat ◽  
Coa Transferase ◽  
High Concentrations

1. The activities of 3-hydroxybutyrate dehydrogenase and 3-oxo acid CoA-transferase in rat brain at birth were found to be about two-thirds of those of adult rat brain, expressed per g wet wt. The activities rose throughout the suckling period and at the time of weaning reached values about three times higher than those for adult brain. Later they gradually declined. 2. At birth the activity of acetoacetyl-CoA thiolase in rat brain was about 60% higher than in the adult. During the suckling period there was no significant change in activity. 3. In rat kidney the activities of the three enzymes at birth were less than one-third of those at maturity. They gradually rose and after 5 weeks approached the adult value. Similar results were obtained with rat heart. 4. The activity of glutamate dehydrogenase (a mitochondrial enzyme like 3-hydroxybutyrate dehydrogenase and 3-oxo acid CoA-transferase) also rose in brain and kidney during the suckling period, but at no stage did it exceed the adult value. 5. Throughout the suckling period the total ketone-body concentration in the blood was about six times higher than in adult fed rats, and the concentration of free fatty acids in the blood was three to four times higher. 6. It is concluded that the rate of ketone-body utilization in brains of suckling rats is determined by both the greater amounts of the key enzymes in the tissue and the high concentrations of ketone bodies in the blood. In addition, the low activities of the relevant enzymes in kidney and heart of suckling rats may make available more ketone bodies for the brain.

P3476High-resolution respirometry reveals enhanced myocardial mitochondrial ketone oxidation after fasting and ventricular unloading

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
E Zweck ◽  
V Burkart ◽  
C Wessel ◽  
D Scheiber ◽  
K H M Leung ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ketone Body ◽  
Ketone Bodies ◽  
Ex Vivo ◽  
Oxidative Capacity ◽  
Left Ventricular ◽  
University Hospital ◽  
Oxygen Flux ◽  
Protective Effects ◽  
Coa Transferase

Abstract Background Impairment of myocardial mitochondrial function is regarded as an established pathomechanism in heart failure. Enhanced oxidation of ketone bodies may potentially exert protective effects on myocardial function. High-resolution respirometry (HRR) resembles a gold-standard methodology to determine myocardial mitochondrial metabolism and oxidative function but has not been validated for ketone substrates yet. Purpose We hypothesized that (1) quantification of ketone body oxidative capacity (OC) in myocardium utilizing ex-vivo HRR is feasible and that (2) ketone-associated OC is elevated after fasting and under conditions of chronic mechanical ventricular unloading. Methods We established new HRR (Oxygraph-2k) protocols, measuring oxygen flux generated by oxidation of the ketone substrates beta-hydroxybutyrate (HBA) and acetoacetate (ACA). Ketone protocols were then applied to twelve C57BL/6 mice' (of which six were fasted for 16h) left ventricular and right liver lobe tissue, as well as to eleven terminal heart failure patients' left ventricular tissue, harvested at heart transplantation. Heart transplant recipients were subdivided into patients with left ventricular assist device prior to transplantation (LVAD group, n=6) or no unloading prior to transplantation (HTX group, n=5). Results In non-fasted rodent hearts, HBA yielded an OC of 25±4 pmol/(s*mg tissue) above basal respiration, when applied as sole substrate (21±11 pmol/(s*mg) in liver). ACA alone did not induce oxygen flux, but ACA+succinate yielded 229% higher oxygen flux than succinate alone in state III (146±32 vs 44±12 pmol/(s*mg); p=0.0003). When titrated after succinate, ACA increased OC by 93±25 pmol/(s*mg) (p=0.0003). In 16h-fasted rodent hearts, HBA-supported OC was 27% higher (41±3 vs 52±9 pmol/(s*mg); p=0.04), while OC with ACA+succinate was unchanged (p=0.60). In rodent liver, no oxygen flux was induced by ACA, reflecting absence of 3-oxoacid CoA-transferase. However, HBA-supported OC was 118% higher in fasted liver (37±13 vs 57±13 pmol/(s*mg); p=0.03). In humans, left ventricular unloading was not associated with altered myocardial OC for fatty acids and glycolytic substrates (standard protocol, p=0.13), but HBA-supported OC was 39% higher in the LVAD group compared to the HTX group (54±12 vs 39±9 pmol/(s*mg), p=0.04). Conclusion Quantification of ketone body OC with HRR is feasible in permeabilized myocardial fibers. Applying this novel method revealed increased HBA-supported myocardial mitochondrial respiration after fasting and chronic left ventricular unloading. These data support a concept of enhanced ketone oxidation following ventricular unloading in myocardial mitochondria. Our findings facilitate new studies on myocardial ketone turnover and the interaction of mitochondrial ketone metabolism with cardiac performance. Acknowledgement/Funding CRC 1116, Research commission of the University Hospital Düsseldorf

scholarly journals Cloning of rat brain succinyl-CoA:3-oxoacid CoA-transferase cDNA. Regulation of the mRNA in different rat tissues and during brain development

1987 ◽  
Vol 248 (3) ◽  
pp. 853-857 ◽  
Author(s):  
M K Ganapathi ◽  
M Kwon ◽  
P M Haney ◽  
C McTiernan ◽  
A A Javed ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Rat Brain ◽  
Ketone Bodies ◽  
Rat Kidney ◽  
Relative Rate ◽  
Cdna Clones ◽  
Rat Tissues ◽  
Transferase Activity ◽  
Coa Transferase ◽  
Old Rats

3-Oxoacid CoA-transferase, which catalyses the first committed step in the oxidation of ketone bodies, is uniquely regulated in developing rat brain. Changes in 3-oxoacid CoA-transferase activity in rat brain during the postnatal period are due to changes in the relative rate of synthesis of the enzyme. To study the regulation of this enzyme, we identified, with a specific polyclonal rabbit anti-(rat 3-oxoacid CoA-transferase), two positive cDNA clones (approx. 800 bp) in a lambda gtll expression library, constructed from poly(A)+ RNA from brains of 12-day-old rats. One of these clones (lambda CoA3) was subcloned into M13mp18 and subjected to further characterization. Labelled single-stranded probes prepared by primer extension of the M13mp18 recombinant hybridized to a 3.6 kb mRNA. Rat brain mRNA enriched by polysome immunoadsorption for a single protein of size 60 kDa which corresponds to the precursor form of 3-oxoacid CoA-transferase was also found to be similarly enriched for the hybridizable 3.6 kb mRNA complementary to lambda CoA3. Affinity-selected antibody to the lambda CoA3 fusion protein inhibited 3-oxoacid CoA-transferase activity present in rat brain mitochondrial extracts. The 3.6 kb mRNA for 3-oxoacid CoA-transferase was present in relative abundance in rat kidney and heart, to a lesser extent in suckling brain and mammary gland and negligible in the liver. The specific mRNA was also found to be 3-fold more abundant in the brain from 12-day-old rats as compared with 18-day-old foetuses and adult rats, corresponding to the enzyme activity and relative rate of synthesis profile during development. These data suggest that 3-oxoacid CoA-transferase enzyme activity is regulated at a pretranslational level.

scholarly journals Turnover rates of ketone bodies in normal, starved and alloxan-diabetic rats

1968 ◽  
Vol 110 (4) ◽  
pp. 655-661 ◽  
Author(s):  
Margaret W. Bates ◽  
H. A. Krebs ◽  
D. H. Williamson
Keyword(s):  
Ketone Body ◽  
Alloxan Diabetes ◽  
Ketone Bodies ◽  
Diabetic Rats ◽  
Turnover Rates ◽  
Blood Concentrations ◽  
Order Of Magnitude ◽  
The Mean ◽  
Body Production ◽  
Body Concentration

1. Rates of appearance and disappearance of total ketone bodies were determined in normal, starved and alloxan-diabetic rats by measuring specific radioactivities and concentrations of blood acetoacetate and 3-hydroxybutyrate at different times after injection of 3-hydroxy[14C]butyrate. 2. The mean rates of appearance were 1·7, 4·2 and 10·9μmoles/min./100g. body wt. respectively for normal, starved and alloxan-diabetic rats. The rates of disappearance were of the same order of magnitude as the rates of appearance. 3. There was a direct correlation between the rates of appearance and disappearance and the blood concentrations of the ketone bodies. 4. The results indicate that in the rat increased ketone-body production is paralleled by increased ketone-body utilization and that the raised ketone-body concentration in the blood in starvation and alloxan-diabetes is due to a slight imbalance between the rates of production and utilization. 5. The findings are discussed in relation to the concept that ketone bodies can serve as fuels of respiration when the supply of carbohydrate is limited.

scholarly journals The heterogeneity of arginases in rat tissues

1976 ◽  
Vol 153 (2) ◽  
pp. 469-478 ◽  
Author(s):  
A Herzfeld ◽  
S M Raper
Keyword(s):  
Submaxillary Gland ◽  
Assay Method ◽  
Heat Sensitivity ◽  
Rat Tissues ◽  
Sensitive Assay ◽  
Adult Rat ◽  
Liver And Kidney ◽  
Moving Band ◽  
Low Activity ◽  
Different Tissues

Arginase reactions in rat tissues were shown to be catalysed by three isoenzymes which can be separated by bidirectional electrophoresis on polyacrylamide gels. Anodic electrophoresis reveals a migrating band (isoenzyme I) present in all-non-hepatic tissues except submaxillary gland and a non-migrating band found in all tissues. The latter is resolved by cathodic electrophoresis into isoenzymes III (characteristic of liver and submaxillary gland) and a non-moving band (isoenzyme II), present in kidney, intestine and pancreas. Sequential electrophoresis, in the two directions, of mixture of liver and kidney extracts in the same gel columns separated all three isoenzymes. Differences in the solubilization properties, heat-sensitivity and substrate specificity of arginases from different tissues could be correlated with their electrophoretic behaviour. L-Canavanine could replace arginine as substrate in extracts of kidney but not of liver. Both kidney isoenzymes hydrolysed L-canavanine equally well, whereas isoenzyme III from submaxillary gland showed only very low activity. Antiserum against liver arginase interacted with the enzyme with submaxillary gland, but did not inactivate or adsorb arginase from kidney, intestine or pancreas. The distribution of arginase among 16 normal adult rat tissues is presented; the improved, sensitive, assay method was applicable to tissues containing as little as 0.1% of the hepatic activity.

scholarly journals A high-MUFA diet alone does not affect ketone body metabolism, but reduces glycated hemoglobin when combined with exercise training in diabetic rats

2017 ◽  
Vol 9 (1) ◽  
pp. 31-40
Author(s):  
Juraiporn Somboonwong ◽  
Khunkhong Huchaiyaphum ◽  
Onanong Kulaputana ◽  
Phisit Prapunwattana
Keyword(s):  
Exercise Training ◽  
Ketone Body ◽  
Glycated Hemoglobin ◽  
Ketone Bodies ◽  
Transferase Activity ◽  
Nonesterified Fatty Acids ◽  
Regular Diet ◽  
Coa Transferase ◽  
Ketone Body Metabolism ◽  
Mufa Diet

Abstract Background Monounsaturated fat (MUFA) also has glucose-lowering action, but its effect on ketone bodies is unknown. Objectives To examine the effects of high-MUFA diet alone or in combination with exercise training, which can improve glucose and ketone body metabolism, in a rat model of diabetes. Methods Wistar rats were administered streptozotocin to induce diabetes and then randomly divided into five groups: sedentary rats fed a regular diet (1), a high-saturated-fat diet (2), a high-MUFA diet (3); and exercisetrained rats fed a regular diet (4), and a high-MUFA diet (5). Training was by a treadmill twice daily, 5 days/week. At 12 weeks, glucose, glycated hemoglobin (HbA1c), insulin, nonesterified fatty acids (NEFA), and β-hydroxybutyrate levels were measured in cardiac blood. Activity of the overall ketone synthesis pathway was determined in liver and 3-ketoacyl-CoA transferase activity determined in gastrocnemius muscle. Results A high-MUFA diet tended to lower plasma glucose without affecting other biochemical variables. Training did not change glucose metabolism, but significantly reduced serum NEFA. Only the high-MUFA diet plus training significantly decreased HbA1c levels. Hepatic ketone synthesis was decreased and 3-ketoacyl-CoA transferase activity was increased by training alone or in combination with a high-MUFA diet. Changes in NEFA, β-hydroxybutyrate, and the enzymatic activities in response to training plus a high-MUFA diet were comparable to those caused by training alone. Conclusion A high-MUFA diet alone does not alter ketone body metabolism. Combination of a MUFA-rich diet and exercise training is more effective than either MUFA or exercise alone for lowering HbA1c.

scholarly journals Differential Response of Hippocampal and Cerebrocortical Autophagy and Ketone Body Metabolism to the Ketogenic Diet

2021 ◽  
Vol 15 ◽  
Author(s):  
Daniela Liśkiewicz ◽  
Arkadiusz Liśkiewicz ◽  
Marta M. Nowacka-Chmielewska ◽  
Mateusz Grabowski ◽  
Natalia Pondel ◽  
...  
Keyword(s):  
Frontal Cortex ◽  
Ketogenic Diet ◽  
Ketone Body ◽  
Brain Aging ◽  
Ketone Bodies ◽  
Monocarboxylate Transporter ◽  
Proper Function ◽  
Monocarboxylate Transporter 1 ◽  
Coa Transferase ◽  
Ketone Body Metabolism

Experimental and clinical data support the neuroprotective properties of the ketogenic diet and ketone bodies, but there is still a lot to discover to comprehensively understand the underlying mechanisms. Autophagy is a key mechanism for maintaining cell homeostasis, and therefore its proper function is necessary for preventing accelerated brain aging and neurodegeneration. Due to many potential interconnections, it is possible that the stimulation of autophagy may be one of the mediators of the neuroprotection afforded by the ketogenic diet. Recent studies point to possible interconnections between ketone body metabolism and autophagy. It has been shown that autophagy is essential for hepatic and renal ketogenesis in starvation. On the other hand, exogenous ketone bodies modulate autophagy both in vitro and in vivo. Many regional differences occur between brain structures which concern i.e., metabolic responses and autophagy dynamics. The aim of the present study was to evaluate the influence of the ketogenic diet on autophagic markers and the ketone body utilizing and transporting proteins in the hippocampus and frontal cortex. C57BL/6N male mice were fed with two ketogenic chows composed of fat of either animal or plant origins for 4 weeks. Markers of autophagosome formation as well as proteins associated with ketolysis (BDH1—3-hydroxybutyrate dehydrogenase 1, SCOT/OXCT1—succinyl CoA:3-oxoacid CoA transferase), ketone transport (MCT1—monocarboxylate transporter 1) and ketogenesis (HMGCL, HMGCS2) were measured. The hippocampus showed a robust response to nutritional ketosis in both changes in the markers of autophagy as well as the levels of ketone body utilizing and transporting proteins, which was also accompanied by increased concentrations of ketone bodies in this brain structure, while subtle changes were observed in the frontal cortex. The magnitude of the effects was dependent on the type of ketogenic diet used, suggesting that plant fats may exert a more profound effect on the orchestrated upregulation of autophagy and ketone body metabolism markers. The study provides a foundation for a deeper understanding of the possible interconnections between autophagy and the neuroprotective efficacy of nutritional ketosis.

scholarly journals Activities of hexokinase, phosphofructokinase, 3-oxo acid coenzyme A-transferase and acetoacetyl-coenzyme A thiolase in nervous tissue from vertebrates and invertebrates

1973 ◽  
Vol 134 (1) ◽  
pp. 97-101 ◽  
Author(s):  
P. H. Sugden ◽  
E. A. Newsholme
Keyword(s):  
Nervous Tissue ◽  
Ketone Body ◽  
Glucose Utilization ◽  
Coenzyme A ◽  
Ketone Bodies ◽  
Animal Kingdom ◽  
Coa Transferase ◽  
Utilization Pathway ◽  
The Brain

1. The maximum activities of hexokinase and phosphofructokinase in nervous tissue from 18 different animals from different phyla range from 5.1 to 17.6 and from 24.0μmol/min per g fresh wt. respectively. In any one tissue the activities of these two enzymes are, in general, very similar. The rate of glucose utilization by the brain in vivo is much lower than the activities of hexokinase or phosphofructokinase. It is suggested that the high activities of these enzymes indicate a capacity for glycolysis which may be used by the brain during hypoxia or during conditions of extreme neuronal activity. 2. The activities of 3-oxo acid CoA-transferase and acetoacetyl-CoA thiolase in the nervous tissues range from 1.1 to 15.3 and from 0.7 to 4.5μmol/min per g fresh wt. respectively. Unfortunately the activities of these enzymes cannot be used to estimate maximal flux through the ketone-body-utilization pathway, since they may catalyse reactions that are close to equilibrium. Nonetheless, the presence of these enzymes in nervous tissue from a large variety of animals suggests that the importance of ketone bodies as a fuel for nervous tissue may be widespread in the animal kingdom.

scholarly journals Successful adaptation to ketosis by mice with tissue-specific deficiency of ketone body oxidation

2013 ◽  
Vol 304 (4) ◽  
pp. E363-E374 ◽  
Author(s):  
David G. Cotter ◽  
Rebecca C. Schugar ◽  
Anna E. Wentz ◽  
D. André d'Avignon ◽  
Peter A. Crawford
Keyword(s):  
Ketone Body ◽  
Neonatal Period ◽  
Ketone Bodies ◽  
Fatty Acyl ◽  
Carbohydrate Intake ◽  
Tissue Specific ◽  
Neonatal Mice ◽  
Coa Transferase ◽  
Low Carbohydrate ◽  
Ketone Body Metabolism

During states of low carbohydrate intake, mammalian ketone body metabolism transfers energy substrates originally derived from fatty acyl chains within the liver to extrahepatic organs. We previously demonstrated that the mitochondrial enzyme coenzyme A (CoA) transferase [succinyl-CoA:3-oxoacid CoA transferase (SCOT), encoded by nuclear Oxct1] is required for oxidation of ketone bodies and that germline SCOT-knockout (KO) mice die within 48 h of birth because of hyperketonemic hypoglycemia. Here, we use novel transgenic and tissue-specific SCOT-KO mice to demonstrate that ketone bodies do not serve an obligate energetic role within highly ketolytic tissues during the ketogenic neonatal period or during starvation in the adult. Although transgene-mediated restoration of myocardial CoA transferase in germline SCOT-KO mice is insufficient to prevent lethal hyperketonemic hypoglycemia in the neonatal period, mice lacking CoA transferase selectively within neurons, cardiomyocytes, or skeletal myocytes are all viable as neonates. Like germline SCOT-KO neonatal mice, neonatal mice with neuronal CoA transferase deficiency exhibit increased cerebral glycolysis and glucose oxidation, and, while these neonatal mice exhibit modest hyperketonemia, they do not develop hypoglycemia. As adults, tissue-specific SCOT-KO mice tolerate starvation, exhibiting only modestly increased hyperketonemia. Finally, metabolic analysis of adult germline Oxct1+/− mice demonstrates that global diminution of ketone body oxidation yields hyperketonemia, but hypoglycemia emerges only during a protracted state of low carbohydrate intake. Together, these data suggest that, at the tissue level, ketone bodies are not a required energy substrate in the newborn period or during starvation, but rather that integrated ketone body metabolism mediates adaptation to ketogenic nutrient states.

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