title: Dietary single cell protein reduces fatty liver in obese Zucker rats.
abstract: There is growing evidence that dietary proteins may interfere with lipid metabolism. We therefore examined the effects of feeding obese Zucker rats a single cell protein (SCP) with low ratios of methionine:glycine and lysine:arginine for 6 weeks. SCP feeding reduced the hepatic steatosis and lowered the plasma transaminase levels when compared with casein-fed rats (controls). The fatty acid oxidation was increased in liver mitochondria and peroxisomes, whereas the activities of enzymes involved in lipogenesis and TAG biosynthesis were unaffected. SCP feeding affected the fatty acid composition of liver lipids and plasma, and reduced the mRNA levels of the fatty acid desaturases. The decreased gene expression of stearoyl-CoA desaturase suggested that the fatty acids were directed towards oxidation rather than esterification as TAG. The decreased mRNA levels of VLDL-receptor and lipoprotein lipase in the liver after SCP feeding suggested that the uptake of TAG-rich lipoprotein to the liver was decreased. To conclude, the reduced fatty liver by SCP feeding may be caused by the increased capacity for fatty acid beta-oxidation in the liver, combined with changed fatty acid composition and possibly a reduced hepatic clearance of circulating VLDL. An increased awareness of the effect of dietary proteins on lipid metabolism could be of relevance in future dietary treatment of non-alcoholic fatty liver disease.
authors.affiliation: Section of Medical Biochemistry, Institute of Medicine, Haukeland University Hospital, University of Bergen, N-5021 Bergen, Norway. nkjgu@uib.no
authors.forename: Oddrun Anita
authors.initials: OA
authors.lastname: Gudbrandsen
authors.forename: Hege
authors.initials: H
authors.lastname: Wergedahl
authors.forename: Bjørn
authors.initials: B
authors.lastname: Liaset
authors.forename: Marit
authors.initials: M
authors.lastname: Espe
authors.forename: Sverre
authors.initials: S
authors.lastname: Mørk
authors.forename: Rolf Kristian
authors.initials: RK
authors.lastname: Berge
mesh_terms: D000818:Animals; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage*; D005234:Fatty Liver / Q000378:metabolism / Q000628:therapy*; D008071:Lipoprotein Lipase / Q000378:metabolism; D008074:Lipoproteins / Q000737:chemistry / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D009765:Obesity / Q000378:metabolism / Q000628:therapy*; D051381:Rats; D011924:Rats, Zucker; D011973:Receptors, LDL / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013230:Stearoyl-CoA Desaturase / Q000378:metabolism; D000637:Transaminases / Q000032:analysis / Q000378:metabolism; D014280:Triglycerides / Q000032:analysis / Q000097:blood / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D004044:Dietary Proteins; D008074:Lipoproteins; D011973:Receptors, LDL; D014280:Triglycerides; D014409:Tumor Necrosis Factor-alpha; C036053:VLDL receptor; C012551:single cell proteins; D013230:Stearoyl-CoA Desaturase; D000637:Transaminases; D008071:Lipoprotein Lipase