Does Insulin and Leucine Stimulate Muscle Protein Synthesis?
University of Nebraska 2005 Swine Day Report. Improvement of protein synthesis in muscle will greatly enhance the production of lean pork. This improvement can be traced to changes at the cellular level. The object of this study was to identify the effects of insulin and the branched chain amino acid, leucine on the extent and rate that messenger RNA (mRNA) is translated into protein. Porcine satellite cells were isolated from a 30 lb pig and cultured. The cultured cells were treated with varying levels of insulin and leucine. Increasing levels of insulin and leucine caused an increase in ribosomes, the organelles responsible for synthesis, only after leucine was present in the media in adequate concentrations. With increasing levels of insulin there was an increase in the recruitment of ribosomes into polyribosomes for mRNA translation. However, increasing leucine levels had no effect on polyribosome percentage. In conclusion, insulin stimulates translation of mRNA by increasing both ability and rate. However, adequate levels of amino acid must be available for the stimulation to occur. Increased levels of branched chain amino acid do not create a synergistic effect with insulin to increase polyribosomes for protein synthesis.