RESUMO
The inclusion of 15% pectin in a diet causes growth retardation in rats, but the mechanism for the impaired growth has not been established. Serum concentration of IGF-I and proteoglycan synthesis rate on muscle and the tibial epiphysis, an estimate of biological response to IGF-I in a target tissue, were compared in weaning rat fed with 8.5% protein and levels of 7.5 and 15% of pectin and cellulose, respectively. In experiment 1 (G1-G6) was used cellulose as source of fiber and in experiment 2 (G7-G11) pectin. A marked reduction in weight, muscle and bone growth was observed for the groups fed on 15% pectin. Plasma IGF-I concentration correlated with both protein and tibial proteoglycan synthesis rate in the group with 15% pectin diet. However, in the group fed with cellulose the most of the parameters were well maintained, with exception the group fed with beans and rice (G5 e G6). Our study suggest that the inclusion of pectin in a experimental diet impairs growth by a combination of reduced food intake, a reduced anabolic response to food due to a reduced protein and proteoglycan synthesis possibly reflecting impaired IGF-I action and secretion.
