A comparison of the effects of ursolic acid and L-leucine supplementation on markers of muscle protein synthesis via Akt-mTOR signaling response to resistance exercise.

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dc.contributor.advisorWilloughby, Darryn Scott, 1963-
dc.contributor.authorChurch, David D.
dc.contributor.departmentHealth, Human Performance and Recreation.en_US
dc.contributor.schoolsBaylor University. Dept. of Health, Human Performance and Recreation.en_US
dc.date.accessioned2014-09-05T13:29:52Z
dc.date.available2014-09-05T13:29:52Z
dc.date.copyright2014-08
dc.date.issued2014-09-05
dc.description.abstractResistance exercise (RE) stimulates skeletal muscle protein synthesis (MPS) during post-exercise recovery due to up-regulation 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-1R^Tyr1131). Furthermore, the purpose was to also determine the effects on signaling intermediates of MPS contained within the Akt/mTOR pathway (phosphorylated levels of Akt^Thr308, mTOR^Ser2448, p70S6K^Thr389). In a randomized, cross-over design, nine apparently healthy, resistance-trained [regular, consistent resistance training (i.e. thrice weekly) for at least 1 year prior to the onset of the study], men between the ages of 18-30 performed three separate testing sessions of lower-body resistance exercise involving 4 sets of 8-10 repetitions at 75-80% 1-RM on the angled leg press and knee extension exercises. Immediately after each resistance exercise session, participants orally ingested 3 grams (0.043 g/kg equivalent) of cellulose placebo (PLC), L-leucine (LEU), or ursolic acid (UA). A venous blood sample was obtained before, and 0.5, 2, and 6 hr post-exercise, whereas a vastus lateralis muscle biopsy was obtained before and 2 and 6 hr post-exercise. Each testing session was separated by 7 days to allow full recovery between sessions. Statistical analyses were performed utilizing separate two-way ANOVA for each criterion variable employing a probability level of ≤ 0.05. Using ELISA, no significant differences were observed among the three supplements for serum IGF-1 (p> 0.05). Also using ELISA, for skeletal muscle phosphoproteins, no significant differences existed among the three supplements for phosphorylated IGF-1R, Akt, and p70S6K (p> 0.05). However, the LEU supplement significantly increased phosphorylated mTOR compared to UA and PLC (p= 0.001). At the 3 g dose provided, ursolic acid was unable to increase IGF-1R signaling and, unlike L-leucine, ursolic acid had no positive effect on mTOR signaling activity. Therefore, ursolic acid appears to have no effect on mTOR activity when ingested immediately following resistance exercise.en_US
dc.description.degreeM.S.Ed.en_US
dc.identifier.urihttp://hdl.handle.net/2104/9152
dc.language.isoen_USen_US
dc.rightsBaylor University theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. Contact librarywebmaster@baylor.edu for inquiries about permission.en_US
dc.rights.accessrightsWorldwide access.en_US
dc.rights.accessrightsAccess changed 1/27/17.
dc.subjectMuscle protein synthesis.en_US
dc.subjectmTOR signalling pathway.en_US
dc.subjectResistance training.en_US
dc.subjectUrsolic acid.en_US
dc.subjectLeucine.en_US
dc.titleA comparison of the effects of ursolic acid and L-leucine supplementation on markers of muscle protein synthesis via Akt-mTOR signaling response to resistance exercise.en_US
dc.typeThesisen_US

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