Recombinant human insulin-like growth factor-I decreases serum lipoprotein(a) concentrations in normal adult men

Lipoprotein(a) is a lipoprotein fraction associated with atherosclerosis. The serum concentration of lipoprotein(a) has been shown to be mainly genetically determined but recently evidence for hormonal regulation has been presented. The aim of the present study was to investigate the effects of insulin-like growth factor-I on serum lipoproteins, especially lipoprotein(a).

The effects of one week of IGF-I treatment were studied in an open trial.

Ten healthy men, who participated in a pharmacokinetic study, were given recombinant human insulin-like growth factor-I (40 micrograms/kg/day) as daily subcutaneous injections.

Serum samples for measurements of lipoproteins were taken after an overnight fast before and after 7 days of treatment.

There was decrease in serum lipoprotein(a) concentration (18.5 +/- 5.5%) in nine of the subjects, and a slight increase in one of the subjects with the lowest concentrations. Also serum apolipoprotein (b) (6.3 +/- 2.2%), serum cholesterol (10.6 +/- 1.8%) and serum triglyceride (14.8 +/- 4.8%) concentrations decreased. An unexpected finding was that fasting serum glucose concentrations increased (13 +/- 4%).

Insulin-like growth factor-I is involved in the regulation of lipoprotein(a) concentrations, which might have novel therapeutic implications.