Cardiovascular benefits of dietary corn fractions in low density lipoprotein receptor knockout mice

Atherosclerotic cardiovascular disease (CVD) is a major source of morbidityand mortality. Accumulating evidence has suggested that in-take of whole grains may play a role in prevention of CVD. The exactmechanisms, however, are still not clearly understood. In this study,CVD benefits of corn fractions (aleurone, endosperm and germ) havebeen investigated through a number biomarkers including the activityof antioxidant enzymes (superoxide dismutase (SOD), glutathioneperoxidase (GPx) and catalase (CAT)), oxidative stress indicator(1,1-diphenyl-2-picrylhydrazyl-scavenging (DPPH)) in plasma and liversamples as well as lipoprotein profile, and morphological and morphometricalanalysis of atherosclerotic lesions in aortic root in lowdensity lipoprotein receptor knockout (LDL-r-KO) mice. Four groups ofmale LDL-r-KO mice (n=32; 8 mice/group) were fed with the experimentaldiets supplemented with (3 treated groups) or without (1 controlgroup) 5% (w/w) of each of hand-separated corn fraction for 10weeks. All diets were supplemented with 0.06% (w/w) dietary cholesterol.LDL-r-KO mice are well known models for studying LDL oxidationand atherosclerosis. This study was approved by the Animal CareCommittee at the University of Manitoba. Blood samples, hearts, liver,and feces were collected and used for biochemical and histologicalexamination. Consumption of aleurone and germ fractions significantlyreduced the size and severity of atherosclerotic lesions in theaortic roots as compared to those in the control group (57912mm2 and43706 mm2 vs. 89032 mm2, P<0.003). This effect was associated withsignificant reductions in plasma total (P<0.02) and LDL (P<0.03) cholesterolconcentrations as well as an increase in fecal cholesterol excretion(P<0.04). Furthermore, abdominal fat mass was significantlyreduced by consumption of aleurone (P<0.03). Corn fractions alsosignificantly increased antioxidant capacity as measured by DPPH(P<0.0003) and the activity of the CAT (P<0.01) and GPx (P<0.0001)while the activity of SOD (P<0.01) was decreased as compared with thecontrol mice. Current data suggest cholesterol-lowering and oxidativestress-lowering effects of corn fractions may be beneficial for the preventionof atherosclerotic CVD in LDL-r-KO mice. However, furtherstudies are necessary to understand other mechanisms of action. (Supportedby Canada Research Chair Grant; NSERC; BMO Financial GroupResearch Fellowship.