The aim of the study was to investigate the impact of a moderate zinc deficiency and a high intake of polyunsaturated fat on the mRNA expression of peroxisome-proliferator-activated receptor alpha (PPARα), peroxisome-proliferator-activated receptor gamma (PPARγ), and mitochondrial Δ3Δ2-enoyl-CoA isomerase (ECI) in the liver. Weanling rats were assigned to five groups (eight animals each) and fed semi-synthetic, low-carbohydrate diets containing 7 or 50 mg Zn/kg (low-Zn (LZ) or high-Zn (HZ)) and 22% cocoa butter (CB) or 22% safflower (SF) oil for four weeks. One group each was fed the LZ-CB, LZ-SF, or HZ-SF diet free choice, and one group each was fed the HZ-CB and HZ-SF diets in restricted amounts according to intake of the respective LZ diets. The LZ diets markedly lowered growth and zinc concentrations in plasma and femur. Hepatic mRNA levels of PPARα, PPARγ, and ECI were not reduced by the moderate zinc deficiency. Overall, ECI-mRNA abundance was marginally higher in the SF-fed than in the CB-fed animals.

Auxiliary enzymes participate in β-oxidation of unsaturated fatty acids. The objective of the study was to investigate the impact of a moderate zinc deficiency and a high intake of polyunsaturated fat on Δ(3)Δ(2)-enoyl-CoA isomerase (ECI) in the liver and other tissues. Five groups of eight weanling rats each were fed moderately zinc-deficient (ZD) or zinc-adequate (ZA) semisynthetic diets (7 or 50 mg Zn/kg) enriched with 22 % cocoa butter (CB) or 22 % safflower oil (SO) for 4 weeks: (1) ZD-CB, fed free choice; (2) ZA-CBR, ZA-CB diet fed in equivalent amounts consumed by the ZD-CB group; (3) ZD-SO, fed free choice; (4) ZA-SOR, ZA-SO diet fed in equivalent amounts consumed by the ZD-SO group; and (5) ZA-SO, fed free choice. Growth and Zn status markers were markedly reduced in the ZD groups. ECI activity in the liver of the animals fed the ZD- and ZA-SO diets were significantly higher (approximately 2- and 3-fold, respectively) as compared with the CB-fed animals, whereas activities in extrahepatic tissues (kidneys, heart, skeletal muscle, testes, adipose tissue) were not altered by dietary treatments. Transcript levels of the mitochondrial Eci gene in the liver did not significantly differ between ZD and ZA rats, but were 1.6-fold higher in the ZA-SO- than in the ZD-CB-fed animals (P < 0.05). It is concluded that diets enriched with safflower oil as a source high in linoleic acid induce markedly increased hepatic ECI activities and that a moderate Zn deficiency does not affect transcription of the mitochondrial Eci gene in the liver.