First Name:
Chelsea
Last Name:
Zemmin
Major Department:
Biology
Thesis Director:
Kevin Zwetsloot
Date of Thesis:
May 2014
Protein synthesis is a critical component in the normal physiology and maintenance of skeletal muscle. With aging there is a loss of muscle mass and a decrease in muscle protein synthesis. Phytoecdysteroids are natural plant steroids that possess medicinal and physiological properties. The phytoecdysteroid, 20-hydroxyecdysone (20E), stimulates protein synthesis in muscle cells in vitro and increases muscle fiber size in aged mice; however, further research is needed to determine the optimal time point for 20E-induced muscle protein synthesis. The purpose of this study was to examine the time course for the optimal activation of protein synthesis in skeletal muscle of young mice. Two doses of 20E were used in different time courses experiments: 50 and 200 mg/kg BW. Protein synthesis was assessed using the SUnSET technique, whereby mice were given an IP injection of puromycin prior to sacrifice and tissue harvest. The incorporation of puromycin was measured via Western and Dot Blots as an indicator of protein synthesis and the phosphorylation of Akt was measured via Western blot as an indicator of 20E-induced activation of the signaling pathway leading to protein synthesis. Results indicate that there was a significant increase in Akt phosphorylation at the 15-minute time point and tended to be an increase in puromycin incorporation at the 60-minute time point. These findings suggest that 20E stimulates the pathway for protein synthesis within 15 minutes, which results in higher levels of protein synthesis 45 minutes later. This information will aid in the design of future experiments investigating how 20E influences the mechanisms of protein synthesis in skeletal muscle.