Mode of action of human pharmaceuticals in fish: the effects of the 5-alpha-reductase inhibitor, dutasteride, on reproduction as a case study

Bioconcentration of pharmaceuticals by aquatic flora in an Australian river system

Pharmaceuticals are emerging contaminants in the environment and are a ubiquitous presence in rivers downstream of wastewater treatment plant outfalls. Questions remain about the persistence of pharmaceuticals in rivers, and the uptake and bioconcentration of pharmaceuticals by aquatic plants. Our study took place in the Yarrowee/Leigh/Barwon River system in southeastern Australia. We quantified the concentrations of five pharmaceuticals (carbamazepine, primidone, propranolol, tramadol, and venlafaxine) in surface water at five sites along a 144-km stretch of river, downstream of the presumed primary point source (a wastewater treatment plant outfall). We quantified pharmaceuticals in the leaves of two aquatic plant species (Phragmites australis and Vallisneria australis) sampled at each site, and calculated bioconcentration factors. All five pharmaceuticals were detected in surface waters, and the highest detected concentration exceeded 500 ng.L-1 (tramadol). Four of the pharmaceuticals (all except tramadol) were detected and quantified at all sites, including the furthest site from the outfall (144 km). Carbamazepine showed less attenuation with distance from the outfall than the other pharmaceuticals. Carbamazepine and venlafaxine were quantified in the leaves of both aquatic plant species (range: 10-31 ng.g-1), and there was evidence that bioconcentration factors increased with decreasing surface water concentrations. The study demonstrates the potential long-distance persistence of pharmaceuticals in river systems, and the bioconcentration of pharmaceuticals by aquatic plants in natural ecosystems. These phenomena deserve greater attention as aquatic plants are a potential point of transfer of pharmaceuticals from aquatic ecosystems to terrestrial food webs.

Adverse effects of the 5-alpha-reductase inhibitor finasteride on Daphnia magna: Endocrine system and lipid metabolism disruption

Finasteride, a steroid 5-alpha reductase inhibitor, is commonly used for the treatment of benign prostatic hyperplasia and hair loss. However, despite continued use, its environmental implications have not been thoroughly investigated. Thus, we investigated the acute and chronic adverse impacts of finasteride on Daphnia magna, a crucial planktonic crustacean in freshwater ecosystems selected as bioindicator organism for understanding the ecotoxicological effects. Chronic exposure (for 23 days) to finasteride negatively affected development and reproduction, leading to reduced fecundity, delayed first brood, reduced growth, and reduced neonate size. Additionally, acute exposure (< 24 h) caused decreased expression levels of genes crucial for reproduction and development, especially EcR-A/B (ecdysone receptors), Jhe (juvenile hormone esterase), and Vtg2 (vitellogenin), with oxidative stress-related genes. Untargeted lipidomics/metabolomic analyses revealed lipidomic alteration, including 19 upregulated and 4 downregulated enriched lipid ontology categories, and confirmed downregulation of metabolites. Pathway analysis implicated significant effects on metabolic pathways, including the pentose phosphate pathway, histidine metabolism, beta-alanine metabolism, as well as alanine, aspartate, and glutamate metabolism. This comprehensive study unravels the intricate molecular and metabolic responses of D. magna to finasteride exposure, underscoring the multifaceted impacts of this anti-androgenic compound on a keystone species of freshwater ecosystems. The findings emphasize the importance of understanding the environmental repercussions of widely used pharmaceuticals to protect biodiversity in aquatic ecosystems.

Cross-Species Extrapolation of Biological Data to Guide the Environmental Safety Assessment of Pharmaceuticals-The State of the Art and Future Priorities

The extrapolation of biological data across species is a key aspect of biomedical research and drug development. In this context, comparative biology considerations are applied with the goal of understanding human disease and guiding the development of effective and safe medicines. However, the widespread occurrence of pharmaceuticals in the environment and the need to assess the risk posed to wildlife have prompted a renewed interest in the extrapolation of pharmacological and toxicological data across the entire tree of life. To address this challenge, a biological "read-across" approach, based on the use of mammalian data to inform toxicity predictions in wildlife species, has been proposed as an effective way to streamline the environmental safety assessment of pharmaceuticals. Yet, how effective has this approach been, and are we any closer to being able to accurately predict environmental risk based on known human risk? We discuss the main theoretical and experimental advancements achieved in the last 10 years of research in this field. We propose that a better understanding of the functional conservation of drug targets across species and of the quantitative relationship between target modulation and adverse effects should be considered as future research priorities. This pharmacodynamic focus should be complemented with the application of higher-throughput experimental and computational approaches to accelerate the prediction of internal exposure dynamics. The translation of comparative (eco)toxicology research into real-world applications, however, relies on the (limited) availability of experts with the skill set needed to navigate the complexity of the problem; hence, we also call for synergistic multistakeholder efforts to support and strengthen comparative toxicology research and education at a global level. Environ Toxicol Chem 2024;43:513-525. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Synthesis and application of clinically approved small-molecule drugs targeting androgen receptor

Androgen receptor (AR) plays a crucial role in various physiological processes. Dysregulation of AR signaling has been implicated in several diseases, such as prostate cancer and androgenetic alopecia. Therefore, the development of drugs that specifically target AR has gained significant attention in the field of drug discovery. This review provides an overview of the synthetic routes of clinically approved small molecule drugs targeting AR and discusses the clinical applications of these drugs in the treatment of AR-related diseases. The review also highlights the challenges and future perspectives in this field, including the need for improved drug design and the exploration of novel therapeutic targets. Through an integrated analysis of the therapeutic applications, synthetic methodologies, and mechanisms of action associated with these approved drugs, this review facilitates a holistic understanding of the versatile roles and therapeutic potential of AR-targeted interventions. Overall, this comprehensive review serves as a valuable resource for medicinal chemists interested in the development of small-molecule drugs targeting AR.

Cloning, computational analysis and expression profiling of steroid 5 alpha-reductase 1 (SRD5A1) gene during reproductive phases and ovatide stimulation in endangered catfish, Clarias magur

The cloning and characterization of the complete coding sequence of the Clarias magur SRD5A1 (CmSRD5A1) gene, which encodes an enzyme responsible for regulating steroid levels by converting testosterone into 5α-dihydrotestosterone (DHT), have been successfully achieved. DHT plays a vital role in enabling the complete expression of testosterone's actions in neuroendocrine tissues. The ORF of the full-length cDNA sequence of SRD5A1 was 795 bp, translating into 265 amino acids, with a total length of 836 bp including UTRs. Like other vertebrates, the signal peptide analysis revealed that SRD5A1 is a non-secretory protein, and hydropathy profiles indicated that it is hydrophobic in nature. The 3D structure of CmSRD5A1 sequence generated above was predicted using highly accurate AlphaFold 2 in Google Colab online platform. CmSRD5A1 contains seven transmembrane helices connected by six loops, with the N-termini located on the periplasmic side and C-termini on the cytosolic side. Structural superimposition with known bacterial and human SRD5As showed very high structural similarity. The electrostatic potential calculation and surface analysis of CmSRD5A1 revealed the presence of a large cavity with two openings one highly electropositive towards the cytosolic side and another relatively neutral towards the transmembrane region. The structural comparison revealed that the electropositive side of the cavity should bind to NADPH and the steroid hormone in the hydrophobic environment. Polar residues binding to NADPH are highly conserved and the same as known strictures. The conserved residues involved in hydrogen bonding with the ketone group at C-3 in the steroids hence fevering Δ4 double-bond reduction are identified as E66 and Y101. Our findings showed that SRD5A1 expression was lower during the spawning phase than the preparatory phase in female fish, while the administration of Ovatide (a GnRH analogue) resulted in up-regulation of expression after 6 h of injection in the ovary. In males, the lowest expression was observed during the preparatory phase and peaked at 16 h post- Ovatide injection in the testis. The expression of SRD5A1 in the brain of female fish was slightly higher during the Ovatide stimulation phase than the spawning phase. This study represents the first report on the cloning and characterization of the full-length cDNA of SRD5A1 in Indian catfish.

Effects of carbamazepine on the central nervous system of zebrafish at human therapeutic plasma levels

The fish plasma model (FPM) facilitated the environmental risk assessment of human drugs by using existing data on human therapeutic plasma concentrations (HTPCs) and predicted fish plasma concentrations (FPCs). However, studies on carbamazepine (CMZ) with both the mode of action (MOA) based biological effects at molecular level (such as neurotransmitter and gene level) and measured FPCs are lacking. Bioconcentration of CMZ in adult zebrafish demonstrated that the FPM underestimated the bioconcentration factors (BCFs) in plasma at environmental CMZ exposure concentrations (1-100 μg/L). CMZ significantly increased Glu and GABA, decreased ACh and AChE as well as inhibited the transcription levels of gabra1, grin1b, grin2b, gad1b, and abat when the actual FPCs were in the ranges of 1/1000 HTPC to HTPC. It is the first read-across study of CMZ integrating MOA-based biological effects at molecular level and FPCs. This study facilitates model performance against a range of different drug classes.

Consequences of steroid-5α-reductase deficiency and inhibition in vertebrates

In 1974, a lack of 5α-dihydrotestosterone (5α-DHT), the most potent androgen across species except for fish, was shown to be the origin of a type of pseudohermaphrodism in which boys have female-like external genitalia. This human intersex condition is linked to a mutation in the steroid-5α-reductase type 2 (SRD5α2) gene, which usually produces an important enzyme capable of reducing the Δ⁴-ene of steroid C-19 and C-21 into a 5α-stereoisomer. Seeing the potential of SRD5α2 as a target for androgen synthesis, pharmaceutical companies developed 5α-reductase inhibitors (5ARIs), such as finasteride (FIN) and dutasteride (DUT) to target SRD5α2 in benign prostatic hyperplasia and androgenic alopecia. In addition to human treatment, the development of 5ARIs also enabled further research of SRD5α functions. Therefore, this review details the morphological, physiological, and molecular effects of the lack of SRD5α activity induced by both SRD5α mutations and inhibitor exposures across species. More specifically, data highlights 1) the role of 5α-DHT in the development of male secondary sexual organs in vertebrates and sex determination in non-mammalian vertebrates, 2) the role of SRD5α1 in the synthesis of the neurosteroid allopregnanolone (ALLO) and 5α-androstane-3α,17β-diol (3α-diol), which are involved in anxiety and sexual behavior, respectively, and 3) the role of SRD5α3 in N-glycosylation. This review also features the lesser known functions of SRD5αs in steroid degradation in the uterus during pregnancy and glucocorticoid clearance in the liver. Additionally, the review describes the regulation of SRD5αs by the receptors of androgens, progesterone, estrogen, and thyroid hormones, as well as their differential DNA methylation. Factors known to be involved in their differential methylation are age, inflammation, and mental stimulation. Overall, this review helps shed light on the various essential functions of SRD5αs across species.

Early embryonic exposure of freshwater gastropods to pharmaceutical 5-alpha-reductase inhibitors results in a surprising open-coiled "banana-shaped" shell

In vertebrates, the steroidogenesis enzyme 5α-reductase converts testosterone to the more potent androgen 5α-dihydrotestosterone. Homologues of 5α-reductase genes have been identified in molluscs. However, recent findings suggest that vertebrate-type steroid androgens are not utilised in molluscan reproductive development. Genomic searches have revealed that molluscs do not possess many of the steroidogenic enzymes required to make testosterone, nor a nuclear androgen receptor. Consequently, the role of 5α-reductase in molluscs presents a mystery. Here, developmental exposures of Biomphalaria glabrata to selective pharmaceutical 5α-reductase inhibitors elicited a strong, highly reproducible phenotypic response characterised by the development of elongated "banana-shaped" shell morphology. In comparison to untreated snails, the shells are open-coiled and the whorls are unattached. Dutasteride (5α-reductase inhibitor) is approximately 10-times more potent at provoking the banana-shaped shell phenotype than finasteride, paralleling the pharmaceuticals' efficacy in humans. Other enzyme inhibitors with different modes of action were tested to investigate the specificity of the phenotype. However, only the pharmaceutical 5α-reductase inhibitors provoked the response. Dutasteride elicited the same phenotype in a second gastropod, Physella acuta. In the absence of evidence for de novo androgen steroidogenesis in molluscs, these findings suggest that novel substrates for 5α-reductase exist in gastropods, lending support to the contention that molluscan endocrinology differs from the well-characterised vertebrate endocrine system.

A Review on Biological Processes for Pharmaceuticals Wastes Abatement-A Growing Threat to Modern Society

Over the last decades, the production and consumption of pharmaceuticals and health care products grew manifold, allowing an increase in life expectancy and a better life quality for humans and animals, in general. However, the growth in pharmaceuticals production and consumption comes with an increase in waste production, which creates a number of challenges as well as opportunities for the waste management industries. The conventional current technologies used to treat effluents have shown to be inefficient to remove or just to reduce the concentrations of these types of pollutants to the legal limits. The present review provides a thorough state-of-the-art overview on the use of biological processes in the rehabilitation of ecosystems contaminated with the pharmaceutical compounds most commonly detected in the environment and eventually more studied by the scientific community. Among the different biological processes, special attention is given to biosorption and biodegradation.

Overview of Monitoring Techniques for Evaluating Water Quality at Potable Reuse Treatment Facilities

Needless to say, the safety of treated water for potable reuse must be definitively ensured. Numerous methods are available for assessing water quality; it's important to understand their challenges and limitations.

Endocrine-disrupting chemicals in aquatic environment: what are the risks for fish gametes?

Over the past 25 years, extensive research in vertebrate species has identified several genomic pathways altered by exposures to anthropogenic chemicals with hormone-like activity mediated by their interaction with nuclear receptors. In addition, many pollutants have been shown to interfere with non-genomic (non-classical) pathways, but this mechanism of endocrine disruption is still poorly understood. Recently, the number of publications describing the effects of Endocrine disrupting chemicals (EDCs) on fish reproduction, focusing on the deregulation of the hypothalamus-pituitary-gonadal axis as well as on gamete quality, significantly increased. Depending on their ability to mimic endogenous hormones, the may differently affect male or female reproductive physiology. Inhibition of gametogenesis, development of intersex gonads, alteration of the gonadosomatic index, and decreased fertility rate have been largely documented. In males, alterations of sperm density, motility, and fertility have been observed in several wild species. Similar detrimental effects were described in females, including negative outcomes on oocyte growth and maturation plus the occurrence of apoptotic/autophagic processes. These pathways may affect gamete viability considered as one of the major indicators of reproductive endocrine disruption. Pollutants act also at DNA level producing DNA mutations and changes in epigenetic pathways inducing specific mechanisms of toxicity and/or aberrant cellular responses that may affect subsequent generation(s) through the germline. In conclusion, this review summarizes the effects caused by EDC exposure on fish reproduction, focusing on gametogenesis, giving a general overview of the different aspects dealing with this issue, from morphological alteration, deregulation of steroidogenesis, hormonal synthesis, and occurrence of epigenetic process.

Role of 5α-dihydrotestosterone in testicular development of gilthead seabream following finasteride administration

In teleosts, spermatogenesis is regulated by pituitary gonadotropins and sex steroids. 5α-dihydrotestosterone (DHT), derived from testosterone (T) through the action of 5α-reductase, has recently been suggested to play a physiologically important role in some fish species. In this study, gilthead seabream, Sparus aurata L., males received an implant of 1μgT/g body mass (bm) or vehicle alone and, 7days later, 1mg finasteride (FIN, an inhibitor of 5α-reductase)/kg bm or vehicle. Serum levels of T, 11-ketotestosterone (11KT), DHT and 17β-estradiol (E₂), and the mRNA levels of the main enzymes involved in their synthesis, were analysed. T promoted a transient increase in the serum levels of T, 11KT and E₂ but a decrease in those of DHT at day 15 following T injection, in accordance with the up-regulation of mRNA levels of the enzymes involved in T transformation to 11KT (coding genes: cyp11b1 and hsd11b) and the down-regulation of mRNA levels of the enzyme responsible for T transformation to DHT (coding gene: srd5a). Interestingly, a similar effect was observed when FIN was injected. However, when fish were injected with T and FIN successively (T+FIN), control levels were not recovered at the end of the experimental period (28days). DHT seems to regulate E₂ serum levels via the down-regulation of mRNA levels of aromatase (coding gene: cyp19a1a), which is needed for the transformation of T into E₂. The testis histology, together with the proliferative rates recorded upon T, FIN or T+FIN treatment, suggests that DHT is involved in the onset of the meiotic phase of spermatogenesis.

Review on fate and mechanism of removal of pharmaceutical pollutants from wastewater using biological approach

Due to research advancement and discoveries in the field of medical science, maintains and provides better human health and safer life, which lead to high demand for production of pharmaceutical compounds with a concomitant increase in population. These pharmaceutical (biologically active) compounds were not fully metabolized by the body and excreted out in wastewater. This micro-pollutant remains unchanged during wastewater treatment plant operation and enters into the receiving environment via the discharge of treated water. Persistence of pharmaceutical compounds in both surface and ground waters becomes a major concern due to their potential eco-toxicity. Pharmaceuticals (emerging micro-pollutants) deteriorate the water quality and impart a toxic effect on living organisms. Therefore, from last two decades, plenty of studies were conducted on the occurrence, impact, and removal of pharmaceutical residues from the environment. This review provides an overview on the fate and removal of pharmaceutical compounds via biological treatment process.

Prioritization of pharmaceuticals for potential environmental hazard through leveraging a large-scale mammalian pharmacological dataset

The potential for pharmaceuticals in the environment to cause adverse ecological effects is of increasing concern. Given the thousands of active pharmaceutical ingredients (APIs) that can enter the aquatic environment through human and/or animal (e.g., livestock) waste, a current challenge in aquatic toxicology is identifying those that pose the greatest risk. Because empirical toxicity information for aquatic species is generally lacking for pharmaceuticals, an important data source for prioritization is that generated during the mammalian drug development process. Applying concepts of species read-across, mammalian pharmacokinetic data were used to systematically prioritize APIs by estimating their potential to cause adverse biological consequences to aquatic organisms, using fish as an example. Mammalian absorption, distribution, metabolism, and excretion (ADME) data (e.g., peak plasma concentration, apparent volume of distribution, clearance rate, and half-life) were collected and curated, creating the Mammalian Pharmacokinetic Prioritization For Aquatic Species Targeting (MaPPFAST) database representing 1070 APIs. From these data, a probabilistic model and scoring system were developed and evaluated. Individual APIs and therapeutic classes were ranked based on clearly defined read-across assumptions for translating mammalian-derived ADME parameters to estimate potential hazard in fish (i.e., greatest predicted hazard associated with lowest mammalian peak plasma concentrations, total clearance and highest volume of distribution, half-life). It is anticipated that the MaPPFAST database and the associated API prioritization approach will help guide research and/or inform ecological risk assessment.

Internal exposure dynamics drive the Adverse Outcome Pathways of synthetic glucocorticoids in fish

The Adverse Outcome Pathway (AOP) framework represents a valuable conceptual tool to systematically integrate existing toxicological knowledge from a mechanistic perspective to facilitate predictions of chemical-induced effects across species. However, its application for decision-making requires the transition from qualitative to quantitative AOP (qAOP). Here we used a fish model and the synthetic glucocorticoid beclomethasone dipropionate (BDP) to investigate the role of chemical-specific properties, pharmacokinetics, and internal exposure dynamics in the development of qAOPs. We generated a qAOP network based on drug plasma concentrations and focused on immunodepression, skin androgenisation, disruption of gluconeogenesis and reproductive performance. We showed that internal exposure dynamics and chemical-specific properties influence the development of qAOPs and their predictive power. Comparing the effects of two different glucocorticoids, we highlight how relatively similar in vitro hazard-based indicators can lead to different in vivo risk. This discrepancy can be predicted by their different uptake potential, pharmacokinetic (PK) and pharmacodynamic (PD) profiles. We recommend that the development phase of qAOPs should include the application of species-specific uptake and physiologically-based PK/PD models. This integration will significantly enhance the predictive power, enabling a more accurate assessment of the risk and the reliable transferability of qAOPs across chemicals.

Environmental chemicals active as human antiandrogens do not activate a stickleback androgen receptor but enhance a feminising effect of oestrogen in roach

Sexual disruption is reported in wild fish populations living in freshwaters receiving discharges of wastewater treatment works (WwTW) effluents and is associated primarily with the feminisation of males by exposure to oestrogenic chemicals. Antiandrogens could also contribute to the feminisation of male fish, but there are far less data supporting this hypothesis and almost nothing is known for the effects of oestrogens in combination with antiandrogens in fish. We conducted a series of in vivo exposures in two fish species to investigate the potency on reproductive-relevant endpoints of the antiandrogenic antimicrobials triclosan (TCS), chlorophene (CP) and dichlorophene (DCP) and the resin, abietic acid (AbA), all found widely in WwTW effluents. We also undertook exposures with a mixture of antiandrogens and a mixture of antiandrogens in combination with the oestrogen 17α-ethinyloestradiol (EE2). In stickleback (Gasterosteus aculeatus), DCP showed a tendency to reduce spiggin induction in females androgenised by dihydrotestosterone (DHT), but these findings were not conclusive. In roach (Rutilus rutilus), exposures to DCP (178 days), or a mixture of TCS, CP and AbA (185 days), or to the model antiandrogen flutamide (FL, 178 days) had no effect on gonadal sex ratio or on the development of the reproductive ducts. Exposure to EE2 (1.5ng/L, 185 days) induced feminisation of the ducts in 17% of the males and in the mixture of antiandrogens (TCS, CP, AbA) in combination with EE2, almost all (96%) of the males had a feminised reproductive ducts. In stickleback androgen receptor (ARα and ARβ) transactivation assays, the model antiandrogens, FL and procymidone inhibited 11-ketotestosterone (11-KT) induced receptor activation, but none of the human antiandrogens, TCS, CP, DCP and AbA had an effect. These data indicate that antimicrobial antiandrogens in combination can contribute to the feminisation process in exposed males, but they do not appear to act through the androgen receptor in fish.

Progesterone is actively metabolized to 5α-pregnane-3,20-dione and 3β-hydroxy-5α-pregnan-20-one by the marine mussel Mytilus galloprovincialis

Progesterone (P4) and synthetic progestins enter the aquatic environment through wastewater treatment plant effluents and agricultural run-off, posing potential risks to aquatic organisms due to their biological activity. P4 is a precursor of a number of steroids in vertebrates, including estrogens and androgens. Mussels Mytilus galloprovincialis were exposed to P4 at the ng to low μg/L range (0.02-10μg/L) for 7 days with the aim of (a) assessing potential alterations on endogenous steroids as a consequence of exposure, and (b) describing the enzymatic pathways involved in P4 metabolism in mussels. No significant alteration of the levels of testosterone (T) and estradiol (E2) was observed in mantle/gonad tissue of exposed mussels, in spite of a 5.6-fold increase in immunoreactive T in those exposed to 10μg P4/L, which was attributed to cross-reactivity. P4 was actively metabolized to 5α-pregnane-3,20-dione (5α-DHP) and 3β-hydroxy-5α-pregnan-20-one (3β,20-one) in digestive gland, with no evidence for the synthesis of 17α-hydroxyprogesterone or androstenedione. The metabolism of P4 to 5α-DHP was not altered by exposure. Histological examination of the gonads suggested that exposure to 10μg/L P4 induced gamete maturation and release in mussels. Nonetheless, environmental concentrations of P4 are unlikely to have an endocrine action in mussels.

Evaluation of the 5α-reductase inhibitor finasteride on reproduction and gonadal development in medaka, Oryzias latipes

5-α reductase (5αR) inhibitors have an anti-androgenic effect in mammals because they inhibit the conversion of testosterone to the potent androgen, dihydrotestosterone. Finasteride is a type-2 5αR inhibitor that is used as a human pharmaceutical for the treatment of prostate cancer, benign prostate hyperplasia and male pattern baldness. This study evaluated the impacts of finasteride (50, 500 and 5000μg/L) on the development and reproduction of medaka (Oryzias latipes) exposed continuously over multiple generations (F0, F1 and F2). The exposure was initiated with reproductively mature fish (F0 generation) and continued until the hatching of the F2 generation. There were no significant effects on survival, fecundity or fertility in the F0 (50, 500, 5000μg/L) and F1 (50, 500μg/L) generations. The F1 generation exposed to 5000μg/L exhibited significant mortality. Histopathology of the gonads demonstrated that medaka and pre-clinical species respond similarly to finasteride exposure. Intersex condition and maldeveloped gonads were observed in F0 generation males exposed to 5000μg/L and F1 generation males exposed to 500μg/L. F1 generation males exposed to 500μg/L displayed reduced gonadosomatic index with an increased incidence of testicular degeneration. Males in both generations exhibited an increased incidence of Leydig cell hyperplasia at concentrations ⩾500μg/L. F0 generation females exposed to 5000μg/L exhibited increased gonadosomatic index. An increased prevalence of accelerated post-ovulatory follicle involution was observed in females at concentrations ⩾500μg/L in both generations. The gonadal changes induced by finasteride support the idea that 5-α reductase inhibition impacts androgen signaling in fish. Results from this study are discussed in the context of differential expression of the androgen receptor between species of fish.

Pharmaceuticals and personal care products: A critical review of the impacts on fish reproduction

Research in environmental toxicology involving pharmaceuticals and personal care products (PPCPs) has increased greatly over the last 10-15 years. Much research has been focused on the endocrine-disrupting potential of PPCPs, as they relate to negative population impacts of aquatic organisms. This review assesses the current data on the reported effects of PPCPs on fish reproduction with an emphasis on fecundity, a predictor of population effects. Studies of both individual PPCPs and PPCP mixtures are presented. As the majority of individual PPCP studies reviewed demonstrate negative effects on fish fecundity, we relate these findings to detected surface water concentrations of these compounds. Very few studies involving PPCP mixtures have been conducted; however, the need for these types of studies is warranted as fish are most likely exposed to mixtures of PPCPs in the wild. In addition, laboratory and field assessments of wastewater treatment plant (WWTP) effluents, a major source of PPCPs, are reviewed. Much of the data provided from these assessments are variable and do not generally demonstrate negative impacts on reproduction, or the studies are unable to directly associate observed effects with WWTP effluents. Finally, future research considerations are outlined to provide an avenue into understanding how wild populations of fish are affected by PPCPs. These considerations are aimed at determining the adaptation potential of fish exposed to mixtures of PPCPs over multiple generations. As global use of PPCPs continually rises, the need to discern the effects of chronic exposure to PPCPs is greatly increased.

Improving environmental risk assessment of human pharmaceuticals

This paper presents 10 recommendations for improving the European Medicines Agency's guidance for environmental risk assessment of human pharmaceutical products. The recommendations are based on up-to-date, available science in combination with experiences from other chemical frameworks such as the REACH-legislation for industrial chemicals. The recommendations concern: expanding the scope of the current guideline; requirements to assess the risk for development of antibiotic resistance; jointly performed assessments; refinement of the test proposal; mixture toxicity assessments on active pharmaceutical ingredients with similar modes of action; use of all available ecotoxicity studies; mandatory reviews; increased transparency; inclusion of emission data from production; and a risk management option. We believe that implementation of our recommendations would strengthen the protection of the environment and be beneficial to society. Legislation and guidance documents need to be updated at regular intervals in order to incorporate new knowledge from the scientific community. This is particularly important for regulatory documents concerning pharmaceuticals in the environment since this is a research field that has been growing substantially in the last decades.

Waterborne beclomethasone dipropionate affects the physiology of fish while its metabolite beclomethasone is not taken up

Asthma is commonly treated with inhalable glucocorticosteroids, including beclomethasone dipropionate (BDP). This is a synthetic prodrug which is metabolized to the more active monopropionate (BMP) and free beclomethasone in humans. To evaluate potential effects of residual drugs on fish, we conducted a 14 day flow-through exposure experiment with BDP and beclomethasone using rainbow trout, and analyzed effects on plasma glucose, hepatic glutathione and catalase activity together with water and body concentrations of the BDP, BMP and beclomethasone. We also analyzed hepatic gene expression in BDP-exposed fish by microarray and quantitative PCR. Beclomethasone (up to 0.65 μg/L) was not taken up in the fish while BDP (0.65 and 0.07 μg/L) resulted in accumulation of both beclomethasone, BMP and BDP in plasma, reaching levels up to those found in humans during therapy. Accordingly, exposure to 0.65 μg/L of BDP significantly increased blood glucose as well as oxidized glutathione levels and catalase activity in the liver. Exposure to beclomethasone or the low concentration of BDP had no effect on these endpoints. Both exposure concentrations of BDP resulted in significantly higher transcript abundance of phosphoenolpyruvate carboxykinase involved in gluconeogenesis, and of genes involved in immune responses. As only the rapidly metabolized prodrug was potent in fish, the environmental risks associated with the use of BDP are probably small. However, the observed physiological effects in fish of BDP at plasma concentrations known to affect human physiology provides valuable input to the development of read-across approaches in the identification of pharmaceuticals of environmental concern.

Effects of 5α-dihydrotestosterone on expression of genes related to steroidogenesis and spermatogenesis during the sex determination and differentiation periods of the pejerrey, Odontesthes bonariensis

Sex steroid hormones are important players in the control of sex differentiation by regulating gonadal development in teleosts. Although estrogens are clearly associated with the ovarian differentiation in teleosts, the effects of androgens on early gonadal development are still a matter of debate. Traditionally, 11-ketotestosterone (11-KT) is considered the major androgen in fish; however, 5α-dihydrotestosterone (5α-DHT), the most potent androgen in tetrapods, was recently found in fish testis and plasma, but its physiological role is still unknown. In this context, the expression of genes associated with steroidogenesis and spermatogenesis, body growth and sex differentiation were assessed in Odontesthes bonariensis larvae fed with food supplemented with two doses of 5α-DHT (0.1 and 10μg/g of food) from hatching to 6weeks of age. At the lowest dose, 5α-DHT treated larvae showed an estrogenic gene expression pattern, with low hsd11b2 and high cyp19a1a and er2 expression levels with no differences in sex ratio. At the highest dose, 5α-DHT produced a male-shifted sex ratio and the larvae exhibited a gene expression profile characteristic of an advancement of spermatogenesis, with inhibition of amh and stimulation of ndrg3. No differences were observed in somatic growth. These results suggest that in this species, 5α-DHT could have a role on sex differentiation and its effects can differ according to the dose.

An integrated approach for prioritizing pharmaceuticals found in the environment for risk assessment, monitoring and advanced research

Numerous active pharmaceutical ingredients (APIs), approved prior to enactment of detailed environmental risk assessment (ERA) guidance in the EU in 2006, have been detected in surface waters as a result of advancements in analytical technologies. Without adequate knowledge of the potential hazards these APIs may pose, assessing their environmental risk is challenging. As it would be impractical to commence hazard characterization and ERA en masse, several approaches to prioritizing substances for further attention have been published. Here, through the combination of three presentations given at a recent conference, "Pharmaceuticals in the Environment, Is there a problem?" (Nîmes, France, June 2013) we review several of these approaches, identify salient components, and present available techniques and tools that could facilitate a pragmatic, scientifically sound approach to prioritizing APIs for advanced study or ERA and, where warranted, fill critical data gaps through targeted, intelligent testing. We further present a modest proposal to facilitate future prioritization efforts and advanced research studies that incorporates mammalian pharmacology data (e.g., adverse outcomes pathways and the fish plasma model) and modeled exposure data based on pharmaceutical use.

Consumption-based approach for predicting environmental risk in Greece due to the presence of antimicrobials in domestic wastewater

The main objective of the current study was to estimate the potential environmental risks associated with human consumption of antimicrobials in Greece. Consumption data was collected for the 24 most often used antimicrobials for the years 2008-2010, and their predicted environmental concentrations (PECs) in raw and treated wastewater were calculated using mass balances and literature data on human excretion and elimination efficiency during wastewater treatment. The ecotoxicological risk was estimated by calculating the ratio of PEC to predicted no-effect concentration (PNEC) for three categories of aquatic organisms (algae, daphnids, and fish). PNEC values were calculated based on experimental ecotoxicity data and data originated from the Ecological Structure Activity Relationship (ECOSAR). PEC values in raw sewage ranged between 0.02 μg L(-1) (erythromycin) and 27 μg L(-1) (amoxicillin), while in treated wastewater, the highest concentration was predicted for cefuroxime axetil (6.6 μg L(-1)). Based on acute toxicity data for algae, risk quotient (RQ) values higher than 1 were obtained for 7 out of the 24 target antimicrobials in raw and treated wastewater, while no significant risk was estimated for daphnids and fish. Regarding the possible risk due to the chronic toxicity of antimicrobials, RQ values higher than 80 were obtained for amoxicillin and clarithromycin in algae. The use of baseline toxicity data from ECOSAR showed that the environmental risk from exposure to mixtures of antimicrobials was low for all three aquatic species. However, further studies on toxicity of mixtures should be performed as calculation of toxicity ratio (TR) values showed that 90 % of the target antimicrobials seem to exhibit a specific mode of toxic action when present in mixtures rather than baseline toxicity. As a result, an underestimation of toxicity based on the ECOSAR model is possible for the mixture of target antimicrobials. For Greek rivers where low (dilution factor, D<10) and medium (D=10-100) dilution of wastewater occurs, moderate to high risk is expected due to the existence of individual antimicrobials such as amoxicillin, clarithromycin, ciprofloxacin, azithromycin, erythromycin, and levofloxacin in discharged treated wastewater.

A novel framework for interpretation of data from the fish short-term reproduction assay (FSTRA) for the detection of endocrine-disrupting chemicals

The fish short-term reproduction assay (FSTRA) is a key component of the US Environmental Protection Agency's Endocrine Disruptor Screening Program (EDSP), which uses a weight-of-evidence analysis based on data from several assays to identify the potential for chemicals to act as agonists or antagonists of the estrogen or androgen receptors (ER and AR), or inhibitors of steroidogenic enzymes. The FSTRA considers a variety of mechanistic and apical responses in 21-d exposures with the fathead minnow (Pimephales promelas), including plasma steroid and vitellogenin (VTG; egg yolk protein) concentrations, secondary sex characteristics, gonad size and histopathology, and egg production. Although the FSTRA initially was described several years ago, recent data generation associated with implementation of the EDSP highlighted the need for more formal guidance regarding evaluation of information from the assay. The authors describe a framework for interpretation of FSTRA data relative to perturbation of endocrine pathways of concern to the EDSP. The framework considers end points individually and as suites of physiologically related responses relative to pathway identification. Sometimes changes in single end points can be highly diagnostic (e.g., induction of VTG in males by ER agonists, production of male secondary sex characteristics in females by AR agonists); in other instances, however, multiple, related end points are needed to reliably assess pathway perturbation (e.g., AR antagonism, steroid synthesis inhibition). In addition to describing an interpretive framework, the authors demonstrate its practical utility using publicly available FSTRA data for a wide range of known and hypothesized endocrine-disrupting chemicals. Environ Toxicol Chem 2014;33:2529-2540. Published 2014 Wiley Periodicals Inc., on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Quantitative cross-species extrapolation between humans and fish: the case of the anti-depressant fluoxetine

Fish are an important model for the pharmacological and toxicological characterization of human pharmaceuticals in drug discovery, drug safety assessment and environmental toxicology. However, do fish respond to pharmaceuticals as humans do? To address this question, we provide a novel quantitative cross-species extrapolation approach (qCSE) based on the hypothesis that similar plasma concentrations of pharmaceuticals cause comparable target-mediated effects in both humans and fish at similar level of biological organization (Read-Across Hypothesis). To validate this hypothesis, the behavioural effects of the anti-depressant drug fluoxetine on the fish model fathead minnow (Pimephales promelas) were used as test case. Fish were exposed for 28 days to a range of measured water concentrations of fluoxetine (0.1, 1.0, 8.0, 16, 32, 64 µg/L) to produce plasma concentrations below, equal and above the range of Human Therapeutic Plasma Concentrations (H_TPCs). Fluoxetine and its metabolite, norfluoxetine, were quantified in the plasma of individual fish and linked to behavioural anxiety-related endpoints. The minimum drug plasma concentrations that elicited anxiolytic responses in fish were above the upper value of the H_TPC range, whereas no effects were observed at plasma concentrations below the H_TPCs. In vivo metabolism of fluoxetine in humans and fish was similar, and displayed bi-phasic concentration-dependent kinetics driven by the auto-inhibitory dynamics and saturation of the enzymes that convert fluoxetine into norfluoxetine. The sensitivity of fish to fluoxetine was not so dissimilar from that of patients affected by general anxiety disorders. These results represent the first direct evidence of measured internal dose response effect of a pharmaceutical in fish, hence validating the Read-Across hypothesis applied to fluoxetine. Overall, this study demonstrates that the qCSE approach, anchored to internal drug concentrations, is a powerful tool to guide the assessment of the sensitivity of fish to pharmaceuticals, and strengthens the translational power of the cross-species extrapolation.

Estrogenic activity and cytotoxicity of six anticancer drugs detected in water systems

The aim of the present study was to investigate the in vitro estrogenic and the cytotoxic activity of six cytostatics (5-fluorouracil, capecitabine, cisplatin, doxorubicin, etoposide, and imatinib) belonging to the five classes of Anatomical Therapeutic Classification (ATC) detected in wastewater systems. The estrogenic activity was assessed by YES-assay on Saccharomyces cerevisiae-RMY326 and E-screen on MCF-7 cells. The cytotoxic activity was assessed by MTT Cell Proliferation Assay on the MCF-7 and the MDA-MB-231 cells. The results of estrogenic activity, detected by E-screen and expressed as EC50, showed a high potential of imatinib (10(-7) μM) followed by cisplatin and 5-fluorouracil. Capecitabine was poorly estrogenic while etoposide and doxorubicin EC50 values were not possible to determine. Cytotoxicity was found at concentrations far from those detected in effluents. The potential endocrine activity of the most active drugs could be associated with human and wildlife risk when considering their occurrence in the environment.

Fish on Prozac (and Zoloft): ten years later

A decade has now passed since our research group initially reported several adverse effects of fluoxetine to aquatic organisms commonly employed for developing environmental quality criteria, evaluating whole effluent toxicity, and monitoring ambient toxicity of surface waters and sediments. Our subsequent observation of fluoxetine, sertraline and their active metabolites (norfluoxetine and desmethylsertraline, respectively) accumulating in muscle, liver and brain tissues of three different fish species from an effluent-dominated stream was termed "Fish on Prozac." Here I briefly review some scientific lessons learned from our study of antidepressants and the environment, including opportunities for research, management, environmental education and public outreach. Intrinsic chemical properties of antidepressants and other pharmaceuticals have afforded research in areas ranging from analytical chemistry and comparative pharmacology, to influences of ionization, chirality and adverse outcome pathways on hazard and risk assessment, and further promises to support sustainable molecular design of less hazardous chemicals. Using probabilistic hazard assessment and fish plasma modeling approaches, selective serotonin reuptake inhibitors and tricyclic antidepressants are predicted to result in therapeutic hazard to fish (internal fish plasma level equaling mammalian therapeutic dose) when exposed to water (inhalational) at or below 1μg/L, a common trigger value for environmental assessments. Though many questions remain unanswered, studies of antidepressants in urbanizing aquatic systems have provided, and will continue to develop, an advanced understanding of environmental hazards and risks from pharmaceuticals and other contaminants.

Effects of low concentrations of the antiprogestin mifepristone (RU486) in adults and embryos of zebrafish (Danio rerio): 1. Reproductive and early developmental effects

Effects of synthetic progestins have recently been reported in fish, but potential effects of the synthetic antiprogestin mifepristone (MIF), also called RU486, have not been studied. The present study provides first insights into reproductive effects of MIF in zebrafish in comparison to the progesterone receptor agonist, progesterone (P4). We carried out a reproductive study using breeding groups of adult zebrafish. After a 14 day pre-exposure, zebrafish were exposed for 21 days to 5, 39, 77 ng/L MIF, 25 ng/L P4 and water and solvent controls. In addition, embryos originating from exposed adult fish were continuously exposed to 3, 15, 26 ng/L MIF, and 254 ng/L P4, respectively, for 96 h post fertilization. We found a significant U-shaped increase in egg production after exposure to 5 and 77 ng/L MIF, but no effects at 25 ng/L P4. Levels of sex steroid hormones in blood plasma of adult males (11-ketotestosterone) and females (17 β-estradiol) were not altered. In addition to an increase of mature vitellogenic oocytes in ovaries of females exposed to MIF and P4, we observed several histopathological changes in ovaries, including post-ovulatory follicles, atretic follicles and proteinaceous fluid. Male gonads showed no or less alterations and no histopathological effects. Fertility of eggs and hatching success of embryos (F1 generation) was not affected at 3-26 ng/L MIF and 254 ng/L P4, respectively. The data lead to the conclusion that trace quantities of MIF affect reproduction of zebrafish and ovaries of female zebrafish. Effects on transcriptional changes in adult and embryonic zebrafish of this study in comparison to in vitro effects are reported in the associated report (Blüthgen et al., 2013a).

The read-across hypothesis and environmental risk assessment of pharmaceuticals

Pharmaceuticals in the environment have received increased attention over the past decade, as they are ubiquitous in rivers and waterways. Concentrations are in sub-ng to low μg/L, well below acute toxic levels, but there are uncertainties regarding the effects of chronic exposures and there is a need to prioritise which pharmaceuticals may be of concern. The read-across hypothesis stipulates that a drug will have an effect in non-target organisms only if the molecular targets such as receptors and enzymes have been conserved, resulting in a (specific) pharmacological effect only if plasma concentrations are similar to human therapeutic concentrations. If this holds true for different classes of pharmaceuticals, it should be possible to predict the potential environmental impact from information obtained during the drug development process. This paper critically reviews the evidence for read-across, and finds that few studies include plasma concentrations and mode of action based effects. Thus, despite a large number of apparently relevant papers and a general acceptance of the hypothesis, there is an absence of documented evidence. There is a need for large-scale studies to generate robust data for testing the read-across hypothesis and developing predictive models, the only feasible approach to protecting the environment.

Identification and quantification of 5α-dihydrotestosterone in the teleost fathead minnow (Pimephales promelas) by gas chromatography-tandem mass spectrometry

The steroid hormone 5α-dihydrotestosterone (DHT) is one of the most physiologically important androgens in male vertebrates, with the exception of teleost fish, in which it is generally assumed that DHT does not play any major physiological role. However, this assumption is challenged by the fact that all the components involved in DHT biosynthesis and action are present and evolutionary conserved in teleost fish. In fact, testosterone (T) is converted into DHT by two isoforms of the enzyme steroid-5-alpha-reductase (5αR), and both 5αRs gene expression and enzymatic activity have been detected in several tissues of different teleost species, which also have an androgen receptor with high binding affinity to DHT. This body of evidence strongly suggest that DHT is synthesised by teleost fish. We investigated this hypothesis using the cyprinid fathead minnow (Pimephales promelas) as the experimental model. The study of the evolutionary and functional conservation of 5αRs in teleost fish was used to support the experimental approach, based on an ultrasensitive gas chromatography-tandem mass spectrometry (GC-MS/MS) method to identify and measure simultaneously T and DHT in fathead minnow biological fluids and tissues. The analyses were performed using plasma samples collected from both male and female adult fish and samples of testicular tissue collected from sexually mature males. Both T and DHT were identified and quantified in all the samples analysed, and in particular, the high concentrations of DHT quantified in the testes suggested that these organs are a likely site of synthesis of DHT in the teleost fathead minnow, as they are in mammals. These results may represent the basis for future studies aimed at elucidating the physiological role, if any, of DHT in teleost fish.

Short and long-term effects of clofibric acid and diclofenac on certain biochemical and ionoregulatory responses in an Indian major carp, Cirrhinus mrigala

Extensive use of pharmaceuticals in human and veterinary medicine and aquaculture practices pose a serious threat to aquatic organisms. In the present investigation, Cirrhinus mrigala an Indian major carp was exposed to different concentrations of clofibric acid (CA) and diclofenac (DCF) and certain biochemical and ionoregulatory responses were assessed under short and long term exposures. During short-term (96h) exposure period, plasma glucose and sodium (Na(+)) levels were increased at all concentrations (1, 10 and 100μgL(-1)) of CA and DCF treated fish. Plasma protein and chloride (Cl(-)) levels were found to be decreased at all concentrations of CA and DCF exposed fish comparatively to control groups. Meanwhile an increase in plasma potassium (K(+)) level was noted in fish exposed to CA treatments alone and in DCF treatments it was decreased. In long-term exposure (35d), plasma Na(+) and Cl(-) levels were found to be significantly increased at all concentration of CA and DCF. However, a biphasic trend was observed in plasma glucose, protein and K(+) levels. In both the treatments, a significant (P<0.01 and P<0.05) changes were observed in all parameters measured in fish exposed to different concentrations of CA and DCF. The results of the present investigation indicate that both the drugs caused significant changes in biochemical and ionoregulatory responses of fish at all concentrations. The alterations of these parameters can be useful in monitoring of pharmaceutical residues present in aquatic environment.