Selenium-Alleviated Testicular Toxicity by Modulating Inflammation, Heat Shock Response, and Autophagy Under Oxidative Stress in Lead-Treated Chickens.

Lead (Pb), a toxic pollutant, is toxic to the testis. However, biological events during testicular Pb poisoning were not well understood. Selenium (Se) has the ability to antagonize Pb toxicity. The purpose of this research was to clarify the relief mechanism of Se on testicular toxicity of Pb from the perspective of oxidative stress, inflammation, heat shock response, and autophagy in a chicken model. Sixty male Hyline chickens (7-day-old) were randomly assigned into four groups. The feeding program consisted of a commercial diet, a Se-supplemented diet (1 mg kg-1 Se), a Pb-supplemented diet (350 mg L-1 Pb), and a Se- and Pb-supplemented diet, respectively. On the 12th week, serums were collected to measure testosterone level and testes were removed to determine testis weight, histological structure, Pb and Se concentrations, oxidative stress indicators, and mRNA and protein expression of inflammatory cytokines, heat shock proteins, and autophagy-related genes. The results showed that Pb poisoning changed the histological structure of testes; decreased serum testosterone level, testis weight, catalase, glutathione-s-transferase, and total antioxidative capacity activities; increased hydrogen peroxide content; inhibited interleukin (IL)-2 and mammalian target of rapamycin expression; and promoted IL-4, IL-12ß, heat shock proteins, Beclin 1, Dynein, autophagy-related proteins 5, light chain 3 (LC3)-I, and LC3-II expression in the testes of chickens. Se intervention mitigated the aforementioned alterations induced by Pb. In conclusion, Pb led to oxidative stress, which triggered inflammation, heat shock response, and autophagy. Se administration mitigated testicular toxicity of Pb mainly by mitigating oxidative stress in male chickens.

A potential mechanism associated with lead-induced spermatogonia and Leydig cell toxicity and mitigative effect of selenium in chicken.

Lead (Pb) is a toxic heavy metal pollutants and can damage male reproductive function. Selenium (Se) possesses an ability of antagonizing Pb toxicity. However, biological events in the process of Pb toxicity and mitigative effect of Se are not well understood. The aim of present research was to investigate potential mechanism of Se against Pb toxicity from the perspective of oxidative stress, heat shock response and autophagy in the spermatogonia and Leydig cell of chicken. The cells from one-day-old male Hyline chickens were treated with Se (0.5 µmol/L) and/or Pb (20 µmol/L) for 24 h, respectively. Cell viability, cell ultrastucture, Pb and Se concentrations, testosterone level, oxidative stress indicators and relative expression of heat shock proteins (HSPs) and autophagy-related genes were measured. The results showed that spermatogonia was more tolerant to Pb than Leydig cell; cell injury was confirmed via histological assessment, cell viability and testosterone level; oxidative stress was further indicated by the decrease of catalase, glutathione peroxidase, glutathione-s-transferase and superoxide dismutase activities and the increase of malondialdehyde and reactive oxygen species contents. Pb increased expression of HSPs (27, 40, 60, 70 and 90). Meanwhile Pb induced autophagy through up-regulation of autophagy-related proteins 5, Beclin 1, Dynein, light chain 3 (LC3)-I and LC3-II and down-regulation of mammalian target of rapamycin in two type cells of chicken. However, Se intervention mitigated the aforementioned alterations caused by Pb. In conclusion, Pb led to oxidative stress, which triggered heat shock response and autophagy; Se administration mitigated reproductive toxicity of Pb through strengthening antioxidant defense in the spermatogonia and Leydig cell of chicken.

Epigenetic and SP1-mediated regulation is involved in the repression of galactokinase 1 gene in the liver of neonatal piglets born to betaine-supplemented sows.

PURPOSE: In this study, we sought to investigate the effects of maternal betaine supplementation on the expression and regulation of GALK1 gene in the liver of neonatal piglets. METHODS: Sixteen sows of two groups were fed control or betaine-supplemented diets (3 g/kg), respectively, throughout the pregnancy. Newborn piglets were individually weighed immediately after birth, and one male piglet close to mean body weight from the same litter was selected and killed before suckling. Serum samples of newborn piglets were analyzed for biochemical indexes, hormone and amino acid levels. Liver samples were analyzed for GALK1 expression by real-time PCR and western blotting, while GALK1 regulational mechanism was analyzed by methylated DNA immunoprecipitation, chromatin immunoprecipitation and microRNAs expression. RESULTS: Betaine-exposed neonatal piglets had lower serum concentration of galactose, which was associated with significantly down-regulated hepatic GALK1 expression. The repression of GALK1 mRNA expression was associated with DNA hypermethylation and more enriched repression histone mark H3K27me3 on its promoter. Binding sites of SP1, GR and STAT3 were predicted on GALK1 promoter, and decreased SP1 protein content and lower SP1 binding to GALK1 promoter were detected in the liver of betaine-exposed piglets. Furthermore, the expression of miRNA-149 targeting GALK1 was up-regulated in the liver of betaine-exposed piglets, along with elevated miRNAs-processing enzymes Dicer and Ago2. CONCLUSIONS: Our results suggest that maternal dietary betaine supplementation during gestation suppresses GALK1 expression in the liver of neonatal piglets, which involves complex gene regulation mechanisms including DNA methylation, histone modification, miRNAs expression and SP1-mediated transcriptional modulation.

Maternal Betaine Supplementation throughout Gestation and Lactation Modifies Hepatic Cholesterol Metabolic Genes in Weaning Piglets via AMPK/LXR-Mediated Pathway and Histone Modification.

Betaine serves as an animal and human nutrient which has been heavily investigated in glucose and lipid metabolic regulation, yet the underlying mechanisms are still elusive. In this study, feeding sows with betaine-supplemented diets during pregnancy and lactation increased cholesterol content and low-density lipoprotein receptor (LDLR) and scavenger receptor class B type I (SR-BI) gene expression, but decreasing bile acids content and cholesterol-7a-hydroxylase (CYP7a1) expression in the liver of weaning piglets. This was associated with the significantly elevated serum betaine and methionine levels and hepatic S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) content. Concurrently, the hepatic nuclear transcription factor liver X receptor LXR was downregulated along with activated signal protein AMP-activated protein kinase (AMPK). Moreover, a chromatin immunoprecipitation assay showed lower LXR binding on CYP7a1 gene promoter and more enriched activation histone marker H3K4me3 on LDLR and SR-BI promoters. These results suggest that gestational and lactational betaine supplementation modulates hepatic gene expression involved in cholesterol metabolism via an AMPK/LXR pathway and histone modification in the weaning offspring.

Maternal betaine supplementation during gestation modifies hippocampal expression of GR and its regulatory miRNAs in neonatal piglets.

Methyl donor nutrients are critical for embryonic development of brain. Hippocampus is the most susceptible brain region to various factors including prenatal supply of methyl donors. Glucocorticoid receptor (GR) expressed in hippocampus is involved in the regulation of energy homeostasis and stress sensitivity. Hippocampal GR expression is highly susceptible to epigenetic regulation, yet the effect of maternal methyl donor supplementation on epigenetic regulation of GR transcription in offspring hippocampus remains unclear. In this study, we fed sows with betaine (3 g/kg) throughout the gestation and analyzed the hippocampal expression of GR mRNA and its variants, as well as the CpG methylation status of the promoter and the microRNAs predicted to target 3' UTR of porcine GR gene in neonatal piglets. Total GR mRNA (P<0.01) and its variants GR 1-4 (P<0.05) and 1-9,10 (P<0.01), were significantly higher in the hippocampus of betaine-treated piglets, while the content of GR protein was not significantly changed. The CpGs located in the -1650 ~ -1515 segment of GR gene were hypermethylated (P<0.05). The hippocampal expression of miR-130b (P<0.05), miR-181a (P<0.05) and miR-181d (P<0.01) was significantly up-regulated. The targeting efficacy of miR-130b and miR-181d was validated in vitro using dual-luciferase reporter assay system. Our results demonstrate that maternal betaine supplementation during gestation enhances GR mRNA expression in offspring hippocampus, which involves alterations in miRNAs expression.