Single and Combined Effects of Chlorpyrifos and Glyphosate on the Brain of Common Carp: Based on Biochemical and Molecular Perspective

Maternal exposure to pesticides induces perturbations in the gut microbiota and blood-brain barrier of dams and the progeny, prevented by a prebiotic

Exposure to pesticide residues during the first 1000 days of life can disrupt body homeostasis and contribute to chronic metabolic diseases. Perinatal chlorpyrifos (CPF) exposure alters gut microbiota (GM) balance, potentially affecting offspring's health. Given the GM influence on brain function, the primary aim is to determine if pesticide-induced dysbiosis (microbial imbalance) affects indirectly other organs, such as the blood-brain barrier (BBB). The secondary objective is to evaluate the prebiotics protective effects, particularly inulin in promoting microbial balance (symbiosis), in both mothers and offspring. A total of 15 or more female rats were divided in 4 groups: control, oral CPF-exposed (1 mg/kg/day), exposed to inulin (10 g/L), and co-exposed to CPF and inulin from pre-gestation until weaning of pups. Samples from intestines, spleen, liver, and brain microvessels underwent microbiological and biomolecular analyses. Bacterial culture assessed GM composition of living bacteria and their translocation to non-intestinal organs. RT qPCR and Western blotting detected gene expression and protein levels of tight junction markers in brain microvessels. CPF exposure caused gut dysbiosis in offspring, with decreased Lactobacillus and Bifidobacterium and increased Escherichia coli (p < 0.01) leading to bacterial translocation to the spleen and liver. CPF also decreased tight junction's gene expression levels (50 to 60% decrease of CLDN3, p < 0.05). In contrast, inulin partially mitigated these adverse effects and restored gene expression to control levels. Our findings demonstrate a causal link between GM alterations and BBB integrity disruptions. The protective effects of inulin suggest potential therapeutic strategies to counteract pesticide-induced dysbiosis.

Fenpropathrin disrupted the gills of common carp (Cyprinus carpio L.) through oxidative stress, inflammatory responses, apoptosis, and transcriptional alterations

Fenpropathrin (FEN) is an extensively utilized synthetic pyrethroid insecticide frequently found in aquatic ecosystems. However, the adverse effects and potential mechanisms of FEN on aquatic species are poorly understood. In this work, common carp were treated with FEN at concentrations of 0.45 and 1.35 μg/L FEN for 14 days, after which the tissue structure, physiological alterations, and mRNA transcriptome of the gills were evaluated. Specifically, FEN exposure caused pathological damage to the gills of carp, downregulated the levels of claudin-1, occludin, and zonula occluden-1 (ZO-1), and inhibited Na+-K+-ATPase activity in the gills. In addition, FEN exposure promoted an increase in reactive oxygen species (ROS) levels and significantly upregulated the levels of malondialdehyde (MDA), 8-hydroxy-2 deoxyguanosine (8-OHdG), and protein carbonyl (PC) in the gills. Moreover, the inflammation-related indices (TNF-α, IL-1β, and IFN-γ) and the apoptosis-related parameter caspase-3 were generally increased, especially in the 1.35 μg/L FEN group, and these indices were significantly greater than those in the control group. These findings suggest that FEN exposure can cause oxidative stress, the inflammatory response, and apoptosis in carp gills. Importantly, the results of RNA-seq analysis showed that 0.45 and 1.35 μg/L FEN could significantly interfere with multiple immune and metabolic pathways, including the phagosome, NOD-like receptor (NLR) signalling pathway, Toll-like receptor (TLR) signalling pathway, necroptosis, and arachidonic acid metabolism pathways, indicating that the effects of FEN on the gills of fish are intricate. In summary, our findings confirm the toxic effects of FEN on common carp gills and provide additional comprehensive information for evaluating the toxicity and underlying molecular mechanisms of FEN in aquatic organisms.

Adverse effects of fenpropathrin on the intestine of common carp (Cyprinus carpio L.) and the mechanism involved

Fenpropathrin (FEN), a pyrethroid pesticide, is frequently detected in natural water bodies, unavoidable pose adverse effects to aquatic organisms. However, the harmful effects and potential mechanisms of FEN on aquatic species are poorly understood. In this study, common carp were treatment with FEN at 0.45 and 1.35 μg/L for 14 d, and the toxic effects and underlying mechanisms of FEN on the intestine of carp were revealed. RNA-seq results showed that FEN exposure cause a wide range of transcriptional alterations in the intestine and the differentially expressed genes were mainly enrichment in the pathways related to immune and metabolism. Specifically, FEN exposure induced pathological damage and altered submicroscopic structure of the intestine, elevated the levels of Bacteroides fragilis enterotoxin, altered the contents of claudin-1, occludin, and zonula occluden-1 (ZO-1), and causing injury to the intestinal barrier. In addition, inflammation-related index TNF-α in the serum and IL-6 in the intestinal tissues were generally increased after FEN exposure. Moreover, FEN exposure promoted an increase in reactive oxygen species (ROS), altered the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), upregulated the contents of malondialdehyde (MDA) in the intestines. The apoptosis-related parameter cytochrome c, caspase-9, and caspase-3 were significantly altered, indicating that inflammation reaction, oxidative stress, and apoptosis may be involved in the toxic mechanism of FEN on carp. Moreover, FEN treatment also altered the intestinal flora community significantly, which may affect the intestinal normal physiological function and thus affect the growth of fish. Overall, the present study help to clarify the intestinal reaction mechanisms after FEN treatment, and provide a basis for the risk assessment of FEN.