PRE- AND POSTNATAL PROTEIN UNDERNUTRITION INCREASES LIVER-GLYCOGEN CONCENTRATION AND THE ACTIVITY OF GLYCOGEN SYNTHASES IN THE SUCKLING RAT

We observed a significant increase in hepatic glycogen concentration f rom undernourished rats in comparison to a control group; the undernou rished group also showed a significant rise in glycogen synthases D an d R + I activities. The method used to determine the activities of gly cogen synthases maximises the activity of synthase R, which is the for m responsible for glycogen synthesis in vivo. We did not observe diffe rences between glycogen phosphorylases activity from undernourished an d control rats. There were no differences in hepatic glycogen concentr ation after a 20 h fast between the two groups. However, the hepatic g lycogen mobilisation, expressed as mg glycogen/g body weight was signi ficantly greater in the undernourished rats. These results show that a greater hepatic glycogen concentration found in undernourished rats i s not due to a deficient glycogen mobilisation. Instead, it may be the result of an increase in synthases R + I activity. Probably, at this phase of undernutrition, the rats present with an enhanced sensitivity to insulin.