首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Pooled adult normal rat plasma was used for the separation of lipoprotein fractions: VLDL, LDL and HDL, from which a total lipids extract was obtained. The presence of fragments with the MW of estrone and oleoyl-estrone in the lipoprotein fractions was analyzed by HPLC-MS. The results show that oleoyl-estrone is the major estrone component in lipoproteins; this molecular species was present in all three lipoprotein lipid extracts. The lipoprotein fractions were used for the analysis of protein and lipid classes: triacylglycerols, total and esterified cholesterol and phospholipids as well as acyl-estrone. About half of the total acyl-estrone was in the HDL fraction and only about 10% in the VLDL fraction. HDLs contained about one molecule in 50 particles, LDLs one molecule per particle and VLDLs 15 molecules per particle, i.e. given their size, the larger lipoproteins contained more oleoyl-estrone than the HDLs. The distribution of this hormone suggests that oleoyl-estrone is lost with other lipids as the lipoproteins shrink. The results presented show that oleoyl-estrone is a molecule found naturally in rat lipoproteins in low concentrations - the lowest in HDLs - that are consistent with its postulated role in the control of body weight.  相似文献   

2.
Preadipocytes (3T3 L1) were used between 7 and 14 days after differentiation; they were incubated with 44 nM 3H-esterone. The medium was supplemented with 1 M recombinant murine leptin, 10 nM recombinant human insulin, or 1 M corticosterone for up to 72 hr. In a second series of experiments, cells were incubated for 48 hr with different concentrations of leptin, insulin or corticosterone, and compared with controls (plain medium). Cells were harvested, washed in buffer and homogenized, and protein was measured. Lipid extracts of cell homogenates were used for HPLC; the label distribution in free and acyl-estrone peaks was measured. Overall uptake of estrone (i.e., the sum of free and acyl-estrone) by cells was not affected by leptin or corticosterone, but strongly reduced by insulin. Leptin and corticosterone increased the synthesis of acyl-esterone in a dose- and time-dependent way. Insulin decreased acyl-estrone synthesis at low concentrations and with little change over time. The results suggest that control of oleoyl-estrone deposition in adipocytes is modulated in at least two distinct steps: (a) estrone uptake, affected by insulin in the physiological range; and (b) synthesis of oleoyl-estrone from cell estrone. The latter may be affected by insulin, but leptin and corticosterone enhance the process.  相似文献   

3.
Oleoyl-estrone is a powerful, slimming adipose tissue-derived signal that has biological effects widely opposed to those of its estrone moiety. The present experiment was designed to determine whether oleoyl-estrone effects on body energy are mediated by the estrogen receptor, blocked with the antagonist tamoxifen. Male Wistar rats were given daily oral doses of 10 micromol/kg d of oleoyl-estrone in oil containing 0 or 0.40 mg/kg d of tamoxifen. The data were compared with controls receiving only oil or 50 nmol/kg d of free estrone. After 10 days, the rats were killed, and their body composition and plasma metabolites and hormones were analyzed. Rats receiving estrone increased their body energy and lipid content compared with controls. Both groups of oleoyl-estrone-treated rats lost body weight, energy, and lipid; the losses in the rats receiving tamoxifen alone were less marked than in those receiving oleoyl-estrone. No significant changes in plasma glucose or triacylglycerols were observed. The patterns of change of estrone sulphate, estradiol, and oleoyl-estrone were consistent with a noticeable hydrolysis of oleoyl-estrone. The lack of differences in the fat mass in oleoyl-estrone-treated rats irrespective of the presence of tamoxifen suggested that the estrogenic pathway was not responsible for the slimming effects observed. Thus, it can be concluded that oleoyl-estrone effects are not mediated through its conversion to estrone or estradiol acting through the estrogen receptor. Tamoxifen partly mimicked the slimming effects of oleoyl-estrone; this could be speculatively explained by tamoxifen acting through the oleoyl-estrone signalling pathway.  相似文献   

4.
Thirteen-week-old female Zucker lean (Fa/Fa) and obese (fa/fa) rats were injected through a cannula inserted in the left jugular vein with 1 mL/kg of 3H-labeled oleoyl-estrone in liposomes (Merlin-2) (i.e., 670 fmol, 84 kBq). The rats were killed 10 minutes later and dissected. The presence of intact or hydrolyzed oleoyl-estrone was later determined in all samples. The pattern of distribution of estrone was quite different from that of oleoyl-estrone both in rats that were lean and in those that were obese. Estrone was better retained by white adipose tissue than oleoyl-estrone. Liver, spleen, and lungs accumulated more oleoyl-estrone and split part of it, from 4.7% (lung, obese) to 27% (liver, lean). The overall high retention of estrone by the rat tissues results in its very low circulating levels. The fast splitting of liposome-carried oleoyl-estrone by most tissues (up to more than 67% by intestine and skin of lean rats) may help explain the rise in blood free estrone. The differences between lean and obese Zucker rats are mainly quantitative in the case of estrone, the main differences being found in blood and adipose tissues. However, when we compare the data for oleoyl-estrone, the differences cannot be dismissed simply as due to differences in body size or the extent of fat deposits. A large portion of the label remained in the blood of the rats that were obese but not in those that were lean, the tissues of which took up more label. Brown adipose tissue shows a fair affinity for oleoyl-estrone in the rats that were lean but practically does not retain label in the rats that were obese, suggesting that oleoyl-estrone may have a direct effect on brown adipose tissue. The decreased uptake of oleoyl-estrone in rats that were obese shows that the mechanism regulating the turnover or disposal of this signal is altered in this type of genetic obesity.  相似文献   

5.
An oral gavage of either 3, 1 or 0.1 mmoles of 14C-labelled glucose was given to rats under standard feeding conditions or food deprived for 24 hr. The fate of the glucose label was determined at 10, 15, 30 and 60 min after gavage; at 60 min 40% of the glucose was absorbed in fed rats (60% in food deprived). The portal vein blood flows were determined and the levels of glucose, lactate, alanine and pyruvate, and their radioactivity, as well as that of CO, were measured in both portal and arterial blood.The net computed glucose and 3-carbon carriers (lactate, alanine and pyruvate) actually released into the portal system by the intestine was lower than the amount of glucose taken up from the intestinal lumen in one hour. Oxidation to 14CO2 accounted for a 12–15% of the absorbed glucose. The size of the gavage deeply affected the proportion of glucose released into the portal blood (c. 50% with a 3 mmoles gavage and practically nil with a 0.1 mmoles gavage), but it affected much less the generation of lactate and other 3 C carriers. In fed rats, the net intestinal balance of non-radioactive glucose was negative, and that of lactate positive; when radioactive glucose was considered, the pattern was inverted. In starved rats, both glucose and lactate were released in large proportions by the intestine, but alanine efflux was lower.It can be concluded that the intestine consumes a considerable proportion of glucose in the fed state. Glucose handling by the intestine is compartmentalized in two functional circuits: glucose is taken up from the arterial blood and used for intestinal metabolism and lactate production, luminal glucose is absorbed mainly unaltered and transferred to the portal blood. Thus, the generation of lactate is mainly related to the availability of arterial glucose. In addition to the release of the ingested glucose as 3 C carriers or glucose, an extraportal pathway for glucose transfer into the bloodstream is postulated.  相似文献   

6.
Female adult rats were injected in the jugular vein with oleoyl-3H-estrone incorporated into liposomes. The label rapidly disappeared from the blood, being taken up by the tissues, mainly liver, spleen and lung, which filtered most of the label. However, many other tissues, such as the heart, brown adipose tissue, adrenals and visceral fat incorporated significant amounts of oleoyl-estrone. The analysis of the form in which the label remained 10 min after the injection showed that it was hydrolysed in a large proportion even in liver and lungs. However, in most tissues (brain, brown and white - periovaric - adipose tissues and ovaries), intact oleoyl-estrone accounted for less than one quarter of all tissue label, and less than 10% in the case of subcutaneous adipose tissue and uterus. This rapid destruction of oleoyl-estrone is in agreement with the active role of this compound in the control of body weight.  相似文献   

7.
Slices of pregnant guinea pig liver were incubated with (6,7-3H)estrone and with (6,7-3H)estradiol. Free, glucuro- and sulfo-conjugated fractions were isolated by specific extraction and hydrolysis. The radioactivity distribution in these 3 fractions demonstrated a predominance of conjugated compounds (95% of isolated estrogens) with slightly more glucuro-conjugated than sulfo-conjugated compounds. After isolating estrogens by TLC, we were able to determine estrone and estradiol in these 3 fractions from incubations with 3H-estrone or with 3H-estradiol by means of specific activity recrystallisation. Estriol was determined in glucuro-and sulfo-conjugated fractions after incubation with 3H-estrone as well as in sulfo-conjugated fraction after incubation with 3H-estradiol. Glucuro- or sulfo-conjugated estrone was the predominant estrogen after incubation with 3H-estrone just as after incubation with 3H-estradiol. This led us to conclude to an important 17beta-hydroxysteroid-dehydrogenase activity. The 16alpha-hydroxylastic-activity is weaker since estriol represented only 1,43 % of estrogens isolated after incubation with 3H-estrone and 0.82% after incubation with 3H-estradiol.  相似文献   

8.
Park YB  Jeon SM  Byun SJ  Kim HS  Choi MS 《Life sciences》2002,70(16):1849-1859
Areca extracts exhibiting a strong inhibitory activity against pancreatic cholesterol esterase (pCEase) in vitro were previously found to lower the absorption of dietary cholesteryl ester. Therefore, to determine whether a combined Areca extract also affects the absorption of intestinal free cholesterol, male rats were fed a diet containing free cholesterol (1%, w/w) either with or without an Areca nut extract supplement (0.5%, w/w). The Areca extract supplement significantly lowered the plasma cholesterol concentration by 25% without any change in the plasma triglyceride concentration, when compared to the control group. The supplement also significantly lowered the small intestinal pCEase activity by 39.1% compared to that of the control group. As regards the hepatic and intestinal ACAT activities, only the intestinal enzyme activity was significantly lowered by the supplement, when compared to the control group. The absorbed cholesterol that appeared in the blood after an oral dose of [1,2(n)-3H] free cholesterol was significantly lower in the rats supplemented with the Areca nut extract, compared with the control group. These results suggest that the inhibition of intestinal ACAT and possibly pCEase may facilitate the metabolic efficiency of the Areca nut extract as regards the absorption of intestinal free cholesterol. The structure and chemical properties of the active compound in the water-soluble Areca extract remain to be elucidated.  相似文献   

9.
The intestinal content, the mucosa and the rest of the intestinal wall of germfree (GF) and conventional ( CVL ) rats were tested for in vitro hydrolysis of [3H]estrone sulfate. In homogenates from GF rat intestine some estrone sulfate hydrolysis was detected in those from the proximal small intestine (PSI) (4.2 +/- 0.1% hydrolyzed after 4 h), but not in those from the distal small intestine (DSI) and the caecum. Estrone sulfate was also hydrolyzed by the homogenates of the mucosa and the rest of the intestinal wall from each of the segments tested (PSI: 12.8 +/- 0.4% (mucosa) and 21.5 +/- 2.1 (wall); DSI: 8.2 +/- 0.9% (mucosa) and 17.3 +/- 1.7% (wall); caecum: 8.8 +/- 1.6% (mucosa) and 17.3 +/- 0.5% (wall) ). In the homogenates of CVL rat intestine, the estrone sulfatase activity in the rest of the intestinal wall did not differ considerably from the values for GF rats, when expressed per mg protein of the homogenate. The mucosa of the CVL rats, however, showed higher rates of hydrolysis than the mucosa of the GF rats. The microbial estrone sulfatase activity in the intestinal content of CVL rats, tested by anaerobic incubation, was high in the caecum (91.7 +/- 6.6% after 4 h), but very low in the PSI (2.2 +/- 0.7%) and DSI (1.3 +/- 0.5%). Serial dilutions of the caecal content also showed higher viable numbers of estrone sulfate hydrolyzing bacteria. These results add further weight to the suggestion that estrone sulfate may be absorbed from the small intestine, but has to be hydrolyzed in the caecum by the gut microflora prior to absorption.  相似文献   

10.
Summary (1) Attempts to determine the redox-state of the absorbed iron, which appeared in the portal blood when the free iron-binding capacity was previously saturated, indicate that about 30–90% of this iron was in the ferrous state. This effect was particularly prominent after luminal administration of ferrous iron, but was also seen when iron was given in the ferric state. (2) Total iron absorption is significantly higher in ceruloplasmin-substituted copper-deficient animals as compared to copper-deficient controls. (3) The appearance rate of absorbed iron in the portal blood of copper-deficient animals increased several times immediately after the intravenous infusion of ceruloplasmin. (5) The distribution of absorbed iron was changed due to the ceruloplasmin substitution: it was increased in the reticulocytes (+66%), plasma (+400%) and the body (+ 112%), whereas in the liver it was decreased by about 78%. (5) In iron-deficient rats intravenously injected ceruloplasmin did not increase iron absorption. (6) The conclusion was drawn that, as for the entrance into the mucosa from the luminal side, also for the release at the contraluminal side into the portal blood, the ferrous state of iron is favoured and that ceruloplasmin accelerates the release into the portal blood by catalyzing the oxidation of ferrous iron due to its high Fe(II):oxygen oxidoreductase (EC 1.16.3.1) activity.  相似文献   

11.
To test whether oleoyl-estrone plus a hyperlipidic diet affects body weight in Zucker fa/fa rats, 13-week-old male Zucker obese (fa/fa) rats initially weighing 440-470 g were used. They were fed for 15 days with a powdered hyperlipidic diet (16.97 MJ/kg metabolizable energy) in which 46.6% was lipid-derived and 16.1% was protein-derived energy and containing 1.23 +/- 0.39 μmol/kg of fatty-acyl esters of estrone. This diet was supplemented with added oleoyl-estrone to produce a diet with 33.3 μmol/kg of fatty-acyl estrone. Oral administration of oleoyl-estrone in a hyperlipidic diet (at a mean dose of 0.5 μmol. kg(-1).d(-1)) resulted in significant losses of fat, energy and, ultimately, weight. Treatment induced the maintenance of energy expenditure combined with lower food intake, creating an energy gap that was filled with internal fat stores while preserving body protein, in contrast with the marked growth of controls fed the hyperlipidic diet. Treatment of genetically obese rats with a hyperlipidic diet containing additional oleoyl-estrone resulted in the loss of fat reserves with scant modification of other metabolic parameters, except for lower plasma glucose and insulin levels. The results agree with the postulated role of oleoyl-estrone as a ponderostat signal.  相似文献   

12.
Oral doses of estrone from 10 nmol/(kg day) to 10 micromol/(kg day) were given to adult Wistar male rats for 10 days. Body composition, energy balance, total body estrone balance and plasma metabolites and hormones were measured at the end of the treatment. Body weight (as well as food intake, body energy, fat and water accrual) increased at doses in the 10--100 nmol/(kg day) range, but decreased at higher doses. Energy expenditure decreased with increasing doses of estrone. Plasma metabolite changes suggested the maintenance of energy homeostasis, and lipid parameters indicated that lipid mobilization increased with the increasing doses of estrone. Plasma estrone, acyl-estrone and estradiol levels decreased at low doses and increased at high doses of estrone. We conclude that: (a) repeated estrone gavages, even at very high doses, do not result in the accrual of estrone in the body; (b) low doses of estrone promote growth and high doses decrease body mass and fat accretion; (c) administration of estrone at low doses decreases its circulating levels and the levels of estradiol and acyl-estrone, a situation reverted at higher doses and (d) estrone administration induces a dose-dependent shift towards lower energy expenditure.  相似文献   

13.
1. The appearance of exogenous cholesterol in free cholesterol and ester cholesterol of plasma chylomicra, very-low-density (VLD), low-density (LD) and high-density (HD) lipoproteins was studied in unanaesthetized rabbits after ingestion of a meal containing 5% fat and 0.08% [3H]cholesterol. 2. The specific radioactivity of ester cholesterol of VLD lipoproteins reached the highest value of any lipoprotein fraction and for each lipoprotein it increased at a faster rate and reached a higher maximum than that of free cholesterol; the maximum in VLD lipoproteins occurred later than in chylomicra. 3. The pattern of appearance of exogenous cholesterol in chylomicra and VLD lipoproteins of plasma was similar to the pattern previously observed in lymph. The specific radioactivity of ester cholesterol in plasma VLD lipoproteins was higher than that in chylomicra in spite of a larger pool size and dilution of cholesteryl esters from VLD lipoproteins produced by the liver. These results support the concept that during absorption the major portion of exogenous cholesterol is transported in VLD lipoproteins as ester cholesterol. 4. The specific radioactivity of ester cholesterol of chylomicra and VLD lipoproteins increased at a faster rate than that of LD and HD lipoproteins. However, the rate of increase and the absolute values of the specific radioactivity in LD and HD lipoproteins were identical. Since cholesteryl esters are thought not to exchange between lipoproteins, this observation supports the hypothesis that a result of VLD lipoprotein and chylomicron metabolism is the formation of LD and HD lipoproteins. 5. Results in vivo showed that the free cholesterol of individual plasma lipoproteins does not equilibrate within a period of 24h.  相似文献   

14.
15.
This study investigated the pharmacokinetic properties of crocin following oral administration in rats. After a single oral dose, crocin was undetected while crocetin, a metabolite of crocin, was found in plasma at low concentrations. Simultaneously, crocin was largely present in feces and intestinal contents within 24h. After repeated oral doses for 6 days, crocin remained undetected in plasma and plasma crocetin concentrations were comparable to the corresponding data obtained after the single oral dose. Furthermore, the absorption characteristics of crocin were evaluated in situ using an intestinal recirculation perfusion method. During recirculation, crocin was undetected and low concentrations of crocetin were detected in plasma. The concentrations of crocin in the perfusate were reduced through different intestinal segments, and the quantities of drug lost were greater throughout the colon. These results indicate that (1) orally administered crocin is not absorbed either after a single dose or repeated doses, (2) crocin is excreted largely through the intestinal tract following oral administration, (3) plasma crocetin concentrations do not tend to accumulate with repeated oral doses of crocin, and (4) the intestinal tract serves as an important site for crocin hydrolysis.  相似文献   

16.
In subjects fed a cholesterol-free diet there are three possible sources of intestinal lymph cholesterol: a) mucosal synthesis; b) absorption of endogenous (biliary) cholesterol; and c) transudation of plasma lipoproteins into the lacteals of the intestinal wall. To test these possibilities, the extent of transudation was measured by means of [3H]beta-sitosterol administered intravenously as a marker. Absorption of biliary cholesterol was reduced by oral administration of beta-sitosterol (9 g/day), and mucosal synthesis of cholesterol was evaluated by comparisons of plasma/lymph [14C]cholesterol specific activity ratios after intravenous administration of a single dose of labeled cholesterol. Studies were carried out on six patients with filarial chyluria. In five patients fed a cholesterol-free diet the results indicated that lymph cholesterol was largely derived by transudation of plasma lipoproteins into the lacteals from the intestinal blood supply, without contribution from de novo mucosal synthesis or from absorption of endogenous cholesterol. The intestinal lymph of one patient fed cholesterol (2 g/day) contained cholesterol originating mostly from plasma transudation and from dietary absorption, with little contribution from absorbed endogenous cholesterol. In all experiments the larger part of the cholesterol transported away from the intestine in the lymph was carried in chylomicrons, even though it had its origin in plasma lipoproteins.  相似文献   

17.
C Longcope  J H Pratt 《Steroids》1977,29(4):483-492
On the basis of the ratios of the estrogen conjugates in their urine (estriol/estrone + estradiol: E3/[E1+E2]), 19 women were divided into two groups: 9 women had ratios less than 0.6 and 10 women had ratios greater than 1.3. All women had measurements made of endogenous estrogens in their plasma by radioimmunoassay. They were then given constant infusions of 3H-estrone, 3H-estradiol and 14C-estriol during days 5-7 and days 20-22 of their cycles, and metabolic clearance rates (MCR) and blood production rates (PB) of estrone, estradiol and estriol were determined. Despite the wide disparity in their ratios of urinary estrogens, no differences could be found between the groups for the MCR's and PB's for all estrogens at either time of the cycle. The mean ratios of PB's (PB3/[PB2+PB1]) of estrone, estradiol and estriol ranged from 0.07 to 0.10 for each group during the cycle. The amounts of estriol entering the blood are small compared to the amounts of estrone and estradiol and do not correlate with the ratios of their urinary conjugates.  相似文献   

18.
The intestinal absorption of β-1,4-mannobiose by rats was investigated. Mannobiose was detected in the portal vein plasma by matrix-assisted laser desorption ionization/time of flight mass spectrometry after its administration to rats. The presence of mannobiose in the rat plasma was confirmed by an experiment using β-mannosidase. These results indicate that mannobiose was directly absorbed through the intestines even without being hydrolyzed.  相似文献   

19.
Objective: To establish whether single daily oral doses of oleoyl‐estrone result in dose‐dependent slimming effects on normal weight rats, and to determine the changes in energy parameters induced by this treatment. Research Methods and Procedures: The effects of a daily oral gavage of oleoyl‐estrone (0, 0.2, 0.5, 1, 2, 5, 10, and 20 μmol/kg per day) in 0.2 ml of sunflower oil given over a 10‐day period were studied in groups, each of which contained six adult female Wistar rats initially weighing 190 to 230 g. A group of intact control rats receiving no gavage was included for comparison. Body weight and food intake were measured daily. Rats were killed on day 10 of treatment, and body composition (protein nitrogen, lipids, and water), liver lipids, and plasma parameters (glucose, triacylglycerols, total cholesterol, free fatty acids, 3‐hydroxybutyrate, urea, aspartate, alanine transaminases, insulin, leptin, and free and acyl‐estrone) were measured. Results: The administration of oleoyl‐estrone resulted in a dose‐dependent loss of body fat, because of a partly maintained energy expenditure combined with decreased food intake. The differences in the energy budget were met by internal fat pools. The changes recorded did not affect the levels of the main plasma energy homeostasis indicators: unaltered glucose, triacylglycerols, free fatty acids, 3hydroxybutyrate, and urea. Protein was accrued even under conditions of severe lipid store drainage. There were no changes in transaminases. No lipid accumulation was recorded in the liver. Plasma insulin and leptin levels decreased with increased oleoyl‐estrone doses, whereas the levels of free and esterified estrone increased with treatment, although not in proportion to the dose received. Discussion: Oral treatment with oleoyl‐estrone resulted in the specific dose‐related loss of fat reserves with little change to other metabolic parameters. These results agree with the postulated role of oleoyl‐estrone as a ponderostat signal.  相似文献   

20.
目的:研究缬沙坦对动脉粥样硬化兔血清IL-8和TNF-α水平的影响。方法:将30只实验兔随机分为3组,每组10只,即正常对照组:喂以普通饲料;高脂饮食组:喂以高脂饮食(含15%蛋黄粉,0.5%胆固醇和5%猪油的饲料)6周,后给予10 ml/d生理盐水4周;药物干预组:喂以高脂饮食6周,后给予缬沙坦(10 mg/kg/d)治疗4周。饲养6周和10周时分别经兔耳缘静脉取血,通过酶联免疫法检测各组兔血清中IL-8和TNF-α的水平。结果:饲养第6周时,高脂饮食组和药物干预组兔血清TNF-α和IL-8水平均较正常对照组明显升高,差异均具有统计学意义(P〈0.05),而高脂饮食组与药物干预组比较差异无统计学意义(P〉0.05)。饲养第10周时,即缬沙坦干预4周后,药物干预组与建模6周时比较,血清TNF-α及IL-8水平均明显下降,差异具有统计学意义(P〈0.05),且与高脂饮食组比较,血清TNF-α及IL-8水平亦明显下降,差异具有统计学意义(P〈0.05)。结论:动脉粥样硬化时,血清IL-8和TNF-α升高,缬沙坦能明显降低动脉粥样硬化中IL-8和TNF-α水平,从而发挥抗动脉粥样硬化作用。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号