Insulin-like growth factor-I lowers fasting and postprandial triglyceride levels without affecting chylomicron clearance in healthy men.
OBJECTIVE
To study whether IGF-I treatment alters the postprandial lipid and lipoprotein metabolism.


METHODS
Randomized, crossover study.


METHODS
University Hospital, Zürich, Switzerland.


METHODS
Seven young healthy male subjects (aged 27+/-4 years, body mass index (BMI) 21.8+/-1.7 kg m(-2)).


METHODS
Each subject was studied two times at 2-week intervals, treated with saline 0.9% (S) and IGF-I (8 microg kg(-1) h(-1)) 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.


METHODS
Glucose, insulin, total and free IGF-I, FFA, triglycerides and retinyl palmitate, total cholesterol, HDL and LDL cholesterol, lipoprotein (a) and apolipoprotein B were measured in serum before and after the fatty meal.


RESULTS
Total IGF-I levels rose from 29.0+/-3.3 nmol L(-1) 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 nmol L(-1) (P<0.02) during IGF-I treatment. IGF-I administration reduced insulin concentrations by 50% (P<0.02), as assessed by the area under the curve. Serum triglyceride levels were significantly lower at baseline and after the fat load during IGF-I treatment (P<0.02), whereas the retinyl palmitate concentrations in chylomicron and nonchylomicron lipoprotein fractions were similar during both treatment periods.


CONCLUSIONS
IGF-I treatment reduces the triglyceride levels most probably by decreasing insulin secretion and the production of VLDL particles, and possibly by increasing their turnover. IGF-I treatment has no significant effect on the metabolism of intestine-derived triglyceride-rich lipoproteins after a high fat meal in healthy young men.
Bianda
T
T
Department of Internal Medicine, University Hospital, Zürich, Switzerland. ndosam@usz.unich.ch
Zapf
J
J
Froesch
E R
ER
Schmid
C
C
D000328:Adult; D002153:Calorimetry, Indirect; D002914:Chylomicrons / Q000097:blood*; D018592:Cross-Over Studies; D004224:Diterpenes; D005215:Fasting / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008055:Lipids / Q000097:blood; D008297:Male; D019518:Postprandial Period; D012016:Reference Values; D000084562:Retinyl Esters; D014280:Triglycerides / Q000097:blood*; D014801:Vitamin A / Q000031:analogs & derivatives
D002914:Chylomicrons; D004224:Diterpenes; D007328:Insulin; D008055:Lipids; D000084562:Retinyl Esters; D014280:Triglycerides; D014801:Vitamin A; C014794:retinol palmitate; D007334:Insulin-Like Growth Factor I