Comparative Analysis of Selected Biochemical Markers Involved in Antioxidative, Immune Responses, and Thyroid Function in Wistar Rats Fed Diets Containing Baked Sprats

Objective: This study was designed to evaluate the effect of baked freeze-dried sprats (SPR) added to experimental diets of Wistar rats, with induced streptozotocin (STZ) oxidative stress, on selected biochemical markers involved in antioxidative, immune responses, and thyroid function. Material and Methods: Male Wistar rats (n = 48) were assigned to four experimental groups: C control group, STZ group of rats injected with streptozotocin, SPR group fed diet containing sprats, and STZ + SPR group. Concentrations of selected minerals were determined in urine, feces and selected organs. Serum thyroid hormones (T3, T4), a thyroid-stimulating hormone (TSH) concentration, and the activity of antioxidant enzymes (GPx, GR, SOD) were assessed. The relative expression of Txnrd1, Gpx1/3, Dio1–3 was quantified. Results: The highest concentrations of Mg, I, and Se were observed in the liver of the SPR and STZ + SPR groups compared with the C and STZ groups. T4 was significantly higher in all experimental groups compared to the C group. mRNA Txnrd1 expression was higher in the thyroid of the SPR and STZ + SPR groups than in the C and STZ groups. The thyroid in STZ + SPR exhibited higher Dio1 with lower Dio2 and Dio3 expression. Conclusions: It can be concluded that baked sprats are the source of bioavailable minerals involved in the reduction of oxidative stress and the modulation of iodine metabolism in rats with oxidative stress caused by impaired glucose metabolism.