Reuptake Inhibitor Fluvoxamine Research Articles

P02 - 367 - Qui non zelat, non amat — compulsive jealousy in young women

Qui non zelat, non amat. One who does not burn, does not love - as Saint Augustine states. Jealousy is a troublesome emotion dominating mankind for time beyond all memory.However, it seems to be unclear, what constitutes normal jealousy and where the boundaries of pathological jealousy should be drawn. From the phenomenological point of view, psychiatrists' attention has always been focused on delusional jealousy, as a psychotic symptom. Obsessional jealousy, where the thought has the quality of obsessional ideation, is the topic of much fewer publications. The first clearly defined cases of obsessional jealousy were published by Mooney in 1965. In 1979, Cobb defined jealous ruminations as obsessive thoughts with the resultant compulsive rituals of checking on spouse. In 2007, Agarwal conducted a Medline search and retrieved no more than 20 relevant publications on this topic.In this presentation the authors discuss the cases of 3 young (21–27-year-old) women. In all cases, pathological jealousy with clearly obsessive characteristics was the leading or only psychiatric symptom. Two women were successfully treated with low doses of selective serotonin reuptake inhibitors (sertralin and fluvoxamine, respectively), while in one case, because of adverse SSRI effects, reversible inhibitor of monoamine oxidase A was administered. Obsessive jealousy, in contrast to delusive one, often affects young people, causing severe difficulties in gender socialisation, lowering the chances of finding an appropriate conjugal partner, hereby markedly worsening the quality of life. Proper differential diagnosis is, however, essential for choosing an adequate and successful treatment option.

Serotonergic involvement in methamphetamine-induced locomotor activity: A detailed pharmacological study

The mechanism by which the psychostimulant methamphetamine (METH) increases locomotor activity may be attributable to indirect activation of serotonin (5-HT) and dopamine (DA) receptors. In the present study, the ability of the serotonin reuptake inhibitor fluvoxamine, 5-HT 1A, 5-HT 1B, 5-HT 2A and 5-HT 2C receptor antagonists WAY100635, GR127935, M100907 and SB242084, and the 5-HT 2C receptor agonists WAY163909 and Ro 60-0175 or the 5-HT synthesis inhibitor para-chlorophenylalanine (pCPA) to alter METH-induced hyperactivity was analysed. Further, for comparative purposes, the involvement of the DA D 1 and D 2 receptor antagonists SCH23390 and haloperidol, D 2 partial agonists terguride, (−)3PPP and aripiprazole and finally clozapine were assessed. Doses of pCPA that attenuated 5-HT levels reduced METH activity. The 5-HT 1B antagonist GR127935 had no effect on METH-induced locomotor activity but blocked that induced by MDMA. The 5-HT 1A antagonist WAY100635 reduced activity but this did not reach significance. In contrast, M100907 (minimal effective dose; MED = 0.125 mg/kg), WAY163909 (MED = 3 mg/kg), Ro 60-0175 (MED = 3 mg/kg), haloperidol (MED = 0.1 mg/kg), clozapine (MED = 5 mg/kg), aripiprazole (MED = 1 mg/kg), (−)3PPP (MED = 3 mg/kg), terguride (MED = 0.2 mg/kg) and SCH23390 (MED = 0.001325 mg/kg) attenuated METH-induced locomotor activity. Administration of 20 mg/kg fluvoxamine attenuated, while SB242084 (MED = 0.25 mg/kg) potentiated METH-induced activity. These results contribute significantly to the understanding of the mechanism of action of this psychostimulant and suggest for the first time, that METH-induced locomotor stimulation is modulated by 5-HT 2A and 5-HT 2C receptors, but demonstrate that 5-HT 1B receptors are not directly involved. The involvement of the dopaminergic system was also demonstrated.

The triple reuptake inhibitor DOV216,303 exhibits limited antidepressant-like properties in the differential reinforcement of low-rate 72-second responding assay, likely due to dopamine reuptake inhibition

There is a need for antidepressants with novel mechanisms of action. One approach has been to develop compounds that inhibit reuptake of all three monoamines in the central nervous system, for example DOV216,303. Differential reinforcement of low-rate (72-s) responding is a behavioral test that is predictive of antidepressant-like properties. The effects of antidepressant compounds belonging to multiple classes, the anxiolytic diazepam and the antipsychotic haloperidol, were assessed in the DRL-72s task. Subsequently, the antidepressant-like properties of acute DOV216,303 were assessed. The selective serotonin reuptake inhibitor fluvoxamine, the preferential norepinephrine reuptake inhibitor desipramine and the tricyclic antidepressant imipramine exhibited antidepressant-like properties in the DRL-72s task. The atypical antidepressant bupropion, which inhibits dopamine and norepinephrine reuptake, and the selective dopamine transporter inhibitor GBR12909, changed reinforcement and response rates and inter-response time distribution in an opposite direction compared with the antidepressant compounds tested. The antipsychotic haloperidol exhibited antidepressant-like properties by increasing reinforcement rate, but failed to alter inter-response time distribution. Diazepam did not change reinforcement or response rates or inter-response time distribution. The triple reuptake inhibitor DOV216,303 significantly enhanced reinforcement rate at one intermediate dose, but exhibited similar effects as bupropion and GBR12909 on inter-response time distribution. The studies identified limited antidepressant-like properties of the triple reuptake inhibitor DOV216,303, likely due to dopamine transporter inhibition counteracting the effects of norepinephrine and serotonin transporter inhibition.

Possible involvement of peripheral serotonin 5-HT3 receptors in fluvoxamine-induced emesis in Suncus murinus.

Selective serotonin reuptake inhibitors fluvoxamine and fluoxetine, as well as serotonin (5-HT), induced vomiting in Suncus murinus (a house musk shrew). Fluvoxamine- and fluoxetine-induced vomiting gradually decreased with their repeated administration. Vomiting induced by serotonin also decreased with repeated treatment with serotonin. In these shrews, fluvoxamine-induced vomiting was partially inhibited. Fluvoxamine might induce vomiting, at least partially, by indirectly activating peripheral 5-HT(3) receptors, since serotonin has been reported to induce vomiting by activating peripheral 5-HT(3) receptors and granisetron, a 5-HT(3) antagonist, partially suppressed fluvoxamine-induced vomiting in our previous finding. In addition, fluvoxamine-induced vomiting was impaired more effectively using a step-wise dose-up schedule of fluvoxamine than a fixed high-dose schedule. Therefore, a careful dosing strategy starting with a low dose might be effective for avoiding emesis associated with the clinical use of fluvoxamine.

Selective Serotonin Reuptake Inhibitors Potentiate the Rapid Antidepressant-Like Effects of Serotonin4 Receptor Agonists in the Rat

BackgroundWe have recently reported that serotonin4 (5-HT4) receptor agonists have a promising potential as fast-acting antidepressants. Here, we assess the extent to which this property may be optimized by the concomitant use of conventional antidepressants.Methodology/Principal FindingsWe found that, in acute conditions, the 5-HT4 agonist prucalopride was able to counteract the inhibitory effect of the selective serotonin reuptake inhibitors (SSRI) fluvoxamine and citalopram on 5-HT neuron impulse flow, in Dorsal Raphé Nucleus (DRN) cells selected for their high (>1.8 Hz) basal discharge. The co-administration of both prucalopride and RS 67333 with citalopram for 3 days elicited an enhancement of DRN 5-HT neuron average firing rate, very similar to what was observed with either 5-HT4 agonist alone. At the postsynaptic level, this translated into the manifestation of a tonus on hippocampal postsynaptic 5-HT1A receptors, that was two to three times stronger when the 5-HT4 agonist was combined with citalopram. Similarly, co-administration of citalopram synergistically potentiated the enhancing effect of RS 67333 on CREB protein phosphorylation within the hippocampus. Finally, in the Forced Swimming Test, the combination of RS 67333 with various SSRIs (fluvoxamine, citalopram and fluoxetine) was more effective to reduce time of immobility than the separate administration of each compound.Conclusions/SignificanceThese findings strongly suggest that the adjunction of an SSRI to a 5-HT4 agonist may help to optimize the fast-acting antidepressant efficacy of the latter.

Fluvoxamine pharmacokinetics in healthy elderly subjects and elderly patients with chronic heart failure

To investigate the effects of age and chronic heart failure (CHF) on the oral disposition kinetics of fluvoxamine. A single fluvoxamine dose (50 mg) was administered orally to 10 healthy young adults, 10 healthy elderly subjects and 10 elderly patients with CHF. Fluvoxamine concentration in plasma was measured for up to 96 h. With the exception of apparent distribution volume, ageing modified all main pharmacokinetic parameters of fluvoxamine. Thus, peak concentration was about doubled {31 +/- 19 vs. 15 +/- 9 ng ml(-1); difference [95% confidence interval (CI)] 16 (3, 29), P < 0.05}, and area under the concentration-time curve was almost three times higher [885 +/- 560 vs. 304 +/- 84 ng h ml(-1); difference (95% CI) 581 (205, 957), P < 0.05]; half-life was prolonged by 63% [21.1 +/- 6.2 vs. 12.9 +/- 6.4 h; difference (95% CI) 8.2 (2.3, 14.1), P < 0.01], and oral clearance was halved (1.12 +/- 0.77 vs. 2.25 +/- 0.66 l h(-1) kg(-1); difference (95% CI) -1.13 (-1.80, -0.46), P < 0.001]. A significant inverse correlation was consistently observed between age and oral clearance (r=-0.67; P < 0.001). The coexistence of CHF had no significant effect on any pharmacokinetic parameters in elderly subjects. Ageing results in considerable impairment of fluvoxamine disposition, whereas CHF causes no significant modifications. Therefore, adjustment of initial dose and subsequent dose titrations may be required in elderly subjects, whereas no further dose reduction is necessary in elderly patients with CHF.

Functional interactions between 5‐HT2A and presynaptic 5‐HT1A receptor‐based responses in mice genetically deficient in the serotonin 5‐HT transporter (SERT)

Despite decreased presynaptic 5-HT(1A) and altered 5-HT(2A) receptor function in genetically-deficient serotonin (5-HT) transporter (SERT) mice, the 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide maleate salt (WAY 100635) still induced head twitches in these mice, a well-established 5-HT(2A) receptor-mediated response. Interactions between 5-HT(1A) and 5-HT(2A) receptors were assessed using the head-twitch response following 5-HT(1A) and 5-HT(2A) receptor agonists and antagonists in SERT wild-type (+/+), heterozygous (+/-), and knockout (-/-) mice. The role of brain 5-HT availability in WAY 100635 induced head twitches was also examined. WAY 100635 induced head twitches in a SERT gene-dose dependent manner, inducing 5-fold more head twitches in SERT -/- versus SERT +/+ mice. In SERT -/- mice, inhibition of 5-HT synthesis with p-chlorophenylalanine (PCPA) markedly depleted tissue 5-HT in all five brain areas examined and abolished WAY 100635 induced head twitches. Further, the selective 5-HT reuptake inhibitor fluvoxamine increased WAY 100635 induced head twitches in SERT +/+ and +/- mice. Head twitches following the 5-HT(2A) receptor agonist (+/-)-2,5-dimethoxy-4-iodophenyl-2-aminopropane (DOI) were robust in SERT +/+ and +/- mice but much reduced in SERT -/- mice. DOI-induced head twitches were decreased by the 5-HT(1A) agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) in SERT +/+ and +/- mice. All drug-induced head twitches were blocked by the 5-HT(2A) receptor antagonist a-Phenyl-1-(2-phenylethyl)-4-piperidinemethanol (MDL 11,939). These data show that indirect activation of 5-HT(2A) receptors via blockade of presynaptic 5-HT(1A) receptors potentiated head-twitch responses, suggesting functional interactions between these receptors, interactions affected by altered 5-HT availability. Our findings strongly support the correlation of WAY 100635 induced head twitches with increased 5-HT availability, induced genetically or pharmacologically.

Involvement of the 5-HT 1A receptor in the anti-immobility effects of fluvoxamine in the forced swimming test and mouse strain differences in 5-HT 1A receptor binding

We previously demonstrated the presence of strain differences in baseline immobility time and sensitivity to the selective serotonin reuptake inhibitor (SSRI) fluvoxamine in five strains of mice (ICR, ddY, C57BL, DBA/2 and BALB/c mice). Furthermore, variations in serotonin (5-HT) transporter binding in the brain were strongly related to strain differences in baseline immobility and sensitivity to fluvoxamine. In the present study, we examined the involvement of the 5-HT 1A receptor in anti-immobility effects in DBA/2 mice, which show high sensitivity to fluvoxamine. The anti-immobility effects of fluvoxamine in DBA/2 mice were inhibited by the 5-HT 1A receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]- N-(2-pyridinyl)cyclohexanecarboxamide (WAY 100635). However, the 5-HT 1B receptor antagonist 3-[3-(dimethylamino)propyl]-4-hydroxy- N-[4-(4-pyridinyl)phenyl]benzamide (GR55562), the 5-HT 2 receptor antagonist 6-methyl-1-(methylethyl)-ergoline-8beta-carboxylic acid 2-hydroxy-1-methylpropyl ester (LY 53857), the 5-HT 3 receptor antagonist ondansetron and the 5-HT 4 receptor antagonist 4-amino-5-chloro-2-methoxy-benzoic acid 2-(diethylamino)ethyl ester (SDZ 205,557) did not influence the anti-immobility effects of fluvoxamine in DBA/2 mice. These results suggest that fluvoxamine-induced antidepressant-like effects in DBA/2 mice are mediated by the 5-HT 1A receptor. We analyzed 5-HT 1A receptor binding in the brains of five strains of mice. Strain differences in 5-HT 1A receptor binding were observed. 5-HT 1A receptor binding in brain was not correlated with baseline immobility time in the five strains of mice examined. These results suggest that, although the anti-immobility effects of fluvoxamine in DBA/2 mice are mediated by the 5-HT 1A receptor, strain differences in 5-HT 1A receptor binding are not related to variation in immobility time and responses to fluvoxamine.

Brugada syndrome ECG provoked by the selective serotonin reuptake inhibitor fluvoxamine

A patient with an SCN5A p.W822X nonsense mutation, localized in the transmembrane region DII-S4 of the Na(v)1.5 sodium channel and leading to a non-expression of the mutant allele, was prescribed the selective serotonin reuptake inhibitor (SSRI) fluvoxamine (Floxyfral), 100 mg per day. His normal baseline ECG changed to a characteristic Brugada-Type-1-ECG pattern. To investigate whether fluvoxamine may reduce the cardiac sodium current, the effect of this drug was studied on the wild-type voltage-gated cardiac sodium channel Na(v)1.5 stably expressed in HEK293 cells. Patch-clamp recording showed a 50% inhibition of the current at a concentration of 57.3 microM. In our patient, no arrhythmia occurred but the proarrhythmic potential of SSRI in patients with SCN5A mutations cannot be excluded. Therefore, we advise 12-lead ECG control after administering SSRI in these patients.

Imaging of Sigma1 Receptors in the Human Brain Using PET and [11C]SA4503

Sigma(1) receptors were imaged in living human brain by positron emission tomography (PET) using [(11)C] SA4503. A dynamic 90-min scan and kinetic analysis enabled quantification of receptor density in the brain. The sigma(1) receptors were distributed throughout the brain in normal subjects, but decreased in the frontal, temporal, and occipital lobes, cerebellum and thalamus in patients with early Alzheimer's disease and in the putamen in patients with Parkinson's disease. In addition, rates of receptor occupancy by the neuroleptic haloperidol and the selective serotonin reuptake inhibitor fluvoxamine were evaluated by [(11)C]SA4503-PET and found to be high. [(11)C]SA4503-PET is useful for studying the pathophysiology of neurological and psychiatric disorders such as schizophrenia and for evaluation of the pharmacodynamics of psychiatric drugs.

Activation Adverse Events Induced by the Selective Serotonin Reuptake Inhibitor Fluvoxamine in Children and Adolescents

The aim of this study was to examine the prevalence of activation cluster adverse events (AC-AEs) in youths treated with the selective serotonin reuptake inhibitor (SSRI) fluvoxamine for anxiety and the relationship of AC-AEs to SSRI blood levels. Data from the Research Units on Pediatric Psychopharmacology (RUPP) Anxiety Study were examined for 45 youths (22 active fluvoxamine, 23 placebo) treated for Diagnostic and Statistical Manual for Mental Disorders, 4(th) edition (DSM-IV) anxiety disorders at the Johns Hopkins University site with an 8-week forced-flexible titration schedule. As part of the double-blind placebo-controlled trial, AC-AEs were recorded by clinicians at weekly patient visits. AC-AEs were defined as hyperactivity, activation, and disinhibition. Demographic characteristics, daily doses, and week-8 blood levels were examined in relation to the presence of AC-AEs. The prevalence of AC-AE and time to first event were established for those who experienced this side effect. AC-AEs were found in 10 of 22 participants (45%) receiving fluvoxamine and only 1 of 23 in the placebo group (4%). The onset of AC-AEs occurred from week 1 to week 8, with the majority occurring at or before week 4. The mean fluvoxamine blood level at week 8 in subjects with AC-AEs was higher than in subjects without AC-AEs (n = 16, t = -2.61, p = 0.04). Neither the age of the participants nor family history of bipolar or anxiety disorder differed between those who did and did not develop an AC-AE. AC-AEs were common side effects of fluvoxamine, often appeared during the first 8 weeks of treatment, and were associated with higher fluvoxamine blood levels. Close monitoring for AC-AEs, not only when initiating SSRI treatment but also throughout dose titration, is recommended for early identification of activation.

Eine additive Therapie chronischer Schmerzen bei fortgeschrittener Gon-/Coxarthrose mit dem selektiven Serotonin-Reuptake-Hemmer Fluvoxamin (Fevarin®)

The aim of this study was to investigate the effectiveness and safety of the selective serotonin reuptake inhibitor fluvoxamine (Flevarin) in patients with a chronic pain syndrome due to hip and knee arthritis. We prospectively investigated 60 patients in a single-centre double-blind study. The group was divided into two groups (M1 fluvoxamine; M2 placebo) each containing 30 patients, age ranging from 30 to 80 years. During treatment results were evaluated using several scales once at the beginning (V1) followed by weekly evaluations (V1-V8) and one final investigation at the end of treatment (V9). The investigated medication consisted of 50-150 mg fluvoxamine. In addition other drugs such as NSAID were administered (diclofenac, piroxicam, ibuprofen). Both groups (M1 and M2) showed a reduction of pain during treatment using the visual analogue scale (VAS). However, no statistical difference was found between both groups concerning pain reduction at any time. A significant pain relief was monitored in the patients of the M1 group towards the end of treatment. Concerning the daily impairment because of pain measured by the Griss scale an improvement was seen in 70 % of the patients receiving fluvoxamine versus 44 % in patients receiving placebo. Additionally, an improvement in the M1 group was seen in the WOMAC scale and in factors such as pain, stiffness and mobility compared to the M2 group. Using the CGI scale, 56.6 % of the M1 group compared to 37.9 % of the M2 group were stating that their overall status had improved "much" or "very much" at the end of the treatment (V9). A depression had been excluded in all patients. No statistical differences were seen in the Bf scale (von Zerssen) during all evaluations (V1 to V9). During the whole study 127 side effects were registered in 49 patients. None of the 5 severe events were related to the investigated drug. Considering the good effects in combination with very few side effects, a positive cost-effectiveness relation for the usage of fluvoxamine can be stated in patients with chronic pain syndrome due to hip and knee arthritis.

Mouse strain differences in immobility and sensitivity to fluvoxamine and desipramine in the forced swimming test: Analysis of serotonin and noradrenaline transporter binding

Strain differences in immobility time in the forced swimming test were investigated in five strains of mice, namely, ICR, ddY, C57BL/6, DBA/2 and BALB/c mice. There were significant strain differences. The immobility times of ICR, ddY and C57BL/6 mice were longer than those of DBA/2 and BALB/c mice. Immobility times were not significantly related to locomotor activity in these strains. There were also differences in sensitivity to the selective serotonin reuptake inhibitor (SSRI) fluvoxamine. In ICR, ddY and C57BL/6 mice, fluvoxamine did not affect immobility time, while it reduced the immobility time of DBA/2 and BALB/c mice dose-dependently. The noradrenaline reuptake inhibitor desipramine decreased immobility time in all strains of mice. Serotonin (5-HT) transporter binding in the brains of all five strains of mice was also investigated. Analysis of 5-HT transporter binding revealed significant strain differences, being lower in DBA/2 and BALB/c mice than in other strains of mice. The amount of 5-HT transporter binding was correlated to baseline immobility time. However, there was no significant relation between noradrenaline transporter binding and immobility time. These results suggest that the duration of baseline immobility depends on the levels of 5-HT transporter binding, leading to apparent strain differences in immobility time in the forced swimming test. Furthermore, differences in 5-HT transporter binding may cause variations in responses to fluvoxamine.

Transient suppression of progenitor cell proliferation through NMDA receptors in hippocampal dentate gyrus of mice with traumatic stress experience

Post-traumatic stress disorder is a long-lasting psychiatric disease after the traumatic experience of severe fatal stress with the consequence of hippocampal atrophy. Freezing behaviors were more than quintupled on the fear-conditioning test in mice previously subjected to water immersion restrain stress (WIRS) with metronome tones when determined 1-28 days after WIRS, while these mice exhibited the increased immobility time on the forced swimming test with the increased spontaneous locomotion. Prior experience of WIRS led to a transient decrease in subsequent 5-bromo-2'-deoxyuridine (BrdU) incorporation into proliferating cells in the hippocampal dentate gyrus. These behavioral and neurochemical alterations were significantly prevented by the daily injection of the tricyclic antidepressant imipramine and the selective serotonin reuptake inhibitor fluvoxamine, respectively. Moreover, WIRS significantly decreased the number of cells holding BrdU without affecting the differentiation ratio to astroglial and neuronal lineages 28 days later. Prior administration of an NMDA receptor antagonist significantly prevented the aforementioned changes by WIRS. These results suggest that NMDA receptors may play a role in mechanisms underlying the crisis of a variety of psychiatric symptoms relevant to post-traumatic stress disorder through transient suppression of neural progenitor cell proliferation in the murine hippocampal dentate gyrus.

Selective serotonin reuptake inhibitors fluvoxamine and paroxetine restore forced exercise-induced temperature dysregulation in ovariectomized mice

Hot flushes are one of the most frequent symptoms in menopausal women. Selective serotonin reuptake inhibitors (SSRIs) are considered to be first-line therapy for the treatment of hot flushes in women for whom hormone therapy is contraindicated. Recently, we have proposed forced exercise-induced flushing of tail skin in ovariectomized mice as a new experimental model of temperature dysregulation in menopausal hot flushes. In the present study, to validate this animal model as a tool for testing potential compounds for the treatment of menopausal hot flushes, we examined the effects of two SSRIs (fluvoxamine and paroxetine) on forced exercise-induced flushing of tail skin in ovariectomized mice, and compared it with that of estradiol replacement (1 mg/kg/week for 3 weeks, i.m.). Treatment with fluvoxamine (20 mg/kg, i.p.) or paroxetine (10 mg/kg, i.p.) completely inhibited forced exercise-induced flushing of tail skin in ovariectomized mice, and the effect of each was comparable to that of estradiol replacement. It is believed that the present findings provide the first experimental evidence to support the anti-flushing effects of SSRIs, such as fluvoxamine and paroxetine, in a clinical setting. An animal model with forced exercise probably serves as a useful experimental tool for evaluating the effects of different agents on hot flushes.

The selective serotonin reuptake inhibitor fluvoxamine suppresses post-feeding hyperactivity induced by food restriction in rats

Previous studies demonstrated that rats allowed access to running wheel with food restriction schedules run excessively. This hyperactivity consisted of a pre-feeding activity (an increase in running activity before the feeding time, also termed food-anticipatory activity: FAA) and a post-feeding activity (an increase in running activity after the feeding time, succeeding activity: SA). Here we evaluated the effect of fluvoxamine, a selective serotonin reuptake inhibitor, on food restriction-induced hyperactivity in rats. Furthermore, the effect of fluvoxamine on each of the FAA and the SA was also investigated. Rats were individually housed in a running-wheel cage under food restriction for 3 h per day, and running activity was measured for 7 consecutive days. This restricted feeding significantly increased the running activity and decreased body weight. Simultaneous administration of fluvoxamine (50 mg/kg/day, p.o.) for 7 days suppressed the increase in running activity ( P < 0.05) with no modification of the decrease in body weight or food intake. Analysis of each activity revealed that fluvoxamine's efficacy was observed only in the SA ( p < 0.01). These results suggest that repeated treatment with fluvoxamine attenuates the hyperactivity, which is exclusively dependent on the substantial reduction in the SA.

Antidepressants inhibit interferon-γ-induced microglial production of IL-6 and nitric oxide

Circumstantial evidence has suggested that activated microglia may be associated with the pathogenesis of depression. Pro-inflammatory cytokines may also be involved. Therefore, we examined the effects of various types of antidepressants, as well as the mood-stabilizer lithium chloride, on interferon-γ (IFN-γ)-induced microglial production of the pro-inflammatory mediators interleukin-6 (IL-6) and nitric oxide (NO). Treatment of the murine microglial 6-3 cells with 100 U/ml of IFN-γ resulted in an eightfold increase in IL-6 and a tenfold increase in NO into the culture medium. Pretreatment with the selective serotonin reuptake inhibitor fluvoxamine, the relatively selective noradrenaline reuptake inhibitor reboxetine, or the non-selective monoaminergic reuptake inhibitor imipramine, significantly inhibited IL-6 and NO production in a dose-dependent manner. These inhibitions were reversed significantly by SQ 22536, a cyclic adenosine monophosphate (cAMP) inhibitor, and, except for reboxetine, by the protein kinase A (PKA) inhibitor Rp-adenosine3′,5′-cyclic monophosphorothioate triethylammonium salt (Rp-3′,5′-cAMPS). Lithium chloride, which is believed to act by inhibiting the calcium-dependent release of noradrenaline, had a different spectrum of action on microglial 6-3 cells. It enhanced IFN-γ-stimulated IL-6 production and inhibited NO production. The inhibitory effect of lithium chloride was not reversed by either SQ 22536 or Rp-3′,5′-cAMPS. These results suggest that antidepressants have inhibitory effects on IFN-γ-activated microglia and these effects are, at least partially, mediated by the cAMP-dependent PKA pathway. On the other hand, the mood stabilizer and anti-manic agent lithium chloride has mixed effects on IFN-γ-induced microglial activation.

Involvement of the sigma 1 receptor in inhibiting activity of fluvoxamine on marble-burying behavior: Comparison with paroxetine

In the present study, we examined the involvement of the sigma 1 receptor in the inhibitory effect of the selective serotonin reuptake inhibitor (SSRI) fluvoxamine, compared with that of paroxetine, on marble-burying behavior, which is an animal model of obsessive–compulsive disorder. Sigma 1 receptor agonists (+)-SKF 10047 and PRE-084 significantly inhibited marble-burying behavior. Sigma receptor antagonist BD 1047 and selective sigma 1 receptor antagonist BD 1063 significantly attenuated the inhibition of marble-burying behavior by fluvoxamine. In contrast, selective sigma 2 receptor antagonist SM-21 failed to affect the inhibition of marble-burying behavior by fluvoxamine. On the other hand, BD 1047 and BD 1063 had no effect on the inhibition of marble-burying behavior by paroxetine. These observations show that activation of the sigma 1 receptor is a necessary component in the inhibitory effect of fluvoxamine on marble-burying behavior, and that the mechanism of its action is clearly different from that of paroxetine.

Serotonin transporter function, but not expression, is dependent on brain‐derived neurotrophic factor (BDNF): in vivo studies in BDNF‐deficient mice

In the present study, we used high-speed chronoamperometry to examine serotonin (5-HT) transporter (5-HTT) function in vivo in 2-, 5-, and 10-month-old brain-derived neurotrophic factor (BDNF)+/- mice. The rate of clearance of exogenously applied 5-HT was measured in CA3 region of hippocampus. In 2-month-old mice, the rate of 5-HT clearance did not differ between BDNF+/+ and BDNF+/- mice. In BDNF+/+ mice, 5-HT clearance rate (Tc) increased markedly with age. In contrast, Tc remained relatively static in BDNF+/- mice across 2-, 5-, and 10-month age groups. At 5 months of age, female BDNF+/+ mice had a lower maximal velocity (Vmax) for 5-HT clearance than male BDNF+/+ mice. There was a similar trend in 5-month-old BDNF+/- mice, but this did not reach statistical significance. There was an age-dependent increase in KT value for 5-HT clearance (i.e., decreased in vivo affinity of 5-HTT), but no significant effect of genotype or gender. 5-HTT density, as measured by [3H]cyanoimipramine binding, was not different between BDNF+/+ and BDNF+/- mice, although there was a significant increase in 5-HTT binding with age. The selective 5-HT reuptake inhibitor fluvoxamine (50 and 100 pmol) significantly decreased 5-HT clearance in BDNF+/+ mice, but not in BDNF+/- mice. Our data suggest that the profoundly reduced ability of 5- and 10-month-old BDNF+/- mice to clear 5-HT is not because of a decrease in the total number of 5-HTTs, but may be due to functional deficits in the 5-HTT, e.g., in the machinery/signaling required for insertion of 5-HTTs into the plasma membrane and/or activation of the 5-HTT once it is positioned to take up 5-HT from extracellular fluid.

Fluvoxamine effects on concurrent ethanol- and food-maintained behaviors.

In previous studies, the selective serotonin reuptake inhibitor fluvoxamine preferentially reduced responding for ethanol compared with responding for food under conditions in which each was available alone in separate groups or in the same subjects under a multiple schedule in which baseline response rates were matched. The impact of providing concurrent access to food on pharmacological effects on ethanol self-administration remains largely unexplored. In this study, acute doses of fluvoxamine (3.0-17.8 mg/kg) were administered 30 min before the experimental session to Lewis rats responding under a concurrent fixed-ratio, fixed-ratio schedule of ethanol and food presentation. Ratios for food were adjusted for each subject to provide matched rates of food and ethanol reinforcement across the 30-min session. Although the number of ethanol and food deliveries did not significantly differ under baseline conditions, response rates did differ. Following fluvoxamine administration, responding for food was decreased more than responding for ethanol. This differential effect did not appear to be related to response rate or fixed-ratio size. Thus, the selectivity of fluvoxamine on ethanol- versus food-maintained responding depends on the context in which the behavior occurs. Such results may help explain inconsistencies between preclinical results and those in humans, and could provide insight into the behavioral determinants of pharmacological effects on ethanol self-administration.