Effects of a chitosan intake on the fecal excretion of dioxins and fat in rats

We evaluated the effects of the intake of various dietary fibers on the fecal excretion of dioxins in rats. The rats were fed five types of dietary fiber diets, including a chitosan diet and control diet, for 20 d and then dioxins (120 ng/rat) were orally administered on day 15. The excretion of fecal dioxins was significantly higher in the chitosan group than in the control group, and dioxin excretion was positively correlated with fecal fat excretion. A comparison of the different types of chitosan showed that the efficacy of chitosan for fecal fat excretion was partly related to its viscosity. The chitosan intake promoted fecal dioxin excretion when the rats were exposed to highly toxic dioxins, and this excretion of fecal dioxins was related to the fecal fat excretion, suggesting that chitosan might be useful for reducing the adverse effects caused by lipophilic xenobiotics.     

Effects of chitosan intake on fecal excretion of bisphenol A and di(2-ethyl)phthalate in rats

We evaluated the effects of chitosan intake on fecal excretion of bisphenol A (BPA) and di(2-ethyl)phthalate (DEHP) in rats. The rats were fed a chitosan diet (CHI group) or a control diet (control group) for 10 d and orally administrated BPA or DEHP (100, 500 mg/kg body weight, respectively) on day 4. Feces were collected and the rates of fecal excretion of BPA and DEHP were calculated. Fecal excretion rates of BPA and DEHP were significantly higher in the CHI group than in the control group. A significant negative correlation was observed between the fecal excretion rates of BPA and DEHP and apparent fat digestibility. Furthermore, the CHI group showed not only increased but also accelerated BPA excretion into the feces. In conclusion, we found that that chitosan intake significantly increased the fecal excretion of BPA, DEHP, and fat, suggesting that it might be useful for reducing adverse effects caused by lipophilic xenobiotics.     

Effects of Arachis hypogaea nutshell extract on lipid metabolic enzymes and obesity parameters

The aim of the present study was to assess the effects of peanut (Arachis hypogaea L.) shell extracts (PSE) on lipases and to evaluate its potential development for the treatment of obesity. The peanut shells were extracted in 95% ethanol, and the extracts were screened for inhibitory effects on pancreatic lipase (PL) and lipoprotein lipase (LPL) activities as well as on lipolysis of 3T3-L1 adipocytes. We also examined in vivo whether PSE could prevent the body weight gain induced by feeding a high-fat diet to male Wistar rats for 12 weeks. PSE inhibits a number of lipases, including PL, LPL and, possibly, hormone sensitive lipase (HSL). PSE-treated Wistar rats showed increased fecal lipid excretion respect to the control group. Body weight and body weight gain, and liver size, were significantly lower in rats fed the high-fat diet with 1% of PSE (w:w diet) than in those fed the high-fat diet alone. The rats treated with PSE showed reduced triacylglycerol content in the liver, as well as the serum glucose and insulin. The inhibitory activity of PSE on the lipid metabolic enzymes and the increase in fecal fat excretion suggests that PSE might be useful as a treatment to reduce the dietary fat absorption. The observed reduction in intracellular lipolytic activity of cultured 3T3-L1 adipocytes may reduce the levels of circulating free fatty acids. The observed effects are likely induced by more than one bioactive component of PSE. The PSE actions may, at least in part, be attributed to the inhibition of fat absorption in the digestive tract and the reduction of the adipocyte lipolysis.     

Effect of wheat bran on excretion of radioactively labeled estradiol-17 beta and estrone-glucuronide injected intravenously in male rats.

Urinary and fecal estrogen excretion were studied in male rats fed a non-fiber wheat starch diet (dietary fiber less than 1%; NF group; n = 4), a low-fiber wheat flour diet (dietary fiber 2%; LF group; n = 4) or a high-fiber wheat bran diet (dietary fiber 11.6%; HF group; n = 3). Short-term effects of the experimental diet on estrogen excretion were studied after i.v. injection of 5 microCi (0.185 MBq) of [14C]estradiol-17 beta (E2) into the tail vein of the rats fed the diets for 2 days. After 3 weeks on the experimental diets, the long-term effects were studied after injection of 5 microCi of [14C]E2 and 10 microCi of [3H]estrone-3-glucuronide (E1-gluc). The diet was found to affect estrogen excretion. The short-term effect indicated that rats fed the HF diet excreted a relatively large amount of labeled compounds in the feces during the first day after injection, while rats fed the NF or the LF diets excreted about half that amount over the same period. On the other hand, urinary excretion of labeled compounds was significantly higher in the NF and LF rats. The long-term effect resulted in steeper slopes (P less than 0.05) of the fecal excretion profiles of rats fed the HF diet as compared with rats fed the NF and LF diets, indicating an accelerated fecal excretion of labeled compounds in the HF rats. The kinetic profiles of 14C and 3H radioactivity in blood plasma indicated a fast decrease (t1/2 of less than 2 min) for both [14C]E2 and [3H]E1-gluc. It was concluded that, owing to the short-term effect of wheat bran intake, during the first 24 h after i.v. administration relatively large amounts of radioactively labeled compounds are excreted in feces of rats fed the HF diet. In contrast, excretion is lower in urine of these rats. When the microflora is adapted to the experimental diet the wheat bran diet still results in an accelerated fecal excretion of labeled compounds, which might be attributed to an interruption of the enterohepatic circulation of estrogens. This might result in lowered plasma and/or tissue estrogen levels and hence a decreased exposure of estrogen-sensitive tissue to estrogens, which might decrease risk on mammary (breast) cancer development.     

Effect of coix on plasma, liver, and fecal lipid components in the rat fed on lard- or soybean oil-cholesterol diet

To determine the influence of dietary coix on lipid metabolism, the effect of coix on plasma, liver, and fecal lipid components was studied using Sprague-Dawley male rats. All rats were divided into four groups, and the rats of each group were fed the coix-lard diet, coix-soybean oil diet, or the respective control diets (containing 1% cholesterol each) for 27 days. Plasma and liver cholesterol levels in the coix-lard diet group significantly decreased as compared with those in the control group, whereas there was no effect on the fecal excretion of cholesterol. The decreases in the concentrated liver triglyceride and the increases in the fecal excretion of triglyceride were found in coix-soybean oil diet group. Moreover, liver and fecal phospholipid levels in both coix diet groups significantly increased. But there were no significant changes in plasma and fecal bile acids in either coix diet group. These results suggest the possibilities that coix may have an inhibitory action on cholesterol synthesis in liver, a facilitating effect on biliary excretion of triglyceride, and an acceleratory action on phospholipid synthesis in liver.     

High Dietary Calcium Reduces Body Fat Content,Digestibility of Fat,and Serum Vitamin D in Rats

Objective: This study investigated which aspect of energy balance was responsible for the decrease in body fat content of rats fed a high‐calcium, high—dairy protein diet. Research Methods and Procedures: Male Wistar rats were fed a control diet (25% kcal fat, 14% kcal protein from casein, 0.4% by weight calcium) or high‐calcium diet (25% kcal fat, 7% kcal protein from nonfat dry milk, 7% kcal protein from casein, 2.4% calcium) for 85 days. Body weights, digestible energy intakes, energy expenditures, rectal temperatures, body composition, and serum glucose, insulin, free fatty acids, triglycerides, and 1, 25‐dihydroxyvitamin D were measured. Results: Rats fed high‐calcium diet gained significantly less weight than controls and had 29% less carcass fat. Gross energy intake was not significantly different between groups, but digestible energy was 90% of gross energy in the high‐calcium diet compared with 94% in the control diet because of increased fecal excretion of dietary lipid. The difference in digestible energy intake accounted for differences in carcass energy. Body temperatures and energy expenditures of the rats were not different. The high‐calcium diet reduced serum triglycerides by 23% and serum 1, 25‐dihydroxyvitamin D by 86%. Discussion: These results confirm that a high‐calcium diet decreases body weight and fat content due to a lower digestible energy intake caused by increased fecal lipid and a nonsignificant reduction in gross energy intake.     

Copper absorption,endogenous excretion,and distribution in Sprague-Dawley and lean (Fa/Fa) Zucker rats

We previously observed a rapid reduction in plasma ceruloplasmin activity in lean Zucker (Fa/Fa) rats fed a marginal copper (Cu)-deficient diet compared to similarly fed obese Zucker (fa/fa) and lean Sprague-Dawley rats. In an effort to understand the mechanisms underlying this response, we utilized the isotope dilution method to investigate the absorption and excretion of Cu in lean Zucker rats fed control and marginal Cu diets. Sprague-Dawley (SD) and homozygous lean Zucker rats were fed either a Cu-adequate (Cont; 7.5 μg Cu/g diet) or a low Cu (Low; 1.1 μg Cu/g diet) casein-based diet for 23 d. Two weeks following initiation of the dietary treatment, each rat was injected intramuscularly (im) with 11.2 μCi of⁶⁷Cu. Urine and feces were collected daily. On the 9th d following isotope injection, rats were killed and tissues collected. Significant dietary effects were observed in the relative absorption and endogenous fecal excretion of⁶⁷Cu. The tissue distributions of nonisotopic Cu and⁶⁷Cu activity were also different between dietary treatments. Tissues from rats fed the low-Cu diet typically had high concentrations of⁶⁷Cu and low concentrations of nonisotopic Cu compared to controls. An increase in relative⁶⁷Cu absorption was evident for rats fed the low-Cu diet (57.2 and 39.3%, for SD Low, Zucker Low, respectively, and 17.9, and 28.5% SD Cont and Zucker Cont, respectively). Rats fed the low-Cu diet also had reductions in endogenous fecal excretion of⁶⁷Cu compared to their respective controls. Although strain effects were not evident for either percent Cu absorption or endogenous fecal Cu excretion, the relative adaptive changes appeared more marked for the Sprague-Dawley rats compared to the lean Zucker rats.     

Effect of dietary protein, alfalfa, and zeolite on excretory patterns of 5',5',7',7'-[3H]zearalenone in rats

A series of experiments was conducted to determine how dietary protein, alfalfa, or zeolite influence the excretory patterns of zearalenone (Z), a uterotropic mycotoxin synthesized by Fusarium fungi. Rats were fed diets containing 16.3% casein, 40% casein, 11.2% casein + 25% alfalfa, or 25% casein + 25% alfalfa. Also fed were diets containing 0, 1, 2, or 5% anion exchange zeolite. Tracer doses of [3H]Z were administered either as a constituent of the diet or as a topical application on the skin at the base of the skull. When Z was administered orally, no differences were seen in the fraction of the dose excreted in urine or feces as a result of varying dietary levels of alfalfa and protein. Topical doses resulted in rats fed 25% casein + 25% alfalfa or 40% casein excreting more Z in urine than those fed 25% alfalfa or 16.3% casein. Fecal excretion of Z was greatest for rats fed 25% casein + 25% alfalfa whereas rats fed 40% casein excreted more fecal Z than those fed 16.3% casein. Feeding Z to rats receiving dietary zeolite resulted in a positive correlation between dietary zeolite and fecal excretion of Z but a negative correlation with urinary excretion of Z. Topical administration of Z produced a positive correlation between dietary zeolite and fecal Z excretion but no effect on urinary excretion. It may be concluded that protein and alfalfa treatments alleviate Z toxicosis through increased metabolism whereas zeolite binds Z in the digestive tract to prevent absorption.     

Antiobesity effect of recombinant human caseinomacropeptide in Sprague-Dawley rat

Caseinomacropeptide (CMP) is a glycopeptide of 64 amino acid residues derived from theC-terminal of mammalian milkk-casein. Recently, human CMP (hCMP) was produced from the recombinant yeastSaccharomyces cerevisiae. In this study, the antiobesity activity of the recombinant hCMP (rhCMP) was investigatedin vivo using Sprague-Dawley rats. The rhCMP did not affect the rats fed with a normal fat diet (fat content, 5.0%), but decreased the body weight gain of the rats fed with a high fat diet (fat content, 20%) by up to 19%. Autopsies revealed that the weights of the liver, kidney and adipose tissues decreased when the rats were given the rhCMP, which also reduced the lipid concentrations in the plasma and liver, but enhanced the fecal excretion of lipids. These results suggest that rhCMP prevent the accumulation of lipid by stimulating its fecal excretion, so could be used as a food supplement to alleviate the obesity problem caused by a high fat diet.     

Effect of dietary chitosans with different viscosity on plasma lipids and lipid peroxidation in rats fed on a diet enriched with cholesterol

To investigate the effect of dietary chitosan on lipid metabolism, male SD (Sprague-Dawley) rats were fed a cholesterol-enriched diet containing 5% cellulose (CE), 5% chitosan (CCS; high viscosity), or 5% chitosan (FCS; low viscosity) for 4 weeks. The two types of chitosan with a comparable degree of deacetylation had a different molecular weight and intrinsic viscosity. Significantly (p < 0.05) lower plasma total cholesterol, LDL-cholesterol and VLDL-cholesterol concentrations were observed in the rats fed on the chitosan diets. In addition, chitosan significantly increased the fecal cholesterol and triglyceride contents. Although no significant difference in body weight was found among the dietary groups, the rats fed on the chitosan diets had lower relative liver weight when compared with those fed on the cellulose diet. Both of the chitosan groups had significantly lower liver total lipid and total cholesterol contents compared to the cellulose group, although the FCS group was less effective. The plasma and liver thiobarbituric acid reactive substances (TBAR) values were similar in the CE and FCS groups, while the CCS group had increased liver TBAR values. Although a significant increase in liver glucose-6-phosphate dehydrogenase activity was observed in the CCS group, no significant change was found in the FCS group. The observed influence of chitosans with different viscosity on the plasma lipid level, liver lipids and lipid peroxidation suggests that, while the hypocholesterolemic action of chitosans with different viscosity was similar, changes in the liver lipids and liver peroxidation status depended on their molecular weight when the deacetylation degree was comparable.     

Dietary soybean protein moderates the deleterious disturbance of lipid metabolism caused by exogenous oxidized cholesterol in rats.

Effects of dietary protein on oxidized cholesterol-induced disturbance of lipid metabolism were examined in 4 week old male Sprague-Dawley rats, using casein and soybean protein as dietary protein source. The rats were given one of the two proteins in 0. 078% cholesterol (control), 0.25% cholesterol or 0.25% oxidized cholesterol mixture (containing 0.078% cholesterol) diets. Dietary oxidized cholesterol, compared to cholesterol, tended to inhibit hepatic sterol biosynthesis in casein-fed rats, whereas this inhibitory action was slightly moderated by intake of soybean protein. As a result, the hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity was rather higher in the rats fed oxidized cholesterol than in those fed cholesterol in the soybean protein-fed group. The hepatic cholesterol 7alpha-hydroxylase activity tended to be higher in the rats fed oxidized cholesterol than in those fed control diet in the soybean protein-fed group, despite the fact that oxidized cholesterol lowered the hydroxylase activity in the casein-fed group. On the other hand, dietary oxidized cholesterol tended to slightly enhance the hepatic Delta6 desaturase activity in the casein-fed group; however, this observation was not shown in the soybean protein-fed group. Moreover, dietary soybean protein facilitated fecal oxidized cholesterol excretion and simultaneously inhibited the accumulation of oxidized cholesterol in serum and liver. In conclusion, dietary soybean protein alleviated the deleterious actions of exogenous oxidized cholesterol on hepatic cholesterol and linoleic acid metabolism, although these efficacies were not necessarily significant. A great part of these moderations may be exerted by the specific hypocholesterolemic function of soybean protein, such as the stimulation of fecal oxidized cholesterol excretion, the change of hormonal release and modulation of lipoprotein catabolism.     

Use of 3H-labeled triether, a nonabsorbable oil-phase marker, to estimate fat absorption in rats with cholestyramine-induced steatorrhea

A tritium-labeled glycerol triether was tested as a nonabsorbable oil-phase marker in studies of fat absorption in normal rats and in rats with steatorrhea induced by various doses of cholestyramine. Animals were fed a test meal containing (3)H-labeled triether and (14)C-labeled trilinolein. Fat absorption was estimated in the following three ways: (a) by isotope ratios (the change in (3)H/(14)C in the test meal and in feces); (b) by isotope recovery (the total fecal excretion of (14)C radioactivity); and (c) by chemical recovery (the total fecal fat excretion). Absorption calculated from isotope ratios agreed well with that calculated from isotope recovery over a range of fat absorption of 50-100%, thus validating the use of this lipid marker under these conditions of fat malabsorption. Absorption calculated from chemical recovery was consistently poorer than that calculated from isotope ratios or isotope recovery, thus suggesting that cholestyramine increased the excretion of nondietary (endogenous) fat. Triether may be of value for studying the absorption of compounds present predominantly in the oil phase during digestion and may have significant advantages over other proposed lipid markers.     

Comparative Evaluation of Fecal Fat Excretion Induced by Orlistat and Chitosan

Objective: To compare the effects of chitosan and orlistat on fecal fat excretion. Research Methods and Procedure: A randomized, open‐label, two‐period sequential design study was used. A total of 12 healthy adult volunteers within 20% of their ideal body weight entered a 7‐day run‐in diet period before being randomized to orlistat (120 mg) or chitosan (890 mg) three times daily for 7 days. Subjects then crossed over treatment regimens for an additional 7‐day period. Subjects followed a standardized diet (2500 kcal/d, 30% as fat) for the entire 21‐day study. Feces were collected on days 4 to 7 of the run‐in period (baseline) and during the two treatment periods. Mean daily fecal fat excretion was measured at baseline and during each treatment regimen. Results: Mean baseline fecal fat excretion for all subjects was 1.36 ± 0.45 g/d. During orlistat treatment, mean fecal fat excretion significantly increased from baseline (+16.13 ± 7.27 g/d; p < 0.001). No significant effect was observed with chitosan (+0.27 ± 1.02 g/d; p = 0.379). Fecal fat excretion was significantly greater with orlistat than with chitosan (p < 0.001; 95% confidence intervals: 11.73; 20.00 g/d). Discussion: This study provides additional evidence of the inhibitory effect of orlistat on dietary fat absorption. Chitosan, however, has no effect on fecal fat excretion.     

一株植物乳杆菌Lp3对高脂模型大鼠的益生作用

【目的】本研究通过构建大鼠高脂结构模型来探究一株植物乳杆菌Lp3的益生作用。【方法】植物乳杆菌Lp3筛选自青藏高原地区传统发酵的牦牛酸奶,初步认定Lp3是一株具有良好耐受力的降胆固醇菌株,且体外益生特性突出,本研究通过建立高脂SD大鼠模型,在饲喂试验动物高脂饲料的同时灌胃植物乳杆菌Lp3,来确定该菌株对试验动物血脂的影响效果,并同时研究其对大鼠肠道菌群、粪便水分、粪便中胆固醇和胆汁酸含量的影响,以及对肝脏组织中的胆固醇(TC)和甘油三酯(TG)的影响。【结果】结果表明,植物乳杆菌Lp3对大鼠没有任何明显的毒副作用,对高脂模型大鼠具有良好的降血脂效果。饲喂高脂饲料并灌喂乳酸菌Lp3组大鼠(HL)的血清总胆固醇、甘油三酯和低密度脂蛋白胆固醇含量较饲喂高脂饲料组(HC)显著减少(P0.05),但是高密度脂蛋白胆固醇的含量变化并不明显。HC组大鼠与HL组及饲喂普通日粮组(对照组)大鼠相比较,HC组大鼠粪便中大肠杆菌数量明显增加,双歧杆菌、乳杆菌数量明显减少。但是灌胃乳酸菌的HL组大鼠的粪便中乳杆菌数略高于对照组,大肠杆菌和双歧杆菌数量和对照组大鼠的基本一致。表明植物乳杆菌Lp3具有维持肠道菌群平衡的作用。此外灌胃乳酸菌后HL组大鼠粪便含水量比HC组要高6.44%。HC组大鼠肝脏组织中胆固醇和甘油三酯要显著高于HL组(P0.05),说明Lp3可以减少脂类物质在肝脏组织中的沉积。从肝脏组织切片来看,也可以得出上述结论。【结论】结果表明本研究所筛选的植物乳杆菌Lp3对高脂大鼠具有值得深入研究的益生作用。     

Evaluation of nutrient digestibility and fecal characteristics of exotic felids fed horse‐ or beef‐based diets: use of the domestic cat as a model for exotic felids

The objective of this study was to determine the effects of feeding commercially available beef‐ and horse‐based diets on nutrient digestibility and fecal characteristics of large captive exotic felids and domestic cats. Four species of large exotic felids including cheetahs, Malayan tigers, jaguars, and Amur tigers, and domestic cats were utilized in a crossover design. Raw meat diets included a beef‐based diet (57% protein; 28% fat) and a horse‐based diet (51% protein; 30% fat). All cats were acclimated to the diet for 16 days followed by a 4 day collection period, where total feces, including one fresh sample, were collected. All feces were scored on collection. Intake did not differ due to diet, but fecal output was greater when cats consumed the horse‐based diet. Total tract apparent dry matter (DM) digestibility was higher (P<0.05) and organic matter (OM) and crude protein (CP) digestibilities were lower (P<0.05) when cats were fed the beef‐based diet compared with the horse‐based diet. CP digestibility was similar in domestic cats and cheetahs, and greater (P<0.05) than Amur tigers. Fecal scores were lower and fecal DM was greater (P<0.05) when cats consumed the horse‐based diet compared with the beef‐based diet. Domestic cats had lower (P<0.05) fecal ammonia concentrations compared with all other species. Fecal ammonia concentrations were lowest (P<0.05) when cats were fed the horse‐based diet. Fecal total short‐chain fatty acid (SCFA), branched‐chain fatty acid (BCFA), and butyrate concentrations were higher (P<0.05) when cats consumed the beef‐based diet. Our results suggest that the domestic cat serves as an appropriate model for large exotic felid species, but differences among the species exist. Decreased nutrient digestibility by tigers and jaguars should be considered when developing feeding recommendations for these species based on domestic cat data. Zoo Biol 29:432–448, 2010. © 2009 Wiley‐Liss, Inc.     

Intestinal sphingolipid excretion associated with feeding of phytohemagglutinin lectin (Phaseolus vulgaris) to germ-free and conventional rats

Intestinal sphingolipids of feces of germ-free and conventional rats were analyzed during the pair feeding of a complete defined diet containing phytohemagglutinin lectin (PHA) from red kidney beans (Phaseolus vulgaris) as 1% dietary protein in comparison to casein fed controls. Phytohemagglutinin in the diet increased the total fecal excretion of sphingomyelins (18-fold for germ-free and 20-fold for conventional rats), of non-acid glycosphingolipids (3.5-fold for germ-free and 9-fold for conventional rats) and also of the gangliosides (2.5-fold) for the germ-free rats compared to controls. For germ-free rats the increase of non-acid glycolipids was ascribed to an effect of the lectin strictly on the small intestinal mucosa, while for conventional rats an effect was seen also on the large intestinal mucosa. Increase of fecal gangliosides of germ-free rats was due mainly to an increased excretion ofN-acetylneuraminosyl-lactosylceramide, a ganglioside species restricted to epithelial cells of duodenum, of upper jejunum and of large intestines. The effects on glycolipid excretion observed in germ-free rats and the rather similar effects seen in conventional animals suggested that the influence of dietary PHA was due directly to effects elicited by PHA binding to the enterocyte brush border membrane and not to secondary effects induced by increase in the luminal microflora.     

Diet supplementation with beta-carotene improves the serum lipid profile in rats fed a cholesterol-enriched diet

The present study investigated the underlying mechanism associated with the hypocholesterolemic activity of beta-carotene by examining its effects on the serum lipid profile, fecal cholesterol excretion, and gene expression of the major receptors, enzymes, and transporters involved in cholesterol metabolism. Female Fischer rats were divided into three groups and were fed either a control or a hypercholesterolemic diet supplemented or not supplemented with 0.2 % beta-carotene. After 6 weeks of feeding, blood, livers, and feces were collected for analysis, and quantitative real-time polymerase chain reaction (qRT-PCR) was performed. Dietary supplementation with 0.2 % beta-carotene decreased serum total cholesterol, non-HDL cholesterol, the atherogenic index, and hepatic total lipid and cholesterol contents. These changes were accompanied by an increase in the total lipid and cholesterol contents excreted in the feces. The qRT-PCR analyses demonstrated that the hypercholesterolemic diet promoted a decrease in the gene expression of sterol regulatory element-binding protein 2, 3-hydroxy-3-methylglutaryl CoA reductase, and low-density lipoprotein receptor and an increase in the gene expression of peroxisome proliferator-activated receptor α and cholesterol-7a-hydroxylase. The expression of these genes and gene expression of ATP-binding cassette subfamily G transporters 5and 8 were unaffected by beta-carotene supplementation. In conclusion, the decrease in serum cholesterol and the elevation of fecal cholesterol obtained following beta-carotene administration indicate that this substance may decrease cholesterol absorption in the intestine and increase cholesterol excretion into the feces without a direct effect on the expression of cholesterol metabolism genes.     

Stimulation of fecal fat excretion and the disposal of protoporphyrin in a murine model for erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is characterized by toxic accumulation of the hydrophobic compound protoporphyrin (PP). Ferrochelatase-deficient (fch/fch) mice are an animal model for human EPP. Recently, we have demonstrated that the accumulation of another hydrophobic compound, unconjugated bilirubin, could effectively be treated by stimulation of fecal fat excretion. We investigated whether stimulation of fecal fat excretion enhanced the disposal of PP in fch/fch mice. Fch/fch mice were fed for 8 wk with a high-fat diet (16 wt% fat; control) or with the high-fat diet mixed with either a nonabsorbable fat (sucrose polyester) or the intestinal lipase inhibitor orlistat. The effects of the treatments on fecal excretion of fat and PP and on hepatic PP concentrations were compared with control diets. Fecal fat excretion in fch/fch mice on a high-fat diet was higher than in mice on a low-fat diet (+149%, P < 0.05). Sucrose polyesters and orlistat increased fecal fat excretion even more, up to sixfold of control values. However, none of the different treatments affected fecal PP excretion or hepatic PP concentration. Treatment of fch/fch mice with a high-fat diet, a nonabsorbable fat diet, or with orlistat increased the fecal excretion of fat but did not increase fecal PP excretion or decrease hepatic PP concentration. The present data indicate that accumulation of PP is not amenable to stimulation of fecal fat excretion.     

The influence of estrogen on hepatic cholesterol metabolism and biliary lipid secretion in rats fed fish oil

Both estrogen and dietary n-3 polyunsaturated fatty acids are known to be hypocholesterolemic, but appear to exert their effects by different mechanisms. In this study, the interaction between dietary fish oil (rich in n-3 polyunsaturated fatty acids) and estrogen in the regulation of hepatic cholesterol metabolism and biliary lipid secretion in rats was studied. Rats fed a low fat or a fish oil-supplemented diet for 21 days were injected with 17alpha-ethinyl estradiol (5 mg/kg body weight) or the vehicle only (control rats) once per day for 3 consecutive days. Estrogen-treatment led to a marked reduction in plasma cholesterol levels in fish oil-fed rats, which was greater than that observed with either estrogen or dietary fish oil alone. The expression of mRNA for cholesterol 7alpha-hydroxylase was decreased by estrogen in rats fed a low fat or a fish oil-supplemented diet, while the output of cholesterol (micromol/h/kg b.wt.) in the bile was unchanged in both groups. Cholesterol levels in the liver were increased by estrogen in rats given either diet, but there was a significant shift from cholesterol esterification to cholesteryl ester hydrolysis only in the fish oil-fed animals. Estrogen increased the concentration of cholesterol (micromol/ml) in the bile in rats fed the fish oil, but not the low fat diet. However, the cholesterol saturation index was unaffected. The output and concentration of total bile acid was also unaffected, but changes in the distribution of the individual bile acids were observed with estrogen treatment in both low fat and fish oil-fed groups. These results show that interaction between estrogen-treatment and dietary n-3 polyunsaturated fatty acids causes changes in hepatic cholesterol metabolism and biliary lipid secretion in rats, but does not increase the excretion of cholesterol from the body.     

Transit time and digestibility of two experimental diets in the maned wolf (Chrysocyon brachyurus) and domestic dog (Canis lupus)

Recent research involving nutritional management of clinical disease secondary to cystinuria in captive maned wolves (Chrysocyon brachyurus) in the United States resulted in the production of a commercially manufactured maintenance diet and subsequently, a further modified experimental diet. These two diets differed only in their protein sources and sodium concentrations. The purpose of this study was to further investigate these diets by determining their digestibility and transit time in maned wolves, and also to compare these results to the digestibility and transit time of the diets in domestic dogs. The experiment consisted of two diets (maned wolf commercial maintenance diet and experimental diet) and two species (maned wolf and domestic dog [beagle]) arranged as a 2 × 2 factorial design. For the transit time study, titanium dioxide (TiO₂, 5 g/kg diet) was administered as a pulse dose and total collection of feces was carried out for 50 hr. There was no effect of diet or species on initial Ti recovery time (IRT), the amount of Ti recovered at IRT, or the time to reach 50% of Ti excretion in the feces. Maned wolves had lower total percent recovery (P<0.01) of Ti than dogs and shorter time to last recovery of Ti in the feces (P<0.05), however, marker excretion in the maned wolves may not have been complete. For the digestibility study, in which chromic oxide was used as a marker, fecal samples were collected on 2 consecutive days immediately after 12 days of being fed the diets and then analyzed for dry matter, energy, protein, and minerals. Crude protein, calcium, phosphorus, and zinc apparent digestibilities were unaffected by species or diet (P>0.05). Apparent digestibility of dry matter (P<0.05) and energy (P<0.01) were higher in the experimental diet and in the dogs. Both dogs and maned wolves fed the maintenance diet exhibited a greater apparent retention of copper, iron, and magnesium (P<0.01). Dogs had a higher apparent retention of magnesium and sodium than the maned wolves. Zoo Biol 0:1–13, 2006. © 2006 Wiley‐Liss, Inc.