Gastrointestinal Microbiome and related metabolites in Depression and Antidepressants - a comprehensive review

Depression,a prevalent mood disorder,has emerged as a significant health concern in society.While the exact cause of depression remains incompletely understood,there is substantial evidence linking the gastrointestinal microbiome and its metabolites to this condition.Through combined multi-omics analysis,it has been observed that the composition of the gastrointestinal microbiome,including Firmicutes,Bacteroidetes,and Actinobacteria,undergoes significant alterations in depressed individuals.Moreover,the production of short-chain fatty acids,tryptophan,and bile acids by these gut microbes is also found to be modified in depression.Furthermore,studies have demonstrated that antidepressant medications exert their therapeutic effects by interacting with the gastrointestinal microbiome and their metabolites.This review provides an overview of the association between the gastrointestinal microbiome,related metabolites,and depression.It highlights the potential of these factors to serve as mechanisms of action for antidepressant medications.Additionally,the review summarizes the commonly used technical tools in depression research.

A Case Study of Severe QT Interval Prolongation Caused by Antidepressants

QT interval prolongation can be categorized into primary and secondary types according to its etiology.In this paper,we report a case of severe asymptomatic QT interval prolongation secondary to antidepressants.Regular follow-up and electrocardiogram monitoring is crucial when applying antidepressants,especially for patients without cardiac symptoms.This article presents case studies and examines existing literature on long QT syndrome to enhance the diagnosis and management of QT interval prolongation.This is especially relevant for non-psychiatric healthcare professionals who need to be attentive to the side effects of antidepressants to prevent potential adverse consequences resulting from oversight.

Effi cacy of tricyclic antidepressants in irritable bowel syndrome:A meta-analysis

We aimed to evaluate the efficacy of tricyclic antidepressants(TCAs) as a therapeutic option for irritable bowel syndrome(IBS) through meta-analysis of randomized controlled trials.For the years 1966 until September 2008,PubMed,Scopus,Web of Science,and Cochrane Central Register of Controlled Trials were searched for double-blind,placebo-controlled trials investigating the effi cacy of TCAs in the management of IBS.Seven randomized,placebo-controlled clinical trials met our criteria and were included in the metaanalysis.TCAs used in the treatment arm of these trials included amitriptyline,imipramine,desipramine,doxepin and trimipramine.The pooled relative risk for clinical improvement with TCA therapy was 1.93(95% CI:1.44 to 2.6,P<0.0001).Effect size of TCAs versus placebo for mean change in abdominal pain score among the two studies was -44.15(95% CI:-53.27 to -35.04,P<0.0001).It is concluded that low dose TCAs exhibit clinically and statistically signifi cant control of IBS symptoms.

Depressive disorder and antidepressants from an epigenetic point of view

Depressive disorder is a complex,heterogeneous disease that affects approximately 280 million people worldwide.Environmental,genetic,and neurobiological factors contribute to the depressive state.Since the nervous system is susceptible to shifts in activity of epigenetic modifiers,these allow for significant plasticity and response to rapid changes in the environment.Among the most studied epigenetic modifications in depressive disorder is DNA methylation,with findings centered on the brain-derived neurotrophic factor gene,the glucocorticoid receptor gene,and the serotonin transporter gene.In order to identify biomarkers that would be useful in clinical settings,for diagnosis and for treatment response,further research on antidepressants and alterations they cause in the epigenetic landscape throughout the genome is needed.Studies on cornerstone antidepressants,such as selective serotonin reuptake inhibitors,selective serotonin and norepinephrine reuptake inhibitors,norepinephrine,and dopamine reuptake inhibitors and their effects on depressive disorder are available,but systematic conclusions on their effects are still hard to draw due to the highly heterogeneous nature of the studies.In addition,two novel drugs,ketamine and esketamine,are being investigated particularly in association with treatment of resistant depression,which is one of the hot topics of contemporary research and the field of precision psychiatry.

Single Exposure to Antidepressants during Infancy Is Associated with Delayed Behavioral Changes in C57BL/6 Mice

As serotoninergic transmission plays a crucial role in higher brain function in mammals, the disturbance of this system will likely have significant effects on emotion and cognition. Previous studies have reported that chronic treatment with Specific Serotonin Reuptake Inhibitors (SSRIs) during both late pregnancy and lactation was associated with abnormal behavior in adult rats. These data imply that disturbances in serotoninergic transmission during neurodevelopment may have negative effects on both the structure and function of the resultant adult brain. Therefore, the effect of a single exposure to an SSRI or a tricyclic antidepressant that preferentially inhibits serotonin reuptake during the pre-weaning period was examined in adult mice. An oral infusion of paroxetine (70 mg/kg), fluvoxamine (250 mg/kg), clomipramine (180 mg/kg), or saline was administered on postnatal day 14. Starting at 11 weeks of age, mice were assessed using a comprehensive behavioral test battery. Mice treated with paroxetine demonstrated altered behavior on the open field and hole-board tasks;those treated with fluvoxamine had behavioral changes on the light-dark box, hole-board, and sucrose preference tasks, while alteration in forced swimming and cued fear behavior were noted in mice treated with clomipramine. These results suggest that even a single administration of an antidepressant could have profound effects on behavior in adulthood, although the effects might differ dependent on the specific drug that was administered.

Antidepressants can treat inflammatory bowel disease through regulation of the nuclear factor-κB/nitric oxide pathway and inhibition of cytokine production:A hypothesis

Inflammatory bowel disease (IBD) is a group of inflammatory disorders mainly affecting the colon and small intestine. The main types of IBD are Crohn’s disease (CD) and ulcerative colitis (UC). UC is restricted to the large intestine whereas CD can affect any part of the gastrointestinal tract. Treating this disorder depends on the form and level of severity. Common treatment involves an anti-inflammatory drug, such as mesalazine, and an immunosuppressant, such as prednisone. Several signaling pathways, including nuclear factor (NF)-κB and nitric oxide (NO), and genetic and environmental factors are believed to play an important role in IBD. Amitriptyline is a commonly used antidepressant with known anti-inflammatory activities. Amitriptyline also acts on the NF-κB/NO pathway or cytokine production. Therefore, we hypothesize that antidepressants like amitriptyline can be pioneered and considered effective as an innovative and effective therapeutic in the treatment and attenuation of development of IBD in adjusted doses.

Antidepressants for bipolar disorder A meta-analysis of randomized, double-blind, controlled trials

OBJECTIVE： To examine the efficacy and safety of short-term and long-term use of antidepres- sants in the treatment of bipolar disorder. DATA SOURCES： A literature search of randomized, double-blind, controlled trials published until December 2012 was performed using the PubMed, ISI Web of Science, Medline and Cochrane Central Register of Controlled Trials databases. The keywords ＂bipolar disorder, bipolar I disorder, bipolar II disorder, bipolar mania, bipolar depression, cyclothymia, mixed mania and depression, rapid cycling and bipolar disorder＂, AND ＂antidepressant agent, antidepressive agents second- generation, antidepressive agents tricyclic, monoamine oxidase inhibitor, noradrenaline uptake in- hibitor, serotonin uptake inhibitor, and tricyclic antidepressant agent＂ were used. The studies that were listed in the reference list of the published papers but were not retrieved in the above-mentioned databases were supplemented. STUDY SELECTION： Studies selected were double-blind randomized controlled trials assessing the efficacy and safety of antidepressants in patients with bipolar disorder. All participants were aged 18 years or older, and were diagnosed as having primary bipolar disorder. Antidepressants or antidepressants combined with mood stabilizers were used in experimental interventions. Placebos, mood stabilizers, antipsychotics and other antide pressants were used in the control interventions. Studies that were quasi-randomized studies, or used antidepressants in combination with antipsy- chotics in the experimental group were excluded. All analyses were conducted using Review Man- ager 5.1 provided by the Cochrane Collaboration.

Novel antidepressants targeting TREK1 channel

OBJECTIVE To find that the extracellular cap of a K2P channel can act as a new allosteric site and may serve as a direct drug target.METHODS Molecular biology and cell transfection,electrophysiology,molecular docking,molecular dynamics simulations,virtual screening for TREK1,and depressive-related behavior tests.RESULTS Extracellular domain of TREK1 channel existed a dynamic cavity in the extracellular domain by the method of computations,mutagenesis and electrophysiology.Molecular dynamics simulations suggested that ligand-induced allosteric conformational transitions lead to blockage of the ion conductive pathway.Using virtual screening approach,we identified other inhibitors targeting the extracellular allosteric ligand-binding site of these channels.Overall,our results suggested that the allosteric site at the extracellular cap of the K2P channels might be a promising drug target for these membrane proteins.The TREK1 inhibitor TKDC had significantly faster onset than that of fluoxetine in chronic administration trials,and the study confirms that TREK1 was an important target for the development of rapid antidepressants.CONCLUSION The study is a significant step forward for understanding the function of TREK and for identifying specific inhibitors,which should be of interest to others in the field.

The role of selective serotonin reuptake inhibitors and tricyclic antidepressants in addressing reduction of Meniere's disease burden:A scoping review

Objective:To assess the effect of selective serotonin reuptake inhibitors(SSRIs)and tricyclic antidepressants(TCAs)in reducing vertigo,tinnitus,and hearing loss among patients with Meniere's disease(MD).Data Sources:The following databases were utilized in this scoping review:Ovid Medline,PubMed-NCBI,CINAHL,Cochrane Library,Web of Science,and Clinicaltrials.gov.Method:Studies were identified through the following search phrases:"serotonin specific reuptake inhibitors"OR"tricyclic antidepressants"AND"Meniere's disease."References from included manuscripts were examined for possible inclusion of additional studies.Results:The literature search yielded 23 results,which were screened by three independent reviewers.Seventeen studies and three duplicates were excluded.An examination of references from the included studies yielded two additional publications.A total of four published studies assessing SSRIs and TCAs among 147 patients with MD were ultimately included.Four studies described significant reductions in vertigo attack frequency among patients treated with either SSRIs or TCAs compared to their pretreatment baseline.Three studies assessed the drugs'effects on hearing,of which none found a significant difference among patients treated with SSRIs or TCAs.One study found a significant decrease in patient-reported tinnitus following treatment with TCAs or SSRIs compared to their pretreatment baseline.Conclusions:Data exploring SSRIs and TCAs among patients with MD suggests that these medications may reduce the frequency of tinnitus and vertigo,although there was significant heterogeneity in outcome reporting.There remains a need for larger-scale prospective studies that emphasize objective data to evaluate their effective-ness in reducing common MD symptoms.

Potential role of hippocampal neurogenesis in spinal cord injury induced post-trauma depression

It has been reported both in clinic and rodent models that beyond spinal cord injury directly induced symptoms, such as paralysis, neuropathic pain, bladder/bowel dysfunction, and loss of sexual function, there are a variety of secondary complications, including memory loss, cognitive decline, depression, and Alzheimer's disease. The largescale longitudinal population-based studies indicate that post-trauma depression is highly prevalent in spinal cord injury patients. Yet, few basic studies have been conducted to address the potential molecular mechanisms. One of possible factors underlying the depression is the reduction of adult hippocampal neurogenesis which may come from less physical activity, social isolation, chronic pain, and elevated neuroinflammation after spinal cord injury. However, there is no clear consensus yet. In this review, we will first summarize the alteration of hippocampal neurogenesis post-spinal cord injury. Then, we will discuss possible mechanisms underlie this important spinal cord injury consequence. Finally, we will outline the potential therapeutic options aimed at enhancing hippocampal neurogenesis to ameliorate depression.

Serotonin syndrome controversies:A need for consensus

Serotonin syndrome(SS)is a drug-induced clinical syndrome resulting from increased serotonergic activity in the central nervous system.Although more than seven decades have passed since the first description of SS,it is still an enigma in terms of terminology,clinical features,etiology,pathophysiology,diagnostic criteria,and therapeutic measures.The majority of SS cases have previously been reported by toxicology or psychiatry centers,particularly in people with mental illness.However,serotonergic medications are used for a variety of conditions other than mental illness.Serotonergic properties have been discovered in several new drugs,including over-the-counter medications.These days,cases are reported in non-toxicology centers,such as perioperative settings,neurology clinics,cardiology settings,gynecology settings,and pediatric clinics.Overdoses or poisonings of serotonergic agents constituted the majority of the cases observed in toxicology or psychiatry centers.Overdose or poisoning of serotonergic drugs is uncommon in other clinical settings.Patients may develop SS at therapeutic dosages.Moreover,these patients may continue to use serotonergic medications even if they develop mild to moderate SS due to several reasons.Thus,the clinical presentation(onset,severity,and clinical features)in such instances may not exactly match what toxicologists or psychiatrists observe in their respective settings.They produce considerable diversity in many aspects of SS.However,other experts discount these new developments in SS.Since SS is a potentially lethal illness,consensus is required on several concerns related to SS.

Lactate:a prospective target for therapeutic intervention in psychiatric disease

Although antipsychotics that act via monoaminergic neurotransmitter modulation have considera ble therapeutic effect,they cannot completely relieve clinical symptoms in patients suffering from psychiatric disorde rs.This may be attributed to the limited range of neurotransmitters that are regulated by psychotropic drugs.Recent findings indicate the need for investigation of psychotropic medications that target less-studied neurotransmitte rs.Among these candidate neurotransmitters,lactate is developing from being a waste metabolite to a glial-neuronal signaling molecule in recent years.Previous studies have suggested that cerebral lactate levels change considerably in numerous psychiatric illnesses;animal experiments have also shown that the supply of exogenous la ctate exerts an antidepressant effect.In this review,we have described how medications targeting newer neurotransmitte rs offer promise in psychiatric diseases;we have also summarized the advances in the use of lactate(and its corresponding signaling pathways)as a signaling molecule.In addition,we have described the alterations in brain lactate levels in depression,anxiety,bipolar disorder,and schizophrenia and have indicated the challenges that need to be overcome before brain lactate can be used as a therapeutic target in psychopharmacology.

Can acupuncture enhance therapeutic effectiveness of antidepressants and reduce adverse drug reactions in patients with depression? A systematic review and meta-analysis

Background: Some depressed patients receive acupuncture as an adjunct to their conventional medications.Objective: This review aims to provide evidence on whether acupuncture can enhance the therapeutic effectiveness of antidepressants for treating depression, and explore whether acupuncture can reduce the adverse reactions associated with antidepressants.Search strategy: English and Chinese databases were searched for randomized controlled trials(RCTs)published until December 1, 2021.Inclusion criteria: RCTs with a modified Jadad scale score ≥ 4 were included if they compared a group of participants with depression that received acupuncture combined with antidepressants with a control group that received antidepressants alone.Data extraction and analysis: Meta-analysis was performed, and statistical heterogeneity was assessed based on Cochran’s Q statistic and its related P-value. Primary outcomes were the reduction in the severity of depression and adverse reactions associated with antidepressants, while secondary outcomes included remission rate, treatment response, social functioning, and change in antidepressant dose.The Grading of Recommendations Assessment, Development and Evaluation(GRADE) framework was used to evaluate the overall quality of evidence in the included studies.Results: This review included 16 studies(with a total of 1958 participants). Most studies were at high risk of performance bias and at low or unclear risk of selection bias, detection bias, attrition bias, reporting bias, and other bias. Analysis of the 16 RCTs showed that, compared with antidepressants alone, acupuncture along with antidepressants reduced the Hamilton Depression Rating Scale-17(HAMD-17) scores(standard mean difference [SMD]-0.44, 95% confidence interval [CI]-0.55 to-0.33, P < 0.01;I^(2)= 14%), Self-rating Depression Scale(SDS) scores(SMD-0.53, 95% CI-0.84 to-0.23, P < 0.01;I^(2)= 79%), and the Side Effect Rating Scale(SERS) scores(SMD-1.11, 95% CI-1.56 to-0.66, P < 0.01;I^(2)= 89%). Compared with antidepressants alone, acupuncture along with antidepressants improved World Health Organization Quality of Life-BREF scores(SMD 0.31, 95% CI 0.18 to 0.44, P < 0.01;I^(2)= 15%), decreased the number of participants who increased their antidepressant dosages(relative risk[RR] 0.32, 95% CI 0.22 to 0.48, P < 0.01;I^(2)= 0%), and resulted in significantly higher remission rates(RR1.52, 95% CI 1.26 to 1.83, P < 0.01;I^(2)= 0%) and treatment responses(RR 1.35, 95% CI 1.24 to 1.47, P < 0.01;I^(2)= 19%) in terms of HAMD-17 scores. The HAMD-17, SDS and SERS scores were assessed as low quality by GRADE and the other indices as being of moderate quality.Conclusion: Acupuncture as an adjunct to antidepressants may enhance the therapeutic effectiveness and reduce the adverse drug reactions in patients receiving antidepressants. These findings must be interpreted with caution, as the evidence was of low or moderate quality and there was a lack of comparative data with a placebo control.Systematic review registration: INPLASY202150008.

On the Eve of Upgrading Antidepressants:(R)-Ketamine and Its Metabolites

Ketamine is a noncompetitive N-methyl-D-aspartate receptor （NMDAR） antagonist that has attracted wide- spread attention for its rapid-onset antidepressant effects, especially in individuals with treatment-resistant depres- sion and suicidal ideation [1-3]. Compared with the tra- ditional antidepressants that take weeks, if not months, to benefit patients and are associated with a high rate of relapse, ketamine exerts its antidepressant effects within several hours. These clinical benefits can last for 2 weeks after a single injection [1, 2, 4]. However, ketamine still has limited clinical application, psychotomimetic side-effects and liability of abuse. A recent paper in Nature [5] showed that the ketamine metabolite enantiomer （2R,6R）-hydroxynorketamine （HNK） has rapid and sustained antidepressant effects without the side-effects associated with ketamine, such as abuse potential. The discovery of （R）-ketamine is a land- mark in the field of depression. Investigations of its mechanism of action will inspire the development of a new

Food-derived protein hydrolysates and peptides:anxiolytic and antidepressant activities,characteristics,and mechanisms

Globally,the prevalence of anxiety and depression has reached epidemic proportions.Food-derived protein hydrolysates and peptides delivered through dietary supplementation can avoid the negative risks associated with traditional pharmaceuticals while delivering superior anxiolytic and antidepressant effects.This review summarizes current research on food-derived anxiolytic and antidepressant protein hydrolysates and peptides,and subsequently analyses their physicochemical characteristics and elaborates on their mechanisms.The aim of this work is to contribute to the in-depth study and provide a theoretical foundation for the development of related products to better serve patients with anxiety and depression.

Hypidone hydrochloride(YL-0919)ameliorates functional deficits after traumatic brain injury in mice by activating the sigma-1 receptor for antioxidation

Traumatic brain injury involves complex pathophysiological mechanisms,among which oxidative stress significantly contributes to the occurrence of secondary injury.In this study,we evaluated hypidone hydrochloride(YL-0919),a self-developed antidepressant with selective sigma-1 receptor agonist properties,and its associated mechanisms and targets in traumatic brain injury.Behavioral experiments to assess functional deficits were followed by assessment of neuronal damage through histological analyses and examination of blood-brain barrier permeability and brain edema.Next,we investigated the antioxidative effects of YL-0919 by assessing the levels of traditional markers of oxidative stress in vivo in mice and in vitro in HT22 cells.Finally,the targeted action of YL-0919 was verified by employing a sigma-1 receptor antagonist(BD-1047).Our findings demonstrated that YL-0919 markedly improved deficits in motor function and spatial cognition on day 3 post traumatic brain injury,while also decreasing neuronal mortality and reversing blood-brain barrier disruption and brain edema.Furthermore,YL-0919 effectively combated oxidative stress both in vivo and in vitro.The protective effects of YL-0919 were partially inhibited by BD-1047.These results indicated that YL-0919 relieved impairments in motor and spatial cognition by restraining oxidative stress,a neuroprotective effect that was partially reversed by the sigma-1 receptor antagonist BD-1047.YL-0919 may have potential as a new treatment for traumatic brain injury.

Association between 5-HTR1A gene C-1019G polymorphism and antidepressant response in patients with major depressive disorder:A meta-analysis

BACKGROUND Major depressive disorder(MDD)is a substantial global health concern,and its treatment is complicated by the variability in individual response to antide-pressants.AIM To consolidate research and clarify the impact of genetic variation on MDD treatment outcomes.METHODS Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines,a systematic search across PubMed,EMBASE,Web of Science,and the Cochrane Library was conducted without date restrictions,utilizing key terms related to MDD,serotonin 1A receptor polymorphism(5-HTR1A),C-1019G polymorphism,and antidepressant response.Studies meeting inclusion criteria were thoroughly screened,and quality assessed using the Newcastle-Ottawa Scale.Statistical analyses,includingχ2 and I²values,were used to evaluate heterogeneity and fixed-effect or random-effect models were applied accordingly.RESULTS The initial search yielded 1216 articles,with 11 studies meeting criteria for inclusion.Analysis of various genetic models showed no significant association between the 5-HTR1A C-1019G polymorphism and antidepressant efficacy.The heterogeneity was low to moderate,and no publication bias was detected through funnel plot symmetry and Egger's and Begg's tests.CONCLUSION This meta-analysis does not support a significant association between the 5-HTR1A C-1019G polymorphism and the efficacy of antidepressant treatment in MDD.The findings call for further research with larger cohorts to substantiate these results and enhance the understanding of antidepressant pharmacogenetics.

Intranasal delivery of rapid-onset antidepressants:a new trend of treating major depressive disorder

Existing antidepressants seem to have an onset time of several weeks.However,newly found depression-related receptors and pathways may enlighten us to find more rapid-onset antidepressants,in which ketamine is one of the most potential antidepressants.By intranasal administration,drugs can be directly delivered to the brain via olfactory nerve route,which is proved to be suitable for some antidepressants.Well-designed rapid-onset antidepressants are the urgent requirements of the patients with depression.Intranasal administration,as a potential strategy to deliver antidepressants to brain,can improve drug efficacy and largely shorten the onset time.In this article,we sorted out some new formulation approaches in treating depression with different mechanisms and pathways compared with traditional treating strategies,along with new findings in clinical studies,proving that the combination of rapid-onset antidepressants with intranasal delivery will lead a new trend in treating depression.

Rapid-acting antidepressants targeting K2P(TREK1) channel

With the support of the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Yang Huaiyu(阳怀宇)from the East China Normal University and Prof.Li Yang(李扬)from Shanghai Institute of Materia Medica,Chinese Academy of Sciences

Agomelatine:a potential novel approach for the treatment of memory disorder in neurodegenerative disease

Agomelatine is a selective agonist of melatonin receptor 1A/melatonin receptor 1B(MT/MT)and antagonist of 5-hydroxytryptamine 2C receptors.It is used clinically to treat major depressive episodes in adults.The pro-chronobiological activity of agomelatine reconstructs sleep-wake rhythms and normalizes circadian disturbances via its agonistic effect of melatonin receptor 1A/melatonin receptor 1B,which work simultaneously to counteract depression and anxiety disorder.Moreover,by antagonizing neocortical postsynaptic 5-hydroxytryptamine 2C receptors,agomelatine enhances the release of dopamine and noradrenaline in the prefrontal cortex,increases the activity of dopamine and noradrenaline,and thereby reduces depression and anxiety disorder.The combination of these two effects means that agomelatine exhibits a unique pharmacological role in the treatment of depression,anxiety,and disturbance of the circadian rhythm.Emotion and sleep are closely related to memory and cognitive function.Memory disorder is defined as any forms of memory abnormality,which is typically evident in a broad range of neurodegenerative diseases,including Alzheimer’s disease.Memory impairment and cognitive impairment are common symptoms of neurodegenerative and psychiatric diseases.Therefore,whether agomelatine can improve memory and cognitive behaviors if used for alleviating depression and circadian-rhythm sleep disorders has become a research“hotspot”.This review presents the latest findings on the effects of agomelatine in the treatment of psychologic and circadian-rhythm sleep disorders in clinical trials and animal experiments.Our review evaluates recent studies on treatment of memory impairment and cognitive impairment in neurodegenerative and psychiatric diseases.