β-cypermethrin-induced acute neurotoxicity in the cerebral cortex of mice

Toxic effect and mechanism of β-cypermethrin and its chiral isomers on HTR-8/SVneo cells

Beta-cypermethrin (β-CYP) consists of four chiral isomers, acting as an environmental estrogen and causing reproductive toxicity, neurotoxicity, and dysfunctions in multiple organ systems. This study investigated the toxic effects of β-CYP, its isomers, metabolite 3-phenoxybenzoic acid (3-PBA), and 17β-estradiol (E2) on HTR-8/SVneo cells. We focused on the toxic mechanisms of β-CYP and its specific isomers. Our results showed that β-CYP and its isomers inhibit HTR-8/SVneo cell proliferation similarly to E2, with 100 μM 1S-trans-αR displaying significant toxicity after 48 h. Notably, 1S-trans-αR, 1R-trans-αS, and β-CYP were more potent in inducing apoptosis and cell cycle arrest than 1R-cis-αS and 1S-cis-αR at 48 h. AO/EB staining and flow cytometry indicated dose-dependent apoptosis in HTR-8/SVneo cells, particularly at 100 μM 1R-trans-αS. Scratch assays revealed that β-CYP and its isomers variably reduced cell migration. Receptor inhibition assays demonstrated that post-ICI 182780 treatment, which inhibits estrogen receptor α (ERα) or estrogen receptor β (ERβ), β-CYP, its isomers, and E2 reduced HTR-8/SVneo cell viability, whereas milrinone, a phosphodiesterase 3 A (PDE3A) inhibitor, increased viability. Molecular docking studies indicated a higher affinity of β-CYP, its isomers, and E2 for PDE3A than for ERα or ERβ. Consequently, β-CYP, its isomers, and E2 consistently led to decreased cell viability. Transcriptomics and RT-qPCR analyses showed differential expression in treated cells: up-regulation of Il24 and Ptgs2, and down-regulation of Myo7a and Pdgfrb, suggesting the PI3K-AKT signaling pathway as a potential route for toxicity. This study aims to provide a comprehensive evaluation of the cytotoxicity of chiral pesticides and their mechanisms.

Characterisation of the heat shock protein Tid and its involvement in stress response regulation in Apis cerana

Objective: The impact of various environmental stresses on native Apis cerana cerana fitness has attracted intense attention in China. However, the defence responses of A. cerana cerana to different stressors are poorly understood. Here, we aimed to elucidate the regulatory mechanism mediated by the tumorous imaginal discs (Tid) protein of A. cerana cerana (AccTid) in response to stressors. Methods: We used some bioinformatics softwares to analyse the characterisation of Tid. Then, qRT-PCR, RNA interference and heat resistance detection assays were used to explore the function of Tid in stress response in A. cerana cerana. Results: AccTid is a homologous gene of human Tid1 and Drosophila Tid56, contains a conserved J domain and belongs to the heat shock protein DnaJA subfamily. The level of AccTid induced expression was increased under temperature increases from 40°C to 43°C and 46°C, and AccTid knockdown decreased the heat resistance of A. cerana cerana, indicating that the upregulation of AccTid plays an important role when A. cerana cerana is exposed to heat stress. Interestingly, contrary to the results of heat stress treatment, the transcriptional level of AccTid was inhibited by cold, H₂O₂ and some agrochemical stresses and showed no significant change under ultraviolet ray and sodium arsenite stress. These results suggested that the requirement of A. cerana cerana for Tid differs markedly under different stress conditions. In addition, knockdown of AccTid increased the mRNA levels of some Hsps and antioxidant genes. The upregulation of these Hsps and antioxidant genes may be a functional complement of AccTid knockdown. Conclusion: AccTid plays a crucial role in A. cerana cerana stress responses and may mediate oxidative damage caused by various stresses. Our findings will offer fundamental knowledge for further investigations of the defence mechanism of A. cerana cerana against environmental stresses.

β-Cypermethrin and its metabolite 3-phenoxybenzoic acid exhibit immunotoxicity in murine macrophages

β-Cypermethrin (β-CYP), one of most important pyrethroids, is widely used to control insects, and has been detected in organisms, including human. Pyrethroids have been shown to pose neurotoxicity, hepatotoxicity, endocrine disruption and reproductive risks in mammals. However, research in immunotoxicity of pyrethroids, especially their metabolites, is limited. A common metabolite of pyrethroids is 3-phenoxybenzoic acid (3-PBA) in mammals. Thus, in this study, we evaluated the immunotoxicity of β-CYP and 3-PBA in mouse macrophages, RAW 264.7 cells. MTT assays showed that both β-CYP and 3-PBA reduced cell viability in a concentration- and time-dependent manner. Flow cytometry with Annexin-V/PI staining demonstrated that both β-CYP and 3-PBA induced RAW 264.7 cell apoptosis. Furthermore, our results also showed that N-acetylcysteine partially blocked β-CYP- and 3-PBA-induced cytotoxicity and apoptosis. Intrinsic apoptotic pathway was stimulated by both β-CYP and 3-PBA exposure. In addition, we found that β-CYP and 3-PBA inhibited mRNA levels of pro-inflammatory cytokines with or without LPS stimulation. Phagocytosis assay showed that both β-CYP and 3-PBA inhibited phagocytic ability of macrophages. Moreover, it was also found that both β-CYP and 3-PBA increased reactive oxygen species (ROS) levels in RAW 264.7 cells. Accordingly, both β-CYP and 3-PBA were found to regulate the mRNA levels of oxidative stress-related genes in RAW 264.7 cells. Taken together, the results obtained in this study demonstrated that β-CYP and 3-PBA may have immunotoxic effect on macrophages and that elevated ROS may underlie the mechanism. The present study will help to understand the health risks caused by β-CYP and other pyrethroids.