EFFECT OF DIET PROTEIN-CONCENTRATION ON P LASMA-GLUCOSE, INSULIN, GH AND AMINO-ACIDS LEVELS IN RATS

The effect of dietary protein content on the variations in plasma insu lin, GH, glucose and both gluconeogenic and branched-chain amino acids (BCAA) levels, was studied in Wistar rats. For 21 days animals consum ed ad libitum diets containing 4% (LP group) 10% (MP group) or 20% (HP group) protein. Body weight gain and plasma concentrations of the glu cose, insulin and both the insulin/glucose (I/G) and insulin/GH (I/GH) ratios varied directly with the protein content of the diet. In contr ast the relationships between dietary protein content and GH levels, w ere inverse. These results indicate that an increase of energy yieldin g nutrients availability and an decrease of tissue sensitivity to insu lin was produced as the protein content of the diet was increased. The increase of plasma aspartate, serine, histidine and alanine levels on LP group suggest a low gluconeogenic process, and the higher rate of BCAA on HP group against to MP and LP groups can be related to a lower tissue uptake. Both effects can be mediated by the tisular sensitivit y to insulin.