Insulin-like growth factor-I fails to reverse corticosteroid-induced protein catabolism in growing piglets

Corticosteroids such as dexamethasone (DEX) increase leucine turnover and oxidation in humans and animals, indicating whole body protein catabolism. Recently, interest has been growing in the use of recombinant polypeptides such as GH and IGF-I in reversing various states of catabolism. The aim of our study was to investigate whether IGF-I reverses corticosteroid-induced protein catabolism in rapidly growing piglets. Also, we wanted to determine whether IGF-I attenuates corticosteroid-induced hyperglycemia. To study these question, we performed leucine kinetics studies and measured blood glucose in eight piglets under postabsorptive conditions. We did three studies in each piglet: baseline, DEX treatment (5 mg/kg/d for 4 d), and DEX plus IGF-I treatment (25 mu g/kg/h for 6 h). DEX increased leucine turnover by 18 +/- 14% (mean +/- SD, p