A Review of Research on the Association between Neuron-Astrocyte Signaling Processes and Depressive Symptoms

Novel insight into astrocyte-mediated gliotransmission modulates the synaptic plasticity in major depressive disorder

Major depressive disorder (MDD) is a form of glial cell-based synaptic dysfunction disease in which glial cells interact closely with neuronal synapses and perform synaptic information processing. Glial cells, particularly astrocytes, are active components of the brain and are responsible for synaptic activity through the release gliotransmitters. A reduced density of astrocytes and astrocyte dysfunction have both been identified the brains of patients with MDD. Furthermore, gliotransmission, i.e., active information transfer mediated by gliotransmitters between astrocytes and neurons, is thought to be involved in the pathogenesis of MDD. However, the mechanism by which astrocyte-mediated gliotransmission contributes to depression remains unknown. This review therefore summarizes the alterations in astrocytes in MDD, including astrocyte marker, connexin 43 (Cx43) expression, Cx43 gap junctions, and Cx43 hemichannels, and describes the regulatory mechanisms of astrocytes involved in synaptic plasticity. Additionally, we investigate the mechanisms acting of the glutamatergic, gamma-aminobutyric acidergic, and purinergic systems that modulate synaptic function and the antidepressant mechanisms of the related receptor antagonists. Further, we summarize the roles of glutamate, gamma-aminobutyric acid, d-serine, and adenosine triphosphate in depression, providing a basis for the identification of diagnostic and therapeutic targets for MDD.

Exploring the Potential of Saffron as a Therapeutic Agent in Depression Treatment: A Comparative Review

Depression is a significant mental health challenge globally. While traditional antidepressants are effective, they often have unwanted side effects. Saffron, a natural spice derived from Crocus sativus L., has emerged as a potential alternative therapy for depression. Researchers have found that its components such as crocin, crocetin, and safranal have been found to mitigate depressive symptoms through neurotransmitter regulation, anti-inflammatory effects, and neuroprotection. Clinical trials suggest that the effectiveness of saffron in treating mild to moderate depression is comparable to that of standard medications, and animal studies support these results, showing behavioral improvements with saffron treatment. Saffron is particularly appealing due to its safety and lower incidence of side effects, making it suitable for those sensitive to conventional drugs. Additionally, its antioxidant properties may offer further health benefits. However, challenges such as determining the appropriate dosage, prohibitive cost, and the limited availability of quality saffron need to be addressed. Most research on saffron's efficacy is short-term; thus, long-term studies are essential to understand its full therapeutic potential and ongoing antidepressant effects. While saffron is safe in terms of its culinary value, higher therapeutic doses require careful monitoring for drug interactions and side effects. In summary, saffron represents a promising direction in depression treatment, with benefits potentially matching those of standard treatments and a better safety profile. However, further research is necessary to establish clear guidelines for its use, optimize dosing, and assess long-term outcomes. Saffron offers a natural treatment path for depression, but its use must be controlled and supported by scientific evidence.

Role of Glial Cells in Neuronal Function, Mood Disorders, and Drug Addiction

Mood disorders and substance use disorder (SUD) are of immense medical and social concern. Although significant progress on neuronal involvement in mood and reward circuitries has been achieved, it is only relatively recently that the role of glia in these disorders has attracted attention. Detailed understanding of the glial functions in these devastating diseases could offer novel interventions. Here, following a brief review of circuitries involved in mood regulation and reward perception, the specific contributions of neurotrophic factors, neuroinflammation, and gut microbiota to these diseases are highlighted. In this context, the role of specific glial cells (e.g., microglia, astroglia, oligodendrocytes, and synantocytes) on phenotypic manifestation of mood disorders or SUD are emphasized. In addition, use of this knowledge in the potential development of novel therapeutics is touched upon.

Exploring the transformative impact of traditional Chinese medicine on depression: Insights from animal models

Depression, a prevalent and complex mental health condition, presents a significant global health burden. Depression is one of the most frequent mental disorders; deaths from it account for 14.3% of people worldwide. In recent years, the integration of complementary and alternative medicine, including traditional Chinese medicine (TCM), has gained attention as a potential avenue for addressing depression. This comprehensive review critically assesses the efficacy of TCM interventions in alleviating depressive symptoms. An in-depth look at different research studies, clinical trials, and meta-analyses is used in this review to look into how TCM practices like herbal formulations, acupuncture, and mind-body practices work. The review looks at the quality of the evidence, the rigor of the methods, and any possible flaws in the current studies. This gives us an idea of where TCM stands right now in terms of treating depression. This comprehensive review aims to assess the efficacy of TCM interventions in alleviating depressive symptoms. In order to learn more about their possible healing effects, the study also looks into how different types of TCM work, such as herbal formulas, acupuncture, and mind-body practices.

Identification of the antidepressant effect of electroconvulsive stimulation-related genes in hippocampal astrocyte

Major depressive disorder (MDD) remains a significant global health concern, with limited and slow efficacy of existing antidepressants. Electroconvulsive therapy (ECT) has superior and immediate efficacy for MDD, but its action mechanism remains elusive. Therefore, the elucidation of the action mechanism of ECT is expected to lead to the development of novel antidepressants with superior and immediate efficacy. Recent studies suggest a potential role of hippocampal astrocyte in MDD and ECT. Hence, we investigated antidepressant effect of electroconvulsive stimulation (ECS), an animal model of ECT, -related genes in hippocampal astrocyte with a mouse model of MDD, in which corticosterone (CORT)-induced depression-like behaviors were recovered by ECS. In this model, both of CORT-induced depression-like behaviors and the reduction of hippocampal astrocyte were recovered by ECS. Following it, astrocytes were isolated from the hippocampus of this model and RNA-seq was performed with these isolated astrocytes. Interestingly, gene expression patterns altered by CORT were reversed by ECS. Additionally, cell proliferation-related signaling pathways were inhibited by CORT and recovered by ECS. Finally, serum and glucocorticoid kinase-1 (SGK1), a multi-functional protein kinase, was identified as a candidate gene reciprocally regulated by CORT and ECS in hippocampal astrocyte. Our findings suggest a potential role of SGK1 in the antidepressant effect of ECS via the regulation of the proliferation of astrocyte and provide new insights into the involvement of hippocampal astrocyte in MDD and ECT. Targeting SGK1 may offer a novel approach to the development of new antidepressants which can replicate superior and immediate efficacy of ECT.

Does decreased autophagy and dysregulation of LC3A in astrocytes play a role in major depressive disorder?

Astrocytic dysfunction contributes to the molecular pathogenesis of major depressive disorder (MDD). However, the astrocytic subtype that mainly contributes to MDD etiology and whether dysregulated autophagy in astrocytes is associated with MDD remain unknown. Using a single-nucleus RNA sequencing (snRNA-seq) atlas, three astrocyte subtypes were identified in MDD, while C2 State-1Q astrocytes showed aberrant changes in both cell proportion and most differentially expressed genes compared with other subtypes. Moreover, autophagy pathways were commonly inhibited in astrocytes in the prefrontal cortices (PFCs) of patients with MDD, especially in C2 State-1Q astrocytes. Furthermore, by integrating snRNA-seq and bulk transcriptomic data, we found significant reductions in LC3A expression levels in the PFC region of CUMS-induced depressed mice, as well as in postmortem PFC tissues and peripheral blood samples from patients with MDD. These results were further validated by qPCR using whole-blood samples from patients with MDD and healthy controls. Finally, LC3A expression in the whole blood of patients with MDD was negatively associated with the severity of depressive symptoms. Overall, our results underscore autophagy inhibition in PFC astrocytes as a common molecular characteristic in MDD and might reveal a novel potential diagnostic marker LC3A.