Diabetes, Vol 40, Issue 12 1669-1674, Copyright © 1991 by American Diabetes Association
Pioglitazone hydrochloride inhibits cholesterol absorption and lowers plasma cholesterol concentrations in cholesterol-fed rats
JR Colca, CF Dailey, BJ Palazuk, RM Hillman, DM Dinh, GW Melchior and CH Spilman
Upjohn Company, Kalamazoo, Michigan 49001.
Diabetes is associated with altered cholesterol metabolism that may
contribute to cardiovascular complications. Treatment of rats with
pioglitazone hydrochloride, a novel antidiabetic compound that improves the
general response of target cells to insulin, significantly lowered
cholesterol levels in rats fed a hypercholesterolemic diet and produced a
significant reduction in cholesterol absorption. Drug treatment was
ineffective in rats that were not given dietary cholesterol. To determine
whether these effects of pioglitazone hydrochloride might be related to the
known ability of this compound to improve the response to circulating
insulin, similar studies were conducted in streptozocin-induced diabetic
rats with and without insulin replacement. Diabetic rats absorbed a greater
percentage of dietary cholesterol than control rats. Treatment of
insulin-deficient diabetic rats with pioglitazone alone did not affect
cholesterol absorption; however, the combination of insulin and
pioglitazone was synergistic to lower absorption of cholesterol and
circulating cholesterol and triglycerides. Treatment of either normal rats
or diabetic rats receiving insulin with pioglitazone hydrochloride produced
a twofold decrease in the ratio of total cholesterol to high-density
lipoprotein cholesterol. These results suggest that treatments that improve
insulin sensitivity may also have a positive impact on coronary artery
disease associated with diabetes.