Detection of fluoxetine in brain, blood, liver and hair of rats using gas chromatography-mass spectrometry

Apoptotic effect of fluoxetine through the endoplasmic reticulum stress pathway in the human gastric cancer cell line AGS

Gastric cancer is the fourth most common cancer in the world. Fluoxetine (FLX), a selective serotonin reuptake inhibitor, can inhibit the growth of cancer cells by inducing apoptotic cell death through various signaling pathways. This study was aimed to determine the mechanism of apoptotic cell death induced by FLX in AGS cells. MTT assay for cell viability test and colony forming assay was performed for detection of cell proliferation. Western blot analysis was conducted for protein expression. Increased fluorescence intensity and chromatin condensation were observed using DAPI staining. Production of reactive oxygen species (ROS) was measured by DCFDA assay. AGS cell proliferation was remarkedly inhibited by FLX in a dose-dependent manner starting at a concentration of 20 μM. The expression of death receptors was increased, which resulted in elevated expression of activated caspases and cleaved PARP, leading to FLX-induced apoptosis. Moreover, FLX significantly increased production of ROS, and N-acetyl cysteine, which scavenges ROS, attenuated the cytotoxic effects of FLX. In addition, treatment with FLX increased the expression of the endoplasmic reticulum (ER) stress marker, CHOP. P53 protein expression in AGS cells also decreased significantly with FLX treatment. Inhibition of ER stress significantly decreased the expressions of death receptor 5 (DR5), cleaved caspase 3, and cleaved PARP, but not to control levels. FLX-induced apoptosis in AGS involved upregulation of death receptors, ROS generation, and activation of ER stress.

Detecting fluoxetine and norfluoxetine in wild bird tissues and feathers

The contamination of the environment with human pharmaceuticals is widespread and demand for such products is mounting globally. Wild vertebrates may be at particular risk from any effects from pharmaceuticals, because of the evolutionary conservation of drug targets. However, exposure of wildlife to pharmaceuticals is poorly characterised, partly due to challenges associated with detecting rapidly metabolised compounds. As part of a wider study on the behavioural effects of fluoxetine (Prozac) on Eurasian starlings (Sturnus vulgaris), we investigated which avian samples are best suited for detecting exposure to fluoxetine in free-living birds. We analysed plasma, various tissues and tail feathers (grown both in the wild and in captivity during the dosing period) from fluoxetine-treated birds (dosed daily with 0.035 mg kg^-1 bodyweight for 28 weeks), and liver tissue and tail feathers from sham-dosed birds. We detected fluoxetine in only two of twelve plasma samples from dosed birds. In dosed birds, median concentrations of free fluoxetine/norfluoxetine in tissues (two hour post-final dose) were: 111.2/67.6 ng g^-1 in liver, 29.6/5.7 ng g^-1 in kidney, 14.2/4.0 ng g^-1 in lung, 15.1/1.6 ng g^-1 in brain. We estimated that fluoxetine would remain detectable in liver and kidney approximately 4.5 times longer (90 h) than in brain (20h). In dosed birds, fluoxetine was detected in feathers regrown during the dosing period (median concentration = 11.4 ng g^-1) at concentrations significantly higher than in regrown feathers from control birds. Fluoxetine residues were detected in wild-grown feathers (grown before the birds were brought into captivity) at concentrations up to 27.0 ng g^-1, providing some evidence of likely exposure in the wild. Our results show liver and kidney can be used for detecting fluoxetine in avian carcasses and provide a first indication that feathers may be useful for assessing exposure to fluoxetine, and possibly other pharmaceuticals.

Metal-Binding Pharmacophore Library Yields the Discovery of a Glyoxalase 1 Inhibitor

Anxiety and depression are common, highly comorbid psychiatric diseases that account for a large proportion of worldwide medical disability. Glyoxalase 1 (GLO1) has been identified as a possible target for the treatment of anxiety and depression. GLO1 is a Zn²⁺-dependent enzyme that isomerizes a hemithioacetal, formed from glutathione and methylglyoxal, to a lactic acid thioester. To develop active inhibitors of GLO1, fragment-based drug discovery was used to identify fragments that could serve as core scaffolds for lead development. After screening a focused library of metal-binding pharmacophores, 8-(methylsulfonylamino)quinoline (8-MSQ) was identified as a hit. Through computational modeling and synthetic elaboration, a potent GLO1 inhibitor was developed with a novel sulfonamide core pharmacophore. A lead compound was demonstrated to penetrate the blood-brain barrier, elevate levels of methylglyoxal in the brain, and reduce depression-like behavior in mice. These findings provide the basis for GLO1 inhibitors to treat depression and related psychiatric illnesses.

Toxicokinetics, disposition and metabolism of fluoxetine in crabs

The disposition and metabolism of fluoxetine in the European shore crab and the Dungeness crab were assessed. Crabs received intracardiac doses of either 0.13 μg/kg or 0.5 mg/kg fluoxetine, respectively. In addition, fluoxetine was administered to Metacarcinus cancer by oral gavage at 7.8 mg/kg. The distribution of fluoxetine was quantified in haemolymph and digestive gland for both crabs, as well as brain, muscle, and testis of Carcinus maenas, over 12 days. The metabolite norfluoxetine, was also measured in C. maenas. Fluoxetine was mainly found in lipid rich tissues. Distribution coefficients increased for digestive gland until three days after fluoxetine administration and then decreased until the end of the observations. The highest distribution coefficients were obtained for brain. Norfluoxetine displayed continuously high levels in digestive gland and brain. The strong decrease in fluoxetine and the concomitant increase in norfluoxetine demonstrates that decapod crustaceans metabolise fluoxetine into the more biologically active norfluoxetine. Fluoxetine levels in the haemolymph of M. cancer declined within 20 h, but showed a second peak 25 h later, suggesting remobilisation from tissues sequestering the compound. The steady state volume distribution and the total body clearance of fluoxetine were high, consistent with high diffusion of fluoxetine into the peripheral tissues and biotransformation as an important elimination pathway. Oral administration of fluoxetine prolonged its half-life in M. cancer, but bioavailability was low. These results confirm the high distribution into nervous tissue, extensive biotransformation into the highly active norfluoxetine and a half-life similar to that observed in vertebrates.

Predictive framework for estimating exposure of birds to pharmaceuticals

We present and evaluate a framework for estimating concentrations of pharmaceuticals over time in wildlife feeding at wastewater treatment plants (WWTPs). The framework is composed of a series of predictive steps involving the estimation of pharmaceutical concentration in wastewater, accumulation into wildlife food items, and uptake by wildlife with subsequent distribution into, and elimination from, tissues. Because many pharmacokinetic parameters for wildlife are unavailable for the majority of drugs in use, a read-across approach was employed using either rodent or human data on absorption, distribution, metabolism, and excretion. Comparison of the different steps in the framework against experimental data for the scenario where birds are feeding on a WWTP contaminated with fluoxetine showed that estimated concentrations in wastewater treatment works were lower than measured concentrations; concentrations in food could be reasonably estimated if experimental bioaccumulation data are available; and read-across from rodent data worked better than human to bird read-across. The framework provides adequate predictions of plasma concentrations and of elimination behavior in birds but yields poor predictions of distribution in tissues. The approach holds promise, but it is important that we improve our understanding of the physiological similarities and differences between wild birds and domesticated laboratory mammals used in pharmaceutical efficacy/safety trials, so that the wealth of data available can be applied more effectively in ecological risk assessments. Environ Toxicol Chem 2017;36:2335-2344. © 2017 SETAC.

Oncostatic effects of fluoxetine in experimental colon cancer models

Colon cancer is one of the most common tumors in the human population. Recent studies have shown a reduced risk for colon cancer in patients given the antidepressant fluoxetine (FLX). The exact mechanism by which FLX might protect from colon cancer remains however controversial. Here, FLX reduced the development of different colon tumor xenografts, as well as proliferation in hypoxic tumor areas within them. FLX treatment also decreased microvessel numbers in tumors. Although FLX did not increase serum and tumor glucose levels as much as the colon chemotherapy gold standard Fluorouracil did, lactate levels were significantly augmented within tumors by FLX treatment. The gene expression of the MCT4 lactate transporter was significantly downregulated. Total protein amounts from the third and fifth mitochondrial complexes were significantly decreased by FLX in tumors. Cell culture experiments revealed that FLX reduced the mitochondrial membrane potential significantly and disabled the reactive oxygen species production of the third mitochondrial complex. Furthermore, FLX arrested hypoxic colon tumor cells in the G0/G1 phase of the cell-cycle. The expression of key cell-cycle-related checkpoint proteins was enhanced in cell culture and in vivo experiments. Therefore, we suggest FLX impairs energy generation, cell cycle progression and proliferation in tumor cells, especially under condition of hypoxia. This then leads to reduced microvessel formation and tumor shrinkage in xenograft models.

Fluoxetine induces preventive and complex effects against colon cancer development in epithelial and stromal areas in rats

Fluoxetine (FLX) is a drug commonly used as antidepressant. However, its effects on tumorigenesis remain controversial. Aiming to evaluate the effects of FLX treatment on early malignant changes, we analyzed serotonin (5-HT) metabolism and recognition, aberrant crypt foci (ACF), proliferative process, microvessels, vascular endothelial growth factor (VEGF), and cyclooxygenase-2 (COX-2) expression in colon tissue. Male Wistar rats received a daily FLX-gavage (30mgkg(-1)) and, a single dose of 1,2 dimethylhydrazine (DMH; i.p., 125mgkg(-1)). After 6 weeks of FLX-treatment, our results revealed that FLX and nor-fluoxetine (N-FLX) are present in colon tissue, which was related to significant increase in serotonin (5-HT) levels (P<0.05) possibly through a blockade in SERT mRNA (serotonin reuptake transporter; P<0.05) resulting in lower 5-hydroxyindoleacetic acid (5-HIAA) levels (P<0.01) and, 5-HT2C receptor mRNA expressions. FLX-treatment decreased dysplastic ACF development (P<0.01) and proliferative process (P<0.001) in epithelia. We observed a significant decrease in the development of malignant microvessels (P<0.05), VEGF (P<0.001), and COX-2 expression (P<0.01). These findings suggest that FLX may have oncostatic effects on carcinogenic colon tissue, probably due to its modulatory activity on 5-HT metabolism and/or its ability to reduce colonic malignant events.

Study on the neuroprotective effect of fluoxetine against MDMA-induced neurotoxicity on the serotonin transporter in rat brain using micro-PET

3, 4-Methylenedioxymethamphetamine (MDMA, "ecstasy") has toxic effects on serotonergic neurons in the brain. Our aim was to determine whether N,N-dimethyl-2-(2-amino-4-[(18)F]-fluorophenylthio) benzylamine (4-[(18)F]-ADAM; a serotonin transporter imaging agent) and micropositron emission tomography (micro-PET) can be used to examine in vivo the effect of fluoxetine on MDMA-induced loss of serotonin transporters in rat brain. Male Sprague-Dawley rats were injected with fluoxetine [1 dose, 5 mg/kg, subcutaneously (s.c.)] followed by MDMA (twice a day for 4 consecutive days, 10 mg/kg, s.c.). Micro-PET with 4-[(18)F]-ADAM was performed on days 4, 10, 17, 24, and 31. In addition, the time course of occupancy by fluoxetine at 4-[(18)F]-ADAM sites was measured. Specific 4-[(18)F]-ADAM uptake ratios (SURs) were calculated from the micro-PET imaging data for various brain regions. Immunohistochemistry was performed 7 days after the last micro-PET scan. From day 4 to day 31, SURs were markedly decreased (by approximately 55-75% compared to control values) in all brain regions in MDMA-treated rats. The effect of MDMA was markedly attenuated (approximately 30-50%) by fluoxetine. The fluoxetine-induced decrease in uptake in different brain regions was 40-75% at 90-min postinjection, and this decrease returned to baseline values in most brain regions by day 31. The distribution and intensity of serotonin transporter (SERT) immunostaining in the brain paralleled the PET imaging results, suggesting that a single dose of fluoxetine provides long-lasting protection against MDMA-induced loss of SERT and that such neuroprotection is detectable in vivo by 4-[(18)F]-ADAM micro-PET.

The effects of pH on fluoxetine in Japanese medaka (Oryzias latipes): acute toxicity in fish larvae and bioaccumulation in juvenile fish

Recent detection of fluoxetine in the aquatic environment and fish suggests a possibly high accumulation of fluoxetine; however, no report is available on the bioaccumulation of fluoxetine in aquatic organisms. Since bioaccumulation of fluoxetine was probably dependent on pH near the pK(a) value of 10.1, experiments were conducted approximately at pH 7, 8, and 9. Distribution coefficients between 1-octanol and water (D(ow)), and those between synthetic membrane vesicles (liposomes) and water (D(lip-wat)) were determined at pH 7, 8, and 9. The D(ow) and D(lip-wat) values increased significantly with increasing pH. Acute toxicity tests were performed using Japanese medaka (Oryzias latipes) prior to the bioaccumulation test, and 96-h LC(50) values were 5.5, 1.3, and 0.20mgl(-1) at pH 7, 8, and 9, respectively. In the bioaccumulation test, concentrations of fluoxetine and its major metabolite, norfluoxetine, in the fish body and liver were measured. The bioconcentration factors (BCF) of fluoxetine for Japanese medaka were 8.8, 3.0x10, and 2.6x10(2) in the body and 3.3x10(2), 5.8x10(2), and 3.1x10(3) in the liver at pH 7, 8, and 9, respectively. The BCF values were lower at pH 7 and higher at pH 9 mainly because of the increase in nonionized species with significantly higher hydrophobicity than the ionized species at pH values closer to pK(a). A similar trend was obtained for the concentration of norfluoxetine in the fish but the pseudo-BCF values (the ratio of the norfluoxetine concentration in the fish and the fluoxetine concentration in test water) were higher than the BCF value of fluoxetine at all pH conditions.

On-line sample stacking and short-end injection CE for the determination of fluoxetine and norfluoxetine in plasma: Method development and validation using experimental designs

A short-end injection CE method combining field-amplified sample stacking (FASS) is presented for the analysis of fluoxetine (FL) and norfluoxetine in plasma. In this study, FASS enhanced the sensitivity about 1100-fold, while short-end injection reduced the analysis time to less than 4 min. Parameters involved in the separations were investigated using a central composite design (CCD) and response surface methodology to optimize the separation conditions in a total of only 32 runs. Samples injected into the capillary for 99.9 s at a voltage of -5 kV were stacked in a water plug (0.5 psi, 9 s). Baseline resolution of FL and its major metabolite was achieved using a BGE formulation consisting of phosphate-triethanolamine at low pH, and a separation voltage of -10 kV. Five percent methanol was added as organic modifier to enhance selectivity and resolution. The linear range was between 10 and 500 ng/mL (r >0.9946), covering the expected plasma therapeutic ranges. The LOD in plasma were 4 ng/mL (S/N = 3), a value comparable to that obtained using LC-MS, showing the success of the on-line stacking technique. Our method was also successfully validated in quantification and pharmacokinetic studies with three volunteer plasma samples and could be applied to pharmacogenetic studies.

Chronic fluoxetine treatment attenuates stressor-induced changes in temperature, heart rate, and neuronal activation in the olfactory bulbectomized rat

The olfactory bulbectomized (OB) rat is a well-characterized animal model that exhibits a number of behavioral and neurochemical changes that have relevance to clinical depression. Hyperactivity in the open field is the most widely used parameter assessed in this model and is reversed following chronic, but not acute, antidepressant treatment. This study investigated OB-induced alterations in heart rate, body temperature, and neuronal activation following open-field exposure and the impact of chronic treatment with fluoxetine on these parameters. Upon placement in the open field, OB rats exhibited a characteristic hyperactivity response. Heart rate and body temperature were increased in sham-operated rats following open-field exposure, a predictable response to stress, which was significantly reduced in OB rats. Moreover bulbectomy reduced open field-induced cFOS expression in the basal nucleus of the stria terminalis while concurrently increasing expression in the hippocampus, amygdala, paraventricular nucleus of the thalamus, and dorsal raphe nucleus. Chronic fluoxetine treatment (10 mg/kg subcutaneous once daily for 5 weeks) attenuated all of these OB-associated changes. In conclusion, OB rats exhibit alterations in behavior, body temperature, heart rate, and neuronal activation in response to open-field exposure, which are reversed following chronic fluoxetine administration. These results identify stress-sensitive regions within the brain which are altered following bulbectomy and which may underlie the abnormal behavioral and physiological changes observed in this rodent model of depression.

A recursive-partitioning model for blood–brain barrier permeation

A series of bagged recursive partitioning models for log(BB) is presented. Using a LGO-CV, three sets of physical property descriptors are evaluated and found to have Q2 values of 0.51 (CPSA), 0.53 (Ro5x) and 0.53 (MOE). Extrapolating these models to Pfizer chemical space is difficult due to P-glycoprotein (P-gp) mediated efflux. Low correlation coefficients for this test set are improved (R2 = 0.39) when compounds known to be P-gp substrates or statistical extrapolations are removed. The use of simple linear models for specific chemical series is also found to improve the correlation over a limited chemical space.

The mechanisms involved in the long-lasting neuroprotective effect of fluoxetine against MDMA ('ecstasy')-induced degeneration of 5-HT nerve endings in rat brain

1. It has been reported that co-administration of fluoxetine with 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') prevents MDMA-induced degeneration of 5-HT nerve endings in rat brain. The mechanisms involved have now been investigated. 2. MDMA (15 mg kg(-1), i.p.) administration produced a neurotoxic loss of 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) in cortex, hippocampus and striatum and a reduction in cortical [3H]-paroxetine binding 7 days later. 3. Fluoxetine (10 mg kg(-1), i.p., x2, 60 min apart) administered concurrently with MDMA or given 2 and 4 days earlier provided complete protection, and significant protection when given 7 days earlier. Fluvoxamine (15 mg kg(-1), i.p., x2, 60 min apart) only produced neuroprotection when administered concurrently. Fluoxetine (10 mg kg(-1), x2) markedly increased the K(D) and reduced the B(max) of cortical [3H]-paroxetine binding 2 and 4 days later. The B(max) was still decreased 7 days later, but the K(D) was unchanged. [3H]-Paroxetine binding characteristics were unchanged 24 h after fluvoxamine (15 mg kg(-1), x2). 4. A significant cerebral concentration of fluoxetine plus norfluoxetine was detected over the 7 days following fluoxetine administration. The fluvoxamine concentration had decreased markedly by 24 h. 5. Pretreatment with fluoxetine (10 mg kg(-1), x2) failed to alter cerebral MDMA accumulation compared to saline pretreated controls. 6. Neither fluoxetine or fluvoxamine altered MDMA-induced acute hyperthermia. 7. These data demonstrate that fluoxetine produces long-lasting protection against MDMA-induced neurodegeneration, an effect apparently related to the presence of the drug and its active metabolite inhibiting the 5-HT transporter. Fluoxetine does not alter the metabolism of MDMA or its rate of cerebral accumulation.

Hyphenated chromatographic methods for biomaterials

The improvement in hyphenated analytical techniques has significantly widened their applications to the analysis of biomaterials. In this article, we discuss recent advances in applications of hyphenated chromatographic techniques including capillary electrophoresis to the analyses of biological samples. As tools of separation, gas chromatography, high-performance liquid chromatography and capillary electrophoresis are considered with special emphasis on applications utilizing the hyphenation of these methods to mass spectrometry. Moreover, applications using other detection methods such as Fourier transform infrared spectroscopy hyphenated to gas chromatography and photodiode array detector combined with high-performance liquid chromatography or capillary electrophoresis are also discussed. Owing to their high sensitivity, luminescence-based detection systems such as laser-induced fluorescence and chemiluminescence are also included in this review.

Determination of four selective serotonin reuptake inhibitors by capillary isotachophoresis

We determined an optimal electrolyte system for isotachophoresis (ITP) with conductivity detection of citalopram, fluoxetine, fluvoxamine and sertraline. The analysis conditions were applied to the determination of these selective serotonin re-uptake inhibitors in antidepressant drugs. It is shown that capillary ITP with conductivity detection is a simple and quick method for the determination of citalopram, fluoxetine, fluvoxamine and sertraline in drugs.