Eicosanoid Production and Cytokine mRNA Levels in Piglets Fed with Various Edible Oils

Abstract

To investigate the interactions between cytokine gene expressions and eicosanoid synthesis, 16 piglets were randomized into four groups and fed diets containing 3.6% coconut oil, fish oil, lard, or soybean oil plus 0.4% soybean oil for 21 days to modulate the synthesis of eicosanoids including leukotriene (LT), prostacyclin (PG), and thromboxane (TX) in the lungs. Interleukin-4 (IL-4), interleukin-8 (IL-8), and interferony-γ (IFN-γ) gene expressions in spleen and thymus were examined using RT-PCR. The results showed that fish oil effectively inhibited the synthesis of PG and TX (P＜0.05) in lungs but did not reduce the synthesis of pulmonary LT. Interleukin-4, IL-8, and IFN-γ gene expressions in the spleen and thymus were not affected by dietary fat. However, a significant positive correlation was observed between LT synthesis in the lung and IL-4 gene expression in the spleen (r=0.80, P=0.0006). Stimulated-LT production in lungs tended to be positively correlated to splenic IL-8 gene expression (r=0.60, P=0.057). Negative correlation was found between IL-4 and IFN-γ gene expressions in the spleen. The mRNA levels of IFN-γ were also negatively correlated to those of IL-8 in the spleen. Therefore, the positive correlation between splenic IL-4 gene expression and the release of LT in the lungs was consistent with clinical features in asthmatic patients. In contrast, the negative correlation between IL-4 and IFN-γ gene expressions in spleen idicated that IFN-γ and IL-4 gene expressions in the spleen were apparently converse.