Patchouli alcohol ameliorates depression-like behaviors through inhibiting NLRP3-mediated neuroinflammation in male stress-exposed mice

Natural products that alleviate depression: The putative role of autophagy

Major depressive disorder (MDD) is a common mental disorder that severely disrupts psychosocial function and decreases the quality of life. Although the pathophysiological mechanism underlying MDD is complex and remains unclear, emerging evidence suggests that autophagy dysfunction plays a role in MDD occurrence and progression. Natural products serve as a major source of drug discovery and exert tremendous potential in developing antidepressants. Recently published reports are paying more attention on the autophagy regulatory effect of antidepressant natural products. In this review, we comprehensively discuss the abnormal changes occurred in multiple autophagy stages in MDD patients, and animal and cell models of depression. Importantly, we emphasize the regulatory mechanism of antidepressant natural products on disturbed autophagy, including monomeric compounds, bioactive components, crude extracts, and traditional Chinese medicine formulae. Our comprehensive review suggests that enhancing autophagy might be a novel approach for MDD treatment, and natural products restore autophagy homeostasis to facilitate the renovation of mitochondria, impede neuroinflammation, and enhance neuroplasticity, thereby alleviating depression.

Microglial priming by IFN-γ involves STAT1-mediated activation of the NLRP3 inflammasome

BACKGROUND

Inflammatory and immune responses in the brain that contribute to various neuropsychiatric disorders may begin as microglial "priming". Interferon (IFN)-γ is known to cause microglial priming, but the mechanism is unclear.

METHODS

We examined the effects of IFN-γ on gene expression, microglial activation, inflammatory and immune responses and activity of the NLRP3 inflammasome in primary microglia and in the brains of mice.

RESULTS

Our results showed that treating microglial cultures with IFN-γ induced a hedgehog-like morphology and upregulated markers of microglial activation (CD86, CD11b) and pro-inflammatory molecules (IL-1β, IL-6, TNF-α, iNOS), while downregulating markers of microglial homeostasis (CX3CR1, CD200R1), anti-inflammatory molecules (MCR1, Arg-1) and neurotrophic factors (IGF-1, BDNF). IFN-γ also upregulated markers of NLRP3 inflammasome activation (NLRP3, caspase-1, gasdermin D, IL-18). This particular transcriptional profiling makes IFN-γ-primed microglia with exaggerated responses upon lipopolysaccharide (LPS) stimulation. The level of NLRP3, caspase-1, gasdermin D, IL-1β, IL-18, TNF-α and iNOS in microglia cultures treated with both IFN-γ and LPS were highest than with either one alone. Injecting IFN-γ into the lateral ventricle of mice induced similar morphological and functional changes in hippocampal microglia as in primary microglial cultures. The effects of IFN-γ on NLRP3 inflammasome and microglia from cultures or hippocampus were abolished when STAT1 was inhibited using fludarabin. Injecting mice with IFN-γ alone or together with LPS induced anxiety- and depression-like behaviors and impaired hippocampus-dependent spatial memory; these effects were mitigated by fludarabin.

CONCLUSIONS

IFN-γ primes microglia by activating STAT1, which upregulates genes that activate the NLRP3 inflammasome. Inhibiting the IFN-γ/STAT1 axis may be a way to treat neurodegenerative diseases and psychiatric disorders that involve microglial priming.

Microglial NLRP3 inflammasome-mediated neuroinflammation and therapeutic strategies in depression

Previous studies have demonstrated a bidirectional relationship between inflammation and depression. Activation of the nucleotide-binding oligomerization domain, leucine-rich repeat, and NLR family pyrin domain-containing 3 (NLRP3) inflammasomes is closely related to the pathogenesis of various neurological diseases. In patients with major depressive disorder, NLRP3 inflammasome levels are significantly elevated. Understanding the role that NLRP3 inflammasome-mediated neuroinflammation plays in the pathogenesis of depression may be beneficial for future therapeutic strategies. In this review, we aimed to elucidate the mechanisms that lead to the activation of the NLRP3 inflammasome in depression as well as to provide insight into therapeutic strategies that target the NLRP3 inflammasome. Moreover, we outlined various therapeutic strategies that target the NLRP3 inflammasome, including NLRP3 inflammatory pathway inhibitors, natural compounds, and other therapeutic compounds that have been shown to be effective in treating depression. Additionally, we summarized the application of NLRP3 inflammasome inhibitors in clinical trials related to depression. Currently, there is a scarcity of clinical trials dedicated to investigating the applications of NLRP3 inflammasome inhibitors in depression treatment. The modulation of NLRP3 inflammasomes in microglia holds promise for the management of depression. Further investigations are necessary to ascertain the efficacy and safety of these therapeutic approaches as potential novel antidepressant treatments.

Lactate: A New Target for Brain Disorders

Lactate in the brain is produced endogenously and exogenously. The primary functional cells that produce lactate in the brain are astrocytes. Astrocytes release lactate to act on neurons, thereby affecting neuronal function, through a process known as the astrocyte-neuron shuttle. Lactate affects microglial function as well and inhibits microglia-mediated neuroinflammation. Lactate also provides energy, acts as a signaling molecule, and promotes neurogenesis. This article summarizes the role of lactate in cells, animals, and humans. Lactate is a protective molecule against stress in healthy organisms and in the early stages of brain disorders. Thus, lactate may be a potential therapeutic target for brain disorders. Further research on the role of lactate in microglia may have great prospects. This article provides a new perspective and research direction for the study of lacate in brain disorders.

The Antiviral Potential of Perilla frutescens: Advances and Perspectives

Viruses pose a significant threat to human health, causing widespread diseases and impacting the global economy. Perilla frutescens, a traditional medicine and food homologous plant, is well known for its antiviral properties. This systematic review examines the antiviral potential of Perilla frutescens, including its antiviral activity, chemical structure and pharmacological parameters. Utilizing bioinformatics analysis, we revealed the correlation between Perilla frutescens and antiviral activity, identified overlaps between Perilla frutescens target genes and virus-related genes, and explored related signaling pathways. Moreover, a classified summary of the active components of Perilla frutescens, focusing on compounds associated with antiviral activity, provides important clues for optimizing the antiviral drug development of Perilla frutescens. Our findings indicate that Perilla frutescens showed a strong antiviral effect, and its active ingredients can effectively inhibit the replication and spread of a variety of viruses in this review. The antiviral mechanisms of Perilla frutescens may involve several pathways, including enhanced immune function, modulation of inflammatory responses, and inhibition of key enzyme activities such as viral replicase. These results underscore the potential antiviral application of Perilla frutescens as a natural plant and provide important implications for the development of new antiviral drugs.

Targeting inflammasome complexes as a novel therapeutic strategy for mood disorders

INTRODUCTION

Inflammasome complexes, especially NLRP3, have gained great attention as a potential therapeutic target in mood disorders. NLRP3 triggers a caspase 1-dependent release of the inflammatory cytokines IL-1β and IL-18, and seems to interact with purinergic and kynurenine pathways, all of which are implicated in mood disorders development and progression.

AREAS COVERED

Emerging evidence supports NLRP3 inflammasome as a promising pharmacological target for mood disorders. We discussed the available evidence from animal models and human studies and provided a reflection on drawbacks and perspectives for this novel target.

EXPERT OPINION

Several studies have supported the involvement of NLRP3 inflammasome in MDD. However, most of the evidence comes from animal models. The role of NLRP3 inflammasome in BD as well as its anti-manic properties is not very clear and requires further exploration. There is evidence of anti-manic effects of P2×R7 antagonists associated with reduction in the brain levels of IL-1β and TNF-α in a murine model of mania. The involvement of other NLRP3 inflammasome expressing cells besides microglia, like astrocytes, and of other inflammasome complexes in mood disorders also deserves further investigation. Preclinical and clinical characterization of NLRP3 and other inflammasomes in mood disorders is needed before considering translational approaches, including clinical trials.

A Comprehensive Review of Essential Oils and Their Pharmacological Activities in Neurological Disorders: Exploring Neuroprotective Potential

Numerous studies have demonstrated essential oils' diverse chemical compositions and pharmacological properties encompassing antinociceptive, anxiolytic-like, and anticonvulsant activities, among other notable effects. The utilization of essential oils, whether inhaled, orally ingested, or applied topically, has commonly been employed as adjunctive therapy for individuals experiencing anxiety, insomnia, convulsions, pain, and cognitive impairment. The utilization of synthetic medications in the treatment of various disorders and symptoms is associated with a wide array of negative consequences. Consequently, numerous research groups across the globe have been prompted to explore the efficacy of natural alternatives such as essential oils. This review provides a comprehensive overview of the existing literature on the pharmacological properties of essential oils and their derived compounds and the underlying mechanisms responsible for these observed effects. The primary emphasis is on essential oils and their constituents, specifically targeting the nervous system and exhibiting significant potential in treating neurodegenerative disorders. The current state of research in this field is characterized by its preliminary nature, highlighting the necessity for a more comprehensive overlook of the therapeutic advantages of essential oils and their components. Integrating essential oils into conventional therapies can enhance the effectiveness of comprehensive treatment regimens for neurodegenerative diseases, offering a more holistic approach to addressing the multifaceted nature of these conditions.

Adult hippocampal neurogenesis: pharmacological mechanisms of antidepressant active ingredients in traditional Chinese medicine

Depression is characterized by prominent indicators and manifestations, such as anhedonia, which refers to the inability to experience pleasure, and persistent feelings of hopelessness. In clinical practice, the primary treatment approach involves the utilization of selective serotonin reuptake inhibitors (SSRIs) and related pharmacological interventions. Nevertheless, it is crucial to recognize that these agents are associated with significant adverse effects. Traditional Chinese medicine (TCM) adopts a multifaceted approach, targeting diverse components, multiple targets, and various channels of action. TCM has potential antidepressant effects. Anomalies in adult hippocampal neurogenesis (AHN) constitute a pivotal factor in the pathology of depression, with the regulation of AHN emerging as a potential key measure to intervene in the pathogenesis and progression of this condition. This comprehensive review presented an overview of the pharmacological mechanisms underlying the antidepressant effects of active ingredients found in TCM. Through examination of recent studies, we explored how these ingredients modulated AHN. Furthermore, we critically assessed the current limitations of research in this domain and proposed novel strategies for preclinical investigation and clinical applications in the treatment of depression in future.

How Oxidative Stress Induces Depression?

Depression increasingly affects a wide range and a large number of people worldwide, both physically and psychologically, which makes it a social problem requiring prompt attention and management. Accumulating clinical and animal studies have provided us with substantial insights of disease pathogenesis, especially central monoamine deficiency, which considerably promotes antidepressant research and clinical treatment. The first-line antidepressants mainly target the monoamine system, whose drawbacks mainly include slow action and treatment resistant. The novel antidepressant esketamine, targeting on central glutamatergic system, rapidly and robustly alleviates depression (including treatment-resistant depression), whose efficiency is shadowed by potential addictive and psychotomimetic side effects. Thus, exploring novel depression pathogenesis is necessary, for seeking more safe and effective therapeutic methods. Emerging evidence has revealed vital involvement of oxidative stress (OS) in depression, which inspires us to pursue antioxidant pathway for depression prevention and treatment. Fully uncovering the underlying mechanisms of OS-induced depression is the first step towards the avenue, thus we summarize and expound possible downstream pathways of OS, including mitochondrial impairment and related ATP deficiency, neuroinflammation, central glutamate excitotoxicity, brain-derived neurotrophic factor/tyrosine receptor kinase B dysfunction and serotonin deficiency, the microbiota-gut-brain axis disturbance and hypothalamic-pituitary-adrenocortical axis dysregulation. We also elaborate on the intricate interactions between the multiple aspects, and molecular mechanisms mediating the interplay. Through reviewing the related research progress in the field, we hope to depict an integral overview of how OS induces depression, in order to provide fresh ideas and novel targets for the final goal of efficient treatment of the disease.