Hypocholesterolemic effect of Nostoc commune var. sphaeroides Kützing, an edible blue-green alga.
BACKGROUND
Intake of an edible blue-green alga Nostoc commune var. sphaeroides Kützing (N. Commune) has been shown to lower plasma total cholesterol concentration, but the mechanisms behind the hypocholesterolemic effect have not been elucidated.


OBJECTIVE
To elucidate the mechanisms underlying the cholesterol-lowering effect of N. commune in mice.


METHODS
Male C57BL/6J mice were fed the AIN-93 M diet supplemented with 0 or 5% (wt/wt) dried N. Commune for 4 weeks. Lipid levels in the plasma and liver, intestinal cholesterol absorption and fecal sterol excretion were measured. Expression of hepatic and intestinal genes involved in cholesterol metabolism was evaluated by quantitative realtime PCR.


RESULTS
N. commune supplementation significantly reduced total plasma cholesterol and triglyceride concentrations by approximately 20% compared to controls. Intestinal cholesterol absorption was significantly decreased, while fecal neutral sterol output was significantly increased in N. commune-fed mice. mRNA levels of the cholesterol transporters such as Niemann Pick C1 Like 1, scavenger receptor class B type 1, ATP-binding cassette transporters G5 and A1 in small intestine were not significantly different between two groups. Hepatic lipid contents including total cholesterol, triglyceride and free cholesterol in N. commune-fed mice were not significantly altered. However, the expression of cholesterol modulating genes including sterol regulatory element binding protein-2 and 3-hydroxy-3-methylglutaryl coenzyme A reductase were significantly increased in mice fed N. commune.


CONCLUSIONS
N. commune supplementation exerted a hypocholesterolemic effect in mice, largely in part, by reducing intestinal cholesterol absorption and promoting fecal neutral sterol excretion.
Rasmussen
Heather E
HE
Department of Nutrition and Health Sciences, University of Nebraska, Lincoln, NE 68583-0806, USA.
Blobaum
Kara R
KR
Jesch
Elliot D
ED
Ku
Chai Siah
CS
Park
Young-Ki
YK
Lu
Fan
F
Carr
Timothy P
TP
Lee
Ji-Young
JY
D000818:Animals; D000924:Anticholesteremic Agents / Q000008:administration & dosage*; D002784:Cholesterol / Q000097:blood / Q000378:metabolism; D019587:Dietary Supplements; D064429:Fatty Acid Synthases / Q000235:genetics / Q000378:metabolism; D005243:Feces / Q000737:chemistry; D005612:Freeze Drying; D005786:Gene Expression Regulation; D006903:Hydroxymethylglutaryl CoA Reductases / Q000235:genetics / Q000378:metabolism; D007408:Intestinal Absorption; D008055:Lipids / Q000032:analysis / Q000097:blood; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008297:Male; D008516:Medicine, Chinese Traditional; D051379:Mice; D008810:Mice, Inbred C57BL; D050501:Nostoc commune; D009929:Organ Size; D011973:Receptors, LDL / Q000235:genetics / Q000378:metabolism; D013256:Steroids / Q000032:analysis; D051782:Sterol Regulatory Element Binding Protein 2 / Q000235:genetics / Q000378:metabolism
D000924:Anticholesteremic Agents; D008055:Lipids; D011973:Receptors, LDL; D013256:Steroids; D051782:Sterol Regulatory Element Binding Protein 2; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases; D064429:Fatty Acid Synthases