Regulation of hepatic cholesterogenesis by polar steroids accumulated after cholesterol feeding

1988 ◽  
Vol 8 (2) ◽  
pp. 155-162 ◽  
Author(s):  
Juan A. Aguilera ◽  
Virginia García-Molina ◽  
Victor Arce ◽  
Eduardo García-Peregrín
Keyword(s):  
Physiological Function ◽  
Reductase Activity ◽  
Cholesterol Feeding ◽  
First Report ◽  
Coa Reductase ◽  
Hepatic Cholesterogenesis

The incorporation of mevalonate into nonsaponifiable lipids by chick liver in vivo strongly increased between 1–18 days after hatching. Cholesterol feeding (2%) inhibited this. Synthesis of cholesterol was strongly inhibited, whereas the intermediates isolated by TLC accumulated. Most of the polar nonsaponifiable lipids that accumulated in liver 90 minutes after mevalonate administration to 18-day-old cholesterol-fed chicks were identified as lanosterol derivative. 3-Hydroxy-3-methylglutaryl-CoA reductase activity, as well as acetate and mevalonate incorporation into nonsaponifiable lipids, was inhibited by the presence of these compounds. To our knowledge, this is the first report of such inhibition; this confirms the physiological function of polar steroids in the regulation of cholesterogenesis in vivo.

scholarly journals Regulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity in mouse uterine epithelial cells

1987 ◽  
Vol 241 (1) ◽  
pp. 279-284 ◽  
Author(s):  
L Leijten ◽  
P A Wilce ◽  
M Davidson ◽  
M Banks ◽  
L Martin
Keyword(s):  
Enzyme Activity ◽  
Epithelial Cells ◽  
Reductase Activity ◽  
Active Form ◽  
Cholesterol Feeding ◽  
Uterine Epithelial Cells ◽  
Coa Reductase ◽  
Inhibited Enzyme

The regulation of 3-hydroxy-3-methylglutaryl-CoA reductase was studied in mouse uterine epithelium. The enzyme was rapidly inactivated during incubation with ATP/Mg2+ in vitro, and could be re-activated by incubation with partially purified rat liver phosphoprotein phosphatase. Enzyme activity was rapidly inhibited by mevalonate injection in vivo to approx. 30% of control. The percentage of total enzyme active in vivo was measured by inclusion of NaF in the isolation buffers. The percentage of enzyme active in vivo 18 h after stimulation by oestrogens remained at approx. 25% after inhibition of activity by mevalonate injection, cholesterol feeding or progesterone pretreatment. However, 9 h after oestrogen stimulation, cholesterol feeding inhibited enzyme activity to 57% of control, 94% of which was in the active form. We conclude that, although all components for a reversible phosphorylative regulation of 3-hydroxy-3-methylglutaryl-CoA reductase activity are present in uterine epithelial cells, a role in the rapid changes in epithelial enzyme activity has not been demonstrated.

scholarly journals Hepatic and intestinal formation of polar sterols in vivo in animals fed on a cholesterol-supplemented diet

1988 ◽  
Vol 252 (2) ◽  
pp. 395-399 ◽  
Author(s):  
C Marco de la Calle ◽  
G F Gibbons
Keyword(s):  
Reductase Activity ◽  
Lipid Fraction ◽  
Dietary Cholesterol ◽  
Lipid Synthesis ◽  
Inverse Correlation ◽  
Normal Diet ◽  
Hmg Coa Reductase ◽  
Coa Reductase ◽  
Strong Inverse Correlation

In rats fed on a diet containing 1% cholesterol for 24 h, the decrease in hepatic non-saponifiable lipid synthesis, cholesterogenesis and 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity was accompanied by an increase in the proportion of newly synthesized polar sterols in vivo. In these animals there was also a strong inverse correlation between the proportion of polar sterols in the non-saponifiable lipid and hepatic HMG-CoA reductase activity. A similar correlation was not observed in animals fed on a normal diet. Cholesterogenesis in the intestine was not as sensitive to inhibition by dietary cholesterol as was that in the liver, and there was no increase in the polar-sterol content of the newly synthesized non-saponifiable-lipid fraction.

scholarly journals Role of reversible phosphorylation in mediating changes in the activity of hepatic 3-hydroxy-3-methylglutaryl-CoA reductase during pregnancy and lactation in the rat

1987 ◽  
Vol 248 (3) ◽  
pp. 993-996 ◽  
Author(s):  
R A Easom ◽  
V A Zammit
Keyword(s):  
Reductase Activity ◽  
Post Partum ◽  
Active Form ◽  
Total Activity ◽  
Female Rats ◽  
Hmg Coa Reductase ◽  
Pregnancy And Lactation ◽  
Coa Reductase

1. The expressed and total (completely dephosphorylated) activities of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase were measured in microsomal fractions isolated from cold-clamped liver samples from female rats in various stages of the reproductive cycle. 2. There was little change in total HMG-CoA reductase activity during pregnancy and early lactation, but after 2 days post partum there was a marked increase in total activity. 3. The expressed/total activity ratio of HMG-CoA reductase showed a profound decrease during the last 2 days of pregnancy. The fraction of the enzyme in the active form increased progressively during the first 2 days of lactation. 4. The combined effect of these changes was that the expressed activity of HMG-CoA reductase changed in parallel with the known changes in the hepatic rate of cholesterogenesis during pregnancy and lactation in vivo.

scholarly journals Regulation of cholesterol synthesis in the liver and mammary gland of the lactating rat

1983 ◽  
Vol 212 (3) ◽  
pp. 843-848 ◽  
Author(s):  
G F Gibbons ◽  
C R Pullinger ◽  
M R Munday ◽  
D H Williamson
Keyword(s):  
Mammary Gland ◽  
Inverse Relationship ◽  
Cholesterol Synthesis ◽  
Reductase Activity ◽  
Significant Decline ◽  
High Fat ◽  
Hmg Coa Reductase ◽  
Lactating Mammary Gland ◽  
Coa Reductase

The activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase; EC 1.1.1.34) in the lactating mammary gland of rats killed between 10:00 and 14:30 h was 2-3 times that in the livers of the same animals. In contrast, after injection of 3H2O in vivo, the rate of appearance of 3H in the cholesterol of the gland was much lower than that in the liver. In the mammary gland of virgin and non-lactating animals, the activity of HMG-CoA reductase was less than 10% of that of the lactating gland. The activity of HMG-CoA reductase in the lactating mammary gland was significantly (P less than 0.005) lower at midnight than at mid-day, and appeared to show an inverse relationship to the activity of the liver enzyme. However, there was no corresponding change in the incorporation of 3H into the gland cholesterol. Withdrawal of food for 6h had no effect on the activity of HMG-CoA reductase in the lactating mammary gland, but resulted in a significant decrease (P less than 0.005) in that of the liver. Starvation of lactating rats for 24h produced a significant decrease (P less than 0.005) in the activity of the enzyme in both organs. There was also a significant decline in the rate at which 3H2O was incorporated in vivo into the cholesterol of both organs (liver, P less than 0.05; gland, P less than 0.005). Giving a high-fat palatable diet together with chow to lactating animals led to a decline in HMG-CoA reductase activity in the mammary gland, but not in liver. This decrease in the gland was not accompanied by a corresponding decline in the apparent rate of cholesterol synthesis.

scholarly journals The Cholesterol-Lowering Effect of Alisol Acetates Based on HMG-CoA Reductase and Its Molecular Mechanism

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Fei Xu ◽  
Hui Yu ◽  
Cai Lu ◽  
Jun Chen ◽  
Wei Gu
Keyword(s):  
Molecular Simulation ◽  
Reductase Activity ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Lipoprotein Cholesterol ◽  
Hmg Coa Reductase ◽  
Coa Reductase ◽  
The Impact

This study measured the impact of alisol B 23-acetate and alisol A 24-acetate, the main active ingredients of the traditional Chinese medicine Alismatis rhizoma, on total cholesterol (TC), triglyceride (TG), high density lipoprotein-cholesterol (HDL-C), and low density lipoprotein-cholesterol (LDL-C) levels of hyperlipidemic mice. The binding of alisol B 23-acetate and alisol A 24-acetate to the key enzyme involved in the metabolism of TC, 3-hydroxy-3-methylglutary-coenzyme A (HMG-CoA) reductase, was studied using the reagent kit method and the western blotting technique combined with a molecular simulation technique. According to the results, alisol acetates significantly lower the TC, TG, and LDL-C concentrations of hyperlipidemic mice, while raising HDL-C concentrations. Alisol acetates lower HMG-CoA reductase activity in a dose-dependent fashion, both in vivo and in vitro. Neither of these alisol acetates significantly lower the protein expression of HMG-CoA. This suggests that alisol acetates lower the TC level via inhibiting the activity of HMG-CoA reductase by its prototype drug, which may exhibit an inhibition effect via directly and competitively binding to HMG-CoA. The side chain of the alisol acetate was the steering group via molecular simulation.

scholarly journals Studies on the response of cholesterol biogenesis in feeding in rats: evidence against the existence of diurnal rhythms

1976 ◽  
Vol 158 (1) ◽  
pp. 53-60 ◽  
Author(s):  
R Fears ◽  
B Morgan
Keyword(s):  
Fatty Acid Biosynthesis ◽  
Diurnal Rhythms ◽  
Cholesterol Feeding ◽  
Acid Biosynthesis ◽  
Accurate Representation ◽  
Ad Libitum ◽  
Hepatic Cholesterogenesis ◽  
Stimulation Of

1. The biosynthesis of cholesterol was studied, by using various precursors, in rats subjected to several dietary regimes. 2. The use of 3H2O as a substrate to demonstrate differences in cholesterogenesis under various conditions was validated by using rats fed on cholesterol or cholestyramine. Cholesterol feeding resulted in decreased cholesterogenesis, whereas cholestyramine caused an increase. 3. With acetate as precursor, the biosynthesis of both digitonin-precipitable sterol and fatty acids was increased in vitro in response to a meal. 4. In rats fed ad libitum, hepatic cholesterogenesis was increased at midnight relative to mid-morning as measured by using acetate precursor in vitro. However, no such difference was found by using 3H2O in vivo. 5. The lipogenic response was measured in meal-fed rats by using 3H2O or octanoate in vivo. In contrast with findings with acetate in vitro, no postprandial stimulation of cholesterogenesis was seen with either 3H2O or octanoate as precursor, whereas fatty acid biosynthesis from either substrate was increased. 6. These findings are discussed with respect to current theories about the circadian rhythm of cholesterogenesis. Such theories are based on experiments using isolated enzyme measurements or non-physiological precursors such as acetate. 7. It is considered that results obtained with 3H2O give an accurate representation of cholesterogenesis under various conditions, and it is therefore suggested that hepatic cholesterogenesis in rats is not subjected to the same degree of diurnal rhythm as has previously been believed.

scholarly journals Novel Phytoconstituents of an Aqueous Pod Extract of Prosopis Cineraria (L.) Druce Attenuate Atherosclerotic Plaque and Hypercholesterolemia in Rabbits

2020 ◽  
Author(s):  
Heera Ram ◽  
Noopur Jaipal ◽  
Pramod Kumar ◽  
Jaykaran Charan ◽  
Priya Kashyap ◽  
...  
Keyword(s):  
Atherosclerotic Plaque ◽  
In Silico ◽  
Reductase Activity ◽  
Hmg Coa Reductase ◽  
Prosopis Cineraria ◽  
Oral Supplementation ◽  
Coa Reductase ◽  
Leading Compounds

Abstract Background and objectives: The pod of Prosopis cineraria traditionally used in several ailments and key component of traditional food recipe of the Panchkuta of western Rajasthan, India. The current study was targeted to assess ability of phytoconstituents of aqueous pod extract of Prosopis cineraria to inhibit HMG-CoA reductase activity and regress atherosclerotic plaque were investigated in in-vitro, in-vivo, and in-silico studies. Material and Methods: LCMS, GCMS, and FTIR analysis were used to characterize the phytoconstituents of the test extract. Accordingly, the in-vitro, in-vivo and in-silico assessments were performed by following the standard methods. Results: The phytochemical results shown the presence of cloprostenol, cinecromen, and dirithromycin as leading compounds. Accordingly, in-vivo assay of test extract shown HMG-CoA inhibition activity by 78.1 % (IC50 was 0.03 μg/ml). Hypercholesterolemia was induced in rabbits through oral supplementation of a high fat diet (21 % fat) with cholesterol powder supplementation. Administration of the test extract caused significant (𝑃 ≤ 0.001) improvement in the lipid profile and antioxidant levels in the test rabbits, relative to the hypercholesterolemic control rabbits. Subsequently, the reductions in the atherosclerotic plaque and improvement in lumen volume were pointedly observed in the treated groups. In-silico analyses of molecular docking and ADMET revealed significant interactions and druggability profile. Conclusion: It can be stated that the phytoconstituents of aqueous pod extract of Prosopis cineraria have the capacity to inhibit HMG-CoA reductase and regress the atherosclerotic plaque which may be beneficial to the treatment of hypercholesterolemia.

scholarly journals Inhibition of HMGcoA reductase by atorvastatin prevents and reverses MYC-induced lymphomagenesis

Blood ◽  
2007 ◽  
Vol 110 (7) ◽  
pp. 2674-2684 ◽  
Author(s):  
Catherine M. Shachaf ◽  
Omar D. Perez ◽  
Sawsan Youssef ◽  
Alice C. Fan ◽  
Sailaja Elchuri ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Mevalonate Pathway ◽  
Reductase Activity ◽  
Facs Analysis ◽  
Cell Sorter ◽  
Atorvastatin Treatment ◽  
Hmgcoa Reductase ◽  
Induced Tumors ◽  
Coa Reductase

Statins are a class of drugs that inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMGcoA) reductase, a critical enzyme in the mevalonate pathway. Several reports document that statins may prevent different human cancers. However, whether or not statins can prevent cancer is controversial due to discordant results. One possible explanation for these conflicting conclusions is that only some tumors or specific statins may be effective. Here, we demonstrate in an in vivo transgenic model in which atorvastatin reverses and prevents the onset of MYC-induced lymphomagenesis, but fails to reverse or prevent tumorigenesis in the presence of constitutively activated K-Ras (G12D). Using phosphoprotein fluorescence-activated cell sorter (FACS) analysis, atorvastatin treatment was found to result in the inactivation of the Ras and ERK1/2 signaling pathways associated with the dephosphorylation and inactivation of MYC. Correspondingly, tumors with a constitutively activated K-Ras (G12D) did not exhibit dephosphorylation of ERK1/2 and MYC. Atorvastatin's effects on MYC were specific to the inhibition of HMGcoA reductase, as treatment with mevalonate, the product of HMG-CoA reductase activity, abrogated these effects and inhibited the ability of atorvastatin to reverse or suppress tumorigenesis. Also, RNAi directed at HMGcoA reductase was sufficient to abrogate the neoplastic properties of MYC-induced tumors. Thus, atorvastatin, by inhibiting HMGcoA reductase, induces changes in phosphoprotein signaling that in turn prevent MYC-induced lymphomagenesis.

scholarly journals Solubility and Bioavailability Enhancement of Poorly Aqueous Soluble Atorvastatin:In Vitro,Ex Vivo, andIn VivoStudies

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Madhuri S. Rodde ◽  
Ganesh T. Divase ◽  
Tejas B. Devkar ◽  
Avinash R. Tekade
Keyword(s):  
Drug Release ◽  
Dissolution Rate ◽  
Ex Vivo ◽  
Reductase Activity ◽  
Polymer Concentration ◽  
Water Soluble ◽  
Hmg Coa Reductase ◽  
Coa Reductase

The objective of this investigation was to improve the solubility of the poorly water soluble drug atorvastatin (ATR), using solid dispersion (SD) techniques, with Neem Gum (NG) as a hydrophilic carrier. The effects of the polymer concentration and method of preparation on the solubility and dissolution rate were studied. The results showed that the solubility of ATR increases with increasing NG concentration. However, dissolution rate of ATR from its SD was dependent on the method used to prepare SD. Anin vitrodrug release study revealed that the solvent evaporation technique is a more convenient and effective method of preparing SD than kneading method. The SD was characterized using DSC, SEM, and XRD study. Anin vivostudy was performed in which the 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG CoA) reductase inhibition activity was measured. A significant reduction in HMG CoA reductase activity was observed with SD of ATR compared with the plain drug. Anex vivoabsorption study was carried out using modified apparatus developed in our laboratory. Thein vitrodrug release andin vivoandex vivostudies clearly demonstrated the potential of hydrophilic NG in enhancing the solubility, dissolution rate, and bioavailability of ATR.

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