Health of herring gulls (Larus argentatus) in relation to breeding location in the early 1990s. III. Effects on the bone tissue

Xanthohumol Effect on 2,3,7,8-Tetrachlorodibenzo-p-dioxin-Treated Japanese Quails in Terms of Serum Lipids, Liver Enzymes, Estradiol, and Thyroid Hormones

Dioxins are compounds classified as persistent organic pollutants, from which 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is the most toxic to living organisms. TCDD is considered a carcinogen and has proinflammatory influence on animals and humans, promoting free radicals' formation, and binding with the aryl hydrocarbon receptor (AhR) leads to expression of cytochrome p-450 genes that in turn predisposes to mutations. Natural flavonoids, in this case xanthohumol (XN), have been reported to attenuate TCDD toxicity through inhibition of the transformation of the AhR. Moreover, XN shows antioxidant properties. The aim of the study was to compare the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin and XN on lipid, liver enzyme, estradiol, and thyroid enzyme levels in the serum of Japanese quails. Adult, six-month-old, Japanese quails were divided into eight groups according to treatment procedures. Serum levels of total cholesterol (TCh), high-density lipoproteins (HDLs), triglycerides (TGs), estradiol, triiodothyronine, and thyroxine, and activities of alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase were measured. In comparison with the control group, 2,3,7,8-tetrachlorodibenzo-p-dioxin significantly decreased concentrations of serum HDLs and thyroid hormones and significantly increased the serum TCh level. Levels of serum TGs, liver enzymes, and estradiol were not changed after 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment. Based on our data, XN treatment may also increase the levels of thyroid hormones. Moreover, the tested dioxin disrupts the liver function, especially changing lipids' metabolism. Therefore, more studies are needed for better understanding the mechanism of toxic influence of 2,3,7,8-tetrachlorodibenzo-p-dioxin on key metabolic pathways and organs in living organisms.

The Protective Effect of α-Tocopherol on the Content of Selected Elements in the Calvaria for Exposed Hens to TCDD in the Early Embryonic Period

This paper focuses on negative effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on element content in male chicken calvaria and α-tocopherol (vitamin E) ability to reduce its toxic potential on bone mineralization in offspring. In the experiment carried out once, a solution containing only DMSO, TCDD, TCDD + α-tocopherol, and exclusively α-tocopherol was administrated. Subsequently, on the 5th day after hatching, the mineral composition of the chicken calvaria was evaluated. The results obtained suggest that the use of α-tocopherol contributes to the maintenance of the concentration of calcium, magnesium, and manganese in the chicken calvaria treated with TCDD in the embryonic period. In turn, vitamin E increases the level of zinc. It has been found that α-tocopherol in chicken embryos has a protective effect against disturbance of level of chosen trace elements in the bones of offspring caused by the TCDD.

Indirect study of the effect of α-tocopherol and acetylsalicylic acid on the mineral composition of bone tissue in the offspring of female rats treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin: long-term observations

This paper discusses problems related to the influence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the mineral composition of the calvaria in the offspring of female rats.

Bone density and asymmetry are not related to DDT in House Sparrows: Insights from micro-focus X-ray computed tomography

In organisms, DDT (Dichlorodiphenyltrichloroethane) and its metabolites, DDE (Dichlorodiphenyldichloroethylene) and DDD (Dichlorobischlorophenylethane) are endocrine mimics. They can influence bone density and other bone structural features. This study was conducted on House Sparrows (Passer domesticus) caught from the Free State - and the Limpopo Provinces of South Africa (SA). The sites were chosen based on spraying patterns of DDT for malaria control or non-spraying. The bone mineral densities of the femurs as well as the lengths of the left- and right leg bones were determined using micro-focus X-ray computed tomography (μ-XCT). The concentrations of DDT and its metabolites in the liver were determined with gas-chromatography mass-spectrometry to provide baseline concentrations of DDT in the body, allowing comparison of the various groups of birds. There was no asymmetry between the lengths of the bones of the left- and the right legs. DDT concentrations in the liver did not correlate with bone lengths. In addition, there were no significant differences between the relative densities of the left- and right leg bones with increase of concentrations of DDT. The concentrations of DDT and its metabolites did not have a significant effect on the measured bone parameters of House Sparrows. It is possible that the concentrations of DDT and its metabolites in the environments were too low to be injurious to the birds and/or tolerance to the insecticide has developed in the birds over more than six decades of almost continuous application of DDT.

Low-dose developmental exposure to bisphenol A induces sex-specific effects in bone of Fischer 344 rat offspring

BACKGROUND

Bisphenol A (BPA) is a component of polycarbonate plastics to which humans are regularly exposed at low levels, and an endocrine disruptor with effects on several hormonal systems. Bone is a sensitive hormone target tissue, and we have recently shown that in utero and lactational exposure to 25µg BPA/kg BW/day alters femoral geometry in rat offspring.

OBJECTIVE

To investigate bone effects in rat offspring after developmental exposure to a BPA dose in the range of human daily exposure (0.1-1.5µg/kg BW/day) as well as a dose to corroborate previous findings.

METHODS

Pregnant Fischer 344 rats were exposed to BPA via drinking water corresponding to 0.5µg/kg BW/day: [0.5], (n=21) or 50µg/kg BW/day: [50], (n = 16) from gestational day 3.5 until postnatal day 22, while controls were given only vehicle (n = 25). The offspring was sacrificed at 5 weeks of age. Bone effects were analyzed using peripheral quantitative computed tomography (pQCT), the 3-point bending test, plasma markers of bone turnover, and gene expression in cortical bone and bone marrow.

RESULTS

Compared to controls, male offspring developmentally exposed to BPA had shorter femurs. pQCT analysis revealed effects in the [0.5] group, but not in the [50] group; BPA reduced both trabecular area (-3.9%, p < 0.01) and total cross sectional area (-4.1%, p < 0.01) of femurs in the [0.5] group, whereas no effects were seen on bone density. Conversely, bone length and size were not affected in female offspring. However, the procollagen type I N-terminal propeptide (P1NP), a peptide formed during type 1 collagen synthesis, was increased in plasma (42%: p < 0.01) in female offspring exposed to [0.5] of BPA, although collagen gene expression was not increased in bone. The biomechanical properties of the bones were not altered in either sex. Bone marrow mRNA expression was only affected in male offspring.

CONCLUSIONS

Developmental low-dose exposure to BPA resulted in sex-specific bone effects in rat offspring. A dose approximately eight times lower than the current temporary EFSA human tolerable daily intake of 4µg/kg BW/day, reduced bone length and size in male rat offspring. Long-term studies are needed to clarify whether the increased plasma levels of P1NP in female offspring reflect development of fibrosis.

Alterations in geometry, biomechanics, and mineral composition of juvenile rat femur induced by nonplanar PCB-155 and/or planar PCB-169

Exposure to widespread lipophilic and bioaccumulative polychlorinated biphenyls (PCBs) induces diverse biochemical and toxicological responses in various organs, including the bone. The aim of this study was to evaluate the changes in growth rate, geometry, serum, and bone biochemical parameters and biomechanics of juvenile rat femur induced by lactational exposure to nonplanar PCB-155 and planar PCB-169 individually and in combination. Fifteen lactating Wistar rats were divided into four groups (PCB-169, PCB-155, PCB-155+169, and control), and PCBs were administered intraperitoneally at different time points after delivery. Femurs from 22-day-old offspring were analyzed by microCT, three-point bending test and inductively coupled plasma-mass spectrometry (ICP-MS) to obtain data on bone geometry, biomechanics and mineral composition. The serum levels of calcium, phosphate and alkaline phosphatase were also determined. Lactational exposure to planar PCB-169 resulted in shorter and thinner femurs, reduced endosteal and periosteal perimeters, smaller total cross-sectional and medullary areas, and lowered serum bone marker levels and calcium levels in the bone, while femur mechanical properties were not significantly altered. The changes observed in the combination exposure (PCB-155+169) group were similar to those observed in the PCB-169 group but were less pronounced. In summary, our results demonstrate that alterations in lactationally exposed offspring were primarily induced by planar PCB-169. The milder outcome in the combined group suggested that the PCB-169-mediated toxic effects on the bone might be reduced by a nonplanar PCB-155 congener. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1135-1146, 2017.

Low-dose developmental exposure to bisphenol A alters the femoral bone geometry in wistar rats

BACKGROUND

Bisphenol A (BPA) is a chemical produced in large volumes for use in manufacturing of consumer products and industrial applications, and an endocrine disruptor known to affect several hormonal systems. Bone produces hormones and is additionally a sensitive hormone target tissue, and is thus potentially sensitive to low doses of endocrine disruptors such as BPA, especially during development.

METHODS

110 pregnant Wistar rats were gavaged with 0; 25 μg; 250 μg; 5000 μg or 50,000 μg BPA/kg bodyweight (bw)/day from gestational day 7 until weaning at postnatal day 22. The three-month-old offspring were sacrificed and right femurs collected for length measurements, geometrical measurements by peripheral quantitative computed tomography (pQCT), as well as for analyses of biomechanical properties using the three-point-bending method.

RESULTS

The femur was elongated in female offspring of dams exposed to 25 or 5000 μg BPA/kg bw/day (1.8% and 2.1%, respectively), and increased cortical thickness (4.7%) was observed in male offspring of dams exposed to 25 μg BPA/kg bw/day, compared to controls (p < 0.005). The biomechanical properties of the bone were not significantly altered.

CONCLUSIONS

In utero and lactational exposure to the lowest BPA dose used in this study altered femoral geometry in both male and female offspring. This was observed at 25 μg BPA/kg bw/day, a dose lower than the Human Equivalent Dose (HED) applied by EFSA to set a temporary TDI (609 μg BPA/kg bw/day), and far lower than the No-Observed-Adverse-Effect-Level (NOAEL) (5000 μg BPA/kg bw/day) on which the US FDA TDI is based.

Persistent organic pollutants and inorganic elements in the Balearic shearwater Puffinus mauretanicus wintering off Portugal

This study presents the first data on trace element and organic pollutant concentrations in the Critically Endangered Balearic shearwater Puffinus mauretanicus collected in 2010 and 2011 in Portugal. Trace element levels were below the threshold levels for adverse effects on birds, despite the Hg concentrations in feathers (4.35μg·g-1ww). No significant differences were detected between individuals from 2010 and 2011 except for Se concentrations in liver, feathers and muscle (higher in 2010) and Ag in liver and muscle (higher in 2011). No significant differences were detected in total concentrations of organochlorine compounds in Balearic shearwaters between years, although PCB congeners -101 and -180 presented higher concentrations in individuals from 2010. The PCB congeners -138, -153 and -180, and 4.4-DDE were detected in all individuals. This study on toxic elements and organic pollutants in wintering Balearic shearwaters provides baseline data from which deviations can be detected in the future.

Is the bone tissue of ring-billed gulls breeding in a pollution hotspot in the St. Lawrence River, Canada, impacted by halogenated flame retardant exposure?

Bone metabolism is a tightly regulated process that controls bone remodeling and repair in addition to maintaining circulating calcium and phosphate levels. It has been shown that certain organohalogen contaminants may adversely impact bone tissue metabolism and structure in wildlife species. However, exceedingly few studies have addressed the bone-related effects of organohalogen exposure in birds. The objective of the present study was to investigate the associations between markers of bone metabolism and structural integrity, and concentrations of established and current-use halogenated flame retardants (FRs) in ring-billed gulls (Larus delawarensis) nesting in a known FR hotspot area in the St. Lawrence River (Montreal, Canada). Bone metabolism was assessed using plasma calcium and inorganic phosphate levels, and alkaline phophatase activity, while bone (tarsus; trabecular and cortical sections) structure quality was examined using the percentage of bone tissue comprised in the total bone volume (Bv/Tv) and bone mineral density (BMD). Bv/Tv and BMD of the tarsus tended (not significant) to be positively associated with circulating calcium levels in male ring-billed gulls. Moreover, concentrations of FRs in male bird liver (brominated diphenyl ether (BDE)-154, -183, -201, and -209) and plasma (BDE-209) were negatively correlated with trabecular and cortical BMD of the tarsus. These correlative associations may suggest light demineralization of bone tissue associated with FR exposure in male ring-billed gulls. Present findings provide some evidence that bone (tarsus) metabolism and mineral composition may be impacted in high FR-exposed (mainly to PBDEs) ring-billed gulls breeding in the highly urbanized Montreal region.

Perinatal exposure to environmental contaminants detected in Canadian Arctic human populations changes bone geometry and biomechanical properties in rat offspring

Arctic inhabitants consume large proportions of fish and marine mammals, and are therefore continuously exposed to levels of environmental toxicants, which may produce adverse health effects. Fetuses and newborns are the most vulnerable groups. The aim of this study was to evaluate changes in bone geometry, mineral density, and biomechanical properties during development following perinatal exposure to a mixture of environmental contaminants corresponding to maternal blood levels in Canadian Arctic human populations. Sprague-Dawley rat dams were dosed with a Northern Contaminant Mixture (NCM) from gestational day 1 to postnatal day (PND) 23. NCM contains 27 contaminants comprising polychlorinated biphenyls, organochlorine pesticides, and methylmercury. Femurs were collected on PND 35, 77 and 350, and diaphysis was analyzed by peripheral quantitative computed tomography and three-point bending test, while femoral neck was assessed in an axial loading experiment. Dose-response modeling was performed to establish the benchmark dose (BMD) for the analyzed bone parameters. Exposure to the high dose of NMC resulted in short and thin femur with reduced mechanical strength in offspring at PND35. BMD of femur length, cortical area, and stiffness were 3.2, 1.6, and 0.8 mg/kg bw/d, respectively. At PND77 femur was still thin, but at PND350 no treatment-related bone differences were detected. This study provides new insights on environmental contaminants present in the maternal blood of Canadian Arctic populations, showing that perinatal exposure induces bone alterations in the young offspring. These findings could be significant from a health risk assessment point of view.

Pregnant ewes exposed to multiple endocrine disrupting pollutants through sewage sludge-fertilized pasture show an anti-estrogenic effect in their trabecular bone

Pregnant ewes were maintained on pastures fertilized, twice yearly, with either sewage sludge (2.25tonnes dry matter/ha; Treated; T) or inorganic fertilizer containing equivalent amounts of nitrogen (Control; C), to determine effects on maternal and fetal bone structures, density and mechanical properties of exposure to environmental concentrations of multiple endocrine disrupting compounds (EDCs) and heavy metal pollutants. The ewes were maintained on the respective pastures from the age of about 8months until they were 4-6years of age and they were slaughtered at 110d gestation. Metaphyseal parts of adult ewe femurs exhibited a significantly reduced mean, total cross sectional area (CSA, -4%; p<0.05), lower trabecular bone mineral content (BMC, mg/mm; -18%; p<0.05), trabecular bone mineral density (BMD, mg/cm(3), -8.0%; p<0.05) and trabecular CSA, mm(2), -11.1%; p<0.05) in T compared with C animals. Femurs of T ewes were stronger than those of C ewes but this may reflect greater body weights. At the mid-diaphyseal part of the fetal bones, there was a reduction in endosteal circumference (-6.7%, p<0.05) and marrow cavity area (-13.8%, p<0.05) in the female T fetuses compared with female C fetuses. In the male fetuses the mid-diaphyseal part total bone mineral content was higher (+3.0%, p<0.05) in T than in C animals. No treatment difference in biomechanical bending was detected in the fetuses. It is concluded that ewes grazing pasture fertilized with sewage sludge exhibited an anti-estrogenic effect on their trabecular bone in the form of reduced mineral content and density, despite increased body weight. It is suggested that human exposure to low levels of multiple EDCs may have implications for bone structure and human health.

Anthropogenic pollutants: a threat to ecosystem sustainability?

Pollutants, including synthetic organic materials and heavy metals, are known to adversely affect physiological systems in all animal species studied to date. While many individual chemicals can perturb normal functions, the combined actions of multiple pollutants are of particular concern because they can exert effects even when each individual chemical is present at concentrations too low to be individually effective. The biological effects of pollutants differ greatly between species reflecting differences in the pattern of exposure, routes of uptake, metabolism following uptake, rates of accumulation and sensitivity of the target organs. Thus, understanding of the effects of pollutants on wildlife and ecosystems will require detailed study of many different species, representing a wide range of taxa. However, such studies can be informed by knowledge obtained in more controlled conditions which may indicate likely mechanisms of action and suitable endpoint measurements. Responses may be exacerbated by interactions between the effects of pollutants and environmental stressors, such as under-nutrition or osmotic stresses and so changes in such variables associated with climatic changes may exacerbate physiological responses to pollutant burdens.

Seabirds as indicators of aquatic ecosystem conditions: a case for gathering multiple proxies of seabird health

The use of seabirds as sentinels of the condition of aquatic ecosystems has been well-established. Large environmental perturbations to aquatic food webs (e.g., chemical contamination, overfishing, particulate pollution) have all been detected or monitored by tracking seabirds at colonies. However, seabirds may elicit more subtle, sublethal responses that can also be used to track ecosystem health, or the health of seabird populations. In this article, we advocate for field researchers to plan a priori to collect a broader suite of samples when handling seabirds, and to reach out for collaboration with specialists (e.g., parasitologists, wildlife veterinarians). Collectively, such efforts will greatly improve our ability to establish baseline physiological and chemical levels for seabirds, against which we can detect future changes in aquatic ecosystems.

Fluctuating wing asymmetry and hepatic concentrations of persistent organic pollutants are associated in European shag (Phalacrocorax aristotelis) chicks

In aquatic birds, high body burdens of persistent organic pollutants (POPs) have been associated with developmental effects related to growth, increased fluctuating wing asymmetry, and disruption of the thyroid hormone, vitamin A (retinol) and vitamin E (tocopherol) homeostasis. The aim of the present study was to examine if morphological variables (body mass, liver mass, wing length, tarsus length and head length), fluctuating asymmetry of the wings and tarsus, growth rates and endocrine variables (thyroid hormones, retinol and tocopherol) were associated with hepatic levels of POPs (PCBs, OCPs and PBDEs) in 21 day old chicks of European shag (Phalacrocorax aristotelis). Partial Least Squares (PLS) analysis showed that fluctuating asymmetry of wing bone length (FA(WBL)) was affected by PCB-105, -118, -138, -153, and -180 (r(2)x=0.88, r(2)y=0.35, q(2)=0.29). Bivariate correlation confirmed significant positive relationships between FA(WBL) and each of these PCB congeners. In the PLS model no other biological variables were significantly affected by any of the POPs. Levels of POPs were much lower in the shag chicks than in eggs and in hatchlings from the same breeding colony, most likely due to growth dilution of the compounds. We suggest that the effects of the PCBs on FA(WBL) may be due to effects of these compounds on bone growth and bone structure. FA(WBL) may have functional effects on the fitness if it persists after fledging.

Exposure to pastures fertilised with sewage sludge disrupts bone tissue homeostasis in sheep

The femurs of male and female sheep (Ovis aries), aged 18 months, bred on pastures fertilized twice annually with sewage sludge (2.25 tonnes dry matter/ha; Treated; T)) or on pastures treated with inorganic fertilizer (Control; C) were studied, using peripheral Quantitative Computed Tomography (pQCT) and the three-point bending test. Males were maintained on the respective treatments from conception to weaning and then maintained on control pastures while the females were maintained on the respective treatments until slaughter. T rams exhibited increased total bone mineral density (BMD) at the metaphyseal part of femur (+10.5%, p<0.01) compared with C rams but had a reduced total cross sectional area (CSA, -11.5%, p<0.001), trabecular CSA (-17.1%, p<0.01) and periosteal circumference (-5.7%, p<0.001). In the mid-diaphyseal part, T rams had an increased total BMD (+13.8%, p<0.0001) and stiffness (+6.4%, p<0.01) but reduced total CSA (-12.1%, p<0.0001) and marrow cavity (-25.8%, p<0.0001), relative to C rams. In ewes although pQCT analysis of neither the metaphyseal nor the mid-diaphyseal part of the female femur bones showed any significant differences with treatment, the biomechanical method revealed a reduction in load at failure (-17.3%, p<0.01) and stiffness (-10.7%, p<0.05) amongst T ewes. It is concluded that exposure to pollutants present in sewage sludge can perturb bone tissue homeostasis in sheep, but particularly in males.