title: Dietary gamma-linolenic acid in the form of borage oil causes less body fat accumulation accompanying an increase in uncoupling protein 1 mRNA level in brown adipose tissue.
abstract: Rats were fed a low-fat diet containing 2% safflower oil or 20% fat diets containing either safflower oil rich in linoleic acid, borage oil containing 25% gamma (gamma)-linolenic acid or enzymatically prepared gamma-linolenic acid enriched borage oil containing 47% gamma-linolenic acid for 14 days. Energy intake and growth of animals were the same among groups. A high safflower oil diet compared with a low-fat diet caused significant increases in both epididymal and perirenal white adipose tissue weights. However, high-fat diets rich in gamma-linolenic acid failed to do so. Compared with a low-fat diet, all the high-fat diets increased mRNA levels of uncoupling protein 1 and lipoprotein lipase in brown adipose tissue. The extents of the increase were greater with high-fat diets rich in gamma-linolenic acid. Various high-fat diets, compared with a low-fat diet, decreased glucose transporter 4 mRNA in white adipose tissue to the same levels. The amount and types of dietary fat did not affect the leptin mRNA level in epididymal white adipose tissue. However, a high safflower oil diet, but not high-fat diets rich in gamma-linolenic acid relative to a low-fat diet, increased perirenal white adipose tissue leptin mRNA levels. All high-fat diets, relative to a low-fat diet, increased the hepatic mitochondrial fatty acid oxidation rate and fatty acid oxidation enzyme mRNA abundances to the same levels. High-fat diets also increased these parameters in the peroxisomal pathway, and the increases were greater with high-fat diets rich in gamma-linolenic acid. The physiological activity in increasing brown adipose tissue gene expression and peroxisomal fatty acid oxidation was similar between the two types of borage oil differing in gamma-linolenic acid content. It was suggested that dietary gamma-linolenic acid attenuates body fat accumulation through the increase in gene expressions of uncoupling protein 1 in brown adipose tissue. An increase in hepatic peroxisomal fatty acid oxidation may also contribute to the physiological activity of gamma-linolenic acid in decreasing body fat mass.
authors.affiliation: Laboratory of Nutrition Biochemistry, National Food Research Institute, Ministry of Agriculture, Forestry and Fisheries, Tsukuba Science City, Ibaraki, Japan. youkot@nfri.affrc.go.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Takahashi
authors.forename: T
authors.initials: T
authors.lastname: Ide
authors.forename: H
authors.initials: H
authors.lastname: Fujita
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D002001:Adipose Tissue, Brown / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis*; D004032:Diet; D018752:Diet, Fat-Restricted; D005227:Fatty Acids / Q000378:metabolism; D007473:Ion Channels; D020738:Leptin / Q000378:metabolism; D008071:Lipoprotein Lipase / Q000378:metabolism; D008099:Liver / Q000201:enzymology; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis*; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010171:Palmitoyl Coenzyme A / Q000378:metabolism; D020675:Peroxisomes / Q000378:metabolism; D010938:Plant Oils / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D012450:Safflower Oil / Q000494:pharmacology; D000071256:Uncoupling Protein 1; D017965:gamma-Linolenic Acid / Q000494:pharmacology*
chemical_list: D002352:Carrier Proteins; D005227:Fatty Acids; D007473:Ion Channels; D020738:Leptin; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D009004:Monosaccharide Transport Proteins; D010938:Plant Oils; D012333:RNA, Messenger; C000604373:Ucp1 protein, rat; D000071256:Uncoupling Protein 1; D010171:Palmitoyl Coenzyme A; D017965:gamma-Linolenic Acid; D012450:Safflower Oil; D008071:Lipoprotein Lipase; C079363:borage oil; D010100:Oxygen