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1.
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
2.
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
3.
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
4.
The effects of cholestyramine, a bile acid binding polymer, on the lipid and energy metabolism of chicks given dietary medium-chain
triacylglycerol (MCT) or long-chain triacylglycerol (LCT) were investigated. Chicks (from 8 to 17 days of age) were fed diets
containing MCT or LCT at 200 g oil/kg diet with or without 2% cholestyramine under equalized feeding conditions. An adjusted
LCT diet was formulated in order to supply another group with daily nutrients and dietary metabolizable energy (ME) equal
to MCT groups, except for corn starch. ME intakes of chicks given MCT or LCT diets were reduced by cholestyramine; consequently,
fat and energy retention was reduced, though the reduction was more drastic in chicks fed LCT. This was caused by a change
in amounts of the fecal excretion of fat and bile acids. Cholestyramine enhanced the excretion of octanoic acid (8∶0) in the
feces, which suggests that bile acids are needed for 8∶0 absorption. Cholestyramine affects the utilization of dietary MCT
and LCT by lowering fat and energy retention in chicks. However, the effect of cholestyramine on MCT utilization was smaller
than its effect on utilization of LCT. 相似文献
5.
Effect of dietary taurine on bile acid metabolism in guinea pigs 总被引:1,自引:0,他引:1
The effect of oral administration of taurine (200–300 mg daily) on the metabolism of bile acids was studied in male guinea
pigs which have predominantly glycine conjugated bile acids. The results were summarized as follows: (a) oral administration
of taurine for 10 days increased taurine-conjugated bile acids and the ratio of glycine-to taurine-conjugated bile acids (G:T
ratio) shifted from 3.95 to 0.19; (b) in taurine fed guinea pigs, the half-life of chenodeoxycholic acid (CDC) was about 40%
shorter than that in controls and the fractional turnover rate increased by 70%; (c) the synthetic rate (mg/day/500 g body
weight) of bile acids increased from 4.28 to 7.27 by taurine feeding; (d) hepatic cholesterol 7α-hydroxylase activity was
increased 2.4-fold by taurine feeding; (e) the total pool size of bile acids did not change significantly but the amount of
lithocholic acid in the caecum and large intestine increased by about 40%; (f) neither free cholesterol nor cholesterol ester
levels in liver and serum changed significantly. Results of this study suggest that changing the G:T ratio in the bile acid
conjugation pattern may influence the rate of hepatic bile acid synthesis.
This paper is Part IX of a series entitled “Metabolism of Bile Acids”. Part VIII: ref. 12. 相似文献
6.
Hepatic biotransformation and the effect on bile flow of 7-ketolithocholic acid (7-oxo-3α-hydroxy-5β-cholan-24-oic acid),
in comparison to ursodeoxycholic acid, were examined in rats under conditions of continuous infusion of solutions of sodium
salts of these bile acids (1.2μmol/min/100 g body wt) for 2 hr. Both bile salts elevated the bile flow rate as well as the
bile bicarbonate concentration to a similar degree. The minor difference observed was a transient (10–20 min) and subtle drop
of bile flow during the first hour in rats given 7-ketolithocholate. In ursodeoxycholate infused rats, the major bile salt
in the bile was its taurine conjugate, although excretion of tauroursodeoxycholate dropped considerably during the second
hour. In 7-ketolithocholate infused rats, the major bile salt in the bile was again, its taurine conjugate, but ursodeoxycholate
and chenodeoxycholate and their conjugates were also excreted. In contrast to ursodeoxycholate infused rats, the drop in excretion
of taurine conjugates and the increase of glycine conjugates in rats infused with 7-ketolithocholate were more rapid. In rats
infused with 7-ketolithocholate, excretion of ursodeoxycholate and its conjugates was significantly higher than the corresponding
values for chenodeoxycholate, suggesting that 7-ketolithocholate is reduced predominatly to the 7β-epimer in this species.
However, the concentration of ursodeoxycholate and its conjugates excreted into the bile in rats infused with 7-ketolithocholate
was only 10% of that of rats infused with ursodeoxycholate, yet the magnitude of choleresis and the rise in bile bicarbonate
concentration were similar in both experiments. Therefore, it is suggested that the bicarbonate-rich bile, induced by 7-ketolithocholate
infusion, is caused mainly by 7-ketolithocholate rather than by its metabolite, ursodeoxycholate. 相似文献
7.
The abnormal metabolism and distribution of plasma lipoproteins have been associated with atherosclerosis and gallstones.
To better understand the process of cholesterol excretion, a study was designed to determine whether the contribution of lipoprotein
free14C-cholesterol (as LDL or HDL) to biliary cholesterol or primary bile acids differs in two species of nonhuman primates, cebus
and cynomolgus monkeys, having opposite plasma LDL/HDL ratios. Since amino acid conjugation might influence bile acid synthesis
or secretion, the taurine and glycine conjugates of newly synthesized primary bile acids, cholic acid (CA) and chenodeoxycholic
acid (CDCA), were measured in the species capable of conjugating with taurine or glycine (cynomolgus). After total bile acid
pool washout, monkeys were infused with human LDL or HDL labeled with free14C-cholesterol, and the specific activities (SA) of biliary cholesterol and primary bile acid conjugates were determined. In
both species, regardless of the lipoprotein infused, the SA of biliary cholesterol and CA were greater than those for total
bile acids and CDCA, respectively. In cynomolgus, the SA of glycine conjugates was higher for CA than CDCA, while the SA of
taurine conjugates was greater for CDCA than CA. Under these conditions, (i) infused lipoprotein free cholesterol (as either
LDL or HDL) contributed more to biliary cholesterol than to bile acids and more to CA than to CDCA; (ii) glycine conjugated
preferentially with CA rather than CDCA, while taurine was the preferred conjugate for CDCA. Further, whereas the two primary
bile acids had similar rates of synthesis and turnover in cynomolgus, basal bile acid synthesis was much greater in cebus
and the CDCA turnover appeared disproportionately large. 相似文献
8.
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
9.
Substitution of casein for soybean protein in the diet causes high degrees of hypercholesterolemia in rabbits. When rats or
humans were fed exactly the same diets, no response of the concentration of serum cholesterol to the type of protein was observed.
The hypothesis is put forward that, in rabbits, dietary casein and peptides derived from it—because of their high degree of
phosphorylation—inhibit the binding of glycine-conjugated bile acids to insoluble calcium phosphate in the intestinal lumen.
As a result, feeding of casein causes an increase in the availability of bile acids, which leads to enhanced absorption of
bile acids and cholesterol. Eventually, the concentration of serum cholesterol will be increased. In rabbits this cascade
of events occurs because these animals have a relatively low activity of intestinal alkaline phosphatase, and a high ratio
of glycine to taurine in conjugated bile acids. Unlike glycine conjugates, taurine-conjugated bile acids do not effectively
bind to the intestinal calcium-phosphate sediment. The low activity of intestinal alkaline phosphatase in rabbits secures
the high degree of phosphorylation of casein and its peptide products in the small intestine. In contrast with rabbits, rats
and humans have high activities of intestinal alkaline phosphatase and a low glycine-to-taurine ratio in conjugated bile acids.
Thus the hypothesis presented would explain why rabbits, but not rats and humans, are susceptible to dietary casein with respect
to the concentration of serum cholesterol. The relevance of the hypothesis as to the mechanisms underlying the hypercholesterolemic
effect of some other dietary proteins is discussed. 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.
Cholesterol synthesis and degradation in normal rats fed a cholesterol-free diet with excess cystine
Feeding a diet with excess cystine to rats resulted in hypercholesterolemia. To understand the mechanism of the hypercholesterolemia’
cholesterol synthesis and degradation’ bile acid content of bile’ and fecal steroids were determined. The in vivo incorporation of tritiated water into hepatic cholesterol’ and activity of hepatic 3-hydroxy-3-methylglutaryl-CoA reductase
in rats fed a high-cystine diet were significantly higher than those in rats fed a control diet. The activity of hepatic cholesterol
7α-hydroxylase was similar between two groups. Little effect of cystine supplementation was found on fecal sterol excretion
although there were some changes in biliary excretion of cholic acid derivatives. These results indicate that hypercholesterolemia
caused by feeding of a high-cystine diet may be due to the stimulation of hepatic cholesterol synthesis. 相似文献
12.
Michihiro Sugano Takashi Ide Mitsuko Kohno Midori Watanabe Young-J. Cho Yasuo Nagata 《Lipids》1983,18(3):186-192
Male Wistar rats were fed cholesterol-free or cholesterol-enriched diets containing partially hydrogenated soybean oil with different levels of trans-fatty acids or unhydrogenated soybean oil at the 10% level. The linoleic acid content of hydrogenated fat diets was adjusted to 3.6% of the total energy. Hydrogenated fat diets contained 29% and 41% trans-acids, mainly as t-18:1. Trans-fats exerted no untoward effects on growth parameters, but increased liver weight. Dietary hydrogenated fats influenced neither the concentration nor composition of biliary steroids, irrespective of the presence or absence of cholesterol in the diet. In rats fed a cholesterol-free diet, daily fecal output of neutral and acidic steroids was enhanced by hydrogenated fats and the magnitude of augmentation was proportional to the dietary level of trans-fatty acids. The increased fecal steroid excretion corresponded to an increase in total excreta. Hydrogenated fats also tended to enhance bile acid excretion when feeding a cholesterol-enriched diet. The results suggest that dietary trans-fatty acids, in relation to cis-polyunsaturated fatty acids, provoke demonstrable change in steroid homeodynamics. 相似文献
13.
Masaharu Kamei Sumiko Ohgaki Tamotsu Kanbe Mitsuru Shimizu Shigeru Morita Isao Niiya Isao Matsui-Yuasa Shuzo Otani 《Lipids》1996,31(11):1151-1156
The effects of dietary highly hydrogenated soybean oil (HSO) upon the changes caused by dietary polychlorinated biphenyls
(PCBs) were examined in rats. Six groups of rats were fed the following diets for 30 d: a 20% soybean oil-containing diet
(control diet), a diet in which a half of soybean oil was substituted with HSO (HSO-A diet), a diet in which cellulose powder
was replaced with HSO (HSO-B diet) and these diets supplemented with 100 ppm PCBs (control+PCBs, HSO-A+PCBs and HSO-B+PCBs
diets). Hepatic concentration of PCBs and relative liver weight were markedly decreased in rats fed with the HSO-A+PCBs diet
compared with those fed with the other diets containing PCBs. Liver lipids and liver cholesterol were considerably decreased
with a reciprocal increase in fecal sterol excretion by rats fed the HSO-A+PCBs and the HSO-B+PCBs diets compared with those
fed with the control+PCBs diet. The fatty acid composition in hepatic phospholipids showed an independent increase of the
saturated fatty acid content induced by dietary HSO and PCBs. Dietary PCBs also caused decreases in the amounts of monounsaturated
and n-3 polyunsaturated fatty acids. These results suggest that dietary HSO prevents accumulation of PCBs in the liver and
promotes the excretion of lipids stimulated by PCBs, accompanied by a change in fatty acid metabolism. 相似文献
14.
Sex differences in the effect of ethionine upon rat liver metabolism prompted our investigation into possible sex differences
in the effect of ethionine upon bile acid metabolism. The bile ducts of 24 rats, 12 male and 12 female, were cannulated. After
1 hr of bile collection, 6 rats of each sex were given ethionine, 1 mg/g body wt, by feeding tube. The bile acid composition
of the bile collected during the subsequent 4 hr was analyzed by combined thin layer and gas chromatography. Ethionine induced
a reduction in bile flow (3rd and 4th hr) and in bile acid concentration (4th hr) in female rats. The amino acid had no effect
upon bile flow but did increase biliary secretion of bile acids (1st and 2nd hr) in male rats. Cholic acid accounted for the
bulk of the reduction in total bile acid secretion in the female studies. The increase in total bile acid secretion in the
male studies involved all bile acids. The effects of ethionine upon bile acid secretion were delayed in the female studies,
immediate in the male. The changes in bile acid secretion involved only the taurine conjugates in the female studies, both
taurine and glycine conjugates in the male. There are substantial sex differences in the effect of ethionine upon bile acid
metabolism in the rat. 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.
Mizuho Une Erwin H. Mosbach Bertram I. Cohen Patricia May-Donath Charles K. Mcsherry 《Lipids》1985,20(4):222-226
3α-Hydroxy-7ζ-methyl-5β-cholanoic acid (7ζ-methyl-LA) was infused intravenously into bile fistula hamsters to investigate
its metabolism and effect on the bile flow as compared with lithocholic acid. Following infusion of the labeled bile acids,
bile was collected quantitatively to allow measurement of bile flow and bile acid composition. More than 80% of radioactivity
was recovered in bile within 4 hr. 7ζ-Methyl-LA and lithocholic acid in bile were present as the taurine and glycine conjugates;
no free bile acids were detected. 7ζ-Methyl-LA was neither hydroxylated nor metabolized to any measurable extent, though lithocholic
acid was 7α-hydroxylated to chenodeoxycholic acid (30–45%).
At the infusion rate at which lithocholic acid induced a severe cholestasis (264 nmol/min), 7ζ-methyl-LA did not decrease
the bile flow. In fact, the infusion of 7ζ-methyl-LA produced a mild choleresis under conditions where endogenous bile acid
excretion was not changed appreciably compared to control infusions with albumin.
It is concluded that 7ζ-methyl-LA is not metabolized in the hamster but is conjugated with taurine and glycine, and that the
introduction of a methyl group at the 7-position of lithocholic acid appears to alleviate the cholestatic effect of lithocholic
acid in the hamster. 相似文献
17.
Kanazawa T Atsumi M Mineo H Fukushima M Nishimura N Noda T Chiji H 《Journal of oleo science》2008,57(6):335-343
Potato starch is known to have a higher concentration of phosphate than other starches. The presence of phosphate groups in amylopectin results in resistance to digestion by amylase. Therefore, there is a possibility that potato starch is slowly digested, inducing a physiological effect similar to that of resistant starch and indigestible oligosaccharides. The amount of phosphate group in starch differs with potato cultivar. In the present study, we investigated the effects of gelatinized potato starch containing a high level of phosphorus on lipid metabolism in rats. For this purpose, we determined lipid levels in the serum and liver in rats fed two kinds of gelatinized potato starches with different phosphorus contents. Four groups of male Sprague-Dawley rats were fed a 60% sucrose diet (control) or one of three diets containing cornstarch (CS), Benimaru (BM) potato starch or Hokkaikogane (HK) potato starch. Fat pad weight was slightly decreased in the HK diet group compared with that in the other groups. Free fatty acids in serum were significantly lowered by dietary HK starch compared with control, and serum triglyceride in rats fed the HK diet was also decreased. In the BM and HK diet groups, triglyceride levels in the liver were decreased compared with that in the control and CS groups. As for hepatic total cholesterol level, there were no significant differences among three starch diet groups. Fecal bile acid excretion was greater in the two potato starch groups than in the control group. On the other hand, there were no significant differences in cecal short-chain fatty acid content or pH. Thus, we conclude that dietary gelatinized potato starch reduces free fatty acid and triglyceride in serum and hepatic triglyceride, but does not affect cecal fermentation. 相似文献
18.
19.
The present study was undertaken to define the relationship between calcium metabolism and bile acid composition in animal
models of diet induced cholesterol and pigment gallstones. Groups of prairie dogs were fed either a control non-lithogenic
chow (N=12), a 1.2% cholesterol enriched chow (N=6, XOL) for two weeks, or a high carbohydrate diet deficient in iron (N=6,
CHO-FeD), or a high carbohydrate diet with normal iron levels (N=6, CHO) for eight weeks. Hepatic (HB) and gallbladder (GB)
bile samples were analyzed for total calcium, cholesterol, phospholipids, total bile acids (TBA), and individual bile acid
composition.
In each of the four groups, TBA concentrations were essentially similar and taurine conjugates accounted for approximately
90% of TBA in HB bile and about 98% in GB bile. In the control group, cholic acid (CA) was the predominant bile acid and comprised
76% of TBA and chenodeoxycholic (CDCA) accounted for about 13% of the total. Feeding a diet rich in cholesterol caused a significant
change in the relative concentrations of individual bile acids of hepatic bile—such that CA decreased significantly (p<0.001)
while CDCA increased by 300% (p<0.001). The changes in secondary bile acids were insignificant. An identical shift in individual
bile acid composition was noted in animals maintained on high carbohydrate diet, irrespective of iron content. Similar changes
were observed in the GB in the experimental groups.
Calcium concentrations of GB bile with or without gallstone formation showed a positive linear relationship with TBA (y=4.35+0.14X,
p<0.001) and taurochenodoxycholic acid (TCDCA) (y=15.04+0.46X, p<0.001), but an inverse relationship with taurocholic acid
(TCA) (Y=55.16−0.41X, p<0.008). However, such relationships were absent in hepatic bile. These data indicate that diet-induced
alterations in bile acid composition may modify calcium solubility or GB function, thereby contributing to the increased GB
calcium observed during cholesterol and pigment gallstone formation. 相似文献
20.
Kyoichi Osada Takehiro Kodama Koji Yamada Shingo Nakamura Michihiro Sugano 《Lipids》1998,33(8):757-764
The interactive effect of high dietary levels of oxidized cholesterol on exogenous cholerterol and linoleic acid metabolism
was examined in male 4-wk-old Sprague-Dawley rats given high-cholesterol diets. The rats were pair-fed purified diets free
of or containing either 0.5% cholesterol alone or both 0.5% cholesterol and 0.5% oxidized cholesterol mixture (containing
93% oxidized cholesterol) for 3 wk. Hepatic 3-hydroxy-3-methylglutaryl CoA reductase activity was reduced in rats given cholesterol
alone or both cholesterol and oxidized cholesterol. However, hepatic cholesterol 7α-hydroxylase activity was lowered only
when rats were given both cholesterol and oxidized cholesterol, although dietary cholesterol increased this activity. Reflecting
this effect, acidic steroid excretion was lowest among the groups of rats given cholesterol and oxidized cholesterol. On the
other hand, the activity of hepatic Δ6 desaturase, a key enzyme in the metabolism of linoleic acid to arachidonic acid, was
increased in rats given both cholesterol and oxidized cholesterol, although dietary cholesterol alone lowered its activity.
As a result, the Δ6 desaturation index, 20∶3n-6+20∶4n-6/18∶2n-6, in liver and serum phosphlipids tended to be higher in the
group fed both cholesterol and oxidized cholesterol than in the one fed cholesterol alone. Thus, dietary oxidized cholesterol
significantly modulated exogenous cholesterol metabolism and promoted linoleic acid desaturation even when it was given at
high levels together with a high cholesterol diet. 相似文献