Impact of Various Exercise Modalities on Hepatic Mitochondrial Function

• Published in: Medicine and science in sports and exercise Vol. 46; no. 6; pp. 1089 - 1097
• Main Authors: FLETCHER, JUSTIN A, MEERS, GRACE M, LINDEN, MELISSA A, KEARNEY, MONICA L, MORRIS, E MATTHEW, THYFAULT, JOHN P, RECTOR, R SCOTT
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD American College of Sports Medicine 01-06-2014; Lippincott Williams & Wilkins
• Subjects: Animals; Biological and medical sciences; Fasting; Fundamental and applied biological sciences. Psychology; Gluconeogenesis; Human physiology applied to population studies and life conditions. Human ecophysiology; Male; Medical sciences; Mitochondria, Liver - enzymology; Mitochondria, Liver - metabolism; Mitochondrial Proteins - metabolism; Motor Activity - physiology; Organelle Biogenesis; Oxidation-Reduction; Palmitates - metabolism; Physical Conditioning, Animal - methods; Physical Conditioning, Animal - physiology; Physical Endurance - physiology; Pyruvic Acid - metabolism; Random Allocation; Rats, Sprague-Dawley; RNA, Messenger - metabolism; Space life sciences; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Physical exercise; Liver function; Mitochondria; FATTY ACID OXIDATION; HEPATIC; Liver; Lipids; MITOCHONDRIAL FUNCTION; Oxidation; Fatty acids; EXERCISE
• ISSN: 0195-9131; 1530-0315
• DOI: 10.1249/MSS.0000000000000223

PURPOSEHepatic mitochondrial adaptations to exercise are largely unknown. In this study, we sought to determine the effects of various exercise modalities on measures of hepatic mitochondrial function and metabolism.
METHODSMale Sprague–Dawley rats were randomly assigned (n = 8–10 per group) into sedentary (SED), voluntary wheel running (VWR), VWR with food pulled during the dark cycle (VMR-OF), treadmill endurance exercise (TM-END; 30 m·min, 12% gradient, 60 min·d, 5 d·wk), or treadmill interval sprint training (TM-IST; 50 m·min, 12% gradient, 6 × 2.5 min bouts, 5 d·wk) groups for a 4-wk intervention.
RESULTSHepatic mitochondrial state 3 and maximal uncoupled respiration were significantly (P < 0.05) increased in all four exercise groups compared with SED animals. In addition, hepatic mitochondrial [1-C] pyruvate oxidation to CO2, an index of pyruvate dehydrogenase (PDH) activity, was significantly increased in VWR-OF, TM-END, and TM-IST rats (P < 0.05), whereas exercise-induced increases in [2-C] pyruvate oxidation and [1-C] palmitate oxidation to CO2 did not reach statistical significance. Hepatic mitochondrial sirtuin 3 protein content, which putatively increases activity of mitochondrial proteins, was elevated in the VWR, VWR-OF, and TM-END groups (P < 0.05). In addition, only VWR-OF animals experienced increases in hepatic cytochrome c protein content and phosphoenolpyruvate carboxykinase mRNA, whereas PGC-1α mRNA expression and phospho-CREB protein content was increased in VWR-OF and TM-END groups.
CONCLUSIONFour weeks of exercise training, regardless of exercise modality, significantly increased hepatic mitochondrial respiration and evoked other unique improvements in mitochondrial metabolism that do not appear to be dependent on increases in mitochondrial content.