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

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.

Acute Administration of Exogenous Lactate Increases Carbohydrate Metabolism during Exercise in Mice

“…Interestingly, we have previously confirmed the potential of lactate as a supplement by examining the effects of lactate intake at rest on metabolism [ 23 , 24 ]. The main aim of the present study was to investigate the effect of lactate intake on metabolism during exercise.…”

“…Mice were randomly divided into the EX and EXLA groups ( n = 8 per group, average weight: EX group = 32.4 ± 0.84, EXLA group = 32.5 ± 1.28). Prior to conducting the experiment, all groups were fasted for 8 h. The EXLA group was administered 3 g/kg of sodium lactate with an oral sonde and the EX group an equal amount of a saline solution [ 23 , 41 ]. The mice were orally administered the appropriate supplement 30 min before a moderate intensity (about 60–70% VO 2max ) exercise was conducted for 30 min (treadmill exercise at a speed of 18 m/min and slope of 6°) [ 42 , 43 ].…”

“…Hoshino et al [ 22 ] reported that chronic post-exercise lactate administration increased the levels of monocarboxylate transporter 1 (MCT1) and improved skeletal muscle glycogen recovery and storage capacity. Moreover, Kyun et al [ 23 ] reported that exogenous lactate administration increased the mRNA and protein levels of protein-synthesis-related factors in the skeletal muscle, suggesting the potential of lactate as a supplement that promotes muscle synthesis. In addition, at rest, exogenous lactate intake increased glycogen synthesis- and fat metabolism-related factors [ 24 ].…”

Exosomal miR-486-5p derived from human placental microvascular endothelial cells regulates proliferation and invasion of trophoblasts via targeting IGF1

“…## P < 0.01 compared to H/R-exo. ^^P < 0.01 compared to (H/R + NC inhibitor)-exo in some diseases [30][31][32]. Previous research found that IGF1 overexpression may promote the migration of trophoblast cells [24].…”

Knockdown of FAM225B inhibits the progression of the hypertrophic scar following glaucoma surgery by inhibiting autophagy

“…This process is necessary for maintaining the cellular functions, which in turn protect the organisms against inflammatory injuries ( 21 , 22 ). Recent reports have revealed that autophagy can inhibit the formation of HSs ( 23 – 25 ). These findings indicated that autophagy serves a crucial role during the formation of HS; however, the relationship between FAM225B and cell autophagy is yet to be elucidated.…”