The Effects of Exogenous Lactate Administration on the IGF1/Akt/mTOR Pathway in Rat Skeletal Muscle

Sunghwan Kyun, Choongsung Yoo, Hun-Young Park, Jisu Kim and Kiwon Lim
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Sunghwan Kyun: Department of Physical Education, Konkuk University, Gwangjin-gu, Seoul 05029, Korea
Choongsung Yoo: Department of Health and Kinesiology, Texas A&M University, College Station, TX 77843, USA
Hun-Young Park: Department of Sports Medicine and Science, Konkuk University, Gwangjin-gu, Seoul 05029, Korea
Jisu Kim: Department of Sports Medicine and Science, Konkuk University, Gwangjin-gu, Seoul 05029, Korea
Kiwon Lim: Department of Physical Education, Konkuk University, Gwangjin-gu, Seoul 05029, Korea

IJERPH, 2020, vol. 17, issue 21, 1-11

Abstract: We investigated the effects of oral lactate administration on protein synthesis and degradation factors in rats over 2 h after intake. Seven-week-old male Sprague–Dawley rats were randomly divided into four groups ( n = 8/group); their blood plasma levels of lactate, glucose, insulin, and insulin-like growth factor 1 (IGF1) were examined following sacrifice at 0, 30, 60, or 120 min after sodium lactate (2 g/kg) administration. We measured the mRNA expression levels of protein synthesis-related genes (IGF receptor, protein kinase B (Akt), mammalian target of rapamycin (mTOR)) or degradation-related genes (muscle RING-finger protein-1 (MuRF1), atrogin-1) and analyzed the protein expression and phosphorylation (activation) of Akt and mTOR. Post-administration, the plasma lactate concentration increased to 3.2 mmol/L after 60 min. Plasma glucose remained unchanged throughout, while insulin and IGF1 levels decreased after 30 min. The mRNA levels of IGF receptor and mTOR peaked after 60 min, and Akt expression was significantly upregulated from 30 to 120 min. However, MuRF1 and atrogin-1 expression levels were unaffected. Akt protein phosphorylation did not change significantly, whereas mTOR phosphorylation significantly increased after 30 min. Thus, lactate administration increased the mRNA and protein expression of protein-synthesis factors, suggesting that it can potentially promote skeletal muscle synthesis.

Keywords: exogenous lactate; protein synthesis; protein degradation; Akt; mTOR; IGF receptor (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2020
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