Hypercholesterolaemia, hypotriacylglycerolaemia and increased lipoprotein lipase activity following orchidectomy in rats

1986 ◽  
Vol 113 (1) ◽  
pp. 133-139 ◽  
Author(s):  
Anna Haug ◽  
Arne T. Høstmark ◽  
Øystein Spydevold ◽  
Einar Eilertsen
Keyword(s):  
Lipoprotein Lipase ◽  
Hepatic Lipase ◽  
Plasma Cholesterol ◽  
Cholesterol Acyltransferase ◽  
Plasma Lipoproteins ◽  
Cholesterol Concentration ◽  
Hepatic Cholesterol ◽  
Faecal Excretion ◽  
Testosterone Substitution ◽  
Cholesterol Excretion

Abstract. Plasma lipoproteins, faecal cholesterol excretion, and activities of lecithin: cholesterol acyltransferase (LCAT) hepatic lipase (HL), and lipoprotein lipase (LPL) were determined in castrated rats, in rats treated with testosterone propionate after castration, and in sham-operated controls. Compared to control rats, whole-plasma total cholesterol (TC) rose, and triacylglycerols (TG) fell in castrated rats, but were normalized by androgen substitution. VLDL components tended to be reduced, whereas HDL2 components rose following castration. In general, testosterone substitution normalized the alterations induced by castration. Adipose tissue LPL was higher in castrated rats than in control rats, whereas activities of HL and LCAT were not significantly affected by the treatments. Hepatic cholesterol concentration, and faecal excretion of cholesterol and bile acids were not significantly altered by the treatments. Considering all 3 groups together, there was a significant positive correlation between the concentration of plasma cholesterol and cholesterol in liver, between plasma HDL2-cholesteryl esters and hepatic cholesterol, and also between HL and faecal cholesterol excretion. The results suggest that short term castration of rats causes increased levels of lipoprotein lipase and thereby brings about a lowering of VLDL and an increased concentration of LDL and HDL2. These effects are reflected in hypotriacylglycerolaemia and hypercholesterolaemia.

Dyslipoproteinaemia in hypothyroidism of pituitary origin: effects of l-thyroxine substitution on lipoprotein lipase, hepatic lipase, and on plasma lipoproteins

1983 ◽  
Vol 103 (2) ◽  
pp. 192-197 ◽  
Author(s):  
Stig Valdemarsson ◽  
Pavo Hedner ◽  
Peter Nilsson-Ehle
Keyword(s):  
Lipoprotein Lipase ◽  
Hepatic Lipase ◽  
Plasma Cholesterol ◽  
Elimination Rate ◽  
Lipoprotein Metabolism ◽  
Hdl Cholesterol ◽  
Primary Hypothyroidism ◽  
Plasma Lipoproteins ◽  
Control Group ◽  
Secondary Hypothyroidism

Abstract. We have studied the effects of l-thyroxine substitution on lipoprotein concentrations, on the activities of lipoprotein lipase (LPL) and hepatic lipase (HL), and on the elimination rate of exogenous triglyceride in a homogeneous group of patients with hypothyroidism of pituitary origin. All were deficient of sex hormones but not of corticosteroids during the observation period. Before treatment total plasma cholesterol, LDL cholesterol, and triglyceride levels were significantly higher than in a euthyroid control group but not as high as in patients with overt primary hypothyroidism. The activities of LPL and HL were also intermediate between those of euthyroid and overt primary hypothyroid subjects, and there was a significant reduction of the elimination rate of exogenous triglyceride. No changes were found for HDL cholesterol levels. When the patients with secondary hypothyroidism were compared to patients with primary hypothyroidism, matched for thyroid function levels, age, sex, and weight, there were no differences with regard to plasma lipoprotein concentrations or post-heparin lipase activities. In 3 patients with secondary hypothyroidism the lipoprotein profiles were studied by zonal ultracentrifugation and found to agree well with changes observed in primary hypothyroidism. l-thyroxine substitution produced a normalization of lipase activities and lipoprotein concentrations in patients with secondary hypothyroidism. We conclude that there are no fundamental differences in the disturbances of the lipoprotein metabolism in primary and secondary forms of hypothyroidism.

scholarly journals Selective and independent associations of phospholipid transfer protein and hepatic lipase with the LDL subfraction distribution

2002 ◽  
Vol 43 (8) ◽  
pp. 1256-1263 ◽  
Author(s):  
Susan J. Murdoch ◽  
Molly C. Carr ◽  
Hal Kennedy ◽  
John D. Brunzell ◽  
John J. Albers
Keyword(s):  
Hepatic Lipase ◽  
Premenopausal Women ◽  
Plasma Lipoproteins ◽  
Cholesterol Concentration ◽  
Phospholipid Transfer Protein ◽  
Transfer Protein ◽  
Phospholipid Transfer ◽  
Pltp Activity ◽  
Hdl Metabolism ◽  
Relationship Of

Phospholipid transfer protein (PLTP), hepatic lipase (HL), and lipoprotein lipase (LPL) have all been reported to be intricately involved in HDL metabolism but the effect of PLTP on the apolipoprotein B-containing lipoproteins relative to that of HL and LPL has not been established. Due to our previous observation of a positive correlation of PLTP activity with plasma apoB and LDL cholesterol, the relationship of PLTP with the LDL subfractions was investigated and compared with that of HL and LPL. Plasma lipoproteins from 50 premenopausal women were fractionated by density gradient ultracentrifugation. Correlations were calculated between the cholesterol concentration of each fraction and plasma PLTP, HL, and LPL activity. Plasma PLTP activity was highly, positively, and selectively correlated with the cholesterol concentration of the buoyant LDL/dense IDL fractions, yet demonstrated a complete absence of an association with the dense LDL fractions. In contrast, HL was positively correlated with the dense LDL fractions but showed no association with buoyant LDL. LPL was also positively correlated with several buoyant LDL fractions; however, the correlations were weaker than those of PLTP. PLTP and LPL were positively correlated and HL was negatively correlated with HDL fractions.The results suggest that PLTP and HL may be important and independent determinants of the LDL subpopulation density distributions.

High plasma cholesterol in drug-induced cholestasis is associated with enhanced hepatic cholesterol synthesis

1999 ◽  
Vol 276 (5) ◽  
pp. G1165-G1173 ◽  
Author(s):  
Jeffrey W. Chisholm ◽  
Patrick Nation ◽  
Peter J. Dolphin ◽  
Luis B. Agellon
Keyword(s):  
Bile Acids ◽  
Cholesterol Synthesis ◽  
Cell Membranes ◽  
Reductase Activity ◽  
Plasma Cholesterol ◽  
Hepatic Cell ◽  
Plasma Lipoproteins ◽  
Liver Cholesterol ◽  
Hepatic Cholesterol ◽  
Hepatic Cholesterol Synthesis

In α-naphthylisothiocyanate-treated mice, plasma phospholipid (PL) levels were elevated 10- and 13-fold at 48 and 168 h, respectively, whereas free cholesterol (FC) levels increased between 48 h (17-fold) and 168 h (39-fold). Nearly all of these lipids were localized to lipoprotein X-like particles in the low-density lipoprotein density range. The PL fatty acyl composition was indicative of biliary origin. Liver cholesterol and PL content were near normal at all time points. Hepatic hydroxymethylglutaryl CoA reductase activity was increased sixfold at 48 h, and cholesterol 7α-hydroxylase activity was decreased by ∼70% between 24 and 72 h. These findings suggest a metabolic basis for the appearance of abnormal plasma lipoproteins during cholestasis. Initially, PL and bile acids appear in plasma where they serve to promote the efflux of cholesterol from hepatic cell membranes. Hepatic cholesterol synthesis is then likely stimulated in the response to the depletion of hepatic cell membranes of cholesterol. We speculate that the enhanced synthesis of cholesterol and impaired conversion to bile acids, particularly during the early phase of drug response, contribute to the accumulation of FC in the plasma.

scholarly journals Hypocholesterolaemic effect of β β'-methyl-substituted hexadecanedioic acid (MEDICA 16) in the male hamster

1993 ◽  
Vol 289 (3) ◽  
pp. 911-917 ◽  
Author(s):  
N Mayorek ◽  
J Bar-Tana
Keyword(s):  
Cholesteryl Ester ◽  
Cholesterol Efflux ◽  
Free Cholesterol ◽  
Plasma Cholesterol ◽  
Cholesterol Acyltransferase ◽  
Cholesterol Content ◽  
Plasma Lipoproteins ◽  
Purina Chow ◽  
Apolipoprotein C ◽  
Bile Cholesterol

Treatment of cholesterol-fed male hamsters kept on a diet of purina chow with beta beta'-methyl-substituted hexadecanedioic acid (MEDICA 16) resulted in a progressive hypocholesterolaemic effect, amounting to a 50% decrease in the cholesterol content of all plasma lipoproteins. The decrease in plasma cholesterol could be accounted for by activation of plasma-cholesterol efflux through the liver into the bile mediated by MEDICA 16-induced (a) increase of the number of liver LDL receptors, (b) activation of liver neutral cholesteryl ester hydrolase with a concomitant inhibition of liver acyl-CoA cholesterol acyltransferase, resulting in shifting of the liver cholesteryl ester/free-cholesterol cycle in the direction of free cholesterol, and (c) activation of cholesterol efflux from the liver into the bile. The increase in bile cholesterol output was accompanied by an increase in bile phospholipids but not in bile acids. In contrast with rats, MEDICA 16-treatment of male hamsters did not result in a hypotriacylglycerolaemic effect, inhibition of lipogenesis, nor in a substantial decrease in plasma apolipoprotein C-III content.

INCREASED FACTOR VII REACTIVITY IN THE RABBIT FOLLOWING DIET-INDUCED HYPERCHOIESTEROIAEMIA

1987 ◽  
Author(s):  
K A Mitropoulos ◽  
S J Walter ◽  
T W Meade ◽  
M P Esnouf
Keyword(s):  
Plasma Cholesterol ◽  
Plasma Lipid ◽  
Density Lipoprotein ◽  
Fold Increase ◽  
Plasma Lipoproteins ◽  
Cholesterol Concentration ◽  
Factor Vii ◽  
Standard Diet ◽  
Factor X ◽  
Single Chain

The association of factor VII coagulant activity (VIIC) with plasma lipid concentrations has been a consistent feature of a number of studies in man and points to plasma lipoproteins as determinants of VIIC.To modify plasma lipoprotein concentrations and to study the effect of this on VIIC, rabbits were fed a 1%- cholesterol-supplemented diet. Treatment resulted in a many-fold increase in plasma cholesterol concentration with the major fraction of excess cholesterol associated with the very low and intermediate density lipoprotein fractions. VIIC was considerably higher in rabbits fed 1%- cholesterol-supplemented than in rabbits fed the standard diet. In both groups of rabbits, the direction and extent of variation in VIIC coincided with variation in cholesterol concentration so that over time there were significant and positive correlations between VIIC and plasma cholesterol. A method that provides a measure of the total functionalfactor VII concentration (VII) was also used. This assay involves clotting the plasma in the presence of excess tissue factor and therefore the conversion of VII tothe more reactive two-chain form of theprotein (αVIIa) .The concentration of αVIIa present in the serum was measured from the rate of activation of excess of [sialyl-3H]-bovine factor X. By day 10 of treatment, and in all furthercomparisons VTIt was only slightly higher in the group of rabbits fed cholesterol-supplemented than in that fed the standard diet.This increase in VI11 istoo small to explain the considerable increasin VIIC in the hypercholesterolaemic rabbit. We conclude thattheincrease in VIIc was to ahigher proportion of αVIIa in theplasma of hyperchol⋆esterol-aemic rabbits rather thanto an increase in the concentration of the single-chain protein.

Testosterone substitution increases the activity of lipoprotein lipase and hepatic lipase in hypogonadal males

1988 ◽  
Vol 69 (2-3) ◽  
pp. 191-197 ◽  
Author(s):  
Ritva Sorva ◽  
Timo Kuusi ◽  
Marja-Riita Taskinen ◽  
Jaakko Perheentupa ◽  
Esko A. Nikkilä
Keyword(s):  
Lipoprotein Lipase ◽  
Hepatic Lipase ◽  
Testosterone Substitution
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