Effects of polyunsaturated fatty acids on the proliferation of mitogen stimulated bovine peripheral blood mononuclear cells.

The present study aimed at analysis of the effects of polyunsaturated fatty acid (PUFA), linoleic acid (LA, C18:2n - 6) and linolenic acid (LNA, C18:3n - 3) on bovine peripheral blood mononuclear cells (PBMC) in vitro. Both mitogen (ConA)-induced proliferative lymphocyte responsiveness during 4 days of culture and eicosanoid (prostaglandin E(2) (PGE(2)) and leukotriene B(4) (LTB(4))) production during 36 h were determined in relation to the absence or presence of various concentrations of LA and LNA (0, 1, 5, 25, 125 and 250 microM). Mitogen-driven proliferative responses of lymphocytes tended to be uninfluenced in the presence of lower concentrations of LA, whereas significant inhibition was observed at the higher concentrations of LA (125 and 250 microM). However, increasing amounts of LNA did not affect the proliferation. ConA stimulation induced a clear PGE(2) response, which significantly decreased in the presence of 250 microM of LA. In addition, increasing amounts of LNA, but not LA, led to a significant decrease in LTB(4) levels. However, The production of LTB(4) did not alter due to mitogenic stimulation. In conclusion, the present study shows that bovine mononuclear cells may functionally be influenced by the presence of PUFA in their environment. Further studies need to be conducted to clarify in vivo consequences of these findings in a situation of PUFA enriched rations in ruminants.

Effects of a single dose of dexamethasone-21-isonicotinate on the metabolism of heifers in early lactation.

Eight Swedish crossbred heifers, about two-and-a-half years old, were given a single intramuscular dose of dexamethasone-21-isonicotinate between nine and 15 days after they had calved and eight similar heifers were left untreated. The treatment had no significant effects on the lipolytic activity of the heifers' fat tissues, and no effect on the concentrations of non-esterified fatty acids and beta-hydroxybutyrate in blood or the triacylglycerol content of the liver. However, there were significant increases in plasma glucose concentrations two days after the injection and in plasma insulin concentrations two and four days after the injection.

Effect of a dietary n-6 polyunsaturated fatty acid supplement on distinct immune functions of goats.

The aim of this study was to investigate whether dietary n-6 polyunsaturated fatty acids (PUFA) alter immune functions as lymphocyte blastogenesis, expression of lymphocyte and monocyte markers, and cell adhesion molecules of the integrin family in goats. Dutch White castrated male goats received a diet either rich in olive oil (control group, n = 4) or rich in corn oil (test group, n = 4) over a period of 3 weeks. The animals in the test group had significantly higher linoleic acid (LA, 18:2n-6) levels in plasma on days 7, 14 and 21 of the diet than control animals. This was also true for washed erythrocyte membranes at day 21. A significant reduction in the percentage of alpha-4 integrin (CD49d) expressing lymphocytes was observed in goats fed LA rich corn oil at day 21. However, no changes were observed in either lymphocyte proliferative responses to ConA and PHA or the expression of other lymphocyte/monocyte markers. In conclusion, feeding corn oil rich in LA caused significant increases in the proportion of LA in the fatty acid composition of plasma and erythrocyte membranes and was accompanied by a significant decrease of the adhesion molecule alpha-4 integrin (CD49d) on lymphocytes but not on monocytes.