Effect of protein deficiency on plasma insulin-like growth factor-I (IGF-I) level and protein and proteoglycan synthesis rates in skeletal muscle and bone
1996
Tirapegui, J. | Baldi, M. | Ribeiro, S.L.
Although protein deficiency in young children or young animals is frequently associated with growth retardation, the mechanism for impaired growth has not been established. In this article studies on rats investigate changes in plasma concentration of IGF4 in relation to the inhibition of bone and muscle growth are reported. This article also examines protein and proteoglycan synthesis through protein deficiency and recovery afterwards. A marked reduction in weight, food intake, muscle and bone growth was detected in the protein-deficient rats. The decrease of protein and proteoglycan synthesis in the tissues was also observed. The concentration of IGF-I plasma correlated with both protein and tibial proteoglycan synthesis rates and with the increase of protein content in the diet. However, in the 7.5% casein group these parameters were well maintained due to the increase of food intake. The recovered groups showed an increase in the protein and proteoglycan synthesis and this change correlated with the concentration of IGF-I. Thus protein deficiency impaired growth by a combination of reduced food intake and a reduced anabolic response to food due to a reduced protein and proteoglycan synthesis possibly reflecting impaired IGF-I secretion.
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