Plasma diamine oxidase activity is greater in copper-adequate than copper-marginal or copper-deficient rats

The object of this study was to determine whether serum diamine oxidase act ivity could distinguish among adequate, marginal and deficient copper statu s in rats. Male weanling Sprague-Dawley rats (n = 21) were randomly assigne d to one of three dietary regimens, with copper concentrations of 0,52, 1,7 3 and 6.7 mg/kg diet. On completion of the study, body weights were signifi cantly different among dietary groups, with copper-marginal rats displaying the highest mean weight and copper-deficient rats the lowest. Copper-defic ient rats ate significantly less food than the other two groups. Rats fed t he three diets had significantly different liver copper concentrations. Liv er and heart superoxide dismutase and cytochrome c oxidase activities, and plasma ceruloplasmin and erythrocyte superoxide dismutase activities were s ignificantly lower in the copper-deficient rats than in the other two group s. Plasma diamine oxidase activity was lower in both copper-deficient (0.18 +/- 0.11 U/L) and marginal (0.21 +/- 0.11 U/L) rats compared with copper-a dequate rats (3.35 +/- 0.28 U/L), Of the biochemical indices measured, only liver copper concentration (-20%) and plasma diamine oxidase activity (-94 %) differed between rats fed copper-marginal and copper-adequate diets. Pla sma diamine oxidase activity, therefore, may be a sensitive functional biom arker of suboptimal copper status.