Co-administration Of Fluoxetine Research Articles

NSC689857, an inhibitor of Skp2, produces antidepressant-like effects in mice.

We have previously reported that two inhibitors of an E3 ligase S-phase kinase-associated protein 2 (Skp2), SMIP004 and C1, have an antidepressant-like effect in non-stressed and chronically stressed mice. This prompted us to ask whether other Skp2 inhibitors could also have an antidepressant effect. Here, we used NSC689857, another Skp2 inhibitor, to investigate this hypothesis. The results showed that administration of NSC689857 (5 mg/kg) produced an antidepressant-like effect in a time-dependent manner in non-stressed male mice, which started 8 days after drug administration. Dose-dependent analysis showed that administration of 5 and 10 mg/kg, but not 1 mg/kg, of NSC689857 produced antidepressant-like effects in both non-stressed male and female mice. Administration of NSC689857 (5 mg/kg) also induced antidepressant-like effects in non-stressed male mice when administered three times within 24 h (24, 5, and 1 h before testing) but not when administered acutely (1 h before testing). In addition, NSC689857 and fluoxetine coadministration produced additive antidepressant-like effects in non-stressed male mice. These effects of NSC689857 were not associated with the changes in locomotor activity. Administration of NSC689857 (5 mg/kg) also attenuated depression-like behaviors in male mice induced by chronic social defeat stress, suggesting therapeutic potential of NSC689857 in depression. Overall, these results suggest that NSC689857 is capable of exerting antidepressant-like effects in both non-stressed and chronically stressed mice.

Role of Allicin in Combination with Fluoxetine for the Treatment of Major Depressive Disorder in Rodents: Pharmacokinetic and Pharmacodynamic Study

Background: Depression is one of the most common neurological disorders for which only symptomatic treatment is available with synthetic drugs with serious side effects. Allicin [S-(2-propenyl)-2-propene-1-sulfinothioate] is a bioactive component derived from Allium sativum L. (Garlic). It has the property to penetrate the blood-brain barrier, which reveals its neuroprotective property. A synthetic drug named fluoxetine (selective serotonin re-uptake inhibitor) was introduced for the clinical treatment of depression. It is a selective serotonin re-uptake inhibitor that is well absorbed after oral administration. Aims and Objectives: This study aimed to evaluate the anti-depressant effect of fluoxetine alone and in combination with allicin. Methods: A pharmacokinetic study of allicin alone as well as in combination with fluoxetine was conducted to evaluate peak concentration, peak concentration time, and area under the curve in blood plasma. Furthermore, the biochemical analysis of neurotrophin levels of brain-derived neurotrophic factor (BDNF), serotonin, and dopamine was also performed to determine the anti-depressant activity with synergism effect of allicin and fluoxetine. Results: The results of a pharmacokinetic study for co-administration of fluoxetine with allicin and enhanced neurotrophins and monoamines levels confirmed their effectiveness against depression. They may also be effective in suicidal risk associated with anti-depressant drugs. Conclusion: A combination of synthetic drugs with herbal compounds may be an alternate and effective therapy to overcome harmful effects.

Identification of the antidepressive properties of C1, a specific inhibitor of Skp2, in mice.

We have reported that SMIP004, an inhibitor of S-phase kinase-associated protein 2 (Skp2), displays antidepressant-like activities in stress-naïve and chronically stressed mice. Here, we investigated the antidepressant-like effect of C1, another inhibitor of Skp2, in mouse models following acute or chronic drug administration at different doses and treatment times by using the tail suspension test (TST), forced swimming test (FST), and social interaction test (SIT). The time- and dose-dependent results showed that the antidepressant-like effect of C1 occurred 8 days after the drug treatment, and C1 produced antidepressant-like activities at the dose of 5 and 10 but not 1 mg/kg in male or female mice. C1 administration (5 mg/kg) also induced antidepressant-like effects in stress-naïve mice in a three-times administration mode within 24 h (24, 5, and 1 h before the test) but not in an acute administration mode (1 h before the test). The C1 and fluoxetine co-administration produced additive effect on depression-like behaviors in stress-naïve mice. The antidepressant-like effect of C1 was not associated with the change in locomotor activity, as no increased locomotor activity was observed in different treatment modes. Furthermore, the long-term C1 treatment (5 mg/kg) was found to ameliorate the depression-like behaviors in chronic social defeat stress-exposed mice, suggesting that C1 can produce antidepressant-like actions in stress conditions. Since C1 is a specific inhibitor of Skp2, our results demonstrate that inhibition of Skp2 might be a potential strategy for the treatment of depression, and Skp2 may be potential target for the development of novel antidepressants.

Dopamine receptor agonist rotigotine-loaded microspheres ameliorates sexual function deteriorated by fluoxetine in depression rats.

Low dopamine levels may cause depressive symptoms. Dopamine is also involved in sexual behavior. Rotigotine is a nonergolinic dopamine agonist. Fluoxetine, an antidepressant that acts as a selective serotonin (5-HT) reuptake inhibitor, may cause moderate or severe sexual dysfunction. This study aims to investigate the effects of rotigotine-loaded microspheres (RoMS) and rotigotine on fluoxetine-induced impairment of sexual function and their efficacy in depression-model rats. Rats with depressive-like behavior, induced by bilateral olfactory bulbectomy, were treated intragastrically with fluoxetine and co-administered RoMS or rotigotine subcutaneously. Then, copulatory behavior and open field tests were conducted. Serum luteinizing hormone and testosterone levels were assayed with enzyme-linked immunosorbent assay kits. The concentrations of 5-HT, dopamine, and norepinephrine were measured in the raphe nucleus and amygdala. The results showed that sexual function was decreased in olfactory bulbectomy rats and significantly deteriorated by fluoxetine. Co-administration of RoMS partly reversed the fluoxetine-induced impairment of sexual function, but rotigotine administration did not produce any improvement. Hyperactivity in olfactory bulbectomy rats was significantly attenuated by fluoxetine but was not influenced by co-administration of RoMS. Compared with the fluoxetine group, RoMS increased the testosterone, luteinizing hormone, dopamine, and norepinephrine levels. These findings indicated that RoMS improved the fluoxetine-induced impairment of sexual function and did not affect its antidepressant efficacy in depressive rats, which provides a potential treatment for patients with depression that can reduce the possibility of sexual dysfunction. Additionally, co-administration of fluoxetine with RoMS may be beneficial for Parkinson's disease patients with depression.

Different Effects of Fluoxetine and Paroxetine Combined with Vitamin D3 in Ovariectomized Rats Exposed to Unpredictable Stress

Background: Vitamin D3 (VD3) is involved in the pathophysiological mechanisms of affective-related disorders and controls the functional activity of various hormonal systems. The complex interaction between estrogen and VD3 creates a neurobiological basis for their participation in similar behavioral disorders. Objectives: This study aimed to evaluate whether VD3 (5.0 mg/kg, s.c.) facilitates the antidepressant-like action of fluoxetine (10.0 mg/kg, i.p.) or paroxetine (10.0 mg/kg, i.p.) by enhancing the antidepressant-like activity of these drugs in adult long-term Ovariectomized (OVX) rats subjected to Chronic Unpredictable Mild Stress (CUMS) protocol for 6 weeks. Methods: Sucrose Preference (SPT) and Forced Swim (FST) tests were performed to evaluate the anhedonia state and depressive symptoms, respectively. The Open-Field Test (OFT) was carried out to measure locomotor activity as well as grooming behavior produced by CUMS in long-term OVX rats. Corticosterone (CS)/estradiol (E2) in the serum was tested by rat ELISA kits. NF-kB, 5-HT/5-HIIA, and pro-inflammatory cytokine levels in the hippocampus were also examined by rat ELISA kits. Results: The results of this study suggest that combined treatment with fluoxetine (10.0 mg/kg, i.p.) or paroxetine (10.0 mg/kg, i.p.) along with VD3 (5.0 mg/kg, s.c.) produces distinct effects on the depression-like behavior in long-term OVX/CUMS rats. Co-administration of fluoxetine (10.0 mg/kg, i.p.) with VD3 did not facilitate the antidepressant-like effects of fluoxetine in the long-term OVX rats with CUMS. On the other hand, co-treatment with paroxetine with VD3 resulted in faster and marked antianhedonic- and antidepressant-like effects in long-term OVX rats with CUMS as compared to treatment with paroxetine alone. The co-administration of paroxetine and VD3 attenuates stress-induced modifications of CS/E2 levels in the serum, as well as- proinflammatory cytokine/NF-kB/5-HT levels in the hippocampus of long-term OVX rats exposed to CUMS. Conclusion: Supplementation of VD3 (5.0 mg/kg, s.c.)to paroxetine (10.0 mg/kg, i.p.) facilitates antianhedonic- and antidepressant-like effects of paroxetine in adult long-term OVX rats exposed to CUMS.

Fluoxetine increases analgesic effects of morphine, prevents development of morphine tolerance and dependence through the modulation of L-type calcium channels expression in mice

Here, we aimed to investigate the effects of fluoxetine on morphine-induced analgesia, as well as preventive effects of it on morphine induced tolerance and dependence in mice. We also elucidate the involvement of L-type Ca2+ channels in these phenomena.To induce morphine tolerance, mice were treated with morphine (50 mg/kg) for 3 consecutive days. To evaluate the involvement of the calcium channel in the effects of fluoxetine (5, 20 mg/kg), combination ineffective doses of the two L-type calcium channel blockers, nimodipine (5 mg/kg) or diltiazem (20 mg/kg) with flouxetine were used with each morphine dose. Nociceptive behavior was evaluated using hot-plate test, while physical dependence assessed by naloxone-precipitated withdrawal on the fourth day of experiment. The expression of Cav1.2 and Cav1.3 subunits of the L-type calcium channels in cortex and mesolimbic tissues were measured using western immunoassay.Results showed that co-administration of fluoxetine (20 mg/kg) with morphine increased its acute analgesia effect and prevented the induction of morphine antinociceptive tolerance and physical dependence in mice. Moreover, these effects was potentiated by pre-treatment with diltiazem or nimodipine. Results also showed up-regulation of the Cav1.3 and Cav1.2 expression in the cerebral cortex and mesolimbic regions through the development of morphine dependence. Moreover, chronic administration of fluoxetine with morphine reduced the observed up-regulation of Cav1.3 and Cav1.2 expression in cortex and mesolimbic tissues.Our data indicated that co-administering of fluoxetine with morphine could potentiate the antinociceptive effect of morphine, prevent morphine analgesia tolerance and attenuated the morphine withdrawal signs during induction phases. Moreover, we also pointed out for the first time the role of L-type Ca2+ channel channels in the modulatory effects of fluoxetine on the morphine-related effects.

Neither all anti-inflammatory drugs nor all doses are effective in accelerating the antidepressant-like effect of fluoxetine in an animal model of depression

IntroductionNon-steroidal anti-inflammatory drugs (NSAIDs) have been studied as possible adjunctive therapy in the treatment of depression. However, administering NSAIDs to increase the effectiveness of antidepressant has yielded inconsistent results. MethodsWe evaluated the effect of the co-administration of fluoxetine (5 mg/kg) and flurbiprofen (5 mg/kg) or fluoxetine (5 mg/kg) and celecoxib (5 mg/kg) in the chronic escape deficit (CED) model of depression after 7 days of treatment. The co-administration of fluoxetine plus acetylsalicylic acid (ASA, 45 mg/kg i.p.) was used as a positive control. Moreover, we tested the behavioral effect of different doses (45, 22.5, and 11.25 mg/Kg i.p.) of ASA as potentiating agent of the effect of fluoxetine in the same paradigm. ResultsOur study showed that only the co-administration of ASA with fluoxetine was able to revert the stress-induced condition of escape deficit after 7 days of treatment, and that the amplitude of the antidepressant-like effect of ASA was dose dependent. In the same experimental conditions, celecoxib with fluoxetine only partially resolved the stress-induced impaired behavior while flurbiprofen/fluoxetine cotreatment was ineffective. LimitationsOur study is still exploratory, more doses, longer treatment regimens, and different behavioral outcomes must be investigated to draw a clear conclusion. ConclusionOur results further stress the importance of the type and dose when NSAIDs are associated with antidepressants to ameliorate a clinical response.

The 5-HT1B serotonin receptor regulates methylphenidate-induced gene expression in the striatum: Differential effects on immediate-early genes.

Drug combinations that include a psychostimulant such as methylphenidate (Ritalin) and a selective serotonin reuptake inhibitor such as fluoxetine are indicated in several medical conditions. Co-exposure to these drugs also occurs with "cognitive enhancer" use by individuals treated with selective serotonin reuptake inhibitors. Methylphenidate, a dopamine reuptake inhibitor, by itself produces some addiction-related gene regulation in the striatum. We have demonstrated that co-administration of selective serotonin reuptake inhibitors potentiates these methylphenidate-induced molecular effects, thus producing a more "cocaine-like" profile. There is evidence that the 5-HT1B serotonin receptor subtype mediates some of the cocaine-induced gene regulation. We thus investigated whether the 5-HT1B receptor also modifies methylphenidate-induced gene regulation, by assessing effects of a selective 5-HT1B receptor agonist (CP94253) on immediate-early gene markers ( Zif268, c- Fos, Homer1a) in adolescent male rats. Gene expression was measured by in situ hybridization histochemistry. Our results show that CP94253 (3, 10 mg/kg) produced a dose-dependent potentiation of methylphenidate (5 mg/kg)-induced expression of Zif268 and c- Fos. This potentiation was widespread in the striatum and was maximal in lateral (sensorimotor) sectors, thus mimicking the effects seen after cocaine alone, or co-administration of fluoxetine. However, in contrast to fluoxetine, this 5-HT1B agonist did not influence methylphenidate-induced expression of Homer1a. CP94253 also potentiated methylphenidate-induced locomotor activity. These findings indicate that stimulation of the 5-HT1B receptor can enhance methylphenidate (dopamine)-induced gene regulation. This receptor may thus participate in the potentiation induced by fluoxetine (serotonin) and may serve as a pharmacological target to attenuate methylphenidate + selective serotonin reuptake inhibitor-induced "cocaine-like" effects.

Effect of Fluoxetine Administration on Clinical and Echocardiographic Findings in Patients with Mitral Valve Prolapse and Generalized Anxiety Disorder: Randomized Clinical Trial

BackgroundMitral valve prolapse (MVP) is accompanied by mental disorders including anxiety, which has similar presentations as MVP. It is hypothesised that treatment of anxiety might reduce the symptoms of MVP.ObjectiveThe aim of this study was to assess the clinical and echocardiographic effects of fluoxetine administration in patients with MVP and anxiety.MethodsThis randomized clinical trial was conducted on patients with documented MVP and generalised anxiety disorder (GAD) who were referred to Mashhad University of Medical Sciences cardiology clinics, Mashhad, Iran in 2015. Subjects were randomly assigned to intervention group who received propranolol and fluoxetine (both at 10 mg/day) and control group who received 10 mg/day propranolol. Assessments included echocardiography and GAD-7 questionnaire and rating of chest pain, that were performed at baseline and then weekly for 4 weeks. Analysis was performed using the Mann-Whitney U test and Two-way Repeated Measures Analysis of Variance (ANOVA).ResultsSixty patients (25 male/ 35 female) with a mean age of 22.9 ± 2.5 years were studied in two groups of intervention (n = 30) and control (n = 30). GAD score was significantly higher in the intervention group (17.37 ± 1.61) compared with the control group (14.17 ± 0.83) (p<0.001). No significant difference was observed for changes in left atrium diameter, mitral annular diameter, left ventricular diameter or ejection fraction (p>0.05). Pain severity was reduced significantly more in control group (3.27 ± 1.26) compared to intervention group (2.80 ± 0.85) after treatment (p<0.001).ConclusionsThis study revealed that the co-administration of fluoxetine and propranolol may not only have no effective in improving echocardiographic changes of MVP but may also aggravate subjective findings of patients with MVP and GAD.Trial registrationThe trial is registered at the Iranian Clinical Trial Registry (IRCT.ir) with the IRCT identification number IRCT2014102819721N1.FundingThis research has been financially supported by Research Council of Sabzevar University of Medical Sciences.

English

The highly selective serotonin reuptake inhibitors are successful in the treatment of depression mood and anxiety disorders. The objective of this study is to investigate the effect of fluexotine and buspirone when given orally in three dose levels (5, 10 and 15 mg/ kg) not only for eight weeks on gastric lesions and oxidative markers in normal rats' mucosal integrity, but also for four weeks on gastric mucosal lesions in rats treated with indomethacin- induced ulcers. The results of this study showed that in normal rats, the administration of fluoxetine induced gastric lesions while buspirone caused no lesions. The indomethacin administration resulted in the development of gastric mucosal lesions. Furthermore, co-administration of fluoxetine and indomethacin enhanced the development of gastric mucosal lesions that were coupled with disturbance in antioxidant status. Buspirone, in contrast, significantly decreased the development of gastric mucosal lesions in rats treated with indomethacin. In conclusion, fluoxetine caused the development of gastric mucosal lesions and aggravate the effect of indomethacin to induce ulcer, however, buspirone had a protective effect that may be attributed to its antioxidant properties. Key words: Fluoxetine, buspirone, peptic ulcer, indomethacin-induced ulcer, oxidative stress.

Pre-clinical evaluation of CYP 2D6 dependent drug-drug interactions between primaquine and SSRI/SNRI antidepressants.

BackgroundThe liver-stage anti-malarial activity of primaquine and other 8-aminoquinoline molecules has been linked to bio-activation through CYP 2D6 metabolism. Factors such as CYP 2D6 poor metabolizer status and/or co-administration of drugs that inhibit/interact with CYP 2D6 could alter the pharmacological properties of primaquine.MethodsIn the present study, the inhibitory potential of the selective serotonin reuptake inhibitor (SSRI) and serotonin norepinephrine reuptake inhibitor (SNRI) classes of antidepressants for CYP 2D6-mediated primaquine metabolism was assessed using in vitro drug metabolism and in vivo pharmacological assays.ResultsThe SSRI/SNRI classes of drug displayed a range of inhibitory activities on CYP 2D6-mediated metabolism of primaquine in vitro (IC50 1–94 μM). Fluoxetine and paroxetine were the most potent inhibitors (IC50 ~1 µM) of CYP 2D6-mediated primaquine metabolism, while desvenlafaxine was the least potent (IC50 ~94 µM). The most potent CYP 2D6 inhibitor, fluoxetine, was chosen to investigate the potential pharmacological consequences of co-administration with primaquine in vivo. The pharmacokinetics of a CYP 2D6-dependent primaquine metabolite were altered upon co-administration with fluoxetine. Additionally, in a mouse malaria model, co-administration of fluoxetine with primaquine reduced primaquine anti-malarial efficacy.ConclusionsThese results are the first from controlled pre-clinical experiments that indicate that primaquine pharmacological properties can be modulated upon co-incubation/administration with drugs that are known to interact with CYP 2D6. These results highlight the potential for CYP 2D6-mediated drug–drug interactions with primaquine and indicate that the SSRI/SNRI antidepressants could be used as probe molecules to address the primaquine-CYP 2D6 DDI link in clinical studies. Additionally, CYP 2D6-mediated drug–drug interactions can be considered when examining the possible causes of human primaquine therapy failures.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1329-z) contains supplementary material, which is available to authorized users.

Interactive effects of selected pharmaceutical mixtures on bioaccumulation and biochemical status in crucian carp (Carassius auratus)

The aim of this study was to evaluate the interactive effects of fluoxetine (FLU), roxithromycin (ROX) and propranolol (PRP) on the bioaccumulation and biochemical responses in the crucian carp Carassius auratus. After 7 days of binary exposure (ROX + FLU and PRP + FLU), the addition of waterborne FLU at nominal concentrations of 4, 20 and 100 μg L−1 significantly increased the accumulation of ROX and PRP in fish livers in most cases, although elevated ROX and PRP bioaccumulation levels were not observed in muscles or gills. The inductive response of 7-ethoxyresorufin O-deethylase (EROD) to PRP and that of 7-benzyloxy-4-trifluoromethyl-coumarin O-dibenzyloxylase (BFCOD) to ROX were inhibited by the co-administration of FLU at all tested concentrations. Correspondingly, marked inhibition of CYP1A and CYP3A mRNA expression levels was observed in the livers of fish co-treated with FLU + PRP and FLU + ROX relative to their PRP- and ROX-only counterparts, respectively. In addition, as reflected by superoxide dismutase (SOD) activity and malondialdehyde (MDA) content, co-exposure to ROX + FLU and PRP + FLU seemed to induce stronger antioxidant responses than single pharmaceutical exposure in fish livers. This work indicated that the interactive effects of pharmaceutical mixtures could lead to perturbations in the bioaccumulation and biochemical responses in fish.

Behavioral, endocrine, and neuronal alterations in zebrafish (Danio rerio) following sub-chronic coadministration of fluoxetine and ketamine

Most existing pharmacological treatments have focused on the “monoamine hypothesis” for targeted drug design for major depressive disorder (MDD). Many of these medications have a delayed onset-of-action and limited efficacy. Antidepressants with principal targets outside the monoamine system may offer the potential for more rapid activity with improved therapeutic benefit. Growing evidence suggests that the glutamatergic system is uniquely central to the neurobiology and treatment of MDD. Ketamine (Ketalar®) is a non-competitive glutamatergic antagonist classically used to induce sedation. However, preliminary clinical evidence has been promising with regard to its rapidly acting antidepressant profile. Zebrafish (Danio rerio) have emerged as a promising new animal model to screen the effects of numerous psychotropic compounds. This study aimed to determine if a sub-chronic low (sub-anesthetic) dose of ketamine could be used to augment the antidepressant effects of the widely used antidepressant fluoxetine (Prozac®) in adult zebrafish, employing an ethanol withdrawal model. Sub-chronic exposure to dosages of 100μg/L fluoxetine and 20mg/L of ketamine reduced anxiety/depression-like behaviors, leads to upregulation of serotonin synthesis and elevated whole-body cortisol levels. These results demonstrate the utility of zebrafish as a model for neuropharmacological research, and the possible efficacy of fluoxetine and ketamine coadministration.

Teratogenic Effects of Coadministration of Fluoxetine and Olanzapine on Rat Fetuses

Objective. Depression during pregnancy is a relatively common problem. Since little is known about the teratogenic effects of concomitant administration of fluoxetine and olanzapine during the organogenesis period, the aim of the present study was to evaluate the teratogenic effects of coadministration of fluoxetine and olanzapine on rat fetuses. Method. Forty-two pregnant rats were divided into seven groups, randomly. The first group received 0.5 mL of normal saline as the control. The second and third groups received fluoxetine at doses of 9 mg/kg and 18 mg/kg, respectively. Olanzapine was injected at 3 mg/kg and 6 mg/kg to the fourth and fifth groups, respectively. The sixth group received 9 mg/kg fluoxetine and 3 mg/kg olanzapine. Finally, the seventh group was administrated with fluoxetine and olanzapine at 18 mg/kg and 6 mg/kg, respectively. Drugs were injected intraperitoneally between day eight and day 15 of the pregnancy. On the 17th day of pregnancy, the fetuses were removed and micro-/macroscopically studied. Results. Fetuses of rats receiving high doses of these drugs showed a significant rate of cleft palate development, premature eyelid opening and torsion anomalies, compared to the control group (P ≤ 0.01). It is concluded that these drugs can lead to teratogenicity, so their concomitant use during pregnancy should be avoided, or if necessary their doses must be decreased.

Disruption of 5-HT2A Receptor-PDZ Protein Interactions Alleviates Mechanical Hypersensitivity in Carrageenan-Induced Inflammation in Rats

Despite common pathophysiological mechanisms, inflammatory and neuropathic pain do not respond equally to the analgesic effect of antidepressants, except for selective serotonin reuptake inhibitors (SSRIs), which show a limited efficacy in both conditions. We previously demonstrated that an interfering peptide (TAT-2ASCV) disrupting the interaction between 5-HT2A receptors and its associated PDZ proteins (e.g. PSD-95) reveals a 5-HT2A receptor-mediated anti-hyperalgesic effect and enhances the efficacy of fluoxetine (a SSRI) in diabetic neuropathic pain conditions in rats. Here, we have examined whether the same strategy would be useful to treat inflammatory pain. Sub-chronic inflammatory pain was induced by injecting λ-carrageenan (100 µl, 2%) into the left hind paw of the rat. Mechanical hyperalgesia was assessed after acute treatment with TAT-2ASCV or/and fluoxetine (SSRI) 2.5 h after λ-carrageenan injection. Possible changes in the level of 5-HT2A receptors and its associated PDZ protein PSD-95 upon inflammation induction were quantified by Western blotting in dorsal horn spinal cord. Administration of TAT-2ASCV peptide (100 ng/rat, intrathecally) but not fluoxetine (10 mg/kg, intraperitoneally) relieves mechanical hyperalgesia (paw pressure test) in inflamed rats. This anti-hyperalgesic effect involves spinal 5-HT2A receptors and GABAergic interneurons as it is abolished by a 5-HT2A antagonist (M100907, 150 ng/rat, intrathecally) and a GABAA antagonist, (bicuculline, 3 µg/rat, intrathecally). We also found a decreased expression of 5-HT2A receptors in the dorsal spinal cord of inflamed animals which could not be rescued by TAT-2ASCV injection, while the amount of PSD-95 was not affected by inflammatory pain. Finally, the coadministration of fluoxetine does not further enhance the anti-hyperalgesic effect of TAT-2ASCV peptide. This study reveals a role of the interactions between 5-HT2A receptors and PDZ proteins in the pathophysiological pathways of inflammatory pain and opens new perspectives in its control thanks to molecules disrupting 5-HT2A receptor/PDZ protein interactions.

A benzodiazepine impairs the neurogenic and behavioural effects of fluoxetine in a rodent model of chronic stress

Antidepressant agents such as fluoxetine have been shown to produce neurogenic effects involving transcriptional and translational changes that direct molecular and cellular plasticity. These cellular and molecular events appear necessary to mediate the therapeutic effects of fluoxetine and may be generated through the ability for fluoxetine to regulate BDNF levels. Clinically, benzodiazepines are frequently used in combination with standard antidepressants both for initial treatment and maintenance therapy, especially when comorbid anxiety is present. However, very little is known regarding the consequence of combined treatment of benzodiazepines and antidepressant on the development of clinical effect. The current study therefore examined the effect of co-administration of fluoxetine and the benzodiazepine, diazepam, on hippocampal neurogenesis in the social isolation rodent model of chronic stress. We demonstrate that 9 weeks of social isolation induces a deficit in motivational behaviour with increased anxiety as well as impairment in hippocampal neurogenesis. This was parallelled by reduced BDNF levels in the hippocampus. While treatment with fluoxetine alone for 3 weeks restored anxiety behaviour as well as progenitor cell proliferation and the generation of new hippocampal neurons, this effect was prevented by co-administration with diazepam. This suggests that co-administering benzodiazepines with antidepressants could significantly delay or prevent the cellular and behavioural improvement needed by patients. These findings indicate the need for future clinical studies designed to investigate the combined effects of benzodiazepines and antidepressants in patients.

Co-administration of fluoxetine and Sildenafil has benefits in anxiety behavior in mice

Fluoxetine, a selective serotonin reuptake inhibitor, has been widely prescribed drugs in psychiatry. However, it may produce controversial effects, including sexual dysfunction. Sildenafil, a phosphodiesterase inhibitor type 5, may reduce fluoxetine-induced behavior alterations, but its drug interaction profile has not been investigated. To evaluate the interaction between sildenafil and fluoxetine, we acutely or chronically administered adult male mice with intraperitoneal sildenafil (2 mg/kg); fluoxetine (10 mg/kg); a mixture of fluoxetine (10 mg/kg) and sildenafil (2 mg/kg); the anxiolytic benzodiazepine, diazepam (0.3 mg/kg); or saline, after which the mice were evaluated in an elevated plus-maze. The number of entries into the open arms, the time spent in the open arms, and the numbers of total entries into the arms were determined as measures of anxiety. Acute treatment with fluoxetine produced a behavioral profile consistent with anxiogenesis, while sildenafil produced an anxiolytic-like profile. Co-administration of fluoxetine with sildenafil reversed the anxiogenic effects of the former. In chronic treatment neither of drugs (alone) had any effects compared to controls. Their combination resulted in anxiolytic effect. These findings suggest that the anxiolytic sildenafil masked the effect of fluoxetine in the chronic experiment.

Investigation of drug–drug interactions between clopidogrel and fluoxetine

Drug-drug interactions may contribute to the variability of the response of clopidogrel. Several hypotheses have been proposed concerning the potential modification of clopidogrel pharmacokinetics and pharmacodynamics by fluoxetine. This open-label crossover study assessed the effect of fluoxetine on the pharmacological activity of clopidogrel in healthy volunteers. Eight healthy male volunteers received a single 600-mg loading dose of clopidogrel followed by 20 mg of fluoxetine on 4 days and then 20 mg of fluoxetine plus 600 mg of clopidogrel on the fifth day. Eleven blood samples were withdrawn after clopidogrel administration to determine plasma concentrations of clopidogrel active metabolite (CAM) and platelet function. Platelet aggregation was measured by light transmittance aggregometry (LTA) and platelet reactivity index by flow cytometric vasodilator-stimulated phosphoprotein (VASP) analysis. The areas under the curve and maximum plasma concentrations of CAM were, respectively, 20.6 and 25.3% lower after co-administration of fluoxetine compared with administration of clopidogrel alone. The percentage maximum platelet aggregation values in the presence of 5 μM and 10 μM adenosine diphosphate, measured by LTA, were, respectively, 13.9 and 22.4% lower after fluoxetine co-administration. The platelet reactivity index measured by the flow cytometric VASP method was 36.8% lower when clopidogrel was administered in conjunction with fluoxetine.

Effect of co-treatment with fluoxetine or mirtazapine and risperidone on the active behaviors and plasma corticosterone concentration in rats subjected to the forced swim test

BackgroundSeveral clinical reports have postulated a beneficial effect of the addition of a low dose of risperidone to the ongoing treatment with antidepressants in treatment-resistant depression. MethodsThe present study aimed to examine the effect of treatment with fluoxetine or mirtazapine, given separately or jointly with risperidone, on active behavior and plasma corticosterone level in male Wistar rats subjected to the forced swim test (FST). ResultsThe obtained results showed that fluoxetine (5mg/kg), mirtazapine (5 and 10mg/kg) or risperidone (0.05 and 0.1mg/kg) did not change the active behavior of rats in the FST. However, co-treatment with fluoxetine (10mg/kg) and risperidone (0.1mg/kg) induced an antidepressant-like effect in that test because it significantly increased the swimming time and decreased the immobility time, while combined treatment with mirtazapine at 5 and 10mg/kg and risperidone at 0.05 and 0.1mg/kg evoked a significant increase in the swimming time and also climbing, and decreased the immobility time. WAY 100635 (a 5-HT1a receptor antagonist) at a dose of 0.1mg/kg inhibited the antidepressant-like effect induced by co-administration of fluoxetine or mirtazapine and risperidone. Active behavior in that test did not reflect an increase in general activity, since combined treatment with fluoxetine or mirtazapine and risperidone failed to enhance the exploratory activity of rats. Co-treatment with fluoxetine or mirtazapine and risperidone did not reduce the stress-induced increase in plasma corticosterone concentration in animals subjected to the FST. ConclusionThe obtained results indicate that risperidone applied in a low dose enhances the antidepressant-like activity of fluoxetine and mirtazapine in the FST (but does not normalize the stress-induced increase in corticosterone level in these rats), and that 5-HT1a receptors may play some role in these effects.

Effects of co-administration of fluoxetine and risperidone on properties of peritoneal and pleural macrophages in rats subjected to the forced swimming test

BackgroundLiterature data show that administration of atypical antipsychotic drug, risperidone (RIS), enhances antidepressive action of fluoxetine (FLU). As antidepressive treatments also regulate immune functions, we examined whether combined administration of FLU and RIS to rats subsequently subjected to a forced swimming test (FST) modifies parameters of macrophage activity that are directly related to their immunomodulatory functions, i.e., arginase (ARG) activity and nitric oxide (NO) synthesis. MethodsAntidepressive action of the drugs was assessed with FST. Peritoneal and pleural cells were eluted and selected parameters of immunoreactivity were assessed colorimetrically. ResultsWe found that the concomitant administration of FLU (10mg/kg) and RIS (0.1mg/kg) produced antidepressive-like effects in the FST, whereas the drugs were ineffective if administered separately. Stress related to the FST affected immune cell redistribution and changed some of the metabolic and immunomodulatory properties of macrophages. FLU administered to rats at a suboptimal dose for antidepressive action potently influenced macrophage immunomodulatory properties and redirected their activity toward antiinflammatory M2 functional phenotype, as manifested by changes in the ARG/NO ratio. These effects resulted from a direct cellular influence of the drug, as well as its action via neuroendocrine pathways, as evidenced in peritoneal and pleural cells. Addition of RIS did not augment immunomodulatory action of FLU, though the combination showed antidepressant-like activity in the FST. ConclusionsOur results suggest that when the drugs were administered together, FLU was potent enough to redirect macrophages toward M2 activity. It is also postulated that drug-induced changes in the immune system are not so closely related to antidepressant-like effects or might be secondary to those produced in the neuroendocrine system.