Insulin-like growth factor-I lowers fasting and postprandial triglyceride levels without affecting chylomicron clearance in healthy men

Objectives. To study whether IGF-I treatment alters the postprandial lipid and lipoprotein metabolism. Design. Randomized, crossover study, Setting. University Hospital, Zurich, Switzerland, Subjects. Seven young healthy male subjects (aged 27 +/- 4 years, body mass index (BMI) 21.8 +/- 1.7 kg m(-2)). Interventions. Each subject was studie d two times at 2-week intervals, treated with saline 0.9% (S) and IGF-I (8 mu g kg-l h-l) by a continuous subcutaneous infusion. 60 h after the start of treatment a vitamin A loading test was performed after an overnight 12-h fast, Main outcome measures. Glucose, insulin, total and free IGF-I, FFA, triglyc erides and retinyl palmitate, total cholesterol, HDL and LDL cholesterol, l ipoprotein (a) and apolipoprotein B were measured in serum before and after the fatty meal, Results. Total TGF-I levels rose from 29.0 +/- 3.3 nmol L-l to 113.3 +/- 9. 0 nmol L-1(P < 0.02) and free IGF-I from 0.24 +/- 0.05 to 1.08 +/- 0,28 nmo l L-1 (P < 0.02) during IGF-I treatment, ICE-I administration reduced insul in concentrations by 50% (P < 0.02), as assessed by the area under the curv e. Serum triglyceride levels were significantly lower at baseline and after the fat load during IGF-T treatment (P < 0.02), whereas the retinyl palmit ate concentrations in chylomicron and nonchylomicron lipoprotein fractions were similar during both treatment periods. Conclusions. ICE-I treatment reduces the triglyceride levels most probably by decreasing insulin secretion and the production of VLDL particles, and p ossibly by increasing their turnover. IGF-I treatment has no significant ef fect on the metabolism of intestine-derived triglyceride-rich lipoproteins after a high fat meal in healthy young men.