Propamocarb exposure decreases the secretion of neurotransmitters and causes behavioral impairments in mice.

Propamocarb (PM) is a type of fungicide, which is widely used in the greenhouse-based production of vegetables and fruits globally. It has been considered to have generally low toxicity. However, the teratogenicity or neurotoxicity for mammals remains unclear. In this study, we aimed to explore its effect on the secretion of neurotransmitters and behavioral impairments. Male adult mice were exposed to 10 and 40 mg/L PM for 2 weeks (acute exposure) or 3 and 10 mg/L PM for 10 weeks (chronic exposure). It was observed that acute or chronic exposure to PM changed the levels of serotonin (5-HT) and dopamine in the serum and colon and the transcription of TPH2 and DRD2 in the colons of mice. In addition, the locomotor test, the open field test, and the Morris water maze analysis also showed that acute exposure to PM caused behavioral impairments to some extent. The results obtained in the present study indicated that PM has the potential to induce neurotoxicity in animals.

Exploring HIV-1 transmission features among older individuals in developed eastern China.

The number of newly reported HIV-1 infections among older individuals (aged ≥50 years) has increased rapidly in Hangzhou, a central city in the Yangtze River Delta region of China. To provide a scientific basis for prevention and intervention strategies targeted at older individuals in Hangzhou, an epidemiological survey combined with molecular transmission network analysis was conducted. A total of 2899 individuals with newly confirmed HIV-1 infections, including 635 older individuals and 2264 younger individuals (aged <50 years), were enrolled in this study. Among older individuals, heterosexual contact was the predominant mode of HIV-1 transmission. Additionally, it was observed that older individuals with lower levels of education exhibited a higher susceptibility to HIV-1 infection. The analysis of transmission network which was inferred using HIV-TRACE algorithm revealed that the newly diagnosed HIV-1 infections among older individuals in Hangzhou exhibited a pattern of scattered transmission, with key clusters primarily located in non-main urban areas. The predominant mode of transmission in these areas was non-marital and non-commercial or non-marital and commercial heterosexual transmission. Notably, the study highlighted a significant proportion of older individuals (73.3%, 11/15) within B subtype. Multivariate logistic regression analysis further revealed that the subtype B was a significant factor associated with older individuals having ≥3 node degrees in the network, occurring 5.55 times more frequent than subtype CRF07_BC (95% CI = 1.17-26.22, p = 0.031). Furthermore, the lower CD4 levels observed among older individuals underscored the challenge of late diagnosis in Hangzhou. Taken together, it is imperative to test and intervene for high-risk older individuals. To tackle this issue effectively, it is essential to enhance the detection of the B subtype and implement targeted interventions in key clusters within non-main urban areas. Additionally, proactive measures should be implemented to address the challenge of late diagnosis in Hangzhou by promoting widespread testing among the older individuals, particularly in priority areas.

Exposure to the fungicide propamocarb causes gut microbiota dysbiosis and metabolic disorder in mice.

Propamocarb (PM) is a widely used fungicide with property of affecting fatty acid and phospholipid biosynthesis in funguses. In this study, we explored its effects on mice gut microbiota and metabolism by exposing mice to 3, 30, and 300 mg/L PM through drinking water for a duration of 28 days. We observed that the transcription of hepatic genes related to regulate lipid metabolism were perturbed by PM exposure. The microbiota in the cecal contents and feces changed during or after PM exposure at phylum or genus levels. 16S rRNA gene sequencing for the cecal content revealed shifted in overall microbial structure after PM exposure, and operational taxonomic unit (OTU) analysis indicated that 32.2% of OTUs changed by 300 mg/mL PM exposure for 28 days. In addition, based on 1H NMR analysis,a total of 20 fecal metabolites mainly including succinate, short chain fatty acids, bile acids and trimethylamine were found to be significantly influenced by exposure to 300 mg/L PM.,. These metabolites were tightly correlated to host metabolism. Our findings indicated that high doses of PM exposure could disturb mice metabolism through, or partly through, altering the gut microbiota and microbial metabolites.

Insights Into a Possible Influence on Gut Microbiota and Intestinal Barrier Function During Chronic Exposure of Mice to Imazalil.

The fungicide imazalil (IMZ) is widely used to prevent and treat fungal diseases in plants and animals. Here, male adult C57BL/6 mice were exposed to 0.1, 0.5, and 2.5 mg/kg body weight IMZ for 2, 5, or 15 weeks. The microbiota in cecal contents and feces changed during chronic IMZ exposure at phylum and genus levels. Sequencing of the V3-V4 region of the bacterial 16S rRNA gene revealed a significant change in the richness of microbiota in cecal contents and feces after exposure to 2.5 mg/kg IMZ for 15 weeks. Operational taxonomic unit (OTU) analysis indicated that 31.1% of cecal OTUs and 14.0% of fecal OTUs changed after IMZ exposure. In addition, chronic IMZ exposure also disturbed the intestinal barrier function of the mice, reducing mucus secretion, decreasing the expression of cystic fibrosis transmembrane conductance regulator (CFTR)-related genes in both the ileum and colon. Molecular docking analysis revealed that key hydrogen bonds were formed by nitrogen atoms of the imidazole bond with Val440 of CFTR and Ala697 of the SLC26 family. Our data suggested that gut microbiota and intestinal barrier were potential toxicological targets of IMZ.

Chronic exposure to fungicide propamocarb induces bile acid metabolic disorder and increases trimethylamine in C57BL/6J mice.

Propamocarb (PM) is a widely used fungicide that affects lipid biosynthesis in fungi. In this study, we explored the effects of PM on mouse metabolism and gut microbiota-related pathways by exposing C57BL/6J mice to 1, 3, and 10 mg/L PM through drinking water for a duration of 10 weeks. We found that hepatic bile acids (BAs) were considerably increased in the PM-treated group. The transcription of genes related to BA synthesis and transportation were also markedly altered in the liver and the ileum; accordingly, serous BA profiles were changed. BAs are tightly associated with energy metabolism and the gut microbiota; as expected, we observed that hepatic glycolysis; ß-oxidation; fatty acid transportation, release and synthesis; and triacylglycerol synthesis and transportation were significantly altered at the transcriptional level. Gut microbial community structures were significantly changed both in cecal contents and feces. Using Linear discriminant analysis Effect Size (LEfSe), we found that Chloroflexi, Bacteroidetes and Actinobacteria phyla; Prevotellaceae, Odoribacteraceae and Porphyromonadaceae families; and Butyricimonas, Oscillospira, Parabacteroides, Prevotella and Dorea genera enriched in PM-treated mice. Fecal metabolites involved in energy metabolism were likewise altered. In addition, the atherosclerosis-promoting molecule trimethylamine was significantly increased in feces, which induced a disturbance in the cardiac NO/NOS pathway and an increase in NF-κB transcriptional levels. Our findings indicated that chronic PM exposure induced disorders in enterohepatic metabolism and had potential to increase the risk of cardiovascular disease.

Effects of environmental pollutants on gut microbiota.

Environmental pollutants have become an increasingly common health hazard in the last several decades. Recently, a number of studies have demonstrated the profound relationship between gut microbiota and our health. Gut microbiota are very sensitive to drugs, diet, and even environmental pollutants. In this review, we discuss the possible effects of environmental pollutants including antibiotics, heavy metals, persistent organic pollutants, pesticides, nanomaterials, and food additives on gut microbiota and their subsequent effects on health. We emphasize that gut microbiota are also essential for the toxicity evaluation of environmental pollution. In the future, more studies should focus on the relationship between environmental pollution, gut microbiota, and human health.

From the Cover: Exposure to Oral Antibiotics Induces Gut Microbiota Dysbiosis Associated with Lipid Metabolism Dysfunction and Low-Grade Inflammation in Mice.

Due to a long history of improper and excessive use, Penicillin G (Pen G) and erythromycin (Ery) are regularly detected in environmental samples and pose a great threat to human health. Here, we set out to investigate effects of Pen G, Ery or their mixture on lipid metabolism and gut microbiota in order to better understand their toxicological mechanisms. Male C57BL/6J mice were exposed either to 60 µg/ml Pen G, Ery or a half mixture of both for 6 weeks or to 10 µg/ml Pen G, Ery or a half mixture of both for 14 weeks. In a recovery experiment, male mice were exposed to 60 µg/ml Pen G or Ery for 2 weeks and then maintained without antibiotics for up to 8 weeks. It was observed that oral exposure to Pen G, Ery or their mixture induced lipid metabolism dysfunction, characterized by significantly increased lipid accumulations, triglycerides (TG) levels and expression of key genes involved in free fatty acid (FFA) synthesis, FFA transport and TG synthesis in the liver. In addition, Pen G and Ery exposure induced an inflammatory response as indicated by the increase of serum lipopolysaccharide levels and the up-regulation of key genes that regulate immune responses in the liver, fat, colon and ileum. Moreover, Pen G and Ery exposure rapidly and dramatically altered the composition of the microbiota in feces and cecum. Furthermore, high throughput sequencing of V3-V4 region of bacterial 16S rRNA gene revealed additional significant changes in the cecal microbiota of antibiotics-treated mice. Importantly, it took a very long time to reconstitute the normal composition of the gut microbiota after it was imbalanced by antibiotics exposure. Orally administered Pen G and Ery (especially to the latter) can induce gut microbiota dysbiosis, which may indirectly link antibiotic exposure to host metabolic disorders and inflammation.