Nest-defense behaviors in fathead minnows after lifecycle exposure to the antidepressant venlafaxine

Zygotic Exposure to Venlafaxine Disrupts the Circadian Locomotor Activity Behaviour in Zebrafish Larvae

The antidepressant venlafaxine, a selective serotonin and norepinephrine reuptake inhibitor, is commonly prescribed to treat major depressive disorder and is found at high concentrations in the aquatic environment. Concerns have been raised related to the health of aquatic organisms in response to this nontargeted pharmaceutical exposure. For instance, we previously demonstrated that exposure to venlafaxine perturbs neurodevelopment, leading to behavioural alterations in zebrafish (Danio rerio). We also observed disruption in serotonin expression in the pineal and raphe, regions critical in regulating circadian rhythms, leading us to hypothesize that zygotic exposure to venlafaxine disrupts the circadian locomotor rhythm in larval zebrafish. To test this, we microinjected zebrafish embryos with venlafaxine (1 or 10 ng) and recorded the locomotor activity in 5-day-old larvae over a 24-h period. Venlafaxine deposition reduced larval locomotor activity during the light phase, but not during the dark phase of the diurnal cycle. The melatonin levels were higher in the dark compared to during the light photoperiod and this was not affected by embryonic venlafaxine deposition. Venlafaxine exposure also did not affect the transcript abundance of clock genes, including clock1a, bmal2, cry1a and per2, which showed a clear day/night rhythmicity. A notable finding was that exposure to luzindole, a melatonin receptor antagonist, decreased the locomotor activity in the control group in light, whereas the activity was higher in larvae raised from the venlafaxine-deposited embryos. Overall, zygotic exposure to venlafaxine disrupts the locomotor activity of larval zebrafish fish during the day, demonstrating the capacity of antidepressants to disrupt the circadian rhythms in behaviour. Our results suggest that disruption in melatonin signalling may be playing a role in the venlafaxine impact on circadian behaviour, but further investigation is required to elucidate the possible mechanisms in larval zebrafish.

Effects of metformin on wild fathead minnows (Pimephales promelas) using in-lake mesocosms in a boreal lake ecosystem

Due to its widespread use for the treatment of Type-2 diabetes, metformin is routinely detected in surface waters globally. Laboratory studies have shown that environmentally relevant concentrations of metformin can adversely affect the health of adult fish, with effects observed more frequently in males. However, the potential risk to wild fish populations has yet to be fully elucidated and remains a topic of debate. To explore whether environmentally relevant metformin exposure poses a risk to wild fish populations, the present study exposed wild fathead minnows (Pimephales promelas) to 5 or 50 μg/L metformin via 2 m diameter in-lake mesocosms deployed in a natural boreal lake in Northern Ontario at the International Institute for Sustainable Development - Experimental Lakes Area (IISD-ELA). Environmental monitoring was performed at regular intervals for 8-weeks, with fish length, weight (body, liver and gonad), condition factor, gonadosomatic index, liver-somatic index, body composition (water and biomolecules) and hematocrit levels evaluated at test termination. Metabolic endpoints were also evaluated using liver, brain and muscle tissue, and gonads were evaluated histologically. Results indicate that current environmental exposure scenarios may be sufficient to adversely impact the health of wild fish populations. Adult male fish exposed to metformin had significantly reduced whole body weight and condition factor and several male fish from the high-dose metformin had oocytes in their testes. Metformin-exposed fish had altered moisture and lipid (decrease) content in their tissues. Further, brain (increase) and liver (decrease) glycogen were altered in fish exposed to high-dose metformin. To our knowledge, this study constitutes the first effort to understand metformin's effects on a wild small-bodied fish population under environmentally relevant field exposure conditions.

Shelter cleaning of frillfin goby as non-reproductive behaviour

Various animals perform nest cleaning behaviour for breeding and keeping the hygiene of their living environment. Some fishes are also known to clean the nest for breeding and parental care, but it is unclear whether they clean it under non-breeding conditions. This study investigated the shelter cleaning behaviour of frillfin goby (Bathygobius fuscus) during the non-breeding season. All individuals of both males and females removed unknown objects (fishing sinkers) from their shelter, whereas they did not move many sinkers in the feeding area located outside the shelter. Subsequent video observation showed that fish removed sinkers using their tail fin, snout, mouth, and pectoral fins. The results suggest that frillfin goby clean their shelter even under non-breeding conditions. Furthermore, this study found that they can use pectoral fins to move objects, just like other animals use their hands and forelimbs to do so, supporting the developmental relationship between digits and pectoral fins in terms of functionality.

Low doses and lifecycle exposure of waterborne antidepressants in zebrafish model: A survey on sperm traits, reproductive behaviours, and transcriptome responses

Venlafaxine and citalopram have been commonly found in surface water and may disrupt fish reproduction, yet the long-term impact and the underlying mechanism are largely unknown. Here, zebrafish were exposed to 0.1-100 μg/L venlafaxine and citalopram for their entire life cycle from embryo to adult, respectively. After exposure for 180 days, the lowest observable effective concentration (LOEC) of venlafaxine and citalopram to significantly reduce the mean number of egg production in adults were 10 and 1 μg/L, respectively, whereas the fertilization rate displayed no significant changes. Further, we investigated the impacts of venlafaxine and citalopram in a reproductive context, including sperm quality and reproductive behaviour. In contrast, venlafaxine and citalopram exposure did not affect sperm quality but caused a reduction of reproductive behaviour (e.g., mating duration and mating interval) of adults exposed to 1-10 μg/L of the antidepressant. Transcriptomic profiling of the whole ovary revealed that lifecycle venlafaxine and citalopram exposure significantly affected the Na⁺/Cl^- dependent neurotransmitter transporters signaling. Moreover, immune system-mediated ovarian regeneration and creatine metabolism regulated energy metabolism were proposed as the novel mechanism in the observed effects. Taken together, our results highlight the risk of lifecycle venlafaxine and citalopram exposure to fish reproduction and provide novel perspectives for unveiling the mechanism of female reproductive dysfunction.

Levels and effects of antidepressant drugs to aquatic organisms

The use of antidepressants has been increasing globally, resulting in their presence in the aquatic environment, mainly by municipal wastewaters. This fact has aroused concern in the scientific community since these biologically active compounds can affect non-target organisms that have physiological systems regulated by these pharmaceuticals. However, the current knowledge on the toxicological effects of antidepressants on aquatic ecosystems is limited. Considering the increasing consumption pattern, quantification studies and toxicity studies, the present work aimed to review the available literature, published in the last seven years, addressing levels of antidepressants and their metabolites in rivers, surface waters, tap water, and wastewater treatment plants, as well, the effects reported in fish and invertebrates. Overall, the available laboratory studies showed that antidepressants can act at different levels of biological organisation, with detrimental effects at the individual level (e.g., survival, growth, and morphology, behaviour, and reproduction). However, the effects of prolonged exposures to environmentally relevant concentrations of these substances, a more realistic scenario, are unknown. Based on short-term studies, the long-term effects of pharmaceuticals at environmentally relevant concentrations (alone and in the presence of other environmental contaminants) should be studied.

Temperature modulates the impacts of wastewater exposure on the physiology and behaviour of fathead minnow

Municipal wastewater treatment plant (WWTP) effluent is a substantial source of pollution in aquatic habitats that can impact organisms across multiple levels of biological organization. Even though wastewater effluent is discharged continuously all year long, its impacts across seasons, specifically during winter, have largely been neglected in ecotoxicological research. Seasonal differences are of particular interest, as temperature-driven metabolic changes in aquatic organisms can significantly alter their ability to respond to chemical stressors. In this study, we examined the effects of multiple levels of wastewater effluent exposure (0, 25, or 50% treated effluent) on the physiological and behavioural responses of adult fathead minnow (Pimephales promelas) at temperatures simulating either summer (20 °C) or winter (4 °C) conditions. At 20 °C, wastewater exposure posed a metabolic cost to fish, demonstrated by higher standard metabolic rate and was associated with increased haematocrit and a reduction in boldness. In contrast, fish exposed to wastewater at 4 °C experienced no change in metabolic rate but performed fewer social interactions with their conspecifics. Taken together, our results demonstrate that wastewater exposure can lead to metabolic and behavioural disruptions, and such disruptions vary in magnitude and direction depending on temperature. Our findings highlight the importance of studying the interactions between stressors, while also underscoring the importance of research during colder periods of the year to broaden and deepen our understanding of the impacts of wastewater contamination in aquatic ecosystems.

Proximate causes and ultimate effects of common antidepressants, fluoxetine and venlafaxine, on fish behavior

Antidepressant (AD) drugs are widely prescribed for the treatment of psychiatric disorders, including depression and anxiety disorders. The continuous use of ADs causes significant quantities of these bioactive chemicals to enter the aquatic ecosystems mainly through wastewater effluent discharge. This may result in many aquatic organisms being inadvertently affected by these drugs. Fluoxetine (FLX) and venlafaxine (VEN) are currently among the most widely detected ADs in aquatic systems. A growing body of experimental evidence demonstrates that FLX and VEN have a substantial capacity to induce neurotoxicity and cause behavioral dysfunctions in a wide range of teleost species. At the same time, these studies often report seemingly contradictory results that are confounding in nature. Hence, we clearly require comprehensive reviews that attempt to find overarching patterns and establish possible causes for these variable results. This review aims to explore the current state of knowledge regarding the neurobehavioral effects of FLX and VEN on fishes. This study also discusses the potential mechanistic linkage between the neurotoxicity of ADs and behavioral dysfunction and identifies key knowledge gaps and areas for future research.

Antidepressants as Endocrine Disrupting Compounds in Fish

As antidepressant usage by the global population continues to increase, their persistent detection in aquatic habitats from municipal wastewater effluent release has led to concerns of possible impacts on non-target organisms, including fish. These pharmaceuticals have been marketed as mood-altering drugs, specifically targeting the monoaminergic signaling in the brain of humans. However, the monoaminergic systems are highly conserved and involved in the modulation of a multitude of endocrine functions in vertebrates. While most studies exploring possible impact of antidepressants on fish have focused on behavioural perturbations, a smaller spotlight has been placed on the endocrine functions, especially related to reproduction, growth, and the stress response. The purpose of this review is to highlight the possible role of antidepressants as endocrine disruptors in fish. While studies linking the effects of environmentally relevant levels of antidepressant on the endocrine system in fish are sparse, the emerging evidence suggests that early-life exposure to these compounds have the potential to alter the developmental programming of the endocrine system, which could persist as long-term and multigenerational effects in teleosts.

Pharmaceuticals Market, Consumption Trends and Disease Incidence Are Not Driving the Pharmaceutical Research on Water and Wastewater

Pharmaceuticals enhance our quality of life; consequently, their consumption is growing as a result of the need to treat ageing-related and chronic diseases and changes in the clinical practice. The market revenues also show an historic growth worldwide motivated by the increase on the drug demand. However, this positivism on the market is fogged because the discharge of pharmaceuticals and their metabolites into the environment, including water, also increases due to their inappropriate management, treatment and disposal; now, worldwide, this fact is recognized as an environmental concern and human health risk. Intriguingly, researchers have studied the most effective methods for pharmaceutical removal in wastewater; however, the types of pharmaceuticals investigated in most of these studies do not reflect the most produced and consumed pharmaceuticals on the market. Hence, an attempt was done to analyze the pharmaceutical market, drugs consumption trends and the pharmaceutical research interests worldwide. Notwithstanding, the intensive research work done in different pharmaceutical research fronts such as disposal and fate, environmental impacts and concerns, human health risks, removal, degradation and development of treatment technologies, found that such research is not totally aligned with the market trends and consumption patterns. There are other drivers and interests that promote the pharmaceutical research. Thus, this review is an important contribution to those that are interested not only on the pharmaceutical market and drugs consumption, but also on the links, the drivers and interests that motivate and determine the research work on certain groups of pharmaceuticals on water and wastewater.

Environmental level of the antidepressant venlafaxine induces behavioral disorders through cortisol in zebrafish larvae (Danio rerio)

Psychoactive drugs discharged into the environment have different effects on the behavior of vertebrates. The objective of this study was to evaluate the effect of venlafaxine on the behavior of zebrafish, and whether melatonin could reverse the induction of venlafaxine. In this study, a series of venlafaxine concentrations (1 μg/L, 10 μg/L, 100 μg/L) was used to treat zebrafish embryos from 2 hours post-fertilization (hpf) to 5dpf. We found that venlafaxine (1 μg/L) can stimulate the growth of the head area, eye area, and body length of zebrafish. The light-dark test showed that venlafaxine (1 μg/L) could increase the activity of zebrafish larvae. What's more, venlafaxine (1 μg/L) upregulated the expression of steroid regulatory factors including steroidogenic acute regulatory protein (star), cytochrome P450 family member 11A1 (cyp11a1) and 11 β hydroxylase (cyp11b1) by cAMP-pCREB pathway, affecting the function of the steroidogenic cells, which might be involved in the increased cortisol levels in zebrafish larvae. Whereas, melatonin (230 μg/L) restored the altered locomotion behavior induced by venlafaxine and recovered the altered gene expression. Our results demonstrate that venlafaxine at levels detected in the aquatic environment impacts behavior and may compromise the adaptive responses to the environment in zebrafish larvae.

Emotion in animal contests

Emotions encompass cognitive and behavioural responses to reward and punishment. Using contests as a case-study, we propose that short-term emotions underpin animals' assessments, decision-making and behaviour. Equating contest assessments to emotional 'appraisals', we describe how contestants appraise more than resource value and outcome probability. These appraisals elicit the cognition, drive and neurophysiology that governs aggressive behaviour. We discuss how recent contest outcomes induce long-term moods, which impact subsequent contest behaviour. Finally, we distinguish between integral (objectively relevant) and incidental (objectively irrelevant) emotions and moods (affective states). Unlike existing ecological models, our approach predicts that incidental events influence contest dynamics, and that contests become incidental influences themselves, potentially causing maladaptive decision-making. As affective states cross contexts, a more holistic ethology (incorporating emotions and moods) would illuminate animal cognition and behaviour.

Zygotic Venlafaxine Exposure Impacts Behavioral Programming by Disrupting Brain Serotonin in Zebrafish

The antidepressant venlafaxine, a selective serotonin and norepinephrine reuptake inhibitor, is present in surface waters downstream of wastewater treatment plants. We previously showed that zygotic venlafaxine deposition alters larval behavior in zebrafish (Danio rerio), but the mechanisms were unknown. Here we tested the hypothesis that venlafaxine disrupts central serotonergic development, leading to impaired behavioral responses in zebrafish larvae. This was tested by microinjecting embryos with venlafaxine immediately after fertilization and performing spatial distribution of serotonin immunoreactivity, as well as characterizing target genes involved in serotonin turnover in the zebrafish brain. We provide evidence that venlafaxine exposure reduces serotonin immunoreactivity and tyrosine hydroxylase-positive cell populations in specific larval brain regions, and this corresponded with reduced larval activity observed in the drug-exposed group. Lowered serotonin was not due to either reduced synthesis or increased breakdown capacity. However, co-injection of serotonin alongside venlafaxine in embryos recovered brain serotonin immunoreactivity, tyrosine hydroxylase-positive cell populations, and rescued venlafaxine-mediated behavioral changes. Overall, our results demonstrate for the first time that early life exposure to venlafaxine perturbs brain development, which may be due to reduced serotonin, leading to altered larval behavior in zebrafish.

Environmental levels of venlafaxine impact larval behavioural performance in fathead minnows

Venlafaxine, a selective serotonin and norepinephrine reuptake inhibitor, is one of the most abundant antidepressants in municipal wastewater effluents (MWWE). The early life stages are particularly sensitive to contaminant exposure, but few studies have examined whether persistent exposure to venlafaxine impart adverse developmental outcomes. The fathead minnow (Pimephales promelas) is a widely used model for ecotoxicological studies, and this fish is native to Alberta, Canada. We tested the hypothesis that environmental levels of venlafaxine compromises early developmental behavioural performances in fathead minnows. Embryos were exposed to waterborne venlafaxine at either 0, 0.06, 0.33, 0.66, 1.37 or 3 μg L^-1 concentration for 7 days. Environmental levels of venlafaxine did not impact the survival, hatch rate or heart rate of fathead minnow embryos and larvae but reduced the growth of larvae even at concentrations as low as 0.06 μg L^-1. We validated thigmotaxis as a screen for anxiolytic and anxiogenic behaviour in fathead minnow larvae by exposing them to concentrations of ethanol and caffeine, respectively. Behavioural analyses revealed that early developmental exposure to venlafaxine does not alter thigmotaxis but reduced the activity of fathead minnows. The larval behavioural assays reported here for fathead minnow have the potential to be used as screening tools for the risk assessment of neurotoxic contaminants in MWWE. Overall, we demonstrate for the first time that exposure to environmental levels of venlafaxine during the critical early developmental window does not elicit an anxiogenic response but may adversely affect the larval growth performance of fathead minnows.

Chronic exposure to venlafaxine and increased water temperature reversibly alters microRNA in zebrafish gonads (Danio rerio)

MicroRNA (miRNA) are short, non-coding RNA that act by downregulating targeted mRNA transcripts. Only recently have they been used as endpoints in studies of aquatic toxicology. The purpose of this study was to determine the effect of an antidepressant contaminant, venlafaxine (VFX), and increased temperature on specific microRNA levels in zebrafish (Danio rerio) reproductive tissue. Adult zebrafish were exposed to one of four conditions; control, 1 μg/L VFX (VFX), 32 °C (Temp), or 1 μg/L VFX + 32 °C (VFX & Temp) for 21 days. Half of the fish were returned to control conditions for a 21-day recovery period. RT-qPCR was performed to measure relative abundances of several miRNAs known to respond to antidepressant exposure: dre-miR-22b-3p, dre-miR-301a, dre-miR-140-5p, dre-let-7d-5p, dre-miR-210-5p, and dre-miR-457b-5p. After the exposure period, dre-miR-22b-3p and dre-miR-301a showed a significant downregulation in response to all treatments. In contrast, after the recovery period, there were no significant differences in microRNA abundance. These altered microRNA are predicted to target several genes, including phosphofructokinase, and are associated with ovarian pathologies. Combined, we have shown that VFX and increased water temperature alter miRNA abundances in zebrafish reproductive tissue, an effect correlated with a functional stress response and cell cycle dysregulation.

First indication of deleterious impacts in white-seabream larvae (Diplodus sargus) survival and behaviour following acute venlafaxine exposure

Wastewater effluents are teeming with organisms, nutrients and chemical substances which water treatment processes fail to remove. Among these substances, pharmaceuticals such as antidepressants are a frequent occurrence, and have been reported to lead to severe effects in the physiology and behaviour of non-target marine species across taxa. Venlafaxine (VFX) is one of the most consistently prescribed substances for the treatment of human depressive disorders, acting as a serotonin and norepinephrine reuptake inhibitor. In the present study, the potential effects of this antidepressant on the survival and key behaviours (i.e. movement, aggression and foraging) of white seabream (Diplodus sargus) larvae were addressed. Larvae were submitted to an acute exposure of two different VFX treatments (low concentration, 10 µg L^-1; and high concentration, 100 µg L^-1) for a total of 48 h. Sampling took place after 24 and 48 h of exposure. Overall, results showed a significant effect of a two-day exposure to VFX in larvae of D. sargus. Survival was significantly reduced by exposure to a high concentration, but behavioural effects of antidepressant exposure were subtle: i.e. increased attack frequency and temporary modulation of capture success. Further research efforts should be directed towards evaluating the potential chronic effects of antidepressants in marine species, if we are to anticipate possible pressures on natural populations, and effectively advice policymakers towards the investment in new and more efficient methods of wastewater treatments.

Assessing the effects of environmentally relevant concentrations of antidepressant mixtures to fathead minnows exposed over a full life cycle

Antidepressant drugs have been detected in municipal wastewater effluents (MWWEs) at ng/L to low μg/L concentrations. We exposed fathead minnow (Pimephales promelas) over a full lifecycle to a mixture of five antidepressants at concentrations similar to a MWWE (1× AntiD Mix); venlafaxine at 2400 ng/L, citalopram at 240 ng/L, fluoxetine at 90 ng/L, sertraline at 20 ng/L, and bupropion at 90 ng/L, and 10× these concentrations (i.e. 10× AntiD Mix). Mean measured concentrations of venlafaxine, citalopram, fluoxetine, sertraline, and bupropion were 2300, 160, 110, 7 ng/L, and below detection limits, respectively, for the 1× AntiD Mix, and 33,000, 2900, 1000, 210, and 100 ng/L, respectively for the 10× AntiD Mix. During the life-cycle exposure, no significant changes were observed in survival of fathead minnows. When male fish from the exposed treatments reached maturity, their weights were increased compared to control males. There were no significant differences in condition factor, gonadosomatic index, or liver-somatic index in the exposed fish. Exposed fathead minnows produced similar numbers of eggs as control fish, and there were no changes in nest-defense behaviours of male minnows. Egg quality, % fertilization, and % hatching in F1 fry were unaffected by exposure to the antidepressants. Eggs hatched 0.5 d earlier, deformities in fry were 50% lower, and there were transient decreases in length of F1 larvae at 8 days post-hatch in offspring from the treatment with the 10× AntiD Mix. Overall, exposure to the antidepressant mixture at environmentally relevant concentrations (i.e. 1× AntiD Mix) caused no adverse effects in fathead minnows. Exposure to the 10× AntiD Mix increased the weight of adult male minnows and caused subtle effects in F1 offspring. This study is the first to assess sublethal effects in fish exposed to mixtures of antidepressants over a full lifecycle. CAPSULE: No effects were observed in fathead minnow exposed for a lifecycle to antidepressant mixtures at environmentally-relevant concentrations.

Pharmaceutical manufacturing facility discharges can substantially increase the pharmaceutical load to U.S. wastewaters

Discharges from pharmaceutical manufacturing facilities (PMFs) previously have been identified as important sources of pharmaceuticals to the environment. Yet few studies are available to establish the influence of PMFs on the pharmaceutical source contribution to wastewater treatment plants (WWTPs) and waterways at the national scale. Consequently, a national network of 13 WWTPs receiving PMF discharges, six WWTPs with no PMF input, and one WWTP that transitioned through a PMF closure were selected from across the United States to assess the influence of PMF inputs on pharmaceutical loading to WWTPs. Effluent samples were analyzed for 120 pharmaceuticals and pharmaceutical degradates. Of these, 33 pharmaceuticals had concentrations substantially higher in PMF-influenced effluent (maximum 555,000 ng/L) compared to effluent from control sites (maximum 175 ng/L). Concentrations in WWTP receiving PMF input are variable, as discharges from PMFs are episodic, indicating that production activities can vary substantially over relatively short (several months) periods and have the potential to rapidly transition to other pharmaceutical products. Results show that PMFs are an important, national-scale source of pharmaceuticals to the environment.