Our study investigates short- and long-term effects of infusion of non-esterified fatty acids (NEFA) on insulin secretion in healthy subjects. Twelve healthy individuals underwent a 24-h Intralipid (10% triglyceride emulsion) infusion at a rate of 0.4 ml/min with a simultaneous infusion of heparin (a bolus of 200 U followed by 0.2 U/min per kg body weight). After an overnight fast (baseline), at 6 and at 24 h of Intralipid infusion and 24 h after Intralipid discontinuation (recovery test), all subjects underwent an intravenous glucose tolerance test (iv-GTT) (25 g of glucose/min). Intralipid infusion caused a threefold rise in plasma NEFA concentrations with no difference between the 6- and the 24-h concentrations. Compared to baseline acute insulin response (AIR) (AIR = 63 +/- 8 mU/l), short-term (6-h) Intralipid infusion was associated with a significant increase in AIR (86 +/- 12 mU/l p < 0.01); in contrast, long-term (24-h) Intralipid delivery was associated with inhibition of AIR (31 +/- 5 mU/l) compared to baseline (p < 0.001) and to the 6-h (p < 0.03) triglyceride emulsion infusion. Intralipid infusion was associated with a progressive and significant decline in respiratory quotient (RQ). A positive correlation between changes in fasting plasma NEFA concentrations and AIR at the 6-h infusion (r = 0.89 p < 0.001) was found. In contrast, at the end of the Intralipid infusion period, changes in plasma NEFA concentrations and AIR were negatively correlated (r = -0.87 p < 0.001). The recovery test showed that fasting plasma NEFA concentrations, RQ and AIR had returned to baseline values. In the control study (n = 8) 0.9% NaCl infusion did not mimick the effect of Intralipid. In conclusion, our study demonstrates that short- and long-term exposures of beta cells to high plasma NEFA concentrations have opposite effects on glucose-induced insulin secretion.
This study demonstrated that GIT is lower in cancer patients than in healthy subjects matched with regard to age and body mass index. An overactivity of the glucose fatty acid cycle is responsible for such results. Plasma concentrations of TNF-alpha might play a modulating role in the metabolic changes that occur after administration of a glucose load. The role of TNF-alpha on glucose and lipid metabolism in cancer patients would be a worthy subject of future investigations.
load. Furthermore, the role of tumor necrosis factor-a (TNF-a) on cancer-induced metabolic changes is still a neglected area. Michele Varricchio, M.D. METHODS. In 25 cancer patients and 16 healthy subjects matched with regard to Department of Geriatric Medicine and Metabolic age, body mass index, and fat-free mass, indirect calorimetry was made before Diseases, II University of Naples, Naples, Italy. and after administration of a glucose load (75 g per subject, administered orally). RESULTS. Cancer patients had fasting plasma concentrations of insulin (74 { 3.3 vs. 67 { 4.1 pmol/L; P õ 0.05), lactate (0.68 { 0.11 vs. 0.41 { 0.1 mmol/L; P õ 0.05), free fatty acids (884 { 121 vs. 342 { 76 mmol/mL; P õ 0.001), and TNF-a (1.23 { 0.31 vs. 0.45 { 0.11 ng/mL; P õ 0.01) greater than controls, whereas plasma glucose concentrations (4.8 { 0.5 vs. 5.1 { 0.3 mmol/L; P Å not significant) were not different from controls. Indirect calorimetry at baseline demonstrated that basal metabolic rate, fat oxidation, and protein oxidation were significantly greater in cancer patients than in controls. After administration of the glucose load, carbohydrate oxidation progressively rose in both cancer patients and controls, with no differences between the two groups, whereas glucose uptake (59.3 { 3.8 vs. 69.1 { 3.6 g/kg fat-free mass [FFM] 1 240 minutes; P õ 0.01) and storage (49.1 { 4.1 vs. 60.2 { 3.3 g/kg FFM 1 240 minutes; P õ 0.05) were markedly reduced in cancer patients as compared with controls. Finally, glucose-induced thermogenesis (GIT) was lower in cancer patients than in controls. CONCLUSIONS. This study demonstrated that GIT is lower in cancer patients than in healthy subjects matched with regard to age and body mass index. An overacti-vity of the glucose fatty acid cycle is responsible for such results. Plasma concentrations of TNF-a might play a modulating role in the metabolic changes that occur after administration of a glucose load. The role of TNF-a on glucose and lipid metabolism in cancer patients would be a worthy subject of future investigations. high carbohydrate diet is frequently used to avoid weight loss in cancer patients; nevertheless, whether glucose administration has Diseases, Servizio di Astanteria Medica, Piazza a positive or adverse effect on energy expenditure and substrate oxida-Miraglia 2, I-80138 Naples, Italy. tion is still poorly understood. In fact, glucose administration has been shown to enhance energy expenditure and to stimulate insulin
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.