Journal of Lipid Research, Vol 28, 10-18, Copyright © 1987 by Lipid Research, Inc.
Role of insulin in regulation of high density lipoprotein metabolism
A Golay, L Zech, MZ Shi, CY Jeng, YA Chiou, GM Reaven and YD Chen
The effect of alloxan-induced insulin deficiency on high density
lipoprotein (HDL) metabolism was studied in rabbits. Rabbits with
alloxan-induced diabetes had significantly higher (P less than 0.001, mean
+/- SEM) plasma concentrations of glucose (541 +/- 13 vs. 130 +/- 2 mg/dl),
triglyceride (2851 +/- 332 vs. 101 +/- 10 mg/dl), and total plasma
cholesterol (228 +/- 55 vs. 42 +/- 4 mg/dl) than did normal control
rabbits. However, diabetic rabbits had lower plasma HDL- cholesterol (7.2
+/- 1 vs. 51.3 +/- 1.3 mg/dl, P less than 0.001) and HDL apoA-I (38.3 +/-
6.0 vs. 87.2 +/- 4.3 mg/dl, P less than 0.001) concentrations. HDL kinetics
were compared in diabetic and normal rabbits, using either 125I-labeled HDL
or HDL labeled with 125I-labeled apoA-I, and it was demonstrated that HDL
fractional catabolic rate (FCR) was slower and residence time was longer in
the diabetic rabbits when either tracer was used. The slow FCR and the low
apoA-I pool size led to reduced apoA-I/HDL synthetic rate in diabetic
rabbits (0.97 +/- 0.11 vs. 0.34 +/- 0.07 mg per kg per hr). Thus, the
reduced plasma HDL- cholesterol concentrations seen in rabbits with
alloxan-induced insulin deficiency was associated with a lower total
apoA-I/HDL synthetic rate. Since insulin treatment restored to normal all
of the changes in plasma lipoprotein concentration and kinetics seen in
diabetic rabbits, it is unlikely that the phenomena observed were secondary
to a nonspecific toxic effect of alloxan. These data strongly support the
view that insulin plays an important role in regulation of HDL metabolism.