Modulatory effect of a-linolenic acid-rich garden cress (Lepidium sativum L.) seed oil on inflammatory mediators in adult albino rats

Vegetable oils containing a-linolenic acid (ALA; 18 : 3n-3) have been shown to modulate the functions of immunocompetent cells. The aim of the present study was to understand the modulatory effect of ALA-rich garden cress (Lepidium sativum L.) seed oil (GCO) on lipid composition, spleen lymphocyte (SL) proliferation and inflammatory mediator production by peritoneal macrophages (PMF) in rats. Female Wistar rats were fed diets containing either GCO (2·5, 5·0 and 10 %, w/w) or sunflower oil (SFO, 10 % w/w) for 8 weeks. Ex vivo proliferation of SL was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. IL-2 and TNF-a in SL and PMF were analysed by ELISA. Inflammatory mediators such as NO, leukotriene B4 (LTB4) and H2O2 were measured in mitogen-activated PMF. GCO significantly increased the levels of ALA, EPA and DHA, but reduced linoleic acid and arachidonic acid in SL and PMF lipids. GCO (10 %) significantly decreased the concanavalin A (Con-A)and phytohaemagglutinin-mediated proliferation of SL by 54 and 38 %, respectively, in comparison with SFO. A marginal decrease in IL-2 and TNF-a was observed in Con-A-stimulated SL and lipopolysaccharide-stimulated PMF. LTB4 levels in Ca ionophore-stimulated PMF were reduced by 40 % in GCO-fed rats. NO release in response to various stimuli was significantly decreased in PMF of GCO-fed rats. The present study is the first report on the modulatory efficacy of GCO on immunomediators in rats. GCO modulated inflammatory mediators such as NO and LTB4, and thus may play a role in alleviating inflammatory conditions favourably.