Roles of nuclear receptors in the up-regulation of hepatic cholesterol 7α-hydroxylase by cholestyramine in rats

Shibata, Shinya; Hayakawa, Kazuhito; Egashira, Yukari; Sanada, Hiroo

doi:10.1016/j.lfs.2006.10.003

Cited by 24 publications

(23 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…26) In a previous study, cholestyramine increased the hepatic activities of HMGR and CYP7A1 in rats fed H-based diets, and increased only the activity of CYP7A1 in rats fed C-based diets. 7) Although we did not determine the intestinal pool size or fecal excretion of steroids in the present study, our previous study indicate that CP and its indigestible fraction increased the total amount of fecal steroids in cholesterol-fed rats.…”

Section: Discussionmentioning

confidence: 58%

“…The PCR primers used in the present study were described previously. 7) PCR plates (96 wells) were heated for 2 min at 50 C and for 10 min at 95…”

Section: Preparation Of Liver Microsomes (Experiments 1)mentioning

confidence: 99%

“…Cholestyramine, a resin that strongly binds bile acids, is used as a hypocholesterolemic drug and remarkably enhances CYP7A1 activity. 3,7) Overexpression of CYP 7A1 reduced the plasma LDL cholesterol concentration in mice lacking the LDL receptor gene. 8) Thus, upregulating the expression of CYP7A1 is thought to be one way of effectively lowering the serum cholesterol level.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Hypocholesterolemic Mechanism ofChlorella:Chlorellaand Its Indigestible Fraction Enhance Hepatic Cholesterol Catabolism through Up-Regulation of Cholesterol 7α-Hydroxylase in Rats

Shibata

Hayakawa

Egashira

et al. 2007

Bioscience, Biotechnology, and Biochemistry

Self Cite

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 58%

“…The PCR primers used in the present study were described previously. 7) PCR plates (96 wells) were heated for 2 min at 50 C and for 10 min at 95…”

Section: Preparation Of Liver Microsomes (Experiments 1)mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Hypocholesterolemic Mechanism ofChlorella:Chlorellaand Its Indigestible Fraction Enhance Hepatic Cholesterol Catabolism through Up-Regulation of Cholesterol 7α-Hydroxylase in Rats

Shibata

Hayakawa

Egashira

et al. 2007

Bioscience, Biotechnology, and Biochemistry

Self Cite

View full text Add to dashboard Cite

“…Gupta et al reported that feeding of cholestyramine in rats resulted in a marked repression of hepatic SHP mRNA expression (22). In contrast, Shibata et al did not observe a reduction of hepatic SHP mRNA in the feeding of cholestyramine in rats, although CYP7A1 expression was enhanced (23). Since no information is available on effects of bile acid sequestrants on the expression of hepatic ABCG5 and ABCG8, more studies will be necessary on this point.…”

Section: Discussionmentioning

confidence: 99%

Dietary Soy Protein Isolate and Its Undigested High Molecular Fraction Upregulate Hepatic ATP-Binding Cassette Transporter G5 and ATP-Binding Cassette Transporter G8 mRNA and Increase Biliary Secretion of Cholesterol in Rats

Ikeda¹,

Kudo²,

Hamada³

et al. 2009

J Nutr Sci Vitaminol

View full text Add to dashboard Cite

Summary Dietary soy protein isolate (SPI) and its undigested high molecular fraction (HMF) exhaustively digested with proteases, compared with casein (CAS), significantly reduced serum and liver cholesterol concentration in rats. Biliary excretion of cholesterol was significantly higher in rats fed SPI and HMF than in those fed CAS. Hepatic expression of ATP-binding cassette transporter G5 (ABCG5) and ATP-binding cassette transporter G8 (ABCG8) mRNA was significantly higher in rats fed SPI and HMF than in those fed CAS. These observations suggest that increased biliary excretion of cholesterol in SPI and HMF groups is caused by the enhanced expression of Abcg5/Abcg8. Key Words ATP-binding cassette transporter G5, ATP-binding cassette transporter G8, bile, cholesterol, soy protein isolate ATP-binding cassette transporter G5 (ABCG5) and ATP-binding cassette transporter G8 (ABCG8) are mainly expressed in the liver and the intestine ( 1 ). It has been suggested that ABCG5 and ABCG8 have a function to excrete sterols from intestinal cells to the intestinal lumen and from the liver to the bile ( 1 ). Although functions of ABCG5 and ABCG8 on sterol excretion gradually become apparent, the contribution of ABCG5 and ABCG8 to cholesterol metabolism in the whole body is not fully understood and scarcely any information on regulation of ABCG5 and ABCG8 expression by dietary components has been obtained.It has been reported that dietary soy protein isolate (SPI) and its undigested high molecular fraction (HMF) lower serum cholesterol concentration in experimental animals ( 2 -4 ). One of the mechanisms of hypocholesterolemic effects of SPI and HMF is an increase in fecal bile acid excretion ( 3 , 4 ). The increased excretion of bile acids can be caused by their binding with SPI and HMF ( 3 , 4 ). Fecal excretion of neutral steroids originated from cholesterol was also increased by the feeding of SPI and HMF in rats fed a high-cholesterol diet ( 3 -5 ). It has been thought that increased excretion of cholesterol and the metabolite coprostanol is caused by reduced availability of bile acids for the bile salt micelle in the intestinal lumen and therefore by reduced solubility of cholesterol in the micelle ( 3 , 4 , 6 ). Although increased fecal excretion of cholesterol and coprostanol can be caused by increased expressions of ABCG5 and ABCG8 in the liver and the intestine, no information is available about whether SPI and HMF influence expressions and functions of ABCG5 and ABCG8 in the liver and the intestine. In the present study, we examined effects of SPI and HMF on cholesterol metabolism in relation to mRNA expressions of ABCG5 and ABCG8 in the liver and the intestine of rats.

show abstract

“…Some Chlorella species are widely used as a dietary supplement in many countries, especially in East Asia (e.g., Japan, Taiwan, Korea). Chlorella regularis has been reported to potentially prevent lifestylerelated diseases (Shibata et al, 2003;Shibata and Sansawa, 2006;Shibata et al, 2007). Chlorella powder (CP) made from C. regularis contains large amounts of carotenoids such as lutein, α-carotene, and β-carotene (approx.…”

Section: Introductionmentioning

confidence: 99%

Bioavailability of Lutein in Chlorella Powder: A Single Ingestion of Chlorella Powder Raises Serum Lutein Concentrations in Healthy Human Volunteers

Shibata

Hayakawa

2009

FSTR

Self Cite

View full text Add to dashboard Cite

Chlorella powder (CP), a dietary supplement made from a green alga, contains abundant lutein (2.8 mg/g), but the bioavailability of lutein in CP has not been evaluated. In the present study, we assessed the effect of a single ingestion of CP (3 or 6 g) in tablet form on serum lutein concentrations in humans (n = 21). At 1 d, serum lutein concentrations increased from baseline values by 34% (25.6 nM/mg-lutein intake) after 3 g CP and by 66% (21.4 nM/mg-lutein intake) after 6 g CP. These results suggest that lutein in CP is highly bioavailable.Keywords: bioavailability, Chlorella, green alga, lutein *To whom correspondence should be addressed. E-mail: shinya-shibata@yakult.co.jp IntroductionLutein is the most abundant carotenoid in nature, and green leafy vegetables are the most popular source of dietary lutein. Lutein and zeaxanthin exist in the lens of the eye and the macular region of the retina (Krinsky et al., 2003). Many studies have indicated that the consumption of lutein-and zeaxanthin-rich food is associated with a reduced risk of agerelated macular degeneration (AMD) and cataracts (Moeller et al., 2000;Seddon et al., 1994). Seddon et al. (1994) have reported that daily intake of 6 mg of lutein was associated with a reduced risk of AMD. Richer et al. (2004) reported that a daily intake of 10 mg of lutein improved the vision of AMD patients.During the absorption of carotenoids from food, the carotenoids are initially transferred from the intact food matrix into emulsified lipid droplets. Subsequently, they are mixed into micelles, as are other dietary lipids, and then absorbed by the small intestine. These processes are influenced by various characteristics of the food; for example, fat facilitates the absorption of carotenoids, whereas dietary fiber inhibits it (van het Hof et al., 2000). Thus, to consume adequate amounts of vegetables and fruits in order to ensure sufficient intake of carotenoids, we must determine the bioavailability of carotenoids in food, not just the carotenoid content of the food.Chlorella species are unicellular green algae with high photosynthetic efficiency, and are rich in protein, essential nutrients, and plant pigments. Some Chlorella species are widely used as a dietary supplement in many countries, especially in East Asia (e.g., Japan, Taiwan, Korea). Chlorella regularis has been reported to potentially prevent lifestylerelated diseases (Shibata et al., 2003;Shibata and Sansawa, 2006;Shibata et al., 2007). Chlorella powder (CP) made from C. regularis contains large amounts of carotenoids such as lutein, α-carotene, and β-carotene (approx. 2.5 mg/g, 250 μg/g, and 500 μg/g, respectively). Thus, the ingestion of CP could improve low dietary intake of lutein due to low consumption of vegetables and fruits, because only a few grams of CP can supply 6 to 10 mg of lutein. However, to our knowledge, there is no available information about carotenoid bioavailability of CP.The aim of the present study was to determine the bioavailability of lutein from CP in humans. We assessed the e...

show abstract

Roles of nuclear receptors in the up-regulation of hepatic cholesterol 7α-hydroxylase by cholestyramine in rats

Cited by 24 publications

References 27 publications

Hypocholesterolemic Mechanism ofChlorella:Chlorellaand Its Indigestible Fraction Enhance Hepatic Cholesterol Catabolism through Up-Regulation of Cholesterol 7α-Hydroxylase in Rats

Hypocholesterolemic Mechanism ofChlorella:Chlorellaand Its Indigestible Fraction Enhance Hepatic Cholesterol Catabolism through Up-Regulation of Cholesterol 7α-Hydroxylase in Rats

Dietary Soy Protein Isolate and Its Undigested High Molecular Fraction Upregulate Hepatic ATP-Binding Cassette Transporter G5 and ATP-Binding Cassette Transporter G8 mRNA and Increase Biliary Secretion of Cholesterol in Rats

Bioavailability of Lutein in Chlorella Powder: A Single Ingestion of Chlorella Powder Raises Serum Lutein Concentrations in Healthy Human Volunteers

Contact Info

Product

Resources

About