| The aim of this intervention study was to investigate effects of plant oil and hypoxia on lipid metabolism (in liver and serum) and antioxidant status (in liver) of rats.80male Sprague-Dawley (SD) rats were randomly assigned to four groups, with different dietary intervention:basal diet (control), soybean oil, rapeseed oil and flaxseed oil (total fat was replaced by plant oil, respectively). Four weeks later, every group was equally divided into2subgroups, one was put into hypobaric chamber to simulate altitude hypoxia of3000m for another4weeks, and the other was at normal atmospheric pressure.The body weight gained were significantly reduced in flaxseed oil and hypoxia rapeseed oil groups during first and second4weeks respectively, had a parallel change with food intakes. The arranging of myocardial cell and heart index were significantly influenced in hypoxia animals by HE stain. The fatty acid profile, especially n-3PUFA in liver was highly consistent with it in diet.Triglyceride (TG) and low density lipoprotein (LDL) contents were reduced and high density lipoprotein (HDL) was enhanced both in liver and serum, while total cholesterol (TC) was reduced significantly in flaxseed oil group. Plant oil and hypoxia had no effect on serum glucose (GLU) content, while pyruvic acid (PA) was increased in soybean oil group. Serum total protein (TP) and albumin (ALB)(only in normal group) contents were increased markedly, while blood urea nitrogen (BUN) was not influenced by plant oil. As a contrast, hypoxia had no significant effects on lipid, glucose, and protein metabolism.Another animal trial was carried out in order to investigate the influence of different hypoxia duration on mechanism of lipid-lower effect. Forty male rats were divided into2groups, one group had13animals fed basal diet (control), and the other had21animals fed flaxseed oil diet. Four weeks later,6animals were chosen in each group and put at normal atmospheric pressure; the others were put into hypobaric chamber to simulate altitude hypoxia of3000m. Hypoxia duration were1day,1week, and4weeks. Control-hypoxia, control-normal and flaxseed oil-normal were fed for another4weeks. All the animals were sacrificed and fatty acid synthase (FAS), hormone sensitive lipase (HSL), lipoprotein lipase (LPL) were detected. Results showed that flaxseed oil had no effect on liver FAS, can increase HSL and decrease LPL activity notably (hypoxia group). Additionally, different hypoxia duration also had no influence on FAS. However, hypoxia for1week led to a marked rise in HSL activity, but fall to the same level of normal group when hypoxia lasted for4weeks. Interestingly, the change of liver LPL was opposite to HSL, hypoxia for1day and1week induced a marked fall, which returned to normal group level after4weeks’ hypoxia.Liver malonaldehyde (MDA) was reduced, and glutathione peroxidase (GSH-Px) was increased in flaxseed oil group. However, hypoxia had no significant effects on both lipid metabolism and antioxidation. Uncoupling protein (UCP) expression on protein and mRNA levels was tested in liver of rats. The results showed that flaxseed oil and4weeks’hypoxia didn’t influence UCP2mRNA. Considered UCP2protein level, flaxseed oil exhibited a notably increase (normal group) and hypoxia showed a significant fall (control group). Moreover, hypoxia for1day and1week can decrease UCP2protein, and hypoxia for4weeks led to an increase to the same level in normal group. Similarly, UCP2mRNA had an obvious decrease after1week’s hypoxia, and then increased to normal group level, too. |
