OBJECTIVES: The purinergic receptor P2X2 (P2RX2) encodes an ATP-gated ion channel permeable to Na⁺, K⁺, and especially Ca²⁺. Loss-of-function mutations in P2RX2 are known to cause autosomal dominant nonsyndromic deafness 41 (DFNA41), which manifests as high-frequency hearing loss, accelerated presbycusis, and increased susceptibility to noise-induced damage. Zebrafish, owing to their small size, rapid development, high fecundity, transparent embryos, and high gene conservation with humans, provide an ideal model for studying human diseases and developmental mechanisms. This study aims to generate a p2rx2 knockout zebrafish model using CRISPR/Cas9 gene editing system to investigate the effect of p2rx2 deficiency on the auditory system, providing a basis for understanding P2RX2-related hearing loss and developing gene therapy strategies. METHODS: Two CRISPR targets (sgRNA1 and sgRNA2) spaced 47 bp apart were designed within the zebrafish p2rx2 gene. Synthesized sgRNAs and Cas9 protein were microinjected into single-cell stage Tübingen (TU)-strain zebrafish embryos. PCR and gel electrophoresis verified editing efficiency at 36 hours post-fertilization (hpf). Surviving embryos were raised to adulthood (F0), tail-clipped, genotyped, and screened for positive mosaics. F1 heterozygotes were generated by outcrossing, and F2 homozygous mutants were obtained by intercrossing. Polymerase chain reaction (PCR) combined with sequencing verified mutation type and heritability. At 5 days post-fertilization (dpf), YO-PRO-1 staining was used to examine hair cell morphology and count in lateral line neuromasts and the otolith region. Auditory evoked potential (AEP) thresholds at 600, 800, 1 000, and 2 000 Hz were measured in nine 4-month-old wild type and mutant zebrafish per group. RESULTS: A stable p2rx2 knockout zebrafish line was successfully established. Sequencing revealed a 66 bp insertion at the first target site introducing a premature stop codon (TAA), leading to early termination of protein translation and loss of function. Embryos developed normally with no gross malformations. At 5 dpf, mutants exhibited significantly reduced hair cell density in the otolith region compared with wild type, although lateral line neuromasts were unaffected. AEP testing showed significantly elevated auditory thresholds at all 4 frequencies in homozygous mutants compared with wild type (all P<0.001), indicating reduced hearing sensitivity. CONCLUSIONS We successfully generated a p2rx2 loss-of-function zebrafish model using CRISPR/Cas9 technology. p2rx2 deficiency caused hair cell defects in the otolith region and increased auditory thresholds across frequencies, indicating its key role in maintaining zebrafish auditory hair cell function and hearing perception. The phenotype's restriction to the otolith region suggests tissue-specific roles of p2rx2 in sensory organs. This model provides a valuable tool for elucidating the molecular mechanisms of P2RX2-related hearing loss and for screening otoprotective drugs and developing gene therapies.
Animals ; Zebrafish/genetics* ; Receptors, Purinergic P2X2/deficiency* ; CRISPR-Cas Systems/genetics* ; Gene Knockout Techniques ; Phenotype ; Zebrafish Proteins/genetics* ; Disease Models, Animal

The zebrafish has emerged as a powerful model organism in life science owing to its remarkable biological characteristics and wide-ranging applications. This review provides a comprehensive overview of the recent advancements in research on zebrafish within the field of environmental toxicology, highlighting specific studies where this species was used to investigate various pollutants to elucidate their impacts and underlying mechanisms. The findings of these studies underscore the significant potential of zebrafish as a model to gain crucial insights into the ecological consequences of environmental contamination and toxicity pathways. By incorporating cutting-edge technologies such as artificial intelligence (AI), high-throughput screening, and omics approaches, the use of zebrafish as a model organism is poised to significantly accelerate toxicological investigations, promote environmental conservation efforts, contribute to safeguarding human health, and advance sustainable development objectives.
Animals ; Zebrafish ; Ecotoxicology/methods* ; Artificial Intelligence ; Humans ; Models, Animal ; Environmental Pollutants/toxicity*

OBJECTIVES: To explore the mechanism of Lacticaseibacillus paracasei E6 for improving vinorelbine-induced immunosuppression in zebrafish. METHODS: The intestinal colonization of L. paracasei E6 labeled by fluorescein isothiocyanate (FITC) in zebrafish was observed under fluorescence microscope. In a zebrafish model of vinorelbine-induced immunosuppression, the immunomodulatory activity of L. paracasei E6 was assessed by analyzing macrophage and neutrophil counts in the caudal hematopoietic tissue (CHT), the number of T-lymphocyte, and the expressions of interleukin-12 (IL-12) and interferon-γ (IFN-γ). The contents of short-chain fatty acids (SCFAs) in L. paracasei E6 fermentation supernatant and the metabolites of L. paracasei E6 in zebrafish were detected by LC-MS/MS-based targeted metabolomics. The immunomodulatory effects of the SCFAs including sodium acetate, sodium propionate and sodium butyrate were evaluated in the zebrafish model of immunosuppression. RESULTS: After inoculation, green fluorescence of FITC-labeled L. paracasei E6 was clearly observed in the intestinal ball, midgut and posterior gut regions of zebrafish. In the immunocompromised zebrafish model, L. paracasei E6 significantly alleviated the reduction of macrophage and neutrophil counts in the CHT, increased the fluorescence intensity of T-lymphocytes, and promoted the expressions of IL-12 and IFN-γ. Compared with MRS medium, L. paracasei E6 fermentation supernatant showed significantly higher levels of acetic acid, propionic acid and butyric acid, which were also detected in immunocompromised zebrafish following treatment with L. paracasei E6. Treatment of the zebrafish model with sodium acetate and sodium propionate significantly increased macrophage and neutrophil counts in the CHT and effectively inhibited vinorelbine-induced reduction of thymus T cells. CONCLUSIONS L. paracasei E6 can improve vinorelbine-induced immunosuppression in zebrafish through its SCFA metabolites acetic acid and propionic acid.
Animals ; Zebrafish/immunology* ; Acetic Acid/metabolism* ; Propionates/metabolism* ; Fatty Acids, Volatile/metabolism*

OBJECTIVES: To investigate the core targets and immunomodulatory mechanisms of Huoluo Xiaoling Pellet (HLXLP) for promoting tissue repair. METHODS: Network pharmacology and protein-protein interaction network were used to screen active components in HLXLP, the disease-related targets and the core targets, followed by GO and KEGG enrichment analyses and molecular docking to predict the pharmacological mechanisms. The toxicity of HLXLP was evaluated in zebrafish, and in a tissue regeneration model established in 3 dpf zebrafish larvae by amputating 95% of the tail fin, the effects of a formulated zebrafish embryo culture medium and 10, 20, and 40 μg/mL of aqueous extract of HLXLP on tissue regeneration was evaluated; RT-qPCR was performed to detect mRNA expressions of tissue regeneration marker genes and the core target genes. Transgenic zebrafish with fluorescently labeled macrophages and neutrophils were used to observe immune cell migration during tissue regeneration, and macrophage polarization at different stages was assessed with RT-qPCR. RESULTS: We identified a total of 149 intersected targets between HLXLP active components and tissue repair and 5 core targets (AKT1, IL-6, TNF-α, EGFR and STAT3). GO and KEGG analyses suggested that the effects of HLXLP were mediated primarily through the JAK-STAT pathway, adhesion junctions and positive regulation of cell migration. HLXLP was minimally toxic below 40 μg/mL and lethal at 320 μg/mL in zebrafish, and caused renal and pericardial edema and vascular defects above 80 μg/mL. In zebrafish with tail fin amputation, HLXLP significantly promoted tissue regeneration, reduced IL-6 and TNF-α and enhanced AKT1, EGFR and STAT3 mRNA expressions, modulated neutrophil and macrophage recruitment to the injury sites, and regulated M1/M2 macrophage polarization during tissue regeneration. CONCLUSIONS HLXLP promotes zebrafish tail fin regeneration through multiple active components, targets and pathways for immunomodulation of immune cell migration and macrophage polarization to suppress inflammation and accelerate healing.
Animals ; Zebrafish/physiology* ; Animal Fins/drug effects* ; Drugs, Chinese Herbal/pharmacology* ; Regeneration/drug effects* ; Network Pharmacology ; Signal Transduction ; Macrophages

OBJECTIVES: To compare the anti-inflammatory, antibacterial and analgesic effects of Yinqiao Powder (YQS) formulated granules and decoction. METHODS: We first evaluated the anti-inflammatory effects of the two dosage forms of YQS in a LPS-induced RAW 264.7 cell model using RT-qPCR and Western blotting. We further constructed zebrafish models of inflammation by copper sulfate exposure, caudal fin transection, or LPS and Poly (I:C) microinjection, and evaluated anti-inflammatory effects of YQS granules and decoction by examining neutrophil aggregation and HE staining findings. In a mouse model of acute lung injury (ALI) induced by intratracheal LPS instillation, the effects of YQS gavage at 10, 15, and 20 g/kg on lung pathologies were evaluated by calculating lung wet-dry weight ratio and using HE staining, ELISA and Western blotting. The microbroth dilution method was used to evaluate the antibacterial effect of YQS. Mouse pain models established by hot plate and intraperitoneal injection of glacial acetic acid were used to evaluate the analgesic effects of YQS at 10, 15, and 20 g/kg. RESULTS: Both YQS granules and decoction significantly reduced TNF-α, IL-6, and IL-1β expressions and p-STAT3 (Tyr 705) phosphorylation level in LPS-induced RAW 264.7 cells, and obviously inhibited neutrophil aggregation in the zebrafish models. In ALI mice, YQS granules and decoction effectively ameliorated lung injury, lowered lung wet-dry weight ratio, and reduced p-STAT3 (Tyr 705) expression and TNF-α and IL-6 levels. YQS produced obvious antibacterial effect at the doses of 15.63 and 31.25 mg/mL, and significantly reduced body torsion and increased pain threshold in the mouse pain models. CONCLUSIONS The two dosage forms of TQS have similar anti-inflammatory, antibacterial and analgesic effects with only differences in their inhibitory effect on TNF-α, IL-6 and IL-1β mRNA expressions in LPS-induced RAW 264.7 cells.
Animals ; Mice ; Drugs, Chinese Herbal/pharmacology* ; Anti-Inflammatory Agents/pharmacology* ; Analgesics/pharmacology* ; RAW 264.7 Cells ; Zebrafish ; Anti-Bacterial Agents/pharmacology* ; Powders ; Tumor Necrosis Factor-alpha/metabolism* ; Acute Lung Injury/drug therapy* ; Interleukin-6/metabolism* ; Lipopolysaccharides

OBJECTIVES: To develop an E-selectin-targeting nanomedicine delivery system that competitively inhibits E-selectin-neutrophil ligand binding to block neutrophil adhesion to vessels and suppress their recruitment to the lesion sites. METHODS: Doxorubicin hydrochloride (DOX)-loaded liposomes (IEL-Lip/DOX) conjugated with E-selectin-affinity peptide IELLQARC were developed using a post-insertion method. Two formulations [2-1P: Mol(PC): Mol(DPI)=100:1; 2-3P: 100:3] were prepared and their modification density and in vitro release characteristics were determined. Their targeting efficacy was assessed in a cell model of LPS-induced inflammation, a mouse model of acute lung injury (ALI), a rat femoral artery model of physical injury-induced inflammation, and a zebrafish model of local inflammation. RESULTS: The prepared IEL-Lip/DOX 2-1P and 2-3P had peptide modification densities of 4.76 and 7.57 pmoL/cm², respectively. Compared with unmodified liposomes, IEL-Lip/DOX exhibited significantly reduced 48-h cumulative release rates at pH 5.5. In the inflammation cell model, IEL-Lip/DOX showed increased uptake by activated inflammatory endothelial cells, and 2-1P exhibited a higher trans-endothelial ability. In ALI mice, the fluorescence intensity of IEL-Lip/Cy5.5 increased significantly in lung tissues by 53.71% [Z-(2-1P)] and 93.41% [Z-(2-3P)], and 2-1P had an increased distribution by 24.19% in the inflammatory lung tissue compared to normal mouse lung tissue. In rat femoral artery models, 2-1P had greater injured/normal vessel fluorescence intensity contrast. In the zebrafish models, both 2-1P and 2-3P showed increased aggregation at the site of inflammation. CONCLUSIONS This E-selectin-targeting nanomedicine delivery system efficiently targets activated inflammatory endothelial cells to increase drug concentration at the inflammatory site, which sheds light on new strategies for treating neutrophil-mediated inflammatory diseases and practicing the concept of "one drug for multiple diseases".
Animals ; Liposomes ; Rats ; Nanomedicine ; E-Selectin ; Drug Delivery Systems ; Inflammation/drug therapy* ; Mice ; Doxorubicin/analogs & derivatives* ; Zebrafish ; Acute Lung Injury/drug therapy*

OBJECTIVES: To investigate the role of ferroptosis in diquat-induced acute kidney injury (AKI) and its molecular mechanisms. METHODS: Transgenic zebrafish models with Tg (Eco.Tshb:EGFP) labeling of the renal tubules and Tg (lyz:dsRed2) labeling of the neutrophils were both divided into control group, gentamicin (positive control) group, diquat poisoning group, ferroptosis inhibitor group. The indicators of kidney injury, inflammatory response, and ferroptosis were examined in the zebrafish, and the changes in expressions of voltage-dependent anion-selective channel protein 1 (VDAC1) and mitochondrial ferritin (FTMT) were detected using Western blotting. RESULTS: AKI induced by diquat exhibited a significant dose-effect relationship, and the severity of injury was proportional to the exposure concentration. Diquat also caused marked oxidative stress and inflammatory responses in the zebrafish models. Rhodamine metabolism assay and HE staining revealed significantly declined glomerular filtration function of the zebrafish as diquat exposure concentration increased. Immunofluorescence staining highlighted significant changes in the expressions of ferroptosis markers GPX4 and FTH1 in zebrafish renal tissues following diquat exposure. In diquat-exposed zebrafish, treatment with ferrostatin-1, a ferroptosis inhibitor, obviously upregulated GPX4 and downregulated FTH1 expressions and improved the metabolic rate of glucan labeled with rhodamine B. Diquat exposure significantly upregulated the expression of VDAC1 and FTMT in zebrafish, and the application of ferrostatin-1 and VBIT-12 (a VDAC1 inhibitor) both caused pronounced downregulation of FTMT expression. CONCLUSIONS Ferroptosis is a critical mechanism underlying diquat-induced AKI, in which VDAC1 and FTMT play important regulatory roles, suggesting their potential as therapeutic target for AKI caused by diquat.
Animals ; Zebrafish ; Ferroptosis/drug effects* ; Acute Kidney Injury/chemically induced* ; Diquat/toxicity* ; Animals, Genetically Modified ; Voltage-Dependent Anion Channel 1/metabolism* ; Ferritins/metabolism* ; Oxidative Stress

OBJECTIVES: To investigate the efficacy of Lactobacillus plantarum ZG03 (L. plantarum ZG03) for ameliorating oxidative stress in zebrafish. METHODS: We evaluated the growth pattern of L. plantarum ZG03, observed its morphology using field emission scanning electron microscopy, and assessed its safety and potential efficacy with whole-genome sequencing for genetic analysis. FITC-labeled ZG03 was used to observe its intestinal colonization in zebrafish. In a zebrafish model of 2% glucose-induced oxidative stress, the effect of ZG03 was evaluated by assessing the changes in neutrophils in the caudal hematopoietic tissue (CHT), superoxide dismutase (SOD) activity, reactive oxygen species (ROS) levels, and malondialdehyde (MDA) content. Liquid chromatography-mass spectrometry-based targeted metabolomics was used for analyzing short-chain fatty acids (SCFAs) in the zebrafish, and the antioxidant effects of the key metabolites (acetate, propionate, and caproate) were tested. RESULTS: On MRS agar, L. plantarum ZG03 formed circular, smooth, moist, and milky-white colonies with a rod-shaped cell morphology. Genomic analysis revealed abundant sugar metabolism gene clusters. After inoculation of FITC-labeled L. plantarum ZG03 in zebrafish, green fluorescence was clearly observed in the intestinal bulb, mid-intestine, and hind intestine. In zebrafish with glucose-induced oxidative stress, L. plantarum ZG03 significantly reduced ROS levels and the number of neutrophils in the CHT with increased SOD activity. L.plantarum ZG03 significantly increased the content of SCFAs including acetic acid, propionic acid, and caproic acid in zebrafish metabolites. In addition, sodium acetate, sodium propionate, and sodium caproate in the SCFAs significantly increased SOD activity in the zebrafish models. CONCLUSIONS L. plantarum ZG03 ameliorates oxidative stress in a glucose-induced zebrafish model through its metabolites, particularly the SCFAs including acetic acid, propionic acid and caproic acid.
Animals ; Zebrafish/metabolism* ; Oxidative Stress ; Lactobacillus plantarum/metabolism* ; Fatty Acids, Volatile/metabolism* ; Probiotics ; Reactive Oxygen Species/metabolism* ; Superoxide Dismutase/metabolism*

Acute mitochondrial damage and the energy crisis following axonal injury highlight mitochondrial transport as an important target for axonal regeneration. Syntaphilin (Snph), known for its potent mitochondrial anchoring action, has emerged as a significant inhibitor of both mitochondrial transport and axonal regeneration. Therefore, investigating the molecular mechanisms that influence the expression levels of the snph gene can provide a viable strategy to regulate mitochondrial trafficking and enhance axonal regeneration. Here, we reveal the inhibitory effect of microRNA-146b (miR-146b) on the expression of the homologous zebrafish gene syntaphilin b (snphb). Through CRISPR/Cas9 and single-cell electroporation, we elucidated the positive regulatory effect of the miR-146b-snphb axis on Mauthner cell (M-cell) axon regeneration at the global and single-cell levels. Through escape response tests, we show that miR-146b-snphb signaling positively regulates functional recovery after M-cell axon injury. In addition, continuous dynamic imaging in vivo showed that reprogramming miR-146b significantly promotes axonal mitochondrial trafficking in the pre-injury and early stages of regeneration. Our study reveals an intrinsic axonal regeneration regulatory axis that promotes axonal regeneration by reprogramming mitochondrial transport and anchoring. This regulation involves noncoding RNA, and mitochondria-associated genes may provide a potential opportunity for the repair of central nervous system injury.
Animals ; Zebrafish ; MicroRNAs/genetics* ; Nerve Regeneration/physiology* ; Mitochondria/metabolism* ; Zebrafish Proteins/genetics* ; Axons/metabolism* ; Signal Transduction/physiology* ; Axonal Transport/physiology* ; Nerve Tissue Proteins/genetics*

Zebrafish larvae are useful for identifying chemicals against lateral line (LL) hair cell (HC) damage and this type of chemical screen mainly focuses on searching for protectors against cell death. To expand the candidate pool of HC protectors, a self-built acoustic escape response (AER)-detecting system was developed to apply both low-frequency near-field sound transmission and AER image acquisition/processing modules. The device quickly confirmed the changed LL HC functions caused by most known ototoxins, protectors, and neural transmission modifiers, or knockdown of LL HC-expressing genes. With ten devices wired in tandem, five 'hit' chemicals were identified from 124 cyclin-dependent kinase inhibitors to partially restore cisplatin-damaged AER in less than a day. AS2863619, ribociclib, and SU9516 among the hits, protected the HCs in the mouse cochlea. Therefore, using free-swimming larval zebrafish, the self-made AER-detecting device can efficiently identify compounds that are protective against HC damage, including cell death and loss-of-function.
Animals ; Zebrafish ; Hair Cells, Auditory/physiology* ; Lateral Line System/cytology* ; Escape Reaction/physiology* ; Larva ; Mice ; Cisplatin/toxicity* ; Drug Evaluation, Preclinical/methods*