Abstract
Polyamines; putrescine and spermine are important nutrients that support cell proliferation, and growth. Study of the influence of polyamines in skeletal muscle growth is limited. This research is driven towards understanding nutritional means for optimizing muscle growth in cattle. Using commercial cell lines; c2c12 and sol8 cells the effects of physiological doses of polyamines in undifferentiated and differentiated cells was assessed in the context of mRNA analyses of key myogenic transcription factors and the mRNA for the rate limiting step for de novo synthesis of polyamines; ornithine decarboxylase. Myogenic transcription factors (MyoD, Myf5, myogenin) and ODC mRNA were measured at 8 and 16 hr. time points after treatment with polyamines, or methionine (aa control) or no polyamine supplementation (control). Exogenous supplementation with putrescine (5mM) or spermine (0.5mM) in undifferentiated c2c12 and sol8 cells significantly increases in myogenic transcription factors and ODC mRNA. However, polyamine treatment of differentiated c2c12 and sol8 cells resulted in a significant decrease in myogenic transcription factors and ODC mRNA at similar time points. Methionine (10mM) treatment of undifferentiated c2c12 and sol8 cells did not show a significant difference in their myogenic transcription factor mRNA relative to control, however ODC mRNA increases. Treatment of differentiated c2c12 and sol8 cells with the amino acid control; methionine (10mM), resulted in a similar pattern of mRNA abundance as was observed for polyamine treated differentiated cells. These results indicate that polyamines may induce a promyogenic state in undifferentiated myoblasts (c2c12 and sol8) at 8hr and 16hr as compared to controls, though the evaluation of more time points as well as further study in differentiated myoblasts is critical for a clearer understanding of the role of polyamines in skeletal muscle growth.