Enhanced long-term synaptic depression in an animal model of depression.

BACKGROUND: A growing body of evidence suggests a disturbance of brain plasticity in major depression. In contrast to hippocampal neurogenesis, much less is known about the role of synaptic plasticity. Long-term potentiation (LTP) and long-term depression (LTD) regulate the strength of synaptic transmission and the formation of new synapses in many neural networks. Therefore, we examined the modulation of synaptic plasticity in the chronic mild stress animal model of depression. METHODS: Adult rats were exposed to mild and unpredictable stressors for 3 weeks. Thereafter, long-term synaptic plasticity was examined in the hippocampal CA1 region by whole-cell patch clamp measurements in brain slices. Neurogenesis was assessed by doublecortin immunostaining. RESULTS: Exposure to chronic mild stress facilitated LTD and had no effect on LTP. Chronic application of the antidepressant fluvoxamine during the stress protocol prevented the facilitation of LTD and increased the extent of LTP induction. Neurogenesis in the dentate gyrus was impaired after chronic stress. CONCLUSIONS: In addition to neurogenesis, long-term synaptic plasticity is an important and ubiquitous form of brain plasticity that is disturbed in an animal model of depression. Facilitated depression of synaptic transmission might impair function and structure of brain circuits involved in the pathophysiology of major depression. Antidepressants might counteract these alterations.     

丁螺环酮对难治性强迫症治疗的增效作用

目的：比较氟伏沙明合并丁螺环酮与氟伏沙明治疗难治性强迫症的疗效。方法：将符合条件的60例难治性强迫症患者随机分成两组,分别给与氟伏沙明合并丁螺环酮（合用组）和氟伏沙明（对照组）,进行12周的系统治疗,使用Yale—Brown强迫量表（Y—BOCS）,汉密尔顿焦虑量表（HAMA）评估其疗效;以治疗中出现的症状量表（TESS）和有关的实验室检查评定不良反应。结果：治疗以后丽组患者的Y-BOCS评分均明显下降,合用组的治疗效果较好,两组之间差异存在显著性（P〈0．01）,并且合用组起效快;而两组HAMA量表的评分明显下降,合用组的治疗效果较好,两组之间差异存在显著性（P〈0．01）,合用组起效快;合用组的不良反应发生率高于对照组,但差异无显著性;两组药物引起的不良反应均为轻度或中度,表现有所不同,患者耐受性好。结论：氟伏沙明合并丁螺环酮治疗难治性强迫症的疗效优于单独使用氟伏沙明组,且合用组起效较快,不良反应较轻。     

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

Background and purpose:

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.

Experimental approach:

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.

Key results:

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).

Conclusions and implications:

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.     

Obsessive–compulsive disorder

Obsessive–compulsive disorder is a well-defined clinical syndrome which has been very difficult to treat with standard psychotherapies and medications. There is a ‘hidden epidemic’ of silent sufferers who will begin seeking treatment as general knowledge of the efficacy of serotinin reuptake inhibitor antidepressants and behavioral therapy becomes widespread. The serotonin model requires us to reconceptualize the monoamine reuptake inhibitors as more than antidepressants and raises the issue of whether there is a commonality in the biology of compulsions, impulsivity, bulimia, and suicide.     

Different inhibitory effect of fluvoxamine on omeprazole metabolism between CYP2C19 genotypes

AIMS: Omeprazole is mainly metabolized by the polymorphic cytochrome P450 (CYP) 2C19. The inhibitory effect of fluvoxamine, an inhibitor of CYP2C19 as well as CYP1A2, on the metabolism of omeprazole was compared between different genotypes for CYP2C19. METHODS: Eighteen volunteers, of whom six were homozygous extensive metabolizers (EMs), six were heterozygous EMs and six were poor metabolizers (PMs) for CYP2C19, participated in the study. A randomized double-blind, placebo-controlled crossover study was performed. All subjects received two six-day courses of either daily 50 mg fluvoxamine or placebo in a randomized fashion with a single oral 40 mg dose of omeprazole on day six in both cases. Plasma concentrations of omeprazole and its metabolites, 5-hydroxyomeprazole, omeprazole sulphone, and fluvoxamine were monitored up to 8 h after the dosing. RESULTS: During placebo administration, geometric means of peak concentration (C(max)), under the plasma concentration-time curve from 0 to 8 h (AUC(0,8 h)) and elimination half-life (t(1/2)) of omeprazole were 900 ng ml(-1), 1481 ng ml(-1) h, and 0.6 h in homozygous EMs, 1648 ng ml(-1), 4225 ng ml(-1) h, and 1.1 h in heterozygous EMs, and 2991 ng ml(-1), 11537 ng ml(-1) h, and 2.8 h in PMs, respectively. Fluvoxamine treatment increased C(max) of omeprazole by 3.7-fold (95%CI, 2.4, 5.0-fold, P < 0.01) and 2.0-fold (1.4, 2.6-fold, P < 0.01), AUC(0,8 h) by 6.0-fold (3.3, 8.7-fold, P < 0.001) and 2.4-fold (1.7, 3.2-fold, P < 0.01), AUC(0, infinity ) by 6.2-fold (3.0, 9.3-fold, P < 0.01) and 2.5-fold (1.6, 3.4-fold, P < 0.001) and prolonged t((1/2)) by 2.6-fold (1.9, 3.4-fold, P < 0.001) and 1.4-fold (1.02, 1.7-fold, P < 0.05), respectively. However, no pharmacokinetic parameters were changed in PMs. The AUC(0,8 h) ratios of 5-hydroxyomeprazole to omeprazole were decreased with fluvoxamine in homozygous EMs (P < 0.05) and heterozygous EMs (P < 0.01). CONCLUSIONS: Even a low dose of fluvoxamine increased omeprazole exposure in EMs, but did not increase omeprazole exposure in PMs after a single oral dose of omeprazole. These findings confirm a potent inhibitory effect of fluvoxamine on CYP2C19 activity. The bioavailability of omeprazole might, to some extent, be increased through inhibition of P-glycoprotein during fluvoxamine treatment.     

Fluvoxamine and sleep disturbances in posttraumatic stress disorder

This study assesses the efficacy of fluvoxamine treatment on different domains of subjective sleep quality in Vietnam combat veterans with chronic posttraumatic stress disorder (PTSD). Medically healthy male Vietnam theater combat veterans (N = 21) completed a 10-week open label trial. Fluvoxamine treatment led to improvements in PTSD symptoms and all domains of subjective sleep quality. The largest effect was for dreams linked to the traumatic experience in combat. In contrast, generic unpleasant dreams showed only a modest response to treatment. Sleep maintenance insomnia and the item troubled sleep showed a large treatment response, whereas sleep onset insomnia improved less substantially. These therapeutic benefits contrast with published reports that have found activating effects of Selective Serotonin Reuptake Inhibitors on the sleep electroencephalogram.     

Fluvoxamine versus fluoxetine in major depressive episode: a double-blind randomised comparison

A double-blind, multinational study was conducted to compare the efficacy and safety of fluvoxamine and fluoxetine in outpatients with major depressive episode; 184 patients were randomised to fluvoxamine (100 mg/day) or fluoxetine (20 mg/day) for 6 weeks. Both drugs were effective and there were no statistically significant differences between them in the area under the curve of change from baseline in the Hamilton depression rating scale (HAMD) total score. However, the percentage of HAMD responders (>or= 50% decrease in HAMD total score) at week 2, the clinical global improvement severity of illness score at week 2 and the depression subscale of the irritability, depression and anxiety scale at weeks 1, 2 and 4, all showed significant advantages for fluvoxamine. During the last 2 weeks, fluvoxamine was significantly more effective in improving the HAMD sleep disturbance scale. Both drugs were well tolerated and there were no marked differences in their side effect profiles which were typical of SSRIs. Fluvoxamine and fluoxetine have similar efficacy and safety profiles in the treatment of major depressive episode; the findings of this study indicate that fluvoxamine may have a faster onset of action with respect to resolution of depressive symptoms and result in a better improvement in sleep quality.     

A Double-Blind Comparison of Fluvoxamine Versus Placebo in the Treatment of Compulsive Buying Disorder

Nondepressed outpatients with a compulsive buying disorder were recruited by advertisement and word of mouth for inclusion in a controlled treatment trial. Following a 1-week single-blind placebo washout, subjects were randomly assigned to fluvoxamine (n = 12) or placebo (n = 11). Subjects received fluvoxamine (up to 300 mg daily) or placebo for 9 weeks. There were few dropouts. Outcome measures included the Yale–Brown Obsessive-Compulsive Scale—Shopping Version (YBOCS-SV), three Clinical Global Impressions (CGI) ratings, the Hamilton Rating Scale for Depression (HRSD), and the Maudsley Obsessive-compulsive Inventory (MOI). At the conclusion of the trial, 50% of fluvoxamine recipients and 63.6% of placebo recipients achieved CGI ratings of much or very much improvement, while 33% of fluvoxamine recipients were very much improved compared with 18% of placebo recipients (by endpoint analysis). Subjects in both treatment cells showed improvement as early as the second week of the trial, and for most, improvement continued during the 9-week study. There were no significant differences between fluvoxamine- and placebo-treated subjects on any of the outcome measures, with the exception that fluvoxamine recipients achieved greater improvement than placebo recipients on the MOI (p = .02). Adverse experiences were more frequent in the group receiving fluvoxamine, particularly nausea, insomnia, decreased motivation, and sedation. We conclude that in a short-term treatment trial of compulsive buying, subjects receiving fluvoxamine or placebo respond similarly.     

Enantioselective disposition of lansoprazole in relation to CYP2C19 genotypes in the presence of fluvoxamine

AIMS: Lansoprazole is affected by polymorphism of CYP2C19. The aim of this study was to examine the effects of fluvoxamine, a CYP2C19 inhibitor, on the pharmacokinetics of each lansoprazole enantiomer among three different CYP2C19 genotype groups. METHODS: Eighteen healthy subjects, of whom six each were homozygous extensive metabolizers (homEMs), heterozygous extensive metabolizers (hetEMs), or poor metabolizers (PMs) for CYP2C19, participated in the study. Each subject received either placebo or fluvoxamine, 25 mg twice daily for 6 days, then a single oral dose of 60 mg of racemic lansoprazole. The plasma concentrations of lansoprazole enantiomers and lansoprazole sulphone were subsequently measured for 24 h post lansoprazole administration using liquid chromatography. RESULTS: In the homEMs and hetEMs, fluvoxamine significantly increased the AUC(0, infinity) and C(max) and prolonged the elimination half-life of both (R)- and (S)-lansoprazole, whereas in the PMs, the only statistically significant effect of fluvoxamine was on the AUC(0, infinity) for (R)-lansoprazole. The mean fluvoxamine-mediated percent increase in the AUC(0, infinity) of (R)-lansoprazole in the homEMs compared with the PMs was significant (P = 0.0117); however, C(max) did not differ among the three CYP2C19 genotypes. On the other hand, fluvoxamine induced a significant percent increase in both the AUC(0, infinity) and C(max) for (S)-lansoprazole in the homEMs compared with the hetEMs (P = 0.0007 and P = 0.0125, respectively) as well as compared with the PMs (P < 0.0001 for each parameter). The mean R : S ratio for AUC(0, infinity) of lansoprazole in the homEMs was significantly different between the placebo and the fluvoxamine treatment groups (12.7 (9.1, 16.8) vs 6.4 (5.4, 7.4), respectively, P < 0.0001), though not in the PMs (5.5 (4.3, 6.7) vs 5.9 (5.3, 6.5), respectively). CONCLUSIONS: The magnitude of the contribution of CYP2C19 to the metabolism of (S)-lansoprazole is much greater compared with that of the (R)-enantiomer. In extensive metabolizers, hepatic CYP2C19 plays an important role in the absorption and elimination of lansoprazole, particularly the (S)-enantiomer.     

Actigraphy can measure antidepressant-induced daytime sedation in healthy volunteers

Actigraphy is the continuous measurement of the motor component of behaviour. A change in behaviour will result in a change in activity. Drugs that are behaviourally toxic will cause changes in activity which can be measured using an actigraph. It is hypothesized that a reduction in daytime activity is a measure of sedation. A study was conducted comparing actigraphy with valid, reliable psychometric tests which are sensitive to the behaviourally toxic effects of psychoactive drugs. The study was designed to investigate whether actigraphy could accurately measure the daytime sedation associated with tricyclic antidepressants. The effects of fluvoxamine and dothiepin on behavioural activity and psychomotor abilities, in 12 healthy male volunteers, was investigated in a placebo-controlled, double-blind, crossover study. Subjects completed a battery of psychometric tests prior to dosing then at 1, 2, 3, 4 and 6 h post dose. Actigraphy showed that dothiepin caused daytime sedation, defined as a reduction in activity and this result was confirmed by the results from the psychometrics which showed that dothiepin impaired cognitive and psychomotor performance in the majority of the tests. These results show that actigraphy is capable of accurately measuring daytime sedation. © 1997 John Wiley & Sons, Ltd.