Platelet Selenium Indices as Useful Diagnostic Surrogate for Assessment of Selenium Status in Lambs: an Experimental Comparative Study on the Efficacy of Sodium Selenite vs. Selenium Nanoparticles.

Unlike in human medicine, information on the platelet selenium (Se) concentration and glutathione peroxidase (GPx) activity, as potential biomarkers of Se status, is lacking in the field of veterinary medicine. The aims of this study were to compare the effects of sodium selenite (SeS) and Se nanoparticles (SeN) on platelet Se indices, and compare the results with those of conventional indices of Se status in sheep. Eighteen lambs with marginal Se status were assigned to a control (CON) group and two Se-treated groups administered either a single dose of Se at 0.055 mg/kg BW subcutaneously as SeS or SeN. The Se concentration and GPx activity in plasma, erythrocytes, whole blood, and platelets were assessed at 14 time points during 90 days. In Se-treated groups, Se concentrations and GPx activity increased significantly in plasma, whole blood, erythrocytes, and platelets. However, the responses in SeS group often started and peaked earlier and, in almost all time points, were more pronounced than the SeN group (P < 0.001), indicating that SeS compared to SeN was more biopotent in raising Se biomarkers. Se indices in platelets started and peaked later than those of short-term (in plasma) and earlier than those of long-term indices (in erythrocytes) indicating that platelet indices can serve as intermediate-term biomarkers of Se status. In conclusion, platelet indices of Se are promising proxy for currently used indices of Se status in sheep, regardless of Se source.