Christophe Noll1, Frédérique Frisch, Lucie Bouffard, Serge Phoenix, Stephen C. Cunnane, Brigitte Guérin, Eric E. Turcotte, François-Charles Malo, André C. Carpentier1.
1Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Québec.
Christophe.Noll@USherbrooke.ca
Background: Obesity is expected to reach one-third of the Canadian population by 2030. Bariatric surgery offers sustainable weight loss along with improvements in quality of life and metabolic health. The aim of our study is to observe the early effects of sleeve gastrectomy on postprandial hepatic and cardiac dietary fatty acids (DFA) and non-esterified fatty acids (NEFA) metabolism.
Methods: Subjects followed protocols before and 10-14 days after surgery. After a 12-hour fast, participants underwent hepatic MRI to determine steatosis. Then, patients received an injection of [11C]-palmitate, a NEFA metabolism tracer, to assess hepatic and cardiac metabolism via positron emission tomography (PET) imaging. Finally, a liquid meal was ingested with a PET tracer, a long-chain fatty acid analog, [18F]-FTHA, to determine the distribution of DFA within organs over a 6-hour period post-meal.
Results: Eight subjects (4M/4W) have completed the protocols. Participants lost approximately 8% of their body mass (137.8±12.7 vs. 126.9±12.0kg, P<0.008), 4% of their waist circumference (128.9±7.9 vs. 123.6±7.9cm, P<0.008) and nearly 38.5% of their intrahepatic fat fraction (n=6; 17.5±4.3 vs. 10.7±2.8%, P<0.04), but not total body fat mass (66.5±6.2 vs. 64.3±8.1kg, P=0.38). While hepatic DFA uptake did not change (4.2±0.3 vs. 4.0±0.3SUV [Standard Uptake Value], P=0.57), the liver did take up 29.5% more NEFA (289.8±56.7 vs. 375.3±41.4µmol.min⁻¹, P<0.03) with a significant increase in oxidative metabolism (136.4±43.9 vs. 206.8±38.1µmol.min⁻¹, P=0.05) after surgery. On the other hand, both cardiac DFA (2.4±0.1 vs. 1.7±0.2SUV, P<0.03) and NEFA uptake (165.7±24.1 vs. 125.6±16.0µmol.min-1, P=0.05) were nearly 25-30% less after surgery, with significant decrease in oxidative metabolism (154.7±25.0 vs. 55.7±14.6µmol.min-1, P<0.008).
Conclusion: Our preliminary results show heterogeneous responses between hepatic vs. cardiac fatty acid metabolism, with increase vs. reduction of fatty acid uptake and oxidation, respectively. The acceleration of hepatic fatty acid oxidation clearly plays a role in rapid reduction of liver fat content after sleeve gastrectomy.