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 ß 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.

Orange peels modulate antioxidant markers and key enzymes relevant to erection in the penile tissue of paroxetine-treated rats.

In comparison to other antidepressant drugs, erectile dysfunction (ED) is more pronounced in paroxetine use. On the other hand, orange (Citrus sinensis) peels commonly consumed in various forms are used in folkloric medicine for ED management. Thus, this study evaluated the effect of orange peels infusion on sexual behaviour, nitric oxide (NO) level and some enzymes (arginase, phosphodiesterase-5 [PDE-5], acetylcholinesterase [AChE] and adenosine deaminase [ADA]) in paroxetine-treated rats. Erectile dysfunction was induced with paroxetine (10 mg/kg body weight). The animals were grouped into five (n = 6): normal rats; paroxetine-induced rats; paroxetine-induced rats treated with sildenafil citrate (5 mg/kg); paroxetine-induced rats treated with orange peels infusion (50 mg/kg); Paroxetine induced rats treated with orange peel infusions (100 mg/kg). The results revealed a significant decrease in sexual behaviour, NO level and the activities of antioxidant enzymes, while there was a significant increase in arginase, PDE-5, AChE and ADA activities in paroxetine-induced rats. However, orange peel infusions ameliorated erectile dysfunction in paroxetine-treated rats. This study showed some possible biochemical basis underlying the use of orange peels infusion in erectile dysfunction management.

Toxicity of Bupropion Overdose Compared With Selective Serotonin Reuptake Inhibitors.

OBJECTIVES: Adolescent depression and attempted and completed suicide are increasing in the United States. Because suicide is often impulsive, the means of self-harm are frequently items of convenience like medication. Authors of a recent study compared tricyclic antidepressant overdose to bupropion overdose. Fluoxetine and escitalopram are the only agents with Food and Drug Administration approval for pediatric depression, but off-label bupropion prescriptions are common. We sought to compare the effects of selective serotonin reuptake inhibitors (SSRIs) and bupropion in overdose. METHODS: This was an analysis of the National Poison Data System from June 2013 through December 2017 for adolescent (ages 10-19) exposures to SSRIs or bupropion coded as "suspected suicide." Demographics, clinical effects, therapies, and medical outcome were analyzed. RESULTS: There were 30 026 cases during the study period. Sertraline and fluoxetine accounted for nearly 60%, whereas bupropion was reported in 11.7%. Bupropion exposure was significantly associated with death (0.23% vs 0%; P < .001) or serious outcome (58.1% vs 19%; P < .001) as well as the 10 most common clinical effects, including seizures (27.0% vs 8.5%; P < .001) and hallucinations (28.6% vs 4.3%; P < .001). Bupropion exposure was significantly associated with the need for cardiopulmonary resuscitation (0.51% vs 0.01%; P < .001), intubation (4.9% vs 0.3%; P < .001), vasopressors (1.1% vs 0.2%; P < .001), and benzodiazepines (34.2% vs 5.5%; P < .001). There was a significant increase in all exposures and in proportion of serious outcomes over time. CONCLUSIONS: Adolescents who attempt self-harm are at higher risk for serious morbidity and poor outcomes with bupropion than with SSRIs. These risks, and the patient's propensity for self-harm, should be evaluated when therapy with bupropion is considered.

Assessment of trazodone-induced cardiotoxicity after repeated doses in rats.

Trazodone (TRZ) is an antidepressant drug commonly used in the treatment of depression, anxiety, and insomnia. Although some studies demonstrated the adverse effects of TRZ related to cardiovascular system, the conflicting results were observed in these studies. Therefore, we aimed to investigate the cardiac adverse effects of TRZ in rats at repeated doses in our study. In accordance with this purpose, TRZ was administered orally to rats at 5, 10, and 20 mg/kg doses for 28 days. Electrocardiogram records, serum aspartate aminotransferase (AST), lactate dehydrogenase, creatine kinase-myoglobin band, cardiac troponin-T (cTn-T) levels, DNA damage in cardiomyocytes, and histologic view of heart tissues were evaluated. In addition, glutathione (GSH) and malondialdehyde (MDA) levels were measured to determine the oxidative status of cardiac tissue after TRZ administration. Heart rate was decreased, PR interval was prolonged, and QRS and T amplitudes were decreased in 20 mg/kg TRZ-administered group compared to the control group. Serum AST and cTn-T levels were significantly increased in 10 and 20 mg/kg TRZ-administered rats with respect to control rats. DNA damage was significantly increased in these groups. Additionally, degenerative histopathologic findings were observed in TRZ-administered groups. Although there was no difference in MDA levels between groups, GSH levels were significantly decreased in 10 and 20 mg/kg TRZ-administered groups compared to the control group. Our results have shown that TRZ induced cardiotoxicity in rats dose-dependently. It is assumed that oxidative stress related to GSH depletion may be accompanied by these adverse effects.

Bilateral sciatic neuropathy with severe rhabdomyolysis following venlafaxine overdose: A case report.

RATIONALE: Venlafaxine is an antidepressant and anxiolytic agent that functions by inhibiting central serotonin and norepinephrine reuptake, and it is a relatively recently introduced drug. In particular, overdose of venlafaxine has been reported to cause severe cardiac toxicity including ventricular tachycardia, prolongation of QT interval, and seizure or severe muscular injury. However, reports describing venlafaxine-induced rhabdomyolysis with neuropathy remain scarce. Accordingly, we report such a case involving a 49-year-old woman with bilateral sciatic neuropathy combined with rhabdomyolysis following venlafaxine overdose. PATIENT CONCERNS: The patient complained of severe pain and tenderness in both thighs, weakness in both ankle flexor and extensor muscles, and a tingling sensation in the toes of both feet. DIAGNOSES: Bilateral sciatic neuropathy combined with rhabdomyolysis following venlafaxine overdose. INTERVENTION: Needle electromyography revealed fibrillation potentials and positive sharp waves, with absent recruitment in all the major muscles innervating the sciatic nerve bilaterally. Pelvic magnetic resonance imaging was performed after electromyography and revealed multifocal enhancement of signal intensity, suggesting muscle necrosis in the gluteus and thigh muscles, and swelling of both sciatic nerves on short tau inversion recovery (STIR) imaging sequences. OUTCOMES: Two months later, the patient's ankle dorsiflexion strength, measured with manual muscle test, was grade 0/0, and ankle plantar flexion was grade 0/0. The patient reported little sensation at the lateral and posterior aspects of her lower leg, and dorsum and sole of the foot. A follow-up electromyography study revealed improvement in the long head of the right biceps femoris; polyphasic motor unit action potentials with diminished recruitment were observed, but otherwise unchanged. LESSONS: When encountering patients who have overdosed on venlafaxine, it is very important to detect and treat severe complications such as cardiac toxicity, seizure, and rhabdomyolysis, among others. However, if rhabdomyolysis has already materialized, it should not be forgotten that the secondary damage caused by it. Physicians should rapidly detect and be minimized to mitigate future complications.

In vitro genotoxic and cytotoxic effects of doxepin and escitalopram on human peripheral lymphocytes.

Antidepressants are drugs used for the treatment of many psychiatric conditions including depression. There are findings suggesting that these drugs might have genotoxic, carcinogenic, and/or mutagenic effects. Therefore, the present in vitro study is intended to investigate potential genotoxic and cytotoxic effects of the antidepressants escitalopram (selective serotonin reuptake inhibitor) and doxepin (Tricyclic antidepressant) on human peripheral lymphocytes cytokinesis-block micronucleus (CBMN), sister chromatid exchange (SCE), and single cell gel electrophoresis (alkaline comet assay) were used for the purpose of the study. In the study, four different concentrations of both drugs (1, 2.5, 5, and 10 µg/mL) were administered to human peripheral lymphocytes for 24 h. The tested concentrations of both drugs were found to exhibit no cytotoxic and mitotic inhibitory effects. SCE increase caused by 5 and 10 µg/mL of escitalopram was found statistically significant, while no statistically significant increase was observed in DNA damage and micronucleus (MN) formation. Moreover, the increase caused by doxepin in MN formation was not found statistically significant. Besides, 10 µg/mL of doxepin was demonstrated to significantly increase arbitrary unit and SCE formation. These findings suggest that the investigated concentrations of escitalopram and doxepin were non-cytotoxic but potentially genotoxic at higher concentrations.

Effects of the antidepressant, mianserin, on early development of fish embryos at low environmentally relevant concentrations.

Pharmaceuticals have been considered as emerging organic contaminants in the environment that might pose huge risk to the non-target aquatic organisms. Mianserin, a tetracyclic antidepressant, is present at low detectable concentrations in the aquatic environment; however, limited attention has been devoted to its potential adverse effects on the aquatic animals. In the present study, we first performed an acute toxicity test for mianserin exposure using zebrafish (Danio rerio) embryos during 4-124h post fertilization (hpf). Time-dependent lethal concentrations of mianserin exposure on the zebrafish embryos were firstly determined at mg/L levels. Then, a series of sublethal concentrations of 0.01, 0.1, 1, 10, 100, and 1000µg/L of mianserin were prepared for the short-term exposure of zebrafish embryos for 120h. The results showed that mianserin exposure reduced the body length of zebrafish larvae, in addition to altering multiple physiological and biochemical parameters in the exposed embryos/larvae. A dose-dependent inhibition of the total antioxidant capacity and total cholinesterase activity was revealed in the exposed fish larvae upon increasing the concentrations of mianserin exposure. A U-shaped concentration-dependent response curve was observed for the adrenocorticotropic hormone; however, an inversed U-shaped response curve was obtained for the monoamine oxidase level in response to mianserin exposure. Activities of the total adenosine triphosphatase (T-ATPase), Na+/K+-ATPase, and Ca2+/Mg2+-ATPase were significantly increased in the fish larvae exposed to relatively high doses of mianserin; interestingly however, low dose of mianserin at 10ng/L inhibited their Na+/K+-ATPase and T-ATPase activities. Additionally, the coordinated regulation of cyclic adenosine monophosphate and protein kinase A was observed in the mianserin-exposed fish larvae, implying a reserved signaling pathway involved in the fish response to the antidepressant. Therefore, our study demonstrated that mianserin exposure significantly affected the early development of fish embryos at environmentally relevant concentrations, and suggested that the risk of pharmaceutical contamination of the aquatic environment, even at low doses, should receive more attention.

Atypical Findings in Massive Bupropion Overdose: A Case Report and Discussion of Psychopharmacologic Issues.

Bupropion is an atypical antidepressant that is structurally similar to amphetamines. Its primary toxic effects include seizure, sinus tachycardia, hypertension, and agitation; however, at higher amounts of ingestion, paradoxical cardiac effects are seen. We report the case of a 21-year-old woman who ingested 13.5 g of bupropion, a dose higher than any other previously reported. The patient presented with seizure, sinus tachycardia with prolonged QTc and QRS intervals, dilated pupils, and agitation. Four days after overdose, the patient's sinus tachycardia and prolonged QTc and QRS intervals resolved with symptomatic management, but she soon developed sinus bradycardia, hypotension, and mild transaminitis. With continued conservative management and close monitoring, her sinus bradycardia resolved 8 days after the overdose. The transaminitis resolved 12 days after the overdose. Our findings are consistent with previously reported toxic effects associated with common overdose amounts of bupropion. In addition, we have observed transient cardiotoxicity manifesting as sinus bradycardia associated with massive bupropion overdose. These findings are less frequently reported and must be considered when managing patients with massive bupropion overdose. We review the psychopharmacologic implications of this and comment on previous literature.

Endoplasmic Reticulum Stress Induction and ERK1/2 Activation Contribute to Nefazodone-Induced Toxicity in Hepatic Cells.

Nefazodone, an antagonist for the 5-hydroxytryptanine receptor, has been used for the treatment of depression. Acute liver injury has been documented to be associated with the use of nefazodone; however, the mechanisms of nefazodone-induced liver toxicity are not well defined. In this report, using biochemical and molecular analyses, we characterized the molecular mechanisms underlying the hepatotoxicity of nefazodone. We found that nefazodone induced endoplasmic reticulum (ER) stress in HepG2 cells, as the expression of typical ER stress markers, including CHOP, ATF-4, and p-eIF2α, was significantly increased, and splicing of XBP1 was observed. Nefazodone-suppressed protein secretion was evaluated using a Gaussia luciferase reporter assay that measures ER stress. The ER stress inhibitors (4-phenylbutyrate and salubrinal) and knockdown of ATF-4 gene attenuated nefazodone-induced ER stress and cytotoxicity. Nefazodone activated the MAPK signaling pathway, as indicated by increased phosphorylation of JNK, ERK1/2, and p38. Inhibition of ERK1/2 reduced ER stress caused by nefazodone. Taken together, our findings suggest that ER stress contributes to nefazodone-induced toxicity in HepG2 cells and that the MAPK signaling pathway plays an important role in ER stress.

Involvement of mitochondrial dysfunction in nefazodone-induced hepatotoxicity.

Nefazodone (NEF) is an antidepressive agent that was widely used in the treatment of depression until its withdrawal from the market, due to reports of liver injury and failure. NEF hepatotoxicity has been associated with mitochondrial impairment due to interference with the OXPHOS enzymatic activities, increased ROS generation and decreased antioxidant defenses. However, the mechanisms by which NEF induces mitochondrial dysfunction in hepatocytes are not completely understood. Here, we investigated the mitochondrial mechanisms affected upon NEF exposure and whether these might be linked to drug hepatotoxicity, in order to infer liabilities of future drug candidates. Two moderately hepatotoxic NEF concentrations (20 and 50 µM) were selected from dose-response growth curves performed in HepG2 cells. Cell viability, caspase activity, nuclear morphology, mitochondrial transmembrane potential, mitochondrial superoxide levels, and the expression of genes associated with different cellular pathways were evaluated at different time points. NEF treatment led to an increase in the expression of genes associated with DNA-damage response, antioxidant defense and apoptosis and a decreased expression of genes encoding proteins involved in oxidative phosphorylation, DNA repair, cell proliferation and cell cycle progression, which seem to constitute mechanisms underlying the observed mitochondrial and cell function impairment.

Does fish oil or folic acid prevent vascular changes in female progeny caused by maternal exposure to fluoxetine?

AIMS: Fluoxetine (FLX) is an antidepressant worldwide prescribed throughout life stages, including pregnancy and breastfeeding. Out of pregnancy, the combination of FLX with fish oil (FO) and folic acid (FA) is carried to enhance the therapeutic activity and reduce the side effects of the antidepressant. During pregnancy, FO and FA have been used to promote fetal development, and reduce, in mother, the risk of gestational and post-pregnancy depression. To evaluate if maternal exposure during pregnancy and lactation to FLX associated with FO or FA would prevent the antidepressant side effects in aorta reactivity and nitric oxide metabolites (NOx) plasmatic levels. We also sought to understand, in female offspring, the vascular effects of intrauterine and lactation exposure to FO and FA monotherapy. MAIN METHODS: Wistar rats were treated with water (control group), FLX (5mg/kg/day), FO (1.3g/kg/day), FA (3mg/kg/day), FLX+FO and FLX+FA, throughout pregnancy and lactation. On adulthood, in female offspring were evaluated the vascular reactivity to phenylephrine (Phe), the NOx and homocysteine (HCY) plasmatic levels. KEY FINDINGS: The developmental exposure to the associations of FO or FA with FLX did not correct the aortic hyporreactivity and increased NOx levels induced by intrauterine and lactation exposure to FLX. Also, isolated exposure to FO and FA did not interfere with Phe-induced aortic contraction and neither interferes with NOx and HCY plasmatic levels. SIGNIFICANCE: The developmental exposure to FO and FA was safe for vascular function of female offspring but did not prevent the vascular effects of FLX-exposure.

Bupropion Overdose Presenting as Status Epilepticus in an Infant.

BACKGROUND: Bupropion is a monocyclic antidepressant in the aminoketone class, structurally related to amphetamines. The Food and Drug Administration withdrew this product from the market in 1986 after seizures were reported in bulimic patients. It was later reintroduced in 1989 when the incidence of seizures was shown to be dose-related in the immediate release preparation. Massive bupropion ingestion has been associated with status epilepticus and cardiogenic shock in adults. Seizures have been reported in children, but not status epilepticus. This report highlights a patient who presented with status epilepticus and developed cardiopulmonary arrest after bupropion ingestion. False-positive amphetamine diagnosis from urine drug screen on presentation was reported. METHOD: We review the presentation, clinical course, diagnostic studies, and outcome of this patient. We then review the literature regarding bupropion overdose in children. RESULT: Symptoms of bupropion toxicity and risk for seizures are dose-dependent and fatalities have been reported. Our patient developed status epilepticus and cardiopulmonary arrest and then progressed to have a hypoxic ischemic encephalopathy and refractory symptomatic partial seizures. CONCLUSION: Our report highlights the need to keep this medication away from children in order to prevent accidental overdose.

Reactive oxygen species in the tumor niche triggers altered activation of macrophages and immunosuppression: Role of fluoxetine.

Macrophages are projected as one of the key players responsible for the progression of cancer. Classically activated (M1) macrophages are pro-inflammatory and have a central role in host defense, while alternatively activated (M2) macrophages are associated with immunosuppression. Macrophages residing at the site of neoplastic growth are alternately activated and are referred to as tumor-associated macrophages (TAMs). These "cooperate" with tumor tissue, promoting increased proliferation and immune escape. Selective serotonin reuptake inhibitors like fluoxetine have recently been reported to possess anti-inflammatory activity. We used fluoxetine to target tumor-associated inflammation and consequent alternate polarization of macrophages. We established that murine peritoneal macrophages progressed towards an altered activation state when exposed to cell-free tumor fluid, as evidenced by increased IL-6, IL-4 and IL-10 levels. These polarized macrophages showed significant pro-oxidant bias and increased p65 nuclear localization. It was further observed that these altered macrophages could induce oxidative insult and apoptosis in cultured mouse CD3(+) T cells. To validate these findings, we replicated key experiments in vivo, and observed that there was increased serum IL-6, IL-4 and IL-10 in tumor-bearing animals, with increased % CD206(+) cells within the tumor niche. TAMs showed increased nuclear localization of p65 with decreased Nrf2 expression in the nucleus. These results were associated with increase in apoptosis of CD3(+) T cells co-cultured with TAM-spent media. We could establish that fluoxetine treatment could specifically re-educate the macrophages both in vitro and in vivo by skewing their phenotype such that immune suppression mediated by tumor-dictated macrophages was successfully mitigated.

Assessment of in-utero venlafaxine induced, ROS-mediated, apoptotic neurodegeneration in fetal neocortex and neurobehavioral sequelae in rat offspring.

Venlafaxine (VEN), a serotonin and noradrenaline reuptake inhibitor is being used as a drug of choice for treating clinical depression even during pregnancy. It is an important therapeutic option in the treatment of perinatal depression, but the effects of VEN on fetus and the newborn are uncertain. Therefore, present study was undertaken to investigate the safety of in-utero exposure to VEN in terms of developmental neurotoxicity and neurodegenerative potential by using prenatal rat model. The selected doses of VEN (25, 40 and 50mg/kg) were administered to pregnant rats from GD 5 to 19 through oral gavage. The fetal brains were dissected and processed for histopathological measurements of neocortical thickness that showed significant reduction. Considering vulnerability of immature brain to free radical injury, VEN exposed neocortices were tested for reactive oxygen species (ROS) levels which were significantly increased. As ROS play important role in the initiation of apoptotic mechanisms, we explored for in situ detection of apoptosis by confocal microscopy that showed enhanced apoptosis including chromatin condensation which was further reconfirmed by electron microscopy. Substantially increased levels of pro-apoptotic protein Bax and decreased levels of anti-apoptotic protein Bcl2 as shown by western blotting also supported the increased neuro-apoptotic degeneration. For further correlation of these findings, prenatally VEN exposed young-adult rat offspring were assessed for open field exploratory behavior that showed increased anxiety-like and stereotypic responses indicating disturbed neurobehavioral pattern. The study concludes that prenatal VEN exposure may primarily enhance ROS generation that plays a key role in regulating release of proapoptotic factors from mitochondria and thereby enhancing apoptotic neurodegeneration that affect proliferation, migration and differentiation of cells, resulting in neuronal deficits manifested as long term neurobehavioral impairments.

Fluoxetine may worsen hyperoxia-induced lung damage in neonatal rats.

Fluoxetine shows controversial lung effects as it prevents pulmonary hypertension in adult rats but exposure during gestation causes pulmonary hypertension in neonatal rats. In the present study, we tested the null hypothesis that the antidepressant drug fluoxetine does not modify the development of bronchopulmonary dysplasia (BPD) in neonatal rats. Experimental categories included I: room air (controls) with daily injection of saline; II: room air with daily injection of 10 mg/kg fluoxetine, i.p., during two weeks; III: 60% oxygen with daily injection of saline; and IV: 60% oxygen with daily injection of 10 mg/kg fluoxetine, i.p., during two weeks. Hyperoxia resulted in significant reduction in alveolar density and an increase in pulmonary endocrine cells, as well as increases in muscle layer areas of bronchi and arteries. Fluoxetine treatment generated a further increase in muscularisation and did not significantly modify the hyperoxia-induced reductions in alveolar density and increases in the endocrine cells. In hyperoxia, Real-Time PCR showed a lower pulmonary expression of vascular endothelial growth factor (VEGF) with no significant changes in the expression of matrix metalloproteinases (MMP) 2 and 12. Fluoxetine did not affect VEGF or MMP-2 expression but it significantly increased MMP-12 mRNA in both normoxic and hyperoxic groups. Zymographic analysis of MMP-2 activity in bronchoalveolar fluid showed a significantly reduced MMP-2 activity in hyperoxia, while fluoxetine treatment restored MMP-2 activity to levels comparable with the normoxic group. In conclusion, our data show that fluoxetine may worsen bronchial and arterial muscularisation during development of BPD and may up-regulate MMP expression or activity.

Early-life citalopram-induced impairments in sexual behavior and the role of androgen receptor.

Postnatal treatment with selective serotonin reuptake inhibitors (SSRIs) has been found to affect brain development and the regulation of reproduction in rodent models. The normal masculinization process in the brain requires a transient decrease in serotonin (5-HT) levels in the brain during the second postnatal week. Strict regulation of androgen receptor (AR) and gonadotropin-releasing hormone (GnRH) expression is important to control male reproductive activity. Therefore, this study was designed to examine the effects of a potent SSRI (citalopram) on male sexual behavior and expression levels of AR and GnRH in adult male mice receiving either vehicle or citalopram (10mg/kg) daily during postnatal days 8-21. The citalopram-treated male mice showed altered sexual behavior, specifically a significant reduction in the number of intromissions preceding ejaculation compared with the vehicle-treated mice. The citalopram-treated male mice displayed elevated anxiety-like behavior in an open field test and lower locomotor activity in their home cage during the subjective night. Although there was no change in GnRH and AR mRNA levels in the preoptic area (POA), quantified by real-time polymerase chain reaction, immunostained AR cell numbers in the medial POA were decreased in the citalopram-treated male mice. These results suggest that the early-life inhibition of 5-HT transporters alters the regulation of AR expression in the medial POA, likely causing decreased sexual behavior and altered home cage activity in the subjective night.

In vivo and in vitro estrogenic activity of the antidepressant fluoxetine.

Recent years have seen an increase in the use of antidepressant drugs, especially fluoxetine (FLX), in sensitive populations, such as pregnant and lactating women. Although some evidence suggests a possible endocrine action of FLX, no specific studies have been performed to investigate this hypothesis. In the present study, we investigated the possible (anti)androgenic and (anti)estrogenic actions of FLX using Hershberger, uterotrophic (0.4, 1.7, and 17mg/kg), and reporter gene (7.6-129µM) assays. In the Hershberger assay, no differences were observed in androgen-dependent organ weights. However, the uterotrophic and gene reporter assays indicated a possible estrogenic action of FLX. Uterine weight increased in the 1.7 and 17mg/kg/day groups in the 3-day uterotrophic assay in immature rats. Additionally, noncytotoxic concentrations of FLX induced estrogenic responses and increased the estrogenic response of estradiol in MCF-7 breast cancer cells transfected with luciferase.