Sublethal psychotropic pharmaceutical effects on the model organism Danio rerio: Oxidative stress and metal dishomeostasis

Acute exposure to environmentally relevant concentrations of pharmaceutical pollutants induces neurobehavioral toxicity in zebrafish (Danio rerio)

Pharmaceutical waste from point and non-point sources enters, persists, or disseminates in the environment and is known as environmentally persistent pharmaceutical pollutants. Understanding the impacts of pharmaceutical pollutants on the environment and health is essential. This study investigates the behavioral impacts of pharmaceutical pollutants on aquatic organisms and delineates the possible nexus of oxidative stress. The male zebrafish were exposed to four major representative pharmaceutical pollutants, viz., acetaminophen, carbamazepine, metformin, and trimethoprim at environmentally relevant concentrations individually as well as in a mixture for seven days. Substantial alterations in social interaction, aggressive nature, novel tank exploration, and light and dark zone preferences were recorded and the degree varied to different pharmaceutical pollutants. The activity of oxidative stress markers, superoxide dismutase, glutathione-S-transferase, and catalase, was found to be suppressed to 66-20%, 42-25%, and 59-20% respectively with the elevated malondialdehyde generation (180-260%) compared to control. The activity level of acetylcholine esterase was found to be increased to 200-500% across all treatment groups. Despite the synergistic impacts of pharmaceutical pollutants on the whole system that could not be ascertained, this comprehensive study highlights their toxicity nature to induce neurobehavioral toxicity in zebrafish through oxidative stress mechanisms and altered cholinergic systems.

Antioxidant system alterations, oxidative, and genotoxic effects in Danio rerio (zebrafish) exposed to leachate from a dumpsite

Water body contamination by leachate originated from dumpsites is a concern for municipal solid waste (MSW) management. In this context, this study aimed to evaluate antioxidant system alterations and oxidative and genotoxic effects in Danio rerio (zebrafish) exposed to leachate from a closed dumpsite. Groups comprising 50 fish were exposed (96 h) to different leachate concentrations (5, 15, 30, and 50%) to evaluate effects on liver and brain superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST) activities and reduced glutathione (GSH) and metallothionein (MT) concentrations, as well as malondialdehyde (MDA) and protein carbonylation (PTC) levels. Blood genotoxicity was evaluated by the comet assay. The investigated dumpsite leachate pond presented high chloride concentrations (Cl-; 2288.4 ± 69.5 mg L-1) and high electrical conductivity (EC; 8434.0 mS cm-1), indicating the presence of leachate. Concerning Danio rerio exposure, higher SOD (37%), CAT (67%), and GST (39%) activities and higher GSH (57%) concentrations were observed in liver following exposure to 50% leachate, while decreased brain GST (42%) activities and GSH (90%) levels were observed at the same leachate concentration. A significant increase in the olive tail moment (OTM; 280%) indicative of genotoxicity in blood was observed. A principal component analysis indicated that increased enzymatic activities and high levels of both GSH and MT were not sufficient to prevent the accumulation of reactive oxygen species, resulting in PTC and genotoxicity. Therefore, leachate exposure causes sublethal Danio rerio effects, altering the antioxidant system, increasing ROS production, and leading to PTC and genotoxicity. The findings demonstrate the need to further develop sublethal level assessments in zebrafish using leachate from different sources to subsidize risk assessments regarding MSW management.

The occurrence of typical psychotropic drugs in the aquatic environments and their potential toxicity to aquatic organisms - A review

Psychotropic drugs (PDs) and their bioactive metabolites often persist in aquatic environments due to their typical physical properties, which made them resistant to removal by traditional wastewater treatment plants (WWTPs). Consequently, such drugs and/or their metabolites are frequently detected in both aquatic environments and organisms. Even at low concentrations, these drugs can exhibit toxic effects on non-target organisms including bony fish (zebrafish (Danio rerio) and fathead minnows) and bivalves (freshwater mussels and clams). This narrative review focuses on the quintessential representatives of three different categories of PDs-antiepileptics, antidepressants, and antipsychotics. The data regarding their concentrations occurring in the environment, patterns of distribution, the degree of enrichment in various tissues of aquatic organisms, and the toxicological effects on them are summarized. The toxicological assessments of these drugs included the evaluation of their effects on the reproductive, embryonic development, oxidative stress-related, neurobehavioral, and genetic functions in various experimental models. However, the mechanisms underlying the toxicity of PDs to aquatic organisms and their potential health risks to humans remain unclear. Most studies have focused on the effects caused by acute short-term exposure due to limitations in the experimental conditions, thus making it necessary to investigate the chronic toxic effects at concentrations that are in coherence with those occurring in the environment. Additionally, this review aims to raise awareness and stimulate further research efforts by highlighting the gaps in the understanding of the mechanisms behind PD-induced toxicity and potential health risks. Ultimately, the study underscores the importance of developing advanced remediation methods for the removal of PDs in WWTPs and encourages a broader discussion on mitigating their environmental impacts.

Effects of common antiepileptic drugs on teleost fishes

Antiepileptic drugs (AEDs) are globally prescribed to treat epilepsy and many other psychiatric disorders in humans. Their high consumption, low metabolic rate in the human body and low efficiency of wastewater treatment plants (WWTPs) in eliminating these chemicals results in the frequent occurrence of these pharmaceutical drugs in aquatic systems. Therefore, aquatic organisms, including ecologically and economically important teleost fishes, may be inadvertently exposed to these chemicals. Due to their physiological similarity with humans, fishes may be particularly vulnerable to AEDs. Almost all AED drugs are detectable in natural aquatic ecosystems, but diazepam (DZP) and carbamazepine (CBZ) are among the most widely detected AEDs to date. Recent studies suggest that these drugs have a substantial capacity to induce neurotoxicity and behavioral abnormality in fishes. Here we review the current state of knowledge regarding the potential mode of action of DZP and CBZ as well as that of some other AEDs on teleosts and put observable behavioral effects into a mechanistic context. We find that following their intended mode of action in humans, AEDs also disrupt the GABAergic, glutamatergic and serotonergic systems as well as parasympathetic neurotransmitters in fishes. Moreover, AEDs have non-specific modes of action in teleosts ranging from estrogenic activity to oxidative stress. These physiological changes are often accompanied by dose-dependent disruptions of anxiety, locomotor activity, social behaviors, food uptake, and learning and memory, but DZP and CBZ consistently induced anxiolytic effects. Thereby, AED exposure severely compromises individual fitness across teleost fish species, which may lead to population and ecosystem impairment. We also showcase promising avenues for future research by highlighting where we lack data when it comes to effects of certain AEDs, AED concentrations and behavioral endpoints.

Clotrimazole is effective, safe and tolerable for the treatment of endometriosis and functions by downregulating inducible nitric oxide synthase and modulating oxidative stress biomarkers

This study investigated the mechanism of action of clotrimazole (CTZ) and its adverse effects in a model of endometriosis. After autologous endometrial implantation, 18 rats were randomized into two treatment groups: 200 mg/kg CTZ or vehicle for 15 consecutive days. The lesion growth, implant size, glandular atrophy, nitric oxide (NO) serum levels, number of macrophage cells and inducible nitric oxide synthase (iNOS) immunoreactivity were significantly reduced in the CTZ group compared with the control. CTZ (p < 0.05) reduced the lipid peroxidation and protein carbonylation levels in the liver but did not alter the superoxide dismutase (SOD), glutathione (GSH) or glutathione S-transferase (GST) levels in the brain; however, the drug significantly reduced SOD activity and enhanced GST activity in the liver. These results suggest that CTZ interferes with reactive nitrogen species production by downregulating iNOS expression and thus enhances the antioxidant system to promote atrophy and regression of endometriotic lesions, without adverse effects on the brain and/or liver.

Oxidative stress and metal homeostasis alterations in Danio rerio (zebrafish) under single and combined carbamazepine, acetamiprid and cadmium exposures

Contaminants of emerging concern (CEC) are routinely detected in aquatic environments, especially pharmaceuticals, such as carbamazepine (CBZ), and neonicotinoid pesticides, like acetamiprid (ACT). CECs can interact with each other and with other legislated contaminants like Cd, resulting in unknown effects. Most studies evaluate only the effects of single contaminant exposures on aquatic biota. Therefore, the aim of the present study was to assess the effects of both single and combined CBZ, ACT and Cd exposures on zebrafish brain and liver oxidative stress parameters and metal homeostasis. The biomarkers catalase (CAT), glutathione-S-transferase (GST), total thiols (TOT), metallothionein (MT) and malondialdehyde (MDA) and the essential elements Ca, Cu, K, Na, Mg, Mn and Zn were evaluated after 96-hour static exposures. CBZ, ACT and Cd single (brain and liver) and combined (liver) treatments resulted in oxidative effects in both fish organs, also leading to metal (Ca, Mg, K, Mn, Zn and Cu) homeostasis alterations. ACT exposure resulted in the greatest adverse effects in the brain, while CBZ was the cause of major element homeostasis and oxidative stress alterations in the liver. Lower LPO levels were observed in the combined treatments compared to single treatments, suggesting interactions and contaminant effect attenuation. This study is the first to evaluate the initial effects of combined CBZ, ACT and Cd exposures in zebrafish, paving the way for further investigations concerning other biomarkers during longer exposure times.

Effects of carbamazepine in aquatic biota

Carbamazepine (CBZ) is one of the most common pharmaceuticals found in the aquatic environment. Here, we reviewed studies in aquatic animals highlighting that CBZ affected ROS homeostasis but also the neuroendocrine system, cell viability, immunity, reproduction, feeding behavior and growth. Notably, the acetylcholinesterase activity was modified by concentrations of the order of ng L^-1 CBZ. At ≥10 μg L^-1, data pointed that CBZ triggered the production of ROS, modifying the activity of antioxidant enzymes and produced a significant cellular stress at concentrations ≥100 μg L^-1. However, the response appeared species-, organ- and time-dependent, and was impacted by different experimental conditions and the origin of animals. In this context, this review discusses the available data and proposes future research priorities.

Human Drug Pollution in the Aquatic System: The Biochemical Responses of Danio rerio Adults

Simple Summary

The release of medicinal products for human use in the aquatic environment is now a serious problem, and can be fatal for the organisms that live there. Danio rerio is a freshwater fish that provides the possibility to study the effects of these pollutants on the health of aquatic organisms. The results of the various existing scientific studies are scarce and conflicting. Here, we review the scientific studies that have analyzed these effects, highlighting that the impacts of drugs are evident in the biochemical responses of these animals.

Abstract

To date, drug pollution in aquatic systems is an urgent issue, and Danio rerio is a model organism to study the toxicological effects of environmental pollutants. The scientific literature has analyzed the effect of human drug pollution on the biochemical responses in the tissues of D. rerio adults. However, the information is still scarce and conflicting, making it difficult to understand its real impact. The scientific studies are not consistent with each other and, until now, no one has grouped their results to create a baseline of knowledge of the possible impacts. In this review, the analysis of literature data highlights that the effects of drugs on adult zebrafishes depend on various factors, such as the tissue analyzed, the drug concentration and the sex of the individuals. Furthermore, the most influenced biochemical responses concern enzymes (e.g., antioxidants and hydrolase enzymes) and total protein and hormonal levels. Pinpointing the situation to date would improve the understanding of the chronic effects of human drug pollution, helping both to reduce it in the aquatic systems and then to draw up regulations to control this type of pollution.

Dietary supplementation with increasing doses of an organic micromineral complex on juvenile Nile tilapia: Effects on the antioxidant defense system and tissue deposition

The effect of increasing amounts (0%, 25%, 50%, 75%, and 100%) of dietary supplementation with an organic micromineral complex (Fe, Zn, Cu, Mn, and Se) on antioxidant defenses and mineral deposition in tissues of Nile tilapia juveniles was evaluated, where 100% supplementation represented the average adopted by the feed industry in Brazil. Fish (initial weight 23.93 ± 0.80 g) were fed until apparent satiation twice a day for 56 days. The maximum deposition of Fe and Zn in the hepatopancreas occurred in fish given approximately 50% supplementation, whereas the deposition of Mn and Se increased linearly with the inclusion of the complex. The activity of catalase and superoxide dismutase in the hepatopancreas decreased in fish fed the 50% dose, when compared to those not receiving mineral supplementation or those receiving higher doses. Glutathione peroxidase (GPx) activity in the hepatopancreas increased as the dietary Se concentration increased. However, the concentration of metallothionein in the hepatopancreas showed an inverse relationship to the increase in dietary supplementation of the organic mineral complex. There was no relationship between the doses of organic micromineral supplementation and the activities of GPx, reduced glutathione, non-protein thiols, or protein carbonylation. However, diets supplemented with 50% to 100% promoted greater GPx activity when compared to the 0% supplemented diet. Supplementation with intermediate doses of organic microminerals, approximately 50% of that used in commercial tilapia diets, promoted the homeostasis of metal metabolism, especially for Fe and Zn.

Electrochemical degradation of psychotropic pharmaceutical compounds from municipal wastewater and neurotoxicity evaluations

Contaminants of emerging concern (CECs) are released daily into surface water, and their recalcitrant properties often require tertiary treatment. Electrochemical oxidation (EO) is often used as an alternative way to eliminate these compounds from water, although the literature barely addresses the neurotoxic effects of residual by-products. Therefore, this study investigated the performance of EO in the removal of five CECs (alprazolam, clonazepam, diazepam, lorazepam, and carbamazepine) and performed neurotoxicity evaluations of residual EO by-products in Wistar rat brain hippocampal slices. Platinum-coated titanium (Ti/Pt) and boron-doped diamond (BDD) electrodes were studied as anodes. Different current densities (13-75 A m^-2), pH values (3-10), electrolyte dosages (NaCl), and matrix effects were assessed using municipal wastewater (MWW). The drugs were successfully degraded after 5 min of reaction for both the Ti/Pt and BDD electrodes when a current density of 75 A m^-2 was applied. For Ti/Pt and BDD, neutral and acidic pH demonstrated better CEC removal performance, respectively. Compound degradation using MWW achieved 40% removal after 120 min for Ti/Pt and ranged between 33 and 52% for the BDD anode. For Ti/Pt, neurotoxicity studies using MWW indicated a decrease in reactive oxygen species (ROS) signals. However, when an artificial cerebrospinal fluid (ACSF) medium was reapplied, the signal recovered and increased to a value above the baseline, indicating that cells recovered part of their normal activity but remained in a different condition. For the BDD anode, the treated MWW did not cause significant ROS production variations, suggesting that he EO was effective in eliminating the toxicity of the treated solution.

Evaluation of the potential environmental risk from the destination of medicines: an epidemiological and toxicological study

BACKGROUND

The high consumption of medicines by the population and their storage at home might cause an increase in the number of pharmaceutical substances that may be inappropriately discarded in the sanitary sewage, reaching an environmental aquatic. Thus, the effects of these emerging contaminants need more studies.

OBJECTIVES

To identify the profile of most medicines that are discarded by users of community pharmacy and evaluate the toxicity of the most disposed drugs.

METHODS

This was a translational study. A descriptive observational study was carried out for convenience of community pharmacy users using a standardized questionnaire. Subsequently, the lethal concentration 50 (LC₅₀) for medicine that is most frequently discarded was determined. After LC_50, the embryos (n = 144) were exposed to sublethal concentrations for most discarded drug at 24, 48, and 72 h. Mortality, heartbeat, and embryo deformities were used as parameters of toxicity.

RESULTS

Most respondents (96%) had a "home pharmacy." The primary forms of disposal were in the common household waste, kitchen sink, and/or bathroom. The medicines that were most incorrectly discarded by the interviewees were nimesulide (17.1%), dipyrone (10.7%), and paracetamol (5.2%). LC₅₀ of nimesulide was calculated (0.92 μgmL^-1). The toxicological test revealed that embryos exposed to nimesulide showed several abnormalities, such as defects in the spinal cord, tail, yolk sac, as well as pericardial edema. Furthermore, the heartbeat decreased by 30% at a concentration of 0.4 μgmL^-1 as compared with control group. The yolk sac and pericardial areas increased to >100% in all treatment groups when compared with the control group.

CONCLUSION

Respondents disposed medicines in an inappropriate manner primarily in household waste and in the toilet. Nimesulide was the most discarded drug according to study population. Moreover, teratogenic effects such as spinal cord defects, decreasing heartbeats, and increasing pericardial and yolk sac area in embryos were observed after exposure to nimesulide. These results show that nimesulide may promote risk to aquatic organisms and to human health if it is discarded in an unsafe manner.

Single and combined effects of carbamazepine and copper on nervous and antioxidant systems of zebrafish (Danio rerio)

Various pollutants co-exist in the aquatic environment such as carbamazepine (CBZ) and copper (Cu), which can cause complex effects on inhabiting organisms. The toxic impacts of the single substance have been studied extensively. However, the studies about their combined adverse impacts are not enough. In the present study, zebrafish were exposed to environmental relevant concentrations of CBZ (1, 10, and 100 μg/L), Cu (0.5, 5, and 10 μg/L) and the mixtures (1 μg/L CBZ + 0.5 μg/L Cu, 10 μg/L CBZ + 5 μg/L Cu, 100 μg/L CBZ + 10 μg/L Cu) for 45 days, the effects on nervous and antioxidant systems of zebrafish were investigated. The results demonstrated that, in comparison with single exposure group, the combined presence of CBZ and Cu exacerbated the effect of antioxidant system (the ability of inhibition of hydroxyl radicals (IHR), superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST)) but not nervous system (Acetylcholinesterase [AChE]). The qPCR results supported the changes of corresponding enzymes activities. Hepatic histopathological analysis verified the results of biomarkers. Our work illustrated that the toxicity of mixed pollutants is very complicated, which cannot simply be inferred from the toxicity of single pollutant, and calls for more co-exposure experiments to better understanding of the co-effects of pollutants on aquatic organisms.

Genotoxicity and oxidative damage in zebrafish (Danio rerio) after exposure to effluent from ethyl alcohol industry

In this research, the toxicological effect of untreated wastewater from of ethyl alcohol industry was evaluated on the zebrafish (Danio rerio) under experimental conditions. Fish were treated with zero, half, one and two percent of sewage effluent for 21 days. Toxic effects were monitored in liver by determining biochemical indicators, oxidative stress biomarkers, and the expression of genes involved in the detoxification. Results showed that Sod1, Gstp-1a, Gpx1a gene expressions were significantly increased in the hepatocytes after 21 days at 2.0% sewage exposure. Sewage exposure also significantly increased Gsr, Ces2 and Cyp1a, Mt1 and Mt2 gene expression in the hepatocytes of zebrafish as compared to the reference group (P < 0.01). Total cellular antioxidants, malondialdehyde (MDA) levels, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and alkaline phosphatase (ALP) activities in fish exposed to 1 and 2% of sewage were significantly higher than the control group (P < 0.01), whereas alanine aminotransferase (ALT) was only increased in fish exposed to 2% sewage (P < 0.01). A significant decrease in gamma-glutamyl-transferase (GGT) activity in fish exposed to 2% effluent was found (P < 0.01). Catalase (CAT) activity was increased in zebrafish exposed to all concentrations of effluent. The transcriptional analysis of the detoxification-related genes and the changes in the biochemical indicators evidenced that drainage of sewage effluents from the ethyl alcohol company is a serious threat to the health of aquatic animals in the Khorram-Rood River. These results will contribute to further study on the impact of sewage effluents of the alcohol industry on aquatic organisms.

Use of Zebrafish in Drug Discovery Toxicology

Unpredicted human safety events in clinical trials for new drugs are costly in terms of human health and money. The drug discovery industry attempts to minimize those events with diligent preclinical safety testing. Current standard practices are good at preventing toxic compounds from being tested in the clinic; however, false negative preclinical toxicity results are still a reality. Continual improvement must be pursued in the preclinical realm. Higher-quality therapies can be brought forward with more information about potential toxicities and associated mechanisms. The zebrafish model is a bridge between in vitro assays and mammalian in vivo studies. This model is powerful in its breadth of application and tractability for research. In the past two decades, our understanding of disease biology and drug toxicity has grown significantly owing to thousands of studies on this tiny vertebrate. This Review summarizes challenges and strengths of the model, discusses the 3Rs value that it can deliver, highlights translatable and untranslatable biology, and brings together reports from recent studies with zebrafish focusing on new drug discovery toxicology.

Lethal and sublethal effects of acetamiprid on Eisenia andrei: Behavior, reproduction, cytotoxicity and oxidative stress

The neonicotinoid acetamiprid has been suggested as a worldwide substitute for organophosphates, due to its lower toxicity. The present study assessed several acetamiprid effects on Eisenia andrei earthworms in acute contact (ranging from 1.6 × 10^-5 to 0.16 μg cm^-2 acetamiprid), behavioral (0.1, 0.5, 1 mg kg^-1) and chronic (0.001, 0.01, 0.05 and 0.1 mg kg^-1 acetamiprid) assays carried out in natural soil. Reproduction, cytotoxicity (coelomocyte density and viability), immune cell typing (eleocytes and amoebocytes) and antioxidant defense system (glutathione (GSH), catalase (CAT) and glutathione S-transferase (GST)) responses were determined. The LC₅₀ in the acute contact test was calculated as 1.86 × 10^-2 μg cm^-2. Acetamiprid concentrations of 0.5 and 1 mg kg^-1 led to earthworm avoidance responses (NR = 61.09 ± 10.01%) and habitat loss (NR = 78.02 ± 12.03%), respectively. Reproduction was also affected, with a decreased number of cocoons and hatchlings per cocoon observed at 0.05 and 0.1 mg kg^-1. Amoebocytes were the predominant immune system cells during the 15th and 30th assay days, while eleocytes were the main cells observed at the 45th day. CAT activities on the 30th and 45th day of exposure were increased at the lowest acetamiprid concentrations (0.001 and 0.01 mg kg^-1) and decreased with increasing pesticide concentration (0.05 and 0.1 mg kg^-1). Maximum GST activities and GSH levels were noted at 0.01 mg kg^-1 acetamiprid. However, increasing concentrations led to GST inhibition, while GSH levels were maintained. A long-term acetamiprid exposure affected earthworm reproduction, behavior and immune and antioxidant systems, which could affect the ecological soil balance and, consequently, the entire food chain.