Effect of Selenium Deficiency on Phosphorylation of the AMPK Pathway in Rats

Effects of nanoselenium supplementation on lactation performance, nutrient digestion and mammary gland development in dairy cows

The objective of this experiment was to evaluate the influence of nanoselenium (NANO-Se) addition on milk production, milk fatty acid synthesis, the development and metabolism regulation of mammary gland in dairy cows. Forty-eight Holstein dairy cows averaging 720 ± 16.8 kg of body weight, 66.9 ± 3.84 d in milk (dry matter intake [DIM]) and 35.2 ± 1.66 kg/d of milk production were divided into four treatments blocked by DIM and milk yields. Treatments were control group, low-Se (LSe), medium-Se (MSe) and high-Se (HSe) with 0, 0.1, 0.2 and 0.3 mg Se, respectively, from NANO-Se per kg dietary dry matter (DM). Production of energy- and fat-corrected milk (FCM) and milk fat quadratically increased (p < 0.05), while milk lactose yields linearly increased (p < 0.05) with increasing NANO-Se addition. The proportion of saturated fatty acids (SFAs) linearly decreased (p < 0.05), while proportions of monounsaturated fatty acids (MUFAs) linearly increased and polyunsaturated fatty acids (PUFAs) quadratically increased. The digestibility of dietary DM, organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) quadratically increased (p < 0.05). Ruminal pH quadratically decreased (p < 0.01), while total VFA linearly increased (p < 0.05) with increasing NANO-Se addition. The acetic to propionic ratio decreased (p < 0.05) linearly due to the unaltered acetic molar percentage and a quadratical increase in propionic molar percentage. The activity of CMCase, xylanase, cellobiase and pectinase increased linearly (p < 0.05) following NANO-Se addition. The activity of α-amylase increased linearly (p < 0.01) with an increase in NANO-Se dosage. Blood glucose, total protein, estradiol, prolactin, IGF-1 and Se linearly increased (p < 0.05), while urea nitrogen concentration quadratically decreased (p = 0.04). Moreover, the addition of Se at 0.3 mg/kg from NANO-Se promoted (p < 0.05) mRNA and protein expression of PPARγ, SREBP1, ACACA, FASN, SCD, CCNA2, CCND1, PCNA, Bcl-2 and the ratios of p-ACACA/ACACA and BCL2/BAX4, but decreased (p < 0.05) mRNA and protein expressions of Bax, Caspase-3 and Caspase-9. The results suggest that milk production and milk fat synthesis increased by NANO-Se addition by stimulating rumen fermentation, nutrients digestion, gene and protein expressions concerned with milk fat synthesis and mammary gland development.

Dietary sanguinarine supplementation recovers the decrease in muscle quality and nutrient composition induced by high-fat diets of grass carp (Ctenopharyngodon idella)

The intake of high-fat diets (HFD) has been shown to diminish the muscle quality of aquatic animals. Sanguinarine, as an excellent additive, exhibits the capability to reduce fat deposition and alleviate inflammation. However, its role in the muscle quality reduction caused by HFD remains unclear. An eight-week trial was conducted to investigate the impacts of dietary supplementation of sanguinarine at 1200 μg/kg (HFDS; crude fat = 10%) on the muscle quality of grass carp (Ctenopharyngodon idellus) in comparison to a basic diet (CON, crude fat = 5%). Each group had 3 replicates, with 40 fish per replicate. This experiment employed one-way ANOVA and Duncan's multiple comparisons of the means. The results showed that the HFD exhibited lower growth performance, reduced protein deposition, myofiber diameter, and muscle hardness, coupled with higher levels of fat deposition and inflammation when compared with the CON. However, HFDS improved growth performance (P < 0.05), fat metabolism (ppar-α ( P = 0.001), lpl (P < 0.001), atgl (P < 0.001), and cpt1 (P = 0.001) expression exhibited a significant elevation), protein deposition (the protein and mRNA levels of AKT (P = 0.004), PI3K (P = 0.027), TOR (P = 0.005), and P70S6K (P = 0.007) demonstrated a marked increase), myofiber diameter, muscle hardness, and the total content of eicosapentaenoic acid and docosahexaenoic acid. Furthermore, the HFDS reduced oxidative damage caused by fat deposition by significantly downregulating nf-κb (P < 0.001), il-1β (P < 0.001), il-6 (P < 0.001), il-8 (P = 0.003), and tnf-α (P < 0.001) expression and markedly upregulated nrf2 (P < 0.001), gpx4 (P < 0.001), cat (P < 0.001), sod (P < 0.001), and gr (P = 0.003) expression. The findings from this study suggest that sanguinarine has the potential to alleviate the adverse effects of HFD on growth and muscle quality, providing a theoretical foundation for its practical implementation.

Low Selenium and Low Protein Exacerbate Myocardial Damage in Keshan Disease by Affecting the PINK1/Parkin-mediated Mitochondrial Autophagy Pathway

OBJECTIVE

Keshan disease (KD) is a myocardial mitochondrial disease closely related to insufficient selenium (Se) and protein intake. PTEN induced putative kinase 1 (PINK1)/Parkin mediated mitochondrial autophagy regulates various physiological and pathological processes in the body. This study aimed to elucidate the relationship between PINK1/Parkin-regulated mitochondrial autophagy and KD-related myocardial injury.

METHODS

A low Se and low protein animal model was established. One hundred Wistar rats were randomly divided into 5 groups (control group, low Se group, low protein group, low Se + low protein group, and corn from KD area group). The JC-1 method was used to detect the mitochondrial membrane potential (MMP). ELISA was used to detect serum creatine kinase MB (CK-MB), cardiac troponin I (cTnI), and mitochondrial-glutamicoxalacetic transaminase (M-GOT) levels. RT-PCR and Western blot analysis were used to detect the expression of PINK1, Parkin, sequestome 1 (P62), and microtubule-associated proteins1A/1B light chain 3B (MAP1LC3B).

RESULTS

The MMP was significantly decreased and the activity of CK-MB, cTnI, and M-GOT significantly increased in each experimental group (low Se group, low protein group, low Se + low protein group and corn from KD area group) compared with the control group (P<0.05 for all). The mRNA and protein expression levels of PINK1, Parkin and MAP1LC3B were profoundly increased, and those of P62 markedly decreased in the experimental groups compared with the control group (P<0.05 for all).

CONCLUSION

Low Se and low protein levels exacerbate myocardial damage in KD by affecting the PINK1/Parkin-mediated mitochondrial autophagy pathway.

Dietary nano-Se supplementation regulates lipid deposition, protein synthesis and muscle fibre formation in grass carp fed with high-fat diet

The current study aims to confirm the positive effects of dietary nano-Se on nutrients deposition and muscle fibre formation in grass carp fed with high-fat diet (HFD) before overwintering and to reveal its possible molecular mechanism. The lipid deposition, protein synthesis and muscle fibre formation in grass carp fed with regular diet (RD), HFD or HFD supplemented with nano-Se (0·3 or 0·6 mg/kg) for 60 d were tested. Results show that nano-Se significantly reduced lipid content, dripping loss and fibre diameter (P < 0·05), but increased protein content, post-mortem pH24 h and muscle fibre density (P < 0·05) in muscle of grass carp fed with HFD. Notably, dietary nano-Se decreased lipid deposition in the muscle by regulating amp-activated protein kinase activity and increased protein synthesis and fibre formation in muscle by activating target of rapamycin and myogenic determining factors pathways. In summary, dietary nano-Se can regulate the nutrients deposition and muscle fibre formation in grass carp fed with HFD, which exhibit potential benefit for improving flesh quality of grass carp fed with HFD.

Selenium nanoparticles improve fish sperm quality by enhancing glucose uptake capacity via AMPK activation

Appropriate additives can provide a suitable physiological environment for storage of fish sperm and facilitate the large-scale breeding of endangered species and commercial fish. Suitable additives for fish sperm storage in vitro are required for artificial insemination. This study evaluate the effects of 0.1, 0.5, 1.5, and 4.5 mg/L selenium nanoparticles (SeNPs) on the quality of Schizothorax prenanti and Onychostoma macrolepis sperm storage in vitro at 4 °C for 72 h. We found that 0.5 mg/L SeNPs was a suitable concentration for maintaining the normal physiological state of O. macrolepis sperm during storage at 4 °C (p < 0.05). Higher adenosine triphosphate (ATP) content of O. macrolepis sperm before and after activation was present at that concentration. To further explore the potential mechanism of action of SeNPs on O. macrolepis sperm, western blotting and glucose uptake analyses were performed. The results implied that after 24 h of in vitro preservation, 0.5 mg/L SeNPs significantly improved p-AMPK levels and glucose uptake capacity of O. macrolepis sperm, while compound C (CC), the inhibitor of activated AMP-activated protein kinase (p-AMPK), significantly restricted the function of SeNPs on stored sperm. Similar effects of 0.5 mg/L SeNPs were found on Schizothorax prenanti sperm. Our study demonstrates that SeNPs maintained ATP content and O. macrolepis and Schizothorax prenanti sperm function during storage in vitro for 72 h, possibly because SeNPs enhanced the glucose uptake capacity of sperm by maintaining the level of p-AMPK.

Differential expression of cyclins CCNB1 and CCNG1 is involved in the chondrocyte damage of kashin-beck disease

The purpose of this study was clarify the relationship between the differential expression of cyclins CCNB1 and CCNG1 and chondrocyte damage in Kashin-Beck disease. Systematic review and high-throughput sequencing of chondrocytes derived from Kashin-Beck disease patients were combined to identify the differentially expressed cyclins and cyclin-dependent kinase genes. In parallel, weaned SD rats were treated with low selenium for 4 weeks and then T-2 toxin for 4 weeks. Knee cartilage was collected to harvest chondrocytes for gene expression profiling. Finally, the protein expression levels of CCNB1 and CCNG1 were verified in knee cartilage tissue of Kashin-Beck disease patients and normal controls by immunohistochemical staining. The systematic review found 52 cartilage disease-related cyclins and cyclin-dependent kinase genes, 23 of which were coexpressed in Kashin-Beck disease, including 15 upregulated and 8 downregulated genes. Under the intervention of a low selenium diet and T-2 toxin exposure, CCNB1 (FC = 0.36) and CCNG1 (FC = 0.73) showed a downward expression trend in rat articular cartilage. Furthermore, compared to normal controls, CCNB1 protein in Kashin-Beck disease articular cartilage was 71.98% and 66.27% downregulated in the superficial and middle zones, respectively, and 12.06% upregulated in the deep zone. CCNG1 protein was 45.66% downregulated in the superficial zone and 12.19% and 9.13% upregulated in the middle and deep zones, respectively. The differential expression of cyclins CCNB1 and CCNG1 may be related to articular cartilage damage in Kashin-Beck disease.

Selenium Deficiency Induces Pathological Cardiac Lipid Metabolic Remodeling and Inflammation

SCOPE

Selenium (Se) disequilibrium is closely involved in many cardiac diseases, although its in vivo mechanism remains uncertain. Therefore, a pig model was created in order to generate a comprehensive picture of cardiac response to dietary Se deficiency.

METHODS AND RESULTS

A total of 24 pigs were divided into two equal groups, which were fed a diet with either 0.007 mg/kg Se or 0.3 mg/kg Se for 16 weeks. Se deficiency caused cardiac oxidative stress by blocking glutathione and thioredoxin systems and increased thioredoxin domain-containing protein S-nitrosylation. Energy production was disordered as free fatty acids were overloaded, the tricarboxylic acid cycle was strengthened, and three respiratory chain proteins enhanced S-nitrosylation. Excess free fatty acids led to increased synthesis of diacylglycerol, phosphatidylcholine, and phosphatidylethanolamine, where the latter two are vulnerable to oxidation and caused an increase in malondialdehyde. Moreover, increased palmitic acid enhanced de novo ceramide synthesis and accumulation. Additionally, Se deficiency initiated inflammation via cytosolic DNA-sensing pathways, which activated downstream interferon regulatory factor 7 and nuclear factor kappa B.

CONCLUSIONS

The present study identified a lipid metabolic vulnerability and inflammation initiation pathways via Se deficiency, which may provide targets for human redox imbalance-induced cardiac disease treatment. This article is protected by copyright. All rights reserved.

Effect of Selenium Supplementation on Expression of SIRT1 and PGC-1α Genes in Ulcerative Colitis Patients: a Double Blind Randomized Clinical Trial

Selenium (Se) supplementation may decrease the severity of ulcerative colitis (UC) through the activation of genes responsible for immune modulation. The present research was aimed to assess the effect of Se supplementation on the expression of silent information regulator 1 (SIRT1) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) in UC patients. In a double-blind randomized parallel clinical trial, 100 patients with mild-to-moderate active UC met inclusion criteria and divided into 2 groups of treatment (50 patients received selenomethionine [200 µg daily]) and placebo (50 patients received placebo [1 capsule daily]) for 10 weeks. The expression rates of SIRT1 and PGC-1α were examined in the peripheral blood mononuclear cell (PBMC) using the real-time polymerase chain reaction. There was no considerable difference in the mean of baseline demographic and clinical characteristics between groups. Also, there were no significant differences in total energy intake, macronutrients, and micronutrients between groups. The SIRT1 gene expression in the Se group was significantly increased compared to the placebo (p < 0.001). An increase in the expression of the PGC-1α gene in the Se group was not statistically significant. It seems that Se supplementation caused a significant decrease in the inflammatory response of the colon by a significant increase in the expression of the SIRT1 gene.

Effects of selenium on the proliferation and apoptosis of sheep spermatogonial stem cells in vitro

The objective of this study was to investigate effects of selenium (Se) on proliferation and apoptosis of sheep spermatogonial stem cells (SSC) in vitro. The SSC were assigned to five treatment groups (0, 2.0, 4.0, 8.0 and 16.0 μmol/L Se). After treatment with Se for 96 h, cell proliferation and apoptosis were evaluated. The relative abundance of P53 mRNA transcript and protein, cell cycle and apoptosis-related genes were detected using real-time PCR and Western blot quantifications, respectively. The results indicate there were the least cell proliferation rates in the Se_16.0 group. Treatments with relatively greater Se concentrations (8.0 and 16.0 μmol/L) resulted in a greater percentage of apoptotic cells, which was consistent with the relative abundances of P53, P21, P27 and pro-apoptosis mRNA transcripts. There were relatively greater ROS concentrations in the control, Se_8.0 and Se_16.0 groups. Compared with the control group, treatment with the Se concentration of 16.0 μmol/L resulted in an increased abundance of P53, P21, P27 and BAX proteins. Treatment with Pifithrin-α suppressed the increase in abundance of P53 and P21 proteins induced by the relatively greater concentration of Se (16.0 μmol/L), however, did not result in a change in abundances of P27 and BAX proteins. These results indicate the regulatory functions of Se on proliferation and apoptosis of sheep SSC is associated with the P21-mediated P53 signalling pathway. The P27 and BAX proteins have limited functions during the apoptotic process of SSC induced by the relatively greater concentrations of Se.

Maternal selenium status is profoundly involved in metabolic fetal programming by modulating insulin resistance, oxidative balance and energy homeostasis

PURPOSE

High and low levels of selenium (Se) have been related to metabolic disorders in dams and in their offspring. Their relationship to oxidative balance and to AMP-activated protein kinase (AMPK) is some of the mechanisms proposed. The aim of this study is to acquire information about how Se is involved in metabolic programming.

METHODS

Three experimental groups of dam rats were used: control (Se: 0.1 ppm), Se supplemented (Se: 0.5 ppm) and Se deficient (Se: 0.01 ppm). At the end of lactation, the pups' metabolic profile, oxidative balance, Se levels, selenoproteins and IRS-1 hepatic expression, as well as hepatic AMPK activation were measured.

RESULTS

The experimental groups present deep changes in Se homeostasis, selenoproteins and IRS-1 hepatic expression, oxidative balance, AMPK activation ratio and insulin levels. They do, however, have different metabolic profiles.

CONCLUSIONS

High- and low-Se diets are linked to insulin resistance, yet the mechanisms involved are completely opposite.

Long-Term Selenium-Deficient Diet Induces Liver Damage by Altering Hepatocyte Ultrastructure and MMP1/3 and TIMP1/3 Expression in Growing Rats

The effects of selenium (Se)-deficient diet on the liver were evaluated by using growing rats which were fed with normal and Se-deficient diets, respectively, for 109 days. The results showed that rats fed with Se-deficient diet led to a decrease in Se concentration in the liver, particularly among male rats from the low-Se group. This causes alterations to the ultrastructure of hepatocytes with condensed chromatin and swelling mitochondria observed after low Se intake. Meanwhile, pathological changes and increased fibrosis in hepatic periportal were detected by hematoxylin and eosin and Masson's trichrome staining in low-Se group. Furthermore, through immunohistochemistry (IHC) staining, higher expressions of metalloproteinases (MMP1/3) and their tissue inhibitors of metalloproteinases (TIMP1/3) were observed in the hepatic periportal of rats from the low-Se group. However, higher expressions of MMP1/3 and lower expressions of TIMP1/3 were detected in hepatic central vein and hepatic sinusoid. In addition, upregulated expressions of MMP1/3 and downregulated expressions of TIMP1/3 at the messenger RNA (mRNA) and protein levels also appeared to be relevant to low Se intake. In conclusion, Se-deficient diet could cause low Se concentration in the liver, alterations of hepatocyte ultrastructure, differential expressions of MMP1/3 and TIMP1/3 as well as fibrosis in the liver hepatic periportal.

High Dietary Selenium Intake Alters Lipid Metabolism and Protein Synthesis in Liver and Muscle of Pigs

BACKGROUND

Prolonged high intakes of dietary selenium have been shown to induce gestational diabetes in rats and hyperinsulinemia in pigs.

OBJECTIVE

Two experiments were conducted to explore metabolic and molecular mechanisms for the diabetogenic potential of high dietary selenium intakes in pigs.

METHODS

In Expt. 1, 16 Yorkshire-Landrace-Hampshire crossbred pigs (3 wk old, body weight = 7.5 ± 0.81 kg, 50% males and 50% females) were fed a corn-soybean meal basal diet supplemented with 0.3 or 1.0 mg Se/kg (as selenium-enriched yeast for 6 wk). In Expt. 2, 12 pigs of the same crossbreed (6 wk old, body weight = 16.0 ± 1.8 kg) were fed a similar basal diet supplemented with 0.3 or 3.0 mg Se/kg for 11 wk. Biochemical and gene and protein expression profiles of lipid and protein metabolism and selenoproteins in plasma, liver, muscle, and adipose tissues were analyzed.

RESULTS

In Expt. 1, the 1-mg-Se/kg diet did not affect body weight or plasma concentrations of glucose and nonesterified fatty acids. In Expt. 2, the 3-mg-Se/kg diet, compared with the 0.3-mg-Se/kg diet, increased (P < 0.05) concentrations of plasma insulin (0.2 compared with 0.4 ng/mL), liver and adipose lipids (41% to 2.4-fold), and liver and muscle protein (10-14%). In liver, the 3-mg-Se/kg diet upregulated (P < 0.05) the expression, activity, or both of key factors related to gluconeogenesis [phosphoenolpyruvate carboxykinase (PEPCK); 13%], lipogenesis [sterol regulatory element binding protein 1 (SREBP1), acetyl-coenzyme A carboxylase (ACC), and fatty acid synthase (FASN); 46-90%], protein synthesis [insulin receptor (INSR), P70 ribosomal protein S6 kinase (P70), and phosphorylated ribosomal protein S6 (P-S6); 88-105%], energy metabolism [AMP-activated protein kinase (AMPK); up to 2.8-fold], and selenoprotein glutathione peroxidase 3 (GPX3; 1.4-fold) and suppressed (P < 0.05) mRNA levels of lipolysis gene cytochrome P450, family 7, subfamily A, polypeptide 1 (CYP7A1; 88%) and selenoprotein gene selenoprotein W1 (SEPW1; 46%). In muscle, the 3-mg-Se/kg diet exerted no effect on the lipid profiles but enhanced (P < 0.05) expression of P-S6 and mammalian target of rapamycin (mTOR; 42-176%; protein synthesis); selenoprotein P (SELP; 40-fold); and tumor suppressor protein 53 (P53) and peroxisome proliferator-activated receptor γ (PPARG; 52-58%; lipogenesis) and suppressed (P < 0.05) expression of INSR (59%; insulin signaling); selenoprotein S (SELS); deiodinases, iodothyronine, type I (DIO1); and thioredoxin reductase 1 (TXNRD1; 50%; selenoproteins); and ACC1 and FASN (35-51%; lipogenesis).

CONCLUSION

Our research showed novel roles, to our best knowledge, and mechanisms of high selenium intakes in regulating the metabolism of protein, along with that of lipid, in a tissue-specific fashion in pigs.