Combined effect of exogenous insulin and sucrose on alterations in plasma lipoproteins induced by cholesterol feeding in the rat.
We have recently reported increased cholesterol concentrations in high-density and very-low-density lipoproteins (HDL and VLDL) in sucrose-fed rats with exogenous hyperinsulinemia. In order to see if exogenous hyperinsulinemia has any effect on the alterations in plasma lipoproteins induced by cholesterol feeding, we fed a cholesterol-rich diet supplemented with lard, cholic acid and propylthiouracil to hyperinsulinemic, sucrose-supplemented rats and examined plasma lipoprotein profiles. Three control groups were investigated: one receiving chow only, the other receiving a cholesterol-rich diet, the third receiving exogenous insulin, sucrose, and no cholesterol-rich diet but chow. Hyperinsulinemia was induced by a constant s.c. infusion of porcine insulin (6 U/day) from an osmotic minipump. Insulin infusion plus sucrose produced an increase in HDL cholesterol concentrations similar to that seen in the previously reported injection model in the face of no change in total and low-density lipoprotein (LDL) cholesterol. Rats receiving a cholesterol-rich diet but no insulin developed marked hypercholesterolemia characterized by an elevation of cholesterol not only in LDL but also in intermediate-density lipoprotein (IDL) and VLDL. Infusing insulin into cholesterol-fed rats produced a further increase in IDL and VLDL cholesterol but was not accompanied by any further increase in LDL cholesterol. HDL cholesterol was decreased below normal.
Kazumi
T
T
Department of Medicine, Hyogo Medical Center for Adults, Akashi, Japan.
Yoshino
G
G
Kasama
T
T
Iwatani
I
I
Tanaka
T
T
Baba
S
S
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002791:Cholesterol, Dietary / Q000494:pharmacology*; D002149:Energy Intake; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D008074:Lipoproteins / Q000097:blood*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D013395:Sucrose / Q000494:pharmacology*; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D002791:Cholesterol, Dietary; D007328:Insulin; D008074:Lipoproteins; D014280:Triglycerides; D013395:Sucrose