New Insights Into Major Depression and the Treatment of Bipolar Depression

Saikosaponin A alleviates depressive-like behavior induced by reserpine in mice by regulating gut microflora and inflammatory responses

Saikosaponin A (SSA), a key ingredient of Chaihu-Shugan-San, has been shown to possess anti-inflammatory, antioxidant and antidepressant properties. Therefore, the present study aimed to investigate the potential mechanism of action and the effect of SSA on reserpine-induced depressive-like symptoms in mice. Establishing mouse model of depression using intraperitoneal injection of reserpine (RSP). Forced swimming test, tail suspension test and sucrose preference test were used to assess depression-like behavior in mice. The results showed that mice exposed to RSP not only showed weight loss and depressive behavior, but also elevated levels of IL-1β and TNF-α, as well as upregulated levels of reactive oxygen species (ROS) and lipid peroxides in the hippocampus. Detection of changes in the intestinal flora of mice using 16S rRNA, it was observed that the intestinal flora changed following SSA treatment. Not only was there an increase in the overall abundance of the intestinal microbiota, but there was also a significant down-regulation of the Firmicutes and an up-regulation of the Verrucomicrobia at the phylum level. Furthermore, SSA treatment markedly improved depressive-like behavior induced by RSP, alleviated damage to the hippocampus, elevated levels of monoamine neurotransmitters, suppressed inflammatory factors in the hippocampus, reduced hippocampal oxidative stress, and restored gut microbiota disruption in RSP-induced mice. The findings propose that SSA has the potential to alleviate depressive symptoms in mice by enhancing monoamine neurotransmitter levels, suppressing hippocampal inflammation, and modifying gut microbial composition.

Esketamine Nasal Spray: Rapid Relief for TRD and Suicide Prevention-Mechanisms and Pharmacodynamics

Esketamine nasal spray has emerged as a promising rapid-relief therapy for treatment-resistant depression (TRD) and suicide prevention. This review examines the chemical structure and pharmacodynamics of esketamine, highlighting its primary action on NMDA receptors and additional effects on AMPA receptors, opioid receptors, monoaminergic receptors, and inflammatory pathways. Despite the synergistic mechanisms contributing to its clinical benefits not being fully understood, future studies are essential to refine our understanding and optimize clinical use. Clinical research indicates that esketamine effectively alleviates depressive symptoms and prevents suicidal behavior in TRD patients, demonstrating good safety and efficacy over extended periods. Specifically, multiple randomized controlled trials have shown that esketamine reduces depressive symptoms within hours and maintains these benefits over several weeks, with a favorable safety profile and minimal side effects observed in long-term use. The approval of esketamine for TRD has significant implications for healthcare practices and policies, offering a new therapeutic option that addresses the urgent needs of patients with severe depression.

Monomeric pilose antler peptide improves depression-like behavior in mice by inhibiting FGFR3 protein expression

ETHNOPHARMACOLOGICAL RELEVANCE

It has been found that pilose antler peptide has an antidepressant effect on depression. However, the exact molecular mechanism of its antidepressant effect is still unclear.

AIM OF THE STUDY

The study sought to determine the impact of monomeric pilose antler peptide (PAP; sequence LVLVEAELRE) on depression as well as investigate potential molecular mechanisms.

MATERIALS AND METHODS

Chronic unexpected mild stress (CUMS) was used to establish the model, and the effect of PAP on CUMS mice was detected by the behavioral test. The influence of PAP on neuronal cells and dendritic spine density was observed by immunofluorescence and Golgi staining. FGFR3 and the CaMKII-associated pathway were identified using quantitative real-time polymerase chain reaction, and Western blot analysis was utilized to measure their proteins and gene expression levels. Molecular docking and microscale thermophoresis were applied to detect the binding of PAP and FGFR3. Finally, the effect of FGFR3's overexpression on PAP treatment of depression was detected.

RESULTS

PAP alleviated the changes in depressive behavior induced by CUMS, promoted the growth of nerve cells, and the density of dendritic spines was increased to its original state. PAP therapy successfully downregulated the expression of FGFR3 and ERK1/2 while upregulating the expression of CREB, BDNF, and CaMKII.

CONCLUSION

Based on the current research, PAP has a therapeutic effect on depression brought on by CUMS by inhibiting FGFR3 expression and enhancing synaptic plasticity.

Effects of esketamine and fluoxetine on depression-like behaviors in chronic variable stress: a role of plasma inflammatory factors

Mounting evidence has identified the rapid and sustained antidepressive and anxiolytic-like effects of esketamine. However, the underlying mechanism of this no-monoamine target rapid-onset antidepressant is still underexplored. Immune-inflammatory pathways and cell-mediated immune activation, mainly including inflammatory cytokines in plasma, play a pivotal role in the pathogenesis of major depressive disorder and are also a potential therapeutic target for MDD. The current study was designed to clarify the role of esketamine on the expression of plasma cytokines in a depressive-like model introduced by chronic variable stress (CVS). In this study, a 21-day consecutive CVS protocol was applied to produce depressive- and anxiety-like behaviors. After the single dose or 7-day repeated administration of esketamine or fluoxetine, the depressive- and anxiety-like behaviors and the expression of inflammatory cytokines in plasma were examined. Both a single dose of esketamine and 7-days repeated fluoxetine administration elicited anti-depressive and anxiolytic effects in mice exposed to CVS. Additionally, CVS produced significant changes in the plasma inflammatory factors, notably increasing the expression of IL-1β, IL-6, IL-8, IL-17A, TNFα, IL-4, IL-9, IL-24, IL-37, IFN-β, and CXCL12, while reducing IL-10 and IL-33. With the administration of esketamine and fluoxetine, CVS-produced inflammatory disturbances were partially normalized. Together, our findings provide a novel insight that acute esketamine treatment could rescue CVS-produced depressive-like and anxiety-like behaviors in mice by normalizing the expression of inflammatory cytokines; this effect was similar to the repeated administration of fluoxetine. These results contributed to the understating of rapid anti-depressant effects elicited by esketamine.

Serum Levels of Zinc, Albumin, Interleukin-6 and CRP in Patients with Unipolar and Bipolar Depression: Cross Sectional Study

Unipolar (UD) and bipolar depression (BDD) show a high degree of similarity in clinical presentations, which complicates the differential diagnosis of these disorders. The aim of this study was to investigate the serum levels of interleukin 6 (IL-6), C-reactive protein (CRP), albumin (Alb), and zinc (Zn) in patients with UD, BDD, and healthy controls (HC). A total of 211 samples were collected: 131 patient samples (65 UD and 68 BDD) and 80 HC. The Montgomery-Asberg Depression Rating Scale (MADRS), along with the Hamilton Depression Rating Scale (HAMD-17), were administered to patient groups to evaluate symptoms. A cross-sectional study was performed to analyse the serum levels of IL-6, CRP, albumin, and zinc. The concentration of CRP was determined using the immunoturbidimetry method, zinc using the colorimetric method, and albumin using the colorimetric method with bromocresol green on the Alinity c device. IL-6 cytokine concentration in serum samples was ascertained using a commercial enzyme immunoassay, ELISA. We found no significant differences in serum concentrations of zinc, albumin, CRP, and IL-6 between the groups of patients with unipolar and bipolar depression. There was a significant statistical difference (p < 0.001) between serum levels of all investigated parameters in both groups of depressed patients in comparison with HC. Furthermore, correlations with specific items on HAMD-17; (namely, hypochondrias, work and activities, somatic symptoms-general, and weight loss) and on MADRS (concentration difficulties, lassitude) were observed in both patient groups. These findings confirm the presence of low-grade inflammation in depression, thus adding better insight into the inflammation hypothesis directed to explain the aetiology of depressive disorders. Our results do not indicate potential biomarkers for distinguishing between unipolar and bipolar depression.

Systemic inflammation and oxidative stress markers in patients with unipolar and bipolar depression: A large-scale study

OBJECTIVE

Numerous studies have demonstrated that neutrophil/HDL ratio (NHR), lymphocyte/HDL ratio (LHR), monocyte/HDL (MHR) ratio, platelet/HDL ratio (PHR), neutrophil/ALB ratio (NAR) and platelet/ALB ratio (PAR) can serve as systemic inflammation and oxidative stress markers in a variety of diseases. However, few studies have estimated the associations of these markers with unipolar depression (UD) and bipolar depression (BD), as well as psychotic symptoms in UD and BD.

METHODS

6297 UD patients, 1828 BD patients and 7630 healthy subjects were recruited. The differences in these indicators among different groups were compared, and the influencing factors for the occurrence of UD or BD and psychotic symptoms were analyzed.

RESULTS

These ratios displayed unique variation patterns across different diagnostic groups. BD group exhibited higher NHR, LHR, MHR, NAR and lower PAR than UD and HC groups, UD group showed higher MHR than HC group. The psychotic UD group had higher NHR, LHR, MHR and NAR than non-psychotic UD group. Higher LHR, MHR, NAR and lower PAR were risk factors in BD when compared to UD group.

CONCLUSIONS

Our study demonstrated differences in inflammation and oxidative stress profile between UD and BD patients, as well as between subjects with or without psychotic symptom exist, highlighting the role of inflammation and oxidative stress in the pathophysiology of UD and BD.

Shared and specific neurobiology in bipolar disorder and unipolar disorder: Evidence based on the connectome gradient and a transcriptome-connectome association study

BACKGROUND

Distinguishing bipolar disorder (BD) and unipolar disorder (UD) remains challenging. To identify the common and diagnosis-specific neuropathological alterations and their potential molecular mechanisms in patients with UD and BD (with a current depressive episode).

METHODS

Resting-state functional magnetic resonance imaging was obtained from 279 participants (95 BD patients, 107 UD patients and 77 health controls). Connectome gradients analysis was performed to explore the shared and diagnosis-specific gradient alterations in BD and UD. The Allen Human Brain Atlas data was used to explore the potential gene mechanisms of the gradient alterations.

RESULTS

BD and UD had shared hierarchical disorganisation, including downgrading and contraction from the unimodal sensory networks (vision and sensorimotor) to the transmodal cognitive networks (limbic, frontoparietal, dorsal attention, and default) (all P < 0.05, FDR corrected) in gradient 1 and gradient 2. The BD patients had specific connectome gradient dysfunction in the subcortical network. Moreover, the hierarchical disorganisation was closely correlated with profiles of gene expression specific to the neuroglial cells in the prefrontal cortex in BD and UD, while the most correlated gene ontology biological processes and function were concentrated in synaptic signalling, calcium ion binding, and transmembrane transporter activity.

CONCLUSION

These findings reveal the shared and diagnosis-specific neurobiological mechanism underlying BD and UD patients, which advances our understanding of the neuromechanisms of these disorders.

A preliminary composite of blood-based biomarkers to distinguish major depressive disorder and bipolar disorder in adolescents and adults

BACKGROUND

Since diagnosis of mood disorder heavily depends on signs and symptoms, emerging researches have been studying biomarkers with the attempt to improve diagnostic accuracy, but none of the findings have been broadly accepted. The purpose of the present study was to construct a preliminary diagnostic model to distinguish major depressive disorder (MDD) and bipolar disorder (BD) using potential commonly tested blood biomarkers.

METHODS

Information of 721 inpatients with an ICD-10 diagnosis of MDD or BD were collected from the electronic medical record system. Variables in the nomogram were selected by best subset selection method after a prior univariable screening, and then constructed using logistic regression with inclusion of the psychotropic medication use. The discrimination, calibration and internal validation of the nomogram were evaluated by the receiver operating characteristic curve (ROC), the calibration curve, cross validation and subset validation method.

RESULTS

The nomogram consisted of five variables, including age, eosinophil count, plasma concentrations of prolactin, total cholesterol, and low-density lipoprotein cholesterol. The model could discriminate between MDD and BD with an area under the ROC curve (AUC) of 0.858, with a sensitivity of 0.716 and a specificity of 0.890.

CONCLUSION

The comprehensive nomogram constructed by the present study can be convenient to distinguish MDD and BD since the incorporating variables were common indicators in clinical practice. It could help avoid misdiagnoses and improve prognosis of the patients.

Potential of Circulating miRNAs as Molecular Markers in Mood Disorders and Associated Suicidal Behavior

Mood disorders are the most prevalent psychiatric disorders associated with significant disability, morbidity, and mortality. The risk of suicide is associated with severe or mixed depressive episodes in patients with mood disorders. However, the risk of suicide increases with the severity of depressive episodes and is often presented with higher incidences in bipolar disorder (BD) patients than in patients with major depression (MDD). Biomarker study in neuropsychiatric disorders is critical for developing better treatment plans by facilitating more accurate diagnosis. At the same time, biomarker discovery also provides more objectivity to develop state-of-the-art personalized medicine with increased accuracy through clinical interventions. Recently, colinear changes in miRNA expression between brain and systemic circulation have added great interest in examining their potential as molecular markers in mental disorders, including MDD, BD, and suicidality. A present understanding of circulating miRNAs in body fluids implicates their role in managing neuropsychiatric conditions. Most notably, their use as prognostic and diagnostic markers and their potential role in treatment response have significantly advanced our knowledge base. The present review discusses circulatory miRNAs and their underlying possibilities to be used as a screening tool for assessing major psychiatric conditions, including MDD, BD, and suicidal behavior.