With the aim to explore the possibility to generate a zebrafish model of renal fibrosis, in this study the fibrogenic renal effect of aristolochic acid I (AAI) after immersion was assessed. This compound is highly nephrotoxic able to elicit renal fibrosis after exposure of rats and humans. Our results reveal that larval zebrafish at 15 days dpf (days post-fertilization) exposed for 8 days to 0.5 µM AAI showed clear signs of AKI (acute kidney injury). The damage resulted in the relative loss of the functional glomerular filtration barrier. Conversely, we did not observe any deposition of collagen, nor could we immunodetect α-SMA, a hallmark of myofibroblasts, in the tubules. In addition, no increase in gene expression of fibrogenesis biomarkers after whole animal RNA extraction was found. As zebrafish have a high capability for tissue regeneration possibly impeding fibrogenic processes, we also used a tert^−/− zebrafish line exhibiting telomerase deficiency and impaired tissue homeostasis. AAI-treated tert^−/− larvae displayed an increased sensitivity towards 0.5 µM AAI. Importantly, after AAI treatment a mild collagen deposition could be found in the tubules. The outcome implies that sustained AKI induced by nephrotoxic compounds combined with defective tert^−/− stem cells can produce a fibrotic response.

In drug discovery, often animal models are used that mimic human diseases as closely as possible. These animal models can be used to address various scientific questions, such as testing and evaluation of new drugs, as well as understanding the pathogenesis of diseases. Currently, the most commonly used animal models in the field of fibrosis are rodents. Unfortunately, rodent models of fibrotic disease are costly and time-consuming to generate. In addition, present models are not very suitable for screening large compounds libraries. To overcome these limitations, there is a need for new in vivo models. Zebrafish has become an attractive animal model for preclinical studies. An expanding number of zebrafish models of human disease have been documented, for both acute and chronic diseases. A deeper understanding of the occurrence of fibrosis in zebrafish will contribute to the development of new and potentially improved animal models for drug discovery. These zebrafish models of fibrotic disease include, among others, cardiovascular disease models, liver disease models (categorized into Alcoholic Liver Diseases (ALD) and Non-Alcoholic Liver Disease (NALD)), and chronic pancreatitis models. In this review, we give a comprehensive overview of the usage of zebrafish models in fibrotic disease studies, highlighting their potential for high-throughput drug discovery and current technical challenges.

Isopropyl 3-(3,4-dihydroxyphenyl)-2-hydroxypropanoate (IDHP) is the core active substance of salvia miltiorrhiza in disease treatment. The significance of our work lies in evaluating the ameliorating effects of IDHP on hypoxia-induced injury and investigating its mechanisms. We examined the morphology, dopamine neurons (DANs), cerebral vessels, and behavior of zebrafish larvae administrated by IDHP/VHC after hypoxia-induction. We next sought to explore its anti-hypoxic mechanisms via transcriptome analysis and qPCR experiments. The results indicated that hypoxia-induced injuries, including decreased length of DANs, number of cereal vessels, total swimming distance, and average swimming speed, were all alleviated by IDHP. Furthermore, transcriptome analysis provided a sign that IDHP most likely played the anti-hypoxic role through the neuroactive ligand-receptor interaction (NLRI) signaling pathway. Consistently, expression of related genes, such as f2rl1.1, p2ry10, npy1r, ptger2b, ptger2b, pth2rb, and nmur1a, was downregulated by hypoxia induction and recovered after IDHP administration. Therefore, we speculated that, via regulating NLRI, IDHP reduced inflammation, promoted angiogenesis, modulated blood pressure and flow, and inhibited cell apoptosis, and eventually played an anti-hypoxic role.

Seven main ginsenosides, including ginsenoside Re, ginsenoside Rb1, pseudoginsenoside F11, ginsenoside Rb2, ginsenoside Rb3, ginsenoside Rd, and ginsenoside F2, were identified by LC-QTOF MS/MS from root, leaf and flower extracts of Panax quinquefolius. These extracts promoted intersegmental vessel growth in a zebrafish model, indicating their potential cardiovascular health benefits. Network pharmacology analysis was then conducted to reveal the potential mechanisms of ginsenoside activity in the treatment of coronary artery disease. GO and KEGG enrichment analyses elucidated that G protein-coupled receptors played a critical role in VEGF-mediated signal transduction and that the molecular pathways associated with ginsenoside activity are involved in neuroactive ligand–receptor interaction, cholesterol metabolism, the cGMP–PKG signaling pathway, etc. Moreover, VEGF, FGF2, and STAT3 were confirmed as the major targets inducing proliferation of endothelial cells and driving the pro-angiogenic process. Overall, ginsenosides could be potent nutraceutical agents that act to reduce the risks of cardiovascular disease. Our findings will provide a basis to utilize the whole P. quinquefolius plant in drugs and functional foods.

Except for clinical value, borneol is routinely used in food and cosmetics with seldom safety evaluation. To investigate its hepatoxicity, we exposed 3 dpf (days post fertilization) larval zebrafish to borneol at a gradient of concentrations (200–500 μM) for 3 days. Herein, our results revealed that high doses of borneol (300–500 μM) caused liver size decrease or lateral lobe absence. Borneol also seriously disturbed the hepatic protein metabolism presented with the increased activity of alanine aminotransferase (ALT) and lipid metabolism shown with the increased level of triglycerides (TG) and total cholesterol (TC). The lipid accumulation (oil red staining) was detected as well. Additionally, significant upregulation of genes was detected that related to oxidative stress, lipid anabolism, endoplasmic reticulum stress (ERS), and autophagy. Conversely, the lipid metabolism-related genes were markedly downregulated. Moreover, the changes in the superoxide dismutase activity and the level of glutathione and malondialdehyde raised the likelihood of lipid peroxidation. The outcomes indicated the involvement of oxidative stress, ERS, lipid metabolism, and autophagy in borneol-induced lipid metabolic disorder and hepatic injury. This study will provide a more comprehensive understanding of borneol hepatoxicity and the theoretical basis for the safe use of this compound.