|Yokoyama, Wallace - Wally|
Submitted to: Journal of Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/4/2005
Publication Date: 2/1/2006
Citation: Davis, P., Valacchi, G., Pagnin, E., Shao, Q., Gross, H.B., Calo, L., Yokoyama, W.H. 2006. Walnuts Reduce Aortic ET-1 mRNA Levels in Hamsters Fed a High Fat, Atherogenic Diet. Journal of Nutrition. 0022-3166/06:428-432. Interpretive Summary: Walnut consumption has been shown to reduce the risk for cardiovascular disease, but the cause is unknown. We evaluated the role of high gamma tocopherol content in walnuts as a possible source of antioxidant activity using a hypercholesterolemic hamster model. We used an endothelial protein marker, ET-1, and plasma cholesterol esters in the aorta as markers for cardiovascular disease. Reference vitamin E diets of different concentrations were also fed to calibrate the antioxidant effect of gamma tocopherol. The results showed that the ET-1 in hamsters decreased with walnut consumption and that aortic cholesterol esters decreased with both increasing vitamin E intake and walnut consumption.
Technical Abstract: Walnut consumption is associated with CVD (coronary vascular disease) risk reduction, however the mechanisms responsible remain incompletely understood. Recent clinical studies suggest they involve nonlipid-related effects on endothelial function. Golden Syrian hamsters were fed for 26 weeks with either increasing walnuts (61 to 150 g/kg diet) or increasing 'T (alpha tocopherol) in a high fat hyperlipidemic diet. ET-1 (endothelin 1) was studied given its endothelial effects (plaque development, smooth muscle proliferation). Aortic CE (cholesterol ester), atherosclerosis measure, was highest in the lowest 'T group and declined with increasing 'T. Walnut groups’ aortic CE showed no specific dose response though all decreased relative to the lowest 'T’s CE. Conversely, aortic ET-1 was unaffected by increasing 'T but declined dramatically with increasing walnut consumption (max -75%). The results indicate that walnuts nonlipid-related CVD effects are not due to their tocopherol content, are mediated by ET-1-related effects on endothelial processes, the effects of walnut feeding noted in the human clinical study are consistent with ET-1 involvement and suggest CVD and other ET-1-related processes are likely to be altered by walnut consumption.