Plasma Diamine Oxidase Activity Is Greater in Copper-Adequate than Copper-Marginal or Copper-Deficient Rats

Abstract

The object of this study was to determine whether serum diamine oxidase activity could distinguish among adequate, marginal and deficient copper status in rats. Male weanling Sprague-Dawley rats (n = 21) were randomly assigned to one of three dietary regimens, with copper concentrations of 0.52, 1.73 and 6.7 mg/kg diet. On completion of the study, body weights were significantly different among dietary groups, with copper-marginal rats displaying the highest mean weight and copper-deficient rats the lowest. Copper-deficient rats ate significantly less food than the other two groups. Rats fed the three diets had significantly different liver copper concentrations. Liver and heart superoxide dismutase and cytochrome c oxidase activities, and plasma ceruloplasmin and erythrocyte superoxide dismutase activities were significantly lower in the copper-deficient rats than in the other two groups. 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-adequate 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. Plasma diamine oxidase activity, therefore, may be a sensitive functional biomarker of suboptimal copper status.

Demonstration of a Hyperglycemia-Driven Pathogenic Abnormality of Copper Homeostasis in Diabetes and Its Reversibility by Selective Chelation

“…Normally, Ն95% of plasma Cu is ceruloplasmin bound, and levels of circulating Cu and ceruloplasmin are closely related (19). These are the biomarkers most frequently used as measures of Cu status, and both are depressed in severe Cu deficiency (20). However, levels plateau when Cu intake is adequate and do not reflect the magnitude of Cu intake beyond this point, so they are not useful for characterizing Cu excess states (21).…”

The effect of copper deficiency on the formation of hemosiderin in sprague-dawley rats

“…Although, 0.7 mg of copper is significantly less copper than the control group received, it may have been enough to allow the rats to grow well for 60 days. However, the rats fed a copperdeficient diet were indeed copper-deficient, as indicated by both their decreased concentration of hepatic copper (Table 2) and their lack of p-phenylenediamine oxidase activity in their sera, which is a good indication of the copper status of the animals (Kehoe et al 2000), because the primary enzyme responsible for oxidizing p-phenylenediamine in serum is the coppercontaining enzyme ceruloplasmin (Ravin 1961).…”

Present situation of biomarkers for copper status

“…Animal and human studies have shown that plasma diamine oxidase (DAO) activity is reduced in mild copper deficiency (4,5). However, tissue injury may also increase plasma DAO activity, thus confounding its interpretation.…”