Incidence of serotonin syndrome in patients receiving tedizolid and concomitant serotonergic agents.

This study investigated the real-world incidence rate of serotonin syndrome in patients receiving tedizolid and concomitant serotonergic agents. A retrospective cohort of 479 adult patients was assessed between January 2015 and July 2023. Overall, a rare rate of 0.4% (2/479) of possible serotonin syndrome with tedizolid was identified. Given that concomitant serotonergic agents were commonly used, further study is warranted to determine causality.

Pharmacological rescue of Ras signaling, GluA1-dependent synaptic plasticity, and learning deficits in a fragile X model.

Fragile X syndrome, caused by the loss of Fmr1 gene function, is the most common form of inherited mental retardation, with no effective treatment. Using a tractable animal model, we investigated mechanisms of action of a few FDA-approved psychoactive drugs that modestly benefit the cognitive performance in fragile X patients. Here we report that compounds activating serotonin (5HT) subtype 2B receptors (5HT2B-Rs) or dopamine (DA) subtype 1-like receptors (D1-Rs) and/or those inhibiting 5HT2A-Rs or D2-Rs moderately enhance Ras-PI3K/PKB signaling input, GluA1-dependent synaptic plasticity, and learning in Fmr1 knockout mice. Unexpectedly, combinations of these 5HT and DA compounds at low doses synergistically stimulate Ras-PI3K/PKB signal transduction and GluA1-dependent synaptic plasticity and remarkably restore normal learning in Fmr1 knockout mice without causing anxiety-related side effects. These findings suggest that properly dosed and combined FDA-approved psychoactive drugs may effectively treat the cognitive impairment associated with fragile X syndrome.

Role of 5-HT receptors in neuropathic pain: potential therapeutic implications.

5-HT plays a crucial role in the progress and adjustment of pain both centrally and peripherally. The therapeutic action of the 5-HT receptors` agonist and antagonist in neuropathic pain have been widely reported in many studies. However, the specific roles of 5-HT subtype receptors have not been reviewed comprehensively. Therefore, we summarized the recent findings on multiple subtypes of 5-HT receptors in both central and peripheral nervous system in neuropathic pain, particularly, 5-HT1, 5-HT2, 5-HT3 and 5-HT7 receptors. In addition, 5-HT4, 5-HT5 and 5-HT6 receptors were also reviewed. Most of studies focused on the function of 5-HT subtype receptors in spinal level compared to brain areas. Based on these evidences, the pain process can be facilitated or inhibited that depending on the specific subtypes and the distribution of 5-HT receptors. Therefore, this review may provide potential therapeutic implications in treatment of neuropathic pain.

Serotonergic system may be involved in alterations of sleep homeostasis in spontaneously hypertensive rats.

Hypertension is associated with sleep disorders. Spontaneously hypertensive rats are derived from Wistar-Kyoto rats and widely used in research on hypertension. The present study investigated the propensity to sleep and electroencephalographic spectrum changes over 24 hr in spontaneously hypertensive rats, and proposed the involvement of the serotonergic system in these alterations. Time-course analysis showed that spontaneously hypertensive rats exhibit hyperarousal during the light phase but hypersomnia during the dark phase. Spontaneously hypertensive rats also exhibited less slight fluctuation in electroencephalographic delta power density over 24 hr as compared with Wistar-Kyoto rats, suggesting that the accumulation or elimination of sleep pressure was disrupted. Sleep deprivation disrupted the regulation of sleep homeostasis in spontaneously hypertensive rats, reflected by less sleep time and poor sleep quality during the recovery period. The density and activity of serotonergic neurons in the dorsal raphe nucleus were higher in spontaneously hypertensive rats compared with Wistar-Kyoto rats. Interestingly, we observed the absence of fluctuations in 5-hydroxytryptamine and 5-hydroxyindoleacetic acid across the sleep, wake, sleep deprivation and sleep recovery stages in spontaneously hypertensive rats, which were dramatically different from Wistar-Kyoto rats. These results indicate that the disruption of sleep-wake pattern and sleep homeostasis in spontaneously hypertensive rats might be related to abnormalities of the serotonergic system.

Use of the French healthcare insurance database to estimate the prevalence of exposure to potential drug-drug interactions.

PURPOSE: Drug-drug interactions (DDIs) require monitoring in an aging population with increasing polypharmacy exposure. We aimed to estimate the prevalence of exposure to potential DDIs using the French healthcare insurance system database, for six DDIs with various clinical relevance: angiotensin II receptor blockers or angiotensin-converting enzyme inhibitors and nonsteroidal anti-inflammatory drugs (ARBs-ACEIs + NSAIDs), antiplatelet agents and NSAIDs (AAP + NSAIDs), serotonergic drugs and tramadol (SD + T), statins and macrolides (S + M), oral anticoagulant and NSAIDs (OAC + NSAIDs), and colchicine and macrolides (C + M). METHODS: We used exhaustive healthcare data from a 1/97th random sample of the population covered by the French health insurance system (EGB) between 2006 and 2016. Exposure to a DDI was defined as overlapping exposure to two interacting drugs. The prevalence of exposure was estimated by year. RESULTS: Prevalence of exposure in 2016 was estimated at 3.7% for ARBs-ACEIs + NSAIDs, 1.5% for AAP + NSAIDs, 0.76% for SD + T, 0.36% for S + M, 0.24% for AOC + NSAIDs, and 0.02% for C + M. In 26% to 58% of episodes of exposure, the two interacting drugs were prescribed by the same physician and dispensed by the same pharmacy the same day. Between 2006 and 2016, the yearly prevalence was increasing for SD + T and for DDIs involving NSAIDs, and it was decreasing for those involving macrolides. CONCLUSION: Exposures to potential DDIs in France are not uncommon with a high proportion resulting from a co-prescription by the same physician. Monitoring the prevalence of exposure to DDIs is needed to implement prevention measures. Administrative data enable this surveillance in large and representative cohorts.

Modulation of the Paracrine Kynurenic System in Bone as a New Regulator of Osteoblastogenesis and Bone Mineral Status in an Animal Model of Chronic Kidney Disease Treated with LP533401.

An increase in the peripheral synthesis of serotonin and kynurenine, observed during the chronic kidney disease (CKD) course, is negatively associated with bone health. Serotonin and kynurenine are connected by the common precursor, tryptophan. LP533401 is an inhibitor of peripheral serotonin synthesis. This study aimed to establish if the inhibition of serotonin synthesis by LP533401 may affect the kynurenine pathway activity in bone tissue and its potential consequence with regard to osteogenesis and bone mineral status. Nephrectomized rats were treated with LP533401 at a dose of 30 and 100 mg/kg daily for eight weeks. Tryptophan and kynurenine concentrations were determined, and tryptophan 2,3-dioxygenase (TDO) expression was assessed. We discovered the presence of a TDO-dependent, paracrine kynurenic system in the bone of rats with CKD. Its modulation during LP533401 treatment was associated with impaired bone mineral status. Changes in TDO expression affecting the kynurenine pathway activity were related to the imbalance between peripheral serotonin and 25-hydroxyvitamin D. There were also close associations between the expression of genes participating in osteoblastogenesis and activation of the kynurenine pathway in the bones of LP53301-treated rats. Our results represent the next step in studying the role of tryptophan metabolites in renal osteodystrophy.

Fenfluramine, a serotonin-releasing drug, prevents seizure-induced respiratory arrest and is anticonvulsant in the DBA/1 mouse model of SUDEP.

OBJECTIVE: Prevention of sudden unexpected death in epilepsy (SUDEP) is a critical goal for epilepsy therapy. The DBA/1 mouse model of SUDEP exhibits an elevated susceptibility to seizure-induced death in response to electroconvulsive shock, hyperthermia, convulsant drug, and acoustic stimulation. The serotonin hypothesis of SUDEP is based on findings that treatments which modify serotonergic function significantly alter susceptibility to seizure-induced sudden death in several epilepsy models, including DBA/1 mice. Serotonergic abnormalities have also recently been observed in human SUDEP. Fenfluramine is a drug that enhances serotonin release in the brain. Recent studies have found that the addition of fenfluramine improved seizure control in patients with Dravet syndrome, which has a high incidence of SUDEP. Therefore, we investigated the effects of fenfluramine on seizures and seizure-induced respiratory arrest (S-IRA) in DBA/1 mice. METHODS: The dose and time course of the effects of fenfluramine (i.p.) on audiogenic seizures (Sz) induced by an electric bell in DBA/1 mice were determined. Videos of Sz-induced behaviors were recorded for analysis. Statistical significance (P < 0.05) was evaluated using the chi-square test. RESULTS: Sixteen hours after administration of 15 mg/kg of fenfluramine, a high incidence of selective block of S-IRA susceptibility (P < 0.001) occurred in DBA/1 mice without blocking any convulsive behavior. Thirty minutes after 20-40 mg/kg of fenfluramine, significant reductions of seizure incidence and severity, as well as S-IRA susceptibility occurred, which were long-lasting (≥48 hours). The median effective dose (ED50 ) of fenfluramine for significantly reducing Sz at 30 minutes was 21 mg/kg. SIGNIFICANCE: This study presents the first evidence for the effectiveness of fenfluramine in reducing seizure incidence, severity, and S-IRA susceptibility in a mammalian SUDEP model. The ability of fenfluramine to block S-IRA selectively suggests the potential usefulness of fenfluramine in prophylaxis of SUDEP. These results further confirm and extend the serotonin hypothesis of SUDEP.

Dose-Finding Study of Lorexys for Hypoactive Sexual Desire Disorder in Premenopausal Women.

INTRODUCTION: Prior medication treatment for hypoactive sexual desire disorder (HSDD) in women has left about half the subjects without benefit. Lorexys (LOR), a proprietary combination of the stimulating/excitatory dopamine-norepinephrine reuptake inhibitor bupropion (BUP) and the sedating/inhibitory serotonergic agonist-antagonist trazodone (TRZ), was developed as a multifunctional solution for this problem. AIM: Test efficacy, safety, and tolerability of LOR in a range of doses in a combined phase IB/IIA study in premenopausal outpatients with HSDD. METHODS: Otherwise healthy premenopausal women from 25-50 years of age with HSDD were tested in an open-label, active-control, one-way crossover study, with three 4-week treatments of extended-release TRZ and/or sustained-release BUP. Evaluations were made before and after each treatment. A washout of at least a week followed each treatment. The order of treatments was a standard dose of BUP; a subtherapeutic dose of BUP and TRZ (LOR-low); and a threshold-therapeutic dose of BUP and TRZ (LOR-mod). A midpoint interim analysis was planned to consider adapting doses for efficacy or safety. MAIN OUTCOME MEASURE: The primary efficacy measure was the Female Sexual Function Index, Desire domain; the main secondary efficacy measures included the Female Sexual Distress Scale-Revised 13th item, on bother about low desire, and a Patient's Global Impression of Change. The main outcome comparison was the proportions of responders. Safety measures were elicited adverse events, Epworth Sleepiness Scale, Columbia Suicide Severity Rating Scale 6-item SCREEN version, vital signs, electrocardiograms, and standard laboratory tests. RESULTS: Interim analysis did not require altering doses. Most evaluable subjects responded to LOR-mod (at the standard thresholds for response based on minimum clinically relevant difference from baseline, 79% on Female Sexual Function Index, Desire domain, 87% on Female Sexual Distress Scale-Revised Item 13, and 79% on Patient's Global Impression of Change; each P < .05 vs BUP). As expected, close to half responded to BUP (38%, 45%, and 52%, respectively). Response to LOR-low was intermediate (not significant vs BUP). Sensitivity analyses to compensate for carryover effects supported the efficacy of LOR-mod. Elicited adverse events showed the expected profile of TRZ, but led to no sedative-type dropouts or worsening on the Epworth Sleepiness Scale. CLINICAL IMPLICATIONS: The open-label 1-way crossover design of this phase IB/IIA study limits conclusions, but the consistency of responder analyses showing superiority of LOR-mod dose over control, and the lack of central depressant dropouts, favor further development in double-blind placebo-control trials. STRENGTH & LIMITATIONS: Strengths include large margins of efficacy over control agent, rapid onset of action, and rigorous safety assessment. Limitations are open-label, cross-over design/lack of placebo control and 1-month duration of exposure. CONCLUSION: Moderate-dose LOR was generally well-tolerated and was significantly more effective than BUP (active control). The results seem highly favorable compared to previously tested agents. Pyke RE, Clayton AH. Dose-Finding Study of Lorexys for Hypoactive Sexual Desire Disorder in Premenopausal Women. J Sex Med 2019;16:1885-1894.

Emerging drugs for the treatment of Dravet syndrome.

Introduction: Dravet syndrome (DS) is an early-onset genetic developmental epileptic encephalopathy characterized by multiple seizure types which are refractory to antiseizure medication. There is an unmet need for effective and tolerable drugs to control different seizure types in DS types, with the aim of improving quality of life and preventing neurological impairment. Areas covered: Narrative review of efficacy and tolerability of fenfluramine, cannabidiol (CBD), verapamil, and modulators of serotonin signaling pathways (lorcaserin or trazodone) in the treatment of DS. Expert opinion/commentary: A recent large randomized controlled trial has shown that CBD is effective in the treatment of DS; preliminary data from the placebo-controlled trial on fenfluramine are also promising. Further studies are definitely required to evaluate the role of verapamil and modulators of serotonin signaling in DS. At present, drugs used to treat seizures in DS treat the symptoms of epilepsy rather than its cause(s). Future research should focus on elucidating the natural history of DS and whether appropriate treatment can have a beneficial impact on its disease course. A multidisciplinary, individualized approach to care of DS patients is required.

Gender-specific risk factors for low bone mineral density in patients taking antipsychotics for psychosis.

OBJECTIVE: This study examined clinical and gender-specific risk factors for low bone mineral density (BMD) in adult patients with psychotic disorders. METHODS: The study included 285 community-dwelling patients with psychotic disorders. Dual-energy X-ray absorptiometry was used to measure BMD. Clinical characteristics associated with low BMD were identified with logistic regression analysis in total population and each gender. RESULTS: Fifty-eight (20.4%) subjects had low BMD. Low BMD was more common in men and in patients with low body mass indices (BMIs), as well as in those with shorter treatment durations, those on Medicaid, and patients using serotonergic antidepressants. Logistic regression analysis revealed that low BMD was negatively associated with BMI and treatment duration and positively with gender (male) and serotonergic antidepressants use in the overall population. In men, low BMD was associated with treatment duration and BMI; in women, low BMD was associated with BMI, prolactin level, vitamin D, and serotonergic antidepressant use. CONCLUSION: Managing the risk factors associated with low BMD among patients with psychotic disorder should be done gender-specifically. Psychotropic agents should be prescribed mindful of their effects on bone, as use of these medications is a modifiable risk factor for osteoporosis in women with psychotic disorders.

Anxiolytic and antidepressant activities of Pelargonium roseum essential oil on Swiss albino mice: Possible involvement of serotonergic transmission.

The anxiolytic and antidepressant activities of the Reunion Geranium (Pelargonium roseum Willd) essential oil (EO) were evaluated in male Swiss albino mice by intraperitoneal administration of 10, 20, and 50 mg/kg bw using elevated plus maze (EPM), open-field test (OFT), and forced swimming test (FST). Moreover, we evaluated whether the 5-HT1A and GABAA -benzodiazepine receptor systems are involved in the anxiolytic effects through the coadministration of WAY-100635 (a selective 5-HT1A receptor antagonist) and flumazenil (an antagonist of benzodiazepine). GC-MS revealed the monoterpene alcohols citronellol (35.9%) and geraniol (18.5%) as the main components of the P. roseum EO. EO was effective in increasing the total number of entries and time spent in the open arms of EPM whereas number of rearing in OFT was significantly decreased in comparison with the control. In the FST, immobility time decreased in EO treated mice. Pretreatment with WAY-100635, but not Flumazenil, was able to reverse the effects of the EO in the EPM and FST, indicating that the EO activity occurs via the serotonergic but not GABAergic transmission. Overall, results of this work showed significant anxiolytic and antidepressant activity of P. roseum EO and confirmed the traditional uses of Pelargonium species as calming agents.

Serotonin 5-HT2 receptor interactions with dopamine function: implications for therapeutics in cocaine use disorder.

Cocaine exhibits prominent abuse liability, and chronic abuse can result in cocaine use disorder with significant morbidity. Major advances have been made in delineating neurobiological mechanisms of cocaine abuse; however, effective medications to treat cocaine use disorder remain to be discovered. The present review will focus on the role of serotonin (5-HT; 5-hydroxytryptamine) neurotransmission in the neuropharmacology of cocaine and related abused stimulants. Extensive research suggests that the primary contribution of 5-HT to cocaine addiction is a consequence of interactions with dopamine (DA) neurotransmission. The literature on the neurobiological and behavioral effects of cocaine is well developed, so the focus of the review will be on cocaine with inferences made about other monoamine uptake inhibitors and releasers based on mechanistic considerations. 5-HT receptors are widely expressed throughout the brain, and several different 5-HT receptor subtypes have been implicated in mediating the effects of endogenous 5-HT on DA. However, the 5-HT2A and 5-HT2C receptors in particular have been implicated as likely candidates for mediating the influence of 5-HT in cocaine abuse as well as to traits (e.g., impulsivity) that contribute to the development of cocaine use disorder and relapse in humans. Lastly, new approaches are proposed to guide targeted development of serotonergic ligands for the treatment of cocaine use disorder.

A case study in identifying targeted patients population in major depressive disorder by enhanced enrichment design.

Despite advances in clinical trial design, failure rates near 80% in phase 2 and 50% in phase 3 have recently been reported. The challenges to successful drug development are particularly acute in central nervous system trials such as for pain, schizophrenia, mania, and depression because high-placebo response rates lessen assay sensitivity, diminish estimated treatment effect sizes, and thereby decrease statistical power. This paper addresses the importance of rigorous patient selection in major depressive disorder trials through an enhanced enrichment paradigm. This approach led to a redefinition of an ongoing, blinded phase 3 trial algorithm for patient inclusion (1) to eliminate further randomization of transient placebo responders and (2) to exclude previously randomized transient responders from the primary analysis of the double blind phase of the trial. It is illustrated for a case study for the comparison between brexpiprazole + antidepressant therapy and placebo + antidepressant therapy. Analysis of the primary endpoint showed that efficacy of brexpiprazole versus placebo could not be established statistically if the original algorithm for identification of placebo responders was used, but the enhanced enrichment approach did statistically demonstrate efficacy. Additionally, the enhanced enrichment approach identified a target population with a clinically meaningful treatment effect. Through its successful identification of a target population, the innovative enhanced enrichment approach enabled the demonstration of a positive treatment effect in a very challenging area of depression research.

Serotonergic Mechanisms Regulating the GI Tract: Experimental Evidence and Therapeutic Relevance.

Serotonin (5-hydroxytryptamine; 5-HT) is best known as a neurotransmitter critical for central nervous system (CNS) development and function. 95% of the body's serotonin, however, is produced in the intestine where it has been increasingly recognized for its hormonal, autocrine, paracrine, and endocrine actions. This chapter provides the most current knowledge of the critical autocrine and paracrine roles of 5-HT in intestinal motility and inflammation as well as its function as a hormone in osteocyte homeostasis. Therapeutic applications in each of these areas are also discussed.

[Psychotherapy with Adjuvant use of Serotonergic Psychoactive Substances: Possibilities and Challenges]. / Psychotherapie mit adjuvanter Gabe von serotonergen psychoaktiven Substanzen ­ Möglichkeiten und Hindernisse.

Background Recently, scientific interest in the therapeutic potential of serotonergic and psilocybin hallucinogens (psychedelics) such as lysergic acid diethylamide (LSD) and entactogens like 3,4-methylendioxymethamphetamine (MDMA) within the framework of psychotherapy has resumed. The present article provides an overview on the current evidence on substance-assisted psychotherapy with these substances. Method A selective search was carried out in the PubMed and Cochrane Library including studies investigating the clinical use of serotonergic psychoactive substances since 2000. Results Studies were found investigating the following indications: alcohol (LSD and psilocybin) and tobacco addiction (psilocybin), anxiety and depression in patients suffering from life-threatening somatic illness (LSD and psilocybin), obsessive-compulsive disorder (OCD) (psilocybin), treatment-resistant major depression (psilocybin), and posttraumatic stress disorder (PTSD) (MDMA). Discussion Substance use disorders, PTSD and anxiety and depression in patients suffering from life-threatening somatic illness belong to the indications with the best evidence for substance-assisted psychotherapy with serotonergic psychoactive agents. To date, studies indicate efficacy and relatively good tolerability. Further studies are needed to determine whether these substances may represent suitable and effective treatment options for some treatment-resistant psychiatric disorders in the future.

Serotonergic agents act on 5-HT3 receptors in the brain to block seizure-induced respiratory arrest in the DBA/1 mouse model of SUDEP.

Drugs that enhance the action of serotonin (5-hydroxytrypamine, 5-HT), including several selective serotonin reuptake inhibitors (SSRIs), reduce susceptibility to seizure-induced respiratory arrest (S-IRA) that leads to death in the DBA/1 mouse model of sudden unexpected death in epilepsy (SUDEP). However, it is not clear if specific 5-HT receptors are important in the action of these drugs and whether the brain is the major site of action of these agents in this SUDEP model. The current study examined the actions of agents that affect the 5-HT3 receptor subtype on S-IRA and whether intracerebroventricular (ICV) microinjection of an SSRI would reduce S-IRA susceptibility in DBA/1 mice. The data indicate that systemic administration of SR 57227, a 5-HT3 agonist, was effective in blocking S-IRA in doses that did not block seizures, and the S-IRA blocking effect of the SSRI, fluoxetine, was abolished by coadministration of a 5-HT3 antagonist, ondansetron. Intracerebroventricular administration of fluoxetine in the present study was also able to block S-IRA without blocking seizures. These findings suggest that 5-HT3 receptors play an important role in the block of S-IRA by serotonergic agents, such as SSRIs, which is consistent with the abnormal expression of 5-HT3 receptors in the brainstem of DBA mice observed previously. Taken together, these data indicate that systemically administered serotonergic agents act, at least, in part, in the brain, to reduce S-IRA susceptibility in DBA/1 mice and that 5-HT3 receptors may be important to this effect.

Mechanism of action of brexpiprazole: comparison with aripiprazole.

Brexpiprazole is a new therapeutic agent that was recently approved for the treatment of schizophrenia and for the adjunctive treatment of major depressive disorder. Brexpiprazole has features that both overlap and contrast with a related molecule, aripiprazole, and these features are discussed here.

[Vortioxetine: a new antidepressant to treat depressive episodes]. / La vortioxétine : un nouvel antidépresseur pour traiter les épisodes dépressifs caractérisés.

Vortioxetine is a new antidepressant, which mechanism of action is multimodal, targeting the 5-HT1A, 5-HT1B, 5-HT1D, 5-HT3, 5-HT7 receptors and the serotonin transporter (5-HTT). Its efficacy and safety were assessed in fourteen studies including more than 3700 patients with a major depressive episode and treated with vortioxetine. In short-term studies (8 weeks), vortioxetine is more efficacious than placebo in decreasing depressive symptoms as measured by the MADRS total score, response rate (vortioxetine: 53.2% vs placebo: 35.2%) and remission rate (vortioxetine: 29.2% vs placebo: 19.3%). In a long-term study (52 weeks), vortioxetine is also superior to placebo in preventing relapses and recurrences. Moreover, in second line treatment, after failure of a first line selective serotonin reuptake inhibitor (SSRI) or serotonin norepinephrin reuptake inhibitor (SNRI), vortioxetine is superior to agomelatine in improving depressive symptoms and achieving response and remission. Furthermore, the positive effects of vortioxetine on improvement of cognitive symptoms of major depressive episodes are particularly well established in several clinical trials. The tolerability profile of vortioxetine is favourable. The recommended daily posology of vortioxetine is 10mg/d. Vortioxetine is a new antidepressant drug with a multimodal mechanism of action, well-documented efficacy and safety profiles.

[The pharmacological basis of the serotonin system: Application to antidepressant response]. / Les bases de pharmacologie fondamentale du système sérotoninergique : application à la réponse antidépressive.

If serotonin (5-hydroxytryptamin [5-HT]) is well known for its role in mood regulation, it also impacts numerous physiological functions at periphery. Serotonin is synthetized at the periphery into the gut by intestinal enterochromaffin cells and in the central nervous system (CNS) in the raphe nucleus from the essential amino acid tryptophan. Physiological effects of 5-HT are mediated by about 15 serotoninergic receptors grouped into seven broad families (5-HT1, 5-HT2, 5-HT3, 5-HT4, 5-HT5, 5-HT6, 5-HT7 receptor families). Except 5-HT3 receptor, a ligand-gated ion channels, all the others are G protein-coupled receptors. Serotonin's homeostasis involves serotoninergic autoreceptor such as 5-HT1A, 5-HT1B, 5-HT1D, the enzymatic degradation of serotonin by monoamine oxidase A (MAO-A), and a transporter (serotoninergic transporter [SERT]). In the CNS, the SERT is a key target for various antidepressant drugs such as Selective Serotonin Reuptake Inhibitors (SSRI), Serotonin Norepinephrin Reuptake Inhibitors (SNRI) and tricyclics family. However, antidepressant activity of SERT inhibitors is not directly mediated by the SERT inhibition, but a consequence of postsynaptic 5-HT receptor activation following the increase in 5-HT levels in the synaptic cleft. In pharmacology, SSRIs are defined as indirect agonist of postsynaptic receptor. Among all the 5-HT receptors, 5-HT1A, 5-HT1B, 5-HT1D, 5-HT2B and 5-HT4 receptors activation would mediate antidepressant effects. In the meanwhile, 5-HT2A, 5-HT2C, 5-HT3, 5-HT6 and 5-HT7 receptors activation would induce opposite effects. The best serotoninergic antidepressant would directly activate 5-HT1A, 5-HT1B, 5-HT1D, 5-HT2B and 5-HT4 and would block 5-HT2A, 5-HT2C, 5-HT3, 5-HT6 and 5-HT7 receptor. If the chemical synthesis of such a compound may be compromised, SERT inhibition associated with the blockade of some but not all 5-HT receptor could shorten onset of action and/or improve antidepressant efficacy on the overall symptomatology of depression.

Chronic treatment with a tryptophan-rich protein hydrolysate improves emotional processing, mental energy levels and reaction time in middle-aged women.

Common pharmacological treatments of mood disorders aim to modulate serotonergic neurotransmission and enhance serotonin levels in the brain. Brain serotonin levels are dependent on the availability of its food-derived precursor essential amino acid tryptophan (Trp). We tested the hypothesis that delivery of Trp via food may serve as an alternative treatment, and examined the effects of a Trp-rich, bioavailable dietary supplement from egg protein hydrolysate on cognitive and emotional functions, mood state, and sleep quality. In a randomised, placebo-controlled, parallel trial, fifty-nine mentally and physically healthy women aged 45-65 years received placebo (n 30) or the supplement (n 29) (both as 0.5 g twice per d) for 19 d. Emotional processing was significantly changed by supplementation, exhibiting a shift in bias away from negative stimuli. The results for the Affective Go/No-Go Task exhibited a slowing of responses to negative words, suggesting reduced attention to negative emotional stimuli. The results for the Facial Emotional Expression Rating Task also supported a shift away from attention to negative emotions and a bias towards happiness. An increase in arousal-like symptoms, labelled 'high energy', shorter reaction times and a slight benefit to sustained attention were observed in the treated subjects. Finally, when the supplement was taken 60-90 min before bedtime, a feeling of happiness before going to bed was consistently reported. In summary, daily consumption of a low-dose supplement containing bioavailable Trp may have beneficial effects on emotional and cognitive functions.