Effects of lead exposure on the expression of amyloid β and phosphorylated tau proteins in the C57BL/6 mouse hippocampus at different life stages

The objective of this study was to investigate the effects of lead exposure on spatial learning and memory capacity and the expression of amyloid β and phosphorylated tau proteins in the mouse hippocampus. A total of 24 adult C57BL/6 mice (12 of each sex) were mated at a 1:1 ratio. After delivery, the litters were normalised to 6 pups per litter. During the lactation period, the pups were randomly separated into four groups: control, early exposure, late exposure, or long-term exposure. These groups were not exposed to lead, exposed to lead from birth to week 24, exposed to lead from week 24 to week 48, or exposed to lead from birth to 48 weeks of age, respectively. Lead exposure was induced by providing Pb-contaminated drinking water at a concentration of 0.1%. All of the pups were fed until 72 weeks of age, at which time their spatial learning and memory capacity was evaluated via the Morris water maze test. Then, the lead levels in their blood and hippocampus were measured via graphite furnace atomic absorption spectrometry. The protein expression of amyloid β and phosphorylated tau in the hippocampus was detected via Western blot. The results revealed that the hippocampal and blood lead levels were significantly higher in all of the groups exposed to lead than the control group (P < 0.05). The spatial learning and memory performances of the lead-exposed groups were much poorer than those of the control group (P < 0.05). The expression levels of amyloid β and phosphorylated tau proteins were increased in the lead-exposed groups compared to the control group (P < 0.05). The enhanced expressions of amyloid β and phosphorylated tau proteins might contribute to the impairment in spatial learning and memory in the lead-exposed mice.     

The effects of early life Pb exposure on the expression of IL1-β, TNF-α and Aβ in cerebral cortex of mouse pups

ObjectiveTo investigate the effects of maternal lead (Pb) exposure on the learning and memory ability and expression of interleukin1-β (IL1-β), tumor necrosis factor (TNF-α) and beta amyloid protein (Aβ) in cerebral cortex of mice offspring.MethodsPb exposure initiated from beginning of gestation to weaning. Pb acetate administered in drinking solutions was dissolved in distilled deionized water at the concentrations of 0.1%, 0.5% and 1% groups, respectively. On the PND21, the learning and memory ability were tested by water maze test and the Pb levels were also determined by graphite furnace atomic absorption spectrometry. The expression of IL1-β, TNF-α and Aβ in cerebral cortex was measured by immunohistochemistry and western blotting.ResultsThe Pb levels in blood and cerebral cortex of all exposure groups were significantly higher than that of the control group (P < 0.05). In water maze test, the performances of 0.5% and 1% groups were worse than that of the control group (P < 0.05). The expression of IL1-β, TNF-α and Aβ was increased in Pb exposed groups than that of the control group (P < 0.05).ConclusionsThe high expression of IL1-β, TNF-α and Aβ in the cerebral cortex of pups may contribute to the impairment of learning and memory associated with maternal Pb exposure.     

Relationship of lead and essential elements in whole blood from school-age children in Nanning,China

ObjectivesThe aim of this study was to investigate blood lead level and its relationship to essential elements (zinc, copper, iron, calcium and magnesium) in school-age children from Nanning, China.MethodsA total of 2457 children aged from 6 to 14 years were enrolled in Nanning, China. The levels of lead (Pb), zinc (Zn), copper (Cu), iron (Fe), calcium (Ca) and magnesium (Mg) were determined by an atomic absorption spectrometer.ResultsThe mean blood lead level (BLL) was 57.21 ± 35.00 μg/L. 188 (7.65%) asymptomatic children had toxic lead level higher than 100 μg/L. The school-age boys had similar lead level among different age groups, while the elder girls had less BLL. The blood Zn and Fe were found to be increased in the boys with elevated BLL, but similar trends were not observed in the girls. Positive correlations between Pb and Fe or Mg (r = 0.112, 0.062, respectively, p < 0.01) and a negative correlation between Pb and Ca (r = −0.047, p < 0.05) were further established in the studied children.ConclusionsLead exposure in school-age children was still prevalent in Nanning. The boys and girls differed in blood levels of lead and other metallic elements. Lead exposure may induce metabolic disorder of other metallic elements in body.     

Effects of selenium compounds on proliferation and epigenetic marks of breast cancer cells

Breast cancer is a global public health problem and the most frequent cause of cancer death among women. Mammary carcinogenesis is driven not only by genetic alterations but also by epigenetic disturbances. Because epigenetic marks are potentially reversible they represent promising molecular targets for breast cancer prevention interventions. Selenium is a promising anti-breast cancer trace element that has shown the modulation of DNA methylation and histone post-translational modifications in other malignancies. This study aimed to evaluate the effects of selenium compounds [methylseleninic acid (MSA) and selenite] on cell proliferation and death, expression of the tumor suppressor gene RASSF1A and epigenetic marks in MCF-7 human breast adenocarcinoma cells. Treatment with MSA or selenite markedly inhibited (P < 0.05) in a dose-dependent manner the proliferation of MCF-7 cells. MSA induced (P < 0.05) G2/M cell arrest while selenite presented the opposite effect. Regarding cell death induction, MSA acted mainly by inducing apoptosis (P < 0.05), while selenite only induced necrosis (P < 0.05). Furthermore selenite, but not MSA, markedly induced (P < 0.05) cytotoxicity and increased (P < 0.05) RASSF1A expression. Both selenium compounds inhibited (P < 0.05) DNMT1 expression. MSA decreased (P < 0.05) H3K9me3 and increased (P < 0.05) H4K16ac, while selenite decreased (P < 0.05) this latter histone mark. To the best of our knowledge this is the first report showing that selenite and MSA modulate epigenetic marks specifically in breast cancer cells. Our data reinforce the anti-breast cancer potential of selenium that is dependent on its chemical form. Furthermore the data show that epigenetic mechanisms represent relevant molecular targets involved in selenium inhibitory effects in breast cancer cells.     

IGF-I mediated inhibition of leptin receptor expression in porcine hepatocytes

A study was conducted to elucidate hormonal control of leptin receptor gene expression in primary cultures of porcine hepatocytes. Hepatocytes were isolated from swine and seeded into T-25 flasks. Cultures were established in medium containing fetal bovine serum for one day and switched to serum-free medium (William's E medium and 1 ng/mL insulin) for the remainder of the 3 d culture period. For the final 24 h, medium was supplemented with porcine growth hormone (GH, 100 or 500 ng/mL), insulin-like growth factor 1 (IGF-1, 50 to 250 ng/mL) or triiodothyronine (T3, 100 ng/mL). RNA was extracted and relative quantitative RT-PCR was performed with primers for long form leptin receptor. Receptor expression was calculated relative to 18S rRNA. Insulin had no effect (P > 0.05), while T3 increased leptin receptor mRNA abundance (P < 0.05). Treatment with GH or IGF-I reduced leptin receptor expression (P < 0.05). Phosphorylation of ERK1/2 in response to acute leptin treatment was inhibited by previous exposure to GH or IGF-I. Hepatocytes secreted IGF-I under basal conditions and this was enhanced by GH addition. These data suggest porcine hepatocytes may be less sensitive to leptin stimulation due to the actions of endogenous IGF-I on leptin receptor expression.     

Fetal betamethasone exposure attenuates angiotensin-(1-7)-Mas receptor expression in the dorsal medulla of adult sheep

Glucocorticoids including betamethasone (BM) are routinely administered to women entering into early preterm labor to facilitate fetal lung development and decrease infant mortality; however, fetal steroid exposure may lead to deleterious long term consequences. In a sheep model of fetal programming, BM-exposed (BMX) offspring exhibit elevated mean arterial pressure (MAP) and decreased baroreflex sensitivity (BRS) for control of heart rate by 0.5-years of age associated with changes in the circulating and renal renin-angiotensin systems (RAS). In the brain solitary tract nucleus, angiotensin (Ang) II actions through the AT1 receptor oppose the beneficial actions of Ang-(1-7) at the Mas receptor for BRS regulation. Therefore, we examined Ang peptides, angiotensinogen (Aogen), and receptor expression in this brain region of exposed and control offspring of 0.5- and 1.8-years of age. Mas protein expression was significantly lower (>40%) in the dorsal medulla of BMX animals at both ages; however, AT1 receptor expression was not changed. BMX offspring exhibited a higher ratio of Ang II to Ang-(1-7) (2.30 ± 0.36 versus 0.99 ± 0.28; p < 0.01) and Ang II to Ang I at 0.5-years. Although total Aogen was unchanged, Ang I-intact Aogen was lower in 0.5-year BMX animals (0.78 ± 0.06 vs. 1.94 ± 0.41; p < 0.05) suggesting a greater degree of enzymatic processing of the precursor protein in exposed animals. We conclude that in utero BM exposure promotes an imbalance in the central RAS pathways of Ang II and Ang-(1-7) that may contribute to the elevated MAP and lower BRS in this model.     

Phosphate transporters expression in rice (Oryza sativa L.) associated with arbuscular mycorrhizal fungi (AMF) colonization under different levels of arsenate stress

It is known that arsenate and phosphate (P) share the same transporters in plants, and arbuscular mycorrhizal fungi (AMF) influence the expressions of Pi transporters (OsPT1–13) in rice. In order to study the effects of AMF on arsenate accumulation in rice, Glomus intraradices (AH01) was inoculated to rice and treated with different levels of arsenate (0, 2 and 8 μM). Results revealed that OsPT11 was increased whereas OsPT2 decreased (P < 0.05) in mycorrhizal plants. The increased expression of OsPT11 was one of the most important factors that led to the significantly higher P concentration (P < 0.05) in plant tissues, which compensated the down-regulation of OsPT2. The symbiosis of G. intraradices with rice slightly decreased (P > 0.05) the arsenate concentration in plant tissues but markedly enhanced (P < 0.05) plant biomass. The higher P content in mycorrhizal plants led to the higher P/As molar ratio (P < 0.05) and lower As uptake ratio (P < 0.05) in mycorrhizal plants treated by 2 μM arsenate. Mycorrhizal plants under such an arsenate treatment took up less As by per unit of root dry mass. The inoculation of G. intraradices was not able to transform the inorganic As to organic As. Further studies should be conducted focusing on the transport activities of each Pi transporter using yeast or oocyte expression system to identify which Pi transporters are responsible for the accumulation of arsenate.     

Apolipoprotein A-I inhibits chemotaxis,adhesion, activation of THP-1 cells and improves the plasma HDL inflammatory index

The anti-inflammatory effects of high density lipoprotein (HDL) are well described, however, such effects of Apolipoprotein A-I (ApoA-I) are less studied. Building on our previous study, we further explored the mechanism of anti-inflammatory effects of ApoA-I, and focused especially on the interaction between monocyte and endothelial cells and plasma HDL inflammatory index in LPS-challenged rabbits. Our results show that ApoA-I significantly decreased LPS-induced MCP-1 release from THP-1 cells and ox-LDL-induced THP-1 migration ratio (P < 0.01, respectively). ApoA-I significantly decreased sL-selectin, sICAM-1 and sVCAM-1 release (P < 0.01, P < 0.01, P < 0.05, respectively) from LPS-stimulated THP-1 cells. Furthermore, ApoA-I significantly inhibited LPS-induced CD11b and VCAM-1 expression on THP-1 cells (P < 0.01, P < 0.05, respectively). ApoA-I diminished LPS-induced mCD14 expression (P < 0.01) and NFκB nuclear translocation in THP-1 cells. After single dose treatment of ApoA-I, the value of plasma HDL inflammatory index in LPS-challenged rabbits was improved significantly (P < 0.05). These results suggest that ApoA-I can inhibit chemotaxis, adhesion and activation of human monocytes and improve plasma HDL inflammatory index with presenting beneficial anti-inflammatory effects.     

Expression of progesterone receptor membrane component (PGRMC) 1 and 2, serpine mRNA binding protein 1 (SERBP1) and nuclear progesterone receptor (PGR) in the bovine endometrium during the estrous cycle and the first trimester of pregnancy

Progesterone (P4) is involved in the regulation of essential reproductive functions affecting the target cells through both nuclear progesterone receptors (PGRs) and membrane progesterone receptors. The aim of this study was to determine the mRNA and protein expression for PGRMC1, PGRMC2, SERBP1 and PGR within the bovine endometrium during the estrous cycle and the first trimester of pregnancy. There were no changes in PGRMC1 and PGRMC2 mRNA and protein expression during the estrous cycle, however, mRNA levels of PGRMC1 and PGRMC2 were increased (P < 0.001) in pregnant animals. SERBP1 mRNA expression was increased (P < 0.05), while the level of this protein was decreased (P < 0.05) on days 11–16 of the estrous cycle. The expression of PGR mRNA was higher (P < 0.01) on days 17–20 compared to days 6–10 and 11–16 of the estrous cycle and pregnancy. PGR-A and PGR-B protein levels were elevated on days 1–5 and 17–20 of the estrous cycle as compared to other stages of the cycle and during pregnancy. In conclusion, our results indicate that P4 may influence endometrial cells through both genomic and nongenomic way. This mechanism may contribute to the regulation of the estrous cycle and provide protection during pregnancy.     

Effect of the exposure to methyl-β-cyclodextrin prior to chilling or vitrification on the viability of bovine immature oocytes

The present study aimed to evaluate the effect of methyl-β-cyclodextrin (MβCD) as a cholesterol loader to change oocyte plasma membrane and increase its tolerance toward cryopreservation. The first and second experiments were conducted to investigate if MβCD could improve nuclear and cytoplasmic maturation after oocyte exposure to cold stress for 10 or 30 min, respectively. No differences (P > 0.05) in either experiment in the metaphase II (MII) rate of oocytes exposed to MβCD and cold stress; but these oocytes presented lower maturation rates than control groups. In the second experiment, a lower percentage of oocytes showed degenerated chromatin (P < 0.05) after exposure to 2 mg/mL of MβCD compared to the group exposed to 0 mg/mL. However, no differences among treatments were observed in cytoplasmic maturation. Groups exposed to cold stress demonstrated a lower (P < 0.05) capacity for embryonic development compared to the control groups. In the third experiment immature oocytes were exposed to MβCD and then, vitrified (cryotop). After warming, we observed that the ability to reach MII and chromatin degeneration were altered (P < 0.05) by MβCD. The blastocysts rate (P < 0.05) on D7 was higher in the 2 mg/mL MβCD group, but an identical finding was not observed on D8 (P > 0.05). Chromatin degeneration was higher in the vitrification groups. We conclude that MβCD improved nuclear maturation by reducing oocyte degeneration after cold stress or vitrification; however, more studies are required to clarify the usefulness of MβCD use in oocyte cryopreservation.     

Fluctuations in energy-related metabolites during the peri-parturition period in Lori-Bakhtiari ewes

This study describes the fluctuations in serum energy-related metabolites during a period of 2 weeks before, to 2 weeks after parturition in Lori-Bakhtiari ewes. The effect of parity was also studied. Blood profiles were determined in 60 healthy pregnant ewes with single (n = 30) and twin (n = 30) lambings. Blood was collected from each ewe on days 14 and 7 prepartum, and days 7 and 14 postpartum to determine the serum non-esterified fatty acid (NEFA), β-hydroxybutyrate (BHBA), glucose, cholesterol, blood urea nitrogen (BUN) and calcium (Ca) levels. The age of the ewes had no significant effect on the energy metabolism indicators. Serum NEFA, BHBA, glucose, BUN and calcium concentrations recorded peak levels 7 days before parturition. However, NEFA and BHBA recorded significant changes (P < 0.05) during the peri-parturition period. All metabolites changed significantly in ewes carrying twin-bearing ewes, compared to single-bearing ewes. Serum BHBA concentrations recorded positive correlations with the serum NEFA (P < 0.01) and cholesterol (P < 0.05), while blood glucose had negative correlations (P < 0.01) with NEFA, BHBA and Ca. Blood NEFA and BHBA recorded positive correlations (P < 0.05) with the BUN levels and negative correlations (P < 0.05) with Ca. The results showed that blood NEFA and BHBA levels are sensitive indicators of the energy balance during the peri-parturition period in ewes.     

Fluoxetine, 17-β estradiol or folic acid combined with intra-lateral septal infusions of neuropeptide Y produced antidepressant-like actions in ovariectomized rats forced to swim

Folic acid is antidepressant, either alone or combined with several antidepressant drugs. However, the antidepressant-like actions of folic acid combined with intra-lateral septal (LSN) infusions of neuropeptide Y (NPY) in the forced swimming test (FST) have not been tested before. Thus, systemic injections of fluoxetine (20.0 mg/kg, P < 0.05; s.c.) or 17-β estradiol (10.0 μg/rat, P < 0.05; s.c.) or oral administrations of folic acid (50.0 mg/kg, P < 0.05; 75.0 mg/kg, P < 0.05) or NPY intra-LSN (3.0 μg, P < 0.05; 3.5 μg, P < 0.05) reduced immobility of ovariectomized Wistar rats. Subthreshold doses of: folic acid (25.0 mg/kg) or 17-β estradiol (5.0 μg/rat, P < 0.05) or fluoxetine (15.0 mg/kg, P < 0.05; s.c.) combined with subthreshold doses of NPY (2.5 μg/rat, P < 0.05; intra-LSN) and these combinations produced antidepressant-like actions; which were canceled by BIBP 3226 (a NPY-Y1 receptor antagonist). It is concluded that folic acid produced antidepressant-like effects probably through the participation of the NPY Y1 receptors found in the lateral septal nuclei.     

Expression of orexin receptors 1 (OX1R) and 2 (OX2R) in the porcine pituitary during the oestrous cycle

Orexin A and B, also termed hypocretin 1 and 2, are associated with the stimulation of food intake and arousal. The biological actions of the hormones are mediated via two distinct G protein-coupled receptors, termed orexin receptor 1 (OX1R) and orexin receptor 2 (OX2R). OX1R is selective for orexin A and OX2R binds orexin A and orexin B with similar affinity. The present study analyzed mRNA and protein expressions of OX1R and OX2R in adenohypophysis (AP) and neurohypophysis (NP) of cycling pigs. The tissue samples were harvested on days 2–3, 10–12, 14–16, and 17–19 of the oestrous cycle. Using quantitative real-time PCR higher OX1R gene expression was detected in AP on days 2–3 relative to days 10–12, 14–16 and 17–19 (p < 0.05). In NP the OX1R mRNA level was elevated on days 10–12 compared to the remaining stages (p < 0.05). OX2R gene expression in AP was the lowest on days 10–12 (p < 0.05 compared to days 2–3 and 17–19) and the expression peak occurred on days 17–19 (p < 0.05 vs. the all studied stages). In NP the highest (p < 0.05) expression of OX2R mRNA was noted on days 17–19 in relation to the remaining periods. OX1R protein content in AP was greatest on days 10–12 (p < 0.05), whereas in NP it was greatest on days 2–3 and 14–16 (p < 0.05 vs. days 10–12 and 17–19). In both cases the lowest OX1R protein expression was observed during follicular phase (p < 0.05 in relation to three remaining studied stages). OX2R protein in AP was lower (p < 0.05) on days 2–3 and 14–16 compared to days 10–12 and 17–19. In NP the lowest (p < 0.05) expression of this protein was on days 17–19 and the highest on days 10–12 (p < 0.05 compared to days 2–3 and 17–19). In summary, the present findings provide the first evidence that OX1R and OX2R mRNAs and proteins occur in the pituitary of the pig and indicate the dependence of orexin receptor expression on the endocrine reproductive state.