Simvastatin mitigates depressive-like behavior in ovariectomized rats: Possible role of NLRP3 inflammasome and estrogen receptors' modulation

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.

Role of NLRP3 Inflammasome in Post-Spinal-Cord-Injury Anxiety and Depression: Molecular Mechanisms and Therapeutic Implications

The majority of research on the long-term effects of spinal cord injury (SCI) has primarily focused on neuropathic pain (NP), psychological issues, and sensorimotor impairments. Among SCI patients, mood disorders, such as anxiety and depression, have been extensively studied. It has been found that chronic stress and NP have negative consequences and reduce the quality of life for individuals living with SCI. Our review examined both human and experimental evidence to explore the connection between mood changes following SCI and inflammatory pathways, with a specific focus on NLRP3 inflammasome signaling. We observed increased proinflammatory factors in the blood, as well as in the brain and spinal cord tissues of SCI models. The NLRP3 inflammasome plays a crucial role in various diseases by controlling the release of proinflammatory molecules like interleukin 1β (IL-1β) and IL-18. Dysregulation of the NLRP3 inflammasome in key brain regions associated with pain processing, such as the prefrontal cortex and hippocampus, contributes to the development of mood disorders following SCI. In this review, we summarized recent research on the expression and regulation of components related to NLRP3 inflammasome signaling in mood disorders following SCI. Finally, we discussed potential therapeutic approaches that target the NLRP3 inflammasome and regulate proinflammatory cytokines as a way to treat mood disorders following SCI.

NLRP3 inflammatory pathway. Can we unlock depression?

Depression holds the title of the largest contributor to worldwide disability, with the numbers expected to continue growing. Currently, there are neither reliable biomarkers for the diagnosis of the disease nor are the current medications sufficient for a lasting response in nearly half of patients. In this comprehensive review, we analyze the previously established pathophysiological models of the disease and how the interplay between NLRP3 inflammasome activation and depression might offer a unifying perspective. Adopting this inflammatory theory, we explain how NLRP3 inflammasome activation emerges as a pivotal contributor to depressive inflammation, substantiated by compelling evidence from both human studies and animal models. This inflammation is found in the central nervous system (CNS) neurons, astrocytes, and microglial cells. Remarkably, dysregulation of the NLRP3 inflammasome extends beyond the CNS boundaries and permeates into the enteric and peripheral immune systems, thereby altering the microbiota-gut-brain axis. The integrity of the brain blood barrier (BBB) and intestinal epithelial barrier (IEB) is also compromised by this inflammation. By emphasizing the central role of NLRP3 inflammasome activation in depression and its far-reaching implications, we go over each area with potential modulating mechanisms within the inflammasome pathway in hopes of finding new targets for more effective management of this debilitating condition.

Purinergic P2X7 receptor as a potential therapeutic target in depression

The elaborate mechanisms of depression have always been a research hotspot in recent years, and the pace of research has never ceased. The P2X7 receptor (P2X7R) belongs to one of the adenosine triphosphates (ATP)-gated cation channels that exist widely in brain tissues and play a prominent role in the regulation of depression-related pathology. To date, the role of purinergic P2X7R in the mechanisms underlying depression is not fully understood. In this review, we conclude that the purinergic receptor P2X7 is a potential therapeutic target for depression based on research results published over the past 5 years in Google Scholar and the National Library of Medicine (PubMed). Additionally, we introduced the functional characteristics of P2X7R and confirmed that excessive activation of P2X7R led to increased release of inflammatory cytokines, which eventually contributed to depression. Furthermore, the inhibition of P2X7R produced antidepressant-like effects in animal models of depression, further proving that P2X7R signalling mediates depression-like behaviours. Finally, we summarised related studies on drugs that exert antidepressant effects by regulating the expression of P2X7R. We hope that the conclusions of this review will provide information on the role of P2X7R in the neuropathophysiology of depression and novel therapeutic targets for the treatment of depression.

The association between polycyclic aromatic hydrocarbons exposure and neuropsychiatric manifestations in perimenopausal women: A cross-sectional study

BACKGROUND

Increasing evidence shows that polycyclic aromatic hydrocarbons (PAHs) exposure may adversely affect human health. However, the links between combined exposure to PAHs and neuropsychiatric manifestations in perimenopausal women remain unclear.

METHODS

To explore these relationships further, we used the data from the National Health and Nutrition Examination Surveys (NHANES) of the 2005-2012 cycles. After filtering, five hundred forty-seven perimenopausal women aged 45-55 years were included in our analysis. Eight PAHs metabolites were measured to represent PAHs exposure in the body. In our study, depression, sleep disorders, and frequent mental distress (FMD) were used to describe the neuropsychiatric manifestations. Because of the bivariate correlations among PAHs compounds, principal component analysis (PCA) was conducted to achieve the dimension reduction process of PAHs compounds. To figure out if there is a relationship between urinary PAH metabolites and outcomes, multiple logistic regression, restricted cubic splines (RCS), and the Bayesian kernel machine regression (BKMR) were used.

RESULTS

The findings showed that urinary PAHs concentrations in a certain range were related to neuropsychiatric manifestations. In detail, the results of logistic regressions, RCS, and BKMR all indicated that urinary PAHs were positively correlated with depression. In addition, the results of principal components regression and RCS showed associations between urinary PAHs and the risk of FMD or sleep disorders, respectively.

CONCLUSIONS

Exposure to PAHs was linked to neuropsychiatric manifestations in perimenopausal women, but more pertinent researches are required to understand the connections fully.

Estrogen plays an important role by influencing the NLRP3 inflammasome

The nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is an important part of the natural immune system that plays an important role in many diseases. Estrogen is a sex hormone that plays an important role in controlling reproduction and regulates many physiological and pathological processes. Recent studies have indicated that estrogen is associated with disease progression. Estrogen can ameliorate some diseases (e. g, sepsis, mood disturbances, cerebral ischemia, some hepatopathy, Parkinson's disease, amyotrophic lateral sclerosis, inflammatory bowel disease, spinal cord injury, multiple sclerosis, myocardial ischemia/reperfusion injury, osteoarthritis, and renal fibrosis) by inhibiting the NLRP3 inflammasome. Estrogen can also promote the development of diseases (e.g., ovarian endometriosis, dry eye disease, and systemic lupus erythematosus) by upregulating the NLRP3 inflammasome. In addition, estrogen has a dual effect on the development of cancers and asthma. However, the mechanism of these effects is not summarized. This article reviewed the progress in understanding the effects of estrogen on the NLRP3 inflammasome and its mechanisms in recent years to provide a theoretical basis for an in-depth study.

The pharmacological bases for repurposing statins in depression: a review of mechanistic studies

Statins are commonly prescribed medications widely investigated for their potential actions on the brain and mental health. Pre-clinical and clinical evidence suggests that statins may play a role in the treatment of depressive disorders, but only the latter has been systematically assessed. Thus, the physiopathological mechanisms underlying statins' putative antidepressant or depressogenic effects have not been established. This review aims to gather available evidence from mechanistic studies to strengthen the pharmacological basis for repurposing statins in depression. We used a broad, well-validated search strategy over three major databases (Pubmed/MEDLINE, Embase, PsychINFO) to retrieve any mechanistic study investigating statins' effects on depression. The systematic search yielded 8068 records, which were narrowed down to 77 relevant papers. The selected studies (some dealing with more than one bodily system) described several neuropsychopharmacological (44 studies), endocrine-metabolic (17 studies), cardiovascular (6 studies) and immunological (15 studies) mechanisms potentially contributing to the effects of statins on mood. Numerous articles highlighted the beneficial effect of statins on depression, particularly through positive actions on serotonergic neurotransmission, neurogenesis and neuroplasticity, hypothalamic-pituitary axis regulation and modulation of inflammation. The role of other mechanisms, especially the association between statins, lipid metabolism and worsening of depressive symptoms, appears more controversial. Overall, most mechanistic evidence supports an antidepressant activity for statins, likely mediated by a variety of intertwined processes involving several bodily systems. Further research in this area can benefit from measuring relevant biomarkers to inform the selection of patients most likely to respond to statins' antidepressant effects while also improving our understanding of the physiopathological basis of depression.

A novel pharmacological mechanism of anti-cancer drugs that induce pyroptosis

Pyroptosis is an inflammasome-induced lytic form of programmed cell death, and its main effect involves the release of inflammatory mediators when a cell dies, resulting in an inflammatory response in the body. The key to pyroptosis is the cleavage of GSDMD or other gasdermin families. Some drugs can cause cleavage GSDMD or other gasdermin members cause pyroptosis and suppress cancer growth and development. This review explores several drugs that may induce pyroptosis, thereby contributing to tumor treatment. Pyroptosis-inducing drugs, such as arsenic, platinum, and doxorubicin, were used originally in cancer treatment. Other pyroptosis-inducing drugs, such as metformin, dihydroartemisinin, and famotidine, were used to control blood glucose, treat malaria, and regulate blood lipid levels and are effective tumor treatments. By summarizing drug mechanisms, we provide a valuable basis for treating cancers by inducing pyroptosis. In future, the use of these drugs may contribute to new clinical treatments.

The NLRP3 inflammasome in depression: Potential mechanisms and therapies

Increasing evidence suggests that the failure of clinical antidepressants may be related with neuroinflammation. The NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome is an intracellular multiprotein complex, and has been considered as a key contributor to the development of neuroinflammation. Inhibition of NLRP3 inflammasome is an effective method for depression treatment. In this review, we summarized current researches highlighting the role of NLRP3 inflammasome in the pathology of depression. Firstly, we discussed NLRP3 inflammasome activation in patients with depression and animal models. Secondly, we outlined the possible mechanisms driving the activation of NLRP3 inflammasome. Thirdly, we discussed the pathogenetic role of NLRP3 inflammasome in depression. Finally, we overviewed the current and potential antidepressants targeting the NLRP3 inflammasome. Overall, the inhibition of NLRP3 inflammasome activation may be a potential therapeutic strategy for inflammation-related depression.

The Anti-Depressant Effects of Statins in Patients With Major Depression Post-Myocardial Infarction: An Updated Review 2022

Statins are the most commonly prescribed lipid-lowering agents in patients with cardiovascular disease, and more than half of the patients with cardiovascular disease have associated depressive symptoms, particularly post-myocardial infarction, which is a major trigger for depression. In our research, we tried to understand the anti-depressant effects of statins, the mechanisms, risks and benefits, and potential drug-drug interactions with anti-depressant medications. We reviewed all the relevant information from inception up to September 2022 regarding the anti-depressant effects of statins. The database used was PubMed, and the keywords were statins, major depression, post-myocardial infarction, and hydroxy methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors. We have screened each of the articles carefully, including both human and animal studies, and found a positive correlation between reduction in depressive symptoms with statin therapy as adjunctive treatment with conventional anti-depressants. In conclusion, statins as a monotherapy are not an effective treatment for depression post-myocardial infarction but are good add-on options along with standard therapy such as selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs). Statins are safe and have no serious drug-drug interactions with anti-depressants. We would like to encourage large-scale observational studies and further post-marketing surveillance to improve our knowledge regarding the effectiveness of statins in the treatment of depression.

Statins and Antidepressants: A Comprehensive Review and Clinical Outlook of the Risks and Benefits of Co-prescription (2022)

Antidepressants are the most prescribed medications in the United States, and the most frequently prescribed antidepressants are selective serotonin reuptake inhibitors (SSRIs) followed by serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), serotonin antagonist and reuptake inhibitors (SARIs), and norepinephrine-dopamine reuptake inhibitors (NDRI). On the other hand, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, also known as statins, are the most prescribed lipid-lowering medications, and because the majority of patients with cardiovascular disease (CVD) have depressive symptoms, it is essential to understand the possible drug-drug interactions these two classes of medications can have, their potential synergistic mechanisms, and possible risks. In our research, we tried to understand the facts and uncover any missing links regarding the potential risks and benefits of statins and antidepressant co-prescription in the current clinical scenario. We reviewed all the relevant information from inception up to October 2022 regarding the antidepressant and statin polypharmacy. The databases we used were PubMed and PubMed Central, and the 11 keywords were "statins," "SSRI," "SNRI," "selective serotonin reuptake inhibitors," "serotonin-norepinephrine reuptake inhibitors," "antidepressants," "HMG-CoA reductase inhibitors," "tricyclic antidepressants," "monoamine oxidase inhibitors," "serotonin antagonist and reuptake inhibitors," and "norepinephrine-dopamine reuptake inhibitors." We carefully screened each of the relevant articles, including animal and human studies. In our study, we concluded that co-prescription of statins and SSRIs/SNRIs was generally safe and should be encouraged due to the potential synergistic nature of their effects in patients with CVD and major depression, and caution is advised with all other classes of antidepressants. We would like to encourage the undertaking of large-scale observational studies and proactive postmarketing surveillance to improve our knowledge regarding this topic considering the immense clinical importance it holds by directly and indirectly affecting half the population worldwide.

Statins in depression: a repurposed medical treatment can provide novel insights in mental health

Depression has a large burden, but the development of new drugs for its treatment has proved difficult. Progresses in neuroscience have highlighted several physiopathological pathways, notably inflammatory and metabolic ones, likely involved in the genesis of depressive symptoms. A novel strategy proposes to repurpose established medical treatments of known safety and to investigate their potential antidepressant activity. Among numerous candidates, growing evidence suggests that statins may have a positive role in the treatment of depressive disorders, although some have raised concerns about possible depressogenic effects of these widely prescribed medications. This narrative review summarises relevant findings from translational studies implicating many interconnected neurobiological and neuropsychological, cardiovascular, endocrine-metabolic, and immunological mechanisms by which statins could influence mood. Also, the most recent clinical investigations on the effects of statins in depression are presented. Overall, the use of statins for the treatment of depressive symptoms cannot be recommended based on the available literature, though this might change as several larger, methodologically robust studies are being conducted. Nevertheless, statins can already be acknowledged as a driver of innovation in mental health, as they provide a novel perspective to the physical health of people with depression and for the development of more precise antidepressant treatments.

The effect of glucagon like peptide-1 receptor agonist on behavioral despair and anxiety-like behavior in ovariectomized rats: Modulation of BDNF/CREB, Nrf2 and lipocalin 2

Ovariectomized (OVX) rodents show behavioral despair and anxiety-like behaviors. Glucagon-like peptide-1 receptor agonists (GLP-1RA) possess neuroprotective effects by reducing oxidative stress and neuroinflammation, thereby preventing synaptic loss. The objective of the present study is to evaluate the effect of GLP-1RA, namely liraglutide, on emotional behaviors, and to identify the level of oxidative stress, neuroinflammation, and BDNF signaling in the hippocampus of OVX rats. Forty female young Wistar rats were divided into 5 groups: Control, Control+liraglutide treated, OVX, OVX+fluoxetine, and OVX+liraglutide (150 µg/kg for 15 days, sc). Open field test and elevated plus-maze test were used to evaluate behaviors that are suggestive of anxiety. A forced swimming test was used to evaluate behavioral despair. At the end of the experiments, blood glucose level and body weight gain were measured. The levels of BDNF, CREB, Nrf2, and lipocalin 2 in the hippocampal tissue were measured by ELISA. Malondialdehyde (MDA) and glutathione levels were also evaluated. Statistical analysis was conducted through ANOVA and Bonferroni tests. Seven weeks post-OVX rats exhibited high anxiety related behavior and behavioral despair in comparison with the control groups. These behavioral changes were associated with increased lipocalin 2 and MDA levels in rats. Moreover, BDNF, CREB, and Nrf2 levels decreased significantly in the hippocampus of OVX rats. Liraglutide treatment limited the reduction of BDNF and Nrf2 levels in the hippocampus, maintaining them at the control levels. Liraglutide treatment also prevented the symptoms of behavioral despair and anxiety related behavior. As the main finding of the study GLP-1RA reduced behavioral despair and anxiety level and this may be related to the preservation of BDNF/Nrf2 levels and the decrease in oxidative stress and lipocalin 2 levels in the hippocampus.

Microglia Involves in the Immune Inflammatory Response of Poststroke Depression: A Review of Evidence

Poststroke depression (PSD) does not exist before and occurs after the stroke. PSD can appear shortly after the onset of stroke or be observed in the weeks and months after the acute or subacute phase of stroke. The pathogenesis of PSD is unclear, resulting in poor treatment effects. With research advancement, immunoactive cells in the central nervous system, particularly microglia, play a role in the occurrence and development of PSD. Microglia affects the homeostasis of the central nervous system through various factors, leading to the occurrence of depression. The research progress of microglia in PSD has been summarized to review the evidence regarding the pathogenesis and treatment target of PSD in the future.

Sex differences in stress-induced alcohol intake: a review of preclinical studies focused on amygdala and inflammatory pathways

Clinical studies suggest that women are more likely than men to relapse to alcohol drinking in response to stress; however, the mechanisms underlying this sex difference are not well understood. A number of preclinical behavioral models have been used to study stress-induced alcohol intake. Here, we review paradigms used to study effects of stress on alcohol intake in rodents, focusing on findings relevant to sex differences. To date, studies of sex differences in stress-induced alcohol drinking have been somewhat limited; however, there is evidence that amygdala-centered circuits contribute to effects of stress on alcohol seeking. In addition, we present an overview of inflammatory pathways leading to microglial activation that may contribute to alcohol-dependent behaviors. We propose that sex differences in neuronal function and inflammatory signaling in circuits centered on the amygdala are involved in sex-dependent effects on stress-induced alcohol seeking and suggest that this is an important area for future studies.

NLRP3-Dependent Pyroptosis: A Candidate Therapeutic Target for Depression

Depression, a major public health problem, imposes a significant economic burden on society. Recent studies have gradually unveiled the important role of neuroinflammation in the pathogenesis of depression. Pyroptosis, a programmed cell death mediated by Gasdermins (GSDMs), is also considered to be an inflammatory cell death with links to inflammation. Pyroptosis has emerged as an important pathological mechanism in several neurological diseases and has been found to be involved in several neuroinflammatory-related diseases. A variety of chemical agents and natural products have been found to be capable of exerting therapeutic effects by modulating pyroptosis. Studies have shown that depression is closely associated with pyroptosis and the induced neuroinflammation of relevant brain regions, such as the hippocampus, amygdala, prefrontal cortex neurons, etc., in which the nucleotide-binding oligomerization domain-like receptor protein 3 inflammasome plays a crucial role. This article provides a timely review of recent findings on the activation and regulation of pyroptosis in relation to depression.

Saikosaponin d Alleviates Liver Fibrosis by Negatively Regulating the ROS/NLRP3 Inflammasome Through Activating the ERβ Pathway

Background and aims: Saikosaponin d (SSd) has a steroidal structure and significant anti-inflammatory effects. The purpose of this study was to explore the mechanism underlying SSd’s inhibitory effects on liver fibrosis.

Methods: Wild-type and estrogen receptor knockout (ERKO) mice were treated with CCl₄ to establish liver fibrosis mouse models. The effects of SSd on hepatic fibrogenesis were studied in these mouse models. Hepatic stellate cells (HSCs) were activated by H₂O₂ to investigate the potential molecular mechanisms. The establishment of the models and the degrees of inflammation and liver tissue fibrosis were evaluated by detecting changes in serum liver enzymes and liver histopathology. The expression of α-SMA and TGF-β1 was determined by immunohistochemistry. The expression and significance of NLRP3 inflammasome proteins were explored by RT-PCR and Western blotting analyses. The mitochondrial ROS-related indexes were evaluated by MitoSOX Red.

Results: In wild-type and ERKO mice treated with CCl₄, the fluorescence expression of mitochondrial ROS was up-regulated, while the mitochondrial membrane potential and ATP content were decreased, suggesting that the mitochondria were damaged. In addition, the expression of NLRP3 inflammatory bodies and fibrosis markers (α-SMA, TGF-β, TIMP-1, MMP-2, and Vimentin) in liver tissue increased. Furthermore, the above indexes showed the same expression trend in activated HSCs. In addition, the peripheral serum ALT and AST levels increased in CCl₄-induced liver injury model mice. And HE staining showed a large number of inflammatory cell infiltration in the liver of model mice. Picric acid-Sirius staining and Masson staining showed that there was significant collagen fibrous tissue deposition in mice liver sections. IHC and WB detection confirmed that the expression of α-SMA and TGF-β1 increased. Liver fibrosis scores were also elevated. Then, after SSd intervention, the expression of ROS in wild-type mice and αERKO mice decreased, mitochondrial membrane potential recovered, ATP level increased, NLRP3 inflammasome and fibrosis indexes decreased, liver enzyme levels decreased, and liver pathology showed liver inflammation. The damage and collagen deposition were significantly relieved, the expression of α-SMA and TGF-β1 was decreased, and the fibrosis score was also decreased. More importantly, the effect of SSd in alleviating liver injury and liver fibrosis had no effect on βERKO mice.

Conclusion: SSd alleviated liver fibrosis by negatively regulating the ROS/NLRP3 inflammasome through activating the ERβ pathway. By establishing liver fibrosis models using wild-type and ERKO mice, we demonstrated that SSd could alleviate liver fibrosis by inhibiting the ROS/NLRP3 inflammasome axis through activating the ERβ pathway.

Novel Pharmacological Approaches to the Treatment of Depression

Major depressive disorder is one of the most prevalent mental health disorders. Monoamine-based antidepressants were the first drugs developed to treat major depressive disorder. More recently, ketamine and other analogues were introduced as fast-acting antidepressants. Unfortunately, currently available therapeutics are inadequate; lack of efficacy, adverse effects, and risks leave patients with limited treatment options. Efforts are now focused on understanding the etiology of depression and identifying novel targets for pharmacological treatment. In this review, we discuss promising novel pharmacological targets for the treatment of major depressive disorder. Targeting receptors including N-methyl-D-aspartate receptors, peroxisome proliferator-activated receptors, G-protein-coupled receptor 39, metabotropic glutamate receptors, galanin and opioid receptors has potential antidepressant effects. Compounds targeting biological processes: inflammation, the hypothalamic-pituitary-adrenal axis, the cholesterol biosynthesis pathway, and gut microbiota have also shown therapeutic potential. Additionally, natural products including plants, herbs, and fatty acids improved depressive symptoms and behaviors. In this review, a brief history of clinically available antidepressants will be provided, with a primary focus on novel pharmaceutical approaches with promising antidepressant effects in preclinical and clinical studies.