HMG-CoA reductase inhibition reverses LCAT and LDL receptor deficiencies and improves HDL in rats with chronic renal failure

2005 ◽  
Vol 288 (3) ◽  
pp. F539-F544 ◽  
Author(s):  
K. Liang ◽  
C. H. Kim ◽  
N. D. Vaziri

Dyslipidemia is a prominent feature of chronic renal failure (CRF) and a major risk factor for atherosclerosis and the progression of renal disease. CRF-induced dyslipidemia is marked by hypertriglyceridemia and a shift in plasma cholesterol from HDL to the ApoB-containing lipoproteins. Several studies have demonstrated a favorable response to administration of 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitors (statins) in CRF. This study was intended to explore the effect of statin therapy on key enzymes and receptors involved in cholesterol metabolism. Accordingly, CRF ( nephrectomized) and sham-operated rats were randomized to untreated and statin-treated (rosuvastatin 20 mg·kg−1·day−1) groups and observed for 6 wk. The untreated CRF rats exhibited increased total cholesterol-to-HDL cholesterol ratio, diminished plasma lecithin:cholesterol acyltransferase (LCAT) and the hepatic LDL receptor, elevated hepatic acyl-CoA:cholesterol acyltransferase (ACAT), and no change in hepatic HMG-CoA reductase, cholesterol 7α-hydroxylase, or HDL receptor (SRB-1). Statin administration lowered HMG-CoA reductase activity, normalized plasma LCAT, total cholesterol-to-HDL cholesterol ratio, and hepatic LDL receptor but did not significantly change either plasma total cholesterol, hepatic cholesterol 7α-hydroxylase, total ACAT activity, or SRB-1 in the CRF animals. Statin administration to the normal control rats led to significant increases in plasma LCAT and hepatic LDL receptor, significant reductions of total cholesterol-to-HDL cholesterol ratio, hepatic HMG-CoA reductase activity, and cholesterol 7α-hydroxylase abundance with virtually no change in plasma cholesterol concentration. Thus administration of rosuvastatin reversed LCAT and LDL receptor deficiencies and promoted a shift in plasma cholesterol from ApoB-containing lipoproteins to HDL in CRF rats.

2004 ◽  
Vol 287 (5) ◽  
pp. F1038-F1043 ◽  
Author(s):  
N. D. Vaziri ◽  
K. Liang

Chronic renal failure (CRF) is associated with increased risk of arteriosclerotic cardiovascular disease and profound alteration of plasma lipid profile. Uremic dyslipidemia is marked by increased plasma concentration of ApoB-containing lipoproteins and impaired high-density lipoprotein (HDL)-mediated reverse cholesterol transport. These abnormalities are, in part, due to acquired LCAT deficiency and upregulation of hepatic acyl-CoA:cholesterol acyltransferase (ACAT). ACAT catalyzes intracellular esterification of cholesterol, thereby promoting hepatic production of ApoB-containing lipoproteins and constraining HDL-mediated cholesterol uptake in the peripheral tissues. In view of the above considerations, we tested the hypothesis that pharmacological inhibition of ACAT may ameliorate CRF-induced dyslipidemia. 5/6 Nephrectomized rats were treated with either ACAT inhibitor IC-976 (30 mg·kg−1·day−1) or placebo for 6 wk. Sham-operated rats served as controls. Key cholesterol-regulating enzymes, plasma lipids, and creatinine clearance were measured. The untreated CRF rats exhibited increased plasma low-density lipoprotein (LDL) and very LDL (VLDL) cholesterol, unchanged plasma HDL cholesterol, elevated total cholesterol-to-HDL cholesterol ratio, reduced liver microsomal free cholesterol, and diminished creatinine clearance. This was accompanied by reduced plasma LCAT, increased hepatic ACAT-2 mRNA, ACAT-2 protein and ACAT activity, and unchanged hepatic HMG-CoA reductase and cholesterol 7α-hydroxylase. ACAT inhibitor raised plasma HDL cholesterol, lowered LDL and VLDL cholesterol, and normalized total cholesterol-to-HDL cholesterol ratio without changing total cholesterol concentration (hence, a shift from ApoB-containing lipoproteins to HDL). This was accompanied by normalizations of hepatic ACAT activity and plasma LCAT. In conclusion, inhibition of ACAT reversed LCAT deficiency and improved plasma HDL level in CRF rats. Future studies are needed to explore the efficacy of ACAT inhibition in humans with CRF.


2021 ◽  
Vol 5 ◽  
Author(s):  
H. P. Mohankumari ◽  
K. Akhilender Naidu ◽  
K. Narasimhamurthy ◽  
G. Vijayalakshmi

Monascus purpureus is known to produce pigment molecules. The pigments were extracted from M. purpureus fermented rice. In-vitro antioxidant effects of pigments were observed and presumed to alleviate oxidative stress related atherosclerosis effect in rats fed with high fat diet (HFD) for 14 weeks. The formation of lipid peroxide due to the oxidation of serum lipid was higher in rats fed with HFD. While, the feeding of fermented rice (groups III-V) significantly lowered the formation of lipid peroxide (27.1–51.7%) in serum of rats, indicated antioxidative effect of pigments. In addition, feeding of fermented rice lowered serum cholesterol and triacylglycerol by 44.82 and 45.30%, respectively. Whereas, LDL-cholesterol levels were decreased by 70.12% and HDL-cholesterol increased by 34.58%. The atherogenic indices (LDL/HDL and TC/HDL) were reduced by 77.80 and 61.05%, respectively, in rats fed with fermented rice. These data confirmed the anti-atherosclerotic effect of pigments. Further liver enzyme, 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity was significantly inhibited up to 54%. The identification of statins, sterols and fatty acids in fermented rice revealed the HMG-CoA reductase inhibitory activity. This was confirmed by synthesis of lower levels of cholesterol and triacylglycerol in liver of rats fed with fermented rice. Accordingly antioxidant, inhibition of HMG-CoA reductase, anti-atherogenic functions of M. purpureus fermented rice is attributed to the collective effect of bioactive metabolites.


1997 ◽  
Vol 78 (3) ◽  
pp. 493-500 ◽  
Author(s):  
F. Nassir ◽  
C. Moundras ◽  
D. Bayle ◽  
C. Sérougne ◽  
E. Gueux ◽  
...  

Since experimental Se deficiency results in a significant increase in plasma cholesterol concentration the present investigation was undertaken to assess further the influence of this deficiency on the expression of proteins involved in hepatic lipid metabolism. Se deficiency was induced by feeding weanling male Wistar rats on a deficient diet for 6 weeks. Hypercholesterolaemia associated with Se deficiency was related to increased 3-hydroxy-3-methylglutaryl-coA (HMG-CoA) reductase (EC 1.1.1.34) activity in liver microsomes as compared with control animals. Hepatic lipoprotein receptor levels (LDL-receptor and HDL-binding proteins, HB1 and HB2) were not significantly affected by Se deficiency, as assessed by immunoblotting. Plasma triacylglycerol concentrations tended to decrease in Se-deficient rats in concert with their reduced post-Triton secretion. There was no significant effect of Se deficiency on the hepatic synthesis of apolipoproteins. These results point to the need for further investigations into the mechanism related to the increased activity of HMG-CoA reductase and the enhanced cholesterogenesis in the liver of Se-deficient rats likely to result from this.Selenium: Cholesterol: Triacylglycerol: HMG-CoA reductase


1992 ◽  
Vol 263 (2) ◽  
pp. E287-E295
Author(s):  
F. Alarrayed ◽  
A. D. Hartman ◽  
J. R. Porter

We tested the hypothesis that hypercorticosteronemia causes the hypercholesterolemia in young developing "fatty" rats. Obesity induced increases in corticosterone. Insulin, glucose, body weight, average daily food intake, plasma triglyceride, plasma phospholipids, liver weight, liver triglyceride, various adipose tissue parameters, and liver hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase activity were all ameliorated by adrenalectomy. Adrenalectomy exacerbated the hypercholesterolemia in obese animals and induced it in lean rats. Changes or lack of change in hepatic microsomal cholesterol, HMG-CoA reductase, and 7 alpha-hydroxylase, combined with the adrenalectomy-induced curtailment of tissue storage of cholesterol in adipose tissue, all contribute to the hypercholesterolemia caused by adrenalectomy. We suggest a mechanism whereby this may be related to elevated hepatic very low-density lipoprotein secretion rates. The elevated HMG-CoA reductase activity in obese rats results from the lower liver microsomal free cholesterol content. We conclude that the absence of glucocorticoids does not directly reduce plasma cholesterol in obese Zucker rats. The surprising elevation of cholesterol by adrenalectomy is due to other prevailing mechanisms in liver and adipose tissue, which curtail their capacity to store cholesterol.


1992 ◽  
Vol 26 (4) ◽  
pp. 269-280 ◽  
Author(s):  
Jaap Joles ◽  
Nel Willekes-Koolschijn ◽  
Hein Koomans ◽  
Arie van Tol ◽  
Tini Geelhoed-Mieras ◽  
...  

Recent reports demonstrate a hypocholesterolaemic effect of daily subcutaneous injections of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors in different rat models of hyperlipidaemia. However, this effect is not seen after oral administration of HMG-CoA reductase inhibitors in rats. We found that oral administration of the HMG-CoA reductase inhibitor Simvastatin also had no effect on plasma cholesterol in severely hyperlipidaemic Nagase analbuminaemic rats (NAR). Simvastatin (an apolar compound dissolved in propylene glycol) was infused continuously for 28 days into the subcutis of control Sprague-Dawley rats (SDR) and NAR using an implanted osmotic pump. All doses which were effective in reducing cholesterol in the NAR (reductions up to -60%), reduced apolipoprotein AI but not apolipoprotein B and caused a severe inflammatory reaction in the dermis. Similar toxicity was observed in the SDR. Subcutaneous administration of the vehicle (propylene glycol) did not cause this reaction and did not affect plasma lipids. Administration of Lovastatin in osmotic pumps resulted in a similar inflammatory reaction. Incorporation of Simvastatin into liposomes did not diminish the toxic effect. On the other hand, infusion of Pravastatin (a polar HMG-CoA reductase inhibitor dissolved in isotonic saline) caused no changes in the dermis and had no effect on plasma lipids in NAR or SDR. Liver microsomes prepared from the Pravastatin-treated rats demonstrated a 3- to 4-fold increase in HMG-CoA reductase activity as compared to untreated rats, confirming uptake of the drug. We conclude that continuous subcutaneous administration of the HMG-CoA reductase inhibitors Simvastatin, Lovastatin and Pravastatin for 28 days may not reduce plasma cholesterol in rats by a mechanism which is related to inhibition of HMG-CoA reductase activity in the liver. The decrease of plasma cholesterol effected by subcutaneous infusion of Simvastatin or Lovastatin in NAR coincides with, and may be related to inflammatory changes caused by administering these compounds into the dermis.


PLoS ONE ◽  
2011 ◽  
Vol 6 (11) ◽  
pp. e20516 ◽  
Author(s):  
Ioanna Vallianou ◽  
Nikolaos Peroulis ◽  
Panayotis Pantazis ◽  
Margarita Hadzopoulou-Cladaras

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