Effect of insulin in the induction and regression of experimental cholesterol atherosclerosis in the rabbit

A study was undertaken to determine the effects of long-term insulin therapy on the development and regression of lipid perturbations and experimental cholesterol atherosclerosis in rabbits: (1) Insulin administration for 15 days significantly reduced plasma lipid levels and free fatty acids in rabbits fed a high-cholesterol diet; it also inhibited the effects of a single dose of cholesterol. Paradoxically, continued insulin treatment led to the reinforcement of lipaemia through the stimulation of mobilization. Insulin administration during the development of atherosclerosis significantly aggravated the fatty infiltration of the aortic tissue and the lesions of the vessels, and also increased the frequency of coronary lesions. (2) In rabbits fed a cholesterol enriched diet during two months and then a normal diet, insulin treatment accelerated the rate of reduction of hypercholesterolaemia, but aggravated the lipid infiltration of the artery walls, and also prevented regression of coronary atherosclerosis.