Developmental and cardiac toxicities of propofol in zebrafish larvae

Toxic effects of prolonged propofol exposure on cardiac development in zebrafish larvae

BACKGROUND

Propofol, commonly used as an intravenous anesthetic during pregnancy, can easily penetrate the placental barrier, potentially affecting fetal heart development. This study aims to investigate propofol's impact on developing zebrafish heart structure and function, and identify potential drug targets.

METHODS

Zebrafish embryos were exposed to different concentrations of propofol (0.5, 1, and 5 mg/L) to observe changes in zebrafish larval heart structure and function (heart rate). In vitro cell experiments were conducted to assess the effects of propofol at different concentrations on cardiomyocyte viability and migration. Transcriptomic sequencing was utilized to identify and validate potential drug targets associated with propofol-induced cardiac toxicity.

RESULTS

The results demonstrate that propofol dose-dependently reduces the hatching and survival rates of zebrafish larvae, while increasing the rate of deformities. Transgenic green fluorescent zebrafish larvae exposed to propofol exhibit enlarged cardiac cavities, and HE staining reveals thinning of the myocardial wall. Additionally, propofol-treated zebrafish larvae show a decrease in heart rate. We also assess the impact of propofol on myocardial cell function, showing decreased cell viability, reduced migration function, and increased apoptosis. Finally, transcriptome sequencing analysis and differential gene co-expression network analysis identify agxt2 as a potential target of propofol-induced cardiac toxicity.

CONCLUSION

In conclusion, our study indicates that propofol alters the structure and function of the developing zebrafish heart, with the mitochondrial-related gene agxt2 possibly being a target of its pharmacological effects.

Early developmental effects of propofol exposure in different stages of zebrafish embryos

The mechanism of action of propofol, a common intravenous anaesthetic, in early life stages is not well understood with contradictory studies showing neurotoxic and neurogenic effects in the developing brain. Zebrafish early life stages have been established as an alternative model for animal experimentation with propofol toxicological effects reported following chronic exposure. Yet, the acute exposure to other anaesthetics has been shown to induce early life stage-dependent toxicological outcomes. Therefore, the present study aimed to evaluate the teratogenic effects of propofol at the 256-cell, 50 % epiboly and 1-4 somite stages following a 20 min exposure. Embryos were exposed after primarily assessment of propofol acute toxicity (24h-LC50=9.82 μg mL-1) and absorption at different developmental stages by chromatography. Embryos (2 hours post-fertilization, hpf) were treated with an anaesthetic and toxicological concentration of propofol (2.5 and 10 μg mL-1, respectively) for 20-min. Mortality and developmental toxicity were then evaluated until 144 hpf, when the behaviour and oxidative-stress-related biomarkers were assessed. Exposure at the 256-cell stage resulted in a concentration-dependent increased number of abnormalities in head, fins and tail and a decreased body length as well as in changes in ATPase activity for the lowest concentration. On the other hand, exposure at later stages resulted in a decreased survival while no significant malformations were detected. Yet, exposure during the 50 % epiboly stage resulted in the increase of ROS levels as well as glutathione (GST and GSSG) levels while exposure at 1-4 somite stage resulted in increased DNA damage and ATPase alterations. The behaviour of zebrafish was similar among treatments. Overall, these findings show highlight the stage-dependent teratogenic potential of short propofol exposures during zebrafish early development. The alterations observed may be linked to the activation of the zygotic transcription in embryos, requiring further studies to delve into the molecular changes underlying the observed effects.

Bromuconazole exposure induces cardiac dysfunction by upregulating the expression LEF1

With the wide application of bromuconazole (BRO), a kind of triazole fungicide, the environmental problems caused by BRO have been paid more and more attention. In this study, adult male zebrafish were exposed to environmental related concentration and the maximum non-lethal concentration for zebrafish larvae (0,50 ng/L and 7.5 mg/L) for 7 days, respectively. Zebrafish exposed to BRO exhibited a significant reduction in body length and an increase in fatness index, indicating adverse physiological changes. Notably, the exposed zebrafish showed enlarged heart ventricular volumes and thinner heart walls. Transcriptome analysis of heart samples showed that BRO exposure mainly affected pathways related to cardiac energy metabolism. In addition, the amount of ATP in the heart tissue was correspondingly reduced, and the expression levels of genes related to controlling ion balance and myosin synthesis in the heart were also altered. The study extended its findings to the rat cardiomyocytes (H9C2), where similar cardiotoxic effects including changes in transcription of genes related to energy metabolism and heart function were also observed, suggesting a potential universal mechanism of BRO-induced cardiotoxicity. In a doxorubicin (DOX) induced larval zebrafish heart failure model, the expression of lymphoid enhancer-binding factor 1(LEF1), a key gene in the Wnt/β-catenin signaling pathway, was significantly increased in larval zebrafish and adult fish heart tissues and cardiomyocytes, suggesting that LEF1 might play an important role in BRO-induced cardiotoxicity. Taken together, BRO exposure could interfere with cardiac function and metabolic capacity by abnormal activation the expression of LEF1. The study emphasized the urgent need for monitoring and regulating BRO due to its harmful effects on the hearts of aquatic organisms.

Ecological risk assessment of environmentally relevant concentrations of propofol on zebrafish (Danio rerio) at early life stage: Insight into physiological, biochemical, and molecular aspects

Propofol is an intravenous anesthetic injection extensively used in clinic, which has been proved to be neurotoxic in humans. Improper use and disposal of propofol may lead to its release into the aquatic environment, but the potential ecological risk of propofol to aquatic organisms remains poorly understood. For this study, we comprehensively explored the ecotoxicological effects and potential mechanisms of propofol (0.04, 0.2 and 2 mg L^-1) on 120 hpf zebrafish (Danio rerio) embryos from physiological, biochemical, and molecular perspectives. The results showed that propofol has moderate toxicity on zebrafish embryos (96 h LC₅₀ = 4.260 mg L^-1), which could significantly reduce the hatchability and delay the development. Propofol can trigger reactive oxygen species (ROS) generation, lipid peroxidation (Malondialdehyde, MDA) and DNA damage (8-hydroxy-2-deoxyguanosine, 8-OHdG). The glutathione peroxidase (GPX) activity of zebrafish embryos in 0.04 and 0.2 mg L^-1 propofol treatment group was activated in response to oxidative damage, while activities of superoxide dismutase (SOD), catalase (CAT) and GPX in zebrafish treated with 2 mg L^-1 was significant inhibited compared with the control group (p＜0.05). Moreover, the expression of antioxidant genes and related pathways was inhibited. Apoptosis was investigated at genes level and histochemistry. Molecular docking confirmed that propofol could change in the secondary structure of acetylcholinesterase (AChE) and competitively inhibited acetylcholine (ACh) binding to AChE, which may disturb the nervous system. These results described toxic response and molecular mechanism in zebrafish embryos, providing multiple aspects about ecological risk assessment of propofol in water environment.

Bromuconazole exposure induces cardiotoxicity and lipid transport disorder in larval zebrafish

Bromuconazole (BRO), as one of the typical triazole fungicides, has not been reported on its effects on aquatic organisms. In this study, zebrafish embryos were used as experimental objects to evaluate the toxicity of BRO. In the acute embryo toxicity test, it was observed that the heart rate and growing development were affected by BRO in a concentration-dependent manner, and the half-lethal concentration (LC50) of BRO at 96 h post-fertilization (hpf) was about 11.83 mg/L. Then, low concentrations of BRO (50 ng/L, 0.075 mg/L, 0.3 mg/L, 1.2 mg/L), which were set according to the LC50 and environmental related concentrations, were used to analyze the toxic effects on the different endpoints in larval zebrafish. Interestingly, the transcriptomic analysis found that most different expressed genes (DEGs) could be focused on the pathways of lipid metabolism, myocardial function, glycometabolism, indicating that heart function and lipid metabolism in larval zebrafish were disrupted by BRO. For supporting this idea, we re-exposed the transgenic zebrafish and WT zebrafish embryos, proved that BRO caused damage to heart development and lipid transport on morphological and genetic level, which was consistent with transcriptomic results. In addition, BRO exposure caused oxidative damage in the larvae. Taken together, BRO exposure could affect the myocardial contraction function and lipid transport in larval zebrafish, accompanied by disturbances in the level of oxidative stress, which was of great significance for improving the biotoxicological information of BRO.

Anti-Tumor Active Isopropylated Fused Azaisocytosine-Containing Congeners Are Safe for Developing Danio rerio as Well as Red Blood Cells and Activate Apoptotic Caspases in Human Breast Carcinoma Cells

New isopropylated fused azaisocytosine-containing congeners (I-VI) have previously been reported as promising anticancer drug candidates, so further research on these molecules in the preclinical development phase is fully justified and necessary. For this reason, in the present paper, we assess the toxicity/safety profiles of all the compounds using Danio rerio and red blood cell models, and examine the effect of the most selective congeners on the activation of apoptotic caspases in cancer and normal cells. In order to evaluate the effect of each molecule on the development of zebrafish embryos/larvae and to select the safest compounds for further study, various phenotypic parameters (i.e., mortality, hatchability, heart rate, heart oedema, yolk sac utilization, swim bladder development and body shape) were observed, and the half maximal lethal concentration, the maximal non-lethal concentration and no observed adverse effect concentration for each compound were established. The effect of all the isopropylated molecules was compared to that of an anticancer agent pemetrexed. The lipophilicity-dependent structure-toxicity correlations were also determined. To establish the possible interaction of the compounds with red blood cells, an ex vivo hemolysis test was performed. It was shown that almost all of the investigated isopropylated congeners have no adverse phenotypic effect on zebrafish development during five-day exposure at concentrations up to 50 μM (I-III) or up to 20 μM (IV-V), and that they are less toxic for embryos/larvae than pemetrexed, demonstrating their safety. At the same time, all the molecules did not adversely affect the red blood cells, which confirms their very good hemocompatibility. Moreover, they proved to be activators of apoptotic caspases, as they increased caspase-3, -7 and -9 levels in human breast carcinoma cells. The conducted research allows us to select-from among the anticancer active drug candidates-compounds that are safe for developing zebrafish and red blood cells, suitable for further in vivo pharmacological tests.