Short communication: Leucine, but not muscle contractions, stimulates protein synthesis in isolated EDL muscles from golden geckos

TY - JOUR

T1 - Short communication

T2 - Leucine, but not muscle contractions, stimulates protein synthesis in isolated EDL muscles from golden geckos

AU - Rindom, Emil

AU - Ahrenfeldt, Mikkel

AU - Damgaard, Jeppe

AU - Overgaard, Kristian

AU - Wang, Tobias

N1 - Publisher Copyright: © 2022

PY - 2022/6

Y1 - 2022/6

N2 - Resistance exercise and protein ingestion stimulate muscle protein synthesis in mammals and the combination of both stimuli exert an additive effect. However, mechanisms regulating muscle mass may be different in ectothermic vertebrates because these animals are adapted to low energy consumption, short bouts of physical activity, and prolonged periods of inactivity. Here, we investigated the effects of administration of leucine and simulated resistance exercise induced by electrical stimulation (ES) on protein synthesis rate in isolated extensor digitorum longus muscle from golden geckos (Gekko badenii). Muscles were placed in Krebs-Ringer buffer equilibrated with O2 (97%) and CO2 (3%) at 30 °C. One muscle from each animal was subjected to one of three interventions: 1) administration of leucine (0.5 mM) at rest, 2) isometric contractions evoked by ES, or 3) a combination of contractions and leucine, while the contralateral muscle served as untreated control. The rate of protein synthesis was measured through pyromycin-labeling. Administration of leucine led to a 2.75 (±1.88)-fold rise in protein synthesis rate in inactive muscles, whereas isometric contractions had no effect (0.67 ± 0.37-fold). The combination of isometric contractions and leucine did not affect protein synthesis rate (1.02 ± 0.34-fold), suggesting that muscle contractions attenuated the positive influence of leucine. Our study identifies leucine as a potent positive regulator of muscle protein synthesis in golden geckos, but also demonstrates that muscle contraction is not. More studies should be conducted in other taxonomic groups of ectothermic vertebrates to identify whether this is a general pattern.

AB - Resistance exercise and protein ingestion stimulate muscle protein synthesis in mammals and the combination of both stimuli exert an additive effect. However, mechanisms regulating muscle mass may be different in ectothermic vertebrates because these animals are adapted to low energy consumption, short bouts of physical activity, and prolonged periods of inactivity. Here, we investigated the effects of administration of leucine and simulated resistance exercise induced by electrical stimulation (ES) on protein synthesis rate in isolated extensor digitorum longus muscle from golden geckos (Gekko badenii). Muscles were placed in Krebs-Ringer buffer equilibrated with O2 (97%) and CO2 (3%) at 30 °C. One muscle from each animal was subjected to one of three interventions: 1) administration of leucine (0.5 mM) at rest, 2) isometric contractions evoked by ES, or 3) a combination of contractions and leucine, while the contralateral muscle served as untreated control. The rate of protein synthesis was measured through pyromycin-labeling. Administration of leucine led to a 2.75 (±1.88)-fold rise in protein synthesis rate in inactive muscles, whereas isometric contractions had no effect (0.67 ± 0.37-fold). The combination of isometric contractions and leucine did not affect protein synthesis rate (1.02 ± 0.34-fold), suggesting that muscle contractions attenuated the positive influence of leucine. Our study identifies leucine as a potent positive regulator of muscle protein synthesis in golden geckos, but also demonstrates that muscle contraction is not. More studies should be conducted in other taxonomic groups of ectothermic vertebrates to identify whether this is a general pattern.

KW - Ectotherm

KW - Isometric contraction

KW - Nutrient availability

KW - Protein metabolism

KW - Resistance exercise

KW - Skeletal muscle

U2 - 10.1016/j.cbpa.2022.111206

DO - 10.1016/j.cbpa.2022.111206

M3 - Journal article

C2 - 35351650

AN - SCOPUS:85127582803

SN - 1095-6433

VL - 268

JO - Comparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology

JF - Comparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology

M1 - 111206

ER -