Cytokines mediated inflammation and decreased neurogenesis in animal models of depression

Pathogenesis of HIV-associated depression: contributing factors and underlying mechanisms

Cumulative evidence indicates that compared to HIV negative individuals, people living with HIV (PLWH) have a higher likelihood of developing depression, anxiety, and cognitive disorders. Depression, which is known to be a persistent and overwhelming feeling of sadness accompanied by a loss of interest in usual activities, is one of the most common mental illnesses encountered during HIV infection. Experts believe that several factors such as neuroinflammation, life stressors, lack of sleep, poor nutritional state, opportunistic infections and comorbidities, and HIV medications are contributing factors favoring the development of depression in PLWH. However, the fundamental mechanisms which underlie the involvement of these factors in the emergence of depression in the context of HIV remain poorly explored. Past researches describing the role of one or two of the preceding factors do exist; however, very few articles tackle this important topic while considering the several different putative causative factors comprehensively in the particular context of HIV infection. Herein, we elaborate on the factors currently understood to be responsible for the development of depression, and discuss the particular fundamental mechanisms whereby each factor may result in the outcome of depression. We believe that the understanding of these factors and of their underlying mechanisms is essential for the development of future therapeutic interventions to alleviate the burden of depression commonly seen in PLWH, and therefore facilitate the development of strategies to improve their overall quality of life.

Microglial-Biomimetic Memantine-Loaded Polydopamine Nanomedicines for Alleviating Depression

Depression is a common psychiatric disorder, and monoamine-based antidepressants as first-line therapy remain ineffective in some patients. The synergistic modulation of neuroinflammation and neuroplasticity could be a major strategy for treating depression. In this study, an inflammation-targeted microglial biomimetic system, PDA-Mem@M, is reported for treating depression. Microglial membrane-coated nanoparticles penetrate the blood-brain barrier and facilitate microglial targeting. Subsequently, owing to the excellent free radical-scavenging capacity, PDA-Mem@M attenuate the brain inflammatory microenvironment. After on-demand release from the nanoparticles, memantine increases the expression of brain-derived neurotrophic factors and reverses the loss of synaptic dendritic spines. Further, in vivo studies demonstrate that PDA-Mem@M effectively alleviate depression-like behaviors to a greater extent than memantine or polydopamine nanoparticles (PDA) monotherapy. This synergistic strategy, with satisfactory biosafety and strong anti-inflammatory and synaptic plasticity restoration effects, is conducive to advances in depression therapy.

Exploring the pathophysiological influence of heme oxygenase-1 on neuroinflammation and depression: A study of phytotherapeutic-based modulation

BACKGROUND

The heme oxygenase (HO) system plays a significant role in neuroprotection and reduction of neuroinflammation and neurodegeneration. The system, via isoforms HO-1 and HO-2, regulates cellular redox balance. HO-1, an antioxidant defense enzyme, is highlighted due to its association with depression, characterized by heightened neuroinflammation and impaired oxidative stress responses.

METHODOLOGY

We observed the pathophysiology of HO-1 and phytochemicals as its modulator. We explored Science Direct, Scopus, and PubMed for a comprehensive literature review. Bibliometric and temporal trend analysis were done using VOSviewer.

RESULTS

Several phytochemicals can potentially alleviate neuroinflammation and oxidative stress-induced depressive symptoms. These effects result from inhibiting the MAPK and NK-κB pathways - both implicated in the overproduction of pro-inflammatory factors - and from the upregulation of HO-1 expression mediated by Nrf2. Bibliometric and temporal trend analysis further validates these associations.

CONCLUSION

In summary, our findings suggest that antidepressant agents can mitigate neuroinflammation and depressive disorder pathogenesis via the upregulation of HO-1 expression. These agents suppress pro-inflammatory mediators and depressive-like symptoms, demonstrating that HO-1 plays a significant role in the neuroinflammatory process and the development of depression.

Long-term intake of thermo-induced oxidized oil results in anxiety-like and depression-like behaviors: involvement of microglia and astrocytes

Frequent consumption of fried foods has been strongly associated with a higher risk of anxiety and depression, particularly among young individuals. The existing evidence has indicated that acrylamide produced from starchy foods at high temperatures can induce anxious behavior. However, there is limited research on the nerve damage caused by thermo-induced oxidized oil (TIOO). In this study, we conducted behavioral tests on mice and found that prolonged consumption of TIOO led to significant anxiety behavior and a tendency toward depression. TIOO primarily induced these two emotional disorders by affecting the differentiation of microglia, the level of inflammatory factors, the activation of astrocytes, and glutamate circulation in brain tissue. By promoting the over-differentiation of microglia into M1 microglia, TIOO disrupted their differentiation balance, resulting in an up-regulation of inflammatory factors (IL-1β, IL-6, TNF-α, NOS2) in M1 microglia and a down-regulation of neuroprotective factors IL-4/IL-10 in M2 microglia, leading to nerve damage. Moreover, TIOO activated astrocytes, accelerating their proliferation and causing GFAP precipitation, which damaged astrocytes. Meanwhile, TIOO stimulates the secretion of the BDNF and reduces the level of the glutamate receptor GLT-1 in astrocytes, leading to a disorder in the glutamate-glutamine cycle, further exacerbating nerve damage. In conclusion, this study suggests that long-term intake of thermo-induced oxidized oil can trigger symptoms of anxiety and depression.

Association of dietary overall antioxidant intake with all-cause and cause-specific mortality among adults with depression: evidence from NHANES 2005-2018

Higher intakes of individual antioxidants such as vitamins A, C, and E have been linked to mortality in the general population, but the association of overall antioxidant intake with mortality especially in depressed adults remains unclear. We aimed to investigate whether the dietary overall antioxidant intake is associated with all-cause and cause-specific mortality among depressed adults. This study included 3051 US adults with depression, who participated in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018. Patient Health Questionnaire-9 (PHQ-9) was used to define depression and evaluate depression severity. The dietary antioxidant quality score (DAQS) and dietary antioxidant index (DAI) were calculated based on the intakes of vitamins A, C, and E, zinc, selenium, and magnesium. A higher DAQS and DAI were significantly associated with lower depression scores (PHQ-9) (all P-trend < 0.05). For individual antioxidants, significant negative associations of vitamins A and E with all-cause mortality were observed. For overall antioxidant intake, the DAQS and DAI were inversely associated with all-cause and cancer mortality. Compared with participants in the lowest categories of DAQS and DAI, the corresponding HRs (95% CIs) in the highest categories were 0.63 (0.42-0.93) and 0.70 (0.49-0.98) for all-cause mortality and 0.39 (0.17-0.87) and 0.43 (0.21-0.88) for cancer mortality, respectively. The overall dietary antioxidant intake was beneficially associated with all-cause and cancer mortality in depressed adults. These findings suggest that comprehensive dietary antioxidant intake may improve depressive symptoms and lower mortality risk among adults with depression.

Obesity and Depression: Common Link and Possible Targets

Depression is among the main causes of disability, and its protracted manifestations could make it even harder to treat metabolic diseases. Obesity is linked to episodes of depression, which is closely correlated to abdominal adiposity and impaired food quality. The present review is aimed at studying possible links between obesity and depression along with targets to disrupt it. Research output in Pubmed and Scopus were referred for writing this manuscript. Obesity and depression are related, with the greater propensity of depressed people to gain weight, resulting in poor dietary decisions and a sedentary lifestyle. Adipokines, which include adiponectin, resistin, and leptin are secretory products of the adipose tissue. These adipokines are now being studied to learn more about the connection underlying obesity and depression. Ghrelin, a gut hormone, controls both obesity and depression. Additionally, elevated ghrelin levels result in anxiolytic and antidepressant-like effects. The gut microbiota influences the metabolic functionalities of a person, like caloric processing from indigestible nutritional compounds and storage in fatty tissue, that exposes an individual to obesity, and gut microorganisms might connect to the CNS through interconnecting pathways, including neurological, endocrine, and immunological signalling systems. The alteration of brain activity caused by gut bacteria has been related to depressive episodes. Monoamines, including dopamine, serotonin, and norepinephrine, have been widely believed to have a function in emotions and appetite control. Emotional signals stimulate arcuate neurons in the hypothalamus that are directly implicated in mood regulation and eating. The peptide hormone GLP-1(glucagon-like peptide- 1) seems to have a beneficial role as a medical regulator of defective neuroinflammation, neurogenesis, synaptic dysfunction, and neurotransmitter secretion discrepancy in the depressive brain. The gut microbiota might have its action in mood and cognition regulation, in addition to its traditional involvement in GI function regulation. This review addressed the concept that obesity-related low-grade mild inflammation in the brain contributes to chronic depression and cognitive impairments.

The hypothalamic steroidogenic pathway mediates susceptibility to inflammation-evoked depression in female mice

BACKGROUND

Depression is two-to-three times more frequent among women. The hypothalamus, a sexually dimorphic area, has been implicated in the pathophysiology of depression. Neuroinflammation-induced hypothalamic dysfunction underlies behaviors associated with depression. The lipopolysaccharide (LPS)-induced mouse model of depression has been well-validated in numerous laboratories, including our own, and is widely used to investigate the relationship between neuroinflammation and depression. However, the sex-specific differences in metabolic alterations underlying depression-associated hypothalamic neuroinflammation remain unknown.

METHODS

Here, we employed the LPS-induced mouse model of depression to investigate hypothalamic metabolic changes in both male and female mice using a metabolomics approach. Through bioinformatics analysis, we confirmed the molecular pathways and biological processes associated with the identified metabolites. Furthermore, we employed quantitative real-time PCR, enzyme-linked immunosorbent assay, western blotting, and pharmacological interventions to further elucidate the underlying mechanisms.

RESULTS

A total of 124 and 61 differential metabolites (DMs) were detected in male and female mice with depressive-like behavior, respectively, compared to their respective sex-matched control groups. Moreover, a comparison between female and male model mice identified 37 DMs. We capitalized on biochemical clustering and functional enrichment analyses to define the major metabolic changes in these DMs. More than 55% of the DMs clustered into lipids and lipid-like molecules, and an imbalance in lipids metabolism was presented in the hypothalamus. Furthermore, steroidogenic pathway was confirmed as a potential sex-specific pathway in the hypothalamus of female mice with depression. Pregnenolone, an upstream component of the steroid hormone biosynthesis pathway, was downregulated in female mice with depressive-like phenotypes but not in males and had considerable relevance to depressive-like behaviors in females. Moreover, exogenous pregnenolone infusion reversed depressive-like behaviors in female mice with depression. The 5α-reductase type I (SRD5A1), a steroidogenic hub enzyme involved in pregnenolone metabolism, was increased in the hypothalamus of female mice with depression. Its inhibition increased hypothalamic pregnenolone levels and ameliorated depressive-like behaviors in female mice with depression.

CONCLUSIONS

Our study findings demonstrate a marked sexual dimorphism at the metabolic level in depression, particularly in hypothalamic steroidogenic metabolism, identifying a potential sex-specific pathway in female mice with depressive-like behaviors.

Altered IL-3 and lipocalin-2 levels are associated with the pathophysiology of major depressive disorder: a case-control study

BACKGROUND

Major Depressive Disorder (MDD) is a common mental ailment and is the primary reason for disability. It manifests a severe impact on moods, thoughts, and physical health. At present, this disorder has become a concern in the field of public health. Alteration of neurochemicals is thought to be involved in the pathogenesis of many psychiatric disorders. Therefore, we aimed to evaluate serum IL-3 and lipocalin-2 in MDD patients and healthy controls (HCs).

METHOD

We included a total of 376 participants in this study. Among them, 196 were MDD patients, and 180 were age-sex-matched HCs. MDD patients were recruited from the Psychiatry Department of Bangabandhu Sheikh Mujib Medical University (BSMMU), but the controls were from different parts of Dhaka. All study participants were evaluated by a psychiatrist using the DSM-5 criteria. To assess the severity of the depression, we used the Hamilton depression (Ham-D) rating scale. Serum IL-3 and lipocalin-2 levels were measured using commercially available enzyme-linked immune-sorbent assay kits (ELISA kits).

RESULTS

According to this study, we observed elevated serum levels of IL-3 (1,024.73 ± 29.84 pg/mL) and reduced levels of serum lipocalin-2 (29.019 ± 2.073 ng/mL) in MDD patients compared to HCs (911.11 ± 20.55 pg/mL and 48.065 ± 3.583 ng/mL, respectively). No associations between serum levels of IL-3 and lipocalin-2 and depression severity were observed in patients.

CONCLUSIONS

According to the present findings, alterations of serum IL-3 and lipocalin might be associated with the pathogenesis of MDD. These results support that altered serum neurochemicals can serve as early risk assessment markers for depression. Further interventional studies are recommended for a better understanding of the role of IL-3 and lipocalin-2 in the pathophysiology of depression.

Itaconate: A promising precursor for treatment of neuroinflammation associated depression

Neuroinflammation triggers the production of inflammatory factors, influences neuron generation and synaptic plasticity, thus playing an important role in the pathogenesis of depression and becoming an important direction of depression prevention and treatment. Itaconate is a metabolite secreted by macrophages in immunomodulatory responses, that has potent immunomodulatory effects and has been proven to exert anti-inflammatory effects in a variety of diseases. Microglia are mononuclear macrophages that reside in the central nervous system (CNS), and may be the source of endogenous itaconate in the brain. Itaconate can directly inhibit succinate dehydrogenase (SDH), reduce the production of NOD-like receptor thermal protein domain associated protein 3 (NLRP3), activate nuclear factor erythroid-2 related factor 2 (Nrf2), and block glycolysis, and thereby improving the depressive symptoms associated with the above mechanisms. Notably, itaconate also indirectly ameliorates the depressive symptoms associated with some inflammatory diseases. With the optimization of the structure and the development of new delivery systems, the application value and therapeutic potential of itaconate have been significantly improved. Dimethyl itaconate (DI) and 4-octyl itaconate (4-OI), cell-permeable derivatives of itaconate, are more suitable for crossing the blood-brain barrier (BBB), exhibiting therapeutic effects in the research of multiple diseases. This article provides an overview of the immunomodulatory effects of itaconate and its potential therapeutic efficacy in inflammatory depression, focusing on the promising application of itaconate as a precursor of antidepressants.

Short-term memory impairment following recovery from systemic inflammation induced by lipopolysaccharide in mice

The relationship between neuroinflammation and mental disorders has been recognized and investigated for over 30 years. Diseases of systemic or peripheral inflammation, such as sepsis, peritonitis, and infection, are associated with increased risk of mental disorders with neuroinflammation. To elucidate the pathogenesis, systemic administration of lipopolysaccharide (LPS) in mice is often used. LPS-injected mice exhibit behavioral abnormalities with glial activation. However, these studies are unlikely to recapitulate the clinical pathophysiology of human patients, as most studies focus on the acute inflammatory response with systemic symptoms occurring within 24 h of LPS injection. In this study, we focus on the effects of LPS on behavioral abnormalities following recovery from systemic symptoms and investigate the mechanisms of pathogenesis. Several behavioral tests were performed in LPS-injected mice, and to assess neuroinflammation, the time course of the morphological change and expression of inflammatory factors in neurons, astrocytes, and microglia were investigated. At 7 days post-LPS injection, mice exhibited short-term memory impairment accompanied by the suppression of neuronal activity and increases in morphologically immature spines. Glial cells were transiently activated in the hippocampus concomitant with upregulation of the microglial phagocytosis marker CD68 3 days after injection. Here we show that transient glial cell activation in the acute response phase affects neuronal activity and behavior following recovery from systemic symptoms. These findings provide novel insights for studies using the LPS-induced inflammation model and that will contribute to the development of treatments for mental disorders of this etiology.

Folate and Its Significance in Depressive Disorders and Suicidality: A Comprehensive Narrative Review

Depressive disorders pose significant challenges to global public health, necessitating effective prevention and management strategies. Notably, the occurrence of suicide frequently coincides with depressive episodes. Suicide is as a paramount global health concern that demands efficacious preventive strategies. Current psychiatric approaches heavily rely on pharmacological interventions but have had limited success in addressing the global burden of mental health issues. Suboptimal nutrition, with its impact on the neuroendocrine system, has been implicated in the underlying pathology of depressive disorders. Folate, a group of water-soluble compounds, plays a crucial role in various central nervous system functions. Depressed individuals often exhibit low levels of serum and red blood cell folate. Multiple studies and systematic reviews have investigated the efficacy of folic acid and its derivative, L-methylfolate, which can cross the blood-brain barrier, as stand-alone or adjunct therapies for depression. Although findings have been mixed, the available evidence generally supports the use of these compounds in depressed individuals. Recent studies have established links between the one-carbon cycle, folate-homocysteine balance, immune system function, glutamate excitation via NMDA (N-methyl-D-aspartate) receptors, and gut microbiome eubiosis in mood regulation. These findings provide insights into the complex neurobiological mechanisms underlying the effects of folate and related compounds in depression. Through a comprehensive review of the existing literature, this study aims to advance our understanding of the therapeutic potential of folic acid and related compounds in depression treatment. It also seeks to explore their role in addressing suicidal tendencies and shed light on the neurobiological mechanisms involved, leveraging the latest discoveries in depression research.

Natural antioxidant formula ameliorates lipopolysaccharide-induced impairment of hippocampal neurogenesis and contextual fear memory through suppression of neuroinflammation in rats

This study investigated the ameliorating effects of a natural antioxidant formula (NAF) consisting of Ginkgo biloba leaf extract, docosahexaenoic acid/eicosapentaenoic acid, ferulic acid, flaxseed oil, vitamin E, and vitamin B12 on a lipopolysaccharide (LPS)-induced cognitive dysfunction model in rats. Six-week-old rats received a diet containing 0.5% (w/w) NAF for 38 days from Day 1, and LPS (1 mg/kg body weight) was administered intraperitoneally once daily on Days 8 and 10. On Day 11, LPS alone increased interleukin-1β and tumor necrosis factor-α in the hippocampus and cerebral cortex and the numbers of M1-type microglia/macrophages and GFAP+ reactive astrocytes in the hilus of the hippocampal dentate gyrus. NAF treatment decreased brain proinflammatory cytokine levels and increased the number of M2-type microglia/macrophages. During Days 34-38, LPS alone impaired fear memory acquisition and the extinction learning process, and NAF facilitated fear extinction learning. On Day 38, LPS alone decreased the number of type-3 neural progenitor cells in the hippocampal neurogenic niche, and NAF restored the number of type-3 neural progenitor cells and increased the numbers of both immature granule cells in the neurogenic niche and reelin+ hilar interneurons. Thus, NAF exhibited anti-inflammatory effects and ameliorated LPS-induced adverse effects on hippocampal neurogenesis and fear memory learning, possibly through amplification of reelin signaling by hilar interneurons. These results suggest that neuroinflammation is a key factor in the development of LPS-induced impairment of fear memory learning, and supplementation with NAF in the present study helped to prevent hippocampal neurogenesis and disruptive neurobehaviors caused by neuroinflammation.

Identifying circulating biomarkers for major depressive disorder

Objective

To date, the current diagnosis of major depressive disorder (MDD) still depends on clinical symptomatologic criteria, misdiagnosis and ineffective treatment are common. The study aimed to explore circulating biomarkers for MDD diagnosis.

Methods

A high-throughput antibody array technology was utilized to detect 440 circulating cytokines in eight MDD patients and eight age-and gender-matched healthy controls. LASSO regression was conducted for MDD-related characteristic proteins selection. Enzyme-linked immunosorbent assay (ELISA) was used to validate the characteristic proteins in 40 MDD patients and 40 healthy controls. Receiver operating characteristic (ROC) curve was employed to evaluate the diagnostic values of characteristic proteins for discriminating MDD patients from healthy controls. Correlations between the levels of characteristic proteins and depression severity (HAMD-17 scores) were evaluated using linear regression.

Results

The levels of 59 proteins were found aberrant in MDD patients compared with healthy controls. LASSO regression found six MDD-related characteristic proteins including insulin, CD40L, CD155, Lipocalin-2, HGF and LIGHT. ROC curve analysis showed that the area under curve (AUC) values of six characteristic proteins were more than 0.85 in discriminating patients with MDD from healthy controls. Furthermore, significant relationship was found between the levels of insulin, CD155, Lipocalin-2, HGF, LIGHT and HAMD-17 scores in MDD group.

Conclusion

These results suggested that six characteristic proteins screened from 59 proteins differential in MDD may hold promise as diagnostic biomarkers in discriminating patients with MDD. Among six characteristic proteins, insulin, CD155, Lipocalin-2, HGF and LIGHT might be useful to estimate the severity of depressive symptoms.

An updated review on prediction and preventive treatment of post-stroke depression

INTRODUCTION

Post-stroke depression (PSD), one of the most common complications following stroke, affects approximately one-third of stroke patients and is significantly associated with increased disability and mortality as well as decreased quality of life, which makes it an important public health concern. Treatment of PSD significantly ameliorates depressive symptoms and improves the prognosis of stroke.

AREAS COVERED

The authors discuss the critical aspects of the clinical application of prediction and preventive treatment of PSD. Then, the authors update the biological factors associated with the onset of PSD. Furthermore, they summarize the recent progress in pharmacological preventive treatment in clinical trials and propose potential treatment targets. The authors also discuss the current roadblocks in the preventive treatment of PSD. Finally, the authors put postulate potential directions for future studies so as to discover accurate predictors and provide individualized preventive treatment.

EXPERT OPINION

Sorting out high-risk PSD patients using reliable predictors will greatly assist PSD management. Indeed, some predictors not only predict the incidence of PSD but also predict prognosis, which indicates that they might also aid the development of an individualized treatment scheme. Preventive application of antidepressants may also be considered.

Protective effect of metformin on methotrexate induced reduction of rat hippocampal neural stem cells and neurogenesis

Adult neurogenesis is a process in which the adult neural stem cells produce newborn neurons that are implicated in terms of learning and memory. Methotrexate (MTX) is a chemotherapeutic drug, which has a negative effect on memory and hippocampal neurogenesis in animal models. Metformin is an antidiabetic drug with strong antioxidant capacities. We found that metformin ameliorates MTX induced deteriorations of memory and hippocampal neurogenesis in adult rats. In this study, we focus to investigate neural stem cells, biomarkers of apoptosis, and the protein for synaptogenesis, which involves in the transcription factors of the hippocampus in rats that received metformin and MTX. Male Sprague-Dawley rats were composed of control, MTX, metformin, and MTX+metformin groups. MTX (75 mg/kg, i.v.) was given on days 7 and 14, whereas metformin (200 mg/kg, i.p.) was given for 14 days. Hippocampal neural stem cells in the subgranular zone (SGZ) were quantified using immunofluorescence staining of Sox2 and nestin. Protein expression including PSD95, Casepase-3, Bax, Bcl-2, CREB, and pCREB were determined using Western blotting. MTX-treated rats displayed decreases in Sox2 and nestin-positive cells in the SGZ. Increases in Caspase-3 and Bax levels and decreases in PSD95, Bcl-2, CREB, and pCREB protein expressions in the hippocampus were also detected. However, these negative impacts of MTX were ameliorated by co-treatment with metformin. These consequences postulate that metformin has a potential to increase neural stem cells, synaptic plasticity, decreased apoptotic activities, and transcription factors, resulting in upregulation of hippocampal neurogenesis in MTX-treated rats.

TFOS Lifestyle: Impact of lifestyle challenges on the ocular surface

Many factors in the domains of mental, physical, and social health have been associated with various ocular surface diseases, with most of the focus centered on aspects of dry eye disease (DED). Regarding mental health factors, several cross-sectional studies have noted associations between depression and anxiety, and medications used to treat these disorders, and DED symptoms. Sleep disorders (both involving quality and quantity of sleep) have also been associated with DED symptoms. Under the domain of physical health, several factors have been linked to meibomian gland abnormalities, including obesity and face mask wear. Cross-sectional studies have also linked chronic pain conditions, specifically migraine, chronic pain syndrome and fibromyalgia, to DED, principally focusing on DED symptoms. A systematic review and meta-analysis reviewed available data and concluded that various chronic pain conditions increased the risk of DED (variably defined), with odds ratios ranging from 1.60 to 2.16. However, heterogeneity was noted, highlighting the need for additional studies examining the impact of chronic pain on DED signs and subtype (evaporative versus aqueous deficient). With respect to societal factors, tobacco use has been most closely linked to tear instability, cocaine to decreased corneal sensitivity, and alcohol to tear film disturbances and DED symptoms.

Non-steroidal anti-inflammatory drug target gene associations with major depressive disorders: a Mendelian randomisation study integrating GWAS, eQTL and mQTL Data

Previous observational studies reported associations between non-steroidal anti-inflammatory drugs (NSAIDs) and major depressive disorder (MDD), however, these associations are often inconsistent and underlying biological mechanisms are still poorly understood. We conducted a two-sample Mendelian randomisation (MR) study to examine relationships between genetic variants and NSAID target gene expression or DNA methylation (DNAm) using publicly available expression, methylation quantitative trait loci (eQTL or mQTL) data and genetic variant-disease associations from genome-wide association studies (GWAS of MDD). We also assessed drug exposure using gene expression and DNAm levels of NSAID targets as proxies. Genetic variants were robustly adjusted for multiple comparisons related to gene expression, DNAm was used as MR instrumental variables and GWAS statistics of MDD as the outcome. A 1-standard deviation (SD) lower expression of NEU1 in blood was related to lower C-reactive protein (CRP) levels of -0.215 mg/L (95% confidence interval (CI): 0.128-0.426) and a decreased risk of MDD (odds ratio [OR] = 0.806; 95% CI: 0.735-0.885; p = 5.36 × 10^-6). A concordant direction of association was also observed for NEU1 DNAm levels in blood and a risk of MDD (OR = 0.886; 95% CI: 0.836-0.939; p = 4.71 × 10^-5). Further, the genetic variants associated with MDD were mediated by NEU1 expression via DNAm (β = -0.519; 95% CI: -0.717 to -0.320256; p = 3.16 × 10^-7). We did not observe causal relationships between inflammatory genetic marker estimations and MDD risk. Yet, we identified a concordant association of NEU1 messenger RNA and an adverse direction of association of higher NEU1 DNAm with MDD risk. These results warrant increased pharmacovigilance and further in vivo or in vitro studies to investigate NEU1 inhibitors or supplements for MDD.

Anti-inflammatory properties of commonly used psychiatric drugs

Mental health and neurodevelopmental disorders are extremely common across the lifespan and are characterized by a complicated range of symptoms that affect wellbeing. There are relatively few drugs available that target disease mechanisms for any of these disorders. Instead, therapeutics are focused on symptoms and syndromes, largely driven by neurotransmitter hypotheses, such as serotonin or dopamine hypotheses of depression. Emerging evidence suggests that maternal inflammation during pregnancy plays a key role in neurodevelopmental disorders, and inflammation can influence mental health expression across the lifespan. It is now recognized that commonly used psychiatric drugs (anti-depressants, anti-psychotics, and mood stabilizers) have anti-inflammatory properties. In this review, we bring together the human evidence regarding the anti-inflammatory mechanisms for these main classes of psychiatric drugs across a broad range of mental health disorders. All three classes of drugs showed evidence of decreasing levels of pro-inflammatory cytokines, particularly IL-6 and TNF-α, while increasing the levels of the anti-inflammatory cytokine, IL-10. Some studies also showed evidence of reduced inflammatory signaling via nuclear factor- (NF-)κB and signal transducer and activator of transcription (STAT) pathways. As researchers, clinicians, and patients become increasingly aware of the role of inflammation in brain health, it is reassuring that these psychiatric drugs may also abrogate this inflammation, in addition to their effects on neurotransmission. Further studies are required to determine whether inflammation is a driver of disease pathogenesis, and therefore should be a therapeutic target in future clinical trials.

Amelioration of lipopolysaccharides-induced impairment of fear memory acquisition by alpha-glycosyl isoquercitrin through suppression of neuroinflammation in rats

This study investigated the role of neuroinflammation in a lipopolysaccharides (LPS)-induced cognitive dysfunction model in rats using an antioxidant, α-glycosyl isoquercitrin (AGIQ). Six-week-old rats were dietary treated with 0.5% (w/w) AGIQ for 38 days, and LPS at 1 mg/kg body weight was administered intraperitoneally once daily on Days 8 and 10. On Day 11, LPS alone increased or tended to increase interleukin-1β and tumor necrosis factor-α in the hippocampus and cerebral cortex. Immunohistochemically, LPS alone increased the number of Iba1⁺ and CD68⁺ microglia, and GFAP⁺ astrocytes in the hilus of the hippocampal dentate gyrus (DG). AGIQ treatment decreased or tended to decrease brain proinflammatory cytokine levels and the number of CD68⁺ microglia in the DG hilus. In the contextual fear conditioning test during Day 34 and Day 38, LPS alone impaired fear memory acquisition, and AGIQ tended to recover this impairment. On Day 38, LPS alone decreased the number of DCX⁺ cells in the neurogenic niche, and AGIQ increased the numbers of PCNA⁺ cells in the subgranular zone and CALB2⁺ hilar interneurons. Additionally, LPS alone decreased or tended to decrease the number of synaptic plasticity-related FOS⁺ and COX2⁺ granule cells and AGIQ recovered them. The results suggest that LPS administration induced acute neuroinflammation and subsequent impairment of fear memory acquisition caused by suppressed synaptic plasticity of newborn granule cells following disruptive neurogenesis. In contrast, AGIQ exhibited anti-inflammatory effects and ameliorated LPS-induced adverse effects. These results suggest that neuroinflammation is a key factor in the development of LPS-induced impairment of fear memory acquisition.

Epigenetics in depression and gut-brain axis: A molecular crosstalk

Gut-brain axis is a dynamic, complex, and bidirectional communication network between the gut and brain. Changes in the microbiota-gut-brain axis are responsible for developing various metabolic, neurodegenerative, and neuropsychiatric disorders. According to clinical and preclinical findings, the gut microbiota is a significant regulator of the gut-brain axis. In addition to interacting with intestinal cells and the enteric nervous system, it has been discovered that microbes in the gut can modify the central nervous system through metabolic and neuroendocrine pathways. The metabolites of the gut microbiome can modulate a number of diseases by inducing epigenetic alteration through DNA methylation, histone modification, and non-coding RNA-associated gene silencing. Short-chain fatty acids, especially butyrate, are well-known histone deacetylases inhibitors. Similarly, other microbial metabolites such as folate, choline, and trimethylamine-N-oxide also regulate epigenetics mechanisms. Furthermore, various studies have revealed the potential role of microbiome dysbiosis and epigenetics in the pathophysiology of depression. Hence, in this review, we have highlighted the role of gut dysbiosis in epigenetic regulation, causal interaction between host epigenetic modification and the gut microbiome in depression and suggest microbiome and epigenome as a possible target for diagnosis, prevention, and treatment of depression.

Neurobiological mechanisms of mood disorders: Stress vulnerability and resilience

Stress is an important factor in the development of several human pathologies. The response of rodents and humans to stress depends on many factors; some people and rodents develop stress-related mood disorders, such as depression and anxiety in humans, depression-like and anxiety-like behavior in mice and rats, while others report no new psychological symptoms in response to chronic or acute stress, and are considered susceptible and resilient to stress, respectively. Resilience is defined as the ability to thrive in the face of adversity and is a learned process that can help protect against occupational stressors and mental illnesses. There is growing interest in the underlying mechanisms involved in resilience and vulnerability to depression caused by stress, and some studies have demonstrated that individual variability in the way animals and humans respond to stress depends on several mechanisms, such as oxidative stress, neuronal plasticity, immunology and genetic factors, among others not discussed in this review, this review provides a general overview about this mechanism.

A randomized, double-blind, placebo-controlled, 12-week trial of vitamin D augmentation in major depressive disorder associated with vitamin D deficiency

BACKGROUND

Randomized controlled trials (RCTs) of vitamin D (VitD) supplementation for depression have yielded inconsistent results. We conducted the first RCT of VitD supplementation with multipoint serum 25(OH)D assessments in major depressive disorder (MDD) patients with concurrent severe VitD deficiency.

METHODS

We randomized antidepressant-free depressed adults with mean baseline 25(OH)D of 11.5 ng/ml to VitD (60,000 IU every 5 days; n = 31) or placebo (n = 28) for 12 weeks. All patients also received escitalopram (10-20 mg/day). Patients were rated at baseline and at the end of weeks 4, 8, and 12. Serum 25(OH)D was estimated at baseline, week 8, and week 12.

RESULTS

In an intent-to-treat analysis, mean Hamilton Depression Scale scores dropped from 25.7 to 5.7 and from 25.8 to 5.0 in VitD and placebo groups, respectively (primary outcome; P = 0.92). VitD and placebo groups did not differ on other objective and subjective ratings of depression, or on global ratings. Similar findings characterized completer analyses. No significant correlations were observed between 25(OH)D levels and depression ratings across the course of the study. Importantly, endpoint escitalopram doses were 4 mg/day higher in placebo than in VitD patients, and 4 mg/day higher in VitD deficient than in VitD sufficient patients.

LIMITATIONS

A ceiling effect with escitalopram may have prevented the discovery of benefits with VitD supplementation.

CONCLUSIONS

VitD supplementation does not improve antidepressant outcomes with flexibly dosed escitalopram. VitD deficient depressed patients may require higher antidepressant doses to experience benefits similar to those whose deficiency is corrected by VitD supplementation.

Grape seed extract effects on hippocampal neurogenesis, synaptogenesis and dark neurons production in old mice. Can this extract improve learning and memory in aged animals?

BACKGROUND

During the elderly, hippocampal neurogenesis and synaptogenesis reduce and dark neurons (DNs) increase, leading to cognitive impairment. It is believed that natural products can protect the neural cells and system by protecting from damages or promoting regeneration. Therefore, the effects of grape seed extract (GSE) on the hippocampus of aged mice were investigated in this study.

METHODS

twelve old mice were divided into two groups of control and GSE. Animals in the GSE group received 300 mg/kg of GSE for eight weeks via gavage. At the end of treatment, cognition performance was evaluated by Morris water maze (MWM) and passive avoidance tests. Hippocampal neurogenesis, synaptogenesis and DNs production were evaluated with immunohistochemistry and histological evaluations on 5-micron coronal tissue sections.

RESULTS

The hippocampal mean number of double cortin positive cells (DCX+) per unit area, as well as synaptophysin expression in the GSE group, were significantly higher than the control group (p < 0.01). The frequency of DNs in the GSE group was lower than the control group (p < 0.05). Behavioral tests showed that GSE improves memory and learning performance.

CONCLUSION

Consuming GSE in the elderly can potentially alleviate the age-related reduction of hippocampal neurogenesis and synaptogenesis. It is also able to decrease hippocampal DNs production and increase memory and learning.

Neuro-Inflammaging and Psychopathological Distress

Inflammaging is a low degree of chronic and systemic tissue inflammation associated with aging, and is intimately linked to pro-inflammatory mediators. These substances are involved in the pathogenesis of chronic inflammatory diseases and related psychopathological symptoms. When inflammation and aging affect the brain, we use the term neuro-inflammaging. In this review, we focused on the neuro-inflammatory process typical of advanced ages and the related psychopathological symptoms, with particular attention to understanding the immune-pathogenetic mechanisms involved and the potential use of immunomodulatory drugs in the control of clinical psychological signs. Inflammation and CNS were demonstrated being intimately linked in the neuro-inflammatory loop. IL-1, IL-6, TNF-a, COX and PGE are only partially responsible. BBB permeability and the consequent oxidative stress resulting from tissue damage make the rest. Some authors elaborated the "theory of cytokine-induced depression". Inflammation has a crucial role in the onset symptoms of psychopathological diseases as it is capable of altering the metabolism of biogenic monoamines involved in their pathogenesis. In recent years, NSAIDs as an adjunct therapy in the treatment of relevant psychopathological disorders associated with chronic inflammatory conditions demonstrated their efficacy. Additionally, novel molecules have been studied, such as adalimumab, infliximab, and etanercept showing antidepressant and anxiolytic promising results. However, we are only at the beginning of a new era characterized by the use of biological drugs for the treatment of inflammatory and autoimmune diseases, and this paper aims to stimulate future studies in such a direction.

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.

Inflammatory markers and incident depression: Evidence in a population-based prospective study

The association between pro-inflammatory cytokines and depression is widely acknowledged. However, longitudinal data that show they lead to depression are few. In a community-based sample of older individuals (n = 2761, ages = 55-98 y) in the Singapore Longitudinal Ageing Study (SLAS), we analyzed the associations between inflammatory markers (CRP, IL6, TNFα, and inflammation risk score) and depression (defined as the presence of depressive symptoms, depression history or treatment). Cross-sectional analysis showed that CRP, IL-6 and TNFα were significantly associated with depression at baseline. Longitudinal analysis controlling for a host of potentially confounding risk factors and initial depression revealed that IL-6, TNFα, and inflammation risk score were associated with elevated risk of depression at follow-ups. However, there was no significant association between CRP and subsequent depression after adjusting for sociodemographic, lifestyles and inflammatory medical condition variables. In summary, this prospective study shows that inflammation predicts depression in older adults, and suggests that the heterogeneous findings among studies may be due to differences in study population characteristics, depression, inflammatory markers, and the extent of adjusting for confounders.

Animal Models for Neuroinflammation and Potential Treatment Methods

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic disease of unknown etiology and without effective treatment options. The onset of ME/CFS is often associated with neuroinflammation following bacterial or viral infection. A positron emission tomography imaging study revealed that the degree of neuroinflammation was correlated with the severity of several symptoms in patients with ME/CFS. In animal studies, lipopolysaccharide- and polyinosinic-polycytidylic acid-induced models are thought to mimic the pathological features of ME/CFS and provoke neuroinflammation, characterized by increased levels of proinflammatory cytokines and activation of microglia. In this review, we described the anti-inflammatory effects of three compounds on neuroinflammatory responses utilizing animal models. The findings of the included studies suggest that anti-inflammatory substances may be used as effective therapies to ameliorate disease symptoms in patients with ME/CFS.

A Reciprocal Link Between Gut Microbiota, Inflammation and Depression: A Place for Probiotics?

Depression is a severe mental disorder that places a significant economic burden on public health. The reciprocal link between the trillions of bacteria in the gut, the microbiota, and depression is a controversial topic in neuroscience research and has drawn the attention of public interest and press coverage in recent years. Mounting pieces of evidence shed light on the role of the gut microbiota in depression, which is suggested to involve immune, endocrine, and neural pathways that are the main components of the microbiota-gut-brain axis. The gut microbiota play major roles in brain development and physiology and ultimately behavior. The bidirectional communication between the gut microbiota and brain function has been extensively explored in animal models of depression and clinical research in humans. Certain gut microbiota strains have been associated with the pathophysiology of depression. Therefore, oral intake of probiotics, the beneficial living bacteria and yeast, may represent a therapeutic approach for depression treatment. In this review, we summarize the findings describing the possible links between the gut microbiota and depression, focusing mainly on the inflammatory markers and sex hormones. By discussing preclinical and clinical studies on probiotics as a supplementary therapy for depression, we suggest that probiotics may be beneficial in alleviating depressive symptoms, possibly through immune modulation. Still, further comprehensive studies are required to draw a more solid conclusion regarding the efficacy of probiotics and their mechanisms of action.

Keel bone damage affects behavioral and physiological responses related to stress and fear in two strains of laying hens

Keel bone damage (KBD) is more prevalent in alternative laying hen housing systems than in conventional cages, and its incidence differs from strain to strain. However, the information of KBD in Lindian chickens, a native Chinese strain, is limited. To investigate the effect of KBD on fearfulness and physiological indicators of stress in Lindian chickens and commercial laying hens, a total of two hundred 25-wk-old chickens (100 Hy-line Brown and 100 Lindian chickens) were studied for 7 wk. The birds were housed in furnished cages with 10 birds per cage for each strain. At 32-wk of age, the birds in each strain were divided into normal (NK), deviated (DK), and fractured (FK) hens according to the keel bone status. Ten birds in each keel bone status per strain were subsequently selected to collect blood for the determination of stress and fear-related indicators, including corticosterone, serotonin, interleukin-1β, and interleukin-6, and measure fear responses, including novel object test (NOT), human approach test (HAT), and tonic immobility (TI) test. The results showed that egg production was lower and the incidence of keel bone fractures was higher in Lindian chickens than in Hy-line Brown hens (P < 0.05). Lindian chickens showed a significantly increased whole blood serotonin content, NOT-latency, HAT-score, and TI induction times (P < 0.05) and decreased serum interleukin-6 content and TI-duration (P < 0.05) compared with Hy-line Brown hens. Additionally, FK hens had significantly elevated whole blood corticosterone, serum interleukin-1β and interleukin-6 levels, TI-duration, and NOT-latency (P < 0.05), and a reduced whole blood serotonin content (P < 0.05) compared with NK and DK hens. Our results indicated that KBD affected stress and fear responses, and this impact was mainly reflected by FK hens compared with NK and DK hens. We suggest that keel bone fractures are the main factor impairing hen welfare. Besides, the incidence of keel bone fractures and stress and fear responses of Lindian chickens are more severe than Hy-line Brown laying hens, indicating that the strain type can affect the health and welfare of laying hens.

Scientific Validation of Human Neurosphere Assays for Developmental Neurotoxicity Evaluation

There is a call for a paradigm shift in developmental neurotoxicity (DNT) evaluation, which demands the implementation of faster, more cost-efficient, and human-relevant test systems than current in vivo guideline studies. Under the umbrella of the Organisation for Economic Co-operation and Development (OECD), a guidance document is currently being prepared that instructs on the regulatory use of a DNT in vitro battery (DNT IVB) for fit-for-purpose applications. One crucial issue for OECD application of methods is validation, which for new approach methods (NAMs) requires novel approaches. Here, mechanistic information previously identified in vivo, as well as reported neurodevelopmental adversities in response to disturbances on the cellular and tissue level, are of central importance. In this study, we scientifically validate the Neurosphere Assay, which is based on human primary neural progenitor cells (hNPCs) and an integral part of the DNT IVB. It assesses neurodevelopmental key events (KEs) like NPC proliferation (NPC1ab), radial glia cell migration (NPC2a), neuronal differentiation (NPC3), neurite outgrowth (NPC4), oligodendrocyte differentiation (NPC5), and thyroid hormone-dependent oligodendrocyte maturation (NPC6). In addition, we extend our work from the hNPCs to human induced pluripotent stem cell-derived NPCs (hiNPCs) for the NPC proliferation (iNPC1ab) and radial glia assays (iNPC2a). The validation process we report for the endpoints studied with the Neurosphere Assays is based on 1) describing the relevance of the respective endpoints for brain development, 2) the confirmation of the cell type-specific morphologies observed in vitro, 3) expressions of cell type-specific markers consistent with those morphologies, 4) appropriate anticipated responses to physiological pertinent signaling stimuli and 5) alterations in specific in vitro endpoints upon challenges with confirmed DNT compounds. With these strong mechanistic underpinnings, we posit that the Neurosphere Assay as an integral part of the DNT in vitro screening battery is well poised for DNT evaluation for regulatory purposes.

Is (R)-ketamine a Potential Therapeutic Agent for Treatment-Resistant Depression with Less Detrimental Side Effects? A Review of Molecular Mechanisms Underlying Ketamine and its Enantiomers

Approximately one-third of individuals with major depressive disorder are resistant to conventional antidepressants (i.e., monoamine-based therapies), and, even among respondents, a proper therapeutic effect may require weeks of treatment. Ketamine, a racemic mixture of the two enantiomers, (R)-ketamine and (S)-ketamine, is an N-methyl-d-aspartate receptor (NMDAR) antagonist and has been shown to have rapid-acting antidepressant properties in patients with treatment-resistant depression (TRD). Although (R)-ketamine has a lower affinity for NMDAR, it presents greater potency and longer-lasting antidepressant properties, with no major side effects, than racemic ketamine or (S)-ketamine in preclinical findings. Thereby, ketamine and its enantiomers have not only an antagonistic effect on NMDAR but also a strong synaptogenic-modulatory effect, which is impaired in TRD pathophysiology. In this review, we summarize the current evidence regarding the modulation of neurotransmission, neuroplasticity, and neural network activity as putative mechanisms of these rapid-acting antidepressants, highlighting differences on intracellular signaling pathways of synaptic proteins such as mammalian target of rapamycin (mTOR), extracellular signal-regulated kinase (ERK) and brain-derived neurotrophic factor (BDNF). In addition, we discuss probable mechanisms involved in the side effects of ketamine and its enantiomers.

Electroacupuncture Attenuated Anxiety and Depression-Like Behavior via Inhibition of Hippocampal Inflammatory Response and Metabolic Disorders in TNBS-Induced IBD Rats

This study was designed to explore the potential mechanisms of electroacupuncture (EA) in treating inflammatory bowel disease- (IBD-) related anxiety and mood disorders. A colitis model was induced in rats with 2, 4, 6-trinitrohydrosulfonic acid (TNBS), followed by ST36 and SP6 targeted therapy by EA or sham EA treatment. The elevated plus maze (EPM) and open-field test (OFT) were performed to assess the state of anxiety and depression-like behavior. Tests were carried out by 16S rDNA amplification sequence, ¹H nuclear magnetic resonance (¹H NMR) spectroscopy, immunofluorescence staining, and enzyme-linked immunosorbent assay (ELISA). The analyses detailed metabolic alterations and the Toll-like receptor 4 (TLR4) signaling pathway/NOD-like receptor protein 3 (NLRP3) inflammasome in rats' hippocampal region. Furthermore, the activity of the hypothalamic-pituitary adrenal (HPA) axis and gut microbiome was assessed. As a result of treatment, EA significantly improved in the behavioral tests and altered the composition of the gut microbiome through a significant increase in the density of short chain fatty acids (SCFAs) producers mainly including Ruminococcaceae, Phascolarctobacterium, and Akkermansiaceae. EA upregulated the metabolites of the hippocampus mainly containing l-glutamine and gamma-aminobutyric acid (GABA), as well as ZO-1 expression. Whereas the treatment blocked the TLR4/nuclear factor- kappa B (NF-κB) signaling pathways and NLRP3 inflammasomes, along with downregulating the interleukin- (IL-) 1β level. The hyperactivity of the HPA axis was also diminished. In conclusion, EA at ST36 and SP6 attenuated anxiety and depression-like behavior in colitis model rats through their effects on the gut microbiome by modulating the hippocampal inflammatory response and metabolic disorders, as well as the HPA axis. This study provides evidence for clinical application of EA to serve as an adjunctive treatment for IBD-related anxiety and depression.

Ketamine abrogates sensorimotor deficits and cytokine dysregulation in a chronic unpredictable mild stress model of depression

Major depressive disorder (MDD) is a serious mental disorder with influence across the functional systems of the body. The pathogenesis of MDD has been known to involve the alteration of normal body functions responsible for the normal inflammation processes within the CNS; this along with other effects results in the depreciation of the sensorimotor performance of the body. Ketamine hydrochloride, a novel antidepressant agent, has been used as a therapeutic agent to treat MDD with its efficacy stretching as far as enhancing sensorimotor performance and restoring normal cytokine levels of the CNS. While these therapeutic actions of ketamine may or may not be related, this study made use of chronic unpredictable mild stress (CUMS) to generate the mouse model of depression. The efficacy of ketamine as an antidepressant following sequential exposure and co-administrative treatment protocols of administration was evaluated using behavioural tests for sensorimotor performance and depressive-like behaviours. Its effect in managing CNS inflammation was assessed via the biochemical analysis of inflammatory cytokine levels in the cerebrum, spinal cord and cerebellum; and immunohistochemical demonstration of microglial activity in the corpus striatum and cerebellum. The sensorimotor performance which had been diminished by CUMS showed greater improvement under the sequential exposure regimen of ketamine. Ketamine was also efficacious in decreasing the level of inflammation with an evident reduction in microglial activation and pro-inflammatory cytokines in the studied regions, following CUMS exposure. Taken together, our study indicates that ketamine therapy can improve sensorimotor deficits co-morbid with a depressive disorder in parallel with modulation of the inflammatory system.

Potential Mechanisms and Clinical Effectiveness of Acupuncture in Depression

Major depressive disorder is the most common mental disorder with significant economic burden and limited treatments. Acupuncture has emerged as a promising non-pharmacological treatment for reducing depressive symptoms. However, the potential mechanisms and clinical effectiveness of acupuncture are not fully understood. This review aimed to: (1) summarize the available evidence on the mechanisms and clinical effectiveness of acupuncture for depression, and then (2) compare with pharmacological interventions, guiding future studies. Studies with animal models of depression and patients have shown that acupuncture could increase hippocampal and network neuroplasticity and decrease brain inflammation, potentially to alleviating depressive disorders. Overall clinical studies indicated that acupuncture could relieve primary depression, particularly milder cases, and was helpful in the management of post-stroke depression, pain-related depression, and postpartum depression both as an isolated and adjunct treatment. It was emphasized that acupuncture combined with antidepressant pharmacological treatment not only enhanced the improvement of primary and secondary depressive symptoms but also reduced the side effects of the medical treatment, which is the main cause for high dropout rates with drug treatment. In summary, substantial evidence from animal and human researches supported the beneficial effect of acupuncture in depression. However, most clinical trials of acupuncture were small, and it is unclear whether their findings can be generalized, so more studies are needed.

Translational evidence for the Inflammatory Response System (IRS)/Compensatory Immune Response System (CIRS) and neuroprogression theory of major depression

Major depressive disorder (MDD) is a common, severe and disabling neuropsychiatric disorder with a heterogenous etiology. Among the most widely recognized etiological models, immunopathogenesis is a predominant one. Numerous studies have demonstrated aberrant levels of inflammatory markers in the peripheral blood, cerebrospinal fluid (CSF) and brain of patients with MDD. Multiple studies including meta-analyses have reported increased peripheral levels of acute phase proteins, and pro-inflammatory cytokines, particularly IL-1β, TNF-α, and IL-6 in MDD. Postmortem brain studies similarly demonstrated upregulated expressions of these pro-inflammatory cytokines. This along with evidence of monocytic, lymphocytic and microglial activation, suggest an activated inflammatory response system (IRS) in MDD. A few studies show increased levels of anti-inflammatory cytokines or defective inflammatory pathways and a deficit in T cell maturation and responses in MDD patients. This suggests the presence of a Compensatory Immune Response System (CIRS), which can counterbalance the effects of IRS in major depression. More recently, simultaneously increased levels of both the pro-and anti-inflammatory cytokines are reported in the brain of MDD patients; this indicates activity of both the IRS and CIRS in MDD. The IRS and CIRS are the evolutionarily conserved and integral elements of an overarching system. The relevance of a dysregulated IRS-CIRS system in the neurobiological construct of MDD is just beginning to be understood. Speculation is rife that the disrupted IRS-CIRS elements might determine the onset, episodes, neuroprogressive processes, treatment response as well as recovery of patients with MDD. Notably, the signatures of an activated IRS-CIRS might emerge as potential biomarkers of MDD. Herein, an attempt has been made to highlight the biology and pathobiological relevance of IRS-CIRS activation in MDD and provide an insight into the role of these components in pharmacological therapy.

Does cognitive behaviour therapy affect peripheral inflammation of depression? A protocol for the systematic review and meta-analysis

INTRODUCTION

Cognitive-behavioural therapy (CBT) is becoming the most commonly implemented and standard treatment for depression. Up to date, only a few numbers of studies have investigated the potential relationship between CBT and the change of inflammatory biomarkers in individuals of depression. And the results are inconsistent among studies. The current study aims to provide a comprehensive, systematic review of the association between CBT and changes of peripheral inflammation of individuals with depression, and clarify the alterations of inflammatory cytokines pre-CBT and post-CBT treatment by meta-analysis, anti-inflammatory.

METHODS AND ANALYSIS

This study will be conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A systematic search of predetermined terms will be conducted with electronic databases of CENTRAL, MEDLINE, EMBASE and PsycINFO from inception to July 2021. Database searches will be supplemented by expert contact, reference and citation checking, and grey literature. Primary outcomes of interest will be validated measures for levels of inflammatory cytokines pre-CBT and post- CBT treatment in individuals with depression. Hedges' g will be used to represent the effect size.

SYSTEMATIC REVIEW REGISTRATION

The protocol of current meta-analysis has been registered at the Open Science Framework (https://doi.org/10.17605/osf.io/tr9yh).

ETHICS AND DISSEMINATION

Formal ethical approval is not required by the National Ethical Review Board in China as primary data will not be collected. The results alterations of peripheral inflammatory cytokines pre-CBT and post-CBT treatment in individuals with depression will be disseminated through a peer-reviewed publication and inform the most up-to-date evidence of the roles of CBT treatment for depression.

The Pattern of Change in Depressive Symptoms and Inflammatory Markers After Electroconvulsive Therapy: A Systematic Review

ABSTRACT

Depression is a major mental health disorder, and its pathophysiology is still largely unknown, as is the action mechanism of electroconvulsive therapy (ECT). Some evidence suggests that inflammation might play a role in depression, and several studies have attempted to demonstrate a link between ECT and cytokines. This systematic review used a qualitative analysis to assess the effect of ECT on inflammatory markers as it relates to the clinical response of depressive symptoms in major depressive disorders. The bibliographic search engines CINAHL, Embase, PsychInfo, and PubMed were used to identify articles published up to July 2020. Search terms related to depression, ECT, and inflammation were used. Descriptive statistical analyses were performed to relate changes in inflammatory markers to clinical response to ECT. Twenty-five studies were included in the analysis. No systematic increases or decreases were found in a given inflammatory marker over the ECT; however, we observed that tumor necrosis factor α and interleukin-6 (IL-6) were more often found to be decreased after ECT, whereas IL-8 and IL-10 were more often found to be increased after treatment. No trend in correlation was found between the degree of clinical improvement of depressive symptoms and the variation of any inflammatory markers, despite positive clinical response to ECT. Great heterogeneity with regard to methodology used and lack of power of the studies included in this review could explain the lack of systematic change and correlation found in this study. Future research conducted on this subject should take into account these methodological limitations to allow subsequent meta-analysis.

The current understanding of the benefits, safety, and regulation of cannabidiol in consumer products

The popularity of cannabidiol (CBD) in consumer products is soaring as consumers are using CBD for general health and well-being as well as to seek relief from ailments especially pain, inflammation, anxiety, depression, and sleep disorders. However, there are limited data currently in the public domain that provide support for these benefits. By contrast, a significant amount of safety evaluation data for CBD have been obtained recently from pre-clinical and clinical studies of the CBD therapeutic Epidiolex®. Yet some key data gaps concerning the safe use of CBD still remain. Furthermore, current regulations on CBD use in consumer products remain uncertain and often conflict between the state and federal level. In light of the rapidly expanding popularity of CBD-related products in the marketplace, here we review the current understanding of the benefits, safety, and regulations surrounding CBD in consumer products. This review does not advocate for or against the use of CBD in consumer products. Rather this review seeks to assess the state-of-the-science on the health effects and safety of CBD, to identify critical knowledge gaps for future studies, and to raise the awareness of the current regulations that govern CBD use in consumer products.

Isoginkgetin treatment attenuated lipopolysaccharide-induced monoamine neurotransmitter deficiency and depression-like behaviors through downregulating p38/NF-κB signaling pathway and suppressing microglia-induced apoptosis

BACKGROUND

Microglia activation-induced neuroinflammation may contribute to the etiology of depression. Podocarpus nagi containing high concentration of isoginkgetin could effectively treat mental diseases in ancient times. However, the therapeutic role, peculiarly in the brain-immune modulation in depression is still unclear. This study aimed to determine effects of isoginkgetin on lipopolysaccharide (LPS)-induced depression-like changes. Furthermore, its modulation on the p38/nuclear factor-kappa B (NF-κB) pathway in LPS-activated microglia was evaluated.

METHODS

Adult Kunming mice were intraperitoneally injected vehicle or isoginkgetin (4 mg/kg) daily for 14 days before saline or LPS (0.83 mg/kg) administration. Depression-like behavior, neurotransmitter levels, and markers of neuroinflammation were determined. Isoginkgetin effect on LPS-induced microglial activation was then assessed in BV2 cells. Finally, conditioned medium (CM) derived from isoginkgetin-treated BV2 cells was co-cultured with SH-SY5Y cells for 24 h. Cell viability and apoptosis were evaluated.

RESULTS

LPS significantly induced helplessness and anxiety, which were associated with decreased 5-HT, noradrenaline, and dopamine concentrations. Meanwhile, LPS increased microglia M1 hallmark Iba1 expression and serum interleukin (IL)-1β concentration. These changes were attenuated by isoginkgetin treatment. In vitro, isoginkgetin markedly suppressed the production of IL-1β, IL-6, tumor necrosis factor-alpha, cyclooxygenase-2, inducible nitric oxide, and reactive oxygen species, which are released from LPS-stimulated BV2 cells. More interestingly, CM from isoginkgetin-treated BV2 cells significantly alleviated SH-SY5Y cell apoptosis and restored cell viability compared to LPS-treated group through the inhibition of p38/NF-κB signaling pathway.

CONCLUSION

These data demonstrate that isoginkgetin is an effective therapeutic agent for depression-like behaviors and neuropathological changes via potent anti-inflammatory property.

Stress Diminishes BDNF-stimulated TrkB Signaling, TrkB-NMDA Receptor Linkage and Neuronal Activity in the Rat Brain

Exposure to intense or repeated stressors can lead to depression or post-traumatic stress disorder (PTSD). Neurological changes induced by stress include impaired neurotrophin signaling, which is known to influence synaptic integrity and plasticity. The present study used an ex vivo approach to examine the impact of acute or repeated stress on BDNF-stimulated TrkB signaling in hippocampus (HIPPO) and prefrontal cortex (PFC). Rats in an acute multiple stressor group experienced five stressors in one day whereas rats in a repeated unpredictable stressor group experienced 20 stressors across 10 days. After stress exposure, slices were incubated with vehicle or BDNF, followed by immunoprecipitation and immunoblot assays to assess protein levels, activation states and protein-protein linkage associated with BDNF-TrkB signaling. Three key findings are (1) exposure to stressors significantly diminished BDNF-stimulated TrkB signaling in HIPPO and PFC such that reductions in TrkB activation, diminished recruitment of adaptor proteins to TrkB, reduced activation of downstream signaling molecules, disruption of TrkB-NMDAr linkage, and changes in basal and BDNF-stimulated Arc expression were observed. (2) After stress, BDNF stimulation enhanced TrkB-NMDAr linkage in PFC, suggestive of compensatory mechanisms in this region. (3) We discovered an uncoupling between TrkB signaling, TrkB-NMDAr linkage and Arc expression in PFC and HIPPO. In addition, a robust surge in pro-inflammatory cytokines was observed in both regions after repeated exposure to stressors. Collectively, these data provide therapeutic targets for future studies that investigate how to reverse stress-induced downregulation of BDNF-TrkB signaling and underscore the need for functional studies that examine stress-related TrkB-NMDAr activities in PFC.

FBXO10 prevents chronic unpredictable stress-induced behavioral despair and cognitive impairment through promoting RAGE degradation

Aims

Depression is one of the leading causes of disability worldwide. The receptor for advanced glycosylation end products (RAGE) is closely related to chronic stress and is a target of F‐box protein O10 (FBXO10) which promotes the degradation of RAGE by ubiquitination. Here, we explored the role of FBXO10 and RAGE in chronic unpredictable stress (CUS)‐induced behavioral despair, cognitive impairment, neuroinflammation, and the polarization microglia.

Methods

Male C57BL/6 mice with or without infusion of viral in the medial prefrontal cortex (PFC) were subjected to CUS. Then the mice were exposed to forced swim test, sucrose consumption test, novelty‐suppressed feeding test, and temporal object recognition task to assess the behavioral despair and cognitive impairment. Inflammatory cytokines and the neurotrophic factor brain‐derived neurotrophic factor (BDNF) levels in PFC were assessed by enzyme‐linked immunosorbent assay. Immunofluorescence and immunohistochemistry staining were performed to observe the activation and phenotypic transformation of microglia in PFC. LPS‐induced cell model was constructed to explore the effect of FBXO10/RAGE axis in the polarization of microglia in vitro.

Results

FBXO10 promoted RAGE degradation by ubiquitination in BV2 cells. FBXO10 protein levels were reduced whereas RAGE protein levels were enhanced in CUS mice. FBXO10 overexpression or RAGE knockdown inhibited proinflammatory cytokine release, promoted BDNF expression, mitigated the depressive‐like and cognitive impairment behaviors, and affected the polarization of microglia induced by CUS exposure. FBXO10/RAGE axis promoted the polarization of microglia from the M1 to the M2 phenotype in vitro. Moreover, p38 MAPK and NF‐κΒ were identified to be the downstream effect factors for FBXO10/RAGE axis.

Conclusions

FBXO10 administration prevents CUS‐induced behavioral despair, cognitive impairment, neuroinflammation, and the polarization of microglia through decreasing the accumulation of RAGE, p38 MAPK, and NF‐κΒ, suggesting potential therapeutic strategies for the prevention and treatment of depression.

Effect of diet enriched with Agaricus bisporus polysaccharides (ABPs) on antioxidant property, innate-adaptive immune response and pro-anti inflammatory genes expression in Ctenopharyngodon idella against Aeromonas hydrophila

The effect of Agaricus bisporus polysaccharides (ABPs) supplemented diet on growth rate, antioxidant capacity, innate-adaptive immune response, proinflammatory and antiinflammatory genes expression in Ctenopharyngodon idella against Aeromonas hydrophila is reported. In both normal and challenged groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets resulted in a significant weight gain and feed intake. The survival was 100% in normal fish fed without or with any ABPs diet; the challenged fish fed with 1.0 mg kg^-1 ABPs diet had 98.6% survival. The RBC and WBC counts, Hb, and Hct levels were significant in both normal and challenged groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets. A significant increase in total protein and albumin level was observed in both groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets. Significant increase in GPx, ROS, GR, GSH, PC, and MnSOD activity was observed in HK of both groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets; similarly both groups when fed with the same ABPs diets showed significant Lz, C3, and C4 activity. However, both groups fed with 1.0 mg kg^-1 ABPs diet showed significant β-defensin, LEAP-2A, IL-6, and NF-κB P65 mRNA expression. Similarly, IFN-γ2, IL-10, and TNFα mRNA expressions were significant in both groups fed with 1.0 mg kg^-1 ABPs diet. The results indicate that both normal and challenged C. idella fed with a 1.0 mg kg^-1 ABPs diet had better growth, antioxidant status, immune response, and pro-anti-inflammatory gene modulation against A. hydrophila.

Antidepressant-like effects of helicid on a chronic unpredictable mild stress-induced depression rat model: Inhibiting the IKK/IκBα/NF-κB pathway through NCALD to reduce inflammation

We previously reported that helicid, an active plant monomer of Helicid nilgirica Bedd, had good antidepressant pharmacological activities. However, the potential mechanism of action remains unknown. Current investigation showed the antidepressant-like effects of helicid and its effects on the neurocalcin delta (NCALD) gene, and its mechanism of action through a depression model in rats exposed to chronic unpredictable mild stress (CUMS). We evaluated depression symptoms using the sucrose preference test (SPT), open field test (OFT), and forced swimming test (FST). By silencing NCALD and using rescue experiments, the IL-6, iNOS, IL-1β, COX-2, and TNF-α levels in the hippocampus or peripheral blood were determined using western blotting and ELISAs. The expression of IKKβ, p-IкBα, p-IKKβ, NF-кB p65, and IкBα were tested using western blots of the cytoplasmic or nuclear samples. Helicid and silencing NCALD relieved the CUMS-irritated depressive-like actions of rats, which were shown by increased consumption of sucrose, numbers of rearings, total running distance, zone crossings, and reduced immobility times. Helicid or silencing NCALD reversed the CUMS-induced high levels of IL-1β, COX-2, IL-6, TNF-α, and iNOS in the hippocampus or peripheral blood. Helicid or silencing NCALD also reduced the expressions of p-IκBα and p-IKKβ in the cytoplasm and the expression of nuclear NF-κB p 65 in hippocampus, and simultaneously elevated cytoplasmic expressions of IκBα, IKKβ, and NF-κB p65 in the hippocampus. Notably, after NCALD overexpression, the biochemical indices of rat helicid administration were reversed. In conclusion, the antidepressant action of helicid was mediated through NCALD in rats of CUMS by repressing hippocampal neuro-inflammation and abating the activation of the IKK/IκBα/NF-κB pathway.

Therapeutic Potential of Vagus Nerve Stimulation for Inflammatory Bowel Diseases

The vagus nerve is a mixed nerve, comprising 80% afferent fibers and 20% efferent fibers. It allows a bidirectional communication between the central nervous system and the digestive tract. It has a dual anti-inflammatory properties via activation of the hypothalamic pituitary adrenal axis, by its afferents, but also through a vago-vagal inflammatory reflex involving an afferent (vagal) and an efferent (vagal) arm, called the cholinergic anti-inflammatory pathway. Indeed, the release of acetylcholine at the end of its efferent fibers is able to inhibit the release of tumor necrosis factor (TNF) alpha by macrophages via an interneuron of the enteric nervous system synapsing between the efferent vagal endings and the macrophages and releasing acetylcholine. The vagus nerve also synapses with the splenic sympathetic nerve to inhibit the release of TNF-alpha by splenic macrophages. It can also activate the spinal sympathetic system after central integration of its afferents. This anti-TNF-alpha effect of the vagus nerve can be used in the treatment of chronic inflammatory bowel diseases, represented by Crohn’s disease and ulcerative colitis where this cytokine plays a key role. Bioelectronic medicine, via vagus nerve stimulation, may have an interest in this non-drug therapeutic approach as an alternative to conventional anti-TNF-alpha drugs, which are not devoid of side effects feared by patients.

Fluoxetine regulates eEF2 activity (phosphorylation) via HDAC1 inhibitory mechanism in an LPS-induced mouse model of depression

BACKGROUND

Selective serotonin reuptaker inhibitors, including fluoxetine, are widely studied and prescribed antidepressants, while their exact molecular and cellular mechanism are yet to be defined. We investigated the involvement of HDAC1 and eEF2 in the antidepressant mechanisms of fluoxetine using a lipopolysaccharide (LPS)-induced depression-like behavior model.

METHODS

For in vivo analysis, mice were treated with LPS (2 mg/kg BW), fluoxetine (20 mg/kg BW), HDAC1 activator (Exifone: 54 mg/kg BW) and NH125 (1 mg/kg BW). Depressive-like behaviors were confirmed via behavior tests including OFT, FST, SPT, and TST. Cytokines were measured by ELISA while Iba-1 and GFAP expression were determined by immunofluorescence. Further, the desired gene expression was measured by immunoblotting. For in vitro analysis, BV2 cell lines were cultured; treated with LPS, exifone, and fluoxetine; collected; and analyzed.

RESULTS

Mice treated with LPS displayed depression-like behaviors, pronounced neuroinflammation, increased HDAC1 expression, and reduced eEF2 activity, as accompanied by altered synaptogenic factors including BDNF, SNAP25, and PSD95. Fluoxetine treatment exhibited antidepressant effects and ameliorated the molecular changes induced by LPS. Exifone, a selective HDAC1 activator, reversed the antidepressant and anti-inflammatory effects of fluoxetine both in vivo and in vitro, supporting a causing role of HDAC1 in neuroinflammation allied depression. Further molecular mechanisms underlying HDAC1 were explored with NH125, an eEF2K inhibitor, whose treatment reduced immobility time, altered pro-inflammatory cytokines, and NLRP3 expression. Moreover, NH125 treatment enhanced eEF2 and GSK3β activities, BDNF, SNAP25, and PSD95 expression, but had no effects on HDAC1.

CONCLUSIONS

Our results showed that the antidepressant effects of fluoxetine may involve HDAC1-eEF2 related neuroinflammation and synaptogenesis.

Ibrutinib alleviates LPS-induced neuroinflammation and synaptic defects in a mouse model of depression

Previous studies have demonstrated a close association between an altered immune system and major depressive disorders, and inhibition of neuroinflammation may represent an alternative mechanism to treat depression. Recently, the anti-inflammatory activity of ibrutinib has been reported. However, the effect of ibrutinib on neuroinflammation-induced depression and its underlying mechanism has not been comprehensively studied. Therefore, we aimed to elucidate the potential anti-depressive role and mechanism of ibrutinib against neuroinflammation-induced depression and synaptic defects. Our results showed that ibrutinib treatment significantly reduced lipopolysaccharide (LPS)-induced depressive-like behaviors and neuroinflammation via inhibiting NF-kB activation, decreasing proinflammatory cytokine levels, and normalizing redox signaling and its downstream components, including Nrf2, HO-1, and SOD2, as well as glial cell activation markers, such as Iba-1 and GFAP. Further, ibrutinib treatment inhibited LPS-activated inflammasome activation by targeting NLRP3/P38/Caspase-1 signaling. Interestingly, LPS reduced the number of dendritic spines and expression of BDNF, and synaptic-related markers, including PSD95, snap25, and synaptophysin, were improved by ibrutinib treatment in the hippocampal area of the mouse brain. In conclusion, our findings suggest that ibrutinib can alleviate neuroinflammation and synaptic defects, suggesting it has antidepressant potential against LPS-induced neuroinflammation and depression.