Protective effect of Rumenic acid rich cow's milk against colitis is associated with the activation of Nrf2 pathway in a murine model

Dietary supplementation with pure cis9, trans11 isomer of Conjugated Linoleic Acid –known as Rumenic Acid (RA)– improves cytoprotective defenses downstream through the activation of nuclear factor-E2-related factor-2(Nrf2). This capability, when Rumenic Acid is consumed in the form of foods, is still unknown. The ability of standard (St) or cow milk naturally-enriched in RA (En) to activate Nrf2 pathway and its impact on dextran sodium sulfate (DSS)-induced colitis was comparatively evaluated. Activity of Nrf2 pathway was investigated in colonic tissue of BALB/c mice, receiving 4-week supplement with skimmed milk (SK), St or St reinforced with pure RA (RSt) providing increasing RA dose (0, 124 or 404 mg RA/kg-1 b.w, respectively). Next, the anti-oxidant/ anti-inflammatory effect produced by St or En treatment (383 mg RA/kg-1 b.w.) was explored. Finally, macroscopic and histomorphologic features of colitis were evaluated in animals challenged with 5% (w/v) DSS, at the end of St or En treatment. Significant activation of Nrf2 pathway is associated with RSt and En intake (P