Effect of Porcine Whole Blood Protein Hydrolysate on Slow-Twitch Muscle Fiber Expression and Mitochondrial Biogenesis via the AMPK/SIRT1 Pathway

Abstract

Skeletal muscle is a heterogeneous tissue composed of a variety of functionally different fiber types. Slow-twitch type I muscle fibers are rich with mitochondria, and mitochondrial biogenesis promotes a shift towards more slow fibers. Leucine, a branched-chain amino acid (BCAA), regulates slow-twitch muscle fiber expression and mitochondrial function. The BCAA content is increased in porcine whole-blood protein hydrolysates (PWBPH) but the effect of PWBPH on muscle fiber type conversion is unknown. Supplementation with PWBPH (250 and 500 mg/kg for 5 weeks) increased time to exhaustion in the forced swimming test and the mass of the quadriceps femoris muscle but decreased the levels of blood markers of exercise-induced fatigue. PWBPH also promoted fast-twitch to slow-twitch muscle fiber conversion, elevated the levels of mitochondrial biogenesis markers (SIRT1, p-AMPK, PGC-1α, NRF1 and TFAM) and increased succinate dehydrogenase and malate dehydrogenase activities in ICR mice. Similarly, PWBPH induced markers of slow-twitch muscle fibers and mitochondrial biogenesis in C2C12 myotubes. Moreover, AMPK and SIRT1 inhibition blocked the PWBPH-induced muscle fiber type conversion in C2C12 myotubes. These results indicate that PWBPH enhances exercise performance by promoting slow-twitch muscle fiber expression and mitochondrial function via the AMPK/SIRT1 signaling pathway.

Effect of Yeast-Derived Peptides on Skeletal Muscle Function and Exercise-Induced Fatigue in C2C12 Myotube Cells and ICR Mice

“…AMPK is considered as a key factor to regulate energy metabolism in cells. 10 Sirtuin 1 (Sirt1) and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) are the downstream molecules of AMPK. 11 PGC-1α, a transcription coactivator expressed in muscle, regulates mitochondrial biogenesis, 12 energy metabolism, and transformation of muscle fiber types.…”

Branched‐Chain Amino Acids and Mitochondrial Biogenesis: An Overview and Mechanistic Summary

“…As discussed in detail below, treatment with leucine has been repeatedly shown to increase markers of both mitochondrial biogenic signaling [ 22 , 27 , 28 , 29 , 31 , 32 , 34 , 35 , 38 , 51 , 54 , 58 , 59 , 60 ] and/or function [ 27 , 28 , 29 , 31 , 32 , 34 , 35 , 38 , 51 , 59 , 60 ] in 3T3‐L1 adipocytes, [ 29 ] C2C12 myocytes, [ 29 , 51 ] C2C12 myotubes, [ 27 , 28 , 32 , 34 , 35 , 38 , 60 ] porcine skeletal muscle satellite cells, [ 31 , 54 ] and mouse primary myocytes. [ 59 ] These findings suggest leucine, in particular, has the ability to stimulate signaling or outcomes associated with increased mitochondrial content and/or function.…”

“…[ 54 ] Leucine treatment for 3 days at low levels (50 µM) has also been shown to increase molecular regulators of mitochondrial biogenesis including pAMPK, PGC‐1α, NRF1, TFAM, and SIRT1 expression in C2C12 myotubes. [ 58 ] And although not in skeletal muscle, 160 µM leucine treatment for 2 h increased mitochondrial size and fusion in primary mouse and rat cardiomyocytes. [ 64 ]…”

“…In addition to in vitro data supporting a role for BCAA in mitochondrial biogenic signaling, several reports have also investigated the effects of individual or combination BCAA treatments on mitochondrial biogenesis and function in vivo. While valine and isoleucine are currently under‐investigated, leucine treatment has repeatedly resulted in increased mitochondrial biogenic signaling [ 22 , 30 , 31 , 58 , 68 , 69 , 70 , 71 , 72 , 73 ] and/or function [ 68 , 72 ] in several experimental models, such as male B6.Cg‐Ay/J mouse soleus, [ 68 ] aged C57BL/6J mouse quadriceps, [ 69 ] septic C57BL/6J mouse gastrocnemius, [ 70 ] ICR mouse quadriceps femoris, [ 58 ] C57BL/6J mouse WAT, [ 71 ] male Wistar rat soleus, [ 22 ] male Wistar rat EDL, [ 22 ] piglet Longissimus dorsi , [ 31 , 72 ] piglet liver, [ 30 ] and NW and growth‐slowed piglet liver. [ 73 ] For example, 1.5% leucine in drinking water for 4 months has been shown to increase expression levels of Ppara , Ucp3 , and Nrf1 in soleus muscle of Ay mice, as well as increase total energy expenditure (VO 2 ).…”

“…[ 70 ] And similar to their findings in an in vitro model of muscle, Institute of Cancer Research (ICR) mice supplemented with leucine at 500 mg kg −1 day −1 showed increased expression of mitochondrial biogenic‐related targets (pAMPK, PGC‐1α, NRF1, and TFAM expression, with unchanged SIRT1 expression) in quadriceps femoris muscle. [ 58 ] Leucine supplementation at 135 mg kg −1 BW for 1–3 h also increased mitochondrial biogenic signaling in male Wistar rats, evidenced by increased expression of Ppargc1a , Tfam , Atp5o , and Cycs in EDL, and increased Ppargc1a in soleus, which were harvested 3 h post gavage. [ 22 ] Conversely, tumor‐bearing Wistar rats given a 3% leucine‐supplemented diet for 18 days displayed unaltered tibialis anterior Cs expression but elevated Cox5a expression.…”