Effects of insulin-like growth factor on weight gain in chronic hypoxic rats

Chronic hypoxemia has been suggested as the cause of weight loss in malnourished patients with chronic obstructive pulmonary disease. Insulin-like growth factor I (IGF-I) is believed to improve nitrogen balance and have anabolic effects, and it has been proposed as one of the mediators of vascular smooth muscle proliferation. The aim of this study was to assess the effects of IGF-I administration on the nutritional status and pulmonary vasculature in normoxic and chronic hypoxic rats. Twenty rats were randomly assigned to the normoxic (n = 10) and chronic hypoxic groups (n = 10). They received daily subcutaneous injections of either 3.2 mg/kg of recombinant human IGF-I (rhIGF-I) or isotonic saline (control group) for 3 weeks. Body weight was greater in IGF-I-treated rats compared with vehicle-treated rats, especially during the early and late stages of chronic hypoxic exposure, whereas similar weight gain was observed between IGF-I- and vehicle-treated normoxic rats. In addition, IGF-I treatment increased serum total protein and albumin at the end of hypoxic exposure. However, IGF-I had no additive effects on the degree of pulmonary hypertension. These results indicated that IGF-I promoted anabolism under chronic exposure to hypoxia, whereas no adverse effect was observed in the development of pulmonary hypertension.