Metabolic Support Effects of Growth Hormone and Insulin-Like Growth Factor 1 (IGF-1) Treatments on the Nitrogen Metabolism and Hepatic IGF-1-Messenger RNA Expression in Postoperative Parenterally Fed Rats

ABSTRACT. Background: Few studies have made direct compari-sons of the metabolic effects of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). We have assessed the dose-dependent effects of GH and IGF-1 treatments on nitrogen metabolism, intes-tinal structure, and hepatic IGF-1-messenger RNA (mRNA) expres-sion in postoperative parenterally fed rats. Methods: Rats were maintained on total parenteral nutrition (TPN) for 3 days after gastrectomy. GH (0.4 or 0.8 IU/kg/d) or IGF-1 (1, 2, or 4 mg/kg/d) was infused throughout the experimental period. Anabolic effects of GH and IGF-1 were assessed by body weight change, nitrogen excretion, and whole-body protein turnover. Organ weights, intes-tinal structure, plasma IGF-1 levels and hepatic IGF-1-mRNA con-tents were also determined. Results: Both GH and IGF-1 attenuated body weight loss and nitrogen excretion and increased whole-body protein synthesis and spleen weight. These observations suggest that the anabolic effects of 1 mg/kg/d of IGF-1 were equivalent to those of 0.66 IU/kg/d of GH. IGF-1, but not GH, reduced atrophy of the intestinal mucosa. GH treatment increased hepatic IGF-1-mRN