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

Selenium triggers Nrf2-AMPK crosstalk to alleviate cadmium-induced autophagy in rabbit cerebrum

Cadmium (Cd) is a toxic heavy metal that accumulates in the brain and causes a series of histopathological changes. Selenium (Se) exerts a crucial function in protecting damage caused by toxic heavy metals, but its potential mechanism is rarely studied. The main purpose of this study is to explore the protective effects of Se on Cd-induced oxidative stress and autophagy in rabbit cerebrum. Forty rabbits were randomly divided into four groups and treated as follows: Control group, Cd (1 mg/kg⋅BW) group, Se (0.5 mg/kg⋅BW) group and Cd (1 mg/kg⋅BW)+Se (0.5 mg/kg⋅BW) group, with 30 days feeding management. Our results suggested that Se treatment significantly suppressed the Cd-induced degenerative changes including cell necrosis, vacuolization, and atrophic neurons. In addition, Se decreased the contents of MDA and H₂O₂ and increased the activities of CAT, SOD, GST, GSH and GSH-Px, alleviating the imbalance of the redox system induced by Cd. Furthermore, Cd caused the up-regulation of the mRNA levels of autophagy-related genes (ATG3, ATG5, ATG7, ATG12 and p62), AMPK (Prkaa1, Prkaa2, Prkab1, Prkab2, Prkag2, Prkag3) and Nrf2 (Nrf2, HO-1 and NQO1) signaling pathway, and the expression levels of LC3II/LC3I, p-AMPK/AMPK, Beclin-1, Nrf2 and HO-1 proteins, which were alleviated by Se, indicated that Se inhibited Cd-induced autophagy and Nrf2 signaling pathway activation. In conclusion, our study found that Se antagonized Cd-induced oxidative stress and autophagy in the brain by generating crosstalk between AMPK and Nrf2 signaling pathway.

Multi-Element Determination of Toxic and Nutrient Elements by ICP-AES after Dispersive Solid-Phase Extraction with Modified Graphene Oxide

A novel graphene-oxide-derived material was synthesized after modification of graphene oxide with sodium hydroxide and used for the dispersive solid-phase extraction (d-SPE) of different elements (Pb, Cd, Ba, Zn, Cu and Ni) prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). The prepared nanomaterial was characterized by X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. Full factorial design and Derringer’s type desirability function were used for the optimization of the d-SPE procedure. Pareto charts illustrated the effects of each of the examined factors and their interactions on the determination of the elements. Under the optimum conditions, detection limits (LODs) for the elements ranged between 0.01 and 0.21 μg g−1, intra-day repeatability (n = 5) was lower than 1.9% and inter-day repeatability (n = 5 × 3) was lower than 4.7%. Relative recovery values ranged between 88.1 and 117.8%. The method was validated and successfully applied for the determination of trace elements in poultry, pork and beef samples from the local market. The proposed method is simple, rapid, sensitive and the novel sorbent can be used at least ten times.

Selenium-enriched Saccharomyces cerevisiae improves the meat quality of broiler chickens via activation of the glutathione and thioredoxin systems

The aim of this study was to investigate the effects of selenium (Se)-enriched Saccharomyces cerevisiae (SSC) on meat quality and to elucidate the underlying mechanisms in broilers. A total of 200 one-day-old Arbor Acres broiler chickens were randomly allocated to one of four treatments with 5 replications of 10 chickens each. Group 1 served as a control and was fed a basal diet without Se supplementation, while groups 2, 3, and 4 were fed the basal diet supplemented with S. cerevisiae (SC), sodium selenite (SS), and SSC, respectively. Breast muscle samples were collected to evaluate meat quality, selenium concentration, oxidative stability, and the mRNA levels of antioxidant enzyme genes on day 42. As compared with groups 1 and 2, SS and SSC supplementation increased Se concentration, glutathione peroxidase (GPx) and thioredoxin reductase (TR) activities, total antioxidant capacity, and the mRNA levels of GPx-1, GPx-4, TR-1, and TR-3 (P < 0.05) and decreased drip loss and malondialdehyde (MDA) content (P < 0.05). As compared with group 3, SSC supplementation increased pH, lightness, yellowness, Se concentration, GPx and superoxide dismutase activities, and the mRNA levels of GPx-1 and GPx-4 (P < 0.05) but decreased drip loss and MDA content (P < 0.05). Thus, SSC improved meat quality and oxidative stability by activating the glutathione and thioredoxin systems, which should be attributed to the combined roles of Se and SC.

The Effects of Low Selenium on DNA Methylation in the Tissues of Chickens

DNA methylation is involved in epigenetic mechanisms associated with gene suppression, and its abnormalities lead to gene instability and disease development. As an essential trace element in humans and animals, selenium (Se) is also associated with abnormal changes in DNA methylation. However, the effect of low Se on DNA methylation in avian tissues has not been reported. In the current study, chickens were fed a low-Se diet (0.033 mg Se/kg) or supplemented with 0.15 mg Se/kg as selenite for up to 55 days. DNA methylation levels were examined by high-performance liquid chromatography (HPLC). DNA methyltransferases (DNMTs) and methyl-DpG-binding domain protein 2 (MBD2) mRNA levels were examined through the applications of RT-PCR. The experiment aims to explore the relationship between low Se and DNA methylation. The results showed that total DNA methylation levels in the muscle tissues, brain, immune tissues, and liver of the low-selenium diet group were decreased compared with the control group. The degree of DNA methylation reduction in different tissues from largest to smallest was liver > cerebellum > thymus > brain > spleen ≥ leg muscles > pectoral muscles > bursa of Fabricius > thalamus > wing muscles. DNMT1, DNMT3A, and DNMT3B mRNA expression levels of the low-selenium diet group were decreased compared with those in the control group. The mRNA expression of the MBD2 gene was increased. The results indicate that low Se can reduce the DNA methylation levels of tissues, especially within the liver. These conclusions provide a basis for exploring the pathogenesis of selenium deficiency from the perspective of DNA methylation and create a new basis for comparative medicine.

Avian Stress-Related Transcriptome and Selenotranscriptome: Role during Exposure to Heavy Metals and Heat Stress

Selenium, through incorporation into selenoproteins, is one of the key elements of the antioxidant system. Over the past few years there has been increased interest in exploring those molecular mechanisms in chicken, responsible for the development of this protection system. In more detail, Cd/Pb poisoning and heat stress increase oxidation, mRNA levels of inflammatory proteins, and apoptotic proteins. Selenium seems to enhance the antioxidant status and alleviates these effects via upregulation of antioxidant proteins and other molecular effects. In this review, we analyze avian transcriptome key elements with particular emphasis on interactions with heavy metals and on relation to heat stress.

Blood and hair as non-invasive trace element biological indicators in growing rabbits

<p>The suitability of blood and hair as non-invasive tools to monitor trace element contents was studied in 48 Hyla male growing rabbits. Three diets with increasing organic selenium (Se) addition (0.1, 0.5 and 2.5 mg/kg) were used to induce alterations in the concentrations of trace elements vs. an unsupplemented diet. In blood, a linear decrease in Co (P&lt;0.001), Cu (<em>P</em>&lt;0.001), Mn (<em>P</em>&lt;0.05), Zn (<em>P</em>&lt;0.05), Sb (<em>P</em>&lt;0.001), As (<em>P</em>&lt;0.001), Cr (<em>P</em>&lt;0.001), Mo (<em>P</em>&lt;0.001), Ni (<em>P</em>&lt;0.001) and Cd (<em>P</em>&lt;0.001) concentrations with increasing dietary Se was observed. In hair, a cubic effect of dietary Se on Co (<em>P</em>&lt;0.01), Cu (<em>P</em>&lt;0.05), Mn (<em>P</em>&lt;0.001), Pb (<em>P</em>&lt;0.05), Mo (<em>P</em>&lt;0.05) and Cd (<em>P</em>&lt;0.05) concentrations was found, while As, Cr and Ni concentrations decreased linearly (<em>P</em>&lt;0.01, <em>P</em>&lt;0.01 and <em>P</em>&lt;0.001, respectively) with increasing dietary Se. Selenium was negatively correlated to Sb, As, Cr, Mo, Ni and Cd, (P&lt;0.001) in blood, and to As (<em>P</em>&lt;0.05), Cr, Ni (<em>P</em>&lt;0.01) and Pb (P&lt;0.05) in hair. The contents of Se, As, Cr and Ni in blood were highly correlated (<em>P</em>&lt;0.001) to those in hair. Blood appeared to be more sensitive than hair in detecting small changes in the trace element profile in rabbits, as was indicated by the discriminant analysis. In conclusion, blood and hair can be suitable biological indicators of essential, toxic and potentially toxic trace element status in rabbits, particularly when used complementarily.</p>