No abstract

We evaluated the effects of partly substituting lard with marine n-3 fatty acids (FA) on body composition and weight, adipose tissue distribution and gene expression in five adipose depots of male Wistar rats fed a high-fat diet. Rats were fed diets including lard (19·5 % lard) or n-3 FA (9·1 % lard and 10·4 % Triomare) for 7 weeks. Feed consumption and weight gain were similar, whereas plasma lipid concentrations were lower in the n-3 FA group. Magnetic resonance imaging revealed smaller visceral (mesenteric, perirenal and epididymal) adipose depots in the n-3 FA-fed animals (35, 44 and 32 % reductions, respectively). n-3 FA feeding increased mRNA expression of cytokines as well as chemokines in several adipose depots. Expression of Adipoq and Pparg was enhanced in the mesenteric adipose depots of the n-3 FA-fed rats, and fasting plasma insulin levels were lowered. Expression of the lipogenic enzymes Acaca and Fasn was increased in the visceral adipose depots, whereas Dgat1 was reduced in the perirenal and epididymal depots. Cpt2 mRNA expression was almost doubled in the mesenteric depot and liver. Carcass analyses showed similar body fat (%) in the two feeding groups, indicating that n-3 FA feeding led to redistribution of fat away from the visceral compartment.

Tamoxifen can induce hepatic steatosis in women. In this study, we wanted to elucidate the mechanism behind the tamoxifen-induced accumulation of triacylglycerol in liver in female rats, and we hoped to prevent this development by combination treatment with the modified fatty acid tetradecylthioacetic acid (TTA). The increased hepatic triacylglycerol level after tamoxifen treatment was accompanied by decreased acetyl-coenzyme A carboxylase (ACC) and FAS activities, increased glycerol-3-phosphate acyltransferase (GPAT) activity, and a tendency to increased diacylglycerol acyltransferase (DGAT) activity. The activities and mRNA levels of enzymes involved in b-oxidation, ketogenesis, and uptake of lipids from liver were unaffected by tamoxifen, whereas the uptake of lipoproteins was unchanged and the uptake of fatty acids was decreased. Combination treatment with tamoxifen and TTA (Tam1TTA) normalized the hepatic triacylglycerol level and increased the activities of ACC, FAS, GPAT, and DGAT compared with tamoxifentreated rats. The activities and mRNA levels of enzymes involved in b-oxidation, ketogenesis, and uptake of lipids were increased after Tam1TTA treatment. In conclusion, tamoxifen increased the hepatic triacylglycerol level, probably as a result of increased triacylglycerol biosynthesis combined with unchanged b-oxidation. The tamoxifen-induced accumulation of triacylglycerol was prevented by cotreatment with TTA, through mechanisms of increased mitochondrial and peroxisomal b-oxidation. The anti-estrogen agent tamoxifen has been used as an effective treatment for estrogen receptor-positive breast cancers for several years (1). However, tamoxifen treatment is associated with an increased risk of developing fatty liver (steatosis) (2-4), and it is reported that as many as 43% of women with breast cancer treated with tamoxifen may develop steatosis within the first 2 years of treatment (4). It has been hypothesized that impaired fatty acid b-oxidation could be the cause of fatty liver after tamoxifen treatment (5, 6).The modified fatty acid tetradecylthioacetic acid (TTA) is a ligand for all peroxisome proliferator-activated receptors (PPARs) (7) and has shown promise in the prevention and treatment of common lipid disorders and insulin resistance (8). TTA increases both mitochondrial and peroxisomal b-oxidation in liver (9) and therefore may be a valuable tool for the treatment of fatty liver.In this study, female rats with 7,12-dimethylbenz[a]anthracene-induced mammary tumors were treated with tamoxifen, TTA, or a combination of tamoxifen and TTA (Tam1TTA) for 14 days after palpable tumors developed. We had two aims in this study: first, we wanted to elucidate the mechanism behind the accumulation of triacylglycerol in liver after tamoxifen treatment in this rat model; second, we wanted to investigate whether cotreatment with TTA could abolish this undesirable side effect of tamoxifen. To clarify the mechanisms involved, we measured the activities and gene expression of enzymes controlling the hep...