Effects of HMG-CoA reductase inhibition on hepatic expression of key cholesterol-regulatory enzymes and receptors in nephrotic syndrome.
BACKGROUND
Hypercholesterolemia is one of the major manifestations of nephrotic syndrome. We have previously shown that nephrotic hypercholesterolemia is associated with and, in part, due to dysregulation of hepatic HMG-CoA reductase, acyl-CoA:cholesterol acyltransferase (ACAT) and cholesterol 7alpha-hydroxylase, as well as lecithin:cholesterol acyltransferase (LCAT), low-density lipoprotein (LDL) receptor and high-density lipoprotein (HDL) receptor deficiencies. This study was carried out to discern the effect of inhibition of HMG-CoA reductase on expression of the key enzymes and receptors involved in cholesterol metabolism in the liver.


METHODS
Rats with puromycin-induced nephrotic syndrome were treated with either a statin (rosuvastatin 20 mg/kg/day) or placebo for 2 weeks. Placebo-treated normal rats served as controls. Gene expression, protein abundance and/or activities of relevant receptors and enzymes were quantified.


RESULTS
The untreated nephrotic rats showed heavy proteinuria, hypoalbuminemia, hypercholesterolemia, elevated total cholesterol:HDL cholesterol ratio and normal creatinine clearance. This was associated with severe reductions in hepatic LDL receptor, hepatic HDL receptor and plasma LCAT concentration, marked upregulation of hepatic ACAT, and unchanged cholesterol 7alpha-hydroxylase (rate-limiting step in cholesterol catabolism). Statin administration for 2 weeks ameliorated hepatic LDL receptor and HDL receptor deficiencies and significantly lowered plasma cholesterol, LDL cholesterol, total cholesterol:HDL cholesterol ratio and proteinuria.


CONCLUSIONS
HMG-CoA reductase inhibition improved hepatic LDL and HDL receptor deficiencies, and ameliorated the associated hyperlipidemia in the nephrotic rats.
Vaziri
Nosratola D
ND
Division of Nephrology and Hypertension, University of California, Irvine, Orange, Calif. 92868, USA. ndvaziri@uci.edu
Liang
Kaihui
K
D000818:Animals; D002784:Cholesterol / Q000378:metabolism*; D002790:Cholesterol 7-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism; D005464:Fluorobenzenes / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D008075:Lipoproteins, HDL / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D009404:Nephrotic Syndrome / Q000188:drug therapy* / Q000378:metabolism; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000235:genetics / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011973:Receptors, LDL / Q000378:metabolism; D018110:Receptors, Lipoprotein / Q000378:metabolism; D000068718:Rosuvastatin Calcium; D002785:Sterol O-Acyltransferase / Q000235:genetics / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology*; D000097587:Sterol O-Acyltransferase 2
D002784:Cholesterol; D002790:Cholesterol 7-alpha-Hydroxylase; D005464:Fluorobenzenes; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D008075:Lipoproteins, HDL; D007862:Phosphatidylcholine-Sterol O-Acyltransferase; D011743:Pyrimidines; D011973:Receptors, LDL; D018110:Receptors, Lipoprotein; D000068718:Rosuvastatin Calcium; D002785:Sterol O-Acyltransferase; D013449:Sulfonamides; D000097587:Sterol O-Acyltransferase 2; C031616:high density lipoprotein receptors