Comparison of clofibrate and ethyl-5-(p-chlorophenoxy)-3-hydroxy-3-methylpentanoate induced changes in serum lipoprotein cholesterol and hepatic peroxisome proliferation in the normal rat.
Clofibrate and ethyl-5(p-chlorophenoxy)-3-hydroxy-3-methylpentanoate (HMP), at 0.1 and 0.25% in the diet, were evaluated in normal rats. Effects on serum lipoprotein cholesterol, liver cholesterol and peroxisome proliferation changes were compared. Both doses of HMP significantly lowered high density lipoprotein cholesterol (HDL-C) and total cholesterol (mean 22% and 18%). The distribution of cholesterol in the lipoproteins was altered (p less than 0.05) and liver weights were increased 18% by the 0.25 dose of HMP. Clofibrate treatment increased (p less than 0.01) the combination of very low and low density lipoprotein cholesterol (VLDL + LDL-C) by 42% at the 0.1% dose and lowered HDL-C by 28% at the 0.25% dose; total-C was not changed from control values. Both levels of clofibrate shifted the distribution of lipoprotein cholesterol, increased liver weights (mean 69%) and reduced liver cholesterol (mean 33%). Image analysis of peroxisome changes showed that both doses of HMP and clofibrate increased peroxisome numbers (mean 71% vs 218%), with activity of HMP significantly lower than clofibrate. Measurement of carnitine acetyltransferase (CAT) activity (nmCoASH released/mg protein/minute) showed no significant increases in liver samples from HMP-treated rats, while clofibrate induced large increases in CAT activity, which were significant compared to control and HMP values. While having chemical structural similarity to clofibrate, HMP appears to cause comparable hypocholesterolemic activity without comparable levels of hepatomegaly and peroxisome proliferation.
D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D002332:Carnitine O-Acetyltransferase / Q000032:analysis; D002784:Cholesterol / Q000097:blood*; D002994:Clofibrate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008074:Lipoproteins / Q000097:blood*; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D008297:Male; D008830:Microbodies / Q000187:drug effects*; D051381:Rats
D000924:Anticholesteremic Agents; D008074:Lipoproteins; C030104:lipoprotein cholesterol; C029160:ethyl-(p-chlorophenoxy)-3-hydroxy-3-methylpentanoate; D002784:Cholesterol; D002332:Carnitine O-Acetyltransferase; D002994:Clofibrate