Impact of prenatal and postnatal exposure to the pesticide chlorpyrifos on the contraction of rat ileal muscle strips: involvement of an inducible nitric oxide synthase-dependent pathway

Tributyltin (TBT) toxicity: Effects on enteric neuronal plasticity and intestinal barrier of rats' duodenum

Tributyltin (TBT) is a biocide used in the formulation of antifouling paints and it is highly harmful. Despite the ban, the compound persists in the environment, contaminating marine foodstuffs and household products. Therefore, considering the route of exposure to the contaminant, the gastrointestinal tract (GIT) acts as an important barrier against harmful substances and is a potential biomarker for understanding the consequences of these agents. This work aimed to evaluate histological and neuronal alterations in the duodenum of male Wistar rats that received 20 ng/g TBT and 600 ng/g via gavage for 30 consecutive days. After the experimental period, the animals were euthanized, and the duodenum was intended for neuronal histochemistry (total and metabolically active populations) and histological routine (morphometry and histopathology). The results showed more severe changes in neuronal density and intestinal morphometry in rats exposed to 20 ng/g, such as total neuronal density decrease and reduction of intestinal layers. In rats exposed to 600 ng/g of TBT, it was possible to observe only an increase in intraepithelial lymphocytes. We conclude that TBT can be more harmful to intestinal homeostasis when consumed in lower concentrations.

Conceptual DFT, machine learning and molecular docking as tools for predicting LD50 toxicity of organothiophosphates

CONTEXT

Several descriptors from conceptual density functional theory (cDFT) and the quantum theory of atoms in molecules (QTAIM) were utilized in Random Forest (RF), LASSO, Ridge, Elastic Net (EN), and Support Vector Machines (SVM) methods to predict the toxicity (LD₅₀) of sixty-two organothiophosphate compounds. The A-RF-G1 and A-RF-G2 models were obtained using the RF method, yielding statistically significant parameters with good performance, as indicated by R² values for the training set (R²_Train) and R² values for the test set (R²_Test), around 0.90.

METHODS

The molecular structure of all organothiophosphates was optimized via the range-separated hybrid functional ωB97XD with the 6-311 +  + G** basis set. Seven hundred and eighty-seven descriptors have been processed using a variety of machine learning algorithms: RF LASSO, Ridge, EN and SVM to generate a predictive model. The properties were obtained with Multiwfn, AIMALL and VMD programs. Docking simulations were performed by using AutoDock 4.2 and LigPlot + programs. All the calculations in this work are carried out in Gaussian 16 program package.

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

BACKGROUND

Malathion (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.

AIMS

to evaluate the effects of prolonged oral exposure to low levels of MAL on the wall structure and colonic motility parameters of young rats.

MAIN METHODS

The 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 FINDINGS

MAL 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.

SIGNIFICANCE

The 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.

Food Contaminants Effects on an In Vitro Model of Human Intestinal Epithelium

Pesticide residues represent an important category of food contaminants. Furthermore, during food processing, some advanced glycation end-products resulting from the Maillard reaction can be formed. They may have adverse health effects, in particular on the digestive tract function, alone and combined. We sought to validate an in vitro model of the human intestinal barrier to mimic the effects of these food contaminants on the epithelium. A co-culture of Caco-2/TC7 cells and HT29-MTX was stimulated for 6 h with chlorpyrifos (300 μM), acrylamide (5 mM), N^ε-Carboxymethyllysine (300 μM) alone or in cocktail with a mix of pro-inflammatory cytokines. The effects of those contaminants on the integrity of the gut barrier and the inflammatory response were analyzed. Since the co-culture responded to inflammatory stimulation, we investigated whether this model could be used to evaluate the effects of food contaminants on the human intestinal epithelium. CPF alone affected tight junctions’ gene expression, without inducing any inflammation or alteration of intestinal permeability. CML and acrylamide decreased mucins gene expression in the intestinal mucosa, but did not affect paracellular intestinal permeability. CML exposure activated the gene expression of MAPK pathways. The co-culture response was stable over time. This cocktail of food contaminants may thus alter the gut barrier function.

Programming of intestinal homeostasis in male rat offspring after maternal exposure to chlorpyrifos and/or to a high fat diet

Alteration of programming of the intestinal wall maturation may be responsible for non-communicable chronic diseases in adulthood. It may originate from prenatal exposure of mothers to deleterious environmental factors such as pesticides or western diet. This work was undertaken to determine whether disturbances of the digestive tract function and of innate immunity of offspring at adulthood could be due to maternal exposure to a pesticide, chlorpyrifos (CPF) and a High Fat Diet (HFD) starting 4 months before gestation and lasting until weaning of offspring. Fifty-one male Wistar rats coming from 4 groups of dams exposed to CPF, HFD, both and control were followed from birth to 8 weeks of age. They were fed standard chow and received no treatment. The maternal pesticide exposure slows down fetal and postnatal weight gain without histological injuries of the gut mucosa. CPF or HFD both induced modifications of tight junctions and mucins genes expressions without inducing an increase in epithelial permeability or an inflammatory state. Co-exposure to both CPF and HFD did not exacerbate the effects observed with each factor separately. Despite the lack of direct contact except through breast milk until weaning, CPF or HFD maternal exposure have demonstrated preliminary gut barrier impacts on offspring.

Silver bionanoparticles toxicity in trophoblast is mediated by nitric oxide and glutathione pathways

Silver bionanoparticles (AgNPs) biosynthesized by Pseudomonas aeruginosa culture supernatant have an important antibacterial activity mediated by ROS increase; however their toxicity in human cells is not known. Due to the high susceptibility of the developing tissues to xenobiotics, the aim of this study was to investigate the AgNPs effect on first trimester human trophoblasts. The HTR8/SVneo cell line was treated with AgNPs (0.3-1.5 pM), for 6 and 24 h. Cell viability, reactive nitrogen and oxygen species (RNS and ROS) production, nitric oxide synthase expression, antioxidant defenses and biomolecule damage were evaluated. The exposure to AgNPs produced changes in HTR8/SVneo cell morphology and decreased cell viability. Alterations in redox balance were observed, with an increase in ROS and RNS levels, and NOS2 protein expression. Superoxide dismutase and catalase augmented their activity accompanied with a decreased in glutathione content and glutathione S-transferase activity. Protein oxidation and genotoxic damage were observed at concentrations greater than 0.6 pM. The pre-incubation with l-NMMA, NAC, mannitol and peroxidase demonstrated that AgNPs-induced cytotoxicity was not mediated by HO and H₂O₂, but nitric oxide and glutathione pathways were implicated in cell death. Since reported AgNPs microbicidal mechanism is mediated by increasing ROS (mainly HO and H₂O₂) without an increase in RNS, this work indicates an interesting difference in the reactive species and oxidative pathways involved in AgNPs toxicity in eukaryotic and prokaryotic cells. Highlighting the importance of toxicity evaluation to determine the safety of AgNPs with pharmaceutical potential uses.

Neuromodulatory effect of cinnamon oil on behavioural disturbance, CYP1A1, iNOStranscripts and neurochemical alterations induced by deltamethrin in rat brain

The objective of this study was to investigate the influence of deltamethrin (DLM)on brain function and to find whether DLM-induced neurotoxicity is prevented by the treatment with cinnamon oil. Four groups of ten Wistar albino male rats each were used. Group I (control) received saline only. Group II received cinnamon oil alone at 0.5 mg/kg B.W. intraperitonally, whereas Group III received orally DLM alone at 6 mg/kg B.W. Groups IV was treated with cinnamon oil plus DLM for 21 days to induce neurotoxicity. Rat behaviour, brain acetylcholine esterase (AChE), serotonin, oxidative stress profile were assessed. Serum sampling for the assessment of corticosterone concentration was also carried out. Finally, we demonstrate the gene expression of CYP1A1 and iNOS and the histological picture of the brain. Considering the behaviour assessment, DLM administration alone caused neurobehavioral deficits manifested by anxiety-like behavior which represented ina marked decrease in the sleeping frequency and duration, and marked increase the digging frequency and a wake non-active behavior duration. Moreover, the open field result showed a significant decrease in central square entries and duration. The neurochemical analysis revealed that DLM significantly suppressed AChE activity and elevated serotonin and corticosterone concentrations. Furthermore, results revealed thatthe brain reduced glutathione (GSH) content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration were significantly altered in DLM treated rats. Neurochemical disturbances were confirmed by histopathological changes in the brain. Furthermore, DLM up-regulates the mRNA expression of brain CYP1A1 and iNOS. Co-treatment with cinnamon oil exhibited significant improvement in behavioural performance and the brain antioxidant capacities with an increase in AChE activity and diminished the concentration of serotonin, serum corticosterone and MDA. Cinnamon oil treatment resulted in down-regulation of CYP1A1 and iNOS and improve the histologically picture. In conclusion, cinnamon oil ameliorated DLM-induced neurotoxicity through preventing oxidative stress-induced genotoxicity and apoptosis of brain in rats.

Ameliorative Effect of Beta vulgaris Root Extract on Chlorpyrifos-Induced Oxidative Stress, Inflammation and Liver Injury in Rats

Exposure to organophosphorus insecticides causes several health problems to animals and humans. Red beetroot (RBR) is rich in antioxidant ingredients and possesses a promising hepatoprotective activity. This study evaluated the potential of RBR extract to prevent chlorpyrifos (CPF)-induced liver injury, with an emphasis on oxidative stress, inflammation and apoptosis. Rats received 10 mg/kg CPF and were treated with 300 mg/kg RBR extract for 28 days. CPF caused liver injury evidenced by elevated serum levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and bilirubin, along with several histological alterations. Hepatic lipid peroxidation (LPO) and nitric oxide (NO) levels, as well as inducible nitric oxide synthase (iNOS) and pro-inflammatory cytokines were increased in CPF-intoxicated rats. RBR prevented CPF-induced histological alterations, and ameliorated liver function, LPO, NO, iNOS and pro-inflammatory cytokines. RBR boosted glutathione and antioxidant enzymes, and increased Nrf2 expression. In addition, RBR diminished Bax and caspase-3, and increased Bcl-2 expression. In conclusion, RBR prevented CPF-induced liver injury via attenuation of oxidative stress, inflammation and apoptosis. RBR enhanced antioxidant defenses, suggesting that it could be used as a potential therapeutic intervention to minimize CPF hepatotoxicity.

Histopathological effects, responses of oxidative stress, inflammation, apoptosis biomarkers and alteration of gene expressions related to apoptosis, oxidative stress, and reproductive system in chlorpyrifos-exposed common carp (Cyprinus carpio L.)

In this study, we aimed to identify the toxic effects of chlorpyrifos exposure on the tissues of common carp. For this purpose, we evaluated histopathological changes in the brain, gills, liver, kidney, testis, and ovaries after 21 days of chlorpyrifos exposure. Activation of 8-OHdG, cleaved caspase-3, and iNOS were assesed by immunofluorescence assay in chlorpyrifos-exposed brain and liver tissue. Additionally, we measured the expression levels of caspase-3, caspase-8, iNOS, MT1, CYP1A, and CYP3A genes in chlorpyrifos-exposed brain tissue, as well as the expression levels of FSH and LH genes in chlorpyrifos-exposed ovaries, using qRT-PCR. We observed severe histopathological lesions, including inflammation, degeneration, necrosis, and hemorrhage, in the evaluated tissues of common carp after both high and low levels of exposure to chlorpyrifos. We detected strong and diffuse signs of immunofluorescence reaction for 8-OHdG, iNOS, and cleaved caspase-3 in the chlorpyrifos-exposed brain and liver tissues. Furthermore, we found that chlorpyrifos exposure significantly upregulated the expressions of caspase-3, caspase-8, iNOS, and MT1, and also moderately upregulated CYP1A and CYP3A in the brain tissue of exposed carp. We also noted downregulation of FSH and LH gene expressions in chlorpyrifos-exposed ovary tissues. Based on our results, chlorpyrifos toxication caused crucial histopathological lesions in vital organs, induced oxidative stress, inflammation, and apoptosis in liver and brain tissues, and triggered reproductive sterility in common carp. Therefore, we can propose that chlorpyrifos toxication is highly dangerous to the health of common carp. Moreover, chlorpyrifos pollution in the water could threaten the common carp population. Use of chlorpyrifos should be restricted, and aquatic systems should be monitored for chlorpyrifos pollution.