Parental exposure to cadmium chloride causes developmental toxicity and thyroid endocrine disruption in zebrafish offspring

Parental (F0) exposure to Cadmium and Ketoprofen induces developmental deformities in offspring (F1): A transgenerational toxicity assessment in zebrafish model

In the aquatic environment, the primary pollutants of heavy metals and pharmaceuticals always occur in coexisting forms, and the research about combined impacts remains unclear, especially transgenerational effects. Cadmium (Cd) is a heavy metal that can damage the endocrine reproduction systems and cause thyroid dysfunction in fish. Meanwhile, ketoprofen (KPF) is a nonsteroidal anti-inflammatory drug (NSAID) that can cause neurobehavioral damage and physiological impairment. However, to our knowledge, the combined exposure of Cd and KPF in transgenerational studies has not been reported. In this investigation, sexually mature zebrafish were subjected to isolated exposure and combined exposure to Cd (10 μg/L) and KPF (10 and 100 μg/L) at environmentally relevant concentrations for 42 days. In this background, breeding capacity, chemical accumulation rate in gonads, and tissue morphologies are investigated in parental fish. This is followed by examining the malformation rate, inflammation rate, and gene transcription in the F1 offspring. Our results indicate that combined exposure of Cd and KPF to the parental fish could increase the chemical accumulation rate and tissue damage in the gonads of fish and significantly reduce the breeding ability. Furthermore, these negative impacts were transmitted to its produced F1 embryos, reflected by hatching rate, body deformities, and thyroid axis-related gene transcription. These findings provide further insights into the harm posed by Cd in the presence of KPF to the aquatic ecosystems.

Thyroid-gonadal hormonal interplay in zebrafish exposed to sodium perchlorate: Implications for reproductive health

Perchlorate, a widespread environmental contaminant originating from various industrial applications, agricultural practices, and natural sources, poses potential risks to ecosystems and human health. While previous studies have highlighted its influence on the thyroid endocrine system and its impact on gonadal maturation, reproduction, and sex hormone synthesis, the specific interplay between thyroid and steroid hormones, in this context, remains largely unexplored. Therefore, this study was undertaken to investigate the adverse effects and underlying mechanisms triggered by exposure to sodium perchlorate (SP) on reproductive endocrine activity in zebrafish. For 21 d, the fish were exposed to test SP concentrations (0, 3, 30, 300 mg/L), which were determined based on the exposure concentrations that induced various toxic effects in the fish, considering naturally occurring concentrations. Exposure to SP, except at 3 mg/L in males, significantly decreased the production of thyroid hormone (TH) in both female and male zebrafish. Moreover, gonadal steroid levels were markedly reduced in both sexes. The expression of hepatic vitellogenin (VTG) mRNA in female zebrafish was significantly decreased, whereas aromatase activity in male zebrafish was significantly elevated in the SP exposure groups. The reduced levels of THs and gonadal steroid hormones were strongly correlated. Abnormal responses to SP exposure led to reduced reproductive success in the 300 mg/L SP exposure group. These findings indicate that prolonged and continuous exposure to a specific concentration of SP may lead to long-term reproductive problems in zebrafish, primarily through hormonal imbalances and suppression of hepatic VTG mRNA expression.

Zebrafish as model organisms for toxicological evaluations in the field of food science

Food safety has long been an area of concern. The selection of stable and efficient model organisms is particularly important for food toxicology studies. Zebrafish (Danio rerio) are small model vertebrates, and 70% of human genes have at least one zebrafish ortholog. Zebrafish have advantages as model organisms due to their short life cycle, strong reproductive ability, easy rearing, and low cost. Zebrafish embryos have the advantage of being sensitive to the breeding environment and thus have been used as biosensors. Zebrafish and their embryos have been widely used for food toxicology assessments. This review provides a systematic and comprehensive summary of food toxicology studies using zebrafish as model organisms. First, we briefly introduce the multidimensional mechanisms and structure-activity relationship studies of food toxicological assessment. Second, we categorize these studies according to eight types of hazards in foods, including mycotoxins, pesticides, antibiotics, heavy metals, endocrine disruptors, food additives, nanoparticles, and other food-related ingredients. Finally, we list the applications of zebrafish in food toxicology studies in line with future research prospects, aiming to provide a valuable reference for researchers in the field of food science.

Effects of cadmium exposure during the breeding period on development and reproductive functions in rare minnow (Gobiocypris rarus)

Cadmium is a common reproductive toxin in aquatic systems. Cd exposure of fish species at high concentrations can severely affect the reproductive function of fish. However, the underlying toxicity of cadmium exposure at low concentrations on the reproductive function in parental fish remains unclear. To investigate the impacts of cadmium exposure on reproductive capability, eighty-one male and eighty-one female rare minnows (Gobiocypris rarus) were exposed to cadmium at 0 (control group), 5 and 10 μg/L for 28 days, and then transferred into clean water to pair spawn. The results showed that cadmium exposure at 5 or 10 μg/L for 28 days in rare minnows could reduce the success rates of pair spawning in parent rare minnows, lessen no-spawning activities, and prolong the time for first spawning. Furthermore, the mean egg production of the cadmium exposure group increased. The fertility rate of the control group was significantly higher than that of the 5 μg/L cadmium exposure group. Anatomical and histological data further revealed that the intensity of atretic vitellogenic follicles significantly increased and spermatozoa vacuolated after cadmium exposure (p < 0.05), but slightly increased the condition factor (CF), and relatively stable gonadosomatic index (GSI) values were also observed in the cadmium exposure groups. These observed results indicated that cadmium exposure at 5 or 10 μg/L affected the reproductive activity of paired rare minnow by accumulating Cd in the gonads, and the effect diminished over time. The reproductive risk of low-dose cadmium exposure to fish species remains a cause for concern.

Toxic Effects of Cadmium on Fish

Large amounts of enriched cadmium (Cd) in the environment seriously threatens the healthy and sustainable development of the aquaculture industry and greatly restricts the development of the food processing industry. Studying the distribution and toxic effects of Cd in fish, as well as the possible toxic effects of Cd on the human body, is very significant. A large number of studies have shown that the accumulation and distribution of Cd in fish are biologically specific, cause tissue differences, and seriously damage the integrity of tissue structure and function, the antioxidant defense system, the reproductive regulation system, and the immune system. The physiological, biochemical, enzyme, molecular, and gene expression levels change with different concentrations and times of Cd exposure, and these changes are closely related to the target sites of Cd action and tissues in fish. Therefore, the toxic effects of Cd on fish occur with multiple tissues, systems, and levels.

Environmental Co-Exposure to Potassium Perchlorate and Cd Caused Toxicity and Thyroid Endocrine Disruption in Zebrafish Embryos and Larvae (Danio rerio)

The increasing pollution of aquatic habitats with anthropogenic compounds has led to various test strategies to detect hazardous chemicals. However, information on the effects of pollutants on the thyroid system in fish, which is essential for growth, development, and parts of reproduction, is still scarce. Modified early life-stage tests were carried out with zebrafish exposed to the known thyroid inhibitor potassium perchlorate (0.1, 1, 1.5, 2, 2.5, and 5 mM) to identify adverse effects on embryo development. The endogenous antioxidant defense mechanism is one of the key functions of the thyroid gland; in this regard, we examined the co-exposure to potassium perchlorate (KClO₄), which could disrupt thyroid function, with cadmium (Cd), a known pro-oxidant compound. Zebrafish embryos were exposed to control KClO₄ 1 mM and Cd 0.5 μM for 96 h after fertilization (hpf) individually and in combination. The morphological alteration, body length, and messenger RNA (mRNA) expression related to thyroid function and oxidative stress, thyroid hormone levels, and malondialdehyde were measured. Significant down-regulation of mRNAs related to thyroid function (thyroid hormone receptor-alpha (THRα), thyroid hormone receptor-beta (THRβ), haematopoietically expressed homeobox (hhex)) and decreased thyroxin (T4) levels were observed after co-exposure to KClO₄ and Cd, but this was not observed in the individually treated groups. These results suggest that co-exposure to KClO₄ and Cd could affect antioxidant defense mechanisms and potentially normally increase Cd toxicity on mRNA expression, altering the thyroid functions important in zebrafish embryonic developmental stages.

Xianling Gubao Capsule Prevents Cadmium-Induced Kidney Injury

Xianling Gubao Capsule (XGC), a kind of capsule preparation of Chinese herbal officially approved for sale by the National Medical Products Administration (NMPA), has the effect of tonifying kidney and strengthening bones. Although the impact of XGC in treating bone diseases has been widely studied, the effect of XGC in kidney injury is unknown yet. The kidney injury model is established by intraperitoneal injection with cadmium chloride (CdCl2). Before model establishment, each XGC group was pregavaged with XGC for 10 d. After 10 d, CdCl2 was injected intraperitoneally into the model group and each XGC group, each XGC group continued to be gavaged with XGC for 4 weeks, and the control group was gavaged with equal doses of distilled water once daily. The level of serum urea nitrogen (BUN) and serum creatinine (Cr) is evaluated by kit. The effect of XGC on protecting kidney injury in mice with kidney injury is analyzed by histopathology (HE stain), immunohistochemistry (IHC), and real-time fluorescence quantitative PCR (RT-qPCR). The results show that CdCl2 significantly increases the level BUN and Cr in serum and results in remarkable pathological changes in the nephron, including tubule edema, congestion, and necrosis. While oral administration of XGC can significantly decrease BUN and Cr in serum and prevent and protect the kidney from the above injuries. In addition, the protein expression of p-mTOR was remarkably reduced, and the ratio of LC3II/LC3I protein and mRNA was significantly increased in mice with oral administration of XGC. Our findings suggest that XGC can prevent and protect kidney injury by improving the state of renal tubular hyperemia and necrosis and reduce the level of BUN and Cr in cadmium poisoning mice.

Cadmium exposure induces inflammation and necroptosis in porcine adrenal gland via activating NF-κB/MAPK pathway

Cadmium (Cd) is a heavy metal harmful to animals and humans. Cd exposure causes inflammation or necroptosis in many tissues, including adrenal tissue. However, the current researches on the effects of Cd²⁺ in adrenal tissues are not enough. Therefore, in our experiment Cd chloride (CdCl₂) was added to the piglet's diet at a concentration of 20 mg/kg to study the effects of Cd²⁺ exposure on the porcine adrenal tissue. Our results showed that Cd²⁺ exposure could cause inflammation by activating the nuclear factor kappa-B (NF-κB) pathway, which in turn induced necroptosis in adrenal tissue with the activated mitogen-activated protein kinase (MAPK) pathway. The expression increase of inflammatory factors and necroptosis downstream genes, and the downregualtion of cysteinyl aspartate specific proteinase 8 (Caspase 8) proved that Cd²⁺ exposure caused inflammation and necroptosis in adrenal tissue. We conclude that this report provides more basic theoretical data for exploring the mechanism of adrenal injury.

Thyroid disrupting effects of low-dose dibenzothiophene and cadmium in single or concurrent exposure: New evidence from a translational zebrafish model

Thyroid hormones (THs) are major regulators of biological processes essential for correct development and energy homeostasis. Although thyroid disruptors can deeply affect human health, the impact of exogenous chemicals and in particular mixture of chemicals on different aspects of thyroid development and metabolism is not yet fully understood. In this study we have used the highly versatile zebrafish model to assess the thyroid axis disrupting effects of cadmium (Cd) and dibenzothiophene (DBT), two environmental endocrine disruptors found to be significantly correlated in epidemiological co-exposure studies. Zebrafish embryos (5hpf) were exposed to low concentrations of Cd (from 0.05 to 2 μM) and DBT (from 0.05 to 1 μM) and to mixtures of them. A multilevel assessment of the pollutant effects has been obtained by combining in vivo morphological analyses allowed by the use of transgenic fluorescent lines with liquid chromatography mass spectrometry determination of TH levels and quantification of the expression levels of key genes involved in the Hypothalamic-Pituitary-Thyroid Axis (HPTA) and TH metabolism. Our results underscore for the first time an important synergistic toxic effect of these pollutants on embryonic development and thyroid morphology highlighting differences in the mechanisms through which they can adversely impact on multiple physiological processes of the HPTA and TH disposal influencing also heart geometry and function.

Study on toxicological effect and the mechanism of cadmium in rice and inorganic cadmium on ICR mice

Cadmium (Cd) exposure may induce chronic intoxication, but the harm of cadmium in rice to human at chronic low-level Cd exposure remains unclear. This study employed a mouse model to investigate the toxicity and mechanism of cadmium in rice and CdCl2. After 8-week exposure to Cd (CdCl2 and Cd-contaminated rice), the biochemical indicators and oxidation indicators in the serum and liver of mice were determined, and used mRNA sequencing to investigate the mechanism of different forms of Cd. Results showed that the cadmium concentration of the liver in the CdCl2 + Rice-N group (CdCl2 mixed with feed and normal rice, 0.4mg/kg.bw) was higher than that in the Rice-H group (0.4mg/kg.bw). However, the cadmium concentration of the kidneys in the Rice-H group was higher than that in the CdCl2 + Rice-N group. Our study demonstrated that Cd-treated (Cd in rice and CdCl2) ICR mice generated obviously tissues injury, such as the increased biochemical studies, the activity of antioxidant enzymes debasement. Simultaneously, our data also indicated that there existed difference of the hepatic toxicity between Cd in rice and CdCl2. By means of transcriptomics, we discovered that CdCl2 and Cd in rice may affect different gene expression at the molecular level. We hope to provide some theoretical basis for the revision of food security standards.

In vivo visualization assay to evaluate the effects of maternal exposure to mercury on offspring bioaccumulation in the oriental river prawn (Macrobrachium nipponense)

Mercury (Hg) is a persistent pollutant that accumulates in aquatic animals. However, studies related to understand how gonad tissue of this species responds to mercury exposure and elucidation of mercury bioaccumulation in crustacean offspring by cross-generational, are still sparse. The present study aimed to assess the bioaccumulation of Hg²⁺in vivo in prawn offspring by a specific aggregation-induced emission fluorogen (AIEgen). The 96 h median lethal concentration (LC₅₀) values of mercury to the juveniles were 0.072 mg/L. Hg²⁺ reduced growth performance, damaged oocyte quality, and inhibited ovary maturation, thus inhibiting gonadal maturation in intact prawns. F1 offspring were exposed to Hg²⁺ by direct transfer from their F0 parents, as shown by the distribution of mercury in gonads and fertilized eggs. In the medium containing oriental river prawn larvae, the Hg²⁺ concentration decreased rapidly, indicating fast initial larval uptake of Hg²⁺. Due to metal ion triggered AIE activity, analysis of fluorescence images showed that prawn offspring accumulated Hg²⁺ via maternal transfer, and there was a relationship among the photoluminescence intensity, the AIEgen concentration, and mercury levels. The quantitative detection of Hg²⁺ absorption from prawn larvae by the AIEgen represents a novel analytical technique to understand the dynamics of Hg²⁺ between maternal and offspring.

Metabolomics analysis of the effects of quercetin on renal toxicity induced by cadmium exposure in rats

This study aims to explore the protective effects of quercetin against cadmium-induced nephrotoxicity utilizing metabolomics methods. Male Sprague-Dawley rats were randomly assigned to six groups: control, different dosages of quercetin (10 and 50 mg/kg·bw, respectively), CdCl2 (4.89 mg/kg·bw) and different dosages quercetin plus CdCl2 groups. After 12 weeks, the kidneys were collected for metabolomics analysis and histopathology examination. In total, 11 metabolites were confirmed, the intensities of which significantly changed (up-regulated or down-regulated) compared with the control group (p < 0.00067). These metabolites include xanthosine, uric acid (UA), guanidinosuccinic acid (GSA), hypoxanthine (Hyp), 12-hydroxyeicosatetraenoic acid (tetranor 12-HETE), taurocholic acid (TCA), hydroxyphenylacetylglycine (HPAG), deoxyinosine (DI), ATP, formiminoglutamic acid (FIGLU) and arachidonic acid (AA). When high-dose quercetin and cadmium were given to rats concurrently, the intensities of above metabolites significantly restored (p < 0.0033 or p < 0.00067). The results showed quercetin attenuated Cd-induced nephrotoxicity by regulating the metabolism of lipids, amino acids, and purine, inhibiting oxidative stress, and protecting kidney functions.