Long-term Oral Exposure Research Articles

Chronic oral toxicity protocol for adult solitary bees (Osmia bicornis L.): Reduced survival under long-term exposure to a “bee-safe” insecticide

Pollinators are essential for crop productivity. Yet, in agricultural areas, they may be threatened by pesticide exposure. Current pesticide risk assessments predominantly focus on honey bees, with a lack of standardized protocols for solitary bees. This study addresses this gap by developing a long-term oral exposure protocol tailored for O. bicornis. We conducted initial trials to determine optimal container sizes and feeding methods, ensuring high survival rates and accurate syrup consumption measurements. A validation test involving five laboratories was then conducted with the insecticide Flupyradifurone (FPF). Control mortality thresholds were set at ≤ 15% at 10 days. Three laboratories achieved ≤10%, demonstrating the protocol's effectiveness in maintaining healthy test populations. The seasonal timing of experiments influenced control mortality, underscoring the importance of aligning tests with the natural flight period of the population used. Our findings revealed dose-dependent effects of FPF on syrup consumption, showing stimulatory effects at lower concentrations and inhibitory effects at higher ones. The 10-day median lethal daily dose (LDD50) of FPF for O. bicornis (531.92 ng/bee/day) was 3.4-fold lower than that reported for Apis mellifera (1830 ng/bee/day), indicating Osmia's higher susceptibility. Unlike other insecticides, FPF did not exhibit time-reinforced toxicity. This study introduces a robust protocol for chronic pesticide exposure in solitary bees, addressing a critical gap in current risk assessment. Based on its low risk to honey bees and bumblebees, FPF is approved for application during flowering. However, our results suggest that it may threaten Osmia populations under realistic field conditions. Our findings underscore the need for comparative toxicity studies to ensure comprehensive protection of all pollinators and the importance of accounting for long term exposure scenarios in risk assessment. By enhancing our understanding of chronic pesticide effects in solitary bees, our study should contribute to the development of more effective conservation strategies and sustainable agricultural practices.

Bioaccumulation and Male Reproductive Toxicity of the New Brominated Flame Retardant Tetrabromobisphenol A-Bis(2,3-dibromo-2-methylpropyl ether) in Comparison with Hexabromocyclododecane.

Tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) (TBBPA-DBMPE) has come into use as an alternative to hexabromocyclododecane (HBCD), but it is unclear whether TBBPA-DBMPE has less hazard than HBCD. Here, we compared the bioaccumulation and male reproductive toxicity between TBBPA-DBMPE and HBCD in mice following long-term oral exposure after birth. We found that the concentrations of TBBPA-DBMPE in livers significantly increased with time, exhibiting a bioaccumulation potency not substantially different from HBCD. Lactational exposure to 1000 μg/kg/d TBBPA-DBMPE as well as 50 μg/kg/d HBCD inhibited testis development in suckling pups, and extended exposure up to adulthood resulted in significant molecular and cellular alterations in testes, with slighter effects of 50 μg/kg/d TBBPA-DBMPE. When exposure was extended to 8 month age, severe reproductive impairments including reduced sperm count, increased abnormal sperm, and subfertility occurred in all treated animals, although 50 μg/kg/d TBBPA-DBMPE exerted lower effects than 50 μg/kg/d HBCD. Altogether, all data led us to conclude that TBBPA-DBMPE exerted weaker male reproductive toxicity than HBCD at the same doses but exhibited bioaccumulation potential roughly equivalent to HBCD. Our study fills the data gap regarding the bioaccumulation and toxicity of TBBPA-DBMPE and raises concerns about its use as an alternative to HBCD.

The Effects of Short- and Long-Term Ingestion of Plastic Toxin Bisphenol A on Gastrointestinal Transit Time in Rats.

Introduction Exposure to bisphenol A (BPA), a toxic chemical released from plastic, affects various body functions, including reproduction, metabolism, and development. The most common route of exposure to BPA is oral, and the gastrointestinal(GI) tract is, therefore, the first body system to be exposed to BPA. BPA has been well-documented to impair gut contractility in rats, in vitro. It may therefore be hypothesized that BPA may adversely affect GI motility and hence slow down the movement of food, resulting in the increased transit of food bolus in the GI tract. There are no reports so far on the effects of BPA on GI transit time. Objectives The present study was undertaken to examine the impact of exposure to BPA by a single oral dose (termed as short-term ingestion of BPA) and chronic (28-day) oral dose (termed as long-term ingestion of BPA) on the transit time of food bolus in the gut of adult male albino rats. Methods and materials The study was conducted in the Department of Physiology,Institute of MedicalSciences,Banaras Hindu University, Varanasi,Uttar Pradesh, India. In one set of experiments, each animal was fed a food pellet, once (short-term ingestion) containing BPA (2 µg/kg and 50 µg/kg in different groups), and in another set of experiments, each animal was fed a food pellet containing BPA (50 µg/kg/day) for 28 consecutive days (long-term ingestion). Control rats in both sets were fed food pellets without BPA. Subsequently, the gastric transit index (GTI), ileocecal transit index (ICTI), and colonic transit time (CTT) were determined by the standard charcoal marker method. Results One-time ingestion of a food pellet containing BPA caused a significant (p < 0.05) drop in the GTI and ICTI and an increase in the CTT with both doses of BPA (2 and 50 µg/kg). Similarly, after chronic (28-day), oral BPA exposure, a significant decrease in the GTI and ICTT and an increase in CTT were observed. Conclusion Both short-term (one-time) and long-term (28-day) oral exposure to BPA-containing food harmed GI transit. Slow GI transit may lead to metabolic disorders and GI motility disorders, such as constipation.

Biological interactions of polystyrene nanoplastics: Their cytotoxic and immunotoxic effects on the hepatic and enteric systems

As emerging pollutants in the environment, nanoplastics (NPs) can cross biological barriers and be enriched in organisms, posing a greatest threat to the health of livestock and humans. However, the size-dependent toxic effects of NPs in higher mammals remain largely unknown. To determine the size-dependent potential toxicities of NPs, we exposed mouse (AML-12) and human (L02) liver cell lines in vitro, and 6-week-old C57BL/6 mice (well-known preclinical model) in vivo to five different sizes of polystyrene NPs (PS-NPs) (20, 50, 100, 200 and 500 nm). We found that ultra-small NPs (20 nm) induced the highest cytotoxicity in mouse and human liver cell lines, causing oxidative stress and mitochondrial membrane potential loss on AML-12 cells. Unexpectedly in vivo, after long-term oral exposure to PS-NPs (75 mg/kg), medium NPs (200 nm) and large NPs (500 nm) induced significant hepatotoxicity, evidenced by increased oxidative stress, liver dysfunction, and lipid metabolism disorders. Most importantly, medium or large NPs generated local immunotoxic effects via recruiting and activating more numbers of neutrophils and monocytes in the liver or intestine, which potentially resulted in increased proinflammatory cytokine secretion and the tissue damage. The discrepancy in in vitro-in vivo toxic results might be attributed to the different properties of biodistribution and tissue accumulation of different sized NPs in vivo. Our study provides new insights regarding the hepatotoxicity and immunotoxicity of NPs on human and livestock health, warranting us to take immense measures to prevent these NPs-associated health damage.

Long-term and low dose oral malathion exposure causes morphophysiological changes in the colon of rats

BackgroundMalathion (MAL) is an organophosphate insecticide that inhibits cholinesterases, used to control pests in agriculture and to combat mosquitoes that transmit various arboviruses. As acetylcholine is one of the major neurotransmitters of the enteric nervous system (ENS), humans exposed to MAL by ingestion of contaminated food and water can develop symptoms due disfunction of the gastrointestinal tract. Although the deleterious effects after exposure to high doses are recognized, little is known about the long-term and low-dose effects of this pesticide on the structure and motility of the colon. Aimsto evaluate the effects of prolonged oral exposure to low levels of MAL on the wall structure and colonic motility parameters of young rats. Main methodsThe animals were divided into three groups: control, and groups that received 10 or 50 mg/kg of MAL via gavage for 40 days. The colon was collected for histological analysis and analysis of the ENS through the evaluation of total neurons and subpopulations of the myenteric and submucosal plexuses. Cholinesterase activity and functional analyzes of the colon were evaluated. Key findingsMAL treatments (10 and 50 mg/Kg) reduced the butyrylcholinesterase activity, and caused enlargement of faecal pellets, atrophy of muscle layers and several changes in neurons of both myenteric and submucosal plexi. Considering colonic contraction, MAL (50 mg/Kg) increased the number of retrograde colonic migratory motor complexes. SignificanceThe long-term exposure to low doses of MAL affects colonic morphophysiology, which highlights the need to intensify control and care in the use of this pesticide.

Dietary phytoestrogen diosgenin interrupts metabolism, physiology, and reproduction of Swiss albino mice: Possible mode of action as an emerging environmental contaminant, endocrine disruptor and reproductive toxicant.

Dietary phytoestrogens are the main source of environmental contamination due to their estrogen-mimicking and endocrine-disrupting effects, posing a threat to microbial, soil, plant, and animal health. Diosgenin, a phytosteroid saponin, is used in many traditional medicines, nutraceuticals, dietary supplements, contraceptives, and hormone replacement therapies against numerous diseases and disorders. It is important to be aware of the potential risks associated with diosgenin, as well as its potential to cause reproductive and endocrine toxicity. Due to the lack of research on the safety and probable adverse side effects of diosgenin, this work evaluated the endocrine-disrupting and reproductive toxicity of diosgenin in albino mice by following acute toxicity (OECD-423), repeated dose 90-day oral toxicity (OECD-468), and F1 extended one-generation reproductive toxicity (OECD-443) studies. Diosgenin was found to be slightly toxic, with LD50 for male and female mice being 546.26 and 538.72 mg/kg, respectively. Chronic exposure of diosgenin (10, 50, 100, and 200 mg/kg) generated oxidative stress, depleted antioxidant enzymes, disturbed homeostasis of the reproductive hormones, and interrupted steroidogenesis, germ cell apoptosis, gametogenesis, sperm quality, estrous cycle, and reproductive performance in the F0 and F1 offspring. Long-term oral exposure of diosgenin to the mice disturbed the endocrine and reproductive functions and generated transgenerational reproductive toxic effects in F0 and F1 offspring. These results suggest that diosgenin should be used carefully in food products and medical applications due to its potential endocrine-disrupting and reproductive toxic effects. The findings of this study provide a better understanding of the potential adverse effects of diosgenin and the need for appropriate risk assessment and management of its use.

A Roundup herbicide causes high mortality and impairs development of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae)

Glyphosate has and is being used extensively in herbicide formulations worldwide. Thus, glyphosate-based herbicides (GBH) substantially add to the environmental load of pesticides and warrant a strict risk assessment. Ecotoxicological testing of herbicides focuses on non-target plants and higher animals while direct effects on arthropods are only cursory tested on the premise of contact exposure. However, oral exposure, as we show in our case, can be highly relevant for systemic pesticides, such as GBH. Specifically, in crop systems including genetically modified crops that are tolerant to GBH, these herbicides and their breakdown products are present both internally and externally of the crop plants and, therefore, are ingested by the crop-associated arthropod fauna.We tested the effects of oral uptake of the Roundup formulation WeatherMax on larvae of the lacewing Chrysoperla carnea, a model organism in ecotoxicity testing programs. Long-term oral exposure of C. carnea larvae throughout its juvenile life stages was tested with concentrations ranging from 0.001 to 1 % dilution, thus, lower than the 1.67 % recommended for field applications. Inhibition of metamorphosis was observable at 0.1 % but at a concentration of 0.5 %, GBH significantly impaired cocoon formation and led to massive lethal malformations. At GBH concentration of 1 % half of the individuals remained permanent larvae and no adult hatched alive. The effects observed followed a clear dose-response relationship.The hazard caused by direct insecticidal action of GHB after oral uptake is highly relevant for the environmental safety and reveals a gap in regulatory risk assessments that should urgently be addressed, specifically in light of the on-going insect decline.

Long-term daily feeding of cannabidiol is well-tolerated by healthy dogs.

Cannabidiol (CBD) containing dog food and treats are widely commercially available, mirroring the growing popularity of CBD as a supplement for humans. Despite this, experimental evidence of the safety and efficacy of long-term oral exposure in dogs is lacking. The purpose of this study was to address the gap in knowledge around the longer-term suitability and tolerance of a broad-spectrum CBD (THC-free) distillate in clinically healthy dogs. The study was a randomized, placebo-controlled, and blinded study where one group of twenty dogs received daily CBD capsules at a dose of 4 mg/kg of body weight (BW) for a period of 6 months. The control group of twenty dogs received placebo capsules. A comprehensive suite of physiological health measures was performed throughout the study at baseline, and after 2, 4, 10, 18, and 26 weeks of exposure, followed by 4 weeks of washout. CBD concentrations were measured at the same cadence in plasma, feces and urine. Health measures included biochemistry, hematology, urinalysis, in addition to fortnightly veterinary examinations, twice daily well-being observations, and a daily quality-of-life survey. Biochemistry and hematology showed no clinically significant alterations apart from a transient elevation in alkaline phosphatase (ALP) in just over half of the dogs receiving CBD. This elevation was observed in the absence of concurrent elevations of other liver parameters, and without any adverse effects on health and wellbeing. Furthermore, bone alkaline phosphatase (BALP) was simultaneously elevated with a significant, strong (r > 0.9) positive correlation between the two measures, suggesting that the elevation of total ALP was at least partly due to the bone-derived isoform. This study provides evidence that a once-daily oral dose of 4 mg CBD/kg BW is well tolerated in clinically healthy dogs for a duration of 6-months.

Effects of oral exposure to leachate from boiled-water treated plastic products on gut microbiome and metabolomics

By simulating plastic exposure patterns in modern society, the impact of daily exposure to plastic products on mammals was explored. In this study, Institute for Cancer Research (ICR) mice were used to establish drinking water exposure models of three popular kinds of plastic products, including non-woven tea bags, food-grade plastic bags and disposable paper cups. Feces and urine of mice were collected for gut microbiome and metabolomics analysis. Our results showed that the diversity and composition of gut microbiota changed at genus level compared to control group. Lactobacillus, Parabacteroides, Escherichia-shigella and Staphylococcus decreased while Lachnospiraceae increased treated with non-woven tea bags. Escherichia-shigella and Alistipes increased while Parabacteroides decreased treated with food grade plastic bags. Muribaculaceae decreased in the gut microbiota of mice treated with disposable paper cups. Metabolomics has seen changes in the number of metabolites and enrichment of metabolic pathways related to inflammatory responses and immune function. Inflammatory responses were found in histological and biochemical examination. In summary, this study demonstrated that long-term oral exposure to leachate form boiled-water treated plastic products might have effects on gut microbiome and metabolome, which further provided new insights about potential adverse effects for human beings.

Effects of subchronic dietary exposure to the engineered nanomaterials SiO2 and CeO2 in C57BL/6J and 5xFAD Alzheimer model mice

BackgroundThere is an increasing concern about the neurotoxicity of engineered nanomaterials (NMs). To investigate the effects of subchronic oral exposures to SiO2 and CeO2 NMs on Alzheimer’s disease (AD)-like pathology, 5xFAD transgenic mice and their C57BL/6J littermates were fed ad libitum for 3 or 14 weeks with control food pellets, or pellets dosed with these respective NMs at 0.1% or 1% (w/w). Behaviour effects were evaluated by X-maze, string suspension, balance beam and open field tests. Brains were analysed for plaque load, beta-amyloid peptide levels, markers of oxidative stress and neuroinflammation.ResultsNo marked behavioural impairments were observed in the mice exposed to SiO2 or CeO2 and neither treatment resulted in accelerated plaque formation, increased oxidative stress or inflammation. In contrast, the 5xFAD mice exposed to 1% CeO2 for 14 weeks showed significantly lower hippocampal Aβ plaque load and improved locomotor activity compared to the corresponding controls.ConclusionsThe findings from the present study suggest that long-term oral exposure to SiO2 or CeO2 NMs has no neurotoxic and AD-promoting effects. The reduced plaque burden observed in the mice following dietary CeO2 exposure warrants further investigation to establish the underlying mechanism, given the easy applicability of this administration method.

The impact of long-term oral exposure to low doses of acrylamide on the hematological indicators, immune functions, and splenic tissue architecture in rats

There is a global increase in daily dietary intake of acrylamide (ACR) owing to its presence in various foods. However, several toxicological issues are still unclear, particularly after oral exposure to low doses for long durations. As a result, the objective of this research was to investigate the effects of giving male Wistar rats two dosages of ACR (1 or 2 mg/kg b.wt.) via oral gavage once a day for 90 days on blood components, immune markers, and splenic tissue. The results revealed that leukopenia, lymphocytopenia, eosinophilia, and thrombocytopenia were all found to be ACR dose-dependent. In addition, ACR-treated rats had considerably higher IgG and IgM levels. Following ACR exposure, phagocytic activity, lysozyme, and nitric oxide levels were significantly reduced. In ACR-exposed rats, there was a significant reduction in lymphocyte proliferation but an increase in LDH activity. Both splenic tissue and bone marrow showed a variety of degenerative changes. There was a significant increase in CD4+ and CD8+ immunolabeling. Rats exposed to ACR at both levels showed a significant rise in comet variables. Overall, our findings suggested that long-term exposure to ACR could cause hematological disorders, DNA damage, and disturbances of immune functions.

Chronic cannabis smoking-enriched oral pathobiont drives behavioral changes, macrophage infiltration, and increases β-amyloid protein production in the brain.

BackgroundLittle is known about chronic cannabis smoking-associated oral microbiome and its effects on central nervous system (CNS) functions.MethodsIn the current study, we have analyzed the saliva microbiome in individuals who chronically smoked cannabis with cannabis use disorder (n = 16) and in non-smoking controls (n = 27). The saliva microbiome was analyzed using microbial 16S rRNA sequencing. To investigate the function of cannabis use-associated oral microbiome, mice were orally inoculated with live Actinomyces meyeri, Actinomyces odontolyticus, or Neisseria elongata twice per week for six months, which mimicked human conditions.FindingsWe found that cannabis smoking in humans was associated with oral microbial dysbiosis. The most increased oral bacteria were Streptococcus and Actinomyces genus and the most decreased bacteria were Neisseria genus in chronic cannabis smokers compared to those in non-smokers. Among the distinct species bacteria in cannabis smokers, the enrichment of Actinomyces meyeri was inversely associated with the age of first cannabis smoking. Strikingly, oral exposure of Actinomyces meyeri, an oral pathobiont, but not the other two control bacteria, decreased global activity, increased macrophage infiltration, and increased β-amyloid 42 protein production in the mouse brains.InterpretationThis is the first study to reveal that long-term oral cannabis exposure is associated oral enrichment of Actinomyces meyeri and its contributions to CNS abnormalities.

ZnO nanoparticles promote the malignant transformation of colorectal epithelial cells in APCmin/+ mice

As the use of zinc oxide nanoparticles (ZnO NPs) in everyday products grows, so does concern about health risks. However, no findings on the gastrointestinal toxicity of ZnO NPs have been published. We investigated the possible malignant transformation of ZnO NPs in the mice’s colonic tissues using the APCmin/+ mouse model with a premalignant lesion in intestinal epithelial cells. Higher doses and long-term oral exposure to ZnO NPs were found to mildly promote colonic inflammation in WT mice, while they moderately or strongly exacerbated the severity of chronic inflammation and tumorigenesis in APCmin/+ mice with intestinal adenomatous polyposis. The ZnO NPs-induced inflammation and tumorigenesis in colonic epithelial cells was linked to the activation of CXCR2/NF-κB/STAT3/ERK and AKT pathways. Analysis of the ZnO NPs-exacerbated intestinal adenomatous polyposis in APCmin/+ mice revealed that ZnO NPs could activate the APC-driven Wnt/β-catenin signaling pathway, exacerbating intestinal tumorigenesis. In fact, ZnO NPs have been shown to increase intestinal inflammation and tumorigenesis in APCmin/+ mice by releasing free Zn2+. In WT mice, a low dose of ZnO NPs (26 mg/kg/day) did not cause intestinal inflammation. In conclusion, higher doses and prolonged exposure to ZnO NPs promote the malignant transformation of precancerous epithelial cells.

Long-term oral prednisolone exposure in primary care for bullous pemphigoid: population-based study.

BackgroundOral prednisolone is the mainstay treatment for bullous pemphigoid, an autoimmune blistering skin disorder affecting older people. Treatment with moderate-to-high doses is often initiated in secondary care, but then continued in primary care.AimTo describe long-term oral prednisolone prescribing in UK primary care for adults with bullous pemphigoid from 1998 to 2017.Design and settingA prospective cohort study using routinely collected data from the Clinical Practice Research Datalink, a primary care database containing the healthcare records for over 17 million people in the UK.MethodOral prednisolone exposure was characterised in terms of the proportion of individuals with incident bullous pemphigoid prescribed oral prednisolone following their diagnosis, and the duration and dose of prednisolone.ResultsIn total, 2312 (69.6%) of 3322 people with bullous pemphigoid were prescribed oral prednisolone in primary care. The median duration of exposure was 10.6 months (interquartile range [IQR] 3.4–24.0). Of prednisolone users, 71.5% were continuously exposed for >3 months, 39.7% for >1 year, 14.7% for >3 years, 5.0% for >5 years, and 1.7% for >10 years. The median cumulative dose was 2974 mg (IQR 1059–6456). Maximum daily doses were ≥10 mg/day in 74.4% of prednisolone users, ≥20 mg/day in 40.7%, ≥30 mg/day in 18.2%, ≥40 mg/day in 6.6%, ≥50 mg/day in 3.8%, and ≥60 mg/day in 1.9%.ConclusionA high proportion of people with incident bullous pemphigoid are treated with oral prednisolone in UK primary care. Action is required by primary and second care services to encourage use of steroid-sparing alternatives and, where switching is not possible, ensure prophylactic treatments and proactive monitoring of potential side effects are in place.

Modulation of immune functions, inflammatory response, and cytokine production following long-term oral exposure to three food additives; thiabendazole, monosodium glutamate, and brilliant blue in rats

The food additives thiabendazole (TBZ), monosodium glutamate (MSG), and brilliant blue (BB) are commonly used in many daily-consumed food products worldwide. They are widely used in major agricultural and industrial applications. Yet, many of its toxicological aspects are still unclear, especially immune modulation. This research was therefore intended to investigate the effects of male Wistar rats' daily oral exposure for 90 days to TBZ (10 mg/kg b.wt), MSG (20 mg/kg b.wt), or BB (1.2 mg/kg b.wt) on the blood cells, immunity, and inflammatory indicators.The three tested food additives showed varying degrees of hematological alterations. Initially, megaloblastic anemia and thrombocytopenia were evident with the three tested food additives. At the same time, TBZ showed no significant changes in the leukogram element except eosinopenia. MSG induced leukopenia, lymphocytopenia, neutrophilia, and eosinophilia. BB evoked neutrophilia and lymphopenia. The immunoglobins M (IgM) and IgG were significantly reduced with the three tested food additives. In contrast, lysozyme and nitric oxide levels were elevated. A reduced considerably lymphocyte proliferation was detected with TBZ and MSG exposure without affecting the phagocytic activity. Various pathologic disturbances in splenic tissues have been detected. An obvious increase in CD4+ but a lessening in CD8+ immunolabeling was evident in TBZ and MSG groups. The cytokines, including interferon-gamma, tumor necrosis factor-alpha, and interleukin 1β, 6, 10, and 13, were significantly upregulated in the spleen of rats exposed to TBZ, MSG, and BB. These results concluded that TBZ, MSG, and BB negatively affect hematological parameters, innate and humoral immune functions together with inflammatory responses. TBZ achieved the maximal negative impacts followed by MSG and finally with BB. Given the prevalence of these food additives, TBZ and MSG should be limited to a minimal volume use, or natural food additives should be used instead.

Dietary nanoparticles alter the composition and function of the gut microbiota in mice at dose levels relevant for human exposure

BackgroundNanotechnologies provide new opportunities for improving the safety, quality, shelf life, flavor and appearance of foods. The most common nanoparticles (NPs) in human diet are silver metal, mainly present in food packaging and appliances, and silicon and titanium dioxides used as additives. The rapid development and commercialization of consumer products containing these engineered NPs is, however, not well supported by appropriate toxicological studies and risk assessment. Local and systemic toxicity and/or disruption of the gut microbiota (GM) have already been observed after oral administration of NPs in experimental animals, but results are not consistent and doses used were often much higher than the estimated human intakes. In view of the strong evidence linking alterations of the GM to cardiometabolic (CM) diseases, we hypothesized that dietary NPs might disturb this GM-CM axis. Materials and methodsWe exposed male C57BL/6JRj mice (n = 13 per dose group) to dietary NPs mixed in food pellets at doses relevant for human exposure: Ag (0, 4, 40 or 400 μg/kg pellet), SiO2 (0, 0.8, 8 and 80 mg/kg pellet) or TiO2 (0, 0.4, 4 or 40 mg/kg pellet). After 24 weeks of exposure, we assessed effects on the GM and CM health (n = 8 per dose group). The reversibility of the effects was examined after 8 additional weeks without NPs exposure (recovery period, n ≤ 5 per dose group). ResultsNo overt toxicity was recorded. The GM β-diversity was dose-dependently disrupted by the three NPs, and the bacterial short chain fatty acids (SCFAs) were dose-dependently reduced after the administration of SiO2 and TiO2 NPs. These effects disappeared completely or partly after the recovery period, strengthening the association with dietary NPs. We did not observe atheromatous disease or glucose intolerance after NP exposure. Instead, dose-dependent decreases in the expression of IL-6 in the liver, circulating triglycerides (TG) and urea nitrogen (BUN) were recorded after administration of the NPs. ConclusionWe found that long-term oral exposure to dietary NPs at doses relevant for estimated human intakes disrupts the GM composition and function. These modifications did not appear associated with atheromatous or deleterious metabolic outcomes.

Broiler welfare is preserved by long-term low-dose oral exposure to zinc oxide nanoparticles: preliminary study

The potential public health risk through utilizing of zinc oxide nanoparticles (ZnO NPs) in food constitutes the major obstacle to the expansion of nanoparticle (NP) in food industry. Liver histology, bone marrow and liver genotoxicity, immunity, and oxidant status were investigated upon long-term ZnO NPs feed supplementation. One hundred and sixty male IR (Indian River) chicks were randomly allocated to one of the four dietary treatments: control, ZnO NPs at 10, 20, or 40 mg/kg for 42 days. This study revealed non-significant hepatic histopathological alterations and DNA damage and the treatment had no influence on body and organ weights, liver enzymes, lipid peroxidation (MDA), IgG, IgM, and interferon gamma (IFN-γ). This study suggests that low-dose (< 40 mg/kg diet) long-term ZnO NPs supplementation to broiler chicks has no observed potential adverse effects on normal histology of the liver, blood physiology, immune system, and DNA damage of liver and bone marrows, which are critical features for validating ZnO NPs for use in food. Further studies are required to evaluate the probable withdrawal period of ZnO NPs before approval as a dietary supplement in broiler or livestock diets.

Organ and tissue-specific distribution of selected polycyclic aromatic hydrocarbons (PAHs) in ApoE-KO mouse

Polycyclic aromatic hydrocarbons (PAHs) are one of the most prevalent classes of environmental pollutants resulting from the incomplete combustion of hydrocarbons. Exposure to PAHs is implicated in the pathogenesis of the cardiovascular disease, pulmonary disease, and even cancer. However, little is known about organ- and tissue-specific distribution patterns of PAHs in animals at macro-tissue and microscopic levels. Here, by combining GC-MS and single-molecule fluorescence microscopy (SMFM), we revealed the distribution characteristics of four different PAHs (phenanthrene (Phe), pyrene (Pyr), perylene (Per), and benzo[a]pyrene (BaP)) in atherosclerosis model mice (ApoE-KO mice) at macro-tissue and micro-region level after long-term oral exposure. Average PAH concentrations detected by GC-MS in seven tissues ranged from 6.44 to 441 ng/g. The gastrointestinal tract, epididymal fat pat, and lung accumulated higher levels of PAHs, whereas relatively lower PAH residuals were found in the liver, brain, and kidney. Correlation analysis showed that PAHs with higher molecular weight (r: −0.972 to −0.746), Log Kow (r: −0.984 to −0.746) and lower water solubility (r: 0.720 to 0.994) were less prone to bioaccumulate. For the first time, SMFM demonstrated a distinct heterogeneous distribution of Per in the tissue slices. More interestingly, we observed many micro-cluster regions, namely hotspots, showed much higher Per fluorescent intensity than the other common regions. In the area of atherosclerotic plaque, the Per hotspots were colocalized with the micro-regions with the most severe inflammatory response. The hotspots with very high enrichment in PAHs were likely to stimulate the local inflammation and cause excessive damage of the aorta, which resulted in a significant increase of the relative area of atherosclerosis lesion and aggravated atherosclerosis, as observed in PAH exposed mice.

Effect of atrazine on accumulation of iron via the iron transport proteins in the midbrain of SD rats.

Atrazine (ATR), a widely used herbicide that belongs to the triazine class, has detrimental effects on several organ systems. It has also been shown that ATR exposure results in dopaminergic neurotoxicity. However, the mechanism of herbicides causing ferroptosis in neurons is less concerned. So, the present study aimed to investigate the effects of long-term oral exposure to ATR on ferroptosis in adult male rats. In this study, we show that there was a dose-dependent increase in the concentration of iron in the midbrain. Simultaneously, the expression of tyrosine hydroxylase (TH) and Synuclein (α-syn) were altered by the ATR. We carried out miRNA profiling brain tissue in order to identify factors that mediate ferroptosis. We also found that the mRNA and protein expression of the transferrin receptor (TFR), divalent metal transporter 1 (DMT1), hephaestin (HEPH), and ferroportin 1 (Fpn1) in the midbrain were affected by ATR. Based on the current results and previously published data, it is clear that exposure of adult male rats to high doses of ATR leads to iron loading in the midbrain. The long-term adverse effects of ATR on the midbrain have a special relevance after exposure.

Investigation of potential adverse central nervous system effects after long term oral administration of gadolinium in mice.

ObjectivesTo examine potential gadolinium (Gd) accumulation in the brain of healthy mice after long-term oral administration of Gd-containing food pellets and to investigate whether Gd leads to adverse central nervous system (CNS) effects, specifically focussing on locomotor impairment in Gd exposed compared to control animals.Materials and methodsThe local Animal Experimental Ethics Committee approved all procedures and applications. Fifteen female C57Bl/6 mice were orally exposed to a daily intake of 0.57 mmol Gd chloride/ kg body weight over a period of 90 weeks from the age of 4 weeks on. Gd-free, but otherwise equivalent experimental diets were given to the control group (N = 13). The animals were monitored daily by animal caretakers regarding any visible signs of distress and evaluated clinically every four weeks for the first 60 weeks and afterwards every two weeks for a better temporal resolution of potential long-term effects regarding impairment of motor performance and loss of body weight. The individual Gd content was measured using mass spectrometry in a sub-cohort of N = 6 mice.ResultsThe absolute brain Gd levels of the Gd-exposed mice were significantly increased compared to control mice (0.033± 0.009 vs. 0.006± 0.002 nmol Gd/ g brain tissue). Long-term oral Gd exposure over almost the entire life-span did not lead to adverse CNS effects including locomotor changes (rotarod performance, p = 0.1467) in healthy mice throughout the study period. Gd-exposed mice showed less increased body weight compared to control mice during the study period (p = 0.0423). Histopathological alterations, such as hepatocellular vacuolization due to fatty change in the liver and a loss of nucleated cells in the red pulp of the spleen, were found in peripheral organs of both groups.ConclusionsLow levels of intracerebral Gd caused by chronic oral exposure over almost the entire life span of mice did not lead to alterations in locomotor abilities in healthy mice throughout the normal aging process.