Effects of Continuous Infusion of 20-Hydroxyecdysone in C57BL/6 Mice

20-Hydroxyecdysone (20E) is the most abundant phytoecdysteroid produced by several plant families and has been attributed with numerous pharmacological properties in animals including anabolic and immune modulating effects. However, the in vivo bioactivity of phytoecdysteroids in mammals remains ambiguous, and moreover, the mechanism of action in mammals has yet to be determined. In this study, the physiological and gene expression effects of 20E were analyzed in C57BL/6 mice given a continuous infusion of saline or 20E (5 mg/kg/day) for five or fifteen days using subcutaneously implanted Alzet® osmotic pumps. The weights of the total body, muscle groups and organs were recorded and carcass composition was determined to evaluate changes in nutrient partitioning. There was a significant increase (p = 0.01) in the weight of triceps brachii in mice treated with 20E for five days (115 +/- 8 mg) compared to mice treated with saline for five days (88 +/- 3 mg), however, there were no differences in the other measured parameters. To determine potential mechanisms of action of 20E in skeletal muscle, Illumina’s Mouse Whole Genome-6 v2.0 Expression BeadChips were used to evaluate changes in gene expression after 20E infusion. False Discovery Rate correction of microarray data did not reveal any beadtypes that were differentially expressed. Therefore, Ingenuity Pathways Analysis (IPA) was used to identify genes with the most evidence for differential expression in the context of biological functions and pathways. IPA provided evidence for 20E involvement in processes including cellular growth and proliferation and cell-to-cell signaling and interaction. Overall, the data suggests that 20E does not have potent anabolic properties. IPA identified potential lead biological processes and pathways of 20E. Total RNA was extracted from the triceps brachii of C57BL/6 mice given a continuous infusion of saline or 20E (5 mg/kg/day) for 5 or 15 days using subcutaneously implanted Alzet® osmotic pumps to evaluate gene expression effects of 20E on mouse muscle.