A comparison of the effects of ursolic acid and l-leucine supplementation on IGF-1 receptor and AKT-mTOR signaling in response to resistance exercise in trained men

David Church,Darryn S Willoughby,Neil Schwarz,Tom Andre,Mike Spillane,Sarah Mckinley

doi:10.1186/1550-2783-11-s1-p19

David Church, Darryn S Willoughby + Show 4 more

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https://doi.org/10.1186/1550-2783-11-s1-p19

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Abstract

Background Resistance exercise stimulates skeletal muscle protein synthesis (MPS) during post-exercise recovery due to upregulation of the mammalian target of rapamycin (mTOR) signaling pathway. L-leucine supplementation is also known to stimulate MPS by activating mTOR signaling. However, recent research has discovered a natural compound called ursolic acid which also appears to stimulate MPS by activating the mTOR signaling pathway, and has been presumed to occur due to IGF-1 receptor (IGF-1R) up-regulation. Ursolic acid is a natural pentacyclic triterpenoid carboxylic acid that is widely found in apple skin and other fruits such as cranberries. The main purpose of this study was to compare the effects of a single dose of ursolic acid or L-leucine supplementation given immediately after resistance exercise on IGF-1 (a serum regulator of MPS) and the subsequent effects of IGF-1 on phosphorylating/activating its receptor (IGF-1RTyr1131). Furthermore, the purpose was to also determine the effects on signaling intermediates of MPS contained within the Akt/ mTOR pathway (phosphorylated levels of AktThr308, mTORSer2448, p70S6KThr389).

Highlights

Resistance exercise stimulates skeletal muscle protein synthesis (MPS) during post-exercise recovery due to upregulation of the mammalian target of rapamycin signaling pathway
A comparison of the effects of ursolic acid and l-leucine supplementation on IGF-1 receptor and AKT-mammalian target of rapamycin (mTOR) signaling in response to resistance exercise in trained men
Using ELISA, for skeletal muscle phosphoproteins, no significant differences existed among the three supplements for phosphorylated IGF-1 receptor (IGF-1R), Akt, and p70S6K (p > 0.05)

Summary

Introduction

Resistance exercise stimulates skeletal muscle protein synthesis (MPS) during post-exercise recovery due to upregulation of the mammalian target of rapamycin (mTOR) signaling pathway. L-leucine supplementation is known to stimulate MPS by activating mTOR signaling. Recent research has discovered a natural compound called ursolic acid which appears to stimulate MPS by activating the mTOR signaling pathway, and has been presumed to occur due to IGF-1 receptor (IGF-1R) up-regulation. The main purpose of this study was to compare the effects of a single dose of ursolic acid or L-leucine supplementation given immediately after resistance exercise on IGF-1 (a serum regulator of MPS) and the subsequent effects of IGF-1 on phosphorylating/activating its receptor (IGF-1RTyr1131). The purpose was to determine the effects on signaling intermediates of MPS contained within the Akt/ mTOR pathway (phosphorylated levels of AktThr308, mTORSer2448, p70S6KThr389)

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