共查询到20条相似文献,搜索用时 15 毫秒
1.
This study investigated the effect of two partially hydrolyzed guar gums (PHGG) on fatty acid and sterol excretion. PHGG were obtained by chemical hydrolysis of guar gum (GG) with H2O:EtOH (1:1) at 100 °C for 1 h (PHGG1) or 2 h (PHGG2). The viscosity of the PHGG in a 1 % (w/v) aqueous solution corresponded to that of a pseudoplastic fluid and was higher for PHGG1 than PHGG2. Guinea pigs (n = 8 per group) were fed high fat diets (17/100 g) that contained 12/100 g of cellulose, PHGG1, or PHGG2 for 4 weeks. Despite the differences in viscosity, the two PHGG exerted similar physiological effects. Compared to the control cellulose group, the body weight gain was lower in animals fed PHGG, although no effect on food consumption was observed. PHGG increased the excretion of fatty acids and neutral sterols, but not bile acids. Consumption of PHGG did not alter the fecal fatty acid profile, while intestinal bioconversion of sterols tended to increase in response to PHGG2. A reduction in the viscosity within the range tested did not correlate with losses in the hypocholesterolemic capacity of PHGG as both were effective in reducing plasma cholesterol. Thus, we conclude that the chemical hydrolysis of guar gum renders the gum suitable for inclusion in food products without significantly altering its beneficial health effects. 相似文献
2.
Marie-Laure Favier Pierre-Etienne Bost Christian Demigné Christian Rémésy 《Lipids》1998,33(8):765-771
A viscous hydrocolloid (guar gum, GG; 2.5% of the diet) or a steroid sequestrant (cholestyramine; 0.5% of the diet) was included
in semipurified diets containing 0.2% cholesterol to compare the cholesterol-lowering effects of each agent in rats. In the
present model, GG significantly lowered plasma cholesterol (−25%), especially in the density <1.040 kg/L fraction, whereas
cholestyramine was less potent. Bile acid fecal excretion significantly increased only in rats fed cholestyramine, similar
to the cecal bile acid pool; the biliary bile acid secretion was accelerated by GG, but not their fecal excretion, whereas
GG effectively enhanced neutral sterol excretion. As a result, the total steroid balance (+13 μmol/d in the control) was shifted
toward negative values in rats fed the GG or cholestyramine diets (−27 or −50 μmol/d, respectively). Both agents induced liver
3-hydroxy-3-methylglutaryl-CoA reductase, but cholestyramine was more potent than GG in this respect. The present data suggest
that, at a relative low dose in the diet, GG may be more effective than cholestyramine in lowering plasma cholesterol by impairing
cholesterol absorption and by accelerating the small intestine/liver cycling of bile acids, which is interestingly, accompanied
by reduction of bile acid concentration in the large intestine. 相似文献
3.
Effectiveness of resistant starch,compared to guar gum,in depressing plasma cholesterol and enhancing fecal steroid excretion 总被引:2,自引:0,他引:2
Marie-Anne Levrat Corinne Moundras Hassan Younes Christine Morand Christian Demigné Christian Rémésy 《Lipids》1996,31(10):1069-1075
Amylase-resistant starch (RS) represents a substrate that can be administered in substantial amounts in the diet, in contrast
to gel-forming polysaccharides, such as guar gum (GG). The aim of this work was thus to compare the effects of GG and RS on
cholesterol metabolism in rats adapted to 0.4% cholesterol diets, using dietary GG or RS levels (8 or 20%, respectively) that
led to a similar development of fermentations, as assessed by the degree of enlargement of the cecum. The RS diet elicited
a marked rise in the cecal pool of short-chain fatty acids, especially acetic and butyric acid, whereas the GG diet favored
high-propionic acid fermentations. Both polysaccharides markedly altered the cholesterol excretion, from 50% of ingested cholesterol
in controls, up to about 70% in rats adapted to the RS or GG diets. With these diets, the fecal excretion of bile acids was
enhanced (67 and 144% with the RS and GG diets, respectively). RS and GG diets were effective in lowering plasma cholesterol
(about −40%) and triglycerides (−36%). There was practically no effect of the diets on cholesterol in d>1.040 lipoproteins
(high density lipoproteins), whereas RS (and to a larger extent, GG) were very effective to depress cholesterol in d<1.040
lipoproteins (especially in triglyceride-rich lipoproteins). Fermentable polysaccharides counteracted the accumulation of
cholesterol in the liver, especially cholesterol esters. In parallel, liver acyl CoA:cholesterol acyltransferase was depressed
in rats fed the RS or GG diets, whereas only the GG diet counteracted the downregulation of 3-hydroxy-3-methylglutaryl-CoA
by cholesterol. These data suggest that RS may be practically as effective as a gel-forming gum, such as GG, on steroid excretion
and on cholesterol metabolism. 相似文献
4.
Cholesterol-lowering effects of guar gum: Changes in bile acid pools and intestinal reabsorption 总被引:1,自引:0,他引:1
Soluble fibers such as guar gum (GG) may exert cholesterol-lowering effects. It is generally accepted that bile acid (BA)
reabsorption in portal blood is reduced, thus limiting the capacity of BA to down-regulate liver cholesterol 7α-hydroxylase,
the rate-limiting enzyme of BA synthesis. In the present work, rats were adapted to fiber-free (FF) or 5% GG diets (supplemented
or not with 0.25% cholesterol), to investigate various aspects of enterohepatic BA cycling. GG in the diet at a level of 5%
elicited a significant lowering of plasma cholesterol during the absorptive period, in cholesterol-free (−13%) or 0.25% cholesterol
(−20%) diet conditions. In rats adapted to the GG diets, the small intestinal and cecal BA pools and the ileal vein-artery
difference for BA were markedly enhanced; reabsorption in the cecal vein was also enhanced in these rats. [14C]Taurocholate absorption, determined in perfused ileal segments, was not significantly different in rats adapted to the FF
or GG diet, suggesting that a greater flux of BA in the ileum might support a greater ileal BA reabsorption in rats adapted
to the GG diet. In contrast, capacities for [14C]cholate absorption from the cecum at pH 6.5 were higher in rats adapted to the GG diet than to the FF diet. Acidification
of the bulk medium in isolated cecum (from pH 7.1 down to pH 6.5 or 5.8) or addition of 100 mM volatile fatty acids was also
found to stimulate cecal [14C]cholate absorption. These factors could contribute to accelerated cecal BA absorption in rats fed the GG diet. The effects
of GG on steroid fecal excretion thus appear to accompany a greater intestinal BA absorption and portal flux to the liver.
These results suggest that some mechanisms invoked to explain cholesterol-lowering effect of fibers should be reconsidered. 相似文献
5.
Polyoxyethalated cholesterol (POEC) is a water soluble derivative of cholesterol which decreases cholesterol absorption in
rats without affecting body weight, fatty acid excretion, or intestinal histology. In the present study rat feces were analyzed
for cholic, deoxycholic, chenodeoxycholic, muricholic and lithocholic acid following 3 months of feeding a standard or a 2%
enriched cholesterol diet with or without 1.5% POEC. In rats maintained on the cholesterol free diet, POEC increased total
bile acids (mg/day) by 50% from 14±3 to 21±3 (mean ±SEM) but only the increase in chenodeoxycholic acid was significant (P<0.05).
The corresponding POEC effect in the 2% cholesterol diet was 31% (70±8 to 93±3, P<0.01). Fecal nitrogen and serum cholesterol
did not vary among groups. Comparing these data with neutral steroid excretion previously determined showed that POEC in the
cholesterolfree diet increased the negative cholesterol balance more than three-fold (34±7vs 118±13 P<0.01). In rats fed 2% cholesterol, POEC caused a negative cholesterol balance of 222±8 compared to the control of
27±52 (P<0.01). The data indicate that POEC exerts complex effects in the intestinal tract which increase both bile acid and
cholesterol excretion. 相似文献
6.
Elke A. Trautwein Dörte Rieckhoff Angelika Kunath-Rau Helmut F. Erbersdobler 《Lipids》1998,33(6):573-582
Different soluble dietary fibers known to alter cholesterol metabolism were fed to golden Syrian hamsters, and their specific
impact on lipoproteins, biliary bile acid profile, and fecal sterol excretion was evaluated. Semipurified diets containing
20% fat; 0.12% cholesterol; and 8% of psyllium (PSY); high (hePE) and low (lePE) esterified pectin; or high (hvGG) and low
(lvGG) viscous guar gum were fed for 5 wk. Compared to control, PSY caused a significant reduction in plasma cholesterol (2.9±0.5
vs. 5.5±0.5 mmol/L), whereas hePE, lePE, hvGG, or lvGG had no apparent effect on plasma lipids. Hepatic total and esterified
cholesterol were substantially decreased with PSY, pectin and guar gum, whereby PSY produced the most pronounced effect. Distinctive
changes existed in the bile acid profile related to the different fibers. In contrast to pectin and guar gum, PSY caused a
significant increase in the cholate:chenodeoxycholate and the glycine:taurine conjugation ratio. Pectin and guar gum did not
alter daily fecal neutral sterol excretion while PSY caused a 90% increase due to a higher fecal output. Daily fecal bile
acid excretion and total fecal bile acid concentration were significantly increased by PSY, whereas hePE, lePE, hvGG, and
lvGG revealed no or only minor effects. Taken together, the disparate hypocholesterolemic effects of PSY, pectin, and guar
gum on cholesterol and bile acid metabolism in the hamster are possibly related to different physicochemical properties, e.g.,
viscosity and susceptibility to fermentation, affecting the fiber-mediated action in the intestine. 相似文献
7.
Contrasting effects of water-soluble and water-insoluble dietary fibers on bile acid conjugation and taurine metabolism in the rat 总被引:2,自引:0,他引:2
The effect of the type of dietary fiber on the bile acid and taurine metabolism was examined in rats. Diets containing 10%
of various water-soluble fibers (citrus pectin, konjak mannan, guar gum) as compared to a fiber-free diet increased biliary
excretion of total bile acids. In contrast, water-insoluble dietary fibers (cellulose, corn bran, chitin; 10% in the diets)
as well as cholestyramine (5% in the diet) considerably, decreased bile acid excretion. Water-soluble dietary fibermediated
increases in bile acid excretion were totally attributable to increases in glycine-conjugates. Thus, these fibers greatly
increased by the bile acid glycine-to-taurine ratio (G/T). Excretio of glycine conjugates decreased more than that of taurine
conjugates in rats fed various water-insoluble dietary fibers. As a results, G/T in rats fed water-insoluble fibers was significantly
lowered as compared to G/T in animals fed a fiber-free diet. Cholestyramine did not affect the G/T ratio of bile acids. Fecal
bile acid excretion and the activities of hepatic cholesterol 7α-hydroxylase (EC 1.14.13.17) in rats fed various water-soluble
dietary fibers approximately doubled as compared to the respective values for rats fed a fiber-free diet. Whereas cholestyramine
greatly increased these parameters, water-insoluble fibers did not significantly affect them. Various water-soluble fibers
decreased hepatic concentration and urinary excretion of taurine as well as the activity of hepatic cysteine dioxygenase (EC
1.13.11.20). In contrast, water-insoluble fibers considerably increased hepatic taurine concentrations and enzyme activities.
The parameters for taurine metabolism were unaffected by cholestyramine. It was suggested that the types of dietary fiber
affected hepatic taurine synthesis and thus modified bile acid glycine/taurine ratios. 相似文献
8.
Resistant starch is more effective than cholestyramine as a lipid-lowering agent in the rat 总被引:4,自引:0,他引:4
Amylase-resistant starch (RS) represents a substrate for the bacterial flora of the colon, and the question arises as whether
RS shares with soluble fibers common mechanisms for their lipid-lowering effects. It is uncertain whether a cholesterol-lowering
effect depends basically on an enhanced rate of steroid excretion or whether colonic fermentations also play a role in this
effect. In the present study, the effect of RS (25% raw potato starch), of a steroid sequestrant (0.8% cholestyramine), or
both were compared on bile acid excretion and lipid metabolism in rats fed semipurified diets. RS diets led to a marked rise
in cecal size and the cecal pool of short-chain fatty acids (SCFA), as well as SCFA absorption; cholestyramine did not noticeably
affect cecal fermentation. Whereas cholestyramine was particularly effective at enhancing bile acid excretion, RS was more
effective in lowering plasma cholesterol (−32%) and triglycerides (−29%). The activity of 3-hydroxy-3-methylglutaryl-CoA reductase
was increased fivefold by cholestyramine and twofold by RS. This induction in rats fed RS diets was concomittant to a depressed
fatty acid synthase activity. In rats fed the RS diet, there was a lower concentration of cholesterol in all lipoprotein fractions,
especially the (d=1.040−1.080) fraction high-density lipoprotein (HDL1), while those fed cholestyramine had only a significant reduction of HDL1 cholesterol. In contrast to cholestyramine, RS also depressed the concentration of triglycerides in the triglyceride-rich
lipoprotein fraction. There was no noticeable synergy between the effects of RS and cholestyramine when both were present
in the diet. This suggests that the cholesterol-lowering effect of RS is not limited to its capacity to enhance bile acids
excretion. The difference between RS and cholestyramine could relate to the capacity of fermentation end-products to counteract
the upregulation of cholesterol and bile acid biosynthesis. Thus, in the absence of fermentation in the large intestine, a
high rate of bile acids excretion is not always sufficient to elicit a cholesterol-lowering effect. 相似文献
9.
The effect of chitosan feeding (for 21 days) on intestinal bile acids was studied in male rats. Serum cholesterol levels in
rats fed a commercial diet low in cholesterol were decreased by chitosan supplementation. Chitosan inhibited the transformation
of cholesterol to coprostanol without causing a qualitative change in fecal excretion of these neutral sterols. Increased
fiber consumption did not increase fecal excretion of bile acids, but caused a marked change in fecal bile acid composition.
Litcholic acid increased sigificantly, deoxycholic acid increased to a leasser extent, whereas hyodeoxycholic acid and the
6β-isomer and 5-epimeric 3α-hydroxy-6-keto-cholanoic acid(s) decreased. The pH in the cecum and colon became elevated by chitosan
feeding which affected the conversion of primary bile acids to secondary bile acids in the large intestine. In the cecum,
chitosan feeding increased the concentration of α-,β-, and ω-muricholic acids, and lithocholic acid. However, the levels of
hyodeoxycholic acid and its 6β-isomer, of monohydroxy-monoketo-cholanoic acids, and of 3α, 6ξ, 7ξ-trihydroxy-cholanoic acid
decreased. The data suggest that chitosan feeding affects the metabolism of intestinal bile acids in rats. 相似文献
10.
David Kritchevskya Shirley A. Tepper Subramanian Satchithanandam Marie M. Cassidy George V. Vahouny 《Lipids》1988,23(4):318-321
Rats (6 per group) were fed semipurified diets containing either particulate fibers (alfalfa, 10%; cellulose, 10%; bran, 10%),
a soluble ionic fiber (pectin 5%), soluble, nonionic fibers (guar gum, 5%; Metamucil, 10%), a mixed fiber preparation (Fibyrax,
10%, or an insoluble, ionic bile acid-binding resin (cholestyramine, 2%). The control group was fed the unsupplemented diet.
The feeding period, during which diet and water were provided ad libitum, was 28 days.
Compared with the control group, serum total cholesterol levels were increased by more than 10% in rats fed alfalfa and decreased
by more than 10% in rats fed cellulose, guar gum, Fibyrax and cholestyramine. There were no significant differences in percentage
of plasma HDL cholesterol. Serum triglycerides were elevated in the groups fed alfalfa, pectin, guar gum or Fibyrax and reduced
in the group fed Metamucil. Plasma phospholipids were elevated in rats fed alfalfa or bran, unaffected in rats fed pectin
or Metamucil and reduced in the other groups. Liver total cholesterol was elevated in all groups but those fed wheat bran
and cholestyramine. The percentage of liver cholesterol present as ester was elevated in every group except that fed cholestyramine.
Liver triglycerides were reduced in rats fed guar gum or Metamucil and elevated in those fed alfalfa. Liver phospho-lipids
were lowered in the group fed cellulose.
Liver phospholipids were fractionated by thin layer chromatography to give phosphatidylcholine (PC), phosphatidylethanolamine
(PE), sphingomyelin (Sph), lysophosphatidylcholine (LPC) and phosphatidylinositol plus phosphatidylserine (PI+PS). PC was
elevated in all test groups (7–25%); PE levels ranged from 14% below to 0.3% above controls; Sph levels were sharply lower
(20–53%) in all groups. LPC and PI+PS levels were close to the control value in all test groups.
The results demonstrate that different dietary fibers can affect liver phospholipid composition. In view of the critical roles
of phospholipids in many biological reactions, it will be interesting to survey the influence of dietary fiber on phospholipid
spectra of other tissues.
Deceased. 相似文献
11.
Plasma cholesterol, arachidonic acid (AA, 20∶4n−6), and docosahexaenoic acid (DHA, 22∶6n−3) are higher in breast-fed infants
than in infants fed formula without cholesterol, AA, or DHA. This study investigated differences in plasma, hepatic, and bile
lipids and phospholipid fatty acids, and expression of hepatic proteins involved in sterol metabolism that result from feeding
formula with cholesterol with egg phospholipid to provide AA and DHA. For this study, three groups of piglets were evaluated:
piglets fed formula with 0.65 mmol/L cholesterol, the same formula with 0.8% AA and 0.2% DHA from egg phospholipid, and piglets
fed sow milk. Piglets fed the formula with phospholipid AA and DHA had higher plasma high density lipoprotein, but not apoprotein
(apo) B cholesterol or triglyceride; higher bile acid and phospholipid concentrations in bile; and higher liver and bile phospholipid
AA and DHA than piglets fed formula without AA and DHA (P<0.05). Hydroxy methylglutaryl (HMG)-CoA reductase and 7-α-hydroxylase, the rate-limiting enzymes of cholesterol and bile
acid synthesis, respectively, and low density lipoprotein receptor mRNA levels were not different between piglets fed formula
without and with phospholipid AA and DHA, but HMG-CoA reductase and 7α-hydroxylase mRNA were higher, and plasma apo B containing
lipoprotein cholesterol was lower in all piglets fed formula than in piglets fed milk. These studies show that supplementing
formula with AA and DHA from egg phospholipid alters bile metabolism by increasing the bile AA and DHA, and bile acid and
phospholipid. 相似文献
12.
N,N-dimethyl-n-octadecylamine borane 1 at 8 mg/kg/day, tetrakis-u-(trimethylamine boranecarboxylato)-bis(trimethyl-carboxyborane)-dicopper(II) 2 at 2.5 mg/kg/day and trimethylamine-carboxyborane 3 at 8 mg/kg/day were evaluated for their effects on bile lipids, bile acids, small intestinal absorption of cholesterol and cholic acid and liver and small intestinal enzyme activities involved in lipid metabolism. The agent administered orally elevated rat bile excretion of lipids, e.g. cholesterol and phospholipids, and compounds 2 and 3 increased the bile flow rate. These agents altered the composition of the bile acids, but there was no significant increase in lithocholic acid which is most lithogenic agent in rats. The three agents did decrease cholesterol absorption from isolated in situ intestinal duodenum loops in the presence of drug. Hepatic and small intestinal mucosa enzyme activities, e.g. ATP-dependent citrate lyase, acyl CoA cholesterol acyl transferase, cholsterol-7-alpha -hydroxylase, sn glycerol-3-phosphate acyl transferase, phosphatidylate phosphohydrolase, and lipoprotein lipase, were reduced. However, the boron derivatives 1 and 3 decreased hepatic HMG-CoA reductase activity, the regulatory enzyme for cholesterol synthesis, but the compounds had no effects on small intestinal mucosa HMG-CoA reductase activity. There was no evidence of hepatic cell damage afforded by the drugs based on clinical chemistry values which would induce alterations in bile acid concentrations after treatment of the rat. 相似文献
13.
Yasuharu Imai Sumio Kawata Masami Inada Shio Miyoshi Yuzo Minami Yuji Matsuzawa Kiyohisa Uchida Seiichiro Tarui 《Lipids》1987,22(7):513-516
Effects of cholestyramine on biliary secretion of cholesterol, phospholipids and bile acids and fecal excretion of sterols
and bile acids were examined in Wistar male rats. Six rats were fed a basal diet, and the other six were fed a basal diet
supplemented with 5% cholestyramine for eight days. Bile flow and biliary secretion of bile acids and phospholipids (per hour
per rat) decreased with cholestyramine treatment, while biliary cholesterol secretion (per hour per rat) remained unchanged.
In the biliary bile acid composition, a marked increase of chenodeoxycholic acid with a concomitant decrease of β-muricholic
acid was observed in cholestyramine-treated rats. Fecal excretion of total sterols and bile acids increased about three-and
four-fold, respectively, after cholestyramine treatment. The increase of fecal bile acids derived from cholic acid was more
predominant than that derived from chenodeoxylcholic acid, resulting in an increase of the cholic acid group/chenodeoxycholic
acid group ratio. 相似文献
14.
Shirouchi B Kawamura S Matsuoka R Baba S Nagata K Shiratake S Tomoyori H Imaizumi K Sato M 《Lipids》2011,46(8):789-793
Guar gum has a well-recognized hypolipidemic effect. This effect is thought to be due to the physicochemical properties of
guar gum, which may cause changes in adsorption of lipids or the viscosity of the intestinal contents. Guar gum is a non-specific
absorption inhibitor of any type of lipid-soluble compound. Permanent lymph duct cannulation was performed on rats to investigate
the effects of dietary guar gum on lymph flow and lipid transport. Rats fed a 5% guar gum diet were compared with those fed
a 5% cellulose diet, and lymph was collected after feeding. The water-holding capacity (WHC), settling volume in water (SV),
and viscosity of guar gum were compared with those of cellulose. Rats fed with the guar gum diet had significantly lower lymph
flow and lymphatic lipid transport than did rats fed with the cellulose diet. The WHC, SV, and viscosity of guar gum were
significantly higher than those of cellulose. We propose that dietary guar gum reduces lymph flow and thereby diminishes lipid
transport by means of its physicochemical properties related to water behavior in the intestine. 相似文献
15.
Bengt E. Gustafsson Bo Angelin Ingemar Björkhem Kurt Einarsson Jan-Åke Gustafsson 《Lipids》1981,16(4):228-233
The aim of this investigation was to study the influence of chenodeoxycholic acid administration on cholesterol and bile acid
synthesis in germ-free rats. Seven rats were fed a basal diet and 2 groups of 4 rats received the same diet supplemented with
0.4 and 1% chenodeoxycholic acid, respectively. After 6 weeks, feces were collected in one 3- and one 4-day pool for analysis
of cholesterol and bile acids. When the sampling period was finished, the rats were killed and the liver microsomal fractions
isolated. The activities of HMG CoA reductase and cholesterol 7α-hydroxylase were determined, the 7α-hydroxylase by a mass
fragmentographic method. The 2 dominating bile acids in the untreated rats were cholic acid and β-muricholic acid. During
treatment with chenodeoxycholic acid, 60–70% of this bile acid was converted into α- and β-muricholic acid, indicating a high
activity of the 6β-hydroxylase. The excretion of cholic acid was almost completely inhibited and the 7α-hydroxylase activity
was decreased ca 75% in the rats fed 1% chenodeoxycholic acid. The activity of the hepatic HMG CoA reductase was unchanged.
The fecal excretion of cholesterol increased 2–3 times. An accumulation of cholesterol was seen in the rats treated with 1%
chenodeoxycholic acid, which was probably a result of the decreased catabolism of cholesterol to bile acids. 相似文献
16.
Rats were fed semipurified diets containing olive oil or partially hydrogenated corn oil at the 5 or 20% level for ca. 30
days. These fat diets contained the same amount of octadecenoate but differed in the geometry with respect to each fat level.
Contents oft-18∶1 were 26% and 41% of total fatty acids, respectively. The linoleic acid content was also made equivalent (3.8 energy
%). After feeding on cholesterol-free diets, rats ontrans fat, compared to those oncis fat, showed: (a) no changes in serum cholesterol and apolipoprotein levels, (b) no effects on the bile flow and concentrations
of biliary cholesterol or bile acids, (c) a trend toward increased fecal excretion of neutral and acidic steroids, (d) a lesser
extent of transformation of cholesterol to coprostanol in the gut, and (e) no changes in the composition of biliary and fecal
bile acids. Observations (c) and (d) were more marked with a hightrans fat regimen. These observations, except for serum apolipoproteins and fecal steroid excretion, were practically reproducible
even when rats were fed cholesterol-enriched diets.
A preliminary part of this study was presented at the 74th annual AOCS meeting, Chicago, 1983. 相似文献
17.
Distribution and biliary and fecal excretion of bile acids were examined in Wistar strain male rats of about 300 g body weight.
The pool size of the rats on ordinary diet was 40 mg/rat, biliary secretion was 14 mg/hr, and fecal excretion was 10 mg/day.
Bile acids were mainly located in the small and large intestinal contents, 87% and 10%, respectively; but a portion was found
in the intestinal wall and the liver. Rats fed 2% cholesterol-supplemented diet for a week showed similar values for pool
size and biliary secretion with the rats on ordinary diet, but higher values for fecal excretion and distribution ratio in
the large intestinal contents. Cholic acid was a major component in the bile, small intestinal wall, small intestinal content
and liver, while the bile acid composition ratios were roughly similar to each other, although a relatively large amount of
α-muricholic acid was found in the intentinal wall and liver. Both the wall and content compositions of the large intestine
were similar to that of the feces, in which lithocholic, deoxycholic, α- and β-muricholic acids were the main components,
although the ratios of α- and β-muricholic acids in the large intestinal wall were larger than those in the intestinal contents
or feces. The high concentrations of these bile acids may indicate a difference of transport velocity across the cell membrane,
but the mechanism is not known. 相似文献
18.
Feeding rats beans with resistant starch reduces their serum cholesterol concentration; however, the mechanism by which this
occurs is not fully understood. We examined the effects of enzyme-resistant fractions of adzuki (Vigna angularis) and tebou (Phaseolus vulgaris, var.) beans on serum cholesterol and hepatic mRNA in rats. Rats were fed a cholesterol-free diet with 50 g of cellulose
powder (CP)/kg, 50 g of an enzyme-resistant fraction of adzuki starch (AS)/kg, or 50 g of an enzyme-resistant fraction of
tebou starch (TS)/kg diet for 4 wk. There were no significant differences in body weight, liver weight, and cecum contents
among the groups, nor was there a significant difference in food intake among the groups. The levels of serum total cholesterol,
VLDL + intermediate density lipoprotein + LDL-cholesterol, and HDL cholesterol in the AS and TS groups were significantly
(P<0.05) lower than in the CP group throughout the feeding period. Total hepatic cholesterol in the CP group was significantly
(P<0.05) lower than in the AS and TS groups, fecal cholesterol excretion in the TS group was significantly (P<0.05) greater than in the CP and AS groups, and the fecal total bile acid concentrations in the AS and TS groups were significantly
(P<0.05) higher than in the CP group. Cecal acetate, propionate, and n-butyrate concentrations in the AS and TS groups were significantly (P<0.05) higher than in the CP group. The level of hepatic scavenger receptor class B1 (SR-B1) mRNA in the TS group was significantly
(P<0.05) higher than in the CP group, and the levels of hepatic cholesterol 7α-hydroxylase mRNA in the AS and TS groups were
significantly (P<0.05) higher than in the CP group. These results suggest that AS and TS have a serum cholesterol-lowering function due to
the enhanced levels of hepatic SR-B1 and cholesterol 7α-hydroxylase mRNA. 相似文献
19.
This experiment was designed to evaluate the effect of casein or ovomucin (OV) on the micellar solubility of cholesterol and
the taurocholate binding capacity in vitro. We also evaluated the effects of casein or OV on cholesterol metabolism in rats and Caco-2 cells. OV has a significantly
greater bile acid-binding capacity than that of casein in vitro. Micellar cholesterol solubility in vitro was significantly lower in the presence of OV compared to casein. The cholesterol micelles containing OV significantly suppressed
cholesterol uptake by Caco-2 cells compared to the cholesterol micelles containing casein. Consistent with these in vitro findings, OV-feeding significantly increased the fecal excretion of bile acids or cholesterol compared with casein-feeding.
Serum total cholesterol was significantly lower in rats fed OV than in those fed casein. The concentrations of total lipids
in liver were significantly lower in the OV-fed group compared with the casein group. These results suggest that the suppression
of cholesterol absorption by direct interaction between cholesterol mixed micelles and OV in the jejunal epithelia is part
of the mechanism underlying the hypocholesterolemic action of OV. OV may also inhibit the reabsorption of bile acids in the
ileum, thus lowering the serum cholesterol level. 相似文献
20.
This experiment was designed to evaluate the effects of dietary red wine phenolic compounds (WP) and cholesterol on lipid
oxidation and transport in rats. For 5 wk, weanling rats were fed polyunsaturated fat diets (n−6/n−3=6.4) supplemented or
not supplemented with either 3 g/kg diet of cholesterol, 5 g/kg diet of WP, or both. The concentrations of triacylglycerols
(TAG, P<0.01) and cholesterol (P<0.0002) were reduced in fasting plasma of rats fed cholesterol despite the cholesterol enrichment of very low density lipoprotein
+ low density lipoprotein (VLDL+LDL). The response was due to the much lower plasma concentration of high density lipoprotein
(HDL) (−35%, P<0.0001). In contrast, TAG and cholesteryl ester (CE) accumulated in liver (+120 and +450%, respectively, P<0.0001). However, the cholesterol content of liver microsomes was not affected. Dietary cholesterol altered the distribution
of fatty acids mainly by reducing the ratio of arachidonic acid to linoleic acid (P<0.0001) in plasma VLDL+LDL (−35%) and HDL (−42%) and in liver TAG (−42%), CE (−78%), and phospholipids (−28%). Dietary WP
had little or no effect on these variables. On the other hand, dietary cholesterol lowered the α-tocopherol concentration
in VLDL+LDL (−40%, P<0.003) and in microsomes (−60%, P<0.0001). In contrast, dietary WP increased the concentration in microsomes (+21%, P<0.0001), but had no effect on the concentration in VLDL+LDL. Cholesterol feeding decreased (P<0.006) whereas WP feeding increased (P<0.0001) the resistance of VLDL+LDL to copper-induced oxidation. The production of conjugated dienes after 25 h of oxidation
ranged between 650 (WP without cholesterol) and 2,560 (cholesterol without WP) μmol/g VLDL+LDL protein. These findings show
that dietary WP were absorbed at sufficient levels to contribute to the protection of polyunsaturated fatty acids in plasma
and membranes. They could also reduce the consumption of α-tocopherol and endogenous antioxidants. The responses suggest that,
in humans, these substances may be beneficial by reducing the deleterious effects of a dietary overload of cholesterol. 相似文献