Sub-chronic exposure to paroxetine disrupts ecologically relevant behaviours in fish

The functional conservation of important selective serotonin reuptake inhibitor (SSRI) targets in non-target organisms raises concerns about their potential adverse effects on the ecosystems. Although the environmental levels of SSRIs like paroxetine (PAR) have risen, the knowledge regarding the effects of long-term exposure to PAR is limited. This study investigated the impact of sub-chronic exposure (21 days) to two sub-lethal concentrations of PAR (40 and 400 μg/L) on the behaviour of adult zebrafish in different scenarios: basal activity (under dark and light conditions), stress response (evoked by sudden light transitions) and stress response recovery. A new framework was employed for the integrative study of fish's swimming performance based on their innate ability to respond to light shifts. Several swimming-associated parameters (e.g., total swimming distance, time of inactivity, swimming angles) and thigmotaxis were monitored for an integrated analysis in each scenario. Data revealed reduced swimming activity, impaired behavioural response to stress and alterations in stress recovery of PAR-exposed fish. An anxiolytic effect was particularly noticeable in fish basal swimming activity in the dark at 400 μg/L and in the behavioural response to stress (from dark to light) and stress recovery (from light to dark) for organisms exposed to 40 μg/L. The detected PAR-induced behavioural modifications suggest a disruption of brain glucocorticoid signalling that may have implications at the individual level (e.g., changing behavioural responses to predators), with potential repercussions on the population and community levels. Therefore, the applied protocol proved sensitive in detecting behavioural changes induced by PAR.

Are early and young life stages of fish affected by paroxetine? A case study with Danio rerio

Paroxetine (PAR) is a selective serotonin reuptake inhibitor (SSRI) antidepressant increasingly detected in surface waters worldwide. Its environmental presence raises concerns about the potential detrimental effects on non-target organisms. Thus, this study aimed to increase knowledge on PAR's potential environmental impacts, assessing the effects of commercial formulation (PAR-c) and active ingredient (PAR-a) on fish. Therefore, the short-term exposure effects of PAR-c and PAR-a were assessed on zebrafish (Danio rerio) embryos/larvae to determine the most toxic formulation [through median lethal (LC50) and effective concentrations (EC50)]. PAR-c and PAR-a induced morphological abnormalities (scoliosis) in a dose-dependent manner from 96 hours post-fertilization onwards, suggesting the involvement of a fully functional biotransformation system. As PAR-c exhibited higher toxicity, it was selected to be tested in the subsequent stage (juvenile stage), which was more sensitive (lower LC50). PAR-c significantly decreased fish swimming activity and disrupted fish stress response. Overall, the results highlight the ability of PAR-c to adversely affect fish swimming performance, an effect that persisted even after exposure ceases (21-day depuration), suggesting that PAR-c may impair individual fitness.

An overall assessment of the effects of antidepressant paroxetine on aquatic organisms and human cells

Paroxetine (PRX) is one of the most used antidepressants and an emerging contaminant with potential harmful effects to the environment and human health. The present study investigates in detail the toxic potential of PRX using a battery of bioassays on fresh- and marine species, marine bacteria, and human lymphocytes. All the tested organisms and human lymphocytes were exposed at concentrations ranging from μg L^-1 to mg L^-1. It was found that PRX can cause toxic effects to aquatic organisms at environmental relevant concentrations (μg L^-1 level). A significant effect of PRX was observed in all tested algal species especially at the first 24 h. However, differences in responses and sensitivities among the tested algal species were observed. The most sensitive organism was found to be Dunaliella tertiolecta with IC₅₀ = 0.092 mg L^-1 (72 h). In the case of Aliivibrio fischeri, EC₅₀ values were determined to be 16.65, 14.31 and 14.41 mg L^-1 for 5, 15 and 30 min of exposure, respectively. PRX also induced cytotoxic and genotoxic effects in human lymphocytes. A dose-dependent increase in micronucleus frequencies was occurred at all tested concentrations with a statistically significant increase in micronucleus frequencies at the medium to high PRX tested concentrations. The findings of the present study expand the available toxicity profile of PRX on aquatic organisms and the knowledge about the potential risk of PRX to induce genotoxic effects in cultured human lymphocytes.

Effects of the antidepressant paroxetine on migratory behaviour of meiobenthic nematodes: Computational and open experimental microcosm approach

An open experimental setup was established in order to explore the toxic effects of the antidepressant paroxetine on meiobenthic nematodes. Three types of microcosms made from polyvinyl chloride tubes, each comprising two sediments compartments (upper and lower), were used in a laboratory experiment for 15 days. The experimental setup targeted the migratory behaviour of the nematofauna from the above compartments, which were exposed to paroxetine (0.4 and 40 μg.l^-1), towards below compartments. The univariate indices significantly decrease in the contaminated compartments compared to controls. Multivariate analyses revealed also significant taxonomic dissimilarities between contaminated and uncontaminated compartments. Furthermore, SIMPER functional outcomes highlighted a significant decrease in 2A feeding groups, 'co' tail shape, 1-2 mm interval length, 'cr' amphid shape, and c-p2 life history in contaminated compartments. Computational approach showed that paroxetine bound GLD-3 and SDP with high affinities, which together with molecular interactions and toxicokinetics satisfactorily explain the experimental results.

Effect of paroxetine on intestinal motility in the presence of ondansetron

Chemotherapy, radiotherapy, surgery and depression are the conditions that run in parallel fashions. All these conditions cause the release of an increased amount of serotonin in the body. Serotonin acts on these 5HT3 receptors and causes nausea and vomiting. Ondansetron acts by blocking serotonin from acting on the receptors and thus is useful in decreasing episodes of nausea and vomiting but when used concomitantly with SSRIs (selective serotonin reuptake inhibitors) as cancer patient also suffered from depression. This combination tends to decrease the efficacy of ondansetron. The present study was carried out to observe the modulatory role of ondansetron on ileal smooth muscle motility in vitro. Experiments were performed in four groups (n=6) and ileal smooth muscle activity was recorded on the power lab (USA). The effects of increasing concentrations of serotonin, ondansetron and paroxetine alone were observed. In the fourth group effects of paroxetine in the presence of fixed concentration (1ml) of ondansetron (10^-6M) was observed. The maximum response obtained by serotonin served as a control for our study (100%). Paroxetine response on intestinal motility was completely blocked in the presence of ondansetron. Our findings hence, reinforce the hypothesis that paroxetine decreases the antiemetic activity of serotonin antagonist ondansetron, by super sensitization of serotonergic receptors resulting in an increased incidence of nausea and vomiting in cancer patient despite adequate antiemetic prophylaxis.

Impact of selective serotonin reuptake inhibitors on neural crest stem cell formation

The use of antidepressants in pregnant women is rising, with rates up to 7.5% in the United States. Selective serotonin reuptake inhibitors (SSRIs) are currently the most common antidepressant prescribed to pregnant women. The teratogenic effects of SSRI exposure are debated because of discrepancies in epidemiological studies. As an alternative to epidemiological and animal studies, human embryonic stem cell research (hESC) provides a human-based experimental model to examine the risks of prenatal SSRI exposure. Neural crest stem cells (NCSCs) play an important role in craniofacial and cardiac development as precursors to craniofacial bones and heart septa. This study examines the effects of paroxetine (Paxil) and sertraline (Zoloft) exposure on proliferation, migration, and AP-2α protein expression of NCSC in vitro. hESCs were exposed to paroxetine and sertraline at three concentrations while undergoing directed differentiation into NCSCs. Our results indicate exposure to paroxetine significantly increased proliferation, migration, and AP-2α protein expression in NCSCs. Exposure to sertraline significantly decreased proliferation and significantly increased AP-2α protein expression in NCSC. This evidence suggests paroxetine and sertraline alter normal NCSC behavior and may thereby disrupt cardiac and craniofacial development.

Exposure to SSRI-type antidepressants increases righting time in the marine snail Ilyanassa obsoleta

Exposure to human antidepressants has been shown to disrupt locomotion and other foot-mediated mechanisms in aquatic snails. We tested the effect of three selective serotonin reuptake inhibitor (SSRI)- and one selective serotonin-norepinephrine reuptake inhibitor (SNRI)-type antidepressants on the righting response in the marine snail, Ilyanassa obsoleta. All four antidepressants (fluoxetine, sertraline, paroxetine, venlafaxine) significantly increased righting time compared with controls with an exposure time as short as 1 h. Dose responses were nonmonotonic with effects seen mainly at the lowest exposure concentrations and shortest duration. The lowest concentration to show an effect was 3.45 μg/L fluoxetine with a 2-h exposure period and is about 3.71 times higher than environmental concentrations. Our results highlight rapid disruption of another foot-mediated behavior in aquatic snails by SSRI-type antidepressants. We discuss these and other reported nonmonotonic dose responses caused by antidepressants in terms of the various possible physiological mechanisms of action in nontarget aquatic species.

Paroxetine-induced apoptosis in human osteosarcoma cells: activation of p38 MAP kinase and caspase-3 pathways without involvement of [Ca2+]i elevation

Selective serotonin reuptake inhibitors (SSRIs), a group of antidepressants, are generally used for treatment of various mood and anxiety disorders. There has been much research showing the anti-tumor and cytotoxic activities of some antidepressants; but the detailed mechanisms were unclear. In cultured human osteosarcoma cells (MG63), paroxetine reduced cell viability in a concentration- and time-dependent manner. Paroxetine caused apoptosis as assessed by propidium iodide-stained cells and increased caspase-3 activation. Although immunoblotting data revealed that paroxetine could activate the phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK), only SB203580 (a p38 MAPK inhibitor) partially prevented cells from apoptosis. Paroxetine also induced [Ca(2+)](i) increases which involved the mobilization of intracellular Ca(2+) stored in the endoplasmic reticulum and Ca(2+) influx from extracellular medium. However, pretreatment with BAPTA/AM, a Ca(2+) chelator, to prevent paroxetine-induced [Ca(2+)](i) increases did not protect cells from death. The results suggest that in MG63 cells, paroxetine caused Ca(2+)-independent apoptosis via inducing p38 MAPK-associated caspase-3 activation.

DA-8159 reverses selective serotonin reuptake inhibitor-induced erectile dysfunction in rats

OBJECTIVES

To assess the efficacy of the phosphodiesterase 5 inhibitor, DA-8159, in selective serotonin reuptake inhibitor (SSRI)-induced rat erectile dysfunction model by measuring intracavernous pressure (ICP).

METHODS

Erectile dysfunction was induced by oral administration of either paroxetine or fluoxetine in rats. The changes in ICP and mean arterial pressure (MAP) were simultaneously recorded throughout electrostimulation of the cavernous nerve with 2 or 10 Hz after intravenous injection of DA-8159 (1 mg/kg). Statistical analysis was performed on the ICP/MAP ratio and the area under the curve of the ICP/MAP ratio.

RESULTS

Although the reduction in the ICP responses after acute paroxetine or fluoxetine administration was statistically significant, the electrical stimulation of the cavernous nerve induced a statistically significant, frequency-dependent increase in the ICP/MAP ratio after DA-8159 administration. The differences in the ICP/MAP ratio and corresponding area under the curve values from the SSRI-treated group were statistically significant.

CONCLUSIONS

The results of the present study have demonstrated that DA-8159 reverses the decrease in ICP induced by SSRI treatment, suggesting that DA-8159 may be a potential therapeutic agent for the treatment of erectile dysfunction associated with the use of SSRIs.

Acute and chronic toxicity of five selective serotonin reuptake inhibitors in Ceriodaphnia dubia

Contamination of surface waters by pharmaceutical chemicals has raised concern among environmental scientists because of the potential for negative effects on aquatic organisms. Of particular importance are pharmaceutical compounds that affect the nervous or endocrine systems because effects on aquatic organisms are possible at low environmental concentrations. Selective serotonin reuptake inhibitors (SSRIs) are drugs used to treat clinical depression in humans, and have been detected in low concentrations in surface waters. In this investigation, the acute and chronic toxicity of five SSRIs (fluoxetine, Prozac; fluvoxamine, Luvox; paroxetine, Paxil; citalopram, Celexa; and sertraline, Zoloft) were evaluated in the daphnid Ceriodaphnia dubia. For each SSRI, the 48-h median lethal concentration (LC50) was determined in three static tests with neonate C. dubia, and chronic (8-d) tests were conducted to determine no-observable-effect concentrations (NOEC) and lowest-observable-effect concentrations (LOEC) for reproduction endpoints. The 48-h LC50 for the SSRIs ranged from 0.12 to 3.90 mg/L and the order of toxicity of the compounds was (lowest to highest): Citalopram, fluvoxamine, paroxetine, fluoxetine, sertraline. Mortality data for the 8-d chronic tests were similar to the 48-h acute data. The SSRIs negatively affected C. dubia reproduction by reducing the number of neonates per female, and for some SSRIs, by reducing the number of broods per female. For sertraline, the most toxic SSRI, the LOEC for the number of neonates per female was 0.045 mg/L and the NOEC was 0.009 mg/L. Results indicate that SSRIs can impact survival and reproduction of C. dubia; however, only at concentrations that are considerably higher than those expected in the environment.

Environmental risk assessment of paroxetine

Paroxetine hydrochloride hemihydrate (the active ingredient in Paxil) is a pharmaceutical compound used for the treatment of depression, social anxiety disorder, obsessive compulsive disorder, panic disorder, and generalized anxiety disorder. Paroxetine (PA) is extensively metabolized in humans, with about 97% of the parent compound being excreted as metabolites through the urine and feces of patients. Therefore PA and metabolites have the potential to be discharged into wastewater treatment systems after therapeutic use. PA and its major human metabolite (PM) were investigated using studies designed to describe physical/chemical characteristics and determine their fate and effects in the aquatic environment. A significant portion of the PM entering a wastewater treatment plant would be expected to biodegrade given the higher activated sludge solids concentrations present in a typical wastewater treatment plant. The potential for direct photolysis of PM is also possible based on photolysis results for PA itself. These results provide strong support for expecting that PA and PM residuals will not persist in the aquatic environment after discharge from a wastewater treatment facility. This conclusion is also supported by the results of a USGS monitoring study, where no PM was detected in any of the samples at the 260 ng/L reporting limit. The results presented here also demonstrate the importance of understanding the human metabolism of a pharmaceutical so that the appropriate molecule(s) is used for fate and effects studies. In addition to the PA fate studies, PM was investigated using studies designed to determine potential environmental effects and a predicted no effect level (PNEC). The average measured activated sludge respiration inhibition value (EC50) for PM was 82 mg/L. The measured Microtox EC50 value was 33.0 mg/L, while the Daphnia magna EC50 value was 35.0 mg/L. The PNEC for PM was calculated to be 35.0 microg/L. Fate data were then used in a new watershed-based environmental risk assessment model, PhATE, to predict environmental concentrations (PECs). Comparison of the calculated PECs with the PNEC allows an assessment of potential environmental risk. Within the 1-99% of stream segments in the PhATE model, PEC values ranged from 0.003 to 100 ng/L. The risk assessment PEC/PNEC ratios ranged from approximately 3 x 10(-8) to approximately 3 x 10(-3), indicating a wide margin of safety, since a PEC/PNEC ratio <1 is generally considered to represent a low risk to the environment. In addition, Microtox studies carried out on PM biodegradation byproducts indicated no detectable residual toxicity. Any compounds in the environment as a result of the biodegradation of PM should be innocuous polar byproducts that should not exert any toxic effects.

Paroxetin-Entzugs-Syndrom als Differenzialdiagnose der akuten neonatalen Enzephalopathie?

Paroxetine, a selective serotonin reuptake inhibitor (SSRI) may be given in severe cases of maternal depression and panic disorders during pregnancy. However, it may lead to severe withdrawal symptoms: respiratory distress, jitteriness, convulsions, hypoglycaemia, an impaired muscle tone and necrotising enterocolitis. These symptoms, also called neonatal withdrawal syndrome, may last up to one month. We report a girl born at 37 weeks of gestation presenting 12 hours after birth with hypopnea, bradycardia and a decreased muscular tone of unknown origin. The child was transferred to the NICU and was intubated and ventilated mechanically. Within the first days the patient also developed cerebral seizures. The EEG showed severe abnormalities. Later we learned that the patient's mother had been treated with Paroxetine during pregnancy. The patient recovered after two days of ventilation and anticonvulsive medication with phenobarbital. The EEG result showed a siginificant improvement. At day 10 she was discharged in good condition. Recognition and treatment of the presented neonatal problems could have been more effective and faster, if the attending pediatricians had been informed earlier about the maternal medication with SSRIs. Neonates of mothers who were treated with SSRIs during pregnancy should be monitored. Paroxetine withdrawal syndrome should be considered as one of the differential diagnosis of neonatal encephalopathy.

The toxicity profile of a single dose of paroxetine: an alternative approach to acute toxicity testing in the rat

In this study we have examined the effect of a single administration of the selective serotonin reuptake inhibitor, paroxetine (120-300 mg kg(-1), orally) in a recently developed rodent model of acute toxicity testing. Reduced body-weight, food consumption, water consumption and body temperature were observed in all paroxetine-treated groups, which were reversible within 7 days. Five days after administration, a dose-dependent increase in red blood cells, haemoglobin and haematocrit was observed with the 3 higher dose levels of paroxetine, which was significant in the 240 and 300 mg kg(-1) treatment groups (P < 0.05). Hyperactivity was apparent in the first 24 hr following treatment, as was evidence of the serotonin syndrome. When the animals were sacrificed (11 days after drug administration), an increase in liver weight was observed in the highest dose. These results are in agreement with those previously observed with paroxetine at the preclinical and clinical levels. They demonstrate that this rodent model, because of its multi-parameter nature, is a useful method for examining the consequences of a single high dose of an antidepressant drug.