Agomelatine for depression: expanding the horizons?

Agomelatine bears promising potential in treating bipolar depression- a systematic review

INTRODUCTION

The controversy of antidepressant use in bipolar depression remains controversial. Agomelatine (AGO) is an effective antidepressant in major depressive disorder (MDD), but its application in bipolar depression was little discussed. We aimed to provide a comprehensive systematic review of clinical evidence from studies examining the efficacy and safety of AGO for bipolar depression.

METHODS

We conducted a systematic review about AGO trials for the treatment of bipolar patients. We searched PubMed, MEDLINE, Embase, and Cochrane for relevant studies published since each database's inception. We synthesised evidence regarding efficacy (mood and rhythm) and tolerability across studies.

RESULTS

We identified 6 studies including 272 participants (44% female). All studies used 25-50 mg AGO per day for treatment combined or not combined with mood stabilisers (MS). Across all 6 studies, there were improvements in depression evaluated by depression rating scores and response rate over time. The response rates varied from 43% to 91% within 6-12 weeks. Although AGO was found of better efficacy in bipolar depression compared to recurrent depression, its efficacy remains controversial. Most studies have shown AGO to be effective after just about a week. AGO was reasonably well tolerated both in acute and extension period, without obvious risk in inducing mood switching.

CONCLUSION

AGO is promising in treating bipolar depression with significant efficacy and well tolerability. However, more strictly designed and large-sample trials are needed in further research with homogeneity within intervention and treatment groups.

Ginsenoside Rg1: A Neuroprotective Natural Dammarane-Type Triterpenoid Saponin With Anti-Depressive Properties

BACKGROUND

Depression, a widespread mental disorder, presents significant risks to both physical and mental health due to its high rates of recurrence and suicide. Currently, single-target antidepressants typically alleviate depressive symptoms or delay the progression of depression rather than cure it. Ginsenoside Rg1 is one of the main ginsenosides found in Panax ginseng roots. It improves depressive symptoms through various mechanisms, suggesting its potential as a treatment for depression.

MATERIALS AND METHODS

We evaluated preclinical studies to comprehensively discuss the antidepressant mechanism of ginsenoside Rg1 and review its toxicity and medicinal value. Additionally, pharmacological network and molecular docking analyses were performed to further validate the antidepressant effects of ginsenoside Rg1.

RESULTS

The antidepressant mechanism of ginsenoside Rg1 may involve various pharmacological mechanisms and pathways, such as inhibiting neuroinflammation and over-activation of microglia, preserving nerve synapse structure, promoting neurogenesis, regulating monoamine neurotransmitter levels, inhibiting hyperfunction of the hypothalamic-pituitary-adrenal axis, and combatting antioxidative stress. Moreover, ginsenoside Rg1 preserves astrocyte gap junction function by regulating connexin43 protein biosynthesis and degradation, contributing to its antidepressant effect. Pharmacological network and molecular docking studies identified five targets (AKT1, STAT3, EGFR, PPARG, and HSP90AA1) as potential molecular regulatory sites of ginsenoside Rg1.

CONCLUSIONS

Ginsenoside Rg1 may exert its antidepressant effects via various pharmacological mechanisms. In addition, multicenter clinical case-control and molecular targeted studies are required to confirm both the clinical efficacy of ginsenoside Rg1 and its potential direct targets.

Agomelatine promotes differentiation of oligodendrocyte precursor cells and preserves white matter integrity after cerebral ischemic stroke

White matter injury contributes to neurological disorders after acute ischemic stroke (AIS). The repair of white matter injury is dependent on the re-myelination by oligodendrocytes. Both melatonin and serotonin antagonist have been proved to protect against post-stroke white matter injury. Agomelatine (AGM) is a multi-functional treatment which is both a melatonin receptor agonist and selective serotonin receptor antagonist. Whether AGM protects against white matter injury after stroke and the underlying mechanisms remain elusive. Here, using the transient middle cerebral artery occlusion (tMCAO) model, we evaluated the therapeutic effects of AGM in stroke mice. Sensorimotor and cognitive functions, white matter integrity, oligodendroglial regeneration and re-myelination in stroke hemisphere after AGM treatment were analyzed. We found that AGM efficiently preserved white matter integrity, reduced brain tissue loss, attenuated long-term sensorimotor and cognitive deficits in tMCAO models. AGM treatment promoted OPC differentiation and enhanced re-myelination both in vitro, ex vivo and in vivo, although OPC proliferation was unaffected. Mechanistically, AGM activated low density lipoprotein receptor related protein 1 (LRP1), peroxisome proliferator-activated receptor γ (PPARγ) signaling thus promoted OPC differentiation and re-myelination after stroke. Inhibition of PPARγ or knock-down of LRP1 in OPCs reversed the beneficial effects of AGM. Altogether, our data indicate that AGM represents a novel therapy against white matter injury after cerebral ischemia.

Repurposed drug agomelatine is therapeutic against collagen-induced arthritis via iNOS targeting

BACKGROUND

The most promising biologics tumor necrosis factor α (TNFα) inhibitors are effective in treating rheumatoid arthritis (RA) in only 50-70 % of the cases; thus, new drugs targeting TNFα-mediated inflammation are required.

METHODS

Firstly, the drugs that could inhibit FLS proliferation and TNFα induced inflammatory cytokine production were screened. Secondly, treatment effects of the identified drugs were screened in collagen-induced arthritis (CIA) mouse model. Thirdly, the inhibitory effect of the identified drug, agomelatine (AOM), on TNFα induced inflammatory cytokine production and NF-κB activity were confirmed. Fourthly, bioinformatics was applied to predict the binding target of AOM and the binding was confirmed, and the already known inhibitor of target was used to test the treatment effect for CIA mouse model. Finally, the effect of AOM on signaling pathway was tested and on TNFα induced inflammatory cytokine production was observed after inhibiting the target.

RESULTS

AOM effectively inhibited TNFα-induced NF-κB activation, NF-κB p65 translocation, and inflammatory cytokines production in vitro and was therapeutic against CIA. The mechanistic study indicated inducible nitric oxide synthase (iNOS) as the binding target of AOM. 1400 W, a known inhibitor of iNOS, could effectively treat CIA by decreasing iNOS activity and the levels of inflammatory cytokines. The inhibitory effect of AOM on TNFα-induced inflammation was further elucidated by 1400 W, or NF-κB p65 inhibitor JSH-23, indicating that AOM is therapeutic against CIA via iNOS/ERK/p65 signaling pathway after binding with iNOS.

CONCLUSIONS

AOM is therapeutic against CIA via inhibition of the iNOS/ERK/p65 signaling pathway after binding with iNOS.

Neural plasticity and depression treatment

Depression is one of the most common mental disorders, which can lead to a variety of emotional problems and even suicide at its worst. As this neuropsychiatric disorder causes the patients to suffer a lot and function poorly in everyday life, it is imposing a heavy burden on the affected families and the whole society. Several hypotheses have been proposed to elucidate the pathogenesis of depression, such as the genetic mutations, the monoamine hypothesis, the hypothalamic-pituitary-adrenal (HPA) axis hyperactivation, the inflammation and the neural plasticity changes. Among these models, neural plasticity can occur at multiple levels from brain regions, cells to synapses structurally and functionally during development and in adulthood. In this review, we summarize the recent progresses (especially in the last five years) on the neural plasticity changes in depression under different organizational levels and elaborate different treatments for depression by changing the neural plasticity. We hope that this review would shed light on the etiological studies for depression and on the development of novel treatments.

Pharmacological management of neuropsychiatric symptoms in geriatric traumatic brain injury: a scoping review

OBJECTIVE

This scoping review aimed to summarize the existing knowledge base on the pharmacological management of neuropsychiatric symptoms in geriatric TBI and identify gaps in the literature to guide future research.

METHODS

Seven electronic databases and nine gray literature databases were systematically searched for articles that examined pharmacological management of neuropsychiatric symptoms in adults aged 65 years and over with TBI. The search was guided by four main concepts and selected based on inclusion criteria. Unpublished studies and abstract-only articles were excluded.

RESULTS

Eight studies met full inclusion criteria. Patterns of psychotropic medication prescription and prescribing principles for geriatric TBI were elucidated. There were no clear or consistent prescribing guidance. Therefore, prescribing recommendations could not be addressed. Current management is inferred from research primarily done in younger adults, or extrapolated from the literature and practice of treating other psychiatric and neurological disorders.

CONCLUSION

There are significant gaps in knowledge and no evidence-based guidelines for the treatment of neuropsychiatric symptoms in geriatric TBI. TBI among older adults is distinct from those of younger adults and thereby demands a unique approach to treatment and research. The authors' proposed guideline is an important first step in facilitating guideline development and future research.

Agomelatine improves streptozotocin-induced diabetic nephropathy through melatonin receptors/SIRT1 signaling pathway

INTRODUCTION

Diabetic nephropathy (DN) is a major cause of end-stage renal disease (ESRD). Agomelatine, a melatonin receptor agonist, has a potent anti-inflammatory activity. The current study aimed to determine the ameliorative anti-inflammatory effect of agomelatine against DN.

METHODS

We used 10 % fructose with streptozotocin (STZ) to induce DN in male Wistar rats. Diabetic rats were treated with agomelatine in presence or absence of melatonin receptor antagonist (luzindole) or Sirtuin1 (SIRT1) inhibitor (EX527). SIRT1 expression was measured by qRT-PCR and immunohistochemical analysis. The expression of nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB), 5'adenosine monophosphate-activated protein kinase (AMPK), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion protein-1 (VCAM-1), and monocyte chemoattractant protein-1 (MCP-1) were measured using ELISA. Histological assessment was performed using hematoxylin and eosin-stained renal sections.

RESULTS

Fructose and STZ treatment induced diabetes, insulin resistance, and renal damage accompanied by reduced SIRT1 expression, increased NFκB activation, and decreased AMPK phosphorylation in the kidney. Agomelatine treatment improved kidney histology and function and upregulated SIRT1 expression (2-fold). Inhibition of melatonin receptors and SIRT1 activity increased NFκB phosphorylation (2.13 and 1.98-folds, respectively), reduced AMPK activation (0.51 and 0.53-folds, respectively), increased inflammatory markers ICAM-1 (2.16 and 2.23-folds, respectively), VCAM-1 (2.19 and 2.26-folds, respectively), and MCP-1(2.84 and 3.12-folds, respectively), and inhibited the ameliorative effect of agomelatine on kidney structure and function.

CONCLUSION

Our findings reveal the ameliorative anti-inflammatory activity of agomelatine against STZ-induced DN and this effect is SIRT1- and melatonin receptor-dependent. Therefore, agomelatine may be beneficial to prevent the development of ESRD from diabetes mellitus.

The Role of Inflammation in the Pathophysiology of Depression and Suicidal Behavior: Implications for Treatment

Depression and suicidal behavior are 2 complex psychiatric conditions of significant public health concerns due to their debilitating nature. The need to enhance contemporary treatments and preventative approaches for these illnesses not only calls for distillation of current views on their pathogenesis but also provides an impetus for further elucidation of their novel etiological determinants. In this regard, inflammation has recently been recognized as a potentially important contributor to the development of depression and suicidal behavior. This review highlights key evidence that supports the presence of dysregulated neurometabolic and immunologic signaling and abnormal interaction with microbial species as putative etiological hallmarks of inflammation in depression as well as their contribution to the development of suicidal behavior. Furthermore, therapeutic insights addressing candidate mechanisms of pathological inflammation in these disorders are proposed.

Agomelatine in the treatment of anhedonia, somatic symptoms, and sexual dysfunction in major depressive disorder

Objective

This study evaluated the treatment outcomes of agomelatine on anhedonic state, anxiety/somatic symptoms, and sexual function in Chinese patients with major depressive disorder (MDD).

Method

In total, 93 adult patients with MDD were enrolled, and 68 of them were included in a prospective, open-label, multicenter clinical study. All patients received agomelatine monotherapy during a 9-week treatment phase. The effectiveness of the treatment was reflected by the improvement of anhedonia and somatic symptoms based on the 17-item Hamilton Depression Rating Scale (HAMD-17). In addition, the Arizona Sexual Dysfunction Scale (ASEX), Sheehan Disability Scale (SDS), and Short Form of Quality-of-Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q-SF) were administered to all participants at baseline and at the 3-, 6-, and 9-week follow-ups.

Results

After 9 weeks of treatment with agomelatine, the response and remission rates were 73.5% and 39.7%, respectively. Somatic symptoms significantly improved at week 9 (p < 0.001), and significant effects were also observed on the HAMD anhedonia items (p < 0.001). The patients exhibited lower levels of disease severity (the SDS score dropped from 15.52 ± 4.7 to 7.09 ± 5.62 at week 9; the ASEX score dropped from 21.89 ± 4.06 to 16.19 ± 4.79, p < 0.001) and higher levels of QOL (the Q-LES-Q-SF score dropped from 41.02 ± 5.99 to 50.49 ± 8.57, p < 0.001) during the follow-up. Furthermore, treatment with agomelatine improved depressive symptoms without causing serious adverse events.

Conclusion

These analyses indicate that agomelatine is a treatment option for improving anhedonic status, anxiety/somatic symptoms, and sexual dysfunction in MDD patients.

Agomelatine, Ketamine and Vortioxetine Attenuate Energy Cell Metabolism-In Vitro Study

This determination of the mitochondrial effect of pharmacologically different antidepressants (agomelatine, ketamine and vortioxetine) was evaluated and quantified in vitro in pig brain-isolated mitochondria. We measured the activity of mitochondrial complexes, citrate synthase, malate dehydrogenase and monoamine oxidase, and the mitochondrial respiratory rate. Total hydrogen peroxide production and ATP production were assayed. The most potent inhibitor of all mitochondrial complexes and complex I-linked respiration was vortioxetine. Agomelatine and ketamine inhibited only complex IV activity. None of the drugs affected complex II-linked respiration, citrate synthase or malate dehydrogenase activity. Hydrogen peroxide production was mildly increased by agomelatine, which might contribute to increased oxidative damage and adverse effects at high drug concentrations. Vortioxetine significantly reduced hydrogen peroxide concentrations, which might suggest antioxidant mechanism activation. All tested antidepressants were partial MAO-A inhibitors, which might contribute to their antidepressant effect. We observed vortioxetine-induced MAO-B inhibition, which might be linked to decreased hydrogen peroxide formation and contribute to its procognitive and neuroprotective effects. Mitochondrial dysfunction could be linked to the adverse effects of vortioxetine, as vortioxetine is the most potent inhibitor of mitochondrial complexes and complex I-linked respiration. Clarifying the molecular interaction between drugs and mitochondria is important to fully understand their mechanism of action and the connection between their mechanisms and their therapeutic and/or adverse effects.

Associations between treatment with melatonin and suicidal behavior: a nationwide cohort study

STUDY OBJECTIVES

Melatonin is often prescribed to patients with sleep disorders who are known to have elevated suicide risks, yet melatonin's association with suicidal behavior remains to be examined. We investigated whether individuals prescribed melatonin had higher rates of suicide and suicide attempts when compared to individuals who were not prescribed this drug, including both those with and without known mental disorders.

METHODS

A cohort design was applied to longitudinal, register data on all persons aged ≥ 10 years in Denmark during 2007-2016. Based on data from the National Prescription Registry, periods of being in treatment with melatonin were defined using information on the number of tablets and the daily defined dose. We calculated incidence rate ratios for suicide and suicide attempts, as identified in register records, comparing those in treatment with melatonin to those not in treatment.

RESULTS

Among 5,798,923 individuals, 10,577 (0.2%) were treated with melatonin (mean treatment length, 50 days) during the study period. Of those, 22 died by suicide and 134 had at least 1 suicide attempt. People in treatment with melatonin had a 4-fold higher rate of suicide (incidence rate ratio, 4.8; 95% CI, 3.0-7.5) and a 5-fold higher rate of suicide attempt (incidence rate ratio, 5.9; 95% CI, 4.4-8.0) than those not in treatment and when adjusting for sex and age group.

CONCLUSIONS

Treatment with melatonin was associated with suicide and suicide attempt. Although there are several possible explanations, attention to suicide risk is particularly warranted for people with mental comorbidity who are in treatment with melatonin.

CITATION

Høier NK, Madsen T, Spira AP, et al. Associations between treatment with melatonin and suicidal behavior: a nationwide cohort study. J Clin Sleep Med. 2022;18(10):2451-2458.

Radiosynthesis and In Vivo Evaluation of Four Positron Emission Tomography Tracer Candidates for Imaging of Melatonin Receptors

Melatonin is a neurohormone that modulates several physiological functions in mammals through the activation of melatonin receptor type 1 and 2 (MT₁ and MT₂). The melatonergic system is an emerging therapeutic target for new pharmacological interventions in the treatment of sleep and mood disorders; thus, imaging tools to further investigate its role in the brain are highly sought-after. We aimed to develop selective radiotracers for in vivo imaging of both MT₁ and MT₂ by positron emission tomography (PET). We identified four previously reported MT ligands with picomolar affinities to the target based on different scaffolds which were also amenable for radiolabeling with either carbon-11 or fluorine-18. [¹¹C]UCM765, [¹¹C]UCM1014, [¹⁸F]3-fluoroagomelatine ([¹⁸F]3FAGM), and [¹⁸F]fluoroacetamidoagomelatine ([¹⁸F]FAAGM) have been synthesized in high radiochemical purity and evaluated in wild-type rats. All four tracers showed moderate to high brain permeability in rats with maximum standardized uptake values (SUV_max of 2.53, 1.75, 3.25, and 4.47, respectively) achieved 1-2 min after tracer administration, followed by a rapid washout from the brain. Several melatonin ligands failed to block the binding of any of the PET tracer candidates, while in some cases, homologous blocking surprisingly resulted in increased brain retention. Two ¹⁸F-labeled agomelatine derivatives were brought forward to PET scans in non-human primates and autoradiography on human brain tissues. No specific binding has been detected in blocking studies. To further investigate pharmacokinetic properties of the putative tracers, microsomal stability, plasma protein binding, log D, and membrane bidirectional permeability assays have been conducted. Based on the results, we conclude that the fast first pass metabolism by the enzymes in liver microsomes is the likely reason of the failure of our PET tracer candidates. Nevertheless, we showed that PET imaging can serve as a valuable tool to investigate the brain permeability of new therapeutic compounds targeting the melatonergic system.

Agomelatine Prevents Amyloid Plaque Deposition, Tau Phosphorylation, and Neuroinflammation in APP/PS1 Mice

Agomelatine, an agonist of melatonergic MT1 and MT2 receptors and a selective 5-hydroxytryptamine 2C receptor antagonist, is widely applied in treating depression and insomnia symptoms in several neurogenerative diseases. However, the neuroprotective effect of agomelatine in Alzheimer’s disease (AD) is less known. In this study, a total of 30 mice were randomly divided into three groups, namely, wild type (WT), APP/PS1, and agomelatine (50 mg/kg). After 30 days, the Morris water maze was performed to test the cognitive ability of mice. Then, all mice were sacrificed, and the hippocampus tissues were collected for ELISA, Western blot, and immunofluorescence analysis. In this study, we found that agomelatine attenuated spatial memory deficit, amyloid-β (Aβ) deposition, tau phosphorylation, and neuroinflammation in the hippocampus of APP/PS1 mice. Further study demonstrated that agomelatine treatment upregulated the protein expression of DHCR24 and downregulated P-Akt, P-mTOR, p-p70s6k, Hes1, and Notch1 expression. In summary, our results identified that agomelatine could improve cognitive impairment and ameliorate AD-like pathology in APP/PS1 mice via activating DHCR24 signaling and inhibiting Akt/mTOR and Hes1/Notch1 signaling pathway. Agomelatine may become a promising drug candidate in the therapy of AD.

Associations between Melatonin, Neuroinflammation, and Brain Alterations in Depression

Pro-inflammatory systemic conditions that can cause neuroinflammation and subsequent alterations in brain regions involved in emotional regulation have been suggested as an underlying mechanism for the pathophysiology of major depressive disorder (MDD). A prominent feature of MDD is disruption of circadian rhythms, of which melatonin is considered a key moderator, and alterations in the melatonin system have been implicated in MDD. Melatonin is involved in immune system regulation and has been shown to possess anti-inflammatory properties in inflammatory conditions, through both immunological and non-immunological actions. Melatonin has been suggested as a highly cytoprotective and neuroprotective substance and shown to stimulate all stages of neuroplasticity in animal models. The ability of melatonin to suppress inflammatory responses through immunological and non-immunological actions, thus influencing neuroinflammation and neurotoxicity, along with subsequent alterations in brain regions that are implicated in depression, can be demonstrated by the antidepressant-like effects of melatonin. Further studies that investigate the associations between melatonin, immune markers, and alterations in the brain structure and function in patients with depression could identify potential MDD biomarkers.

Agomelatine: An astounding sui-generis antidepressant?

Major depressive disorder (MDD) is one of the foremost causes of disability and premature death worldwide. Although the available antidepressants are effective and well tolerated, they also have many limitations. Therapeutic advances in developing a new drug's ultimate relation between MDD and chronobiology, which targets the circadian rhythm, have led to a renewed focus on psychiatric disorders. In order to provide a critical analysis about antidepressant properties of agomelatine, a detailed PubMed (Medline), Scopus (Embase), Web of Science (Web of Knowledge), Cochrane Library, Google Scholar, and PsycInfo search was performed using the following keywords: melatonin analog, agomelatine, safety, efficacy, adverse effects, pharmacokinetics, pharmacodynamics, circadian rhythm, sleep disorders, neuroplasticity, MDD, bipolar disorder, anhedonia, anxiety, generalized anxiety disorder (GAD), and mood disorders. Agomelatine is a unique melatonin analog with antidepressant properties and a large therapeutic index that improves clinical safety. It is a melatonin receptor agonist (MT1 and MT2) and a 5-HT2C receptor antagonist. The effects on melatonin receptors enable the resynchronization of irregular circadian rhythms with beneficial effects on sleep architectures. In this way, agomelatine is accredited for its unique mode of action, which helps to exert antidepressant effects and resynchronize the sleep-wake cycle. To sum up, an agomelatine has not only antidepressant properties but also has anxiolytic effects.

Korean Medication Algorithm for Depressive Disorder 2021, Fourth Revision: An Executive Summary

Objective

In the 19 years since the Korean College of Neuropsychopharmacology and the Korean Society for Affective Disorders developed the Korean Medication Algorithm Project for Depressive Disorder (KMAP-DD) in 2002, four revisions have been conducted.

Methods

To increase survey efficiency in this revision, to cover the general clinical practice, and to compare the results with previous KMAP-DD series, the overall structure of the questionnaire was maintained. The six sections of the questionnaire were as follows: 1) pharmacological treatment strategies for major depressive disorder (MDD) with/without psychotic features; 2) pharmacological treatment strategies for persistent depressive disorder and other depressive disorder subtypes; 3) consensus for treatment-resistant depression; 4) the choice of an antidepressant in the context of safety, adverse effects, and comorbid physical illnesses; 5) treatment strategies for special populations (children/adolescents, elderly, and women); and 6) non-pharmacological biological therapies. Recommended first-, second-, and third-line strategies were derived statistically.

Results

There has been little change in the four years since KMAP-DD 2017 due to the lack of newly introduced drug or treatment strategies. However, shortened waiting time between the initial and subsequent treatments, increased preference for atypical antipsychotics (AAPs), especially aripiprazole, and combination strategies with AAPs yield an active and somewhat aggressive treatment trend in Korea.

Conclusion

We expect KMAP-DD to provide clinicians with useful information about the specific strategies and medications appropriate for treating patients with MDD by bridging the gap between clinical real practice and the evidence-based world.

Update on the Relationship Between Depression and Neuroendocrine Metabolism

Through the past decade of research, the correlation between depression and metabolic diseases has been noticed. More and more studies have confirmed that depression is comorbid with a variety of metabolic diseases, such as obesity, diabetes, metabolic syndrome and so on. Studies showed that the underlying mechanisms of both depression and metabolic diseases include chronic inflammatory state, which is significantly related to the severity. In addition, they also involve endocrine, immune systems. At present, the effects of clinical treatments of depression is limited. Therefore, exploring the co-disease mechanism of depression and metabolic diseases is helpful to find a new clinical therapeutic intervention strategy. Herein, focusing on the relationship between depression and metabolic diseases, this manuscript aims to provide an overview of the comorbidity of depression and metabolic.

Anhedonia as a central factor in depression: Neural mechanisms revealed from preclinical to clinical evidence

Anhedonia is one of the core symptoms of major depressive disorder (MDD), which is often inadequately treated by traditional antidepressants. The modern framework of anhedonia extends the definition from impaired consummatory pleasure or interest in rewards to a broad spectrum of deficits that impact functions such as reward anticipation, approach motivation, effort expenditure, reward valuation, expectation, and reward-cue association learning. Substantial preclinical and clinical research has explored the neural basis of reward deficits in the context of depression, and has implicated mesocorticolimbic reward circuitry comprising the nucleus accumbens, ventral pallidum, ventral tegmental area, amygdala, hippocampus, anterior cingulate, insula, orbitofrontal cortex, and other prefrontal cortex regions. Dopamine modulates several reward facets including anticipation, motivation, effort, and learning. As well, serotonin, norepinephrine, opioids, glutamate, Gamma aminobutyric acid (GABA), and acetylcholine are also involved in anhedonia, and medications targeting these systems may also potentially normalize reward processing in depression. Unfortunately, whereas reward anticipation and reward outcome are extensively explored by both preclinical and clinical studies, translational gaps remain in reward motivation, effort, valuation, and learning, where clinical neuroimaging studies are in the early stages. This review aims to synthesize the neurobiological mechanisms underlying anhedonia in MDD uncovered by preclinical and clinical research. The translational difficulties in studying the neural basis of reward are also discussed.

Depression, antidepressants and fall risk: therapeutic dilemmas-a clinical review

PURPOSE

The aim of this clinical review was to summarize the existing knowledge on fall risk associated with antidepressant use in older adults, describe underlying mechanisms, and assist clinicians in decision-making with regard to (de-) prescribing antidepressants in older persons.

METHODOLOGY

We comprehensively examined the literature based on a literature search in Pubmed and Google Scholar, and identified additional relevant articles from reference lists, with an emphasis on the most commonly prescribed drugs in depression in geriatric patients. We discuss use of antidepressants, potential fall-related side effects, and deprescribing of antidepressants in older persons.

RESULTS

Untreated depression and antidepressant use both contribute to fall risk. Antidepressants are equally effective, but differ in fall-related side effect profile. They contribute to (or cause) falling through orthostatic hypotension, sedation/impaired attention, hyponatremia, movement disorder and cardiac toxicity. Falling is an important driver of morbidity and mortality and, therefore, requires prevention. If clinical condition allows, withdrawal of antidepressants is recommended in fall-prone elderly persons. An important barrier is reluctance of prescribers to deprescribe antidepressants resulting from fear of withdrawal symptoms or disease relapse/recurrence, and the level of complexity of deprescribing antidepressants in older persons with multiple comorbidities and medications. Practical resources and algorithms are available that guide and assist clinicians in deprescribing antidepressants.

CONCLUSIONS

(De-) prescribing antidepressants in fall-prone older adults is often challenging, but detailed insight in fall-related side effect profile of the different antidepressants and a recently developed expert-based decision aid STOPPFalls assists prescribers in clinical decision-making.

Sleep Disturbance, Sleep Disorders and Co-Morbidities in the Care of the Older Person

Sleep complaints can be both common and complex in the older patient. Their consideration is an important aspect of holistic care, and may have an impact on quality of life, mortality, falls and disease risk. Sleep assessment should form part of the comprehensive geriatric assessment. If sleep disturbance is brought to light, consideration of sleep disorders, co-morbidity and medication management should form part of a multifaceted approach. Appreciation of the bi-directional relationship and complex interplay between co-morbidity and sleep in older patients is an important element of patient care. This article provides a brief overview of sleep disturbance and sleep disorders in older patients, in addition to their association with specific co-morbidities including depression, heart failure, respiratory disorders, gastro-oesophageal reflux disease, nocturia, pain, Parkinson's disease, dementia, polypharmacy and falls. A potential systematic multidomain approach to assessment and management is outlined, with an emphasis on non-pharmacological treatment where possible.

Molecular Regulation of the Melatonin Biosynthesis Pathway in Unipolar and Bipolar Depression

Melatonin is a neurohormone that maintains the circadian rhythms of the body. By regulating the secretion of other hormones and neurotransmitters, it acts as a pleiotropic modulator that affects, for example, reproductive, immune, cardiovascular, sleep, and wake systems and mood. Thus, synthetic melatonin has become an essential component in the treatment of depressive disorders. Although we know the pathway of melatonin action in the brain, we lack comprehensive cross-sectional studies on the periphery of depressed patients. This study aimed to comprehensively analyze the differences between healthy control subjects (n = 84) and unipolar and bipolar depression patients (n = 94), including an analysis of the melatonin pathway at the level of the genes and serum biomarkers. An innovative approach is a pilot study based on gene expression profiling carried out on clinical and cell culture models using agomelatine and melatonin. We confirmed the melatonin biosynthesis pathway's molecular regulation dysfunctions, with a specific pattern for unipolar and bipolar depression, at the AANAT gene, its polymorphisms (rs8150 and rs3760138), and examined the serum biomarkers (serotonin, AANAT, ASMT, and melatonin). The biological pathway analysis uncovered pathways and genes that were uniquely altered after agomelatine treatment in a clinical model and melatonin treatment in a cell culture model. In both models, we confirmed the immunomodulatory effect of melatonin agents in depression.

Serotonin 2 Receptors, Agomelatine, and Behavioral and Psychological Symptoms of Dementia in Alzheimer's Disease

There are nearly 50 million Alzheimer's disease (AD) patients worldwide, 90% of whom develop behavioral and psychological symptoms of dementia (BPSD), which increase the mortality rate of patients, and impose an economic and care burden on families and society. As a neurotransmitter and neuromodulator, serotonin is involved in the regulation of psychoemotional, sleep, and feeding functions. Accumulating data support the importance of serotonin in the occurrence and development of BPSD. Studies have shown that reduction of serotonin receptors can increase depression and mental symptoms in AD patients. At present, there is no drug treatment for AD approved by the US Food and Drug Administration. Among them, agomelatine, as a new type of antidepressant, can act on serotonin 2 receptors to improve symptoms such as depression and anxiety. At present, research on BPSD is still in the preliminary exploratory stage, and there are still a lot of unknowns. This review summarizes the relationship between serotonin 2 receptors, agomelatine, and BPSD. It provides a new idea for the study of the pathogenesis and treatment of BPSD.

New agents and perspectives in the pharmacological treatment of major depressive disorder

Despite the important advances in the understanding of the pathophysiology of MDD, a large proportion of depressed patients do not respond well to currently available pharmacological agents. The present review focuses on new targets and future directions in the pharmacological treatment of MDD. Novel agents and their efficacy in the treatment of depression are discussed, with a focus on the respectively target pathophysiological pathways and the level of available evidence. Although it is expected that classic antidepressants will remain the cornerstone of MDD treatment, at least for the near future, a large number of novel compounds is currently under investigation as for their efficacy in the treatment of MDD, many of which with promising results.

Agomelatine, A Potential Multi-Target Treatment Alternative for Insomnia, Depression, and Osteoporosis in Postmenopausal Women: A Hypothetical Model

Insomnia, which is associated with menopausal depression, is a common symptom of menopause. Both symptoms have a common etiology, and can affect each other significantly. Pharmacological interventions, including hypnotics and antidepressants, and non-pharmacological therapies are generally administered in clinical practice for insomnia treatment. As another menopausal disorder, osteoporosis is described as a disease of low bone mineral density (BMD), affecting nearly 200 million women worldwide. Postmenopausal osteoporosis is common among middle-aged women. Since postmenopausal osteoporosis mainly results from low estrogen levels, menopausal hormone therapy (HT) is considered the first-line option for the prevention of osteoporosis during the menopausal period. However, almost no study has evaluated novel treatments for the combined prevention of insomnia, depression, and osteoporosis. Hence, it is necessary to develop new multi-target strategies for the treatment of these disorders to improve the quality of life during this vulnerable period. Melatonin is the major regulator of sleep, and it has been suggested to be safe and effective for bone loss therapy by MT-2 receptor activity. As a result, we hypothesize that agomelatine, an MT-1 and MT-2 receptor agonist and 5-HT_2C receptor antagonist, holds promise in the combined treatment of insomnia, depression, and osteoporosis in middle-aged women during menopause.

Drug-Drug Interactions Involving Intestinal and Hepatic CYP1A Enzymes

Cytochrome P450 (CYP) 1A enzymes are considerably expressed in the human intestine and liver and involved in the biotransformation of about 10% of marketed drugs. Despite this doubtless clinical relevance, CYP1A1 and CYP1A2 are still somewhat underestimated in terms of unwanted side effects and drug–drug interactions of their respective substrates. In contrast to this, many frequently prescribed drugs that are subjected to extensive CYP1A-mediated metabolism show a narrow therapeutic index and serious adverse drug reactions. Consequently, those drugs are vulnerable to any kind of inhibition or induction in the expression and function of CYP1A. However, available in vitro data are not necessarily predictive for the occurrence of clinically relevant drug–drug interactions. Thus, this review aims to provide an up-to-date summary on the expression, regulation, function, and drug–drug interactions of CYP1A enzymes in humans.

Agomelatine for the Treatment of Generalized Anxiety Disorder: A Meta-Analysis

Objective

Despite multiple drugs available, a large proportion of patients with generalized anxiety disorder (GAD) do not show adequate response and remission. Thus, additional novel pharmacological agents are needed to increase treatment option for GAD. We aimed to investigate efficacy and safety of agomelatine in the treatment of GAD by conducting a meta-analysis.

Methods

An extensive search of multiple databases and clinical trial registries were conducted. Mean change in total scores on Hamilton Anxiety Rating Scale (HAM-A) from baseline to endpoint was our primary outcome measure. Secondary efficacy measures included response and remission rates, as defined by a 50% or greater reduction in HAM-A total scores and a score of 7 or less in HAM-A total scores at study endpoint respectively.

Results

Four published double blinded, randomized, placebo-controlled trials were included in this meta-analysis. Agomelatine more significantly (standardized mean difference = −0.56, p = 0.004) improved HAM-A total scores than placebo. The odds ratios (ORs) of agomelatine over placebo for response and remission rates were 3.75 (p < 0.00001) and 2.74 (p < 0.00001), respectively. Agomelatine was generally well tolerated with insignificance in dropout rate, somnolence, headache, nasopharyngitis, and dizziness compared with placebo. However, agomelatine showed significantly higher incidence of liver function increment (OR = 3.13, p = 0.01) and nausea (OR = 3.27, p = 0.02).

Conclusion

We showed that agomelatine may be another treatment option in patients with GAD. However, the results should be interpreted and translated into clinical practice with caution because the meta-analysis was based on limited numbers of clinical trials.

The preclinical discovery and development of agomelatine for the treatment of depression

INTRODUCTION

Under the treatment of commonly used antidepressants, many patients with major depressive disorder (MDD) do not achieve remission. All previous first-line treatments for depression have focused on the enhancement of monoaminergic activity. Agomelatine was the first antidepressant with a mechanism of action extending beyond monoaminergic neurotransmission.

AREAS COVERED

The aim of this case history is to describe the discovery strategy and development of agomelatine. The pharmacodynamic profile of the drug is briefly presented. The article summarizes (a) the preclinical behavioral data on agomelatine's effects on depressive-like behavior, anxiety, and circadian rhythmicity disruptions, and (b) the results of early preclinical studies on safety, efficacy in MDD, and the risk-benefit pharmacological profile. Furthermore, the article examines findings of post-marketing research on safety, efficacy, and cost-effectiveness of the drug.

EXPERT OPINION

There is now evidence supporting the clinical efficacy and safety profile of agomelatine in the acute-phase treatment of MDD. Agomelatine may be more effective in specific subgroups of MDD patients, those with severe anxiety symptoms or disturbed circadian profiles. Its antidepressant and anxiolytic activities are due to synergy between its melatonergic and 5-hydroxytryptaminergic effects. Since its discovery, novel compounds acting on the melatonergic system have been under investigation for the treatment of MDD.

Hypotensive Effect of Nanomicellar Formulation of Melatonin and Agomelatine in a Rat Model: Significance for Glaucoma Therapy

BACKGROUND

Melatoninergic agents are known to reduce intraocular pressure (IOP). The present study was performed to evaluate the effect of nanomicellar formulations of melatoninergic agents on IOP in the rat.

METHODS

Tonometry was used to measure IOP in eyes instilled with melatonin or agomelatine. Ocular hypertension was induced by the injection of methylcellulose in the anterior chamber.

RESULTS

Melatonin formulated in nanomicelles had a longer lasting hypotonizing effect on IOP with respect to melatonin in saline. Nanomicellar formulations of melatonin and agomelatine, either alone or in combination, had lowering effects that did not depend on their concentration or their combination, which, however, resulted in an increased duration of the hypotonizing effect. The duration of the lowering effect was further increased by the addition of lipoic acid.

CONCLUSIONS

We demonstrated the effective hypotonizing activity of melatonin and agomelatine in combination with lipoic acid. Although results in animals cannot be directly translated to humans, the possibility of developing novel therapeutical approaches for patients suffering from hypertensive glaucoma should be considered.

Analysis of Time-Course, Dose-Effect, and Influencing Factors of Antidepressants in the Treatment of Acute Adult Patients With Major Depression

OBJECTIVE

Model-based meta-analysis was used to describe the time-course and dose-effect relationships of antidepressants and also simultaneously investigate the impact of various factors on drug efficacy.

METHODS

This study is a reanalysis of a published network meta-analysis. Only placebo-controlled trials were included in this study. The change rate in depression rating scale scores from baseline was used as an efficacy indicator because a continuous variable is more likely to reflect subtle differences in efficacy between drugs.

RESULTS

A total 230 studies containing 64 346 patients were included in the analysis. The results showed that the number of study sites (single or multi-center) and the type of setting (inpatient or noninpatient) are important factors affecting the efficacy of antidepressants. After deducting the placebo effect, the maximum pure drug efficacy value of inpatients was 18.4% higher than that of noninpatients, and maximum pure drug efficacy value of single-center trials was 10.2% higher than that of multi-central trials. Amitriptyline showed the highest drug efficacy. The remaining 18 antidepressants were comparable or had little difference. Within the approved dose range, no significant dose-response relationship was observed. However, the time-course relationship is obvious for all antidepressants. In terms of safety, with the exception of amitriptyline, the dropout rate due to adverse events of other drugs was not more than 10% higher than that of the placebo group.

CONCLUSION

The number of study sites and the type of setting are significant impact factors for the efficacy of antidepressants. Except for amitriptyline, the other 18 antidepressants have little difference in efficacy and safety.