Rapid-acting antidepressant ketamine, its metabolites and other candidates: A historical overview and future perspective

Plasma esketamine and noresketamine levels and antidepressant response with oral esketamine treatment

OBJECTIVE

Oral esketamine has relatively low and variable bioavailability, which may complicate broader use as an antidepressant. This study aimed to investigate associations between different pharmacokinetic outcomes and change in depressive symptoms following oral esketamine administration in patients with treatment-resistant depression. Understanding such associations may inform dosing and administration strategies in clinical practice.

METHODS

Oral esketamine was administered twice weekly for six weeks using a titration approach in 17 patients. Esketamine and noresketamine serum levels were measured 30 min and 60 min after esketamine administration. Change in depression severity was plotted against the serum levels of esketamine and noresketamine, their sum and their ratios.

RESULTS

We observed high inter-individual variability in oral esketamine pharmacokinetics, and we found no association between depressive symptom change and the pharmacokinetic outcomes. The small sample size and flexible-dose regimen complicate definitive conclusions.

DISCUSSION

In the treatment of depression, clinical response may not correspond to esketamine pharmacokinetic outcomes. Individually-based titration strategies based on clinical antidepressant effects appear to be the optimal approach moving forward.

Drug-related suicidal ideation in the K-12 population: a real-world pharmacovigilance study of the FDA adverse event reporting system (FAERS) database

OBJECTIVE

The K-12 population refers to individuals, primarily aged 6-17, from kindergarten through 12th grade. Drug-related suicidal ideation (SI) in the K-12 population is a major concern. This study aims to identify medications linked to increased SI risk in the K-12 population using the FDA Adverse Event Reporting System (FAERS) database.

METHODS

We extracted cases of SI in individuals aged 6-17 years where medications were the primary suspect (PS) from the FAERS database, spanning from the first quarter of 2004 to the third quarter of 2023. We conducted descriptive analysis, disproportionality analysis, and subgroup analysis.

RESULTS

Our analysis included 4,779 valid cases; 52.75 % were male and 45.66 % were female. The predominant age group was 15-17 years, accounting for 43.92 % of cases. The peak year for case reports was 2019. Montelukast was the most common drug. The four most common indications included attention deficit hyperactivity disorder, depression, acne, and asthma. Disproportionality analysis highlighted 21 drugs as potentially associated with increased SI risk, with esketamine displaying the highest signal (Reporting Odds Ratio, ROR = 103.49). Subgroup analysis identified eleven drugs with elevated risk signals in both genders. Montelukast presented the highest signal in males (ROR = 12.64), and esketamine in females (ROR = 129.50). Cumulatively, the incidence of SI within 90 and 360 days was 51.6 % and 76.9 % in males, and 58.8 % and 85.3 % in females, respectively.

CONCLUSION

This study provides evidence of potential SI risk associated with specific medications in the K-12 population. Further research is necessary to confirm these findings.

Demyelination in psychiatric and neurological disorders: Mechanisms, clinical impact, and novel therapeutic strategies

Demyelination, defined as the loss of myelin sheaths around neuronal axons, is increasingly recognized as a key factor in a broad range of psychiatric and neurological disorders, including schizophrenia, major depressive disorder, bipolar disorder, post-traumatic stress disorder, autism spectrum disorder, substance use disorders, Alzheimer's disease, Parkinson's disease, and multiple sclerosis. This review investigates the core mechanisms driving demyelination, its clinical impact, and emerging therapeutic strategies aimed at maintaining or restoring myelin integrity. Disruption of myelin impairs crucial neural communication pathways, resulting in cognitive, motor, and behavioral deficits that substantially reduce quality of life and create significant economic and social challenges. Key contributors to demyelination include genetic predisposition, environmental triggers, immune dysregulation, neuroinflammation, and alterations in the gut-brain axis mediated by the vagus nerve. Promising therapies include sphingosine 1-phosphate receptor modulators and muscarinic acetylcholine receptor antagonists, both of which diminish immune-related myelin damage and may enhance neuroprotection. In addition, the novel antidepressant arketamine appears to boost myelination through transforming growth factor-β1 signaling pathways. Approaches targeting the gut-brain axis, such as noninvasive transcutaneous auricular vagus nerve stimulation and fecal microbiota transplantation, may also help reduce inflammation and support myelin repair. Future research should center on clarifying the precise molecular mechanisms of demyelination, developing targeted therapies, and leveraging advanced neuroimaging for earlier detection and personalized treatment. By combining immunomodulatory and neuroprotective strategies, there is potential to significantly improve outcomes for individuals affected by demyelinating psychiatric and neurological disorders.

Safety considerations and risk mitigation strategies for ketamine use: a comprehensive review

Ketamine, a dissociative anesthetic, has gained widespread use in various medical contexts, including anesthesia, pain management, and treatment-resistant depression. Despite its therapeutic potential, concerns regarding its safety profile have prompted ongoing research and regulatory guidance. This comprehensive literature review explores the current safety considerations of ketamine, summarizing its adverse effects, particularly on cardiovascular, neuropsychiatric, and dependency effects. Evidence-based guidelines for its administration, dosing, and monitoring are discussed, emphasizing the importance of risk-benefit assessments in clinical practice. The review also delves into current guidelines and proposes future directions for ketamine research and clinical implementation, including enhanced safety protocols, long-term patient outcomes, and the development of individualized safe dosing protocols.

Repeated administration of esketamine ameliorates mechanical allodynia in mice with chemotherapy-induced peripheral neuropathy: A role of gut microbiota and metabolites

Chemotherapy-induced peripheral neuropathy (CIPN) severely diminishes the quality of life for cancer survivors, yet effective treatments remain scarce. Esketamine, a commonly used anesthetic, has demonstrated neuroprotective effects by restoring gut microbiome dysbiosis. In this study, we investigated the impact of esketamine on nociceptive sensitivity in a mouse model of CIPN and explored the potential involvement of the gut microbiome. In mice treated with oxaliplatin, repeated esketamine doses (in contrast to a single dose) significantly improved the paw withdrawal threshold (PWT). Western blot and qPCR analyses further revealed that repeated esketamine administration markedly reduced microglial activation and neuroinflammation in the dorsal root ganglion (DRG), underscoring its potent anti-inflammatory properties. Moreover, fecal 16S rRNA analysis indicated that esketamine partially restored the abnormal gut microbiota composition (β-diversity). Plasma metabolome analysis showed that repeated esketamine treatment significantly lowered the elevated levels of 6H-indolo[2,3-b]quinoline and restored the reduced levels of (3-exo)-3-[3-methyl-5-(1-methylethyl)-4H-1,2,4-triazol-4-yl]-8-azabicyclo[3.2.1]octane observed in oxaliplatin-treated mice. In addition, fecal microbiota transplantation from esketamine-treated CIPN mice notably improved both the diminished PWT and DRG neuroinflammation in oxaliplatin-treated mice. Collectively, these findings suggest that repeated esketamine administration may alleviate mechanical allodynia in CIPN mice by modulating neuroinflammation, gut microbiota, and associated metabolites.

Adjunctive ketamine vs. buprenorphine in co-occurring major depressive disorder and opioid use disorder: a randomized, double-blind clinical trial assessing anxiety symptom severity and craving intensity

BACKGROUND

The concomitant presence of major depressive disorder (MDD) and opioid use disorder (OUD) poses a formidable clinical challenge, warranting effective interventions that address both psychiatric and addictive components.

AIMS

This study sought to compare the efficacy of adjunctive ketamine and buprenorphine in mitigating anxiety symptom severity and craving intensity in individuals with co-occurring MDD and OUD.

METHODS

A randomized, double-blind clinical trial was conducted, involving individuals meeting diagnostic criteria for both MDD and OUD. Participants were randomly assigned to receive adjunctive ketamine or buprenorphine, in conjunction with standard psychiatric and addiction treatments. Anxiety symptom severity and craving intensity were assessed using Hamilton Anxiety Rating Scale (HAM-A), and the Opioid Craving Scale after 2 h, 24 h, and 7 days.

RESULTS

The findings revealed distinct treatment trajectories, with ketamine demonstrating rapid and substantial reduction in anxiety symptom severity within hours of administration, accompanied by a pronounced decline in opioid craving intensity. In contrast, buprenorphine was associated with a more gradual but sustained improvement in anxiety symptoms over several days, paralleled by a modest initial reduction in opioid craving, followed by persistent attenuation.

CONCLUSIONS

In conclusion, this randomized clinical trial provides evidence supporting the efficacy of adjunctive Ketamine and Buprenorphine in reducing anxiety symptoms and craving intensity in patients with co-occurring MDD and OUD.

TRIAL REGISTRATION

IRCT20211214053411N1.

Esketamine alleviates LPS-induced depression-like behavior by activating Nrf2-mediated anti-inflammatory response in adolescent mice

BACKGROUND

The mechanisms underlying esketamine's therapeutic effects remain elusive. The study aimed to explore the impact of single esketamine treatment on LPS-induced adolescent depressive-like behaviors and the role of Nrf2 regulated neuroinflammatory response in esketamine-produced rapid antidepressant efficacy.

METHODS

Adolescent male C57BL/6J mice were randomly assigned to three groups: control, LPS, and LPS + esketamine (15 mg/kg, i.p.). Depressive-like behaviors were evaluated via the OFT, NFST, and TST. Protein expression of Nrf2 and inflammatory cytokines, including TNF-α, IL-1β, and iNOS in the hippocampus and mPFC, were measured by western blot. Moreover, the Nrf2 inhibitor, ML385, was also applied in the current study. The depressive-like behaviors and the protein expression of Nrf2, TNF-α, IL-1β, and iNOS in mPFC and hippocampus were also measured. Additionally, the plasma's pro-inflammatory cytokines and anti-inflammatory cytokines were assessed using ELISA methods with or without ML385.

RESULTS

A single administration of esketamine treatment alleviated the LPS-induced depressive-like behaviors. Esketamine increased the expression of Nrf2 and reduced the expression of the inflammatory cytokines, including TNF-α, IL-1β, and iNOS, in the mPFC and hippocampus. Notably, pharmacological inhibition of Nrf2 via ML385 administration abrogated the antidepressive-like behaviors and anti-inflammatory effects induced by esketamine. In the periphery, esketamine mitigated the LPS-induced elevation of pro-inflammatory cytokines, and the reduction of anti-inflammatory cytokines, and this effect was reversed by Nrf2 inhibition.

CONCLUSION

Esketamine treatment exerts rapid antidepressant effects and attenuates neuroinflammation in LPS-induced adolescent depressive-like behaviors, potentially through the activation of Nrf2-mediated anti-inflammatory signaling.

The brain, rapid eye movement sleep, and major depressive disorder: A multimodal neuroimaging study

BACKGROUND

Evidence has established the prominent involvement of rapid eye movement (REM) sleep disturbance in major depressive disorder (MDD). However, the neural correlates of REM sleep in MDD and their clinical significance are less clear.

METHODS

Cross-sectional and longitudinal polysomnography and resting-state functional MRI data were collected from 131 MDD patients and 71 healthy controls to measure REM sleep and voxel-mirrored homotopic connectivity (VMHC). Correlation and mediation analyses were performed to examine the associations between REM sleep, VMHC, and clinical variables. Moreover, we conducted spatial correlations between the neural correlates of REM sleep and a multimodal collection of reference brain maps to facilitate genetic, structural and functional annotations.

RESULTS

MDD patients exhibited REM sleep abnormalities manifesting as higher REM sleep latency and lower REM sleep duration, which were correlated with decreased VMHC of the precentral gyrus and inferior parietal lobe and mediated their associations with more severe anxiety symptoms. Longitudinal data showed that VMHC increase of the inferior parietal lobe was related to improvement of depression symptoms in MDD patients. Spatial correlation analyses revealed that the neural correlates of REM sleep in MDD were linked to gene categories primarily involving cellular metabolic process, signal pathway, and ion channel activity as well as linked to cortical microstructure, metabolism, electrophysiology, and cannabinoid receptor.

CONCLUSION

These findings may add important context to the growing literature on the complex interplay between sleep and MDD, and more broadly may inform future treatment for depression via regulating sleep.

Arketamine alleviates cognitive impairments and demyelination in mice with postoperative cognitive dysfunction via TGF-β1 activation

Postoperative cognitive dysfunction (POCD) is characterized by a decline in cognitive functions, including memory, attention, and executive abilities, following surgery, with no effective therapeutic drugs currently available. Arketamine, the (R)-enantiomer of ketamine, has shown promise in mitigating cognitive deficits in animal models. In this study, we investigated whether arketamine could ameliorate cognitive deficits in a mouse model of POCD, with a focus on the role of transforming growth factor (TGF)-β1 in its effects. POCD mice displayed cognitive impairments and demyelination in the corpus callosum. A single arketamine injection (10 mg/kg) significantly improved both cognitive function and demyelination in the corpus callosum of POCD mice. Notably, pretreatment with RepSox (10 mg/kg), a TGF-β receptor 1 inhibitor, significantly blocked the beneficial effects of arketamine on cognitive deficits and demyelination. Moreover, intranasal administration of TGF-β1 (3.0 μg/kg) markedly alleviated cognitive impairments and demyelination in POCD mice. These findings suggest that arketamine exerts its effects through a TGF-β1-dependent mechanism, positioning it as a potential therapeutic option for POCD.

Differed spontaneous dissociative symptoms following the use of esketamine intranasal spray in a patient suffering from treatment-resistant depression: a case report

Intranasal esketamine is used in France for treatment-resistant depression. Dissociative symptoms are common side effects during treatment sessions. We report a case of delayed spontaneous dissociative symptoms following esketamine administration. A 20-year-old female with treatment-resistant depression received esketamine treatment. Dissociative symptoms occurred during sessions and persisted at a distance, often accompanied by anxiety. Delayed dissociative phenomena disappeared within the fourth week of treatment by esketamine. The literature mainly discusses dissociation during esketamine treatment sessions, with limited data on differed spontaneous episodes. Three hypotheses are discussed concerning the mechanism of occurrence of these dissociative phenomena, including esketamine's direct effect, central nervous system sensitization, and anxiety-induced dissociation. We present the first case of differed spontaneous dissociative effects after intranasal esketamine administration for treatment-resistant depression. Our main hypothesis suggests that esketamine may act as a 'pattern' for dissociative experiences, heightening the patient's ability to discern these phenomena during other instances of dissociation, such as acute anxiety attacks. Further research is needed to validate this hypothesis.

The Use of Classic Psychedelics for Depressive and Anxiety-Spectrum Disorders: A Comprehensive Review

ABSTRACT

Following a decades-long decline in psychedelic research resulting from social, political, and legislative factors, there has been greatly renewed interest in these compounds' ability to treat psychiatric disorders. Classic psychedelics, encompassing both natural and synthetic psychoactive compounds, are characterized by their action as agonists or partial agonists of serotonin 5-hydroxytryptamine 2A receptors. In this comprehensive review, we summarize the latest clinical trials of classic psychedelics on depression and anxiety, attending to the patient demographics and methodology of each study. Overall, studies published since 2020 affirm the potential for classic psychedelics to treat major depressive disorder, treatment-resistant depression, bipolar II, and anxiety-spectrum disorders. However, findings are limited by short follow-up durations and nonstandard dosing and study designs. Given that many of the studies identified were post hoc analyses or follow-up studies from a select few parent studies, it is recommended that more original research be undertaken, with more diverse and larger sample sizes, standardized methodologies including blinding assessment, and long-term follow-up to identify duration of benefits and adverse reactions. It is also important to consider the role of psychological support and the therapeutic alliance in the psychedelic treatment of psychiatric disorders.

Effects of psychedelics on neurogenesis and broader neuroplasticity: a systematic review

In the mammalian brain, new neurons continue to be generated throughout life in a process known as adult neurogenesis. The role of adult-generated neurons has been broadly studied across laboratories, and mounting evidence suggests a strong link to the HPA axis and concomitant dysregulations in patients diagnosed with mood disorders. Psychedelic compounds, such as phenethylamines, tryptamines, cannabinoids, and a variety of ever-growing chemical categories, have emerged as therapeutic options for neuropsychiatric disorders, while numerous reports link their effects to increased adult neurogenesis. In this systematic review, we examine studies assessing neurogenesis or other neurogenesis-associated brain plasticity after psychedelic interventions and aim to provide a comprehensive picture of how this vast category of compounds regulates the generation of new neurons. We conducted a literature search on PubMed and Science Direct databases, considering all articles published until January 31, 2023, and selected articles containing both the words "neurogenesis" and "psychedelics". We analyzed experimental studies using either in vivo or in vitro models, employing classical or atypical psychedelics at all ontogenetic windows, as well as human studies referring to neurogenesis-associated plasticity. Our findings were divided into five main categories of psychedelics: CB1 agonists, NMDA antagonists, harmala alkaloids, tryptamines, and entactogens. We described the outcomes of neurogenesis assessments and investigated related results on the effects of psychedelics on brain plasticity and behavior within our sample. In summary, this review presents an extensive study into how different psychedelics may affect the birth of new neurons and other brain-related processes. Such knowledge may be valuable for future research on novel therapeutic strategies for neuropsychiatric disorders.

LT-102, an AMPA receptor potentiator, alleviates depression-like behavior and synaptic plasticity impairments in prefrontal cortex induced by sleep deprivation

BACKGROUND

Sleep loss is closely related to the onset and development of depression, and the mechanisms involved may include impaired synaptic plasticity. Considering the important role of glutamate α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) in synaptic plasticity as well as depression, we introduce LT-102, a novel AMPARs potentiator, to evaluate the potential of LT-102 in treating sleep deprivation-induced depression-like behaviors.

METHODS

We conducted a comprehensive behavioral assessment to evaluate the effects of LT-102 on depression-like symptoms in male C57BL/6J mice. This assessment included the open field test to measure general locomotor activity and anxiety-like behavior, the forced swimming test and tail suspension test to assess despair behaviors indicative of depressive states, and the sucrose preference test to quantify anhedonia, a core symptom of depression. Furthermore, to explore the impact of LT-102 on synaptic plasticity, we utilized a combination of Western blot analysis to detect protein expression levels, Golgi-Cox staining to visualize neuronal morphology, and immunofluorescence to examine the localization of synaptic proteins. Additionally, we utilized primary cortical neurons to delineate the signaling pathway modulated by LT-102.

RESULTS

Treatment with LT-102 significantly reduced depression-like behaviors associated with sleep deprivation. Quantitative Western blot (WB) analysis revealed a significant increase in GluA1 phosphorylation in the prefrontal cortex (PFC), triggering the Ca2+/calmodulin-dependent protein kinase II/cAMP response element-binding protein/brain-derived neurotrophic factor (CaMKII/CREB/BDNF) and forkhead box protein P2/postsynaptic density protein 95 (FoxP2/PSD95) signaling pathways. Immunofluorescence imaging confirmed that LT-102 treatment increased spine density and co-labeling of PSD95 and vesicular glutamate transporter 1 (VGLUT1) in the PFC, reversing the reductions typically observed following sleep deprivation. Golgi staining further validated these results, showing a substantial increase in neuronal dendritic spine density in sleep-deprived mice treated with LT-102. Mechanistically, application of LT-102 to primary cortical neurons, resulted in elevated levels of phosphorylated AKT (p-AKT) and phosphorylated glycogen synthase kinase-3 beta (p-GSK3β), key downstream molecules in the BDNF signaling pathway, which in turn upregulated FoxP2 and PSD95 expression.

LIMITATIONS

In our study, we chose to exclusively use male mice to eliminate potential influences of the estrous cycle on behavior and physiology. As there is no widely accepted positive drug control for sleep deprivation studies, we did not include one in our research.

CONCLUSION

Our results suggest that LT-102 is a promising therapeutic agent for counteracting depression-like behaviors and synaptic plasticity deficits induced by sleep deprivation, primarily through the activation of CaMKII/CREB/BDNF and AKT/GSK3β/FoxP2/PSD95 signaling pathways.

Effects of arketamine on depression-like behaviors and demyelination in mice exposed to chronic restrain stress: A role of transforming growth factor-β1

BACKGROUND

Chronic restrain stress (CRS) induces depression-like behaviors and demyelination in the brain; however, the relationship between these depression-like behaviors and demyelination remains unclear. Arketamine, the (R)-enantiomer of ketamine, has shown rapid antidepressant-like effects in CRS-exposed mice.

METHODS

We examined whether arketamine can improve both depression-like behaviors and demyelination in the brains of CRS-exposed mice. Additionally, we investigated the role of transforming growth factor β1 (TGF-β1) in the beneficial effects of arketamine.

RESULTS

A single dose of arketamine (10 mg/kg) improved both depression-like behavior and demyelination in the corpus callosum of CRS-exposed mice. Correlations were found between depression-like behaviors and demyelination in this region. Furthermore, pretreatment with RepSox, an inhibitor of TGF-β1 receptor, significantly blocked the beneficial effects of arketamine on depression-like behaviors and demyelination in CRS-exposed mice. Finally, a single intranasal administration of TGF-β1 ameliorated both depression-like behaviors and demyelination in CRS-exposed mice.

LIMITATIONS

The precise mechanisms by which TGF-β1 contributes to the effects of arketamine remain unclear.

CONCLUSIONS

These data suggest that CRS-induced demyelination in the corpus callosum may contribute to depression-like behaviors, and that arketamine can mitigate these changes through a TGF-β1-dependent mechanism.

Transforming growth factor-β1 mediates the beneficial effects of arketamine on demyelination and remyelination in the brains of cuprizone-treated mice

The novel antidepressant arketamine, the (R)-enantiomer of ketamine, has been shown to ameliorate demyelination and facilitate remyelination in the brains of cuprizone (CPZ)-treated mice. However, the mechanisms behind its effects remain unclear. Given the role of transforming growth factor β1 (TGF-β1) in arketamine's antidepressant-like effects, we examined whether TGF-β1 also plays a role in arketamine's effects on demyelination and remyelination in CPZ-treated mice. Additionally, we investigated the effects of intranasal TGF-β1 on demyelination and remyelination in these mice. Repeated intermittent administration of arketamine (10 mg/kg/day, twice weekly for the last 2-weeks) attenuated demyelination in the corpus callosum (CC) of CPZ (6 weeks)-treated mice. Furthermore, pretreatment with RepSox (10 mg/kg/day), an inhibitor of the TGF-β receptor 1, significantly blocked the beneficial effects of arketamine on the demyelination in the CC of CPZ-treated mice. Additionally, repeated intermittent administration of TGF-β1 (3.0 μg/kg/day, twice weekly for 2 weeks) significantly ameliorated demyelination and facilitated remyelination in the CC of CPZ-treated mice. These data suggest that arketamine can mitigate demyelination and facilitates remyelination in the brains of CPZ-treated mice through a TGF-β1-dependent mechanism.

Splenic γδ T cells mediate antidepressant and prophylactic actions of arketamine in lipopolysaccharide-induced depression in mice

Arketamine, the (R)-enantiomer of ketamine, exhibits both therapeutic and sustained prophylactic effects in an inflammation-driven model of depression, although the precise mechanisms remain elusive. Given the involvement of γδ T cells in inflammatory processes, this study explored their role in the effects of arketamine. To assess therapeutic outcomes, mice received lipopolysaccharide (LPS:1.0 mg/kg), followed by either arketamine (10 mg/kg) or saline. For prophylactic assessment, arketamine or saline was administered six days prior to LPS exposure. A single dose of LPS (1.0 mg/kg) reduced the proportion of γδ T cells in the spleen but did not affect their levels in the blood, prefrontal cortex, or small intestine. Arketamine mitigated LPS-induced splenomegaly, counteracted the elevation of plasma interleukin-6 levels and the reduction in the proportion of splenic γδ T cells, and alleviated depression-like behavior as assessed by the forced swimming test. Notably, negative correlations were observed between the proportion of splenic γδ T cells and indicators of inflammation and depression. Furthermore, pretreatment with a γδ TCR antibody significantly countered the therapeutic and prophylactic effects of arketamine on LPS-induced changes. These findings highlight a novel role for splenic γδ T cells in inflammation-associated depression and suggest the potential of arketamine as a treatment option. Consequently, γδ T cells may represent a novel therapeutic target for inflammation-related depression. Further studies on the role of γδ T cells in depressed patients with inflammation are warranted.

Perioperative administration of sub-anesthetic ketamine/esketamine for preventing postpartum depression symptoms: A trial sequential meta-analysis

OBJECTIVE

Postpartum depression (PPD) is a major mental health issue affecting 10%-15% of women globally. This meta-analysis synthesized updated evidence on sub-anesthetic ketamine/esketamine's efficacy in preventing PPD.

METHODS

Randomized controlled trials (RCTs) comparing ketamine/esketamine to a placebo for PPD prevention were searched without language restriction. Primary outcomes were PPD risk at 1- and 4-6-week postpartum. Secondary outcomes included the difference in depression scores and risk of adverse events. Trial sequential analysis (TSA) was conducted to validate the reliability.

RESULTS

A meta-analysis of 22 RCTs (n = 3,463) showed that ketamine/esketamine significantly decreased PPD risk at 1- (risk ratio [RR], 0.41; 95% confidence interval [CI], 0.3-0.57) and 4-6-week (RR, 0.47; 95%CI, 0.35-0.63) follow-ups. Consistently, participants receiving ketamine/esketamine had lower depression-related scores at 1- (standardized mean difference [SMD], -0.94; 95%CI, -1.26 to -0.62) and 4-6-week (SMD, -0.89; 95%CI, -1.25 to -0.53) follow-ups. Despite potential publication bias, TSA confirmed the evidence's reliability. Subgroup analysis showed that ketamine/esketamine's preventive effect on 1-week PPD was consistent, regardless of administration timing, type of agents, or total dosage (<0.5 vs. ≥0.5 mg/kg). For the 4-6-week period, PPD risk was favorably reduced only with postoperative administration or the use of esketamine, with the total dosage having no observed influence. Participants on ketamine/esketamine experienced more frequency of hallucinations (RR, 4.77; 95%CI, 1.39-16.44) and dizziness (RR, 1.36; 95%CI, 1.02-1.81).

CONCLUSION

Our findings advocate for the postoperative administration of low-dose ketamine/esketamine to avert PPD, which needed additional research for confirmation.

Ketamine attenuates kidney damage and depression-like behaviors in mice with cisplatin-induced acute kidney injury

Acute kidney injury (AKI) is a serious condition characterized by decreased urine output, often accompanied by psychiatric symptoms like depression. However, there are limited pharmacological treatments available for AKI and its associated depressive symptoms. In this study, we investigated whether cisplatin-induced AKI in mice leads to depression-like behaviors and whether ketamine could alleviate both the kidney injury and these behaviors. Mice with cisplatin-induced AKI exhibited elevated levels of creatinine and urea, kidney damage, increased kidney injury molecule-1 protein, and pathological changes in the liver, colon, and spleen. They also showed depression-like behaviors and reduced expression of synaptic proteins in the prefrontal cortex. Remarkably, a single dose of ketamine significantly reduced these symptoms and pathological changes. Interestingly, the beneficial effects of ketamine on the kidneys, other organs, and depression-like behaviors, were reversed by the tropomyosin receptor kinase B (TrkB) inhibitor ANA-12. Western blot analysis revealed the involvement of the TrkB and ERK (extracellular signal-regulated kinase)-CREB (cAMP response element binding protein) signaling pathway. Additionally, metabolomics analysis indicated that blood metabolites, such as C16-ceramide, may contribute to the effects of ketamine in this model. These findings suggest that cisplatin-induced nephrotoxicity in AKI mice contributes to depression-like behaviors, and ketamine can alleviate both kidney damage and depression-like symptoms by modulating the TrkB and ERK-CREB signaling pathways, as well as altering blood metabolites. However, the role of the kidney-brain axis in these depression-like behaviors remains unclear. Furthermore, ketamine may have therapeutic potential for treating kidney diseases such as AKI, along with associated depressive symptoms.

Glutamatergic Modulators for Major Depression from Theory to Clinical Use

Major depressive disorder (MDD) is a chronic, burdensome, highly prevalent disease that is characterized by depressed mood and anhedonia. MDD is especially burdensome as approved monoamine antidepressant treatments have weeks-long delays before clinical benefit and low remission rates. In the past 2 decades, a promising target emerged to improve patient outcomes in depression treatment: glutamatergic signaling. This narrative review provides a high-level overview of glutamate signaling in synaptogenesis and neural plasticity and the implications of glutamate dysregulation in depression. Based on this preclinical evidence implicating glutamate in depression and the rapid improvement of depression with ketamine treatment in a proof-of-concept trial, a range of N-methyl-D-aspartate (NMDA)-targeted therapies have been investigated. While an array of treatments has been investigated in registered phase 2 or 3 clinical trials, the development of most of these agents has been discontinued. Multiple glutamate-targeted antidepressants are actively in development, and two are approved. Nasal administration of esketamine (Spravato®) was approved by the US Food and Drug Administration (FDA) in 2019 to treat adults with treatment-resistant depression and in 2020 for adults with MDD with acute suicidal ideation or behavior. Oral combination dextromethorphan-bupropion (AXS-05, Auvelity® extended-release tablet) was FDA approved in 2022 for the treatment of MDD in adults. These approvals bolster the importance of glutamate in depression and represent an exciting breakthrough in contemporary psychiatry, providing new avenues of treatment for patients as first-line therapy or with either poor response or unacceptable side effects to monoaminergic antidepressants.

Is the antidepressant effect of ketamine separate from its psychotomimetic effect? A review of rodent models

Ketamine is an NMDA (N-methyl-d-aspartate) glutamate receptor antagonist, which has a myriad of dose-dependent pharmacological and behavioral effects, including anesthetic, sedative, amnestic, analgesic, and anti-inflammatory properties. Intriguingly, ketamine at subanesthetic doses displays a relevant profile both in mimicking symptoms of schizophrenia and also as the first fast-acting treatment for depression. Here, we present an overview of the state-of-the-art knowledge about ketamine as an antidepressant as well as a pharmacological model of schizophrenia in animal models and human participants. Ketamine's dual effect appears to arise from its mechanism of action involving NMDA receptors, with both immediate and downstream consequences being triggered as a result. Finally, we discuss the feasibility of a unified approach linking the glutamatergic hypothesis of schizophrenia to the promising preclinical and clinical success of ketamine in the treatment of refractory depression.

Therapeutic potential of ketamine in management of epilepsy: Clinical implications and mechanistic insights

Epilepsy, a widespread neurological disorder, affects approximately 50 million people worldwide. This disorder is typified by recurring seizures due to abnormal neuron communication in the brain. The seizures can lead to severe ischemia and hypoxia, potentially threatening patients' lives. However, with proper diagnosis and treatment, up to 70 % of patients can live without seizures. The causes of epilepsy are complex and multifactorial, encompassing genetic abnormalities, structural brain anomalies, ion channel dysfunctions, neurotransmitter imbalances, neuroinflammation, and immune system involvement. These factors collectively disrupt the crucial balance between excitation and inhibition within the brain, leading to epileptic seizures. The management of treatment-resistant epilepsy remains a considerable challenge, necessitating innovative therapeutic approaches. Among emerging potential treatments, ketamine-a drug traditionally employed for anesthesia and depression-has demonstrated efficacy in reducing seizures. It is noteworthy that, independent of its anti-epileptic effects, ketamine has been found to improve the balance between excitatory and inhibitory (E/I) activities in the brain. The balance is crucial for maintaining normal neural function, and its disruption is widely considered a key driver of epileptic seizures. By acting on N-methyl-D-aspartate (NMDA) receptors and other potential mechanisms, ketamine may regulate neuronal excitability, reduce excessive synchronized neural activity, and counteract epileptic seizures. This positive impact on E/I balance reinforces the potential of ketamine as a promising drug for treating epilepsy, especially in patients who are insensitive to traditional anti-epileptic drugs. This review aims to consolidate the current understanding of ketamine's therapeutic role in epilepsy. It will focus its impact on neuronal excitability and synaptic plasticity, its neuroprotective qualities, and elucidate the drug's potential mechanisms of action in treating epilepsy. By scrutinizing ketamine's impact and mechanisms in various types of epilepsy, we aspire to contribute to a more comprehensive and holistic approach to epilepsy management.

Efficacy of racemic ketamine or esketamine monotherapy for reducing suicidal ideation in uni- or bipolar depression: a systematic review and meta-analysis

The current systematic review and meta-analysis examined the effect of racemic ketamine or esketamine on suicidal ideation in individuals with uni- or bipolar depression. We searched the MEDLINE, Embase, Central, PsycINFO, and Web of Science databases to identify randomized controlled trials that examined the effect of racemic ketamine or esketamine monotherapy on suicidal ideation (SI) in individuals with uni- or bipolar depression. The two monotherapies were compared; the primary outcome was the rate of remission of SI, and the secondary outcome was the SI score. The risk ratio was used as an effect size measure for binary variables, while the standardized mean difference was used as an effect size measure for continuous variables. Our meta-analysis included 13 randomized controlled trials involving 1,1109 individuals with uni- or bipolar depression. Patients receiving racemic ketamine monotherapy had a significantly higher acute SI remission rate than those receiving placebo or midazolam (RR = 2.06, 95% CI 1.47 to 2.91, P < 0.0001). Racemic ketamine also led to significantly lower SI scores than placebo or midazolam (SMD = -0.36, 95% CI -0.71 to -0.01, P = 0.04). The evidence for the treatment of SI with esketamine was inconsistent. The pooled effect sizes for long-term anti-SI effects did not reveal significant differences between therapies. Our study indicated the efficacy of racemic ketamine monotherapy for rapidly and transiently reducing SI in individuals with uni- or bipolar depression, but the efficacy of racemic ketamine monotherapy against long-term suicidal ideation remains unclear. There is not -sufficient evidence to support the anti-suicidal effects of esketamine monotherapy.Protocol registration: Prospero registration number: CRD42023434380.

Effect of Esketamine on Postoperative Delirium in Patients Undergoing Cardiac Valve Replacement with Cardiopulmonary Bypass: A Randomized Controlled Trial

BACKGROUND

The aim of this study was to investigate the effects of esketamine on the risk of postoperative delirium (POD) in adults undergoing on-pump cardiac valve surgery.

METHODS

In this randomized, triple-blind, controlled trial, 116 adult patients with an American Society of Anesthesiologists (ASA) grade Ⅱ or Ⅲ and a New York Heart Association (NYHA) grade Ⅱ or Ⅲ who underwent cardiac valve surgery with cardiopulmonary bypass were included. Esketamine (0.25 mg/kg) or normal saline was administered intravenously before anesthesia induction. The primary outcome was POD, defined as a positive delirium assessment according to the 3-minute confusion assessment method (CAM) or the confusion assessment method for the intensive care unit (CAM-ICU) on a twice-daily basis for 7 days after surgery. Delirium duration and the delirium subtype were also recorded. The cognitive status of patients was measured according to the Mini-Mental State Examination at baseline, discharge, 30 days postoperatively and 3 months postoperatively.

RESULTS

A total of 112 patients (mean age, 52 years; 53.6% female) were enrolled; 56 were assigned to receive esketamine, and 56 were assigned to receive placebo. POD occurred in 13 (23.2%) patients in the esketamine group and in 25 (44.6%) patients in the placebo group (relative risk [RR], 0.52, 95% confidence interval [CI], 0.28-0.91; P = .018). Thirteen patients (23.2%) in the esketamine group and 24 (42.9%) patients in the placebo group had multiple episodes of delirium (RR, 0.54, 95% CI, 0.28-0.92), and 13 (23.2%) vs 22 (39.3%) patients exhibited the hyperactive subtype.

CONCLUSIONS

A single dose of esketamine (0.25 mg/kg) injected intravenously before anesthesia induction reduced the incidence of delirium in relatively young patients with ASA grade Ⅱ or Ⅲ who underwent on-pump cardiac surgery.

Perioperative esketamine administration for prevention of postpartum depression after the cesarean section: A systematic review and meta-analysis

BACKGROUND

Postpartum Depression (PPD) exerts a substantial negative effect on maternal well-being post-delivery, particularly among Cesarean Section (C/S) recipients. In this study, we aimed to review the efficacy of perioperative esketamine, the S-enantiomer of ketamine, in preventing PPD incidence and depressive symptoms as measured with the Edinburgh Postnatal Depression Scale (EPDS) after C/S.

METHODS

A systematic search for relevant articles was conducted in Scopus, PubMed, Web of Sciences, and PsycINFO until April 6, 2024. Meta-analyses were conducted using random-effect models to compare the PPD incidence and EPDS scores via log odds ratio and Hedge's g, respectively, during the first week post-C/S and at 42 days post-C/S in the esketamine and control group.

RESULTS

Fourteen studies, including 12 randomized controlled trials and 2 retrospective cohorts, were reviewed. Our meta-analyses found lower PPD incidence during the first week (log odds ratio: -0.956 [95 % confidence interval: -1.420, -0.491]) and at day 42 post-C/S (log odds ratio: -0.989 [95 % confidence interval: -1.707, -0.272]) among patients administered esketamine compared to controls. Additionally, EPDS scores for the esketamine group were significantly lower than controls during the first week (Hedge's g: -0.682 [95 % confidence interval: -1.088, -0.276]) and at day 42 post-C/S (Hedge's g: -0.614 [95 % confidence interval: -1.098, -0.129]).

LIMITATIONS

Presence of various concomitant medications and heterogeneous study designs.

CONCLUSION

Our review highlights the potential impact of esketamine in PPD prevention, as well as in alleviating depressive symptoms post-C/S, regardless of PPD occurrence, therefore suggesting the benefits of adding esketamine to peri-C/S analgesic regimen.

Plasma leptin levels are lower in females, but not males, with ketamine use disorder

Background: Ketamine has emerged as a prominent substance of misuse. Leptin, an adipocyte-derived polypeptide hormone, has been implicated in the development of addiction. Sex-specific changes in leptin levels have been demonstrated following acute ketamine administration; the persistence of long-term ketamine use on leptin levels is uncertain.Objectives: To assess the sex-difference of leptin levels, and their persistence, in individuals with ketamine use disorder (KUD) compared to healthy controls.Methods: Plasma leptin levels were measured in 62 healthy controls (37 males, 25 females) and 68 participants with KUD (50 males, 18 females) on the first day (baseline) and after 1 and 2 weeks of abstinence. As leptin levels are affected by body mass index (BMI), BMI-adjusted leptin (leptin/BMI ratio) was also examined. Mixed model for repeated measures was used to examine changes after ketamine abstinence.Results: Compared to same-sex controls, female, but not male, participants with KUD demonstrated lower leptin levels and leptin/BMI ratio at baseline, week 1, and week 2 (leptin levels: p = .001, 0.006 and 0.032, respectively; leptin/BMI ratio: p = .004, 0.022, and 0.09, respectively). Repeated measures showed that leptin levels and the leptin/BMI ratio increased after 2 weeks of abstinence in male participants with KUD (p = .002 and 0.011, respectively), but females did not show such an increase (p > .05).Conclusions: Sex-specific differences were observed in leptin levels and the leptin/BMI ratio in individuals with KUD compared to controls. Lower leptin levels in females with KUD persisted after 2 weeks of abstinence.

Efficacy of ketamine versus esketamine in the treatment of perioperative depression: A review

Depression is a significant factor contributing to postoperative occurrences, and patients diagnosed with depression have a higher risk for postoperative complications. Studies on cardiovascular surgery extensively addresses this concern. Several studies report that people who undergo coronary artery bypass graft surgery have a 20% chance of developing postoperative depression. A retrospective analysis of medical records spanning 21 years, involving 817 patients, revealed that approximately 40% of individuals undergoing coronary artery bypass grafting (CABG) were at risk of perioperative depression. Patients endure prolonged suffering from illness because each attempt with standard antidepressants requires several weeks to be effective. In addition, multi-drug combination adjuvants or combination medication therapy may alleviate symptoms for some individuals, but they also increase the risk of side effects. Conventional antidepressants primarily modulate the monoamine system, whereas different therapies target the serotonin, norepinephrine, and dopamine systems. Esketamine is a fast-acting antidepressant with high efficacy. Esketamine is the S-enantiomer of ketamine, a derivative of phencyclidine developed in 1956. Esketamine exerts its effect by targeting the glutaminergic system the glutaminergic system. In this paper, we discuss the current depression treatment strategies with a focus on the pharmacology and mechanism of action of esketamine. In addition, studies reporting use of esketamine to treat perioperative depressive symptoms are reviwed, and the potential future applications of the drug are presented.

The role of BDNF transcription in the antidepressant-like effects of 18β-glycyrrhetinic acid in a chronic social defeat stress model

BACKGROUND

Xiaoyaosan (XYS), a traditional Chinese medicine formulation, has been used in the treatment of depression. However, no studies have yet identified the active compounds responsible for its antidepressant effects in the brain.

STUDY DESIGN

We investigated the antidepressants effects of XYS and identified 18β-glycyrrhetinic acid (18β-GA) as the primary compound present in the brain following XYS injection. Furthermore, we explored the molecular mechanisms underlying the antidepressant-like effects of both XYS and 18β-GA.

METHODS

To investigate the antidepressant-like effects of XYS and elucidate the associated molecular mechanisms, we employed various methodologies, including cell cultures, the chronic social defeat stress (CSDS) model, behavioral tests, immunoprecipitation, quantitative PCR (qPCR) assays, Western blotting assays, luciferase assays, chromatin immunoprecipitation (ChIP) assays, immunofluorescence staining, and dendritic spine analysis.

RESULTS

We identified 18β-GA as the primary compound in the brain following XYS injection. In vitro, 18β-GA was found to bind with ERK (extracellular signal-regulated kinase), subsequently activating ERK kinase activity toward both c-Jun and cAMP response element binding protein (CREB). Moreover, 18β-GA activated brain-derived neurotrophic factor (BDNF) transcription by stimulating nuclear factor-erythroid factor 2-related factor 2 (Nrf2), c-Jun, and CREB, while also inhibiting methyl CpG binding protein 2 (MeCP2) both in vitro and in vivo. Chronic intraperitoneal (i.p.) administration of 18β-GA exhibited prophylactic antidepressant-like effects in a CSDS model, primarily by activating BDNF transcription in the medial prefrontal cortex (mPFC). Interestingly, a single i.p. injection of 18β-GA produced rapid and sustained antidepressant-like effects in CSDS-susceptible mice by engaging the BDNF-tropomyosin receptor kinase B (TrkB) signaling pathway in the mPFC.

CONCLUSION

These findings suggest that the activation of BDNF transcription in the mPFC underlies the antidepressant-like effects of 18β-GA, a key component of XYS in the brain.

Pediatric suicide: Review of a preventable tragedy

Concepts of suicide are explored in this issue with a focus on suicide in children and adolescents. The epidemiology of pediatric suicide in the United States is reviewed; also, risk and protective factors, as well as prevention strategies, are discussed. Suicide in the pediatric athlete and the potential protective effect of exercise are examined. In addition, this analysis addresses the beneficial role of psychological management as well as current research on pharmacologic treatment and brain stimulation procedures as part of comprehensive pediatric suicide prevention. Though death by suicide in pediatric persons has been and remains a tragic phenomenon, there is much that clinicians, other healthcare professionals, and society itself can accomplish in the prevention of pediatric suicide as well as the management of suicidality in our children and adolescents.

Role of oxidative phosphorylation in the antidepressant effects of arketamine via the vagus nerve-dependent spleen-brain axis

Arketamine, the (R)-enantiomer of ketamine, exhibits antidepressant-like effects in mice, though the precise molecular mechanisms remain elusive. It has been shown to reduce splenomegaly and depression-like behaviors in the chronic social defeat stress (CSDS) model of depression. This study investigated whether the spleen contributes to the antidepressant-like effects of arketamine in the CSDS model. We found that splenectomy significantly inhibited arketamine's antidepressant-like effects in CSDS-susceptible mice. RNA-sequencing analysis identified the oxidative phosphorylation (OXPHOS) pathway in the prefrontal cortex (PFC) as a key mediator of splenectomy's impact on arketamine's effects. Furthermore, oligomycin A, an inhibitor of the OXPHOS pathway, reversed the suppressive effects of splenectomy on arketamine's antidepressant-like effects. Specific genes within the OXPHOS pathways, such as COX11, UQCR11 and ATP5e, may contribute to these inhibitory effects. Notably, transforming growth factor (TGF)-β1, along with COX11, appears to modulate the suppressive effects of splenectomy and contribute to arketamine's antidepressant-like effects. Additionally, SRI-01138, an agonist of the TGF-β1 receptor, alleviated the inhibitory effects of splenectomy on arketamine's antidepressant-like effects. Subdiaphragmatic vagotomy also counteracted the inhibitory effects of splenectomy on arketamine's antidepressant-like effects in CSDS-susceptible mice. These findings suggest that the OXPHOS pathway and TGF-β1 in the PFC play significant roles in the antidepressant-like effects of arketamine, mediated through the spleen-brain axis via the vagus nerve.

Progress and trends of research on mineral elements for depression

Objective

To explore the research progress and trends on mineral elements and depression.

Methods

After querying the MeSH database and referring to the search rules, the search terms were selected and optimized to obtain the target literature collection. We analyzed the general characteristics of the literature, conducted network clustering and co-occurrence analysis, and carried out a narrative review of crucial literature.

Results

Bipolar disorder was a dominant topic in the retrieved literature, which saw a significant increase in 2010 and 2019-2020. Most studies focused on mineral elements, including lithium, calcium, magnesium, zinc, and copper. The majority of journals and disciplines were in the fields of psychiatry, neuropsychology, neuropharmacology, nutrition, medical informatics, chemistry, and public health. The United States had the highest proportion in terms of paper sources, most-cited articles, high-frequency citations, frontier citations, and high centrality citation. Regarding the influence of academic institutions, the top five were King's College London, the Chinese Academy of Sciences, University of Barcelona, INSERM, and Heidelberg University. Frontier keywords included bipolar disorder, drinking water, (neuro)inflammation, gut microbiota, and systematic analysis. Research on lithium response, magnesium supplementation, and treatment-resistant unipolar depression increased significantly after 2013.

Conclusion

Global adverse events may have indirectly driven the progress in related research. Although the literature from the United States represents an absolute majority, its influence on academic institutions is relatively weaker. Multiple pieces of evidence support the efficacy of lithium in treating bipolar disorder (BD). A series of key discoveries have led to a paradigm shift in research, leading to increasingly detailed studies on the role of magnesium, calcium, zinc, and copper in the treatment of depression. Most studies on mineral elements remain diverse and inconclusive. The potential toxicity and side effects of some elements warrant careful attention.

Esketamine Prevents Postoperative Emotional and Cognitive Dysfunction by Suppressing Microglial M1 Polarization and Regulating the BDNF-TrkB Pathway in Ageing Rats with Preoperative Sleep Disturbance

Postoperative depression (POD) and postoperative cognitive dysfunction (POCD) have placed heavy burden on patients' physical and mental health in recent years. Sleep disturbance before surgery is a common phenomenon that has been increasingly believed to affect patients' recovery, especially in aged patients, while little attention has been paid to sleep disruption before surgery and the potential mechanism remains ambiguous. Ketamine has been reported to attenuate POCD after cardiac surgery and elicit rapid-acting and sustained antidepressant actions. The present study aimed to clarify the effect of esketamine's (the S-enantiomer of ketamine) protective effects and possible mechanisms of action in POCD and POD. Our results showed that sleep disturbance before surgery exacerbated microglial M1 polarization and microglial BDNF-TrkB signalling dysfunction induced by surgery, resulting in postoperative emotional changes and cognitive impairments. Notably, treatment with esketamine reversed the behavioural abnormalities through inhibiting the M1 polarization of microglia and the inflammatory response thus improving BDNF-TrkB signalling in vivo and vitro. In addition, esketamine administration also reversed the impaired hippocampal synaptic plasticity which has been perturbed by sleep disturbance and surgery. These findings warrant further investigations into the interplay of esketamine and may provide novel ideas for the implication of preoperative preparations and the prevention of postoperative brain-related complications.

Expanding the Role of Chiral Drugs and Chiral Nanomaterials as a Potential Therapeutic Tool

Chirality, the property of molecules having mirror-image forms, plays a crucial role in pharmaceutical and biomedical research. This review highlights its growing importance, emphasizing how chiral drugs and nanomaterials impact drug effectiveness, safety, and diagnostics. Chiral molecules serve as precise diagnostic tools, aiding in accurate disease detection through unique biomolecule interactions. The article extensively covers chiral drug applications in treating cardiovascular diseases, CNS disorders, local anesthesia, anti-inflammatories, antimicrobials, and anticancer drugs. Additionally, it explores the emerging field of chiral nanomaterials, highlighting their suitability for biomedical applications in diagnostics and therapeutics, enhancing medical treatments.

Ketamine induces insomnia-like symptom of zebrafish at environmentally relevant concentrations by mediating GABAergic synapse

Although the stimulative effects on the normal behaviors of fish posed by ketamine (KET) were well-studied, the adverse effects on the behavioral functions induced by KET at nighttime were unknown. Here, we used zebrafish larvae as a model exposed to KET (10, 50, 100, and 250 ng/L) at environmental levels for 21 days. The behavioral functions at nighttime, morphological changes during exposure stage, and alterations on the associated genes transcriptional levels of fish were determined. The difficultly initiating sleep was found in the fish exposed to KET, while the sleep duration of the animals was at the normal levels in exposure groups. The significant suppressions of the developmentally relevant genes, including bmp2, bmp4, and pth2ra were consistent with the developmental abnormalities of fish found in exposure groups. Moreover, the expression of γ-aminobutyric acid (GABA) receptor increased and melatonin (MTN) receptor decreased while the levels of GABA and MTN remained unchanged after exposure, by gene expression analysis and molecular docking. In addition, the transcriptional expression of apoptotic genes, including tp53, aifm1, and casp6, was significantly upregulated by KET. After a 7-day recovery, the insomnia-like behaviors (shorter sleep duration) were observed in zebrafish from the 250 ng/L-KET group. Accordingly, the adverse outcome pathway framework of KET was constructed by prognostic assessment of zebrafish larvae. This study suggested that the adverse outcomes of KET on the sleep health of organisms at environmentally relevant concentrations should be concerned.

Efficacy of Esketamine among patients with treatment resistant depression in a 'real world' health-care setting in Israel

One in five people will likely suffer from major depressive disorder (MDD) during their life. Thirty percent of those with MDD will experience Treatment Resistant Depression (TRD), which is characterized by a failure to respond to two adequately administered trials of antidepressants. Esketamine is a rapidly acting intranasal antidepressant. Present-day Esketamine research has limited data in real-world populations. This study aimed to assess Esketamine treatment in a real-world community-based population. This naturalistic retrospective study included 94 individuals age 18 and above diagnosed with TRD, treated with Esketamine in an outpatient setting. The treatment was given in a single clinic, from January 2021 to January 2023, following approval of the Institutional Internal Review Board. The treatment included an acute phase (biweekly treatment, continuing 4-8 weeks), followed by a maintenance phase (once a week to once a month, for 6-12 months). Dosing ranged from 28 mg to 84 mg. Demographic and clinical data were retrospectively gathered. Depressive symptoms were assessed using the Quick Inventory of Depressive Symptomatology, at baseline and during each treatment phase. All patients completed the acute phase. About 60% completed the maintenance phase. Linear improvement of depressive symptoms was revealed in both phases. A sub-analysis of patients with comorbid personality disorder revealed a similar improvement pattern in the acute phase with milder improvement during the maintenance phase, compared to the other patients. This study supports the use of Esketamine for TRD, including patients with comorbid personality disorder and previous electroconvulsive therapy.

Design, Synthesis and Biological Evaluation of Novel Ketamine Derivatives as NMDAR Antagonists

Depression is a chronic, severe, and often life-threatening neurological disorder. It not only causes depression in patients and affects daily life but, in severe cases, may lead to suicidal behavior and have adverse effects on families and society. In recent years, it has been found that sub-anesthetic doses of ketamine have a rapid antidepressant effect on patients with treatment-resistant depression and can significantly reduce the suicidal tendencies of patients with major depressive disorder. Current studies suggest that ketamine may exert antidepressant effects by blocking NMDAR ion channels, but its anesthetic and psychotomimetic side effects limit its application. Here, we report efforts to design and synthesize a novel series of ketamine derivatives of NMDAR antagonists, among which compounds 23 and 24 have improved activity compared with ketamine, introducing a new direction for the development of rapid-acting antidepressant drugs.

The Relationship Between Perioperative Use of Esketamine and Postpartum Depression Risk: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

PURPOSE

To determine whether perioperative esketamine use decreases the risk of postpartum depression (PPD).

METHODS

Online search of PubMed, Web of Science, and Embase was conducted to identify relevant studies. Key words for search included, but were not limited to, postpartum depression, esketamine, and clinical trials. The mean and standard deviation of the Edinburgh Postnatal Depression Scale (EPDS) scores were extracted from the studies as primary parameters.

RESULTS

The literature search identified 226 articles, of which 5 met the criteria and were enrolled in the study. In total, 886 patients in the studies were taken into analysis. The EPDS scores in the esketamine group were lower than those of the control group at the early stage of puerperium (WMD=-2.05, 95% CI: -3.77, -0.34, p=0.019), whereas there was no significant difference at the middle and later stages (WMD=-1.41, 95% CI: -2.86, 0.04, p=0.056). The sensitivity analyses indicated that the result for the early stage was stable, whereas it was unreliable for the middle and later stages. The results of the Egger's test indicated no publication bias.

CONCLUSION

Perioperative use of esketamine contributes to a lower risk of PPD at the early stage of puerperium but not at the middle and later stages. To further verify this conclusion, more high-quality studies are required.

Efficacy and safety of esketamine for perioperative depression in patients undergoing elective surgery: A meta-analysis of randomized controlled trials

BACKGROUND

Depression is a prevalent mood disorder during the perioperative period, with both preoperative concurrent depression and new-onset postoperative depression impacting postoperative recovery. Recent studies have indicated that the dissociative anesthetic esketamine may alleviate perioperative depressive symptoms.

OBJECTIVE

This meta-analysis aimed to assess the efficacy and safety of esketamine in treating perioperative depression.

METHODS

We selected randomized controlled trials comparing esketamine to placebo in terms of postoperative depressive symptoms. The primary outcome was postoperative depression scores, with secondary outcomes including the prevalence of postoperative depression, pain scores using the Visual Analogue Scale or Numeric Rating Scale, and incidences of adverse reactions such as nausea/vomiting, dizziness, dreams/nightmares, hallucinations.

RESULTS

We enrolled a total of 17 studies involving 2462 patients. The esketamine group demonstrated a significant reduction in postoperative depression scores within one week after surgery (SMD -0.47, 95% CI (-0.66, -0.27), P < 0.001) and over the long term (SMD -0.44, 95% CI (-0.79, -0.09), P = 0.01). Furthermore, esketamine significantly decreased the prevalence of postoperative depression both within one week (RR 0.46, 95% CI (0.33, 0.63), P < 0.001) and over the long term (RR 0.50, 95% CI (0.36, 0.70), P < 0.001). Additionally, esketamine effectively relieved pain on the first postoperative day compared to control. However, it also increased the risks of dizziness and hallucinations for a short time.

CONCLUSION

This meta-analysis suggests that the intraoperative or postoperative application of esketamine could be a potentially effective treatment for perioperative depression, although the increased risk of adverse reactions should be considered.

A role of gut-brain axis on prophylactic actions of arketamine in male mice exposed to chronic restrain stress

The gut-brain axis, which includes gut microbiota and microbiome-derived metabolites, might be implicated in depression. We reported the sustained prophylactic effects of a new antidepressant arketamine in chronic restrain stress (CRS) model of depression. In this study, we investigated the role of gut-brain axis on the prophylactic effects of arketamine in the CRS (7 days) model. Pretreatment with arketamine (10 mg/kg, 1 day prior to the CRS onset) significantly prevented CRS-induced body weight loss, increased immobility time of forced swimming test, decreased sucrose preference of sucrose preference test, and reduced expressions of synaptic proteins (GluA1 and PSD-95) in the prefrontal cortex (PFC) in the male mice. Gut microbiota analysis showed that pretreatment with arketamine might restore altered abundance of gut microbiota in CRS-exposed mice. An untargeted metabolomics analysis revealed four metabolites (e.g., L-leucine, N-acetyl-l-glutamine, 2-(2,4-dichlorophenyl)-3-[4-(dimethylamino)phenyl]acrylonitrile, L-threonine amide) that were altered between control and CRS group; however, there were found to be altered between the saline + CRS group and the arketamine + CRS group. Network analysis demonstrated correlations among synaptic proteins in the PFC and certain microbiota, and blood metabolites. These findings suggest that gut-brain axis, including its metabolites, might partially contribute to the persistent prophylactic effects of arketamine in the CRS model.

Ketamine and its enantiomers for depression: a bibliometric analysis from 2000 to 2023

Ketamine has demonstrated rapid and sustained antidepressant effects, marking its emergence as an innovative treatment of depression. Despite the growing number of preclinical and clinical studies exploring the antidepressant effects of ketamine and its enantiomers, a comprehensive bibliometric analysis in this field has yet to be conducted. This study employs bibliometric methods and visualization tools to examine the literature and identify key topics related to the antidepressant effects of ketamine and its enantiomers. We sourced publications on the antidepressant effects of ketamine and its enantiomers from the Web of Science Core Collection (WOSCC) database, covering the period from 2000 to 2023. Tools such as VOSviewer, CiteSpace and the R package "bibliometrix" were utilized for visual analysis. The study included 4,274 publications, with a notable increase in publications peaking in 2022. Co-occurrence analysis highlighted two primary research focal points: the efficacy and safety of ketamine and its enantiomers in treating depression, and the mechanisms behind their antidepressant effects. In conclusion, this analysis revealed a significant increase in research on the antidepressant effects of ketamine and its enantiomers over the past two decades, leading to the approval of esketamine nasal spray for treatment-resistant depression. The rapid antidepressant effects of ketamine have spurred further studies into its mechanisms of action and the search for new antidepressants with fewer side effects.

Altered intersubject functional variability of brain white-matter in major depressive disorder and its association with gene expression profiles

Major depressive disorder (MDD) is a clinically heterogeneous disorder. Its mechanism is still unknown. Although the altered intersubject variability in functional connectivity (IVFC) within gray-matter has been reported in MDD, the alterations to IVFC within white-matter (WM-IVFC) remain unknown. Based on the resting-state functional MRI data of discovery (145 MDD patients and 119 healthy controls [HCs]) and validation cohorts (54 MDD patients, and 78 HCs), we compared the WM-IVFC between the two groups. We further assessed the meta-analytic cognitive functions related to the alterations. The discriminant WM-IVFC values were used to classify MDD patients and predict clinical symptoms in patients. In combination with the Allen Human Brain Atlas, transcriptome-neuroimaging association analyses were further conducted to investigate gene expression profiles associated with WM-IVFC alterations in MDD, followed by a set of gene functional characteristic analyses. We found extensive WM-IVFC alterations in MDD compared to HCs, which were associated with multiple behavioral domains, including sensorimotor processes and higher-order functions. The discriminant WM-IVFC could not only effectively distinguish MDD patients from HCs with an area under curve ranging from 0.889 to 0.901 across three classifiers, but significantly predict depression severity (r = 0.575, p = 0.002) and suicide risk (r = 0.384, p = 0.040) in patients. Furthermore, the variability-related genes were enriched for synapse, neuronal system, and ion channel, and predominantly expressed in excitatory and inhibitory neurons. Our results obtained good reproducibility in the validation cohort. These findings revealed intersubject functional variability changes of brain WM in MDD and its linkage with gene expression profiles, providing potential implications for understanding the high clinical heterogeneity of MDD.

Ketamine in Substance Use Disorder Treatment: A Narrative Review

Substance use disorder (SUD) continues to pose a significant global health challenge, necessitating innovative and effective therapeutic interventions. Ketamine, traditionally recognized for its anesthetic properties, has emerged as a novel and promising avenue for the treatment of SUD. This narrative review critically examines the current body of literature surrounding the use of ketamine in various forms and settings for individuals grappling with substance abuse. The review explores the neurobiological underpinnings of ketamine's potential therapeutic effects in SUD, shedding light on its impact on glutamatergic neurotransmission, neuroplasticity, and reward pathways. Special attention is given to the psychotropic and dissociative properties of ketamine, exploring their implications for both therapeutic outcomes and patient experience. Ultimately, this review aims to provide a comprehensive overview of the current state of knowledge regarding ketamine's role in the treatment of SUD, emphasizing the need for further research and clinical exploration. As we navigate the complex terrain of addiction medicine, understanding the nuances of ketamine's potential in SUD holds promise for the development of more effective and personalized therapeutic strategies.

Role of Flt3l and Rps15 in ketamine anesthesia

Ketamine is the only intravenous narcotic that has sedative, analgesic, and anesthetic effects. However, the role of Flt3l and ribosomal protein S15 (Rps15) in ketamine anesthesia remains unclear. GSE26364 and GSE93041 were downloaded from gene expression omnibus. Multiple datasets were merged and batched. Differentially expressed genes (DEGs) were screened and weighted gene co-expression network analysis was performed. Construction and analysis of protein-protein interaction network. Gene ontology (GO) and Kyoto Encyclopedia of Gene and Genome were performed. A heat map of gene expression was drawn. TargetScan was used to screen miRNAs regulating DEGs. 882 DEGs were identified. According to the GO analysis, these DEGs were mainly enriched in cell differentiation, extracellular region, and cytoplasm. The Kyoto Encyclopedia of Gene and Genome analysis revealed enrichment in pathways such as the PPAR signaling pathway, TNF signaling pathway, Hippo signaling pathway, and IL-17 signaling pathway. In the Metascape enrichment analysis, GO enrichment categories included leukocyte differentiation, negative regulation of CREB transcription factor activity, and positive regulation of cell cycle. The protein-protein interaction network showed 10 core genes (Rpl7, Rpl18, Rps15, Rpl7l1, Flt3l, Rps16, Eprs, Rps19, Rps28, Rplp2).Gene expression heatmap showed that core genes (Rplp2, Flt3l, Rps15) were highly expressed in samples treated with ketamine anesthesia. Flt3l and Rps15 are highly expressed during ketamine anesthesia, and may be molecular targets.

Are "mystical experiences" essential for antidepressant actions of ketamine and the classic psychedelics?

The growing interest in the rapid and sustained antidepressant effects of the dissociative anesthetic ketamine and classic psychedelics, such as psilocybin, is remarkable. However, both ketamine and psychedelics are known to induce acute mystical experiences; ketamine can cause dissociative symptoms such as out-of-body experience, while psychedelics typically bring about hallucinogenic experiences, like a profound sense of unity with the universe or nature. The role of these mystical experiences in enhancing the antidepressant outcomes for patients with depression is currently an area of ongoing investigation and debate. Clinical studies have shown that the dissociative symptoms following the administration of ketamine or (S)-ketamine (esketamine) are not directly linked to their antidepressant properties. In contrast, the antidepressant potential of (R)-ketamine (arketamine), thought to lack dissociative side effects, has yet to be conclusively proven in large-scale clinical trials. Moreover, although the activation of the serotonin 5-HT2A receptor is crucial for the hallucinogenic effects of psychedelics in humans, its precise role in their antidepressant action is still under discussion. This article explores the importance of mystical experiences in enhancing the antidepressant efficacy of both ketamine and classic psychedelics.

Gut microbiota-derived short-chain fatty acids and depression: deep insight into biological mechanisms and potential applications

The gut microbiota is a complex and dynamic ecosystem known as the 'second brain'. Composing the microbiota-gut-brain axis, the gut microbiota and its metabolites regulate the central nervous system through neural, endocrine and immune pathways to ensure the normal functioning of the organism, tuning individuals' health and disease status. Short-chain fatty acids (SCFAs), the main bioactive metabolites of the gut microbiota, are involved in several neuropsychiatric disorders, including depression. SCFAs have essential effects on each component of the microbiota-gut-brain axis in depression. In the present review, the roles of major SCFAs (acetate, propionate and butyrate) in the pathophysiology of depression are summarised with respect to chronic cerebral hypoperfusion, neuroinflammation, host epigenome and neuroendocrine alterations. Concluding remarks on the biological mechanisms related to gut microbiota will hopefully address the clinical value of microbiota-related treatments for depression.

BDNF/CREB signaling pathway contribution in depression pathogenesis: A survey on the non-pharmacological therapeutic opportunities for gut microbiota dysbiosis

Emerging evidence supports the gut microbiota and the brain communication in general health. This axis may affect behavior through modulating neurotransmission, and thereby involve in the pathogenesis and/or progression of different neuropsychiatric disorders such as depression. Brain-derived neurotrophic factor and cAMP response element-binding protein known as CREB/BDNF pathway plays have critical functions in the pathogenesis of depression as the same of mechanisms related to antidepressants. However, the putative causal significance of the CREB/BDNF signaling cascade in the gut-brain axis in depression remains unknown. Also interventions such as probiotics supplementation and exercise can influence microbiome also improve bidirectional communication of gut and brain. In this review we aim to explain the BDNF/CREB signaling pathway and gut microbiota dysfunction and then evaluate the potential role of probiotics, prebiotics, and exercise as a therapeutic target in the gut microbiota dysfunction induced depression. The current narrative review will specifically focus on the impact of exercise and diet on the intestinal microbiota component, as well as the effect that these therapies may have on the microbiota to alleviate depressive symptoms. Finally, we look at how BDNF/CREB signaling pathway may exert distinct effects on depression and gut microbiota dysfunction.

A novel NMDA receptor modulator: the antidepressant effect and mechanism of GW043

AIMS

The N-methyl-D-aspartate (NMDA) receptor (NMDAR) has been proven to be strongly correlated with rapid antidepressant effects. Here, GW043, as a new compound targeting NMDAR, we explored its antidepressant effects and its mechanism of action.

METHODS

Our study utilized electrophysiological techniques to confirm the effect of GW043 on NMDAR currents. Additionally, we assessed the selectivity of GW043 through high-throughput receptor-ligand binding experiments. The antidepressant properties of GW043 were examined using rodent behavioral models including the Forced Swim Test (FST), Tail Suspension Test (TST), and Chronic Unpredictable Mild Stress (CUMS). Mechanistic insight into GW043's onset was gained through western blot analysis, BrdU staining, Golgi staining, and electrophysiological techniques.

RESULTS

Electrophysiological studies indicated that GW043 acts as a partial agonist of NMDAR. Behavioral experiments confirmed the antidepressant effect of GW043 in rodents. Mechanistic investigations revealed that GW043 modulates synaptic plasticity through the LTP and BDNF-mTOR pathways, consequently leading to an increase in the number of newborn neurons and subsequent antidepressant effects.

CONCLUSION

Our findings disclose that GW043, as a partial agonist of NMDAR, can reverse depression-like behaviors in rats by modulating synaptic plasticity, indicating its potential as an antidepressant agent.

Esketamine induces apoptosis of nasopharyngeal carcinoma cells through the PERK/CHOP pathway

Nasopharyngeal carcinoma, a malignant tumor prevalent in southeast Asia and north Africa, still lacks effective treatment. Esketamine, an N-methyl-D-aspartatic acid (NMDA) receptor (NMDAR) antagonist, is widely used in clinical anesthesia. Emerging evidence suggests that esketamine plays an important role in inhibiting tumor cell activity. However, the underlying mechanisms of esketamine on nasopharyngeal carcinoma remain unknown. In this study, we found that esketamine inhibited the proliferation and migration of nasopharyngeal carcinoma cells. Mechanically, transcriptome sequencing and subsequent verification experiments revealed that esketamine promoted the apoptosis of nasopharyngeal carcinoma cells through endoplasmic reticulum stress PERK/ATF4/CHOP signaling pathway mediated by NMDAR. Additionally, when combined with esketamine, the inhibitory effect of cisplatin on the proliferation of nasopharyngeal carcinoma cells was significantly enhanced. These findings provide new insights into future anti-nasopharyngeal carcinoma clinical strategies via targeting the NMDAR/PERK/CHOP axis alone or in combination with cisplatin.

Esketamine-induced post-traumatic stress disorder flashbacks during treatment-resistant depression indication: is it just a side effect?

Background

Posttraumatic stress disorder (PTSD) is a severe and frequent affection that is highly comorbid to major depressive disorder. Comorbid PTSD and depression are usually treatment-resistant, with a high risk of functional impairment and suicide. Esketamine nasal spray is a recent validated treatment for treatment-resistant depression (TRD), but its efficacy on comorbid TRD-PTSD remains insufficiently documented. In particular, flashbacks can occur during esketamine administration and their influence on clinical outcomes is unknown.

Objectives

Our main objective was to describe esketamine-induced traumatic flashbacks and their impact on clinical trajectories within a sample of patients with comorbid TRD-PTSD.

Methods

We retrospectively collected clinical data of patients receiving esketamine nasal spray for TRD with comorbid PTSD who experienced at least one flashback of their trauma during esketamine sessions across 11 psychiatric departments.

Results

Between February 2020 and March 2023, 22 adult patients with TRD met inclusion criteria. In sixteen patients (72.7%) flashbacks disappeared as the sessions progressed. In six patients (27.3%), esketamine treatment was stopped because of persistent flashbacks. When esketamine was continued, clinical response was observed both for depression and PTSD (depression response rate: 45.5% and remission rate: 22.7%; PTSD response rate: 45.5% and remission: 18.2%).

Limitations

The retrospective design of the study and the absence of a comparator group are the main limitations of our study.

Conclusions

Our results suggest that the occurrence of esketamine-induced traumatic flashbacks does not hinder clinical response. On the contrary, when managed appropriately and combined with targeted psychotherapy, it could even contribute to positive outcomes.

Ketamine - A New Antidepressant Drug with Anti-Inflammatory Properties

Ketamine is a new, potent and rapid-acting antidepressant approved for therapy of treatment-resistant depression, which has a different mechanism of action than currently-available antidepressant therapies. It owes its uniquely potent antidepressant properties to a complex mechanism of action, which currently remains unclear. However, it is thought that it acts by modulating the functioning of the glutamatergic system, which plays an important role in the process of neuroplasticity associated with depression. However, preclinical and clinical studies have also found ketamine to reduce inflammation, either directly or indirectly (by activating neuroprotective branches of the kynurenine pathway), among patients exhibiting higher levels of inflammation. Inflammation and immune system activation are believed to play key roles in the development and course of depression. Therefore, the present work examines the role of the antidepressant effect of ketamine and its anti-inflammatory properties in the treatment of depression. SIGNIFICANCE STATEMENT: The present work examines the relationship between the antidepressant effect of ketamine and its anti-inflammatory properties, and the resulting benefits in treatment-resistant depression (TRD). The antidepressant mechanism of ketamine remains unclear, and there is an urgent need to develop new therapeutic strategies for treatment of depression, particularly TRD.

cAMP-dependent protein kinase signaling is required for (2R,6R)-hydroxynorketamine to potentiate hippocampal glutamatergic transmission

(2R,6R)-Hydroxynorketamine (HNK) is a ketamine metabolite that shows rapid antidepressant-like effects in preclinical studies and lacks the adverse N-methyl-d-aspartate receptor (NMDAR) inhibition-related properties of ketamine. Investigating how (2R,6R)-HNK exerts its antidepressant actions may be informative in the design of novel pharmacotherapies with improved safety and efficacy. We sought to identify the molecular substrates through which (2R,6R)-HNK induces functional changes at excitatory synapses, a prevailing hypothesis for how rapid antidepressant effects are initiated. We recorded excitatory postsynaptic potentials in hippocampal slices from male Wistar Kyoto rats, which have impaired hippocampal plasticity and are resistant to traditional antidepressants. (2R,6R)-HNK (10 µM) led to a rapid potentiation of electrically evoked excitatory postsynaptic potentials at Schaffer collateral CA1 stratum radiatum synapses. This potentiation was associated with a decrease in paired pulse facilitation, suggesting an increase in the probability of glutamate release. The (2R,6R)-HNK-induced potentiation was blocked by inhibiting either cyclic adenosine monophosphate (cAMP) or its downstream target, cAMP-dependent protein kinase (PKA). As cAMP is a potent regulator of brain-derived neurotrophic factor (BDNF) release, we assessed whether (2R,6R)-HNK exerts this acute potentiation through a rapid increase in cAMP-dependent BDNF-TrkB signaling. We found that the cAMP-PKA-dependent potentiation was not dependent on TrkB activation by BDNF, which functionally delimits the acute synaptic effects of (2R,6R)-HNK from its sustained BDNF-dependent actions in vivo. These results suggest that, by potentiating glutamate release via cAMP-PKA signaling, (2R,6R)-HNK initiates acute adaptations in fast excitatory synaptic transmission that promote structural plasticity leading to maintained antidepressant action.NEW & NOTEWORTHY Ketamine is a rapid-acting antidepressant and its preclinical effects are mimicked by its (2R,6R)-(HNK) metabolite. We found that (2R,6R)-HNK initiates acute adaptations in fast excitatory synaptic transmission by potentiating glutamate release via cAMP-PKA signaling at hippocampal Schaffer collateral synapses. This cAMP-PKA-dependent potentiation was not dependent on TrkB activation by BDNF, which functionally delimits the rapid synaptic effects of (2R,6R)-HNK from its sustained BDNF-dependent actions that are thought to maintain antidepressant action in vivo.