Turnover and precursor-product relationships of nonlipid metabolites.

Hetenyi, G; Perez, G. R.; Vranić, Mladen

doi:10.1152/physrev.1983.63.2.606

Cited by 80 publications

(35 citation statements)

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“…The decrease in plasma FFA oxidation in the HI group by exercise is paralleled by a significant decrease of the R a of FFA in plasma. Together with the decrease of plasma FFA and glycerol concentration seen after exercise training (P Ͻ 0.05), this seems to point to a reduced rate of adipose tissue lipolysis in the HI group (15).…”

Section: Discussionmentioning

confidence: 78%

Effect of exercise training at different intensities on fat metabolism of obese men

Aggel-Leijssen

Saris

Wagenmakers

et al. 2002

Journal of Applied Physiology

111

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. Effect of exercise training at different intensities on fat metabolism of obese men. J Appl Physiol 92: 1300-1309, 2002; 10.1152/japplphysiol.00030.2001.-The present study investigated the effect of exercise training at different intensities on fat oxidation in obese men. Twenty-four healthy male obese subjects were randomly divided in either a low-[40% maximal oxygen consumption (V O2 max)] or high-intensity exercise training program (70% V O2 max) for 12 wk, or a nonexercising control group. Before and after the intervention, measurements of fat metabolism at rest and during exercise were performed by using indirect calorimetry, [U-13 C]palmitate, and [1,2-13 C]acetate. Furthermore, body composition and maximal aerobic capacity were measured. Total fat oxidation did not change at rest in any group. During exercise, after low-intensity exercise training, fat oxidation was increased by 40% (P Ͻ 0.05) because of an increased non-plasma fatty acid oxidation (P Ͻ 0.05). Highintensity exercise training did not affect total fat oxidation during exercise. Changes in fat oxidation were not significantly different among groups. It was concluded that lowintensity exercise training in obese subjects seemed to increase fat oxidation during exercise but not at rest. No effect of high-intensity exercise training on fat oxidation could be shown. low intensity; stable isotopes; acetate correction factor; [ 13 C]palmitate OBESITY IS ASSOCIATED with an impaired ability to use fat as a fuel. This may contribute to the development and maintenance of large fat stores. Upper body obesity is associated with an impaired postabsorptive free fatty acid (FFA) utilization in skeletal muscle in women (6). Isoprenaline-induced fat oxidation and skeletal muscle FFA uptake are impaired in obese men, and no improvement was found after weight loss (1-3). Lean, formerly obese women have lower fasting fat oxidation rates compared with lean, never-obese women (32). Moreover, in Pima Indians, a population with a high prevalence of obesity, weight gain is association with a low 24-h fat-to-carbohydrate oxidation ratio (49). Several explanations have been proposed for this reduced fat utilization in obesity, such as a low activity of enzymes of ␤-oxidation (50), low skeletal muscle lipoprotein lipase activity (7), and impaired mobilization of fat stores (1). Interventions that will increase the capacity of the skeletal muscle to utilize fat may, therefore, make an important contribution to weight management in obese individuals and individuals at risk for obesity.Endurance exercise training is known to increase fat oxidation during submaximal exercise at a fixed workload in lean subjects (14,17,23,30,38). Cross-sectional studies also report higher fat oxidation during exercise after an overnight fast (18,20,21,40,45) or with glucose (19, 47) in trained compared with sedentary men. Some studies also found an enhanced resting fat oxidation after endurance training (5, 31, 34). Thus endurance exercise training appears to have the capacity to increase ...

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Section: Discussionmentioning

confidence: 78%

Effect of exercise training at different intensities on fat metabolism of obese men

Aggel-Leijssen

Saris

Wagenmakers

et al. 2002

Journal of Applied Physiology

111

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“…Thus, elevations in corticosterone appear to act through the GR to regulate the availability of lipid energy substrates, thereby ensuring that energy metabolism is balanced in response to changing energy requirements (McEwen, 2000). Because RU486 did not affect plasma glycerol, which is a general indicator of lipolysis (Hetenyi et al, 1983), corticosterone does not appear to increase free fatty acid availability through the breakdown of lipid stores. Catecholamines and/or growth hormone may play a more dominant role in this process (Hadley, 1999).…”

Section: The Role Of Corticosterone During An Energetic Challengementioning

confidence: 98%

The low-affinity glucocorticoid receptor regulates feeding and lipid breakdown in the migratory Gambel's white-crowned sparrowZonotrichia leucophrys gambelii

Landys

Ramenofsky

Guglielmo

et al. 2004

Journal of Experimental Biology

114

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Plasma corticosterone increases during spring migration in a variety of bird species, including the Gambel's white-crowned sparrow Zonotrichia leucophrys gambelii. Corticosterone is elevated specifically in association with migratory flight, suggesting that corticosterone may promote processes such as energy mobilization and/or migratory activity. General effects of glucocorticoids support such a prediction. Because glucocorticoids exert permissive effects on food intake, corticosterone may also participate in the regulation of migratory hyperphagia. To examine the role of corticosterone during migration, we induced Gambel's white-crowned sparrows to enter the migratory condition and compared food intake and locomotor activity between controls and birds injected with RU486 -an antagonist to the low-affinity glucocorticoid receptor (GR). In addition, we investigated effects of RU486 in birds that were subjected to a short-term fast. Results indicate that RU486 did not affect locomotor activity. However, consistent with its effects in mammals, RU486 suppressed food intake. Thus, hyperphagia and migratory restlessness, the two behaviors that characterize migration, may be regulated by different mechanisms. Lastly, RU486 antagonized fasting-induced lipid mobilization, as evidenced by decreased plasma free fatty acids. Thus, data on spring migrants suggest that endogenous corticosterone levels act through the GR to support hyperphagia and that the GR promotes availability of lipid fuel substrates in association with periods of energetic demand, e.g. during migratory flight.

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“…Circulating glycerol originates primarily from adipose tissue as a result of the breakdown of stored triglycerides (1,2). In hu-version to glucose (2)(3)(4).…”

Section: Introductionmentioning

confidence: 99%

Increased lipolysis and its consequences on gluconeogenesis in non-insulin-dependent diabetes mellitus.

Nurjhan¹,

Consoli²,

Gerich³

1992

J. Clin. Invest.

180

122

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The present studies were undertaken to determine whether Iipolysis was increased in non-insulin-dependent diabetes mellitus (NIDDM) and, if so, to assess the influence of increased glycerol availability on its conversion to glucose and its contribution to the increased gluconeogenesis found in this condition. For this purpose, we infused nine subjects with NIDDM and 16 age-, weight-matched nondiabetic volunteers with 12-3H1 glucose and IU-'4C1 glycerol and measured their rates of glucose and glycerol appearance in plasma and their rates of glycerol incorporation into plasma glucose. The rate of glycerol appearance, an index of lipolysis, was increased 1.5-fold in NIDDM subjects (2.85±0.16 vs. 1.62±0.08 gmol/kg per min, P < 0.001). Glycerol incorporation into plasma glucose was increased threefold in NIDDM subjects (1.13±1.10 vs.036±0.02 ,mol/kg per min, P < 0.01) and accounted for twice as much of hepatic glucose output (6.0±0.5 vs. 3.0±0.2%, P < 0.001). Moreover, the percent of glycerol turnover used for gluconeogenesis (77±6 vs. 44±2, P < 0.001) was increased in NIDDM subjects and, for a given plasma glycerol concentration, glycerol gluconeogenesis was increased more than twofold. The only experimental variable significantly correlated with the increased glycerol gluconeogenesis after taking glycerol availability into consideration was the plasma free fatty acid concentration (r = 0.80, P < 0.01). We, therefore, conclude that lipolysis is increased in NIDDM and, although more glycerol is thus available, increased activity of the intrahepatic pathway for conversion of glycerol into glucose, due at least in part to increased plasma free fatty acids, is the predominant mechanism responsible for enhanced glycerol gluconeogenesis. Finally, although gluconeogenesis from glycerol in NIDDM is comparable to that of alanine and about one-fourth that of lactate in terms of overall flux into glucose, glycerol is probably the most important gluconeogenic precursor in NIDDM in terms of adding new carbons to the glucose pool. (J. Clin. Invest. 1992. 89:169-175.)

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Turnover and precursor-product relationships of nonlipid metabolites.

Cited by 80 publications

References 0 publications

Effect of exercise training at different intensities on fat metabolism of obese men

Effect of exercise training at different intensities on fat metabolism of obese men

The low-affinity glucocorticoid receptor regulates feeding and lipid breakdown in the migratory Gambel's white-crowned sparrowZonotrichia leucophrys gambelii

Increased lipolysis and its consequences on gluconeogenesis in non-insulin-dependent diabetes mellitus.

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