Single sc Administration of Insulin-Like Growth Factor I (IGF-I) in Normal Men

Insulin-like growth factor I (IGF-I) has been synthesized by recombinant DNA technology (1). With the availability of large quantities of the biosynthetic peptide, the biological effects have been studied in animals in vivo. We have previously reported that IGF-I has growth promoting, anabolic, and insulin-like effects in hypophysectomized and normal rats, and IGF-I inhibits catabolism in fasted rats in vivo (2–5). Recently, the biological effects of IGF-I have been studied in normal men and patients with Laron-type dwarfism (6–9). We have also studied effects of IGF-I single sc administration in normal men (10). In this paper, the results of the single sc administration of IGF-I combined with our previous data (10) are reported.