The use of a complex tetra-culture alveolar model to study the biological effects induced by gold nanoparticles with different physicochemical properties.

A substantial increase in engineered nanoparticles in consumer products has been observed, heightening human and environmental exposure. Inhalation represents the primary route of human exposure, necessitating a focus on lung toxicity studies. However, to avoid ethical concerns the use of in vitro models is an efficient alternative to in vivo models. This study utilized an in vitro human alveolar barrier model at air-liquid-interface with four cell lines, for evaluating the biological effects of different gold nanoparticles. Exposure to PEGylated gold nanospheres, nanorods, and nanostars did not significantly impact viability after 24 h, yet all AuNPs induced cytotoxicity in the form of membrane integrity impairment. Gold quantification revealed cellular uptake and transport. Transcriptomic analysis identified gene expression changes, particularly related to the enhancement of immune cells. Despite limited impact, distinct effects were observed, emphasizing the influence of nanoparticles physicochemical parameters while demonstrating the model's efficacy in investigating particle biological effects.

Microplastics from miscellaneous plastic wastes: Physico-chemical characterization and impact on fish and amphibian development.

Microplastic pollution represents a global problem with negative impacts on aquatic environment and organisms' health. To date, most of the laboratory toxicological studies on microplastics (MPs) have made use of single commercial micro and nano-polymers, which do not reflect the heterogeneity of environmental MPs. To improve the relevance of the hazard assessment, micrometer-sized plastic particles of miscellaneous non-reusable waste plastics, with size <100 µm and <50 µm (waste microplastics, wMPs), were characterized by microscopic and spectroscopic techniques and tested on developing zebrafish and Xenopus laevis by FET and FETAX assays respectively. Moreover, the modalities of wMP interaction with the embryonic structures, as well as the histological lesions, were explored by light and electron microscopy. We have shown that wMPs had very heterogeneous shapes and sizes, were mainly composed of polyethylene and polypropylene and contained metal and organic impurities, as well as submicrometric particle fractions, features that resemble those of environmental occurring MPs. wMPs (0.1-100 mg/L) caused low rate of mortality and altered phenotypes in embryos, but established species-specific biointeractions. In zebrafish, wMPs by adhering to chorion were able to delay hatching in a size and concentration dependent manner. In Xenopus embryos, which open stomodeum earlier than zebrafish, wMPs were accumulated in intestinal tract, where produced mechanical stress and stimulated mucus overproduction, attesting an irritation response. Although wMP biointeractions did not interfere with morphogenesis processes, further studies are needed to understand the underlying mechanisms and long-term impact of these, or even smaller, wMPs.

Biological effects of combustion-derived particles from different biomass sources on human bronchial epithelial cells.

Combustion-derived particles (CDPs), in particular from traffic, are regarded as a central contributor for adverse health effects linked to air pollution. Recently, also biomass burning has been recognized as an important source for CDPs. Here, the effects of CDPs (PM10) originating from burning of pellet, charcoal and wood on key processes associated to lung carcinogenesis were explored. Human bronchial epithelial cells (HBEC3-KT) were exposed to 2.5 µg/cm2 of CDPs for 24 h and biological effects were examined in terms of cytotoxicity, inflammation, epithelial to mesenchymal transition (EMT)-related effects, DNA damage and genotoxicity. Reduced cell migration, inflammation and modulation of various PM-associated genes were observed mainly after exposure to wood and pellet. In contrast, only particles from pellet burning induced alteration in cell proliferation and DNA damage, which resulted in cell cycle alterations. Charcoal instead, appeared in general less effective in inducing pro-carcinogenic effects. These results illustrate differences in the toxicological profile due to the CDPs source. The different chemical compounds adsorbed on CDPs seemed to be central for particle properties, leading to an activation of various cellular signaling pathways involved in early steps of cancer progression.

Combustion-derived particles from biomass sources differently promote epithelial-to-mesenchymal transition on A549 cells.

Combustion-derived particles (CDPs), due to the presence in their composition of several toxic and carcinogenic chemical compounds, such as polycyclic aromatic hydrocarbons (PAHs) and metals, are linked to several respiratory diseases, including lung cancer. Epithelial-to-mesenchymal transition (EMT) is a crucial step in lung cancer progression, involving several morphological and phenotypical changes. The study aims to investigate how exposure to CDPs from different biomass sources might be involved in cancer development, focusing mainly on the effects linked to EMT and invasion on human A549 lung cells. Biomass combustion-derived particles (BCDPs) were collected from a stove fuelled with pellet, charcoal or wood, respectively. A time course and dose response evaluation on cell viability and pro-inflammatory response was performed to select the optimal conditions for EMT-related studies. A significant release of IL-8 was found after 72 h of exposure to 2.5 µg/cm2 BCDPs. The EMT activation was then examined by evaluating the expression of some typical markers, such as E-cadherin and N-cadherin, and the possible enhanced migration and invasiveness. Sub-acute exposure revealed that BCDPs differentially modulated cell viability, migration and invasion, as well as the expression of proteins linked to EMT. Results showed a reduction in the epithelial marker E-cadherin and a parallel increase in the mesenchymal markers N-cadherin, mainly after exposure to charcoal and wood. Migration and invasion were also increased. In conclusion, our results suggest that BCDPs with a higher content of organic compounds (e.g. PAHs) in their chemical composition might play a crucial role in inducing pro-carcinogenic effects on epithelial cells.

Exposure during embryonic development to Roundup® Power 2.0 affects lateralization, level of activity and growth, but not defensive behaviour of marsh frog tadpoles.

As glyphosate-based herbicides, sold under the commercial name Roundup®, represent the most used herbicides in the world, contamination of the freshwater environment by glyphosate has become a widespread issue. In Italy, glyphosate was detected in half of the surface waters monitoring sites and its concentrations were higher than environmental quality standards in 24.5% of them. It can last from days to months in water, leading to exposure for aquatic organisms and specifically to amphibians' larvae that develop in shallow water bodies with proven effects to development and behaviour. In this study, we tested the effects of a 96 h exposure during embryonic development of marsh frog's tadpoles to three ecologically relevant Roundup® Power 2.0 concentrations. As expected, given the low concentrations tested, no mortality was observed. Morphological measurements highlighted a reduction in the total length in tadpoles exposed to 7.6 mg a.e./L, while an increase was observed at lower concentrations of 0.7 and 3.1 mg a.e./L compared to control group. Tadpoles raised in 7.6 mg a.e./L also showed a smaller tail membrane than those raised in the control solution. Regarding behaviour, we tested tadpoles in two different sessions (Gosner stages 25 and 28/29) for lateralization, antipredator response and basal activity. Lower intensity of lateralization was detected in tadpoles raised at the highest Roundup® concentration in the first session of observation, while no significant difference among treatments was observed in the second one. In both sessions, effects of Roundup® Power 2.0 embryonic exposure on antipredator response, measured as the proportional change in activity after the injection of tadpole-fed predator (Anax imperator) cue, were not detected. Tadpoles exposed during embryonic development to Roundup® exhibited lower basal activity than the control group, with the strongest reduction for the 7.6 mg a.e./L treatment. Our results reinforce the concern of Roundup® contamination impact on amphibians.

Recovery ability of human adipose stem cells exposed to cobalt nanoparticles: outcome of dissolution.

Aim: To demonstrate that cobalt nanoparticles doses are safe for use in humans and to understand the consequences of the particulate effects, which may persist inside the cells. Materials & methods: Human adipose stem cells were used. We evaluated cell recovery by viability test, morphology and ultrastructure using electronic and optical microscopy, while gene expression was assessed utilizing real-time PCR. Results: After exposure, most stem cells recovered their normal function. Co3O4-nanoparticles remained inside the cell for the entirety of the considered time. A slight modification of gene expression was observed in the exposed cells. Conclusion: After exposure to 100 M cobalt nanoparticles, most cells returned to normal function. Nanoparticle toxicity was due to ions released by dissolution as well as from the nanoparticles themselves.

Iron nanoparticle bio-interactions evaluated in Xenopus laevis embryos, a model for studying the safety of ingested nanoparticles.

Iron nanoparticles (NPs) have been proposed as a tool in very different fields such as environmental remediation and biomedical applications, including food fortification against iron deficiency, even if there is still concern about their safety. Here, we propose Xenopus laevis embryos as a suitable model to investigate the toxicity and the bio-interactions at the intestinal barrier of Fe3O4 and zerovalent iron (ZVI) NPs compared to Fe(II) and (III) salts in the 5 to 100 mg Fe/L concentration range using the Frog Embryo Teratogenesis Assay in Xenopus (FETAX). Our results demonstrated that, at concentrations at which iron salts induce adverse effects, both iron NPs do not cause acute toxicity or teratogenicity even if they accumulate massively in the embryo gut. Prussian blue staining, confocal and electron microscopy allowed mapping of iron NPs in enterocytes, along the paracellular spaces and at the level of the basement membrane of a well-preserved intestinal epithelium. Furthermore, the high bioaccumulation factor and the increase in embryo length after exposure to iron NPs suggest greater iron intake, an essential element for organisms. Together, these results improve the knowledge on the safety of orally ingested iron NPs and their interaction with the intestinal barrier, useful for defining the potential risks associated with their use in food/feed fortification.

Seasonal Variation in the Biological Effects of PM2.5 from Greater Cairo.

Greater Cairo (Egypt) is a megalopolis where the studies of the air pollution events are of extremely high relevance, for the geographical-climatological aspects, the anthropogenic emissions and the health impact. While preliminary studies on the particulate matter (PM) chemical composition in Greater Cairo have been performed, no data are yet available on the PM's toxicity. In this work, the in vitro toxicity of the fine PM (PM2.5) sampled in an urban area of Greater Cairo during 2017-2018 was studied. The PM2.5 samples collected during spring, summer, autumn and winter were preliminary characterized to determine the concentrations of ionic species, elements and organic PM (Polycyclic Aromatic Hydrocarbons, PAHs). After particle extraction from filters, the cytotoxic and pro-inflammatory effects were evaluated in human lung A549 cells. The results showed that particles collected during the colder seasons mainly induced the xenobiotic metabolizing system and the consequent antioxidant and pro-inflammatory cytokine release responses. Biological events positively correlated to PAHs and metals representative of a combustion-derived pollution. PM2.5 from the warmer seasons displayed a direct effect on cell cycle progression, suggesting possible genotoxic effects. In conclusion, a correlation between the biological effects and PM2.5 physico-chemical properties in the area of study might be useful for planning future strategies aiming to improve air quality and lower health hazards.

In vitro lung toxicity of indoor PM10 from a stove fueled with different biomasses.

Biomass combustion significantly contributes to indoor and outdoor air pollution and to the adverse health effects observed in the exposed populations. Besides, the contribution to toxicity of the particles derived from combustion of different biomass sources (pellet, wood, charcoal), as well as their biological mode of action, are still poorly understood. In the present study, we investigate the toxicological properties of PM10 particles emitted indoor from a stove fueled with different biomasses. PM10 was sampled by gravimetric methods and particles were chemically analyzed for Polycyclic Aromatic Hydrocarbons (PAHs) and elemental content. Human lung A549 cells were exposed for 24 h to 1-10 µg/cm2 PM and different biological endpoints were evaluated to comparatively estimate the cytotoxic, genotoxic and pro-inflammatory effects of the different PMs. Pellet PM decreased cell viability, inducing necrosis, while charcoal and wood ones mainly induced apoptosis. Oxidative stress-related response and cytochrome P450 enzymes activation were observed after exposure to all the biomasses tested. Furthermore, after pellet exposure, DNA lesions and cell cycle arrest were also observed. The severe genotoxic and pro-necrotic effects observed after pellet exposure were likely the consequence of the high metal content. By administering the chelating agent TPEN, the genotoxic effects were indeed rescued. The higher content in PAHs measured in wood and charcoal PMs was likely the reason of the enhanced expression of metabolizing and oxidative stress-related enzymes, like CYP1B1 and HO-1, and the consequent increase in apoptotic cell death. These data suggest that combustion particles from different biomass sources may impact on lung cells according to different pathways, finally producing different toxicities. This is strictly related to the PM chemical composition, which reflects the quality of the combustion and the fuel in particular. Further studies are needed to clarify the role of particle dimension and the molecular mechanisms behind the harmful effects observed.

Teratogenic hazard of BPEI-coated silver nanoparticles to Xenopus laevis.

Silver nanoparticles (AgNPs) are among the most exploited antimicrobial agents and are used in many consumer products. Size and surface reactivity are critical physico-chemical properties responsible for NPs toxicity, and surface coatings, often used to functionalize or stabilize AgNPs, can influence their toxic profile and biocompatibility. In the current study the developmental toxicity of (1) negatively charged citrate-coated AgNPs (Cit-AgNPs), (2) positively charged branched polyethylenimine-coated AgNPs (BPEI-AgNPs), and (3) Ag+ (from 0.0625 to 0.75 mg Ag/L) was investigated by the standard Frog Embryo Teratogenesis Assay - Xenopus (FETAX). In order to identify the most sensitive developmental phase, embryos were also exposed during different embryonic stages. Morphological and bio-physical studies were performed to characterize tissue lesions and NP uptake. The results suggest that Ag+ was strongly embryo-lethal. Contrary to Cit-AgNPs, the positively charged BPEI-AgNPs exert a concentration-dependent effect on lethality and malformations of embryos. The BPEI-AgNPs showed the highest teratogenic index (TI = 1.6), pointing out the role of functional coating in determining the developmental hazard. The highest susceptibility to BPEI-AgNPs was during early embryogenesis, when embryos are still enclosed in the fertilization envelope, and the post-stomodeum opening stages, when NPs ingestion occurs. In BPEI-AgNPs treated larvae, the histological examination revealed irregular intestinal diverticula coupled with edematous connective tissue. Small NPs aggregates are mapped throughout the intestinal mucosa and secondary target organs by two-photon excitation microscopy. We conclude that a teratogenic risk may be associated with BPEI-AgNPs exposure, but the modality of NP-tissue interactions and the teratogenic mechanism need further investigations to be better defined.

Do Nanoparticle Physico-Chemical Properties and Developmental Exposure Window Influence Nano ZnO Embryotoxicity in Xenopus laevis?

The growing global production of zinc oxide nanoparticles (ZnONPs) suggests a realistic increase in the environmental exposure to such a nanomaterial, making the knowledge of its biological reactivity and its safe-by-design synthesis mandatory. In this study, the embryotoxicity of ZnONPs (1-100 mg/L) specifically synthesized for industrial purposes with different sizes, shapes (round, rod) and surface coatings (PEG, PVP) was tested using the frog embryo teratogenesis assay-Xenopus (FETAX) to identify potential target tissues and the most sensitive developmental stages. The ZnONPs did not cause embryolethality, but induced a high incidence of malformations, in particular misfolded gut and abdominal edema. Smaller, round NPs were more effective than the bigger, rod ones, and PEGylation determined a reduction in embryotoxicity. Ingestion appeared to be the most relevant exposure route. Only the embryos exposed from the stomodeum opening showed anatomical and histological lesions to the intestine, mainly referable to a swelling of paracellular spaces among enterocytes. In conclusion, ZnONPs differing in shape and surface coating displayed similar toxicity in X. laevis embryos and shared the same target organ. Nevertheless, we cannot exclude that the physico-chemical characteristics may influence the severity of such effects. Further research efforts are mandatory to ensure the synthesis of safer nano-ZnO-containing products.

Palmitoylethanolamide relieves pain and preserves pancreatic islet cells in a murine model of diabetes.

We previously demonstrated that the intraperitoneal administration of palmitoylethanolamide (PEA) in mice with chronic constriction injury of the sciatic nerve evoked a relief of both thermal hyperalgesia and mechanical allodynia in neuropathic mice. Since diabetic neuropathy is one of the most common long-term complications of diabetes, we explored the ability of PEA to also relief this kind of chronic pain, employing the well established streptozotocin-induced animal model of type 1 diabetes. Our findings demonstrated that PEA relieves mechanical allodynia, counteracts nerve growth factor deficit, improves insulin level, preserves Langerhans islet morphology reducing the development of insulitis in diabetic mice. These results suggest that PEA could be effective in type 1-diabetic patients not only as pain reliever but also in controlling the development of pathology.

Toxicity Evaluation of a New Zn-Doped CuO Nanocomposite With Highly Effective Antibacterial Properties.

The increased resistances to conventional antibiotics determine a strong need for new antibacterials, and specific syntheses at the nanoscale promise to be helpful in this field. A novel Zinc-doped Copper oxide nanocomposite (nZn-CuO) has been recently sonochemically synthesized and successfully tested also against multi-drug resistant bacteria. After synthesis and characterization of the physicochemical properties, the new nZn-CuO is here evaluated by the Frog Embyo Teratogenesis Assay-Xenopus test for its toxicological potential and this compared with that of nCuO and nZnO synthesized under the same conditions. No lethal effects are observed, while malformations and growth retardation slightly increase after nZn-CuO exposure. Nevertheless, these effects are smaller than those of nZnO. NP uptake by embryo tissues increase significantly with increasing NP concentrations, while no significant accumulation and adverse effects are seen after exposure to soluble Cu(2+) and Zn(2+) at the concentrations dissolved from the NPs. Key oxidative response genes are upregulated by nZn-CuO, as well as by nCuO and nZnO, suggesting the common mechanism of action. Considering the enhanced biocidal activity shown by the nanocomposite, together with the results presented in this study, we can affirm that the doping of the metal oxide nanoparticles should be considered a useful tool to engineer a safer nano-antibacterial.

Responsiveness of hepatic and cerebral cytochrome P450 in rat offspring prenatally and lactationally exposed to a reconstituted PCB mixture.

Perinatal polychlorinated biphenyl (PCB) exposures still remain a serious health concern because offspring receive PCB burden from mother during vulnerable processes of development. Since cytochrome P450 (CYP) represents a toxicological endpoint, in the present study, representing an extended investigation of a previous multitasked one, we explored the long-term responsiveness of CYP1A and CYP2B isoforms by Western blot analysis in liver and whole brain of lactating (PN12), weaning (PN21), and adult offspring (PN60) rats prenatally and lactationally exposed to a reconstituted PCB mixture (RM) of noncoplanar PCB138, 153, 180, and coplanar PCB126 congeners. We chose highly chlorinated PCBs instead of lower chlorinated one, because their recalcitrance to biotransformation makes easy their accumulation/persistence in tissues and breast milk. Dioxin-like congener PCB126 binding aryl hydrocarbon receptor (AHR) is responsible of many toxic effects. Pregnant Sprague-Dawley dams with high affinity AHR received subcutaneous injection of RM (10 mg/kg body weight) daily during gestation (days 15-19) and twice a week during breast-feeding. The results evidenced a transfer of PCBs to neonates through milk and a significant responsiveness of hepatic CYP in both mothers and offspring. In liver of exposed progeny, CYP isoforms exhibited a significant increment at PN12 (70% over control) and at PN21 (270% over control). Contrary to dams, in adult PCB offspring CYP levels showed a decline up to values similar to those of control. This transient developmental responsiveness of CYP isoforms in offspring liver reflects roughly the time course of hepatic PCB levels previously reported. Even if congeners were detected in brain, we failed in evidencing a responsiveness of CYP isoforms probably because of region-specific CYP expression in this organ. In conclusion, induction of offspring hepatic CYP is index of liver PCB burden, and despite the insensitivity of whole brain CYP we cannot exclude brain vulnerability toward PCB. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 856-866, 2014.

Non-neuronal cell modulation relieves neuropathic pain: efficacy of the endogenous lipid palmitoylethanolamide.

We have previously shown that the endogenous lipid palmitoylethanolamide (PEA) induced relief of neuropathic pain through an action upon receptors located on the nociceptive pathway. Recently, it has been proposed that immune cells, in particular mast cells, and microglia, by releasing algogen mediators interact with neurons to alter pain sensitivity thereby contributing to the development and maintenance of chronic pain states. The aim of this work was to explore whether the anti-nociceptive properties of PEA might be accompanied by modulation of these non-neuronal cells. Mice were subjected to a chronic constriction injury model of neuropathic pain and treated with PEA. The data show that at the earlier (3 days) time-point after nerve injury there was a substantial recruitment of mast cells whose activation was not yet pronounced. In contrast, at the later time point (8 days) there was no further increase in mast cell number, but rather a marked activation of these cells. An up-regulation of activated microglia was found in the spinal cord of neuropathic pain mice. PEA delayed mast cell recruitment, protected mast cells against degranulation and abolished the nerve growth factor increase in sciatic nerve concomitantly preserving the nerve from degeneration, while reducing microglia activation in the spinal cord. These findings support the idea that non-neuronal cells may be a valuable pharmacological target to treat neuropathic pain since the current neuronal-direct drugs are still unsatisfactory. In this context PEA could represent an innovative molecule, combining a dual analgesic activity, both on neurons and on nonneuronal cells.

Rimonabant, a cannabinoid CB1 receptor antagonist, attenuates mechanical allodynia and counteracts oxidative stress and nerve growth factor deficit in diabetic mice.

Diabetes is one of the leading causes of painful neuropathy and to date, besides a tight glycemic control, a viable treatment for this complication is not available. Rimonabant is a selective cannabinoid CB(1) receptor antagonist that produces a significant increase in insulin sensitivity and a reduction of HbA(1c) in diabetic patients. This study aimed to investigate the therapeutic potential of rimonabant in relieving diabetes-induced neuropathic pain. The repeated treatment with rimonabant evoked a significant attenuation of mechanical allodynia in diabetic mice that was dose- and time-dependent. This effect occurred without alteration of hyperglycemia, but it was associated with significant effects on many key players in the pathogenesis of diabetic neuropathy. Metabolic changes induced by hyperglycemia lead to oxidative stress, deregulation of cytokine control and reduced production and transport of nerve growth factor (NGF), and all these factors contribute to neuropathic pain. Rimonabant treatment reduced oxidative stress in peripheral nerve, as revealed by the ability of the compound to counteract the reduced glutathione (GSH) depletion. The same repeated treatment inhibited tumor necrosis factor (TNFalpha) overproduction in the spinal cord and increased the NGF support. This rimonabant-induced improvement might favour the nerve regeneration; accordingly, the histological analysis of sciatic nerves showed a marked degeneration of myelinated fibers in diabetic mice, that was substantially reduced after rimonabant administration. These findings support the hypothesis that CB(1) antagonists would represent a new opportunity for diabetic patients, since currently there are no treatments for painful diabetic neuropathy other than treating the diabetic condition per se.

Effects of TCDD on spermatogenesis related factor-2 (SRF-2): gene expression in Xenopus.

2,3,7,8-Tetra-chlorodibenzo-p-dioxin (TCDD) is one of the most toxic dioxins belonging to the wide family of Endocrine Disruptors (EDs), environmental chemicals that adversely interfere with endocrine processes and upset normal function of some target systems. It has been hypothesized that EDs enter cellular cytosol, bind to the Aryl Hydrocarbon Receptor (AhR) and form a heterodimer with the AhR nuclear translocator; this complex binds xenobiotic responsive elements that drive activation of the so-called "Ah gene battery". Spermatogenesis Related Factor-2 (SRF-2) is one of the most recently cloned genes involved in germ cell division and differentiation, whose expression seems to be affected by treatment with TCDD. With the aim to try to clarify the underlying mechanism of TCDD and to investigate if SRF-2 gene represents a good biomarker for ED exposure, we used Xenopus laevis as an animal model, considered to be almost insensitive toward TCDD effects. In this study we reported the partial cloning of SRF-2 cDNA in X. laevis; we then evaluated the SRF-2 expression in embryos exposed to TCDD 0.62 microM by real-time PCR. We also analyzed SRF-2 expression in several adult control tissues and in testis after perilymphatic injection of a single dose of 10 microg/kg body weight. Although SRF-2 expression does not seem to be affected by the treatment, exposed embryos died within 15 days. In the light of these results, we can conclude that SRF-2 is not a good candidate in signalling EDs exposure and that the molecular mechanism for TCDD toxicity in Xenopus likely involves the AhR signalling cascade, as in other vertebrate species.

The effects of accumulation of an environmentally relevant polychlorinated biphenyl mixture on cytochrome P450 and P-glycoprotein expressions in fetuses and pregnant rats.

The aim of this study was to improve knowledge about transplacental transfer of an environmentally relevant PCB mixture by evaluating congener levels in livers and brains of rat dams and fetuses after maternal exposure, and correlating them to the levels of CYP450 and P-glycoprotein, involved in biotransformation and xenobiotics export, respectively. Pregnant dams were injected daily from gestation day (GD) 15 to 19 with 10mgkg(-1) of a reconstituted mixture (RM) composed of PCB138, 153, 180 and 126. Our data indicate that at GD20 RM is partitioned among maternal tissues, and that fetuses are not excluded from this distribution, evidencing a placental transfer of PCBs. Considering the ratio of maternal and fetal PCB concentrations based on lipid-weight, the amounts of congeners were 7-fold lower in fetal livers than in maternal livers and 25-30-fold higher in fetal brains than in maternal ones. Moreover, in dams the congeners were able to induce hepatic CYP450 response (total CYP450, CYP1A and CYP2B), but failed to increase P-170 expression, while in fetuses the constitutive expression of CYP450 and P-170 was not induced by treatment. Pearson Product-Moment Correlation applied to treated group data suggests that PCB accumulation in fetal livers, but not in brains, depended principally on their mothers' intoxication pattern. On the whole, these results emphasize the maternal liver and the fetal brain as depot organs for PCB sequestration and their susceptibility towards PCB toxicological risk. Moreover they highlight the lack of a coordinated response between the investigated defence mechanism.

Chronic treatment with polychlorinated biphenyls (PCB) during pregnancy and lactation in the rat: Part 1: Effects on somatic growth, growth hormone-axis activity and bone mass in the offspring.

Polychlorinated biphenyls (PCBs) are pollutants detected in animal tissues and breast milk. The experiments described in the present paper were aimed at evaluating whether the four PCB congeners most abundant in animal tissues (PCB-138, -153, -180 and -126), administered since fetal life till weaning, can induce long-term alterations of GH-axis activity and bone mass in the adult rat. We measured PCB accumulation in rat brain and liver, somatic growth, pituitary GH expression and plasma hormone concentrations at different ages. Finally, we studied hypothalamic somatostatin expression and bone structure in adulthood, following long-term PCB exposure. Dams were treated during pregnancy from GD15 to GD19 and during breast-feeding. A constant reduction of the growth rate in both male and female offspring from weaning to adulthood was observed in exposed animals. Long-lasting alterations on hypothalamic-pituitary GH axis were indeed observed in PCB-exposed rats in adulthood: increased somatostatin expression in hypothalamic periventricular nucleus (both males and females) and lateral arcuate nucleus (males, only) and decreased GH mRNA levels in the pituitary of male rats. Plasma IGF-1 levels were higher in PCB-exposed male and female animals as compared with controls at weaning and tended to be higher at PN60. Plasma testosterone and thyroid hormone concentrations were not significantly affected by exposure to PCBs. In adulthood, PCBs caused a significant reduction of bone mineral content and cortical bone thickness of tibiae in male rat joint to increased width of the epiphyseal cartilage disk. In conclusion, the developmental exposure to the four selected PCB compounds used in the present study induced far-reaching effects in the adult offspring, the male rats appearing more sensitive than females.

Exposure to the organophosphorus pesticide chlorpyrifos inhibits acetylcholinesterase activity and affects muscular integrity in Xenopus laevis larvae.

The effect of organophosphate pesticide chlorpyrifos (CPF) on acetylcholinesterase (AChE) activity and on skeletal muscle development in Xenopus laevis larvae was studied. To achieve our purpose embryos were exposed to 100, 250 and 3000 microg/l CPF concentrations from late blastula stage (8 h postfertilization, p.f.) to stage 47 (120 h p.f.) and the appearance of AChE activity was monitored every 24 h. Compared with control, CPF treated larvae showed a dose dependent AChE inhibition during the early stages (beginning from 24 h until 120 h p.f.) that are crucial for neuromuscular development. The amount of AChE activity that can still be measured in treated larvae at stage 47 relative to that of the control, ranged from 28% in CPFs 100 microg/l to 4% in CPFs 3000 microg/l. These low AChE activities were associated with muscular damages such as reduced myotome size and hypertrophies coupled with extensive vacuolated regions in myocytes. The occurrence of this tissue-specific injury was related to CPF concentrations and was most pronounced in CPFs 3000 microg/l which revealed a very severe AChE inhibition during the exposure. Since AChE is the major neurotransmitter of the neuromuscular system, this initial descriptive study will be an useful starting-point to ongoing and future subcellular/molecular studies that correlate the morphological damage with changes in AChE activity.