Fluoxetine Exposure Research Articles

The pharmaceutical pollutant fluoxetine alters reproductive behaviour in a fish independent of predation risk

Pharmaceutical pollutants constitute a major threat to wildlife because of their capacity to induce biological effects at low doses. One such pollutant is the antidepressant fluoxetine, which has been detected in surface waters globally at levels that recent studies suggest can alter physiology and behaviour in aquatic organisms. However, wildlife exposed to pharmaceutical contaminants are typically confronted with multiple stressors simultaneously, including predation risk, which is a particularly important natural stressor that can have direct (e.g. mortality) and indirect (e.g. changed prey behaviour) fitness effects. Accordingly, we investigated potential impacts of environmentally realistic fluoxetine exposure on reproductive behaviour in the guppy (Poecilia reticulata) under predation risk. Specifically, we tested whether fluoxetine exposure altered mating behaviour in male and female guppies in the presence of either a predatory spangled perch (Leiopotherapon unicolor) or a non-predatory rainbowfish (Melanotaenia splendida) control. We found that fluoxetine and the presence of a predatory spangled perch did not interact to affect reproductive behaviour. We also found that, independent of a predatory threat, fluoxetine exposure altered male mating strategy, with males in the high treatment conducting significantly more coercive ‘sneak’ copulations, whereas the number of courtship displays performed was not significantly affected. Moreover, while fluoxetine exposure did not significantly affect the amount of time that males and females spent following one another, we found that females, but not males, followed a potential partner less when in the presence of the predatory fish. Finally, both sexes reacted to the risk of predation by spending less time in close proximity to a predator than a non-predator. In combination, our findings highlight the capacity of fluoxetine to influence processes of sexual selection at field-realistic concentrations and emphasise the importance of considering multiple stressors when assessing impacts of pharmaceutical pollutants on the behaviour of wildlife.

Effects of waterborne exposure to the antidepressant fluoxetine on swimming, shoaling and anxiety behaviours of the mosquitofish Gambusia holbrooki

Chemical pollution from pharmaceuticals is increasingly recognized as a major hazard to the aquatic biota. Among the wide variety of pharmaceuticals, fluoxetine (FLX) is one of the most widely prescribed antidepressants, and therefore, it is frequently identified in the aquatic environment. As FLX is designed to alter human behaviour and many physiological pathways are conserved across vertebrates, this drug may affect the behaviour of fish living in FLX-polluted environments. Here, we exposed groups of female mosquitofish Gambusia holbrooki to waterborne FLX for 14 days, under semi-static conditions with daily renewal of test solutions. Following exposure, we conducted a set of behavioural assays in individual fish, aimed at assessing the effects of FLX on their locomotor activity and behavioural responses. We found that FLX impaired swimming behaviour at high concentrations (25 μg/L and 50 μg/L) but not at low concentrations close to environmental levels (1 μg/L and 5 μg/L). When swimming activity was assessed 5 min after transfer of the focal fish to the testing tank, 50 μg/L FLX was the only concentration showing significant effects. However, when the same trials were performed 24 h later, 25 μg/L FLX turned out to be an effect concentration in addition to 50 μg/L. Interestingly, these concentrations would elicit fish plasma concentrations comprised within the range of human therapeutic doses. When subjected to a light/dark preference test, fish showed tendency to remain less time in the dark area at high FLX concentrations, thus suggesting an anti-anxiety response. Shoaling behaviour was not affected by FLX exposure. Our study contributes to the growing body of literature evaluating the effects of FLX on animal behaviour. Regarding the experimental design used in behavioural testing, our findings suggest that focal fish should be subjected to long habituation periods, namely of at least a few hours, in order to better assess the effects of drug exposure.

Peripartum Fluoxetine Reduces Maternal Trabecular Bone After Weaning and Elevates Mammary Gland Serotonin and PTHrP.

Selective serotonin reuptake inhibitors (SSRIs) have been linked to osteopenia and fracture risk; however, their long-term impact on bone health is not well understood. SSRIs are widely prescribed to pregnant and breastfeeding women who might be at particular risk of bone pathology because lactation is associated with considerable maternal bone loss. We used microCT and molecular approaches to test whether the SSRI fluoxetine, administered to C57BL/6 mice from conception through the end of lactation, causes persistent maternal bone loss. We found that peripartum fluoxetine increases serum calcium and reduces circulating markers of bone formation during lactation but does not affect osteoclastic resorption. Peripartum fluoxetine exposure also enhances mammary gland endocrine function during lactation by increasing synthesis of serotonin and PTHrP, a hormone that liberates calcium for milk synthesis and reduces bone mineral volume. Peripartum fluoxetine exposure reduces the trabecular bone volume fraction at 3 months after weaning. These findings raise new questions about the long-term consequences of peripartum SSRI use on maternal health.

Effect of maternal fluoxetine exposure on lung, heart, and kidney development in rat neonates.

Objective(s):Depression during pregnancy negatively affects fetal development. Fluoxetine as a selective serotonin reuptake inhibitor (SSRIs) is used for treatment of gestational depression. This study is trying to determine the effects of fluoxetine on the renal, heart and lung development.Materials and Methods:Fifteen pregnant rats were treated with fluoxetine at 7 mg/kg from days 0 to 21 of gestation. Immediately after born, heart and kidney samples were evaluated for genes expression and histological assessment. Lung sample were fixed for immunohistochemical study.Results:The gene expression of BMP7 and WNT4 were reduced in the kidney of fluoxetine-treated group (P-value<0.05), but in the heart of both groups no significant difference was found in gene expression (P-value>0.05). Histological assessment showed that the glomeruli of the kidneys in treated group are more primordial compared to control. There was a developmental deficiency in Bowman’s capsule, and the capsular space was not clear. The arrangements of the filaments, the position of the nucleus and cells morphology were normal in the hearts of both groups. Immunohistochemical analysis demonstrated that in the fluoxetine-exposed group HoxB5 is more expressed in the mesenchymal cells, but in the control group the expression is limited to alveolar cells.Conclusion:According to developmental changes in kidney, heart and lung, fluoxetine affects neonatal growth during pregnancy, which may lead to delay of some organs growth. So, it is essential to survey the roles of antidepressant drugs on fatal and neonatal development during pregnancy.

Does fluoxetine exposure affect hypoxia tolerance in the Gulf toadfish, Opsanus beta?

Due to ineffective wastewater treatment technologies, pharmaceuticals such as the selective serotonin reuptake inhibitors (SSRIs)—a common class of antidepressants which inhibit the serotonin transporter (SERT)—can be found in surface waters and marine receiving waters near wastewater effluents. Understanding how exposure to these chemicals might impact non-target organisms, especially combined with other environmental stressors like hypoxia, is essential in order to thoroughly evaluate environmental risk. It was hypothesized that both acute and chronic exposure to the SSRI fluoxetine (FLX) would interfere with the metabolic hypoxia response of the Gulf toadfish, Opsanus beta. Here we demonstrate that acute intraperitoneal treatment with 50 μg g−1 FLX significantly reduces the regulation index, or degree of metabolic regulation, in toadfish. Acute FLX exposure significantly reduced SERT mRNA expression in the first and third gill arches, but mRNA expression was not affected in heart tissues or in the second gill arch. In contrast, the regulation index was unaffected by 14–17 day waterborne FLX exposure to environmentally relevant (0.01 μg L−1) and approximately 1000-fold higher (8.5 μg L−1) concentrations. However, the higher concentration was sufficient to induce a systemic elevation in plasma serotonin concentrations. Chronic FLX exposure did not alter SERT mRNA expression in heart or gill tissues. The results of this study implicate the involvement of 5-HT pathways in hypoxia tolerance but demonstrate that current environmental levels of FLX are insufficient to impair the metabolic hypoxia response in marine fish.

The antidepressant fluoxetine alters mechanisms of pre- and post-copulatory sexual selection in the eastern mosquitofish (Gambusia holbrooki)

Contamination of aquatic habitats with pharmaceuticals is a major environmental concern. Recent studies have detected pharmaceutical pollutants in a wide array of ecosystems and organisms, with many of these contaminants being highly resistant to biodegradation and capable of eliciting sub-lethal effects in non-target species. One such pollutant is fluoxetine, a widely prescribed antidepressant, which is frequently detected in surface waters globally and can alter physiology and behaviour in aquatic organisms. Despite this, relatively little is known about the potential for fluoxetine to disrupt mechanisms of sexual selection. Here, we investigate the impacts of 30-day exposure to two environmentally realistic levels of fluoxetine (low and high) on mechanisms of pre- and post-copulatory sexual selection in the eastern mosquitofish (Gambusia holbrooki). We tested 1) male mating behaviour in the absence or presence of a competitor male, and 2) sperm quality and quantity. We found that high-fluoxetine exposure increased male copulatory behaviour in the absence of a competitor, while no effect was detected under male-male competition. Further, fluoxetine exposure at both concentrations increased total sperm count relative to males from the control group, while no significant change in sperm quality was observed. Lastly, low-fluoxetine males showed a significant reduction in condition index (mass relative to length). Our study is the first to show altered mechanisms of both pre- and post-copulatory sexual selection in an aquatic species resulting from environmentally realistic fluoxetine exposure, highlighting the capacity of pharmaceutical pollution to interfere with sensitive reproductive processes in wildlife.

Fluoxetine modulates the transcription of genes involved in serotonin, dopamine and adrenergic signalling in zebrafish embryos

Neurotransmitters pathways in fish and mammals are phylogenetically conserved. Therefore, the environmental presence of psychopharmaceuticals, such as fluoxetine (FLU), are likely to interact with fish serotonergic, dopaminergic and adrenergic systems, affecting their response and associated biological functions. Hence, the present work aimed at evaluating the effects of FLU in the transcription of genes involved in serotonin, dopamine and adrenergic transporters and receptors signalling in early stages of Danio rerio development. Embryos (1 hpf) were exposed for 80 h to different concentrations of FLU (0.0015, 0.05, 0.1, 0.5 and 0.8 μM) and mRNA levels of sert, 5-ht1a, 5-ht2c, dat, drd1b, drd2b, net, adra2a, adra2b, adra2c, vmat and mao were evaluated. A sensorimotor reflex assay was also performed demonstrating a significant decrease in tail reflex at 0.1 and 0.5 μM. The transcription levels of serotonergic and dopaminergic transporters (sert and dat) and vmat were down-regulated at environmentally relevant concentration (0.0015 μM). Receptors 5-ht2c, drd2b adra2b and adra2c mRNA levels also displayed a down regulation pattern after FLU exposure. In conclusion, this study demonstrated the interaction of FLU with the neurotransmission system at environmentally relevant concentrations by changing transcription patterns. Therefore, given the importance of these signalling pathways it is possible that their disruption can ultimately disturb the escape behaviour and biological functions in fish. Hence, evaluating the presence of this psychopharmaceutical in the aquatic environment should be implemented in future monitoring programmes.

Perinatal fluoxetine prevents the effect of pre-gestational maternal stress on 5-HT in the PFC, but maternal stress has enduring effects on mPFC synaptic structure in offspring

Maternal affective disorders are frequently treated with selective serotonin reuptake inhibitor medications (SSRIs); with up to 10% of women being prescribed these medications during pregnancy. Infant development depends on the early serotonergic environment, which is altered by perinatal SSRIs, raising concern about how these medications affect neural outcomes. While clinical and preclinical research suggests an impact of SSRIs on the developing brain, more research is needed to determine the effects on neuroplasticity, the serotonergic system, and the hypothalamic-pituitary-adrenal axis in neural regions mediating behavior. The current work investigated the effects of the SSRI, fluoxetine, on the serotonergic system in the prefrontal cortex (PFC) during pre-adolescence, and changes to synaptic markers and glucocorticoid receptor density in the cingulate cortex (medial PFC) of pre-adolescent and adult Sprague-Dawley male and female rats. To model aspects of Perinatal Depression and maternal anxiety, pre-gestational maternal stress was used resulting in male and female offspring from 4 groups: 1) control, 2) perinatal fluoxetine exposed, 3) pre-gestational maternal stress exposed, and 4) pre-gestational maternal stress + fluoxetine. Perinatal fluoxetine prevented the effects of maternal stress on 5-HT levels and 5-HT turnover ratio in the PFC of pre-adolescent offspring, particularly in females. However, pre-gestational stress reduced synaptophysin and PSD-95 densities in the cingulate cortex, effects that were more pronounced in males. Interestingly, perinatal fluoxetine exposure reduced GR density in adult males in this same brain area. Together, results show differential effects of perinatal SSRIs and pre-gestational maternal stress on neurodevelopment in the PFC of males and females.

Prozac in the water: Chronic fluoxetine exposure and predation risk interact to shape behaviors in an estuarine crab.

Predators exert considerable top‐down pressure on ecosystems by directly consuming prey or indirectly influencing their foraging behaviors and habitat use. Prey is, therefore, forced to balance predation risk with resource reward. A growing list of anthropogenic stressors such as rising temperatures and ocean acidification has been shown to influence prey risk behaviors and subsequently alter important ecosystem processes. Yet, limited attention has been paid to the effects of chronic pharmaceutical exposure on risk behavior or as an ecological stressor, despite widespread detection and persistence of these contaminants in aquatic environments. In the laboratory, we simulated estuarine conditions of the shore crab, Hemigrapsus oregonensis, and investigated whether chronic exposure (60 days) to field‐detected concentrations (0, 3, and 30 ng/L) of the antidepressant fluoxetine affected diurnal and nocturnal risk behaviors in the presence of a predator, Cancer productus. We found that exposure to fluoxetine influenced both diurnal and nocturnal prey risk behaviors by increasing foraging and locomotor activity in the presence of predators, particularly during the day when these crabs normally stay hidden. Crabs exposed to fluoxetine were also more aggressive, with a higher frequency of agonistic interactions and increased mortality due to conflicts with conspecifics. These results suggest that exposure to field‐detected concentrations of fluoxetine may alter the trade‐off between resource acquisition and predation risk among crabs in estuaries. This fills an important data gap, highlighting how intra‐ and interspecific behaviors are altered by exposure to field concentrations of pharmaceuticals; such data more explicitly identify potential ecological impacts of emerging contaminants on aquatic ecosystems and can aid water quality management.

Fluoxetine administration during adolescence attenuates cognitive and synaptic deficits in adult 3×TgAD mice

Fluoxetine (FLX) has broad neurobiological functions and neuroprotective effects; however, the preventive effects of FLX on cognitive impairments in Alzheimer's disease (AD) have not been reported. Here, we studied whether adolescent administration of fluoxetine can prevent memory deficits in AD transgenic mice that harbour PS1m146v, APPswe and TauP301L mutations (3 × TgAD). FLX was applied through peritoneal injection to the mice at postnatal day 35 (p35) for 15 consecutive days, and the effects of FLX were observed at 6-month. We found that adolescent administration of FLX improved learning and memory abilities in 6-month-old 3 × TgAD mice. FLX exposure also increased the sizes of the hippocampal CA1, dentate gyrus (DG) and extensive cortex regions, with increased numbers of neurons and higher dendritic spine density. Meanwhile, the synaptic plasticity of neurons in the hippocampus was remodelled, and the expression levels of synaptic-related proteins were increased along with activation of the cyclic AMP response element-binding (CREB) protein/brain-derived neurotrophic factor (BDNF) signalling pathway. Finally, we found that FLX effectively prevented the increase of beta-amyloid (Aβ) levels. These data suggest that adolescent administration of the antidepressant drug FLX can efficiently preserve cognitive functions and improve pathologies in 3×Tg AD mice.

Assessing biological effects of fluoxetine in developing zebrafish embryos using gas chromatography-mass spectrometry based metabolomics

Continuous low-dose exposure of pharmaceutically active compounds (PhACs) in aquatic ecosystems is a concern worldwide. In this study, we utilized a gas chromatography mass spectrometry (GC-MS) based metabolomics approach to assess endogenous metabolite changes in developing zebrafish embryos exposed to different concentrations of the widely used antidepressant, fluoxetine. Embryos were exposed from 2 h post fertilization (hpf) until 96 hpf. Using the Fiehn GC-MS library, a total of 31 metabolites were positively identified in embryos. Statistical analyses revealed significant dysregulation of 11 metabolites in fluoxetine exposed embryos. Metabolite classes that were significantly altered included, amino acids, monosaccharides, glycerophosphates, fatty acids, carboxylic acid derivatives and sugars. Concentrations of amino acids, maltose, d-malic acid, 3-phosphoglycerate and d-glucose were significantly reduced in exposed embryos. Conversely, concentrations of citric acid were in some cases significantly elevated in exposed embryos. Metabolic pathway analysis revealed perturbation of five main pathways, including (i) alanine, aspartate and glutamate metabolism, (ii) phenylalanine, tyrosine and tryptophan biosynthesis, (iii) phenylalanine metabolism. (iv) tyrosine metabolism and (v) starch and sucrose metabolism. The results indicate fluoxetine exposure causes perturbation of energy and amino acid metabolism, which may adversely impact embryogenesis due to depletion of energy reserves during this period. Also, the observed alterations in aspartic acid, phenylalanine and tyrosine in fluoxetine exposed embryos suggests potential disruption of normal neurobehavioral and liver function. The results further demonstrate that GC-MS based metabolomics is an effective approach for assessing toxicodynamics and threshold effect levels of environmental pollutants in aquatic organisms.

Differential Peripheral Proteomic Biosignature of Fluoxetine Response in a Mouse Model of Anxiety/Depression

The incorporation of peripheral biomarkers in the treatment of major depressive disorders (MDD) could improve the efficiency of treatments and increase remission rate. Peripheral blood mononuclear cells (PBMCs) represent an attractive biological substrate allowing the identification of a drug response signature. Using a proteomic approach with high-resolution mass spectrometry, the present study aimed to identify a biosignature of antidepressant response (fluoxetine, a Selective Serotonin Reuptake Inhibitor) in PBMCs in a mouse model of anxiety/depression. Following determination of an emotionality score, using complementary behavioral analysis of anxiety/depression across three different tests (Elevated Plus Maze, Novelty Suppressed Feeding, Splash Test), we showed that a 4-week corticosterone treatment (35 μg/ml, CORT model) in C57BL/6NTac male mice induced an anxiety/depressive-like behavior. Then, chronic fluoxetine treatment (18 mg/kg/day for 28 days in the drinking water) reduced corticosterone-induced increase in emotional behavior. However, among 46 fluoxetine-treated mice, only 30 of them presented a 50% decrease in emotionality score, defining fluoxetine responders (CORT/Flx-R). To determine a peripheral biological signature of fluoxetine response, proteomic analysis was performed from PBMCs isolated from the “most” affected corticosterone/vehicle (CORT/V), corticosterone/fluoxetine responders and non-responders (CORT/Flx-NR) animals. In comparison to CORT/V, a total of 263 proteins were differently expressed after fluoxetine exposure. Expression profile of these proteins showed a strong similarity between CORT/Flx-R and CORT/Flx-NR (R = 0.827, p < 1e-7). Direct comparison of CORT/Flx-R and CORT/Flx-NR groups revealed 100 differently expressed proteins, representing a combination of markers associated either with the maintenance of animals in a refractory state, or associated with behavioral improvement. Finally, 19 proteins showed a differential direction of expression between CORT/Flx-R and CORT/Flx-NR that drove them away from the CORT-treated profile. Among them, eight upregulated proteins (RPN2, HSPA9, NPTN, AP2B1, UQCRC2, RACK-1, TOLLIP) and one downregulated protein, TLN2, were previously associated with MDD or antidepressant drug response in the literature. Future preclinical studies will be required to validate whether proteomic changes observed in PBMCs from CORT/Flx-R mice mirror biological changes in brain tissues.

Endocrine disrupting effects of waterborne fluoxetine exposure on the reproductive axis of female goldfish, Carassius auratus

Evidence suggests that pharmaceuticals and personal care products reach urban watersheds, bioconcentrate in fish, and potentially disrupt physiological homeostasis. These impairments often affect hormone functions. Selective serotonin reuptake inhibitors (SRRIs) are increasingly studied with regards to their endocrine disrupting effects on teleost physiological processes, including reproduction. To examine whether FLX effects on the endocrine regulation of reproductive physiology in goldfish are sex-specific, we exposed sexually recrudescent female goldfish to two waterborne concentrations of FLX (0.54μg/L and 54μg/L) using an experimental design previously used for sexually mature male goldfish. To evaluate possible endocrine disrupting effects, we quantified the gonadosomatic index, circulating hormone concentrations (luteinizing hormone, LH; growth hormone, GH; 17-β estradiol, E2; and testosterone, T), and the expression of isotocin and vasotocin in the telencephalon, gonadotropin subunits and GH in the pituitary, and gonadotropin receptors, GH receptors, and aromatase in the ovary. Female goldfish exposed to 0.54μg/L FLX exhibited a significant decrease in circulating E2, and conversely, a significant increase in circulating LH and ovarian aromatase mRNA levels, suggesting disruption of E2-mediated feedback on LH release. These results, when compared with those previously observed in males, reveal that waterborne exposure to environmentally relevant levels of FLX sex-specifically disrupts the reproductive endocrine axis in goldfish, characterized by a decrease in E2 in females, and conversely, estrogen-like effects in males. These data emphasize the importance of studying the effect of endocrine disrupting chemicals on both sexes.

Neonatal fluoxetine exposure modulates serotonergic neurotransmission and disturb inhibitory action of serotonin on food intake

The neurotransmitter serotonin (5-HT) acts as an important regulator of the critical neurodevelopmental processes and thus alterations in 5-HT signaling early promotes permanent structural and functional changes in brain. The selective serotonin reuptake inhibitors (SSRIs), as fluoxetine and citalopram, blocking serotonin transporter (SERT) at the presynaptic neuron, which regulates extracellular 5-HT levels. Evidence suggests that the exposure to SSRIs in the neurodevelopmental period may alters 5-HT signaling sensitivity on food intake control. The aim of the present study was to evaluate the effects of neonatal exposure to fluoxetine on molecular and cellular components of the serotonergic system and food intake control in young animals. Methods: The animals were divided according to experimental manipulation, Fluoxetine Group (FG): male pups received application of fluoxetine (10 mg/kg, 10 μL/g) and Saline Group (SG): male pups received saline application (0.9% NaCl, 10 μL/g), both throughout lactation (PND1–PND21). They evaluated body weight, food intake, SERT gene and protein expression, serotonin content in the hypothalamus. The neonatal exposure to fluoxetine promoted reduction in body weight, disturb the serotonin hypophagic response, and increase the serotonin and SERT hypothalamic in young animals. We conclude that the changes of components of the serotonergic system by neonatal exposure to fluoxetine may be responsible for disturb the inhibitory action of serotonin on food intake.

Sex-dependent effects of maternal corticosterone and SSRI treatment on hippocampal neurogenesis across development

BackgroundPostpartum depression affects approximately 15% of mothers and represents a form of early life adversity for developing offspring. Postpartum depression can be treated with prescription antidepressants like fluoxetine (FLX). However, FLX can remain active in breast milk, raising concerns about the consequences of neonatal FLX exposure. The hippocampus is highly sensitive to developmental stress, and males and females respond differently to stress at many endpoints, including hippocampal plasticity. However, it is unclear how developmental exposure to FLX alters the trajectory of hippocampal development. The goal of this study was to examine the long-term effects of maternal postpartum corticosterone (CORT, a model of postpartum depression) and concurrent FLX on hippocampal neurogenesis in male and female offspring.MethodsFemale Sprague-Dawley rat dams were treated daily with either CORT or oil and FLX or saline from postpartum days 2–23. Offspring were perfused on postnatal day 31 (pre-adolescent), postnatal day 42 (adolescent), and postnatal day 69 (adult). Tissue was processed for doublecortin (DCX), an endogenous marker of immature neurons, in the dorsal and ventral hippocampus.ResultsMaternal postpartum CORT reduced density of DCX-expressing cells in the dorsal hippocampus of pre-adolescent males and increased it in adolescent males, suggesting that postpartum CORT exposure disrupted the typical progression of the density of DCX-expressing cells. Further, among offspring of oil-treated dams, pre-adolescent males had greater density of DCX-expressing cells than pre-adolescent females, and maternal postpartum CORT prevented this sex difference. In pre-adolescent females, maternal postpartum FLX decreased the density of DCX-expressing cells in the dorsal hippocampus compared to saline. As expected, maternal CORT reduced the density of DCX-expressing cells in adult female, but not male, offspring. The combination of maternal postpartum CORT/FLX diminished density of DCX-expressing cells in dorsal hippocampus regardless of sex or age.ConclusionsThese findings reveal how modeling treatment of postpartum depression with FLX alters hippocampal neurogenesis in developing offspring differently depending on sex, predominantly in the dorsal dentate gyrus and earlier in life.

Behavioural outcomes of adult female offspring following maternal stress and perinatal fluoxetine exposure

Depression, anxiety, and stress are common in pregnant women. One of the primary pharmacological treatments for anxiety and depression is the antidepressant fluoxetine (Flx). Maternal stress, depression, and Flx exposure are known to effect neurodevelopment of the offspring, however, their combined effects have been scarcely studied, especially in female offspring. The present study investigated the combined effects of maternal stress during pregnancy and perinatal exposure to Flx on the behaviour of female mice as adults. MethodsMouse dams were exposed to either chronic unpredictable stress (embryonic (E) day 7 to E18), or FLX (E15- postnatal day 12), or a combination of stress and FLX or left untreated. At two months of age, the female offspring went through a comprehensive behavioural test battery. ResultsMaternal stress led to increased activity and alterations of prepulse inhibition in the adult female offspring. Maternal treatment with Flx had a potentially beneficial effect on spatial memory. The combination of prenatal stress and perinatal Flx exposure did not interact in their effects. These results suggest that gestational Flx exposure may have a limited negative impact on female offspring.

Bioconcentration of the antidepressant fluoxetine and its effects on the physiological and biochemical status in Daphnia magna

The aim of this study was to evaluate the bioconcentration potential of fluoxetine and its biological effects in Daphnia magna. After 48h of waterborne exposure, the bioconcentration of fluoxetine in D. magna was determined to be 460.61 and 174.41Lkg−1 for nominal exposure concentrations of 0.5 and 5µgL−1, respectively. Moreover, various biological endpoints, including physiological responses (filtration and ingestion rates), enzymatic biomarkers related to neurotoxicity [acetylcholinesterase (AChE)] and antioxidant defense [superoxide dismutase (SOD)], and an oxidative stress damage marker [malondialdehyde (MDA)], were assessed. Fluoxetine exposure increased the filtration rate of daphnia, while the ingestion rate was not obviously modified. AChE activity was significantly inhibited, highlighting the neurotoxicity of fluoxetine on D. magna. However, with some alterations in the SOD activity and MDA content, no obvious oxidative damage was observed in D. magna exposed to fluoxetine at the tested concentrations. These results indicate that fluoxetine can be accumulated and consequently induce physiological and biochemical perturbations in D. magna.

An evaluation of behavioural endpoints: The pharmaceutical pollutant fluoxetine decreases aggression across multiple contexts in round goby (Neogobius melanostomus)

Fluoxetine (Prozac™) is designed to alter human behaviour; however, because many physiological pathways are conserved across vertebrates, this drug may affect the behaviour of fish living in fluoxetine-polluted environments. Although a number of studies have used behaviour to document the sub-lethal effects of fluoxetine, the repeatability of these effects across experiments, across behavioural contexts, and over different exposure durations are rarely considered. Here, we conducted two experiments and assessed how fluoxetine exposure affected a range of fitness-related behaviours in wild round goby (Neogobius melanostomus). We found that fluoxetine impacts round goby behaviour at high (40 μg/l) doses, but not at environmentally relevant low doses (1 μg/l). In both experiments, an acute 3-day exposure to fluoxetine reduced round goby aggression in multiple behavioural contexts, but had no detectable effect on overall activity or social affiliative behaviour. While a chronic 28-day exposure to fluoxetine exposure still reduced aggression, this reduction was only detectable in one behavioural context. Our findings demonstrate the importance of repeated behavioural testing (both between and within experiments) and contribute to a growing body of literature evaluating the effects of fluoxetine and other pharmaceuticals on animal behaviour.

The psychoactive pollutant fluoxetine compromises antipredator behaviour in fish

Pharmaceuticals are increasingly being detected in aquatic ecosystems worldwide. Particularly concerning are pharmaceutical pollutants that can adversely impact exposed wildlife, even at extremely low concentrations. One such contaminant is the widely prescribed antidepressant fluoxetine, which can disrupt neurotransmission and behavioural pathways in wildlife. Despite this, relatively limited research has addressed the behavioural impacts of fluoxetine at ecologically realistic exposure concentrations. Here, we show that 28-day fluoxetine exposure at two ecologically relevant dosages—one representing low surface water concentrations and another representing high effluent flow concentrations—alters antipredator behaviour in Eastern mosquitofish (Gambusia holbrooki). We found that fluoxetine exposure at the lower dosage resulted in increased activity levels irrespective of the presence or absence of a predatory dragonfly nymph (Hemianax papuensis). Additionally, irrespective of exposure concentration, fluoxetine-exposed fish entered the predator ‘strike zone’ more rapidly. In a separate experiment, fluoxetine exposure reduced mosquitofish freezing behaviour—a common antipredator strategy—following a simulated predator strike, although, in females, this reduction in behaviour was seen only at the lower dosage. Together, our findings suggest that fluoxetine can cause both non-monotonic and sex-dependent shifts in behaviour. Further, they demonstrate that exposure to fluoxetine at environmentally realistic concentrations can alter antipredator behaviour, with important repercussions for organismal fitness.

Fluoxetine modulates sex steroid levels in vitro.

Background and aimsSelective serotonin reuptake inhibitors (SSRIs) are antidepressants increasingly prescribed against depression during and after pregnancy. However, these compounds cross the placenta and are found in breast milk, thus reaching, and possibly affecting, the fetus and infant during critical developmental stages. Fluoxetine (FLX), a widely used SSRI, can interfere with estrogen signaling, which is important for the development of female sex organs and certain brain areas, among others. Interference with estrogen signaling can take place on different levels, e.g., by affecting receptor activity or hormone levels. FLX has previously been shown to induce estrogen receptor-dependent transcription in vitro at high concentrations. In this study we set out to assess effects of FLX on estradiol levels in vitro.MethodsFLX was tested using the OECD recommended H295R model, a human adrenocortical carcinoma cell line that is able to produce all steroid hormones found in the gonads and adrenal glands, including estradiol and testosterone. H295R cells were incubated with different doses of FLX for 48h. Subsequently, concentrations of these two steroids were measured in cell culture medium after FLX exposure, using liquid chromatography coupled with tandem mass spectrometry. Aromatase mRNA expression was assessed using qPCR.ResultsFluoxetine significantly increased estradiol secretion in H295R cells after a 48h exposure at low, submicromolar concentrations, but showed no effects on testosterone levels or aromatase mRNA expression.ConclusionFluoxetine has the potential to interfere with estrogenic signaling by increasing estradiol secretion at low concentrations, which are relevant for fetal and adult human exposure.