Regulation of cholesterol and lipoprotein metabolism in guinea pigs mediated by dietary fat quality and quantity.

The effects of dietary fat quality and quantity on regulation of cholesterol and lipoprotein metabolism were measured in guinea pigs. The animals were fed 7.5 or 15% (wt/wt) fat diets containing either polyunsaturated corn oil (CO), monounsaturated olive oil (OL) or saturated lard as the fat source. Dietary fat quality had a number of significant effects: animals fed the CO-based diet had lower plasma LDL levels and LDL particles of higher density with decreased ratios of core-to-surface components. Apoprotein B/E receptor-mediated binding of LDL to hepatic membranes was twofold higher for animals fed the CO-based diet. Animals fed the OL-based diet had lower hepatic 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity and increased levels of hepatic cholesterol. Hepatic cholesteryl ester levels were lowest for animals fed the lard-based diet. Increasing dietary fat quantity resulted in increased plasma LDL levels and hepatic cholesterol, HMG-CoA reductase activity and receptor affinity for LDL. No changes were observed in LDL binding. These data demonstrate that, independent of dietary fat quantity, CO-based diets lower plasma LDL levels, modify LDL composition and increase hepatic apoprotein B/E receptor number.     

Evidence that polyunsaturated lecithin induces a reduction in plasma cholesterol level and favorable changes in lipoprotein composition in hypercholesterolemic rats

For 30 d adult rats were fed a hypercholesterolemic (H) diet (25% saturated fat, 1% cholesterol and 0.5% cholic acid) containing different amounts of saponins (1% or 0.2%) and/or purified polyunsaturated lecithin (2.5% or 0.7%). Lecithin induced a striking reduction in the plasma levels of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) cholesterol as well as an increase in the level of high density lipoprotein (HDL) cholesterol. Saponins had only a very slight effect in lowering the level of VLDL cholesterol. Apoprotein A-I was unexpectedly present in VLDL, IDL and LDL after feeding rats the H diet and disappeared only after lecithin feeding. The activity of plasma lecithin-cholesterol acyltransferase was higher when the two lecithin diets were fed than when the other diets were fed. Fecal excretion of neutral sterols was unmodified by the various diets whereas acid steroid excretion increased after lecithin feeding. Saponins, when added with lecithin to the diet, reduced the beneficial effect of lecithin. The results indicate that polyunsaturated lecithin induced a reduction in plasma cholesterol, possibly through an increased formation of HDL particles.     

Soluble oat fiber tends to normalize lipoprotein composition in cholesterol-fed rats

The effect of oat fiber on VLDL, LDL and HDL composition was investigated by feeding male Sprague-Dawley rats diets containing 1.0% cholesterol and 0.2% cholic acid, and 6% dietary fiber from oat bran, high-fiber oat flour or a processed oat product for 20 d. Compared to cholesterol-fed cellulose controls, all oat fibers altered the response to cholesterol feeding as indicated by 25-45% lower total lipoprotein cholesterol, 40-60% lower VLDL + LDL cholesterol, and 25-40% higher HDL cholesterol contents, P less than 0.01. The effect of the oat fibers on VLDL composition was especially pronounced as demonstrated by 30-65% lower VLDL protein, VLDL apo E and plasma apo B concentrations. The processed oat product which contained 40% more soluble fiber than oat bran or oat flour normalized the lipoprotein profile associated with ingestion of the atherogenic diet significantly more than oat bran or oat flour. Concentration of total lipoprotein cholesterol and distribution of apo E among the VLDL and LDL fractions in the processed oat product group were similar to controls not fed cholesterol. These data indicate that ingestion of oat fiber tends to normalize the lipoprotein profile induced by feeding an atherogenic diet in the rat, and that the hypocholesterolemic effect of oat fiber is associated with its soluble fiber content.     

The hypocholesterolemic effect of high amylose cornstarch in rats is mediated by an enlarged bile acid pool and increased fecal bile acid excretion,not by cecal fermented products

Sham-operated and cecectomized rats were fed for 21 d a cholesterol-free purified diet containing (200 g/kg) either normal cornstarch (CS) or high amylose cornstarch (HACS). In both types of rats, those fed the HACS diet had a significantly lower plasma total cholesterol concentration and a significantly larger intestinal bile acid pool than those fed the CS diet. In cecectomized rats, those fed the HACS diet had significantly lower plasma HDL and LDL cholesterol concentrations, a significantly greater fecal bile acid excretion and a significantly lower hepatic 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase mRNA concentration than those fed the CS diet. The plasma triglyceride concentration and LDL-receptor mRNA concentration were not affected by the diet or cecectomy. In sham-operated rats, the propionate concentration in the cecal contents was significantly greater in those fed the HACS diet than in those fed the CS diet. Compared with sham-operated rats, cecectomized rats had significantly enhanced cholesterol 7alpha-hydroxylase activity. In intact rats, biliary bile acid flux into the small intestine was significantly greater in those fed the HACS diet than in those fed the CS diet. Thus, the hypocholesterolemic effect of HACS appears to be mediated by accelerated fecal excretion of bile acids and increases in the intestinal pool and biliary flux of bile acids, and not by cecal fermentation products.     

Plasma lipid and lipoprotein responses of rats to starch and sucrose diets with and without brewer's yeast.

The effect of starch and sucrose diets, with and without brewer's yeast, on plasma total cholesterol and triglyceride concentration and on the lipoprotein distribution in plasma was studied in male rats. The rats were fed a cereal based stock diet, a starch or a sucrose diet, plus or minus brewer's yeast, for 4 weeks. The plasma cholesterol concentration increased to similar levels in rats fed the starch or the sucrose diets but remained unchanged in rats fed the stock diet. The plasma triglyceride level increased in rats fed stock diet, but was unchanged in those fed starch or sucrose diets. Brewer's yeast did not modify the cholesterol value in any of the three groups but reduced the triglyceride level in rats fed the stock and the starch diets. In rats fed the starch diet there was a reduction in the relative amount of prebeta lipoproteins, but no significant alterations in the beta, prealpha and alpha fractions, as compared with rats fed stock diet. Rats fed the sucrose diet had lower prebeta, beta and alpha lipoprotein percentages and a much higher prealpha percentage than rats fed the stock diet. Brewer's yeast had no consistent effects on the lipoprotein distribution. The results support the contention that there might be a dissociation between dietary effects on the plasma lipid level and on the lipoprotein distribution.     

Plasma lipoprotein cholesterol in rats fed a diet enriched in chitosan and cholesterol

To investigate the effect of dietary chitosan on plasma lipoprotein cholesterol metabolism, male Sprague-Dawley (SD) rats fed a cholesterol-enriched diet containing cellulose (CE) or chitosan (CS) were studied for 2 wk. Lower plasma total cholesterol, low-density lipoprotein (LDL) cholesterol and very-low-density lipoprotein (VLDL) cholesterol were observed in rats fed a diet containing chitosan. In addition, significantly higher high-density lipoprotein (HDL) cholesterol and HDL2 cholesterol were observed in rats after 2 wk of chitosan feeding. Rats fed the chitosan diet had increased triacylglycerol percentages and decreased free cholesterol, cholesteryl ester and phospholipid percentages in VLDL lipid composition. Chitosan significantly decreased the surface lipid proportions and increased the core lipid proportions in VLDL particles. In addition, the ratios of surface lipids to core lipids of the VLDL particles in rats fed a diet containing chitosan were significantly decreased. A significantly lower plasma apolipoprotein B (Apo B) concentration was observed in rats fed the chitosan diet as compared to those fed the cellulose diet. No significant difference in plasma triacylglycerols or glucose levels was observed between the two dietary groups. Results from this study suggest that chitosan may alter the VLDL particle size and also play an important role in the regulation of lipoprotein metabolism in rats.     

Effect of vitamin C depletion on serum cholesterol and lipoprotein levels in ODS (od/od) rats unable to synthesize ascorbic acid

The effect of ascorbic acid deficiency on serum and liver cholesterol, phospholipid and triglyceride levels, serum lipoprotein levels and serum lipoprotein cholesterol levels were examined in male rats with a hereditary defect in ascorbic acid synthesis (ODS rats). Male homozygotes (od/od) and male rats of their parent strain (+/+) were each divided into four treatment groups and were fed vitamin C-deficient or vitamin C-replete diets containing either 0 or 0.5% cholesterol. During the 3-wk feeding-period the ODS (od/od) rats fed the vitamin C-deficient diet gradually decreased food intake, resulting in a lower body weight than that of od/od rats given ascorbic acid. The serum cholesterol level was significantly higher in the vitamin C-deficient od/od rats fed the cholesterol diet, and it tended to be higher in those fed the control (0% cholesterol) diet, whereas the liver lipid levels remained unchanged relative to those in od/od rats fed the vitamin C-replete diet. The serum very low density lipoprotein and high density lipoprotein (HDL) cholesterol levels were lower in od/od rats fed the vitamin C-deficient diet without cholesterol, but intermediate density lipoprotein and low density lipoprotein cholesterol levels were markedly higher in the vitamin C-deficient od/od rats than in od/od rats given ascorbic acid, regardless of dietary cholesterol level. The ratio of HDL2 cholesterol to HDL3 cholesterol was also higher in the vitamin C-deficient od/od rats. The parent strain of the od/od rats (+/+) showed no change due to vitamin C deficiency. These results suggest that vitamin C deficiency delays low density lipoprotein metabolism and produces hypercholesterolemia in male od/od rats.     

Dietary grape seed tannins affect lipoproteins, lipoprotein lipases and tissue lipids in rats fed hypercholesterolemic diets

The effects of monomeric and polymeric grape seed tannins on rat plasma lipoproteins, lipoprotein lipase, hepatic lipase and aortic and hepatic lipid concentration were studied. Male Sprague-Dawley rats received either a normal diet (with no added cholesterol and no tannins), a control diet (hypercholesterolemic diet) or hypercholesterolemic diets supplemented with 2% tannin monomers or 2% polymers 3 or 9 wk. Plasma total cholesterol, triacylglycerol, LDL cholesterol and VLDL concentrations were significantly higher and the HDL cholesterol concentration lower in controls and in rats fed the diet supplemented with monomers compared with rats fed polymeric tannins at both time points. Lipoprotein lipase and hepatic lipase activities were significantly higher in control and in monomer-fed groups than in the polymer-fed group. Hepatic and aortic cholesterol and triacylglycerol concentrations were significantly higher in control rats and those fed monomers than in the polymer-fed group. Moreover, plasma HDL cholesterol and hepatic lipase activity were closely associated with low aortic cholesterol and triacylglycerol in rats fed polymeric tannins. These rats also exhibited greater fecal excretion of cholesterol and especially bile acids than the control or monomer-fed groups. Thus dietary grape seed tannins have a pronounced anti-hypercholesterolemic effect by enhancing reverse cholesterol transport and also by reducing intestinal cholesterol absorption and increasing bile acid excretion.     

Alterations in plasma lipid, lipoprotein and apolipoprotein concentrations in copper-deficient rats

In the first experiment, 32 weanling male Sprague-Dawley rats were randomly divided into two treatment groups, namely, a copper-adequate (8 mg Cu/kg diet) or a copper-deficient (0.85 mg Cu/kg diet) group. These animals were used for the plasma lipoprotein determinations. In the second experiment, 20 similar rats were assigned to the two treatments and were used for plasma and blood volume determinations. Feed and distilled water were provided ad libitum. After 7 weeks, plasma was obtained by heart puncture. Plasma lipoproteins were partitioned and purified by ultracentrifugation and agarose-column chromatography into high, low and very low density lipoprotein fractions (HDL, LDL, VLDL). The apolipoprotein profile of HDL fraction was established by polyacrylamide gel electrophoresis. The markedly reduced liver copper content of rats fed the copper-deficient diet confirmed that they were indeed copper-deficient. Significant elevations in protein and cholesterol contents of HDL and LDL fractions and in triglyceride content of LDL fraction were observed in the copper-deficient rats. In addition, the apolipoprotein E concentration of the HDL fraction was significantly increased in the copper-deficient rats. In the second experiment, the hematocrit was markedly reduced and the plasma volume was significantly increased in the rats fed the copper-deficient diet. Data derived from this study and previous studies suggest that the hypercholesterolemia associated with copper deficiency was due mainly to an impairment in the cholesterol degradation process.     

Effects of resistant potato starch on cholesterol and bile acid metabolism in the rat

This study examines the effects of two types of resistant starch (RS), raw starch from uncooked potatoes and retrograded starch in the form of cooked and cooled potatoes, on cholesterol and bile acid metabolism in rats. Groups of 8 male Wistar rats were fed a semipurified diet containing 15% cellulose, freeze-dried raw potatoes, or freeze-dried cooked potatoes for four weeks. Serum cholesterol, liver cholesterol, and fecal steroid excretion were determined. Serum cholesterol was significantly higher and liver cholesterol was significantly lower in response to the cooked potato diet compared to the cellulose or raw potato diet. Total steroid excretion was significantly higher in rats fed the cooked potato diet (26.31 mg/d) compared to those fed the cellulose or raw potato diet (14.27 mg/d and 16.81 mg/d, respectively). Daily total bile acid excretion was significantly different among the three groups, with highest excretion seen in rats fed cooked potatoes. High daily excretion of lithocholic acid and hyodeoxycholic acid was observed in rats fed cooked potatoes. These results suggest that changes in the cecal microflora and in the production, pool size, and excretion of chenodeoxycholic acid and its derivatives may be responsible for alterations in cholesterol and bile acid metabolism observed with resistant starch feeding.     

Mechanism study of chitosan on lipid metabolism in hyperlipidemic rats

It has been reported that plasma and liver cholesterol concentrations decrease when animals are fed with chitosan, but the mechanism is unclear. Four wk old male SD (Sprague-Dawley) rats were fed a commercial rat diet (cholesterol-free diet, negative control, NC), cholesterol-enriched diet containing 5% of chitosan (CH) or cholesterol-enriched diet containing 5% of cellulose (CE) and 5% of lard for 12 weeks. We would investigated the effects of chitosan on plasma and liver cholesterol levels, liver weight, bile acids concentrations of fecal and hepatic LDL receptor mRNA expression. The results showed that chitosan could decrease levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) in plasma (p<0.05), and TC, total triglyceride (TG) in liver (p<0.05), and increase fecal bile acids excretion (p<0.05), but the levels of TG and HDL-C in plasma was unchanged (p>0.05). In addition, the result of RT-PCR test showed that saturated fat and cholesterol fed could significantly induce the reduction of LDL receptor mRNA levels, while chitosan could increase hepatic LDL receptor mRNA levels. This study suggested that chitosan improve lipid metabolism by regulating TC and LDL-C by upregulating of hepatic LDL receptor mRNA expression, increasing the excretion of fecal bile acids.     

Effect of dietary fiber on hypercholesterolemia induced by dietary PCB or cholesterol in rats

Effects of 0.03% polychlorinated biphenyls (PCB) in the diet and various dietary fibers [konjac mannan (KM), pectin, sodium carboxymethyl cellulose (CMC) and cellulose] at a 5% level in the diet on serum and liver lipid metabolism and urinary ascorbic acid were studied. A comparison between dietary PCB and 1% cholesterol in the diet was also made. Serum albumin, protein, total and high density lipoprotein (HDL)-cholesterol, triglyceride, urinary and liver ascorbic acid, liver cholesterol and total lipids were increased in rats fed PCB. Pectin or KM depressed the elevation in serum protein, total and HDL-cholesterol, triglyceride and liver lipids due to PCB intake. Cellulose or CMC had no significant effect on these indices. Urinary ascorbic acid was not decreased by these dietary changes. Serum total cholesterol and low density lipoprotein (LDL) plus very low density lipoprotein (VLDL)-cholesterol, and liver total lipids, and cholesterol were significantly higher, and serum HDL-cholesterol and triglyceride were significantly lower in the cholesterol-fed group as compared to PCB-fed rats. Addition of KM to a cholesterol diet significantly depressed serum total cholesterol and LDL plus VLDL-cholesterol, liver cholesterol and total lipids. It seems likely that cholesterol metabolism is quite different during dietary PCB and cholesterol feeding.     

5种植物油对大鼠血脂和脂质过氧化的影响

观察 5种植物油在高脂血症形成过程中对大鼠血脂和脂质过氧化的影响。在高脂饲料中分别加入6 %的猪油、松籽油、紫苏油、黑加仑油、琉璃苣油和月见草油喂饲 Wistar雄性成年大鼠 3周 ,5种植物油组大鼠血清甘油三酯 (TG)、总胆固醇 (TC)、低密度脂蛋白胆固醇 (L DL- C)、L DL- C与高密度脂蛋白胆固醇(HDL - C)比值 (L DL - C/ HDL - C)的增加值和 HDL - C/ TC、卵磷脂胆固醇酰基转移酶 (L CAT)活性的下降均不同程度地低于单纯食猪油的高脂对照组。紫苏油、黑加仑油、琉璃苣油和月见草油可提高血清 HDL- C、高密度脂蛋白亚组分 胆固醇 (HDL2 - C)及 HDL2 - C与高密度脂蛋白亚组分 胆固醇 (HDL3- C)比值 (HDL2 - C/ HDL3- C)。紫苏油、黑加仑油和月见草油组大鼠肝脏过氧化脂质 (L PO)含量高于松籽油、琉璃苣油和猪油组。结果表明 5种植物油均具有一定的调节血脂作用 ,松籽油和琉璃苣油的组织脂质过氧化物相对较低     

Relative effects of dietary oleic- and linoleic-rich oils on plasma lipoprotein composition in rats

Plasma lipoprotein composition and hepatic lipid content were investigated in male Sprague-Dawley rats (104 +/- 2 g) fed diets containing 12% olive oil [OO, 70% 18:1(n-9)], 12% high oleic safflower oil [SO, 70% 18:(ln-9)] or 12% high linoleic safflower oil [SL, 73% 18:2(n-6)] for periods of up to 10 wk. Fasting plasma triglycerides were significantly higher after feeding oleic-rich diets than after feeding SL for 3, 5 and 6 wk. At 6 wk VLDL triglycerides were two- to threefold higher in rats fed OO or SO than in those fed SL, but by 10 wk both plasma and VLDL triglycerides were similar. A greater proportion of HDL2 (diameter 8.0-12.1 nm), a lower proportion of HDL1 (diameter 12.2-17.0 nm) and lower HDL apo E content occurred in rats fed OO and SO than in those fed SL at both 6 and 10 wk. LDL and HDL protein and cholesterol concentrations were not different with feeding SO or SL. After 10 wk of feeding the experimental diets, rats fed OO had significantly lower HDL protein, cholesterol and apo E concentrations and significantly higher hepatic triglyceride content compared to rats fed SO or SL, P less than 0.05. These data suggest that HDL and hepatic lipid content are determined by some property of the dietary oil other than its oleic acid content.     

Effects of guar gum and wheat bran on lipid metabolism of rats.

The effects of guar gum and wheat bran on blood and liver lipid levels of rats were measured. In experiment 1, rats were fed ad libitum a 55% sucrose diet containing 0, 15 or 25% wheat bran for 3 weeks. Postprandial plasma triglyceride, liver triglyceride and liver cholesterol values in rats fed the sucrose diet with wheat bran were significantly lower than values for rats fed the diet without wheat bran. Neither fasting plasma triglyceride nor cholesterol values were altered by wheat bran. In experiment 2, rats were meal-fed one of four experimental diets for 3 weeks: sucrose, sucrose-cholesterol, sucrose-cholesterol-bran or sucrose-cholesterol-guar gum. Rats fed sucrose-cholesterol-guar gum diet had significantly lower fasting plasma total cholesterol, liver triglyceride and liver cholesterol values, but higher plasma high density lipoprotein (HDL) cholesterol values than those fed sucrose-cholesterol diet. These values were similar for the sucrose-cholesterol and sucrose-cholesterol-bran groups. Fasting plasma triglyceride levels were not altered by wheat bran or guar gum. These studies indicate that while guar gum lowers fasting plasma total cholesterol and raises HDL cholesterol, wheat bran does not.     

Prickly pear (Opuntia sp.) pectin reverses low density lipoprotein receptor suppression induced by a hypercholesterolemic diet in guinea pigs.

The effects of prickly pear pectin on plasma LDL metabolism were investigated by feeding guinea pigs either a diet containing 15 g/100 g lard and 0.25 g/100 g cholesterol (LC diet) or the LC diet in which cellulose was partially replaced (2.5 g/100 g) by prickly pear pectin (LC-P diet). The LC-P diet lowered plasma LDL cholesterol concentrations by 33% (P < 0.001). Low density lipoprotein composition was modified by intake of prickly pear pectin; the relative percentages of free and esterified cholesterol were lower and triglycerides were higher in LDL from animals fed the LC-P diet (P < 0.05). Intake of prickly pear pectin did not affect hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity; however, hepatic free and esterified cholesterol concentrations were lowered by 46 and 64%, respectively. Hepatic apolipoprotein B/E receptor expression (Bmax) was 60% higher in animals fed the LC-P diet (P < 0.01). Similar to the in vitro data, receptor-mediated LDL fractional catabolic rates were 190% higher in animals fed the LC-P diet (P < 0.05), whereas apolipoprotein LDL flux rates were not affected. Apolipoprotein LDL pool size and fractional catabolic rates exhibited a significant correlation (r = -0.52, P < 0.01). These data indicate that an increase in apolipoprotein B/E receptor expression is a major metabolic response by which intake of prickly pear pectin decreases plasma LDL concentrations.     

Effect of diet during pregnancy and lactation on the activity of HMG-CoA reductase in the developing rat

Wistar rats were fed a control diet or a diet containing either cholestyramine or high fat and cholesterol throughout gestation and the first 14 d of lactation. New-born litters were cross-fostered from rats fed the control diet to rats fed either cholestyramine or high fat and cholesterol, or from rats fed cholestyramine to rats fed the control diet. Hepatic hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase activity, plasma cholesterol and triglycerides were assayed on gestation d 20 and postnatal d 8, 14, 22 and 30. Cholestyramine had no effect on maternal or fetal plasma lipid levels but increased fetal hepatic HMG-CoA reductase activity by approximately 50%. The increased reductase activity persisted on postnatal d 8 and 14. Control pups suckled by dams fed cholestyramine also had significantly increased HMG-CoA reductase activities on postnatal d 8 and 14. The high fat and cholesterol diet significantly increased maternal plasma cholesterol but had no effect on HMG-CoA reductase activity in the fetus or suckling pups. Neither cholestyramine nor high fat and cholesterol altered the rat milk cholesterol levels. The studies demonstrate that HMG-CoA reductase activity in the developing rat can be altered by factors dependent on maternal diet. They do not support a hypothesis for regulation by maternal dietary or milk cholesterol supply.     

苏子油对大鼠血脂及血液流变性的影响

报告了苏子油对大鼠血清甘油三脂（ＴＧ）、总胆固醇（ＴＣ）、高密度脂蛋白（ＨＤＬ－Ｃ）、低密度脂蛋白（ＬＤＬ－Ｃ）、红细胞变形指数、血小板聚集率及ＨＤＬ－Ｃ／ＴＣ的影响。实验共分三组，猪油组、苏子油组、基础饲料组，前二组均为高脂饲料。试验期７８天。结果显示：苏子油组血ＴＣ值在试验后３０天即显著低于猪油组（Ｐ＜０．０５）。试验期末，苏子油组的ＴＣ、ＴＧ、ＬＤＬ－Ｃ均显著低于猪油组（Ｐ＜０．０５），ＴＧ值还低于基础饲料组（Ｐ＜０．０５），而ＨＤＬ－Ｃ／ＴＣ则显著高于猪油组；ＨＤＬ－Ｃ三组差别不明显（Ｐ＞０．０５）；血小板聚集率基础饲料组和苏子油组差别无意义（Ｐ＞０．０５）；但红细胞变形指数以基础饲料组最低，苏子油组其次，猪油组最高，后两组差别无意义（Ｐ＞０．０５）。提示富含α－亚麻酸的苏子油具有良好的预防和降低血脂的作用，值得进一步研究和开发。     

Effect of dietary safflower phospholipid on plasma and liver lipids in rats fed a hypercholesterolemic diet.

The effect of safflower phospholipid (SP) on plasma and liver lipids in rats fed a hypercholesterolemic diet was examined. Triglyceride mixture (SPO) of safflower oil and palm oil (8:2) containing almost comparable amounts of linoleic acid to safflower phospholipid was used as a control diet. Similarly, the effect of paste safflower phospholipid (PSP) which contains approximately 45% of neutral lipid was also compared to safflower oil (SO). Concentrations of total cholesterol in plasma and liver of rats fed the SP diet were markedly decreased in comparison with those of the other diets, but a slight reduction of total cholesterol in plasma and liver was observed in rats fed PSP diet. SP and PSP induced a reduction in the plasma level of low density lipoprotein (LDL) cholesterol as well as an increase in the level of high density lipoprotein (HDL) cholesterol. The activity of plasma lecithin-cholesterol acyltransferase (LCAT) was greatly increased in rats fed SP diet. These results suggest that the safflower phospholipids suppress the elevation of plasma and liver cholesterol and that this effect may depend on the phospholipid content in dietary lipid.     

Effect of ethanol on lipoprotein synthesis and fecal sterol excretion

The effect of variable doses of ethanol on plasma lipoprotein composition, lipoprotein synthesis and fecal sterol excretion was examined in male, atherosclerosis susceptible squirrel monkeys. Primates were divided into three groups: 1) Controls fed isocaloric liquid diet; 2) Low Ethanol monkeys given liquid diet with vodka substituted isocalorically for carbohydrate at 12% of calories; and 3) High Ethanol animals fed diet plus vodka at 24% of calories. Circulating high density lipoprotein (HDL) free cholesterol and phospholipid, very low density-low density lipoprotein (VLDL-LDL) total cholesterol, and total plasma cholesterol and triglyceride were significantly elevated in High Ethanol primates compared to the other treatments. However, the percent distribution of cholesterol among the lipoprotein fractions was identical for the three groups. There were no significant differences in serum glutamate oxalo-acetate transaminase. High Ethanol primates also had significantly greater HDL free cholesterol specific activity following intravenous injection of ³H mevalonolactone compared to the other groups while radioactive VLDL-LDL free cholesterol was elevated in both High and Low Ethanol animals. Although, total fecal bile acid mass was significantly greater in both alcohol treatment groups compared to Controls, fecal neutral sterol specific activity was only higher in monkeys fed the high ethanol diet. This study provides evidence that ethanol at 24% of calories: 1) raises HDL cholesterol levels by enhancing lipoprotein synthesis; 2) increases the fecal output of newly synthesized cholesterol without causing liver dysfunction; and 3) maintains a constant relative distribution of cholesterol among lipoprotein classes.