Insulin-like Growth Factor and Apolipoprotein B

Abstract

<h3>To the Editor.</h3> —Apolipoprotein B (apo B) is the principal protein component of the atherogenic lipoproteins low-density (LDL) and very-low-density (VLDL). The factors that regulate plasma apo B levels are of particular interest since in some data apo B is more closely related to coronary heart disease than LDL or VLDL cholesterol.¹We wondered whether insulin-like growth factor I (IGF-I) might be such a factor since the infusion of recombinant IGF-I recently was reported to lower plasma cholesterol levels.^2-4Indeed, previous work had shown that IGF-I deficiency states were accompanied by hypercholesterolemia.^5-7Our hypothesis was that apo B—containing lipoproteins were inversely related to circulating IGF-I in normal subjects. Insulin-like growth factor I,⁸insulin-like growth factor II (IGF-II),⁹and apo B¹⁰were measured in serum frozen at —70° obtained from 148 well-characterized, healthy men and women between the ages of 60 and 70 years for