Tissue distribution of rare earth elements in wild, commercial and backyard rabbits.

Rare Earth Elements (REEs), La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, and Y, & two actinides, Th and U were assessed in muscle and liver tissues of wild, backyard and commercially raised rabbits through ICP-MS. Higher concentrations were found in liver in comparison to muscle tissue. Liver of wild rabbits accumulates all studied elements beyond Tm. Backyard rabbits do not show any statistically significant accumulation while commercial accumulate all beyond La, Ce, Pr, Nd, Gd and Tb. Wild rabbits were with the highest amounts for most of these elements. The different living and rearing environments of wild, backyard and commercial rabbits may affect accumulation, fate and transfer of REEs in rabbits' tissues. A dataset for establishing reference values of REEs in Lemnos island wild rabbits' is shown and the literature gap on safety limits for REEs is discussed.

Dietary organic selenium addition and accumulation of toxic and essential trace elements in liver and meat of growing rabbits.

The effects of dietary organic selenium (Se) addition at 0.1, 0.5 and 2.5 mg/kg vs. an unsupplemented basal diet (BD) on the accumulation of some toxic and essential trace elements were studied in the liver and muscle tissues of growing rabbits. Dietary Se addition increased liver and muscle Se concentration linearly (P < .001), and decreased linearly Cd, As, Ni and Cr (P < .001) in liver, as well as As (P < .01) and Cd (P < .001) in muscle. Muscle Cu and Zn contents were significantly lower (P < .05) in rabbits fed 2.5 mg Se/kg diet compared to the other 3 groups. Selenium was negatively correlated with Cr, Ni, Cd and As (P < .01) in liver, and with Cu (P < .05) and Cd (P < .01) in muscle. In conclusion, dietary Se supplementation decreased the accumulation of toxic (Cd and As) and potentially toxic (Cr and Ni) trace elements in rabbits. However, at excessive quantities may negatively affect essential trace elements.

The role of selenium in cadmium toxicity: interactions with essential and toxic elements.

1. The study was part of a project designed to investigate if organic selenium (Se) can ameliorate the toxic effects of cadmium (Cd). The main objective of the present study was to investigate, in the chicken, the interactions between Se, Cd and the following elements: Sb, Ca, Cr, Co, Cu, Fe, Pb, Mg, Mn, Mo, Ni, V and Zn. 2. A total of 300 1-d-old chickens (broilers) were randomly distributed among 4 dietary treatments with 5 replicate pens per treatment. In T1, chickens were fed on a diet with 0·3 mg/kg added Se, without added Cd. In T2, chickens were fed on a diet with 0·3 mg/kg Se and 10 mg/kg Cd. In T3, chickens were fed on a diet with 0·3 mg/kg Se and 100 mg/kg of Cd added and in T4 treatment, chickens were fed on a diet with 3 mg/kg Se and 100 mg/kg Cd added. Se was added as Se-yeast. Cd was added as cadmium chloride (CdCl2). On d 28 and 42, two chickens per replicate pen were killed for collection of whole blood, liver, kidney and breast muscle samples. Samples were analysed by ICP-MS. The data were analysed using a multivariate linear model. 3. While low Cd concentrations in the diet led only to an increase of Cd concentration in the examined tissues, addition of high concentrations of Cd increased the concentration of Cd, Cu, Sb and V and decreased that of Se, Mn and Fe. Addition of high Se concentrations did not significantly reduce Cd concentration. 4. Prior to model application, correlations of 78 elements were noted, while after model application 39 correlations were noted. Most notably, Cd was correlated with Ca, Co, Cu and Mg, while Se was correlated with Mn. 5. The present study revealed several correlations between essential, probably essential and toxic elements illustrating the importance of the balance between pro-oxidants and antioxidants.

Selenium affects the expression of GPx4 and catalase in the liver of chicken.

A total of 128 chickens (Gallus gallus, broilers) were used to investigate the effect of organic selenium (Se) in expression of catalase (CAT) and phospholipid hydroperoxidase 4 (GPx4) genes. There were 4 replicates of 4 dietary treatments: T1 (basal diet with no added Se), T2 (T1 with 0.15 ppm Se added), T3 (T1 with 0.3 ppm Se) and T4 (T1 with 3.0 ppm Se). At 4th and 6th week, 2 chickens per replicate pen were sacrificed for whole blood and liver sample collections. Samples were analyzed for total Se by ICP-MS and gene expression by RT-PCR. Dietary supplementation with organic Se (Se-yeast) readily elevated its concentration in the tissues. GPx4 mRNA levels, pooled for both ages, of chickens fed T3 and T4 diets were significantly reduced compared to those fed diet T1 by 47% and 77% respectively, while that of T2 did not differ. Liver CAT mRNA levels at 4th week were significantly decreased as Se supplementation increased, while at 6th week, were not significantly affected by Se. The study showed that liver GPx4 mRNA levels could be down-regulated by excess of Se. It is possible that reserves built by excess of Se meet antioxidant requirements and no additional GPx4 transcription is necessary.