EFFECT OF DIETARY FLAXSEED ON FATTY-ACID COMPOSITION, SUPEROXIDE, NITRIC-OXIDE GENERATION AND ANTILISTERIAL, ACTIVITY OF PERITONEAL, MACROPHAGES FROM FEMALE SPRAGUE-DAWLEY RATS

The impact of ground flaxseed (FS) or flaxseed meal (FSM) diets on the fatty acid composition and functions of rat peritoneal exudate cells (PEG) was determined. Female weanling Sprague-Dawley rats (10/group) w ere fed isocaloric AIN-76 diets supplemented with 0.0, 10.0% (w/w) FS or 6.2% (w/w) FSM. A the end of 56-days, rat serum and thiogrycollate- elicited PEC were analyzed for total lipid fatty acids. Production of nitric oxide (NO) and superoxide (O-2(-)), Listeria monocytonenes (LM) phagocytic index and antilisterial activity of resident PEC were also assessed. A significant increase in a-linolenic (C18:3), eicosapentan oic (C20:5) and docosahexanoic (C22:6) acids, as well as a significant reduction in arachidonic acid (C20:4) was observed in the serum of ra ts fed 10% FS. Dietary FS caused a significant reduction in palmitic a cid (C16:0) and an increase in stearic acid (C18:0) of PEC. Defatted F SM produced a significant increase in long chain fatty acids, which in cluded eicosadienoic acid (C20:2) in PEC and C22:6 in serum. PEC from rats fed 10.0% FS produced significantly less (about 50%) O-2(-) in re sponse to phorbol myristate acetate (PMA), than did PEC from control a nimals; dietary treatment had no effect on O-2(-) in response to LM. F SM had no impact on the O-2(-) production by PEC in response to PMA or LM. Antilisterial activity of PEC was determined by comparing bacteri al uptake after 1 hr with recovery 24 hrs later. Despite comparably eq uivalent bacterial uptake, few viable intracellular LM were recovered at T=24 for all test samples, indicating that, regardless of the dieta ry treatment, PEC were able to handle the in vitro LM infection. This bacterial clearance was accompanied by equivalent NO generation by PEC from each dietary group in response to LM. Summarily, dietary FS prod uced significant changes in fatty acid composition of serum and PEG, i nhibited O-2(-) generation by PEG, and was ineffectual to both NO prod uction by and antilisterial activity of PEC.