Bile acid metabolism in rats fed two levels of corn oil and brans of oat, rye and barley and sugar beet fiber.

High concentrations of fecal bile acids are associated with a higher incidence of colon cancer. Dietary changes that alter bile acid metabolism are therefore of interest. Here, we report the effect of feeding diets containing four fiber sources and two fat levels for 7 wk on bile acid excretion and small intestinal bile acids (an index of pool size) in rats. The fiber sources were oat bran, rye bran, barley bran and sugar beet fiber. Fiber-containing diets were 8% dietary fiber and contained either 5 or 20% corn oil. All fiber sources caused significantly greater fecal output compared with the fiber-free basal diet. All fiber sources also resulted in significantly (P less than 0.05) lower fecal bile acid concentration compared with the fiber-free basal diet. Only rye bran resulted in significantly (P less than 0.05) higher total fecal bile acid excretion. Oat bran resulted in a slightly but significantly (P less than 0.05) higher quantity of small intestine bile acids compared with the other diets. Dietary fat level had no significant effect on fecal bile acid concentration or excretion or quantity of small intestinal bile acids. We conclude that all four fiber sources tested resulted in lower fecal bile acid concentration, by effectively causing greater fecal mass. Changes in dietary fat level as corn oil had no effect on fecal bile acids.     

The effect of dietary fibre on bile acid metabolism in rats

1. Forty-eight male rats were fed sequentially for 14 d periods on diets containing different fibre contents. 2. One of the high-fibre diets was a commercial pelleted diet. The other was a low-fibre diet supplemented with 200 g wheat bran/kg. 3. At the end of each feeding period eight rats were killed. Liver microsomal cholesterol 7 alpha-hydroxylase (EC 1.14.1.-) activity and bile acid content of small intestine and colon were determined. 4. The different diets did not significantly alter the total intestinal bile acids, but affected the distribution and qualitative pattern in the colon and small intestine. 5. On the high-fibre diets deoxycholate, and hyodeoxycholate tended to be increased. 6. On the low-fibre diets the alpha, beta- and omega-muricholic acids tended to be increased. 7. Liver microsomal cholesterol 7 alpha-hydroxylase activity was lower in rats on the low-fibre and bran-supplemented low-fibre diets compared with that in rats fed on the commercial pelleted diet.     

Effects of ethanol on bile acid and cholesterol metabolism.

The effects of ethanol on plasma lipid and lipoprotein concentrations and on the fecal excretion of neutral sterols and bile acids were studied in three patients with ethanol-induced hyperlipidemia and in four normolipidemic men. In the three patients, plasma triglyceride and cholesterol concentrations were much higher with ethanol than during periods when ethanol was isocalorically substituted with either carbohydrate or both fat and carbohydrate. In the normolipidemic subjects, plasma lipids especially in very low density lipoproteins, were higher with ethanol consumption only in comparison with a balanced diet but not when compared with carbohydrate-rich diets. Triglyceride enrichment of low density lipoproteins occurred uniformly with ethanol. Total sterol excretion, measured by isotope dilution and chemical assay, was similar during ethanol and control periods in two out of the three hyperlipidemic subjects. However, the proportion of bile acids was increased in all three hyperlipidemic subjects but in only one normolipidemic subject while on ethanol. Since cholesterol turnover did not appear to be necessarily influenced by ethanol, as judged either by total endogenous sterol excretion or from the slope of the plasma cholesterol specific radioactivity-time curve, the ethanol-induced increase in bile acid excretion amy not be analogous to other clinical disorders in which increased bile acid excretion and hypertriglyceridemia are associated with raised sterol production.     

Effects of excess dietary tyrosine on cholesterol, bile acid metabolism and mixed-function oxidase system in rats

Excess dietary tyrosine (12%) caused hypercholesterolemia in male Wistar rats and significantly increased cytochrome P-450 and b5 contents. Bile flow and biliary output of total bile acids were significantly increased in rats fed this diet. Biliary output of cholesterol was not significantly altered, whereas that of taurocholic acid was significantly increased. Excess dietary tyrosine significantly decreased the fecal excretion of neutral steroids, whereas total steroid excretion was not significantly changed. The present results indicate that excess dietary tyrosine causes hypercholesterolemia without modifying the fecal total steroid excretion, thus supporting our previous hypothesis that stimulated synthesis of cholesterol is a main reason why excess dietary tyrosine leads to hypercholesterolemia.     

Effect of wheat flour, Bengal gram flour and corn flour on lipid metabolism in rats

Male albino rats were fed on respective diets of wheat flour, Bengal gram flour and corn flour for 8 weeks at the 59% level. It was observed that the increase in weight after wheat flour and Bengal gram flour feeding was 6.8 and 12.0% respectively and that the decrease after corn flour feeding was 5.2% as compared to the control animals on sucrose diet. Serum cholesterol and liver cholesterol levels were significantly (p less than 0.01) decreased after wheat flour, Bengal gram flour and corn flour feeding.     

Influence of cocoa butter on cholesterol metabolism in rats: Comparison with corn oil,coconut oil and palm kernel oil

Rat were fed a semipurified diet containing 14% fat for 5 weeks. The fats compared were corn oil (CO), coconut oil (CNO), palm kernel oil (PKO) and cocoa butter (CB). Rats fed CO gained more weight than the others. Serum cholesterol levels were generally highest in rats fed PKO and liver cholesterol levels were highest in rats fed CO. Liver triglycerides were also highest in rats fed CO. Cholesterol absorption was highest in rats fed CO (62.1%) and PKO (62.7%) and lowest in those fed CNO (52.9%) and CB (50.9%). Cholesterogenesis in liver slices was assayed usign 1-¹⁴C acetate and 2-¹⁴C-mevalonate. When acetate was the substrate, liver slices from rats fed CB incorporated more isotope into cholesterol than the other three groups. Liver slices from rats fed CO or CB incorporated more mevalonate into cholesterol than did slices from rats fed either CNO or PKO. The effect of CB on cholesterol metabolism belies its low iodine value and may be due to triglyceride structure or the percentage of long-chain saturated fatty acids present in this fat.     

Digestibility of cocoa butter and corn oil and their influence on fatty acid distribution in rats

The comparative bioavailability of cocoa butter (a predominantly saturated fat) and corn oil (a predominantly unsaturated fat) was determined in male Sprague-Dawley rats by analysis of total fecal lipids following ad libitum feeding of purified diets containing 5, 10 and 20% cocoa butter or corn oil for 2 wk. Fecal lipid elimination was significantly increased (P less than 0.05) in each cocoa butter group when compared with the corresponding corn oil group, resulting in lower digestibility coefficients for cocoa butter (59-72%) than for corn oil (93-97%). Body weight gain and food intake data were similar among all treatment groups. Fecal fatty acid profiles in rats fed corn oil diets consisted primarily of 27-34% palmitic acid (16:0), 22-32% stearic acid (18:0) and 25-37% oleic acid (18:1). Palmitic, oleic and linoleic acids were also the primary fatty acids stored in epididymal fat tissue from corn oil-fed rats. In contrast, fecal fatty acids in animals fed cocoa butter diets consisted of 31-37% palmitic acid and 58-64% stearic acid; oleic acid was the major fatty acid stored in epididymal fat tissue. These results indicate that the decreased digestibility of cocoa butter is largely a result of its fatty acid composition. This reduced bioavailability of cocoa butter may be at least partially responsible for its previously described neutral effect on serum cholesterol.     

Effects of dietary selenium and fish oil (MaxEPA) on arachidonic acid metabolism and hemostatic function in rats

This study investigated whether hemostatic function can be modified by both the consumption of fish oil and the level of dietary selenium. Male Sprague-Dawley rats were fed for 8 wk semipurified diets containing 7% corn oil (by wt) or 5.5% fish oil (MaxEPA) plus 1.5% corn oil with or without selenium supplementation. Consumption of the four diets caused no difference in weight gain, food intake or plasma malondialdehyde content. The selenium-supplemented rats had significantly higher levels of selenium and glutathione peroxidase activity in plasma. Fish oil feeding decreased ADP-induced platelet aggregation and increased bleeding time. The level of dietary selenium and type of oil interacted to influence the production of 6-keto-prostaglandin F1 alpha: more was produced when corn oil was fed in the selenium-deficient diets. These data suggest that the effect of dietary selenium on hemostatic function and the production of eicosanoids is minor.     

Effect of dietary levels of corn oil on maternal arachidonic acid synthesis and fatty acid composition in lactating rats

OBJECTIVE: We examined the effect of different amounts of dietary corn oil rich in linoleic acid (LA) on the endogenous synthesis of arachidonic acid (AA), uptake of its precursor LA, and fatty acid composition of tissues involved in the supply of long-chain polyunsaturated fatty acids for milk synthesis. METHODS: Female Sprague Dawley rats received one of the following diets during pregnancy and lactation: a low-lipid diet (LLD; 2%), an adequate-lipid diet (ALD; 5%), or a high-lipid diet (HLD; 10%). Lipids were provided by corn oil. On day 12 of lactation we measured the endogenous synthesis of AA and quantified the conversion of (13)C-LA to (13)C-AA and the metabolic fate of (13)C-LA from all dietary groups. RESULTS: The LLD rats demonstrated larger amounts of endogenous synthesis of (13)C-AA and more dietary (13)C-LA transferred to the mammary gland (MG) than HLD rats during lactation. The proportion of medium-chain fatty acids was higher in the MG, milk clot, and liver of LLD than of HLD rats. Daily volume and 24-h yield of lipids and energy were lower in LLD rats than in HLD rats. Measurements of milk composition demonstrated that fat concentration significantly increased as lipid concentration increased in the diet. CONCLUSION: These results suggest that maternal adaptations used to compensate for diets deficient in long-chain polyunsaturated fatty acids include increased endogenous synthesis of AA and elevated uptake of LA in the MG and increased synthesis of medium-chain polyunsaturated fatty acids. It appears that the MG and liver participate together for AA synthesis for milk when this fatty acid is not provided in the diet.     

Effects of resistant potato starch on cholesterol and bile acid metabolism in the rat

This study examines the effects of two types of resistant starch (RS), raw starch from uncooked potatoes and retrograded starch in the form of cooked and cooled potatoes, on cholesterol and bile acid metabolism in rats. Groups of 8 male Wistar rats were fed a semipurified diet containing 15% cellulose, freeze-dried raw potatoes, or freeze-dried cooked potatoes for four weeks. Serum cholesterol, liver cholesterol, and fecal steroid excretion were determined. Serum cholesterol was significantly higher and liver cholesterol was significantly lower in response to the cooked potato diet compared to the cellulose or raw potato diet. Total steroid excretion was significantly higher in rats fed the cooked potato diet (26.31 mg/d) compared to those fed the cellulose or raw potato diet (14.27 mg/d and 16.81 mg/d, respectively). Daily total bile acid excretion was significantly different among the three groups, with highest excretion seen in rats fed cooked potatoes. High daily excretion of lithocholic acid and hyodeoxycholic acid was observed in rats fed cooked potatoes. These results suggest that changes in the cecal microflora and in the production, pool size, and excretion of chenodeoxycholic acid and its derivatives may be responsible for alterations in cholesterol and bile acid metabolism observed with resistant starch feeding.     

Effects of some xenobiotics on ascorbic acid metabolism in rats

The administration of xenobiotics, PCB, DDT, or aminopyrine to rats causes a marked increase in urinary excretion of ascorbic acid and in various tissue levels of ascorbic acid. When rats were fed diet containing 200 ppm PCB or 500 ppm DDT (14 days), the incorporations from D-(U-14C) glucose into ascorbic acid in liver were significantly increased. The dietary addition of 200 ppm PCB, 500 ppm DDT, 2,000 ppm pentobarbital or 3,000 ppm chloretone caused a significant increase in the activity of hepatic UDPglucose dehydrogenase, but did not affect the activity of hepatic L-gulonolactone oxidase. Good correlation between the liver level of ascorbic acid and the activity of hepatic UDPglucose dehydrogenase was observed. Subsequently, in rats fed the basal diet (30% casein diet) or the diet containing 200 ppm PCB, the specific activities of ascorbic acid in urine and in various tissues were measured 6 hours, 12 hours and 24 hours after the oral administration of L-(l-14C)ascorbic acid. Dietary PCB accelerated the disappearances of radioactivities in ascorbic acid in urine and various tissues, that is, shortened the half lives of radioactivities in ascorbic acid. It is likely that the administration of xenobiotics, such as PCB or DDT, to rats increases the biosynthesis of ascorbic acid and accelerates concomitantly the turnover of ascorbic acid in body.     

大蒜油及大鼠周龄和性别对正己烷体内代谢的影响

目的 探讨大蒜油及周龄、性别对正己烷在大鼠体内代谢的影响.方法 以Wistar大鼠为实验动物,(1)灌胃染毒:正己烷组(3000 mg/kg正己烷),大蒜油干预组(染毒前1 h予80 mg/kg大蒜油灌胃),8、12、16、20、24、28、32 h断尾取血.(2)腹腔注射染毒:正己烷组(1000 mg/kg正己烷),大蒜油干预组(染毒药前1 h予80 mg/kg大蒜油灌胃),8、12、16、20、24、28 h断尾取血.(3)6、8、10周龄(均为7只)雄性大鼠予正己烷3000 mg/kg灌胃,染毒后16、20、24 h断尾取血.(4)8周龄大鼠雌、雄各7只,予正己烷3000 mg/kg灌胃,染毒后16、20、24、28 h断尾取血.气相色谱法测定血清中2,5-己二酮浓度,比较给和不给大蒜油、不同周龄、不同性别大鼠血清中2,5-己二酮浓度.结果 (1)灌胃染毒:正己烷组、大蒜油干预组血清中2,5-己二酮浓度分别在20和24 h达到峰值,分别为19.2和12.3μg/ml,在峰值及之前时间点大蒜油干预组血清中2,5-己二酮浓度明显降低,但峰值后的消除过程明显减缓.(2)腹腔注射染毒:大蒜油对血清中2,5-己二酮浓度的影响与正己烷灌胃途径基本相同,两组分别在12和16 h达到峰值,分别为15.0和6.7 μg/ml.(3)周龄:16 h时6、8、10周龄大鼠血清中2,5-己二酮浓度分别为25.5、15.0、12.8μg/ml,8、10周龄与6周龄的差异有统计学意义(P＜0.05或P＜0.01);20 h时6、8、10周龄大鼠血清中2,5-己二酮浓度分别为24.7、18.3、15.0 μg/ml,10周龄与6周龄的差异有统计学意义(P＜0.05);24 h时6、8、10周龄大鼠血清中2,5-己二酮浓度分别为11.0、14.7、8.1 μg/ml,10周龄与8周龄的差异有统计学意义(P＜0.05).(4)性别:16 h时雄性、雌性大鼠血清中2,5-己二酮浓度分别为22.5、17.2 μg/ml,差异有统计学意义(P＜0.05);在20、24、28 h雄性、雌性大鼠血清中2,5-己二酮浓度分别为27.6、22.9μg/ml,24.6、19.1 μg/ml,19.1、13.8μg/ml,不同性别间的差异均无统计学意义(P＞0.05).结论 大蒜油可明显减少正己烷在大鼠体内代谢物2,5-己二酮的生成量;低周龄的动物正己烷的代谢能力高于高周龄的动物.

Abstract：

Objective To investigate effects of garlic oil (GO),age and sex on n-hexane metabolism in rats. Methods The Wistar rats were used as experimental animals. (1) Intragastric administration: nhexane group (3000 mg/kg n-hexane),GO treated group (80 mg/kg GO ig. an hour earlier than 3000 mg/kg n-hexane), then blood was taken from tails of rats at 8, 12, 16, 20, 24, 28, 32 h points after n-hexane administration. (2)Intraperitoneal injection: n-hexane group ( 1000 mg/kg n-hexane), GO treated group (80 mg/kg GO ig. an hour earlier than 1000 mg/kg n-hexane), then took blood was taken from tails of rats at 8, 12,16, 20, 24, 28 h points after n-hexane injection. (3) 7 rats each group of 6, 8, 10 weeks age were administrated by 3000 mg/kg n-hexane intragastrically, then were taken blood from tails at 16, 20, 24 h points after administration.(4) 7 male and 7 female rats of 8 weeks age were administrated by 3000 mg/kg n-hexane intragastrically, then were taken blood from tails at 16, 20, 24, 28 h points after administration. The gas chromatography was used to determine the metabolite 2, 5-hexanedione concentration of n-hexane in serum and 2, 5-hexanedione concentration was compared between GO and no GO treated rats, different ages and different sexes. Results ( 1 )Intragastric administration: 2, 5-hexanedione concentrations in serum of n-hexane group and GO treated group had the peak 19.2 and 12.3 μg/ml at 20 h and 24 h points. Compared with nhexane group, the serum 2, 5-hexanedione concentration of GO treated group was lower at time points prior to peak and 2, 5-hexanedione eliminating process was slower after peak. (2) Intraperitoneal injection: effects of GO on the serum 2, 5-hexanedione concentrations was very similar to intragastric administration, 2, 5-hexanedione concentrations in serum of n-hexane group and GO treated group had the peak 15.0 and 6.7μg/ml at 12 h and 16 h points.(3) Comparison of the serum 2, 5-hexanedione concentrations of different weeks age rats: The serum 2, 5-hexanedione concentrations of 6, 8, 10 weeks age rats were 25.5, 15.0, 12.8μg/ml each (8, 10 weeks age significantly lower than 6 weeks age) at 16 h point; at 20 h point, they were 24.7, 18.3, 15.0 μg/ml each ( 10 weeks age significantly lower than 6 weeks age); at 24 h point, they were 11.0, 14.7, 8.1 μg/ml each (10 weeks age significantly lower than 8 weeks age). (4) Comparisons of the serum 2, 5-hexanedione concentrations of different sex rats: the serum 2, 5-hexanedione concentrations of male and female rats were 22.5, 17.2 μg/ml each at 16 h point (different significantly); at 20, 24, 28 hpoints, they were 27.6, 22.9 μg/ml, 24.6,19.1 μg/ml, 19.1, 13.8 μg/ml each (different non-significantly).Conclusion GO reduces production of 2, 5-hexanedione in serum generated by n-hexane in rats; the metabolic capacity of low age rats on n-hexane is stronger than high age ones.     

Effects of guar gum and wheat bran on lipid metabolism of rats.

The effects of guar gum and wheat bran on blood and liver lipid levels of rats were measured. In experiment 1, rats were fed ad libitum a 55% sucrose diet containing 0, 15 or 25% wheat bran for 3 weeks. Postprandial plasma triglyceride, liver triglyceride and liver cholesterol values in rats fed the sucrose diet with wheat bran were significantly lower than values for rats fed the diet without wheat bran. Neither fasting plasma triglyceride nor cholesterol values were altered by wheat bran. In experiment 2, rats were meal-fed one of four experimental diets for 3 weeks: sucrose, sucrose-cholesterol, sucrose-cholesterol-bran or sucrose-cholesterol-guar gum. Rats fed sucrose-cholesterol-guar gum diet had significantly lower fasting plasma total cholesterol, liver triglyceride and liver cholesterol values, but higher plasma high density lipoprotein (HDL) cholesterol values than those fed sucrose-cholesterol diet. These values were similar for the sucrose-cholesterol and sucrose-cholesterol-bran groups. Fasting plasma triglyceride levels were not altered by wheat bran or guar gum. These studies indicate that while guar gum lowers fasting plasma total cholesterol and raises HDL cholesterol, wheat bran does not.     

Effects of casein and soy-protein on alpha-linolenic acid metabolism in rats.

In order to study the effects of different proteins on alpha-linolenic acid (alpha-LnA) metabolism, rats were given the diet added respectively with milk casein and soy-protein isolate (SPI) as sources of proteins and perilla oil as a source of lipid. The results obtained are as follows. The ratio of (C20:3 + C20:4)/C18:2 in liver microsomal PL, liver PE fraction, and kidney PE and PC fractions was significantly lowered by the SPI treatment when compared to the casein treatment, similarly to the already established results. In the liver microsomal PL and PE and PC fractions of liver and kidney in rats treated with SPI, there was also observed a significant decrease or a decrease tendency in the (C20:4 + C20:5)/C18:3 ratio. A similar tendency was again shown in the sigma (n-3)M/C18:3 ratio indicating metabolic conversion from C18:3(n-3) to C22:6. On the other hand, contrary to the ratios of (C20:3 + C20:4)/C18:2, sigma (n-3)M/C18:3, and (C20:3 + C20:5)/C18:3, the (C22:5 + C22:6)/C20:5 ratio which is the parameter for metabolic conversion of C20:5(n-3) was elevated in the PE and PC fraction of liver, heart and kidney in the SPI group compared to the casein group. Then, further analysis of the metabolic process from C20:5 to C22:6 showed that the C22:5/C20:5 ratio increased while the C22:6/C22:5 ratio decreased in the SPI group compared to the casein group. Based on these results, it is assumed that the metabolic process from C18:3(n-3) to C20:5(n-3) and from C22:5 to C22:6 is affected by SPI but that the elongation process from C20:5(n-3) to C22:5(n-3), on the contrary, is rather accelerated by SPI.     

Enhancement of 1,2-dimethylhydrazine-induced large bowel tumorigenesis in Balb/c mice by corn, soybean, and wheat brans

This study was designed to determine the effects of four well-characterized dietary brans on large bowel tumorigenesis induced in mice with 1,2-dimethylhydrazine (DMH). Eight-week-old barrier-derived male Balb/c mice were fed a semisynthetic diet with 20% bran added (either corn, soybean, soft winter wheat, or hard spring wheat) or a no-fiber-added control diet. Half of each group was given DMH (20 mg/kg body weight/week, subcutaneously for 10 weeks) beginning at 11 weeks of age. Surviving mice were killed 40 weeks after the first DMH injection. Tumors were not found in mice not subjected to DMH. In DMH-treated mice, tumors were found almost exclusively in the distal colon. Tumor incidences were as follows: controls, 11%; soybean group, 44%; soft winter wheat group, 48%; hard spring wheat group, 58%; and corn group, 72%. Tumors per tumor-bearing mouse ranged from 1.4 to 1.6, except in the corn group, which had 2.1. A positive correlation was found between percentage of neutral detergent fiber in the brans and tumor incidences but not between the individual components of cellulose, hemicellulose, or lignin. The enhancement of DMH-induced large bowel tumorigenesis by all four bran types may reflect a species and/or mouse strain effect that is bran-source related. These data emphasize the importance of using well-defined bran in all "fiber" studies.     

Effects of dietary fiber from wheat, corn, and soy hull bran on excretion of fecal bile acids in humans

Effects of dietary fiber on bile acid excretion and fecal bile acid concentration have been studied for seven subjects fed 26 g of either soft white wheat bran, corn bran, soybean hulls, or hard red spring wheat bran. Results indicate that even in a controlled study using a metabolic word, individual subject variation has a major impact on fecal bile acid excretion. This observation has not been fully appreciated in previous human studies. No significant change in the composition of fecal bile acids could be associated with the decrease in serum lipid levels previously reported. A method for the isolation and quantitation of fecal bile acids is described which does not require purification by thin-layer chromatography. A preliminary study of lyophilized fecal samples stored at -10 to -30 degrees C showed very little or no change in bile acid content. Samples stored at room temperatures for 11 months showed a substantial reduction in bile acid content.     

Dietary psyllium increases expression of ileal apical sodium-dependent bile acid transporter mRNA coordinately with dose-responsive changes in bile acid metabolism in rats

Psyllium (PSY), a type of dietary fiber containing mainly soluble components, has been shown to decrease serum cholesterol concentrations in several species; however, mechanisms involved are not clearly defined. Four groups of 10 rats were fed semipurified diets containing 10% dietary fiber from cellulose and/or PSY for 21 d. Increasing levels of PSY were fed (0,3.33, 6.67 and 10% PSY) with the remaining 10% made up with cellulose. Liver cholesterol, cholesterol 7alpha-hydroxylase (CYP7A) activity and mRNA, 3-hydroxy-3-methylglutaryl CoA reductase (HMGR) mRNA, ileal apical sodium-dependent bile acid transporter (ASBT) mRNA, fecal bile acids and total steroids, and intestinal bile acid content were measured. All variables responded in a dose-dependent manner to PSY in the diet. Total liver cholesterol content was significantly reduced in all groups fed PSY compared to cellulose-fed controls [138(a), 105(b), 105(b) and 93(c) micromol (SEM = 4.2) for 0, 3.33, 6.67 and 10% PSY, respectively]. Activity of CYP7A was significantly greater in all groups fed PSY compared to the cellulose-fed controls [6.36(c), 16.92(b), 15.28(b) and 20.37(a) pmol x min(-1) x mg protein(-1) (SEM = 3.19) for 0, 3.33, 6.67 and 10% PSY, respectively]. These differences in CYP7A activity were similar to differences in CYP7A, HMGR and ASBT mRNA levels. Fecal bile acid and total steroid excretion as well as total intestinal bile acids were significantly greater in rats fed PSY-containing diets compared to 0% PSY-fed rats. These results suggest that the reduction in liver cholesterol involves modulating the size and composition of the bile acid pool via regulation of ileal ASBT, CYP7A and HMGR mRNA levels.     

Effects of simultaneous dietary fish oil ingestion and sulfur amino acid supplementation on the lipid metabolism in hepatoma-bearing rats with hyperlipidemia

The effects of simultaneous dietary fish oil ingestion and sulfur amino acid (L-methionine and L-cystine) supplementation on serum lipid concentrations and various parameters related to the lipid metabolism were studied in Donryu rats subcutaneously implanted with an ascites hepatoma cell line, AH109A. A diet containing 10% fish oil was found to reduce serum triglyceride, total cholesterol, (very-low-density lipoprotein plus low-density lipoprotein)-cholesterol, phospholipid and nonesterified fatty acid (NEFA) concentrations in these animals, and dietary supplementation of 1.2% L-methionine and L-cystine also suppressed these serum lipid concentrations. Hepatic fatty acid synthesis and the availability of serum NEFA were decreased, and epididymal adipose tissue lipoprotein lipase (LPL) activity was elevated by dietary fish oil, while LPL activity in various tissues and hepatic fatty acid oxidation were increased by dietary sulfur amino acids, resulting in a reduction in the serum triglyceride concentration by dietary fish oil and sulfur amino acids, respectively. Dietary fish oil suppressed the hepatoma-induced increase in cholesterogenesis in the host liver, and dietary methionine and cystine enhanced bile acid excretion into feces, which were the causes of the hypocholesterolemic effect. In these serum lipid concentrations, there were significant effects of fish oil ingestion and sulfur amino acid supplementation, but no significant interaction between these two factors was seen. These results indicate that dietary fish oil and sulfur amino acid, L-methionine and L-cystine, have hypolipidemic effects in cancer-related hyperlipidemia, and that the effects of these two factors on the decrease in these serum lipid concentrations are additive; these two factors may affect the lipid metabolism via different pathways and mechanisms.     

Effects of ascorbic acid on blood pressure and ascorbic acid metabolism in spontaneously hypertensive rats (SH rats)

Spontaneously hypertensive rats (SH rats) were administered drinking water containing 0, 200 or 1000 ppm ascorbic acid with or without 0.5% NaCl and the usual laboratory stock diet for 130 days. The rats given ascorbic acid with or without 0.5% NaCl had a lower mean systolic blood pressure level than that of the respective control group. The difference in the mean blood pressure level from that of the control group was 18-19 mmHg for 200 ppm ascorbic acid group and 30-40 mmHg for 1000 ppm ascorbic acid group. The SH rats were shown to have some defects of ascorbic acid metabolism by lower tissue ascorbic acid levels in the liver, lung and adrenals, and by lower response of ascorbic acid synthesis to a xenobiotic than the Wistar Kyoto rats, which served as the normotensive control rats for SH rats. The abnormalities of ascorbic acid metabolism in the SH rats may be associated with, in part, their high blood pressure, because exogenous ascorbic acid prevented the blood pressure elevation of SH rats, but some other mechanism may also be involved in the effect of ascorbic acid on blood pressure.