Increase of bile acids synthesis and excretion caused by taurine administration prevents the ovariectomy-induced increase in cholesterol concentrations in the serum low-density lipoprotein fraction of Wistar rats

Dietary methionine increased the lipid accumulation in juvenile tiger puffer Takifugu rubripes

Methionine (Met) is one of the most important amino acids in fish feed. The effects of dietary Met on lipid deposition in fish varied a lot among different studies. The present study was aimed at investigating the effects of dietary Met supplementation on the lipid accumulation in tiger puffer, which have a unique lipid storage pattern. Crystalline L-Met was supplemented to a low-fishmeal control diet to obtain two experimental diets with a low (1.1% of dry weight, L-MET) or high Met level (1.6% of dry weight, H-MET). A 67-day feeding trial was conducted with juvenile tiger puffer (average initial weight, 13.83 g). Each diet was fed to triplicate tanks (30 fish in each tank). The results showed that the total lipid contents in whole-body and liver significantly increased with increasing dietary Met levels. The hepatosomatic index, weight gain, and total bile acid content in serum showed similar patterns in response to dietary Met treatments, while the lipid content in muscle was not affected. The hepatic contents of 18-carbon fatty acids were elevated by dietary Met supplementation. The Hepatic mRNA expression of lipogenetic gene such as FAS, GPAT, PPARγ, ACLY, and SCD1 was down-regulated, while the gene expression of lipolytic genes ACOX1 and HSL, as well as that of ApoB100, were up-regulated by increasing dietary Met levels. The hepatic lipidomics of experimental fish was also analyzed. In conclusion, increasing dietary Met levels (0.61%, 1.10%, and 1.60%) increased the hepatic lipid accumulation in tiger puffer. The mechanisms involved warrant further studies.

Effects of sanshoamides and capsaicinoids on plasma and liver lipid metabolism in hyperlipidemic rats

The objective of this study was to determine the effects of sanshoamides and capsaiciniods on plasma and liver lipid levels and the mRNA expression levels of key receptors involved in cholesterol metabolism in hyperlipidemic rats. A total of 56 three-week-old female Sprague-Dawley rats were assigned to 7 treatment groups based on initial body weight (n = 8 rats per group). With certain combinations of sanshoamides and capsaicinoids significantly increased food intake, reduced lipid levels in blood and liver, improved histological characteristics of a fatty liver, down regulated mRNA expression levels of cholesterol 7-alpha-hydroxylase (CYP7A1), 3-hydroxyl-3-methylglutary CoA (HMG-CoA) and Farnesoid X Receptor (FXR) in liver and apical sodium-dependent bile acid transporter, Ileal Bile Acid Binding Protein and FXR in the ileum in hyperlipidemic rats. These results indicated that dietary supplementation with sanshoamides and capsaicinoids reduced blood lipid levels and improved cholesterol metabolism in hyperlipidemic rats.

Serum metabolomics analysis of rat after intragastric infusion of Pu-erh theabrownin

BACKGROUND

The aim was to study the effects of Pu-erh theabrownin (TB) (Mw  > 50 kDa) on the metabolism of rat serum by nuclear magnetic resonance (NMR)-based metabolomics and identify candidate marker metabolites associated with Pu-erh TB, and thus provide fundamental information for a better understanding of the metabolism of Pu-erh tea in animals.

RESULTS

TB infusion induced different changes in endogenous serum metabolites depending on the type of diet. Compared with the control group, the TB infusion group showed significantly reduced serum glycine and choline levels, as well as significantly increased taurine, carnitine and high-density lipoprotein (all P < 0.05). Compared with the high-lipid group, the high-lipid TB infusion group exhibited significantly reduced low-density lipoprotein and acetate levels, as well as significantly increased inositol, carnitine and glycine levels (all P < 0.05).

CONCLUSION

Examination of the variations of these differential expressed metabolites and their individual functions revealed that the TB extract accelerated lipid catabolism in rats and might affect glucose metabolism. Of these, carnitine level significantly increased after intragastric infusion of TB regardless of the type of diet, and activities of carnitine palmitoyltransferases I and II changed significantly, suggesting carnitine may be a candidate serum marker for tracking the metabolism of TB in rats. © 2015 Society of Chemical Industry.

Methionine limitation results in increased hepatic FAS activity, higher liver 18:1 to 18:0 fatty acid ratio and hepatic TAG accumulation in Atlantic salmon, Salmo salar

The current experiment aimed to study whether interactions with lipid metabolism possibly might explain the relative increased liver weight obtained in fish fed sub-optimal methionine levels. A basal diet based on a blend of plant proteins which is low in methionine (1.6 g Met/16 g N) was compared to a methionine adequate diet (2.2 g Met/16 g N) prepared by adding DL-methionine (2.4 g/kg) to the basal diet in the expense of wheat grain. Fish oil was used as the lipid source. The diets were balanced in all nutrients except methionine. The diets were fed to Atlantic salmon (500 g BW) for a period of 3 months. Feed intake did not differ, rendering the intake of all nutrients except methionine equal. Fish fed the low methionine diet had an increased liver size relative to body weight, indicating fat deposition in the liver. Fish given the sub-optimal methionine diet showed about six times higher fatty acid synthase (FAS) activity as compared to the fish fed the adequate methionine diet, indicating a higher de novo lipogenesis. A significant rise in the liver 18:1 to 18:0 fatty acid ratios also supported storage of lipids over fatty acid oxidation. Indeed, methionine limitation resulted in significantly higher TAG concentrations in the liver. Sub-optimal dietary methionine also resulted in lower hepatic taurine concentrations and the total bile acids concentrations were reduced in faeces and tended to be reduced in plasma. Taken together, our data show that salmon fed sub-optimal methionine levels had increased relative liver weight and developed signs commonly described in the early stage of non-alcoholic fatty liver disease in rodent models (increased FAS activity, changed fatty acid ratios and TAG accumulation).

The mechanism of the cholesterol-lowering effect of water-insoluble fish protein in ovariectomised rats

The purpose of the present study was to investigate whether water-insoluble fish protein (IFP) from Alaska pollock (Theragra chalcogramma) prevents hypercholesterolaemia induced by ovarian hormone deficiency. Wistar female rats, aged 6 months, were subjected to sham-operation or ovariectomy, and fed a cholesterol-free diet containing casein or IPF as a protein source for 28 d. Body-weight gain and food intake increased in the ovariectomised rats as compared with the sham-operated rats. Plasma total cholesterol concentration was decreased and faecal bile acid excretion was increased by IFP in the ovariectomised rats, but not in the sham-operated rats. Plasma homocysteine concentration was decreased by IFP in the ovariectomised rats, but not in the sham-operated rats. Liver lipids and liver cholesterol concentrations were increased and cholesterol 7alpha-hydroxylase (CYP7A1) activity was decreased by ovariectomy, but not by diet. Bile acid content and the ratio of cholic acid groups to chenodeoxycholic acid groups in bile were increased by ovariectomy, but decreased by IFP. Bile acid content in the small intestine was increased by IFP in the ovariectomised rats, but not in the sham-operated rats. 3-Hydroxy-3-methylglutaryl-CoA reductase and microsomal TAG transfer protein mRNA levels were decreased by ovariectomy and IFP, whereas LDL-receptor mRNA level was decreased by ovariectomy but unaffected by diet. Thus, the preventive effect of IFP on the ovarian hormone deficiency-associated increase in plasma cholesterol concentration seems to be mediated by accelerated faecal excretion of bile acids, coupled with an increase in the intestinal pool of bile acids.

Hypocholesterolemic effects of microbial protease-resistant fraction of Katsuobushi in ovariectomized rats depend on the both oil and undigested protein

The purpose of this study was to examine which component in the microbial protease-resistant fraction of Katsuobushi (KBR), smoke-dried bonito, is hypocholesterolemic in ovariectomized rats (OVX-rats). KBR contains two major components: oil and protease-resistant protein. Oil extracted from KBR (EX) was rich in palmitic, oleic and docosahexaenoic acids. OVX-rats were fed one of the following diets for 28 d: diets containing casein as the protein source (C or C+EX diet), a diet containing KBR as the protein source (KBR diet) or diets containing degreased KBR as the protein source (DF/KBR or DF/KBR+EX diet). The C and DF/KBR diets contained soybean oil as the oil source. In the C+EX, KBR and DF/KBR+EX diets, soybean oil was replaced by oil extracted from KBR (EX). Plasma total- and low density lipoprotein-cholesterol concentrations in the C+EX, KBR and DF/KBR+EX groups, but not in the DF/KBR group, were significantly lower than that in the C group. Fecal bile acid excretion was significantly greater in the C+EX, KBR, DF/KBR and DF/KBR+EX groups in comparison to the C group, whereas excretion in the KBR and DF/KBR+EX groups was significantly greater than in the C+EX and DF/KBR groups. Cholesterol 7alpha-hydroxylase activity was higher in the C+EX, KBR, DF/KBR and DF/KBR+EX groups than the C group. In OVX-rats fed C, C+EX or KBR for 28 d, bile acid flux into the small intestine increased in KBR and C+EX groups in comparison to the C group. The hypocholesterolemic effect of KBR in OVX-rats reflected in increased fecal bile acid excretion may be mediated by increased bile acid flux caused by EX and the binding of bile acids by protease-resistant proteins.

Hypolipidaemic effect of maize starch with different amylose content in ovariectomized rats depends on intake amount of resistant starch

The effect of amylose content on digestibility of starch in the small intestine and on the concentration of plasma lipid were studied in ileorectostomized rats and in ovariectomized rats, respectively. Seven kinds of starch with different amylose content (0, 27, 54, 62, 76, 79, 86 %) were used as test starch, which contained 0·4, 5·6, 37·1, 40·2, 45·6, 36·9 and 36·1 % resistant starch (RS), respectively. Rats were fed one of test diets containing 30 % test starch with different amylose content for 14 d in ileorectostomized and for 21 d in ovariectomized rats. Food intake was not significantly different among the groups. In ileorectostomized rats, the small intestinal starch digestibility decreased with increasing intakes of amylose and RS. In ovariectomized rats, body weight gain was lower on the higher amylose maize starch diets. The concentrations of plasma TAG and cholesterol decreased with increasing intake of RS. The concentrations of liver total lipids and TAG decreased with increasing intake of RS, but that of liver cholesterol did not. There was significant positive correlation between the level of sterol regulatory element-binding protein-1c mRNA and concentration of liver TAG. Total SCFA amount in the caecum increased logarithmically with increasing dry weight of caecal contents. The amount of bile acids in the small intestinal content and the excretions of bile acids and neutral steroids in faeces increased with increasing RS intake. These results show that starch rich in RS is more effective in preventing ovarian hormone deficiency-induced hyperlipidaemia.

Metabonomic study on the toxicity of Hei-Shun-Pian, the processed lateral root of Aconitum carmichaelii Debx. (Ranunculaceae)

The purpose of this paper was to study the effects of Hei-Shun-Pian, the processed lateral root of Aconitum carmichaelii Debx. (Ranunculaceae), on the metabolic profile of rats, to discuss the mechanism of toxicology and to find out the potential biomarkers of the toxic effects. Twenty male Wistar rats were divided into four groups (n=5) and each group were administered orally with the decoction of Hei-Shun-Pian (88.1g/kg per day, 35.6g/kg per day, 17.6g/kg per day) or equal volume of drinking water respectively for 14 days. Urine of every 24-h and the plasma of the last day were collected for NMR experiments, and then analyzed by multivariate analysis methods. Decreases in urinary excretion of taurine and trimethylamine-N-oxide (TMAO) and increases in urinary levels of citrate, 2-oxoglutarate (2-OG), succinate and hippurate were observed in the high and medium dosed groups at the early stage of the dosing period. Taurine level increased at the later stage of the dosing period to the normal value, and then even to a value higher than that of the control group at the end of the experiment. No metabolic differences were observed between low dosed and control groups until the later stage of the dosing period when a slight increase in urinary taurine level was observed, suggesting a cumulative effect. These results suggest the toxic effect of Hei-Shun-Pian on rat heart in a dose dependent manner.

Heat-moisture treatment of high-amylose corn starch increases dietary fiber content and lowers plasma cholesterol in ovariectomized rats

The effect of dietary high-amylose corn starch (HACS) of varying dietary fiber (DF) content on plasma cholesterol was examined in ovariectomized (OVX) rats. Gelatinized normal corn starch (G-CS) was used as a reference. OVX rats were fed a fiber-free purified diet containing G-CS, HACS, gelatinized high-amylose corn starch (G-HACS), or heat-moisture treated HACS (HM-HACS) at 400 g starch/kg diet for 21 d. The DF content of G-CS, HACS, G-HACS, and HM-HACS measured by the AOAC method was 0.1, 19.3, 2.4, and 64.5 g/100 g, respectively. The dry weight of cecal contents, cecal wall weight, the amount of short chain fatty acids in cecal contents, the amount of bile acids in small intestinal contents, and fecal excretion of neutral sterols increased logarithmically with increasing DF, while total plasma cholesterol concentration decreased. On the other hand, hepatic CYP7A1 activity, fecal dry weight, and fecal excretion of bile acids increased linearly with increasing DF, while body weight gain decreased. The hypocholesterolemic effect of HACS in OVX-rats appeared to be more effective by heat-moisture treatment.

Effects of a soluble fraction of soybean on lipid profiles in ovariectomized rats fed a cholesterolemic diet

The increases in serum lipid profiles at the onset of menopause are regarded as a risk factor for cardiovascular disease. This study was designed to clarify the effects of a dried aqueous soybean extract and ovariectomy on lipid parameters in rats fed with cholesterolemic diet. Twenty-four 9-week-old female Sprague-Dawley rats were divided into two groups of 12 each and either sham-operated or ovariectomized. The ovariectomized and sham groups were then subdivided into groups of six and fed a semipurified casein-based diet (control diet) or the same diet containing dried soybean extract (0.5%) at the expense of sucrose (experimental diet). Total isoflavone content was 4.52 mg/g of soy extract. Ovariectomized groups showed significantly greater weight gain and food intake than sham groups, while uterus weight was markedly lower in ovariectomized groups. Although ovariectomy significantly increased the concentration of serum triacylglycerol, the concentration of serum total cholesterol was not affected by the operation. Soybean extract restored the concentration of serum triacylglycerol in the ovariectomized groups to the level observed in the sham groups. On the other hand, liver cholesterol levels were significantly higher in the ovariectomized groups compared to the sham group, without effects of the diet. This study suggests that soybean extract supplementation modulates the level of serum triacylglycerol induced by ovariectomy in rats, and furthers the possibility that dietary cholesterol may be a crucial factor in determining liver cholesterol in the presence of ovarian hormone deficiency.

Lowering effect of an isoflavone-rich fermented soybean extract on the serum cholesterol concentrations in female rats, with or without ovariectomy, but not in male rats

We examined the effect of administering an isoflavone-rich fermented soybean extract (FSBE) on the serum cholesterol concentrations in male rats and in intact and ovariectomized (OVX) female rats. Dietary FSBE decreased the serum cholesterol concentrations in intact female and OVX rats, but did not affect the concentrations in male rats. Dietary FSBE increased the hepatic total and esterified cholesterol contents in the intact female rats, but decreased them in the OVX rats. This hypocholesterolemic effect was not a simple estrogenic effect because it has appeared in some reports that estrogen administration decreased serum cholesterol both male and female rats. Dietary FSBE increased the hepatic low-density lipoprotein receptor (LDLR) gene expression in the intact female rats as has previously been reported from many studies, but did not affect that of the OVX rats. Further investigation is needed into the hypocholesterolemic mechanism of FSBE.

Retrograded Tapioca Starch Prevents Ovarian Hormone Deficiency-Induced Hypercholesterolemia

The purpose of this study was to examine whether retrograded tapioca starch (RS3-tapioca) prevents ovarian hormone deficiency-induced hypercholesterolemia. Six-month-old Wistar female rats were subjected to sham-operation or ovariectomy, and fed a cholesterol-free purified diet with or without RS3-tapioca (150 g/kg diet) instead of digestible cornstarch for 28 d. Body weight gain and food intake increased in ovariectomized rats (OVX-rats). Plasma total cholesterol concentration was lowered by RS3-tapioca in OVX rats, but not in sham-operated rats. Liver lipids increased in OVX-rats, but liver cholesterol concentration was not affected by ovariectomy and RS3-tapioca. CYP7A1 activity, small intestinal and cecal bile acid content, and fecal bile acid excretion were increased by RS3-tapioca. The ratio of cholic acid groups to chenodeoxycholic acid groups in the bile acid of the small intestine was increased by RS3-tapioca. Thus, the preventive effect of RS3-tapioca on the ovarian hormone deficiency-associated increase in plasma cholesterol concentration appears to be mediated by accelerated fecal excretion of bile acid and an increase in the intestinal pool of bile acid.