Antibiotic toxicity and absorption in zebrafish using liquid chromatography-tandem mass spectrometry

Brief exposure to (-) THC affects zebrafish embryonic locomotion with effects that persist into the next generation

Cannabis is one of the most widely used drugs, and yet an understanding of its impact on the human brain and body is inconclusive. Medicinal and recreational use of cannabis has increased in the last decade with a concomitant increase in use by pregnant women. The major psychoactive compound in cannabis, Δ9-tetrahydrocannabinol (THC), exists in different isomers, with the (-) trans isomer most common. Prenatal exposure to THC can alter neural and behavioral development, but it is unknown how exposure to (-) trans-THC ((-)THC) during very early stages of development impacts fetal growth and movement, and whether effects persist to adulthood, or into the next generation. Here we exposed zebrafish (Danio rerio) to a single exposure of (-)THC (0.001 mg/L (3.2 nM) to 20 mg/L (63.6 µM), for 5 h) during gastrulation (5.25 hpf to 10.75 hpf) when key neurons involved in locomotion such as the primary motor neurons and Mauthner cell first appear. We then examined the impact on embryo morphology and locomotion, adult behavior, and locomotion in the next (F1) generation. Embryos treated with (-)THC experienced changes in morphology, were shorter in length and experienced altered hatching and survival. Spontaneous coiling of 1 dpf embryos was reduced, swimming after touch-evoked responses was reduced and basal swimming in 5 dpf larvae was also reduced. Adult zebrafish tested in the open field test and novel object approach test demonstrated no differences in locomotion, anxiety-like behavior, nor boldness, compared to controls. The (-)THC F1 generation embryos at 1 dpf showed reduced coiling activity, while swimming after touch-evoked responses was reduced in 2 dpf animals but basal swimming at 5 dpf remained similar to controls. Taken together, exposure to (-)THC only once for 5 h during gastrulation has a significant impact on locomotion in embryos and larvae, a minimal impact on adult behavior, and effects that persist into the next generation.

The Impact of Tetracycline Pollution on the Aquatic Environment and Removal Strategies

Antibacterial drugs are among the most commonly used medications in the world. Tetracycline is a widely used antibiotic for human and animal therapy due to its broad-spectrum activity, high effectiveness, and reasonable cost. The indications for treatment with tetracycline include pneumonia, bone and joint infections, infectious disorders of the skin, sexually transmitted and gastrointestinal infections. However, tetracycline has become a serious threat to the environment because of its overuse by humans and veterinarians and weak ability to degrade. Tetracycline is capable of accumulating along the food chain, causing toxicity to the microbial community, encouraging the development and spread of antibiotic resistance, creating threats to drinking and irrigation water, and disrupting microbial flora in the human intestine. It is essential to address the negative impact of tetracycline on the environment, as it causes ecological imbalance. Ineffective wastewater systems are among the main reasons for the increased antibiotic concentrations in aquatic sources. It is possible to degrade tetracycline by breaking it down into small molecules with less harmful or nonhazardous effects. A range of methods for physical, chemical, and biological degradation exists. The review will discuss the negative effects of tetracycline consumption on the aquatic environment and describe available removal methods.

A Rapid Assessment Model for Liver Toxicity of Macrolides and an Integrative Evaluation for Azithromycin Impurities

Impurities in pharmaceuticals of potentially hazardous materials may cause drug safety problems. Macrolide antibiotic preparations include active pharmaceutical ingredients (APIs) and different types of impurities with similar structures, and the amount of these impurities is usually very low and difficult to be separated for toxicity evaluation. Our previous study indicated that hepatotoxicity induced by macrolides was correlated with c-fos overexpression. Here, we report an assessment of macrolide-related liver toxicity by ADMET prediction, molecular docking, structure–toxicity relationship, and experimental verification via detection of the c-fos gene expression in liver cells. The results showed that a rapid assessment model for the prediction of hepatotoxicity of macrolide antibiotics could be established by calculation of the -CDOCKER interaction energy score with the FosB/JunD bZIP domain and then confirmed by the detection of the c-fos gene expression in L02 cells. Telithromycin, a positive compound of liver toxicity, was used to verify the correctness of the model through comparative analysis of liver toxicity in zebrafish and cytotoxicity in L02 cells exposed to telithromycin and azithromycin. The prediction interval (48.1∼53.1) for quantitative hepatotoxicity in the model was calculated from the docking scores of seven macrolide antibiotics commonly used in clinics. We performed the prediction interval to virtual screening of azithromycin impurities with high hepatotoxicity and then experimentally confirmed by liver toxicity in zebrafish and c-fos gene expression. Simultaneously, we found the hepatotoxicity of azithromycin impurities may be related to the charge of nitrogen (N) atoms on the side chain group at the C5 position via structure–toxicity relationship of azithromycin impurities with different structures. This study provides a theoretical basis for improvement of the quality of macrolide antibiotics.

Shifting the focus of zebrafish toward a model of the tumor microenvironment

Cancer cells exist in a complex ecosystem with numerous other cell types in the tumor microenvironment (TME). The composition of this tumor/TME ecosystem will vary at each anatomic site and affects phenotypes such as initiation, metastasis, and drug resistance. A mechanistic understanding of the large number of cell-cell interactions between tumor and TME requires models that allow us to both characterize as well as genetically perturb this complexity. Zebrafish are a model system optimized for this problem, because of the large number of existing cell-type-specific drivers that can label nearly any cell in the TME. These include stromal cells, immune cells, and tissue resident normal cells. These cell-type-specific promoters/enhancers can be used to drive fluorophores to facilitate imaging and also CRISPR cassettes to facilitate perturbations. A major advantage of the zebrafish is the ease by which large numbers of TME cell types can be studied at once, within the same animal. While these features make the zebrafish well suited to investigate the TME, the model has important limitations, which we also discuss. In this review, we describe the existing toolset for studying the TME using zebrafish models of cancer and highlight unique biological insights that can be gained by leveraging this powerful resource.

Zebrafish Model for Studying Dexamethasone-Induced Muscle Atrophy and Preventive Effect of Maca (Lepidium meyenii)

Loss of myofibers during muscle atrophy affects functional capacity and quality of life. Dexamethasone, an inducer of rapid atrophy of skeletal myofibers, has been studied as a glucocorticoid receptor in muscle atrophy or motor neurodegeneration. In this study, we examined dexamethasone-induced muscle atrophy using zebrafish (Danio rerio), a vertebrate model, and assessed whether administration of Lepidium meyenii (maca) as a dietary supplement can prevent muscle atrophy. Changes in skeletal myofibers in zebrafish were evaluated after exposure to dexamethasone for different periods and at different concentrations. Under optimized conditions, zebrafish pre-fed with maca for 3 days were exposed to 0.01% dexamethasone for 1 h/day for 7 days. Thereafter, myofiber loss, damaged muscle contractile proteins, and abnormal exploratory behavior due to the structural and functional impairment of skeletal muscle associated with muscle atrophy were investigated using hematoxylin-eosin, immunofluorescence staining, and behavioral analyses. Our findings suggest that dexamethasone induces muscle atrophy in zebrafish, inhibiting exploratory behavior by inducing myofiber loss, inhibiting muscle contraction, and causing changes in endurance and velocity. Thus, the zebrafish model can be used to screen pharmaceutical agents and to study muscle atrophy. Furthermore, maca is a potential dietary supplement to prevent muscle atrophy, as it protects muscle fibers.

Preclinical Toxicity and Safety of MM-129-First-in-Class BTK/PD-L1 Inhibitor as a Potential Candidate against Colon Cancer

MM-129 is a novel inhibitor targeting BTK/PI3K/AKT/mTOR and PD-L1, as it possesses antitumor activity against colon cancer. To evaluate the safety profile of MM-129, we conducted a toxicity study using the zebrafish and rodent model. MM-129 was also assessed for pharmacokinetics features through an in vivo study on Wistar rats. The results revealed that MM-129 exhibited favorable pharmacokinetics with quick absorption and 68.6% of bioavailability after intraperitoneal administration. No serious adverse events were reported for the use of MM-129, confirming a favorable safety profile for this compound. It was not fatal and toxic to mice at an anticancer effective dose of 10 μmol/kg. At the end of 14 days of administering hematological and biochemical parameters, liver and renal functions were all at normal levels. No sublethal effects were either detected in zebrafish embryos treated with a concentration of 10 μM. MM-129 has the potential as a safe and well-tolerated anticancer formulation for future treatment of patients with colon cancer.

Systematic Roadmap for Cancer Drug Screening Using Zebrafish Embryo Xenograft Cancer Models: Melanoma Cell Line as a Case Study

Simple Summary

Currently, there is no consensus in the scientific literature regarding the zebrafish embryo xenotransplantation procedure for drug screening. Thus, this study sets systematic guidelines for maximizing the reproducibility of drug screening in zebrafish-embryo cancer xenograft models based on evaluating every step of the procedure in a real case scenario in which the chemical properties of the compounds are unknown or not optimal. It aims to be a stepping stone to bring the versatility of zebrafish embryos to drug screening for cancer. The present work helps our group to pursue the objective of establishing zebrafish embryos as a valuable alternative to mice models; and hopefully, will help other groups in this field to progress in the same direction.

Abstract

Zebrafish embryo tumor transplant models are widely utilized in cancer research. Compared with traditional murine models, the small size and transparency of zebrafish embryos combined with large clutch sizes that increase statistical power and cheap husbandry make them a cost-effective and versatile tool for in vivo drug discovery. However, the lack of a comprehensive analysis of key factors impacting the successful use of these models impedes the establishment of basic guidelines for systematic screening campaigns. Thus, we explored the following crucial factors: (i) user-independent inclusion criteria, focusing on sample homogeneity; (ii) metric definition for data analysis; (iii) tumor engraftment criteria; (iv) image analysis versus quantification of human cancer cells using qPCR (RNA and gDNA); (v) tumor implantation sites; (vi) compound distribution (intratumoral administration versus alternative inoculation sites); and (vii) efficacy (intratumoral microinjection versus compound solution in media). Based on these analyses and corresponding assessments, we propose the first roadmap for systematic drug discovery screening in zebrafish xenograft cancer models using a melanoma cell line as a case study. This study aims to help the wider cancer research community to consider the adoption of this versatile model for cancer drug screening projects.

Zebrafish as a Screening Model to Study the Single and Joint Effects of Antibiotics

The overuse of antibiotics combined with the limitation of wastewater facilities has resulted in drug residue accumulation in the natural environment. Thus, in recent years, the presence of antibiotic residues in the environment has raised concerns over the potential harmful effects on ecosystems and human health. The in vivo studies represent an essential step to study the potential impact induced by pharmaceutical exposure. Due to the limitations of traditional vertebrate model systems, zebrafish (Danio rerio) has recently emerged as a promising animal model to study the toxic effects of drugs and their therapeutic efficacy. The present review summarizes the recent advances made on the toxicity of seven representative classes of antibiotics, namely aminoglycosides, β-lactams, macrolides, quinolones, sulfonamides, tetracyclines and polyether antibiotics, in zebrafish, as well as the combined effects of antibiotic mixtures, to date. Despite a significant amount of the literature describing the impact of single antibiotic exposure, little information exists on the effects of antibiotic mixtures using zebrafish as an animal model. Most of the research papers on this topic have focused on antibiotic toxicity in zebrafish across different developmental stages rather than on their efficacy assessment.

Medium-throughput zebrafish optogenetic platform identifies deficits in subsequent neural activity following brief early exposure to cannabidiol and Δ9-tetrahydrocannabinol

In light of legislative changes and the widespread use of cannabis as a recreational and medicinal drug, delayed effects of cannabis upon brief exposure during embryonic development are of high interest as early pregnancies often go undetected. Here, zebrafish embryos were exposed to cannabidiol (CBD) and Δ⁹-tetrahydrocannabinol (THC) until the end of gastrulation (1-10 h post-fertilization) and analyzed later in development (4-5 days post-fertilization). In order to measure neural activity, we implemented Calcium-Modulated Photoactivatable Ratiometric Integrator (CaMPARI) and optimized the protocol for a 96-well format complemented by locomotor analysis. Our results revealed that neural activity was decreased by CBD more than THC. At higher doses, both cannabinoids could dramatically reduce neural activity and locomotor activity. Interestingly, the decrease was more pronounced when CBD and THC were combined. At the receptor level, CBD-mediated reduction of locomotor activity was partially prevented using cannabinoid type 1 and 2 receptor inhibitors. Overall, we report that CBD toxicity occurs via two cannabinoid receptors and is synergistically enhanced by THC exposure to negatively impact neural activity late in larval development. Future studies are warranted to reveal other cannabinoids and their receptors to understand the implications of cannabis consumption on fetal development.

Zebrafish Avatar to Develop Precision Breast Cancer Therapies

BACKGROUND

Zebrafish (Danio rerio) is a vertebrate that has become a popular alternative model for the cellular and molecular study of human tumors and for drug testing and validating approaches. Notably, zebrafish embryos, thanks to their accessibility, allow rapid collection of in vivo results prodromal to validation in the murine models in respect to the 3R principles. The generation of tumor xenograft in zebrafish embryos and larvae, or zebrafish avatar, represents a unique opportunity to study tumor growth, angiogenesis, cell invasion and metastatic dissemination, interaction between tumor and host in vivo avoiding immunogenic rejection, representing a promising platform for the translational research and personalized therapies.

OBJECTIVE

In this mini-review we report recent advances in breast cancer research and drug testing that took advantage of the zebrafish xenograft model using both breast cancer cell lines and patient's biopsy.

CONCLUSION

Patient derived xenograft, together with the gene editing, the omics biotechnology, the in vivo time lapse imaging and the high-throughput screening that are already set up and largely used in zebrafish, could represent a step forward towards precision and personalized medicine in the breast cancer research field.

Benefits of Zebrafish Xenograft Models in Cancer Research

As a promising in vivo tool for cancer research, zebrafish have been widely applied in various tumor studies. The zebrafish xenograft model is a low-cost, high-throughput tool for cancer research that can be established quickly and requires only a small sample size, which makes it favorite among researchers. Zebrafish patient-derived xenograft (zPDX) models provide promising evidence for short-term clinical treatment. In this review, we discuss the characteristics and advantages of zebrafish, such as their transparent and translucent features, the use of vascular fluorescence imaging, the establishment of metastatic and intracranial orthotopic models, individual pharmacokinetics measurements, and tumor microenvironment. Furthermore, we introduce how these characteristics and advantages are applied other in tumor studies. Finally, we discuss the future direction of the use of zebrafish in tumor studies and provide new ideas for the application of it.

Early Exposure to THC Alters M-Cell Development in Zebrafish Embryos

Cannabis is one of the most commonly used illicit recreational drugs that is often taken for medicinal purposes. The psychoactive ingredient in cannabis is Δ⁹-Tetrahydrocannabinol (Δ⁹-THC, hereafter referred to as THC), which is an agonist at the endocannabinoid receptors CB₁R and CB₂R. Here, we exposed zebrafish embryos to THC during the gastrulation phase to determine the long-term effects during development. We specifically focused on reticulospinal neurons known as the Mauthner cells (M-cell) that are involved in escape response movements. The M- cells are born during gastrulation, thus allowing us to examine neuronal morphology of neurons born during the time of exposure. After the exposure, embryos were allowed to develop normally and were examined at two days post-fertilization for M-cell morphology and escape responses. THC treated embryos exhibited subtle alterations in M-cell axon diameter and small changes in escape response dynamics to touch. Because escape responses were altered, we also examined muscle fiber development. The fluorescent labelling of red and white muscle fibers showed that while muscles were largely intact, the fibers were slightly disorganized with subtle but significant changes in the pattern of expression of nicotinic acetylcholine receptors. However, there were no overt changes in the expression of nicotinic receptor subunit mRNA ascertained by qPCR. Embryos were allowed to further develop until 5 dpf, when they were examined for overall levels of movement. Animals exposed to THC during gastrulation exhibited reduced activity compared with vehicle controls. Together, these findings indicate that zebrafish exposed to THC during the gastrula phase exhibit small changes in neuronal and muscle morphology that may impact behavior and locomotion.

Preliminary safety assessment of oridonin in zebrafish

Context: Oridonin, isolated from the leaves of Isodon rubescens (Hemsl.) H.Hara (Lamiaceae), has good antitumor activity. However, its safety in vivo is still unclear. Objective: To investigate the preliminary safety of oridonin in zebrafish. Materials and methods: Embryo, larvae and adult zebrafish (n = 40) were used. Low, medium and high oridonin concentrations (100, 200 and 400 mg/L for embryo; 150, 300 and 600 mg/L for larvae; 200, 400 and 800 mg/L for adult zebrafish) and blank samples were administered. At specific stages of zebrafish development, spontaneous movement, heartbeat, hatching rate, etc., were recorded to assess the developmental effects of oridonin. VEGFA, VEGFR2 and VEGFR3 gene expression were also examined. Results: Low-dose oridonin increased spontaneous movement and hatching rate with median effective doses (ED₅₀) of 115.17 mg/L at 24 h post-fertilization (hpf) and 188.59 mg/L at 54 hpf, but these values decreased at high doses with half maximal inhibitory concentrations (IC₅₀) of 209.11 and 607.84 mg/L. Oridonin decreased heartbeat with IC₅₀ of 285.76 mg/L at 48 hpf, and induced malformation at 120 hpf with half maximal effective concentration (EC₅₀) of 411.94 mg/L. Oridonin also decreased body length with IC₅₀ of 324.78 mg/L at 144 hpf, and increased swimming speed with ED₅₀ of 190.98 mg/L at 120 hpf. The effects of oridonin on zebrafish embryo development may be attributed to the downregulation of VEGFR3 gene expression. Discussions and conclusions: Oridonin showed adverse effects at early stages of zebrafish development. We will perform additional studies on mechanism of oridonin based on VEGFR3.

An overview of cephalosporin antibiotics as emerging contaminants: a serious environmental concern

Antibiotics have been categorized as emerging pollutants due to their indiscriminate usage, continuous input and persistence in various environmental matrices even at lower concentrations. Cephalosporins are the broad-spectrum antibiotics of β-lactam family. Owing to its enormous production and consumption, it is reported as the second most prescribed antibiotic classes in Europe. The cephalosporin wastewater contains toxic organic compounds, inorganic salts, and active pharmaceutical ingredients (API) which pose a potential threat to the organisms in the environment. Therefore, removal of cephalosporin antibiotics from the environment has become mandatory as it contributes to increase in the level of chemical oxygen demand (COD), causing toxicity of the effluent and production of cephalosporin-resistant microbes. So far, several processes have been reported for degradation/removal of cephalosporins from the environment. A number of individual studies have been published within the last decade covering the various aspects of antibiotics. However, a detailed compilation on cephalosporin antibiotics as an emerging environmental contaminant is still lacking. Hence, the present review intends to highlight the current ecological scenario with respect to distribution, toxicity, degradation, various remediation technologies, and the regulatory aspects concerning cephalosporins. The latest successful technologies for cephalosporin degradation/removal discussed in this review will help researchers for a better understanding of the nature and persistence of cephalosporins in the environment along with the risks associated with their existence. The research thrust discussed in this review will also evoke new technologies to be attempted by the future researchers to develop sustainable options to remediate cephalosporin-contaminated environments.

Construction of a Quantitative Structure Activity Relationship (QSAR) Model to Predict the Absorption of Cephalosporins in Zebrafish for Toxicity Study

Cephalosporins are beta-lactam antibiotics that are widely used in China. Five generations of cephalosporins have been introduced in clinical practice to date; moreover, some new candidates are also undergoing clinical evaluations. To improve the success rates of new drug development, we need to have a comprehensive understanding about the relationship between the structure of cephalosporins and the toxicity that it induces at an early stage. In the cephalosporins toxicity study using zebrafish, the drug absorption is a key point. In this study, we determined the absorption of cephalosporins in zebrafish during toxicity test. The internal concentrations of 19 cephalosporins in zebrafish were determined using a developed liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Furthermore, a quantitative structure-activity relationship (QSAR) model was established by multilinear regression; moreover, it was used to predict the absorption of cephalosporins in zebrafish. During leave-one-out cross-validation, a satisfactory performance was obtained with a predictive ability (q ²) of 0.839. The prediction ability of the model was further confirmed when the predictive ability (q ²) was 0.859 in external prediction. The best QSAR model, which was based on five molecular descriptors, exhibited a promising predictive performance and robustness. In experiments involving drug toxicity, the developed QSAR model was used to estimate internal concentrations of cephalosporins. Thus, the toxicity results were correlated with the internal concentration of the drug within the larvae. The developed model served as a new powerful tool in zebrafish toxicity tests.

The zebrafish model of tuberculosis - no lungs needed

Tuberculosis is still a global health burden. It is caused by Mycobacterium tuberculosis which afflicts around one third of the world's population and costs around 1.3 million people their lives every year. Bacillus Calmette-Guerin vaccine is inefficient to prevent overt infection. Additionally, the lengthy inconvenient course of treatment, along with the raising issue of antimicrobial resistance, result in incomplete eradication of this infectious disease. The lack of proper animal models that replicate the latent and active courses of human tuberculosis infection remains one of the main reasons behind the poor advancement in tuberculosis research. Danio rerio, commonly known as zebrafish, is catching more attention as an animal model in tuberculosis research field. This shift is based on the histological and pathological similarities between Mycobacterium marinum infection in zebrafish and Mycobacterium tuberculosis infection in humans. Being small, cheap, transparent, and easy to handle have added further advantages to the use of zebrafish model. Besides better understanding of the pathogenesis of tuberculosis, Mycobacterium marinum infected zebrafish model is useful for evaluating novel vaccines against human tuberculosis, high throughput small molecule screening, repurposing established drugs with possible antitubercular activity, and assessing novel antituberculars for hepatotoxicity.

Screening for osteogenic activity in extracts from Irish marine organisms: The potential of Ceramium pallidum

Extracts and compounds derived from marine organisms have reportedly shown some osteogenic potential. As such, these bioactives may aid in the treatment of musculoskeletal conditions such as osteoporosis; helping to address inefficacies with current treatment options. In this study, 72 fractions were tested for their in vitro osteogenic activity using a human foetal osteoblast (hFOB) cell line and bone marrow derived mesenchymal stem cells (MSCs), focusing on their cytotoxic, proliferative and differentiation effects. Extracts dissolved in dimethyl sulfoxide and ethanol showed no significant osteogenic potential. However, two extracts derived from powder residues (left over from original organic extractions) caused a significant promotion of MSC differentiation. Bioactivity from powder residues derived from the epiphytic red algae Ceramium pallidum is described in detail to highlight its treatment potential. In vitro, C. pallidum was shown to promote MSC differentiation and extracellular matrix mineralisation. In vivo, this extract caused a significant increase in opercular bone growth of zebrafish larvae and a significant increase in bone density of regenerated adult caudal fins. Our findings therefore show the importance of continued screening efforts, particularly of novel extract sources, and the presence of bioactive compounds in C. pallidum extract.

Zebrafish: Speeding Up the Cancer Drug Discovery Process

Zebrafish (Danio rerio) is an ideal in vivo model to study a wide variety of human cancer types. In this review, we provide a comprehensive overview of zebrafish in the cancer drug discovery process, from (i) approaches to induce malignant tumors, (ii) techniques to monitor cancer progression, and (iii) strategies for compound administration to (iv) a compilation of the 355 existing case studies showing the impact of zebrafish models on cancer drug discovery, which cover a broad scope of scenarios. Finally, based on the current state-of-the-art analysis, this review presents some highlights about future directions using zebrafish in cancer drug discovery and the potential of this model as a prognostic tool in prospective clinical studies. Cancer Res; 78(21); 6048-58. ©2018 AACR.

Dysbiosis and early mortality in zebrafish larvae exposed to subclinical concentrations of streptomycin

Exposure to low concentrations of antibiotics found in aquatic environments can increase susceptibility to infection in adult fish due to microbiome disruption. However, little is known regarding the effect of antibiotic pollution on fish larvae. Here, we show that exposure to streptomycin, a common antibiotic used in medicine and aquaculture, disrupts the normal composition of zebrafish larvae microbiomes, significantly reducing the microbial diversity found in the fish. Exposure to streptomycin also significantly increased early mortality among fish larvae, causing full mortality within a few days of exposure at 10 μg/mL. Finally, we found that subclinical concentrations of streptomycin also increased the abundance of class 1 integrons, an integrase-dependent genetic system associated to the horizontal transfer of antibiotic resistance genes, in the larvae microbiomes. These results suggest that even low concentrations of streptomycin associated with environmental pollution could impact fish populations and lead to the creation of antibiotic resistance reservoirs.

Motor neuron development in zebrafish is altered by brief (5-hr) exposures to THC (∆9-tetrahydrocannabinol) or CBD (cannabidiol) during gastrulation

Marijuana is one of the most commonly used illicit recreational drugs and is widely used for medicinal purposes. The psychoactive ingredient in marijuana is ∆⁹-tetrahydrocannabinol (∆⁹-THC), whereas the major non-psychoactive ingredient is cannabidiol (CBD). Here, we exposed zebrafish embryos to ∆⁹-THC or CBD for 5 hours during the critical stage of development known as gastrulation. Embryos were allowed to develop normally and were examined at 2 and 5 days post fertilization. THC and CBD treated embryos exhibited reduced heart rates, axial malformations and shorter trunks. Cannabinoid treatment altered synaptic activity at neuromuscular junctions (NMJs), and fluorescent labelling of primary and secondary motor neurons indicated a change in branching patterns and a reduction in the number of axonal branches in the trunk musculature. Furthermore, there were alterations in the α-bungarotoxin labelling of nicotinic acetylcholine receptors at NMJs. Locomotion studies show that larvae exposed to THC or CBD during gastrulation exhibited drastic reductions in the number of C-start escape responses to sound stimuli, but not to touch stimuli. Together these findings indicate that zebrafish embryos exposed to ∆⁹-THC or CBD during the brief but critical period of gastrulation exhibited alterations in heart rate, motor neuronal morphology, synaptic activity at the NMJ and locomotor responses to sound.

Red algal extracts from Plocamium lyngbyanum and Ceramium secundatum stimulate osteogenic activities in vitro and bone growth in zebrafish larvae

Through the current trend for bioprospecting, marine organisms - particularly algae - are becoming increasingly known for their osteogenic potential. Such organisms may provide novel treatment options for osteoporosis and other musculoskeletal conditions, helping to address their large healthcare burden and the limitations of current therapies. In this study, extracts from two red algae – Plocamium lyngbyanum and Ceramium secundatum – were tested in vitro and in vivo for their osteogenic potential. In vitro, the growth of human bone marrow stromal cells (hBMSCs) was significantly greater in the presence of the extracts, particularly with P. lyngbyanum treatment. Osteogenic differentiation was promoted more by C. secundatum (70 µg/ml), though P. lyngbyanum had greater in vitro mineralisation potential. Both species caused a marked and dose-dependent increase in the opercular bone area of zebrafish larvae. Our findings therefore indicate the presence of bioactive components in P. lyngbyanum and C. secundatum extracts, which can promote both in vitro and in vivo osteogenic activity.

Relationship Between Fluoroquinolone Structure and Neurotoxicity Revealed by Zebrafish Neurobehavior

Central nervous system side effects are one of the most frequently reported adverse reactions of fluoroquinolones (FQs). However, the mechanism is not fully understood. In this study, zebrafish ( Danio rerio) were used as a model system. We quantified neurobehavior by recording indicators with automated video-tracking and used liquid chromatography-tandem mass spectrometry to detect drug absorption in vivo. We studied embryotoxicity and effects on zebrafish locomotor activity of 17 typical FQs. In addition, we calculated the stable conformation of typical FQs in aqueous conditions. The relationships between structure, neurotoxicity, and embryotoxicity were analyzed. The results indicate: (1) The effects of FQs on zebrafish neurobehavior can be divided into four categories. Type I has no significant influence on locomotor activity. Type II suppresses locomotor activity. Type III inhibits at low concentration and stimulates at high concentration. Type IV stimulates and then suppresses (biphasic response). (2) Structural modifications of FQs can change toxicity properties in zebrafish. Cleavage of the C-7 piperazinyl structure decreases neurotoxicity but enhances embryotoxicity. The C-3 decarboxyl formation and 5-NH₂ derivatives might enhance embryotoxicity and neurotoxicity. (3) There are two toxic functional groups. The piperazinyl structure at position C-7 (toxic functional group I) can cause primary reactions which may be by the inhibition of γ-aminobutyric acid receptors, and the nucleus containing a carboxyl group at position 3 (toxic functional group II) might cause a reaction secondary to the effect of toxic functional group I and reverse its effects.

Neurobehavioral Effects of Cephalosporins: Assessment of Locomotors Activity, Motor and Sensory Development in Zebrafish

Most third- and fourth-generation cephalosporins, such as cefotaxime, cefmenoxime, cefepime, and cefpirome, contain an aminothiazoyl ring at the C-7 position. Drug impurity, which may be produced either during synthesis or upon degradation, can induce adverse effects. Various reports have indicated that neurotoxicity is a side effect of cephalosporin. In this study, we developed methods for assessing the free-swimming activities and behaviors in zebrafish larvae in response to continuous darkness and stimulation of light-to-dark photoperiod transition by chemical treatments. We also performed transcriptome analysis to identify differentially expressed genes (DEGs). Gene ontology analysis revealed that various processes related to nervous system development were significantly enriched by DEGs. We integrated 16 DEGs with protein–protein interaction networks and identified that neuroactive ligand–receptor interaction [e.g., λ-aminobutyric acid and glutamate receptor, metabotropic 1a (GRM1A)] pathway was regulated by the compounds. Our findings suggested that neurobehavioral effects mainly depend on the mother nucleus structure 7-aminocephalosporanic acid and the substitution at the C-3 position. In addition, gad2, or111-4, or126-3, grm1a, opn8c, or111-5, or113-2, and or118-3 may potentially be utilized as novel biomarkers for this class of cephalosporins, which causes neurotoxicity. This study provides neurological behavior, transcriptome, and docking information that could be used in further investigations of the structures and developmental neurotoxicity relationship of chemicals.

Embryo and Developmental Toxicity of Cefazolin Sodium Impurities in Zebrafish

Cefazolin sodium is an essential drug that is widely used in clinical therapy for certain infective diseases caused by bacteria. As drug impurities are considered to be one of the most important causes of drug safety issues, we studied embryotoxicity, cardiotoxicity, and neurotoxicity of nine cefazolin sodium impurities in zebrafish embryo and larvae for the objective control of impurity profiling. LC-MS/MS was employed to analyze the compound absorbance in vivo, and the structure-toxicity relationship was approached. Our results suggested that the structure of MMTD (2-mercapto-5-methyl-1, 3, 4-thiadiazole) is the main toxic functional group for embryo deformities; the 7-ACA (7-aminocephalosporanic acid) structure mainly affects motor nerve function; and both the MMTD and 7-ACA structures are responsible for cardiac effects. Impurity G (7-ACA) presented with the strongest toxicity; impurity A was most extensively absorbed to embryo and larvae; and impurity F (MMTD) exhibited the strongest apparent toxic effect; Therefore, impurities F and G should be monitored from the cefazolin sodium preparations.

Emerging pollutant treatments in wastewater: Cases of antibiotics and hormones

Because of the intensive use of pharmaceutical substances in human life, studies on the detection of these chemical compounds and their metabolites as pollutants in water bodies are continuously reported. Some pharmaceutical agents are associated with adverse effects to aquatic life, even at very low concentrations (ng L^-1 to μg L^-1). For instance, the presence of antibiotics and hormones has been associated with increasing proliferation of antibiotic resistant pathogens and feminization and masculinization of some aquatic organisms. Currently, new attempts are being made to minimize or fully remove these types of pollutants from aquatic systems to protect the environment and human health. In this regard, physicochemical and biological treatments are among the most promising technologies for the treatment of wastewater containing pharmaceutical pollutants. These treatments are green alternatives for the degradation of hazardous organic compounds into nontoxic by-products. Here, we review some of the physicochemical and biological treatment methods used for the removal of the most extensively used antibiotics and hormones. Enzymatic oxidation, photocatalysis and electrochemical oxidation are described in terms of the aforementioned pharmaceutically active compounds (PhACs). The use of membrane technologies to separate different groups of antibiotics and hormones prior to biologic or physicochemical treatment methods is also addressed.

Humanizing the zebrafish liver shifts drug metabolic profiles and improves pharmacokinetics of CYP3A4 substrates

Understanding and predicting whether new drug candidates will be safe in the clinic is a critical hurdle in pharmaceutical development, that relies in part on absorption, distribution, metabolism, excretion and toxicology studies in vivo. Zebrafish is a relatively new model system for drug metabolism and toxicity studies, offering whole organism screening coupled with small size and potential for high-throughput screening. Through toxicity and absorption analyses of a number of drugs, we find that zebrafish is generally predictive of drug toxicity, although assay outcomes are influenced by drug lipophilicity which alters drug uptake. In addition, liver microsome assays reveal specific differences in metabolism of compounds between human and zebrafish livers, likely resulting from the divergence of the cytochrome P450 superfamily between species. To reflect human metabolism more accurately, we generated a transgenic "humanized" zebrafish line that expresses the major human phase I detoxifying enzyme, CYP3A4, in the liver. Here, we show that this humanized line shows an elevated metabolism of CYP3A4-specific substrates compared to wild-type zebrafish. The generation of this first described humanized zebrafish liver suggests such approaches can enhance the accuracy of the zebrafish model for toxicity prediction.