Trends in the development of new antidepressants. Is there a light at the end of the tunnel?

Exploring the Potential of Probiotics and Prebiotics in Major Depression: From Molecular Function to Clinical Therapy

Major depressive disorder (MDD) represents a complex and challenging mental health condition with multifaceted etiology. Recent research exploring the gut-brain axis has shed light on the potential influence of gut microbiota on mental health, offering novel avenues for therapeutic intervention. This paper reviews current evidence on the role of prebiotics and probiotics in the context of MDD treatment. Clinical studies assessing the effects of prebiotic and probiotic interventions have demonstrated promising results, showcasing improvements in depression symptoms and metabolic parameters in certain populations. Notably, prebiotics and probiotics have shown the capacity to modulate inflammatory markers, cortisol levels, and neurotransmitter pathways linked to MDD. However, existing research presents varied outcomes, underscoring the need for further investigation into specific microbial strains, dosage optimization, and long-term effects. Future research should aim at refining personalized interventions, elucidating mechanisms of action, and establishing standardized protocols to integrate these interventions into clinical practice. While prebiotics and probiotics offer potential adjunctive therapies for MDD, continued interdisciplinary efforts are vital to harnessing their full therapeutic potential and reshaping the landscape of depression treatment paradigms.

Antidepressant effects of coumarins and their derivatives: A critical analysis of research advances

Coumarins and their derivatives are non-flavonoids polyphenols with diverse pharmacological activities including anti-depressant effects. This study systematically examines the antidepressant effects of coumarins and their derivatives in relation to time series of research progress in the pharmacological pathways, association with other diseases, toxicity and bibliometric analysis. The review was approached using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) coupled with R package involving Biblioshiny, a web interface for Bibliometrix analysis and VOSviewer software analytic tools. Literature searches were conducted in Scopus, Web of Science, and PubMed from the inception through January 21, 2023. Coumarins, depression, coumarin derivatives and treatment were the main search terms used which resulted in the inclusion of 46 eligible publications. Scopoletin, psoralen, 7-hydroxycoumarin, meranzin hydrate, osthole, esculetin/umbelliferone were the most studied coumarins with antidepressant effects. Coumarins and their derivatives exerted antidepressant effects with a stronger affinity for monoamine oxidase-B (MAO-B) inhibition and, their inhibitory effect via neurotransmitter pathway on MAO is well-studied. However, epigenetic modification, neuroendocrine, neurotrophic pathways are understudied. Recent research focuses on their antidepressant effects which targeted cytokines and fibromyalgia. There is a link between the gut microbiome, the brain, and depression; meranzin hydrate exerts an antidepressant activity by remodelling the gastrointestinal system. We established that empirical data on some coumarins and their derivatives to support their antidepressant effects are limited. Likewise, the safe dose range for several coumarins and their derivatives is yet to be fully determined.

"In vivo biosynthesis of N,N-dimethyltryptamine, 5-MeO-N,N-dimethyltryptamine, and bufotenine in E.coli"

N,N-dimethyltryptamine (DMT), 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and 5-hydroxy-N,N-dimethyltryptamine (bufotenine) are psychedelic tryptamines found naturally in both plants and animals and have shown clinical potential to help treat mental disorders, such as anxiety and depression. Advances in both metabolic and genetic engineering make it possible to engineer microbes as cell factories to produce DMT and its aforementioned derivatives to meet demand for ongoing clinical study. Here, we present the development of a biosynthetic production pathway for DMT, 5-MeO-DMT, and bufotenine in the model microbe Escherichia coli. Through the application of genetic optimization techniques and process optimization in benchtop fermenters, the in vivo production of DMT in E. coli was observed. DMT production with tryptophan supplementation reached maximum titers of 74.7 ± 10.5 mg/L under fed batch conditions in a 2-L bioreactor. Additionally, we show the first reported case of de novo production of DMT (from glucose) in E. coli at a maximum titer of 14.0 mg/L and report the first example of microbial 5-MeO-DMT and bufotenine production in vivo. This work provides a starting point for further genetic and fermentation optimization studies with the goal to increase methylated tryptamine production metrics to industrially competitive levels.

Cost Effectiveness of Pharmacological and Non-pharmacological Treatments for Depression in Low- and Middle-Income Countries: A Systematic Literature Review

BACKGROUND

Various treatment approaches are available for depression. Given the scarcity of healthcare resources, it is important to optimise treatment availability in an efficient manner. Economic evaluations can inform the optimal allocation of healthcare resources. However, there is currently no review synthesising what is known about the cost effectiveness of treatments for depression in low- and middle-income countries (LMICs).

METHODS

This review identified articles from six database searches: APA PsycINFO, CINAHL Complete, Cochrane Library, EconLit, Embase and MEDLINE Complete. Trial- and model-based economic evaluations published between 1 January 2000 and 3 December 2022 were included. The quality of health economic studies (QHES) instrument was used to assess the quality of the included papers.

RESULTS

This review comprised 22 articles, with most studies (N = 17) focusing exclusively on the adult population. Even though evidence regarding the cost effectiveness of antidepressants for treating various forms of depression was inconsistent; an atypical antipsychotic (aripiprazole) was frequently reported to be cost effective for treatment-resistant depression. Task shifting (aka task sharing) to lay health workers or non-specialist health care providers appeared to be a cost-effective approach for treating depression in LMICs.

CONCLUSIONS

Overall, this review found mixed evidence on the cost effectiveness of depression treatment choices among LMICs, with some indication that task sharing with lay health workers may be cost effective. Future research will be needed to fill the gaps around the cost effectiveness of depression treatments in younger people and beyond healthcare facilities.

A cross-sectional study on the personality traits of episodic and chronic migraine patients

BACKGROUND

Migraine, is a common neurological disorder that may be associated with certain personality traits. This study aims to identify and compare the personality traits accompanying the clinical and sociodemographic profiles in migraine groups.

METHODS

The study included a cohort of chronic, episodic migraine (CM - EM) and healthy controls (HC). Migraine was diagnosed according to the International Classification of Headache Disorders-3β criteria. Age, gender, migraine-related disease duration, number of days with a headache each month, and headache intensity of the patients were recorded. The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) was used to determine personality traits.

RESULTS

The study groups were similar in terms of sociodemographic characteristics (70 CM, 70 EM, and 70 HC). The visual analog scale (VAS) score was significantly higher in CM (p < 0.05). No statistically significant difference was found between the groups concerning symptoms of migraine such as osmophobia, photophobia, phonophobia, and nausea (p > 0.05). When the personality traits were examined, the mean scores of the MMPI test results of migraine patients were found to be higher than healthy controls in line personality disorders (p < 0.05 for all personality traits). In CM patients, the 'hysteria' score was found to be higher in subgroup evaluation (p < 0.05).

CONCLUSION

EM and CM patients had more evidence of personality disorders than healthy controls. CM patients had higher hysteria scores than EM patients. In addition to pain treatment, determining personality traits and providing appropriate management with a multidisciplinary approach can benefit both in terms of treatment, cost, and time.

Endocannabinoid System: Chemical Characteristics and Biological Activity

The endocannabinoid system (eCB) has been studied to identify the molecular structures present in Cannabis sativa. eCB consists of cannabinoid receptors, endogenous ligands, and the associated enzymatic apparatus responsible for maintaining energy homeostasis and cognitive processes. Several physiological effects of cannabinoids are exerted through interactions with various receptors, such as CB1 and CB2 receptors, vanilloid receptors, and the recently discovered G-protein-coupled receptors (GPR55, GPR3, GPR6, GPR12, and GPR19). Anandamide (AEA) and 2-arachidoylglycerol (2-AG), two small lipids derived from arachidonic acid, showed high-affinity binding to both CB1 and CB2 receptors. eCB plays a critical role in chronic pain and mood disorders and has been extensively studied because of its wide therapeutic potential and because it is a promising target for the development of new drugs. Phytocannabinoids and synthetic cannabinoids have shown varied affinities for eCB and are relevant to the treatment of several neurological diseases. This review provides a description of eCB components and discusses how phytocannabinoids and other exogenous compounds may regulate the eCB balance. Furthermore, we show the hypo- or hyperfunctionality of eCB in the body and how eCB is related to chronic pain and mood disorders, even with integrative and complementary health practices (ICHP) harmonizing the eCB.

Increasing Adiponectin Signaling by Sub-Chronic AdipoRon Treatment Elicits Antidepressant- and Anxiolytic-Like Effects Independent of Changes in Hippocampal Plasticity

(1) Background: Adiponectin is an adipocyte-secreted hormone that has antidepressant- and anxiolytic-like effects in preclinical studies. Here, we investigated the antidepressant- and anxiolytic-like effects of sub-chronic treatment with AdipoRon, an adiponectin receptor agonist, and its potential linkage to changes in hippocampal adult neurogenesis and synaptic plasticity. (2) Methods: Different cohorts of wild-type C57BL/6J and CamKIIα-Cre male mice were treated with sub-chronic (7 days) AdipoRon, followed by behavioral, molecular, and electrophysiological experiments. (3) Results: 7-day AdipoRon treatment elicited antidepressant- and anxiolytic-like effects but did not affect hippocampal neurogenesis. AdipoRon treatment reduced hippocampal brain-derived neurotrophic factor (BDNF) levels, neuronal activation in the ventral dentate gyrus, and long-term potentiation of the perforant path. The knockdown of N-methyl-D-aspartate (NMDA) receptor subunits GluN2A and GluN2B in the ventral hippocampus did not affect the antidepressant- and anxiolytic-like effects of AdipoRon. (4) Conclusions: Increasing adiponectin signaling through sub-chronic AdipoRon treatment results in antidepressant- and anxiolytic-like effects independent of changes in hippocampal structural and synaptic function.

Natural Products for the Treatment of Post-stroke Depression

Post-stroke depression (PSD) is the most frequent and important neuropsychiatric consequence of stroke. It is strongly associated with exacerbated deterioration of functional recovery, physical and cognitive recoveries, and quality of life. However, its mechanism is remarkably complicated, including the neurotransmitters hypothesis (which consists of a monoaminergic hypothesis and glutamate-mediated excitotoxicity hypothesis), inflammation hypothesis, dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, and neurotrophic hypothesis and neuroplasticity. So far, the underlying pathogenesis of PSD has not been clearly defined yet. At present, selective serotonin reuptake inhibitors (SSRIs) have been used as the first-line drugs to treat patients with PSD. Additionally, more than SSRIs, a majority of the current antidepressants complied with multiple side effects, which limits their clinical application. Currently, a wide variety of studies revealed the therapeutic potential of natural products in the management of several diseases, especially PSD, with minor side effects. Accordingly, in our present review, we aim to summarize the therapeutic targets of these compounds and their potential role in-clinic therapy for patients with PSD.

Examining the Use of Antidepressants for Adolescents with Depression/Anxiety Who Regularly Use Cannabis: A Narrative Review

Depression and anxiety disorders are two of the most common and growing mental health concerns in adolescents. Consequently, antidepressant medication (AD) use has increased widely during the last decades. Several classes of antidepressants are used mainly to treat depression, anxiety, and obsessive-compulsive disorders by targeting relevant brain neurochemical pathways. Almost all randomized clinical trials of antidepressants examined patients with no concomitant medications or drugs. This does not address the expected course of therapy and outcome in cannabis users. Cannabis is the most commonly used illicit substance globally. Substantial changes in its regulation are recently taking place. Many countries and US states are becoming more permissive towards its medical and recreational use. The psychological and physiological effects of cannabis (mainly of its major components, tetrahydrocannabinol (THC) and cannabidiol (CBD)) have been extensively characterized. Cannabis use can be a risk factor for depressive and anxiety symptoms, but some constituents or mixtures may have antidepressant and/or anxiolytic potential. The aim of this literature review is to explore whether simultaneous use of AD and cannabis in adolescence can affect AD treatment outcomes. Based on the current literature, it is reasonable to assume that antidepressants are less effective for adolescents with depression/anxiety who frequently use cannabis. The mechanisms of action of antidepressants and cannabis point to several similarities and conjunctions that merit future investigation regarding the potential effectiveness of antidepressants among adolescents who consume cannabis regularly.

Novel Thiosemicarbazone Derivatives: In Vitro and In Silico Evaluation as Potential MAO-B Inhibitors

MAO-B inhibitors are frequently used in the treatment of neurodegenerative diseases such as Parkinson’s and Alzheimer’s. Due to the limited number of compounds available in this field, there is a need to develop new compounds. In the recent works, it was shown that various thiosemicarbazone derivatives show hMAO inhibitory activity in the range of micromolar concentration. It is thought that benzofuran and benzothiophene structures may mimic structures such as indane and indanone, which are frequently found in the structures of such inhibitors. Based on this view, new benzofuran/benzothiophene and thiosemicarbazone hybrid compounds were synthesized, characterized and screened for their hMAO-A and hMAO-B inhibitory activity by an in vitro fluorometric method. The compounds including methoxyethyl substituent (2b and 2h) were found to be the most effective agents in the series against MAO-B enzyme with the IC₅₀ value of 0.042 ± 0.002 µM and 0.056 ± 0.002 µM, respectively. The mechanism of hMAO-B inhibition of compounds 2b and 2h was investigated by Lineweaver–Burk graphics. Compounds 2b and 2h were reversible and non-competitive inhibitors with similar inhibition features as the substrates. The K_i values of compounds 2b and 2h were calculated as 0.035 µM and 0.046 µM, respectively, with the help of secondary plots. The docking study of compound 2b and 2h revealed that there is a strong interaction between the active sites of hMAO-B and analyzed compound.

The rapid anti-suicidal ideation effect of ketamine: A systematic review

In many countries suicide rates have been trending upwards for close to twenty years-presenting a public health crisis. Most suicide attempts and deaths are associated with psychiatric illness, usually a depressive disorder. Subanesthetic ketamine is the only FDA-approved antidepressant that works in hours not weeks-thus potentially transforming treatment of suicidal patients. We reviewed all randomized controlled trials of the effect of ketamine on suicidal ideation to determine if ketamine rapidly reduces suicidal ideation [SI] in depressed patients and how long the benefit persists after one dose and if the route of administration or dose affects the outcome. A systematic review was conducted as per PRISMA [preferred reporting items for systematic reviews and meta-analyses] criteria. PubMed search inclusive of "ketamine" and "suicide" yielded 358 results. Papers (N = 354) were then read by at least two authors, identifying 12 meeting eligibility requirements and eleven RCTs examining whether ketamine treatment ameliorated SI. Four of five RCTs examined racemic ketamine (0.5 mg/kg) given intravenously and found an advantage for ketamine over control for rapid reduction in SI in acutely depressed patients. Two studies examined intranasal esketamine in depressed suicidal patients and found no advantage over saline. One study examined outcome six weeks after a single intravenous dose of ketamine and found benefit for SI sustained relative to 24 h post-dose. Further research is warranted into: optimal dosing strategy, including number and frequency; and long-term efficacy and safety. Ultimately, it remains to be shown that ketamine's benefit for SI translates into prevention of suicidal behavior.

Is the Antidepressant Activity of Selective Serotonin Reuptake Inhibitors Mediated by Nicotinic Acetylcholine Receptors?

It is generally assumed that selective serotonin reuptake inhibitors (SSRIs) induce antidepressant activity by inhibiting serotonin (5-HT) reuptake transporters, thus elevating synaptic 5-HT levels and, finally, ameliorates depression symptoms. New evidence indicates that SSRIs may also modulate other neurotransmitter systems by inhibiting neuronal nicotinic acetylcholine receptors (nAChRs), which are recognized as important in mood regulation. There is a clear and strong association between major depression and smoking, where depressed patients smoke twice as much as the normal population. However, SSRIs are not efficient for smoking cessation therapy. In patients with major depressive disorder, there is a lower availability of functional nAChRs, although their amount is not altered, which is possibly caused by higher endogenous ACh levels, which consequently induce nAChR desensitization. Other neurotransmitter systems have also emerged as possible targets for SSRIs. Studies on dorsal raphe nucleus serotoninergic neurons support the concept that SSRI-induced nAChR inhibition decreases the glutamatergic hyperstimulation observed in stress conditions, which compensates the excessive 5-HT overflow in these neurons and, consequently, ameliorates depression symptoms. At the molecular level, SSRIs inhibit different nAChR subtypes by noncompetitive mechanisms, including ion channel blockade and induction of receptor desensitization, whereas α9α10 nAChRs, which are peripherally expressed and not directly involved in depression, are inhibited by competitive mechanisms. According to the functional and structural results, SSRIs bind within the nAChR ion channel at high-affinity sites that are spread out between serine and valine rings. In conclusion, SSRI-induced inhibition of a variety of nAChRs expressed in different neurotransmitter systems widens the complexity by which these antidepressants may act clinically.

Synthesis of Novel Pyrido[1,2-c]pyrimidine Derivatives with 6-Fluoro-3-(4-piperidynyl)-1,2-benzisoxazole Moiety as Potential SSRI and 5-HT1A Receptor Ligands

Two series of novel 4-aryl-2H-pyrido[1,2-c]pyrimidine (6a–i) and 4-aryl-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine (7a–i) derivatives were synthesized. The chemical structures of the new compounds were confirmed by ¹H and ¹³C NMR spectroscopy and ESI-HRMS spectrometry. The affinities of all compounds for the 5-HT_1A receptor and serotonin transporter protein (SERT) were determined by in vitro radioligand binding assays. The test compounds demonstrated very high binding affinities for the 5-HT_1A receptor of all derivatives in the series (6a–i and 7a–i) and generally low binding affinities for the SERT protein, with the exception of compounds 6a and 7g. Extended affinity tests for the receptors D₂, 5-HT_2A, 5-HT₆ and 5-HT₇ were conducted with regard to selected compounds (6a, 7g, 6d and 7i). All four compounds demonstrated very high affinities for the D₂ and 5-HT_2A receptors. Compounds 6a and 7g also had high affinities for 5-HT₇, while 6d and 7i held moderate affinities for this receptor. Compounds 6a and 7g were also tested in vivo to identify their functional activity profiles with regard to the 5-HT_1A receptor, with 6a demonstrating the activity profile of a presynaptic agonist. Metabolic stability tests were also conducted for 6a and 6d.

Vortioxetine as a new frontier in the treatment of chronic neuropathic pain: a review and update

Chronic neuropathic pain (CNP) is a disabling medical condition that impairs the health-related quality-of-life of affected patients. A high prevalence of anxiety, depression, sleep disturbance and cognitive impairment has frequently been reported in association with CNP, making the management of this disease complex and often multidisciplinary. Dual-acting agents such as selective serotonin and noradrenalin reuptake inhibitors (SNRIs) are considered particularly useful in the modulation of pain and in treatment of the mood disorders frequently associated with CNP. Recent evidence suggests that the top-down inhibitory control of pain involves the engagement and enhancement of descending endogenous opioidergic, cannabinoid and serotonergic systems, with the effect of serotonin being particularly related to the receptor subtypes that are preferentially activated; indeed serotonin induces analgesia via activation of 5-HT7 receptors and hyperalgesia via activation of 5-HT3 receptors. Vortioxetine (VO) is a novel multimodal serotonergic antidepressant with a unique mechanism of action. It has been demonstrated recently in experimental and clinical studies to have efficacy on pain hypersensitivity and on mood disorders. This drug inhibits the serotonin transporter with a high affinity, antagonises the 5-HT3, 5-HT1D and 5HT7 serotonin receptors, and activates the 5-HT1A and 5-HT1B receptors. In clinical studies, VO has proved effective at a dose of 10-20 mg/daily in short- and long-term treatment of patients with chronic orofacial pain, demonstrating a higher rate of clinical response and remission, a better acceptability, safety rate and tolerability, and a lower latency of action compared with other antidepressants. In the light of these recent findings, VO may be considered as a new pharmacological treatment also in relation to various types of CNP, particularly in elderly patients with concomitant mood disorders and cognitive impairment. The purpose of this review is to provide an up-to-date overview of the pharmacology and clinical applications of VO and to highlight its potential therapeutic properties and advantages in the management of CNP.

Vortioxetine versus other antidepressants in the treatment of burning mouth syndrome: An open-label randomized trial

OBJECTIVES

This randomized open-label trial compared the efficacy and tolerability of vortioxetine (15 mg/daily) with different antidepressants in the treatment of patients with burning mouth syndrome (BMS).

METHODS

One and hundred fifty BMS patients were randomized into five groups and treated with either vortioxetine, paroxetine (20 mg/daily), sertraline (50 mg/daily), escitalopram (10 mg/daily) or duloxetine (60 mg/daily). The Visual Analogue Scale (VAS), Total Pain Rating Index (T-PRI), Hamilton Rating Scales for Depression (HAM-D) and Anxiety (HAM-A), and Clinical Global Impression Improvement (CGI-I) and Efficacy scales (CGI-E) were performed at baseline and after 2, 4, 6, and 12 months of treatment. Any adverse events (AEs) were tabulated for each group. Descriptive statistics, including the Kruskal-Wallis non-parametric test and the Friedman non-parametric test for median comparisons between different times, were used.

RESULTS

All the antidepressants (AD) were associated with a significant decrease in the VAS, T-PRI, HAM-A, HAM-D, CGI-I, and CGI-E scores in the long-term (p < .001). However, the response rate of the vortioxetine group showed a significant reduction after six months. The medians, after 6 months, were as follows: VAS 0.0; T-PRI 2.0; HAM-A 7.0; HAM-D 7.0; CGI-I 1.0; and CGI-E 1.0 with a lower incidence of AEs (p < .019).

CONCLUSION

Vortioxetine was efficacious with a shorter latency of action and fewer AEs compared with other ADs.

Design, synthesis, molecular modelling and in vitro screening of monoamine oxidase inhibitory activities of novel quinazolyl hydrazine derivatives

A new series of N'-substituted benzylidene-2-(4-oxo-2-phenyl-1,4-dihydroquinazolin-3(2H)-yl)acetohydrazide (5a-5h) has been synthesized, characterized by FT-IR, NMR spectroscopy and mass spectrometry and tested against human monoamine oxidase (MAO) A and B. Only (4-hydroxy-3-methoxybenzylidene) substituted compounds gave submicromolar inhibition of MAO-A and MAO-B. Changing the phenyl substituent to methyl on the unsaturated quinazoline ring (12a-12d) decreased inhibition, but a less flexible linker (14a-14d) resulted in selective micromolar inhibition of hMAO-B providing insight for ongoing design.

Recent Studies on Anti-Depressant Bioactive Substances in Selected Species from the Genera Hemerocallis and Gladiolus: A Systematic Review

Herbal therapy is a potential alternative applied to pharmacological alleviation of depression symptoms and treatment of this disorder, which is predicted by the World Health Organization (WHO) to be the most serious health problem worldwide over the next several years. It has been well documented that many herbs with psychotropic effects have far fewer side effects than a variety of pharmaceutical agents used by psychiatrists for the treatment of depression. This systematic review presents literature data on the antidepressant activity of representatives of the genera Hemerocallis (H. fulva and H. citrina Baroni, family Xanthorrhoeaceae) and Gladiolus (G. dalenii, family Iridaceae) and on biologically active compounds and their mechanisms of action to consider the application of herbal preparations supporting the treatment of depression.

Classical psychedelics for the treatment of depression and anxiety: A systematic review

BACKGROUND

Depression and anxiety are prevalent psychiatric disorders that carry significant morbidity. Pharmacological and psychosocial interventions are used to manage these conditions, but their efficacy is limited. Recent interest into the use of psychedelic-assisted therapy using ayahuasca, psilocybin or lysergic acid diethylamide (LSD) may be a promising alternative for patients unresponsive to traditional treatments. This review aims to determine the efficacy and tolerability of psychedelics in the management of resistant depression.

METHODS

Clinical trials investigating psychedelics in patients with depression and/or anxiety were searched via MEDLINE, EMBASE and PsychINFO. Efficacy was assessed by measuring symptom improvement from baseline, and tolerability was evaluated by noting the incidence and type of adverse effects reported. Risk of bias was assessed.

RESULTS

Seven studies, with 130 patients, were analysed in this review. Three were conducted in patients with depression, two in patients with anxiety and two in patients with both. In a supportive setting, ayahuasca, psilocybin, and LSD consistently produced immediate and significant anti-depressant and anxiolytic effects that were endured for several months. Psychedelics were well-tolerated. The most common adverse effects were transient anxiety, short-lived headaches, nausea and mild increases in heart rate and blood pressure.

LIMITATIONS

At present, the number of studies on this subject is very limited; and the number of participating patients within these is also limited as the treatment under investigations is a relatively novel concept.

CONCLUSIONS

Though further evidence is required, psychedelics appear to be effective in significantly reducing symptoms of depression and anxiety and are well-tolerated.

In vivo long-lasting alterations of central serotonin transporter activity and associated dopamine synthesis after acute repeated administration of methamphetamine

Background

Methamphetamine (METH)-associated alterations in the striatal dopamine (DA) system or dopamine transport (DAT) have been identified in clinical and preclinical studies with positron emission tomography (PET) imaging but have not been well correlated with in vivo serotonin transporter (SERT) availability due to the lack of appropriate imaging agents to assess SERTs. N,N-dimethyl-2-(2-amino-4-[¹⁸F]-fluorophenylthio) benzylamine (4-[¹⁸F]-ADAM) has been developed by our group and validated for its high affinity and selectivity for SERTs, allowing the in vivo examination of SERT density, location, and binding function. The aims of this study were to investigate the potential of SERT imaging using 4-[¹⁸F]-ADAM PET to estimate the long-lasting effects of METH-induced serotonergic neurotoxicity, and further determine whether a correlative relationship exists between SERT availability/activity and tyrosine hydroxylase (TH) activity in various brain regions due to the long-lasting consequences of METH treatment.

Results

Male rats received four administrations of METH (5 or 10 mg/kg, s.c.) or saline (1 ml/kg, s.c.) at 1-h intervals. At 30 days post-administration, in vivo SERT availability and activity were measured by 4-[¹⁸F]ADAM PET imaging. In contrast to the controls, the uptake of 4-[¹⁸F]ADAM in METH-treated mice was significantly reduced in a dose-dependent manner in the midbrain, followed by the hypothalamus, thalamus, striatum, hippocampus, and frontal cortex. The regional effects of METH on TH activity were assessed by quantitative immunohistochemistry and presented as integrated optical density (IOD). A significant decrease in TH immunostaining and IOD ratios was seen in the caudate, putamen, nucleus accumbens, substantia nigra pars compacta, and substantia nigra pars reticulata in the METH-treated rats compared to controls.

Conclusion

The present results suggested that the long-lasting response to METH decreased the uptake of 4-[¹⁸F]-ADAM and varied regionally along with TH immunoreactivity. In addition, 4-[¹⁸F]ADAM PET could be used to detect serotonergic neuron loss and to evaluate the severity of serotonergic neurotoxicity of METH.

Molecular docking studies of coumarin hybrids as potential acetylcholinesterase, butyrylcholinesterase, monoamine oxidase A/B and β-amyloid inhibitors for Alzheimer's disease

Coumarins are the phytochemicals, which belong to the family of benzopyrone, that display interesting pharmacological properties. Several natural, synthetic and semisynthetic coumarin derivatives have been discovered in decades for their applicability as lead structures as drugs. Coumarin based conjugates have been described as potential AChE, BuChE, MAO and β-amyloid inhibitors. Therefore, the objective of this review is to focus on the construction of these pharmacologically important coumarin analogues with anti-Alzheimer’s activities, highlight their docking studies and structure–activity relationships based on their substitution pattern with respect to the selected positions on the chromen ring by emphasising on the research reports conducted in between year 1968 to 2017.

Clinical pharmacokinetics, pharmacodynamics, safety, and tolerability of JNJ-54175446, a brain permeable P2X7 antagonist, in a randomised single-ascending dose study in healthy participants

BACKGROUND

Central nervous system-derived interleukin-1β plays a role in mood disorders. P2X7 receptor activation by adenosine-triphosphate leads to the release of interleukin-1β.

AIMS

This first-in-human study evaluated safety, tolerability, pharmacokinetics and pharmacodynamics of a novel central nervous system-penetrant P2X7 receptor antagonist, JNJ-54175446, in healthy participants.

METHODS

The study had three parts: an ascending-dose study in fasted participants (0.5-300 mg JNJ-54175446); an ascending-dose study in fed participants (50-600 mg); and a cerebrospinal fluid study (300 mg). Target plasma concentrations were based on estimated plasma effective concentration (EC)₅₀ (105 ng/mL) and EC₉₀ (900 ng/mL) values for central nervous system P2X7 receptor binding.

RESULTS

Seventy-seven participants received a single oral dose of JNJ-54175446 ( n=59) or placebo ( n=18). Area under the curve of concentration time extrapolated to infinity (AUC_∞) increased dose-proportionally; maximum concentration (C_max) of plasma (C_max,plasma) increased less than dose-proportionally following single doses of JNJ-54175446. Because food increases bioavailability of JNJ-54175446, higher doses were given with food to evaluate safety at higher exposures. The highest C_max,plasma reached (600 mg, fed) was 1475±163 ng/mL. JNJ-54175446 C_max in cerebrospinal fluid, a proxy for brain penetration, was seven times lower than in total plasma; unbound C_max,plasma and C_max,CSF were comparable (88.3±35.7 vs 114±39 ng/mL). JNJ-54175446 inhibited lipopolysaccharide/3'-O-(4-benzoylbenzoyl)-ATP-induced interleukin-1β release from peripheral blood in a dose-dependent manner (inhibitory concentration (IC)₅₀:82 ng/mL; 95% confidence interval: 48-94). Thirty-three of 59 (55.9%) participants reported at least one treatment-emergent adverse event; the most common adverse event being headache (11/59, 18.6%).

CONCLUSION

Plasma exposure of JNJ-54175446 was dose-dependent. No serious adverse events occurred. Single-dose administration of JNJ-54175446>10 mg attenuated ex-vivo lipopolysaccharide-induced interleukin-1β release in peripheral blood. Passive brain penetration of JNJ-54175446 was confirmed.

Bilateral sciatic neuropathy with severe rhabdomyolysis following venlafaxine overdose: A case report

RATIONALE

Venlafaxine is an antidepressant and anxiolytic agent that functions by inhibiting central serotonin and norepinephrine reuptake, and it is a relatively recently introduced drug. In particular, overdose of venlafaxine has been reported to cause severe cardiac toxicity including ventricular tachycardia, prolongation of QT interval, and seizure or severe muscular injury. However, reports describing venlafaxine-induced rhabdomyolysis with neuropathy remain scarce. Accordingly, we report such a case involving a 49-year-old woman with bilateral sciatic neuropathy combined with rhabdomyolysis following venlafaxine overdose.

PATIENT CONCERNS

The patient complained of severe pain and tenderness in both thighs, weakness in both ankle flexor and extensor muscles, and a tingling sensation in the toes of both feet.

DIAGNOSES

Bilateral sciatic neuropathy combined with rhabdomyolysis following venlafaxine overdose.

INTERVENTION

Needle electromyography revealed fibrillation potentials and positive sharp waves, with absent recruitment in all the major muscles innervating the sciatic nerve bilaterally. Pelvic magnetic resonance imaging was performed after electromyography and revealed multifocal enhancement of signal intensity, suggesting muscle necrosis in the gluteus and thigh muscles, and swelling of both sciatic nerves on short tau inversion recovery (STIR) imaging sequences.

OUTCOMES

Two months later, the patient's ankle dorsiflexion strength, measured with manual muscle test, was grade 0/0, and ankle plantar flexion was grade 0/0. The patient reported little sensation at the lateral and posterior aspects of her lower leg, and dorsum and sole of the foot. A follow-up electromyography study revealed improvement in the long head of the right biceps femoris; polyphasic motor unit action potentials with diminished recruitment were observed, but otherwise unchanged.

LESSONS

When encountering patients who have overdosed on venlafaxine, it is very important to detect and treat severe complications such as cardiac toxicity, seizure, and rhabdomyolysis, among others. However, if rhabdomyolysis has already materialized, it should not be forgotten that the secondary damage caused by it. Physicians should rapidly detect and be minimized to mitigate future complications.

Efficacy of antidepressants: bias in randomized clinical trials and related issues

INTRODUCTION

Countless antidepressant randomized trials were conducted and showed statistically significant benefits of selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) over placebo. Meanwhile, critics are increasing regarding the efficacy of antidepressants in the treatment of MDD because at least a proportion of clinical trials could be hampered by various biases. In contrast, number of failed trials is increasing in the recent years which have made developing psychiatric medications progressively more time-consuming and expensive. Areas covered: Biases and related issues in clinical trials for antidepressants can be identified as an important common contributing factor to the two paradoxical phenomenon. This review identifies possible biases that can occur before, during, and after clinical trials of antidepressant. Expert commentary: Recent studies not only may over-estimate efficacy of antidepressants, but also may exaggerate placebo response because of various biases. Sponsorship and publication biases have been one of the targets of the criticism and ethical debate. Thus, initiating new trend of research by re-organizing academic-industry partnership will be the most important task in the next five years.

Promoter IV-BDNF deficiency disturbs cholinergic gene expression of CHRNA5, CHRM2, and CHRM5: effects of drug and environmental treatments

Brain-derived neurotrophic factor (BDNF) promotes maturation of cholinergic neurons. However, how activity-dependent BDNF expression affects specific cholinergic gene expression remains unclear. This study addressed this question by determining mRNA levels of 22 acetylcholine receptor subunits, the choline transporter (CHT), and the choline acetyltransferase (ChAT) in mice deficient in activity-dependent BDNF via promoter IV (KIV) and control wild-type mice. Quantitative RT-PCR revealed significant reductions in nicotinic acetylcholine receptor alpha 5 (CHRNA5) in the frontal cortex and hippocampus and M5 muscarinic acetylcholine receptor (CHRM5) in the hippocampus, but significant increases in M2 muscarinic acetylcholine receptor (CHRM2) in the frontal cortex of KIV mice compared to wild-type mice. Three-week treatments with fluoxetine, phenelzine, duloxetine, imipramine, or an enriched environment treatment (EET) did not affect the altered expression of these genes except that EET increased CHRNA5 levels only in KIV frontal cortex. EET also increased levels of CHRNA7, CHT, and ChAT, again only in the KIV frontal cortex. The imipramine treatment was most prominent among the four antidepressants; it up-regulated hippocampal CHRM2 and frontal cortex CHRM5 in both genotypes, and frontal cortex CHRNA7 only in KIV mice. To the best of our knowledge, this is the first evidence that BDNF deficiency disturbs expression of CHRNA5, CHRM2, and CHRM5. Our results suggest that promoter IV-BDNF deficiency - which occurs under chronic stress - causes cholinergic dysfunctions via these receptors. EET is effective on CHRNA5, while its compensatory induction of other cholinergic genes or drugs targeting CHRNA5, CHRM2, and CHRM5 may become an alternative strategy to reverse these BDNF-linked cholinergic dysfunctions.

Patterns of use and toxicity of new para-halogenated substituted cathinones: 4-CMC (clephedrone), 4-CEC (4-chloroethcatinone) and 4-BMC (brephedrone)

OBJECTIVE

This paper aims to present results of the analysis of clephedrone (4-CMC), 4-chloroethcathinone (4-CEC), and brephedrone (4-BMC) on recreational drug markets and a systematic review of all the available information concerning these substances.

MATERIAL AND METHODS

Samples collected by the drug checking service of the Spanish harm reduction NGO-Energy Control were analyzed and systematic research was conducted. Between June 2014 and October 2016, 1,471 samples with at least one NPS were analyzed, 397 of which contained cathinones.

RESULTS

Clephedrone was found in 29 samples, brephedrone in 8, and both were present in 2 samples. 4-Chloroethcathinone was detected in 5 samples. Eleven out of the 47 purchased samples (23.4%) were tested to contain the substance the user expected. Samples received were mainly sold as 3-MMC, MDMA, ketamine, and other cathinones. No literature on the effects or toxicity of these substances was found; the only information available was on internet fora. On many posts, users exhibit concerns about potential toxicity and side effects of using these substances.

CONCLUSION

Since the emergence of these substances could prove to be the next step to the cat-and-mouse game existing between drug producers and legislation, further clinical and epidemiological research should be carried out in order to build evidence to support policy for public health issues.

Antidepressive and anxiolytic effects of ayahuasca: a systematic literature review of animal and human studies

OBJECTIVE

To conduct a systematic literature review of animal and human studies reporting anxiolytic or antidepressive effects of ayahuasca or some of its isolated alkaloids (dimethyltryptamine, harmine, tetrahydroharmine, and harmaline).

METHODS

Papers published until 3 April 2015 were retrieved from the PubMed, LILACS and SciELO databases following a comprehensive search strategy and using a predetermined set of criteria for article selection.

RESULTS

Five hundred and fourteen studies were identified, of which 21 met the established criteria. Studies in animals have shown anxiolytic and antidepressive effects of ayahuasca, harmine, and harmaline, and experimental studies in humans and mental health assessments of experienced ayahuasca consumers also suggest that ayahuasca is associated with reductions in anxiety and depressive symptoms. A pilot study reported rapid antidepressive effects of a single ayahuasca dose in six patients with recurrent depression.

CONCLUSION

Considering the need for new drugs that produce fewer adverse effects and are more effective in reducing anxiety and depression symptomatology, the described effects of ayahuasca and its alkaloids should be further investigated.

Synthesis and evaluation of small molecules bearing a benzyloxy substituent as novel and potent monoamine oxidase inhibitors

A new series of small molecules bearing a benzyloxy substituent have been designed, synthesized and evaluated for hMAO inhibitory activity in vitro. Most of the compounds were potent and selective MAO-B inhibitors, and were weak inhibitors of MAO-A. In particular, compounds 9e (IC₅₀ = 0.35 μM) and 10e (IC₅₀ = 0.19 μM) were the most potent MAO-B inhibitors, and exhibited the highest selectivity for MAO-B (9e, SI > 285.7-fold and 10e, SI = 146.8-fold). In addition, the structure-activity relationships for MAO-B inhibition indicated that electron-withdrawing groups in the open small molecules were more suitable for MAO-B inhibition, and substitutions at the benzyloxy of the open small molecules, particularly with the halogen substituted benzyloxy, were more favorable for MAO-B inhibition. Molecular docking studies have been done to explain the potent MAO-B inhibition of the open small molecules. Furthermore, the representative compounds 9e and 10e showed low neurotoxicity in SH-SY5Y cells in vitro. So the small molecules bearing the benzyloxy substituent could be used to develop promising drug candidates for the therapy of neurodegenerative diseases.

Potentials of Mangifera indica in the treatment of depressive-anxiety disorders: possible mechanisms of action

BACKGROUND

Mangifera indica (Anacardiaceae) is an important herb in the traditional African and Ayurvedic medicines. The stem barks are used in the treatment of hypertension, insomnia, tumour, depression, rheumatism and as a tonic. This study was carried out to investigate antidepressant- and anxiolytic-like effect of the hydroethanol stem bark extract of M. indica (HeMI) in mice.

METHODS

HeMI (12.5-100 mg/kg, p.o.) was administered 1 h before subjecting the animal to the forced swim test (FST), tail suspension test (TST) and elevated plus maze tests (EPM).

RESULTS

HeMI (12.5-100 mg/kg, p.o.) treatment produced significant reduction in immobility time [F(6.56)=8.35, p<0.001], [F(6,56)=7.55, p<0.001] in the FST and TST, respectively. Moreover, co-administration of sub-therapeutic doses of imipramine or fluoxetine with HeMI (3.125 mg/kg) elicited significant reduction in time spent immobile in the FST. However, pretreatment of mice with parachlorophenylalanine, metergoline, yohimbine or sulpiride abolished the antidepressant-like effect elicited by HeMI. In the EPM, HeMI produced significant [F(5,42)=8.91, p<0.001] increase in open arms exploration by 75.55 % and this effect was blocked by pretreatment of mice with flumazenil or metergoline.

CONCLUSIONS

Findings from this study showed antidepressant-like effect of M. indica through interaction with 5-HT2 receptor, α2-adrenoceptor and dopamine D2-receptors. Also, an anxiolytic-like effect through its affinity for 5-HT2 and benzodiazepine receptors. Hence, M. indica could be a potential phytotherapeutic agent in the treatment of mixed anxiety-depressive illness.

Yokukansan improves behavioral and psychological symptoms of dementia by suppressing dopaminergic function

Although three drugs, risperidone, yokukansan, and fluvoxamine, have shown equal efficacy in treating behavioral and psychological symptoms of dementia (BPSD) in our previous study, their mechanisms of action are different from one another. Monoamines have attracted attention for their key roles in mediating several behavioral symptoms or psychological symptoms through synaptic signaling. We aimed to clarify the monoamines changed by treatment with each drug in patients with BPSD. The main purpose of this study was to determine whether plasma levels of catecholamine metabolites are correlated with pharmacological treatments. This was an 8-week, rater-blinded, randomized, flexible-dose, triple-group trial. In total, 90 subjects were recruited and subsequently three different drugs were allocated to 82 inpatients with BPSD. We examined BPSD data from patients who completed 8 weeks of treatment. Eventually, we analyzed 42 patients (yokukansan: 17; risperidone: 9; fluvoxamine: 16). Homovanillic acid, a metabolite of dopamine, and 3-methoxy-4-hydroxyphenylglycol, a metabolite of noradrenaline, in their plasma were analyzed by high-performance liquid chromatography with electrochemical detection. All three drugs showed equal significant efficacy between baseline and study endpoint. By contrast, biomarkers showed mutually different changes. Patients in the yokukansan group had significantly decreased plasma homovanillic acid levels from baseline. Conversely, patients in the risperidone and fluvoxamine groups exhibited no significant changes in plasma homovanillic acid levels from baseline. Yokukansan contains geissoschizine methyl ether, which is known to have a partial agonist effect on dopamine D2 receptors. An improvement in BPSD condition with the intake of yokukansan is suggested to occur through a suppressed dopaminergic function, which is similar to the effect of aripiprazole.

Novel 4-aryl-pyrido[1,2-c]pyrimidines with dual SSRI and 5-HT(1A) activity. Part 5

A series of novel 4-aryl-pyrido[1,2-c]pyrimidine derivatives containing a 1-(2-quinoline)piperazine moiety was synthesized. The chemical structure of new compounds was confirmed by FT-IR, (1)H NMR, (13)C NMR and HRMS spectra as well as elemental analysis. Affinity of the novel pyrido[1,2-c]pyrimidine derivatives for 5-HT1A, 5-HT2A receptors and serotonin transporter (SERT) was evaluated in an in vitro radioligand binding assay. Tested compounds showed moderate to high affinity for 5-HT1AR and SERT and low affinity for 5-HT2AR. Selected ligands were subjected to in vivo tests, such as induced hypothermia and the forced swimming test in mice, which determined presynaptic agonistic activity of the ligands 8d, 8e, 9d and 9e and presynaptic antagonistic activity of the ligands 8a, 8b, 9a, 9b. Additionally, metabolic stability evaluation was performed for selected ligands, proving that a para-substitution in the 4-aryl-pyrido[1,2-c]pyrimidine moiety leads to an increase in stability, whereas a substitution in the ortho-position lowers the stability.

In vitro and in vivo regulation of synaptogenesis by the novel antidepressant spadin

BACKGROUND AND PURPOSE

We have described a novel antidepressant peptide, spadin, that acts by blocking the TWIK-related-potassium channel, type 1 (TREK-1). Here, we examined possible mechanisms of action of spadin at both molecular and cellular levels.

EXPERIMENTAL APPROACHES

Effects of spadin were measured in primary cultures of neurons or tissues from mice injected i.v. with spadin. Western blots, qPCR, histochemical and electrophysiological techniques were used.

KEY RESULTS

In vitro, spadin increased neuronal membrane potential and activated both the MAPK and PI3K signalling pathways, in a time- and concentration-dependent manner. The latter pathway was involved in the protective effect of spadin against staurosporine-induced apoptosis. Also, spadin enhanced both mRNA expression and protein of two markers of synaptogenesis, the post-synaptic density protein of 95 kDalton (PSD-95) and synapsin. We confirmed these effects on synaptogenesis by the observation that spadin treatment significantly increased the proportion of mature spines in cortical neurons. Finally, in vivo injections of spadin led to a rapid increase in both mRNA expression and protein level of brain-derived neurotrophic factor (BDNF) in the hippocampus, confirming the antidepressant action of the peptide. We argue for a new role of spadin in synaptogenesis as both PSD-95 and synapsin mRNA expression and protein levels were further enhanced in the hippocampus, following treatment in vivo with the peptide.

CONCLUSIONS AND IMPLICATIONS

These findings provide new mechanisms of action for the rapidly acting antidepressant peptide spadin by stimulating expression of BDNF and synaptic proteins, both in vitro and in vivo.

Ketamine and other potential glutamate antidepressants

The need for rapid acting antidepressants is widely recognised. There has been much interest in glutamate mechanisms in major depressive disorder (MDD) as a promising target for the development of new antidepressants. A single intravenous infusion of ketamine, a N-methyl-d-aspartate (NMDA) receptor antagonist anaesthetic agent, can alleviate depressive symptoms in patients within hours of administration. The mechanism of action appears to be in part through glutamate release onto non-NMDA receptors including α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and metabotropic receptors. However these are also reported effects on 5-HT, dopamine and intracellular effects on the mammalian target of rapamycin (mTOR) pathway. The effects of SSRI (Selective Serotonin Reuptake Inhibitor) antidepressants may also involve alterations in NMDA function. The article reviews the effect of current antidepressants on NMDA and examines the efficacy and mechanism of ketamine. Response to ketamine is also discussed and comparison with other glutamate drugs including lamotrigine, amantadine, riluzole, memantine, traxoprodil, GLYX-13, MK-0657, RO4917523, AZD2066 and Coluracetam. Future studies need to link the rapid antidepressant effects seen with ketamine to inflammatory theories in MDD.

Synthesis and evaluation of 6-methylcoumarin derivatives as potent and selective monoamine oxidase B inhibitors

Compound 5n was a potent and selective inhibitor of hMAO-B.

Antidepressant-like effects of the phosphodiesterase-4 inhibitor etazolate and phosphodiesterase-5 inhibitor sildenafil via cyclic AMP or cyclic GMP signaling in mice

Inhibition of phosphodiesterase-4 or 5 (PDE4 or PDE5) increases cyclic adenosine monophosphate (cAMP)- or cyclic guanosine monophosphate (cGMP), respectively, which activates cAMP response element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF)/neuropeptide VGF (non-acryonimic) signaling and produces antidepressant-like effects on behavior. However, causal links among these actions have not been established. In the present study, mice were evaluated for the effects of etazolate and sildenafil, the inhibitor of PDE4 or PDE5, respectively, on depressive-like behavior induced by chronic unpredictable mild stress (CUMS) in the forced-swimming test (FST) and tail suspension test (TST), in the presence or absence of the inhibitor of protein kinase A (PKA) or protein kinase G (PKG) via intracerebroventricular (i.c.v.) infusions. The levels of cAMP, cGMP and expression of pCREB, CREB, BDNF and VGF in both the hippocampus and prefrontal cortex were determined. The results showed that etazolate at 5.0 mg/kg or sildenafil at 30 mg/kg significantly reversed CUMS-induced depressive-like behavior; the effects were paralleled with the increased levels of cAMP/pCREB/BDNF/VGF or cGMP/pCREB/BDNF/VGF signaling, respectively. These effects were completely abolished following inhibition of PKA or PKG, respectively. The results suggest that inhibition of PDE4 by etazolate or PDE5 by sildenafil produced antidepressant-like effects in CUMS-treated animals via cAMP or cGMP signaling, which shares the common downstream signal pathway of CREB/BDNF/VGF.

Emerging treatments for major depression

Antidepressant drugs were introduced into clinical practice in the mid-20th Century. While for the most part they have proven effective for the amelioration of depressive symptoms, they are associated with significant deficiencies. These well-recognized shortcomings have given impetus to the pursuit of new molecules that seek to improve on the efficacy, tolerability and safety of existing medications. The following article reviews several new compounds that may have antidepressant potential. Some are more advanced in development, having undergone clinical trials, whereas the clinical potential of others is yet to be explored. For this latter group of compounds, the antidepressant potential relies on their activity in validated animal models. Agomelatine and duloxetine are in the first category, having shown antidepressant efficacy in clinical trials. The blockade of cortisol secretion continues to be a focus of attention for the development of new antidepressants. Thus, synthesis inhibitors, nonpeptide antagonists of corticotropin-releasing factor and glucocorticoid receptor antagonists show some promise in clinical and preclinical tests. Antagonists of the neuropeptide substance P, vasopressin and neuropeptide Y represent a departure of approach from traditional monoamine receptor-based mechanisms. While the clinical results with one substance P antagonist have led to the cessation of further trials, other molecules are in development. Approaches to treatment based on glutamatergic transmission arose from observations in animal models. The clinical evaluation of such compounds awaits further development. The extent to which new agents can be judged to have met the goals of efficacy, tolerability and safety rely not only acute treatment trials but also on longer-term outcomes and postmarketing surveillance. Whether any of the new agents canvassed here prove to be significantly better than existing agents is clearly a judgement for the future.

Novel mannich bases, 5-arylimidazolidine-2,4-dione derivatives with dual 5-HT(1A) receptor and serotonin transporter affinity

A computer aided ligand design study of imidazolidine-2,4-dione derivatives was conducted in order to obtain compounds with dual 5-HT(1A) receptor and serotonin transporter (SERT) affinity. According to molecular modeling results, series of Mannich bases were chosen and synthesized. Investigated compounds were tested for 5-HT(1A) , 5-HT(2A) , α(1) and SERT affinity. Two selected compounds (5, 9) were characterized in functional experiments and possessed a pharmacological profile which may enhance SERT blocking efficacy - 5-HT(1A) partial agonism and 5-HT(2A) antagonism in one molecule. Furthermore these compounds displayed satisfactory selectivity over adrenergic α(1) receptors. The most promising compounds, 5-arylimidazolidine-2,4-dione derivatives with 4-(3-chlorophenyl)piperazinylmethyl moiety were tested for antidepressant and anxiolytic activity. In particular, compound 5 (5-(2-methoxyphenyl)-3-{1-[4-(3-chlorophenyl)piperazin-1-yl]methyl}-imidazolidine-2,4-dione), tested in the forced swim test in mice, exhibited a favorable antidepressant-like profile without affecting spontaneous locomotor activity.

PET imaging of the brain serotonin transporters (SERT) with N,N-dimethyl-2-(2-amino-4-[18F]fluorophenylthio)benzylamine (4-[18F]-ADAM) in humans: a preliminary study

PURPOSE

The aim of this study was to assess the feasibility of using 4-[(18)F]-ADAM as a brain SERT imaging agent in humans.

METHODS

Enrolled in the study were 19 healthy Taiwanese subjects (11 men, 8 women; age 33 ± 9 years). The PET data were semiquantitatively analyzed and expressed as specific uptake ratios (SUR) and distribution volume ratios (DVR) using the software package PMOD. The SUR and DVR of 4-[(18)F]-ADAM in the raphe nucleus (RN), midbrain (MB), thalamus (TH), striatum (STR) and prefrontal cortex (PFC) were determined using the cerebellum (CB) as the reference region.

RESULTS

4-[(18)F]-ADAM bound to known SERT-rich regions in human brain. The order of the regional brain uptake was MB (RN) > TH > STR > PFC > CB. The DVR (n = 4, t* = 60 min) in the RN, TH, STR and PFC were 3.00 ± 0.50, 2.25 ± 0.45, 2.05 ± 0.31 and 1.40 ± 0.13, respectively. The optimal time for imaging brain SERT with 4-[(18)F]-ADAM was 120-140 min after injection. At the optimal imaging time, the SURs (n = 15) in the MB, TH, STR, and PFC were 2.25 ± 0.20, 2.28 ± 0.20, 2.12 ± 0.18 and 1.47 ± 0.14, respectively. There were no significant differences in SERT availability between men and women (p < 0.05).

CONCLUSION

The results of this study showed that 4-[(18)F]-ADAM was safe for human studies and its distribution in human brain appeared to correlate well with the known distribution of SERT in the human brain. In addition, it had high specific binding and a reasonable optimal time for imaging brain SERT in humans. Thus, 4-[(18)F]-ADAM may be feasible for assessing the status of brain SERT in humans.

Influence of sildenafil on the antidepressant activity of bupropion and venlafaxine in the forced swim test in mice

Recent studies highlight the involvement of the nitrergic system in the mechanism of action of antidepressant drugs. Sildenafil, a selective PDE5 inhibitor, was shown to abolish the anti-immobility effects of bupropion, venlafaxine and s-citalopram in mice. In this study we assessed the effects of sildenafil on the activity of bupropion and venlafaxine in the forced swim test in mice. Swim trials were conducted by placing mice in glass cylinders filled with water for 6min and the duration of the behavioral immobility during the last 4min of the test was evaluated. Locomotor activity was evaluated with photoresistor actimeters. Brain and serum concentrations of the studied antidepressants were determined by HPLC method. Sildenafil at a dose of 20mg/kg, but not 5 and 10mg/kg, significantly increased the anti-immobility action of bupropion (20mg/kg). The antidepressant activity of venlafaxine (2mg/kg) was potentiated by joint administration with sildenafil at doses of 10 and 20mg/kg. Since the combined treatments did not increase the locomotor activity, the antidepressant-like effects were not related to non-specific behavioral activation. Data from pharmacokinetic studies revealed that sildenafil increased bupropion and venlafaxine levels in serum without affecting their concentrations in the brain. The present study demonstrates the enhancement of anti-immobility action of bupropion and venlafaxine by sildenafil co-administration. The observed changes might have been partly due to pharmacokinetic interactions. However, mechanisms underlying the effects of sildenafil on the antidepressant activity of bupropion and venlafaxine should be carefully evaluated in further studies.