Low-Dose Copper Exposure Exacerbates Depression-Like Behavior in ApoE4 Transgenic Mice

GABAB modulate NF-κB/NLRP3 pathways in electroacupuncture prevention of depression in CUMS rats

BACKGROUND

Our previous research has demonstrated that electroacupuncture (EA) has the potential to mitigate depression-like symptoms resulting from chronic stress. However, further investigation is required to fully understand the underlying mechanisms. The regulatory role of γ-aminobutyric acid type B (GABAB) in synaptic plasticity and the involvement of NF-κB/NLRP3-mediated inflammation in the lateral habenula nucleus (LHb) are key factors in the development of depression. This study sought to investigate the potential of EA in mitigating depression-like symptoms induced by chronic stress through mechanisms such as enhancing GABAB levels, regulating synaptic plasticity in the LHb, and suppressing NF-κB/NLRP3-mediated inflammation.

METHODS

Sprague-Dawley rats were exposed to chronic unpredictable mild stress (CUMS) in order to create a model of depression. Subsequently, the weight and behavioral assessments of all rats were monitored, and samples of the lateral habenula and serum were collected. The protein expression levels were analyzed using western blotting. The 5-hydroxytryptophan (5-HT), Dopamine (DA), and Norepinephrine (NE) in the LHb and serum were measured using ELISA. The alterations in GABAB and NF-κB in the LHb were observed through immunofluorescence. The neuronal damage in the LHb was assessed using Nissl staining.

RESULTS

EA upregulated the expression of GABAB in the LHb of rats subjected to CUMS. Subsequent behavioral assessments indicated that blocking GABAB attenuated the antidepressant effects of EA in CUMS-exposed rats. Furthermore, EA enhanced synaptic plasticity in the LHb of CUMS-exposed rats and mitigated NF-κB/NLRP3-mediated inflammatory responses, with these effects potentially being reversed by GABAB inhibition.

CONCLUSION

Through the promotion of GABAB levels, regulation of synaptic plasticity within the LHb, and inhibition of NF-κB/NLRP3-mediated neuroinflammation in the same region, electroacupuncture at Shangxing and Fengfu acupoints demonstrates efficacy in mitigating depression-like behaviors induced by CUMS.

Mechanism of Cu entry into the brain: many unanswered questions

Brain tissue requires high amounts of copper (Cu) for its key physiological processes, such as energy production, neurotransmitter synthesis, maturation of neuropeptides, myelination, synaptic plasticity, and radical scavenging. The requirements for Cu in the brain vary depending on specific brain regions, cell types, organism age, and nutritional status. Cu imbalances cause or contribute to several life-threatening neurologic disorders including Menkes disease, Wilson disease, Alzheimer's disease, Parkinson's disease, and others. Despite the well-established role of Cu homeostasis in brain development and function, the mechanisms that govern Cu delivery to the brain are not well defined. This review summarizes available information on Cu transfer through the brain barriers and discusses issues that require further research.

Obesity Mediates the Association Between Serum Copper and Inflammation: A Cross-sectional and Mendelian Randomization Study

Copper is an important biological trace element, but its overexposure can be harmful to the human body. Herein, we aimed to assess the association between serum copper levels and inflammation. A total of 5231 participants were analyzed from the National Health and Nutrition Examination Survey (NHANES) between 2011 and 2016. Participants with higher serum copper levels had higher values of systemic inflammation indexes. The concentration of high-sensitive C-reactive protein (hs-CRP) increased with serum copper concentration (β = 2.8, p < 0.001). Participants with high and very high copper levels had higher ORs (odds ratios) of having inflammation (high: OR 2.92 (0.77-11.04), p = 0.074; very high: OR 8.66 (3.18-23.54), p = 0.011), which were further exacerbated in people with diabetes and males. Body mass index (BMI) and body fat percentage are two main mediators in the association between serum copper and hs-CRP, accounting for 12.62% and 19.72%, respectively. The random-effects inverse variance-weighted (IVW) analysis revealed that there was a genetic causal relationship between serum copper and obesity (OR 1.15, p = 0.014). Our results suggest that serum copper is positively associated with inflammation, which may be mainly mediated by obesity.

Association between dietary copper intake and constipation in US adults

Dietary micronutrients are integral to the development and progression of constipation; however, the specific relationship between dietary copper intake and constipation has not been thoroughly investigated. This study aims to examine the correlation between dietary copper intake and constipation among U.S. adults, thereby offering novel insights and recommendations for the clinical management and prevention of constipation. Bowel health data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2005 and 2010 were analyzed. Subjects' dietary information was collected through questionnaire records. Multivariate logistic regression analysis, subgroup analysis, and curve fitting analysis were used to assess the correlation between dietary copper intake and chronic constipation. After adjusting for all possible confounders, each unit increase in dietary copper intake (converted to natural logarithms) was associated with a 20% reduction in the prevalence of constipation (OR = 0.80; 95% CI 0.65-0.98; P = 0.037). The interaction P-values for all subgroups were greater than 0.05, indicating that the findings were stable and consistent across subgroups. The present study showed a significant negative association between dietary copper intake and chronic constipation in adults. This finding raises clinical and healthcare professionals' awareness of the impact of dietary trace elements on intestinal health and has important implications for the development of personalized meal plans and rational supplementation of trace copper in patients with constipation.

Celiac disease and depressive disorders as nutritional implications related to common factors - A comprehensive review

Celiac disease (CD) is an immune-mediated disease affecting the small intestine. The only treatment strategy for CD is the gluten-free diet (GFD). One of the more common mental disorders in CD patients is major depressive disorder (MDD). The influence of GFD on the occurrence of MDD symptoms in patients with CD will be evaluated. This diet often reduces nutritional deficiencies in these patients and also helps to reduce depressive symptoms. Both disease entities are often dominated by the same deficiencies of nutrients such as iron, zinc, selenium, iodine, or B and D vitamins. Deficiencies of particular components in CD can favor MDD and vice versa. Gluten can adversely affect the mental state of patients without CD. Also, intestinal microbiota may play an important role in the described process. This work aims to comprehensively assess the common factors involved in the pathomechanisms of MDD and CD, with particular emphasis on nutrient imbalances. Given the complexity of both disease entities, and the many common links, more research related to improving mental health in these patients and the implementation of a GFD would need to be conducted, but it appears to be a viable pathway to improving the quality of life and health of people struggling with CD and MDD. Therefore, probiotics, micronutrients, macronutrients, and vitamin supplements are recommended to reduce the risk of MDD, given that they may alleviate the symptoms of both these disease entities. In turn, in patients with MDD, it is worth considering testing for CD.

Serotonin 2A Receptor (5-HT2AR) Agonists: Psychedelics and Non-Hallucinogenic Analogues as Emerging Antidepressants

Psychedelics make up a group of psychoactive compounds that induce hallucinogenic effects by activating the serotonin 2A receptor (5-HT2AR). Clinical trials have demonstrated the traditional psychedelic substances like psilocybin as a class of rapid-acting and long-lasting antidepressants. However, there is a pressing need for rationally designed 5-HT2AR agonists that possess optimal pharmacological profiles in order to fully reveal the therapeutic potential of these agonists and identify safer drug candidates devoid of hallucinogenic effects. This Perspective provides an overview of the structure-activity relationships of existing 5-HT2AR agonists based on their chemical classifications and discusses recent advancements in understanding their molecular pharmacology at a structural level. The encouraging clinical outcomes of psychedelics in depression treatment have sparked drug discovery endeavors aimed at developing novel 5-HT2AR agonists with improved subtype selectivity and signaling bias properties, which could serve as safer and potentially nonhallucinogenic antidepressants. These efforts can be significantly expedited through the utilization of structure-based methods and functional selectivity-directed screening.

Insight into the effect of a heavy metal mixture on neurological damage in rats through combined serum metabolomic and brain proteomic analyses

The heavy metals lead (Pb), cadmium (Cd), and mercury (Hg) that cause neurocognitive impairment have been extensively studied. These elements typically do not exist alone in the environment; they are often found with other heavy metals and can enter the body through various routes, thereby impacting health. Our previous research showed that low Pb, Cd, and Hg levels cause neurobehavioral impairments in weaning and adult rats. However, little is known about the biomarkers and mechanisms underlying Pb, Cd, and Hg mixture-induced neurological impairments. A combined analysis of metabolomic and proteomic data may reveal heavy metal-induced alterations in metabolic and protein profiles, thereby improving our understanding of the molecular mechanisms underlying heavy metal-induced neurological impairments. Therefore, brain tissue and serum samples were collected from rats exposed to a Pb, Cd, and Hg mixture for proteomic and metabolomic analyses, respectively. The analysis revealed 363 differential proteins in the brain and 206 metabolites in serum uniquely altered in the Pb, Cd, and Hg mixture exposure group, compared to those of the control group. The main metabolic impacted pathways were unsaturated fatty acids biosynthesis, linoleic acid metabolism, phenylalanine metabolism, and tryptophan metabolism. We further identified that the levels of arachidonic acid (C20:4 n-3) and, adrenic acid (C22:4 n-3) were elevated and that kynurenic acid (KA) and quinolinic acid (QA) levels and the KA/QA ratio, were decreased in the group exposed to the Pb, Cd, and Hg mixture. A joint analysis of the proteome and metabolome showed that significantly altered proteins such as LPCAT3, SLC7A11, ASCL4, and KYAT1 may participate in the neurological impairments induced by the heavy metal mixture. Overall, we hypothesize that the dysregulation of ferroptosis and kynurenine pathways is associated with neurological damage due to chronic exposure to a heavy metal mixture.

Low-dose Cu exposure enhanced α-synuclein accumulation associates with mitochondrial impairments in mice model of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder that mainly affects the elder population, and its etiology is enigmatic. Both environmental risks and genetics may influence the development of PD. Excess copper causes neurotoxicity and accelerates the progression of neurodegenerative diseases. However, the underlying mechanisms of copper-induced neurotoxicity remain controversial. In this study, A53T transgenic α-synuclein (A53T) mice and their matching wild-type (WT) mice were treated with a low dose of copper (0.13 ppm copper chlorinated drinking water, equivalent to the copper exposure of human daily copper intake dose) for 4 months, and copper poisoning was performed on human A53T mutant SHSY5Y cells overexpressed with α-synuclein (dose of 1/4 IC50), to test the effects of copper exposure on the body. The results of the open field test showed that the moto function of Cu-treated mice was impaired. Proteomics revealed changes in neurodevelopment, transport function, and mitochondrial membrane-related function in Cu-treated WT mice, which were associated with reduced expression of mitochondrial complex (NDUFA10, ATP5A), dopamine neurons (TH), and dopamine transporter (DAT). Mitochondrial function, nervous system development, synaptic function, and immune response were altered in Cu-treated A53T mice. These changes were associated with increased mitochondrial splitting protein (Drp1), decreased mitochondrial fusion protein (OPA1, Mfn1), abnormalities in mitochondrial autophagy protein (LC3BII/I, P62), decreased dopamine neuron (TH) expression, increased α-synuclein expression, inflammatory factors (IL-6, IL-1β, and TNF-α) release and microglia (Iba1) activation. In addition, we found that Cu2+ (30 μM) induced excessive ROS production and reduced mitochondrial ATP production in human A53T mutant α-synuclein overexpressing SHSY5Y cells by in vitro experiments. In conclusion, low-dose copper treatment altered critical proteins involved in mitochondrial, neurodevelopmental, and inflammatory responses and affected mitochondria's ROS and ATP production levels.

The emerging role of copper in depression

Copper (Cu) is an essential trace element in the brain and serves as an important cofactor for numerous enzymes involved in a wide range of biochemical processes including neurobehavioral, mitochondrial respiration, and antioxidant effects. Recent studies have demonstrated that copper dyshomeostasis is tightly associated with the development of depression by inducing oxidative stress and inflammatory responses. However, these findings have remained controversial so far. Cumulative studies have shown a positive association, while some other studies showed no association and even a negative association between serum/plasma copper level and depression. Based on these conflicted results, the association was speculated to be due to the clinical features of the population, stages of the disease, severity of copper excess, and types of specimens detected in these studies. In addition, there was an inverse association between dietary copper intake and depression. Furthermore, increasing copper intake could influence dietary zinc and iron intake to prevent and treat depression. Thus, copper supplementation may be a good measure to manage depression. This review provided a deeper understanding of the potential applicability of copper in the prevention and treatment of depression.

Association between serum copper, zinc, and selenium concentrations and depressive symptoms in the US adult population, NHANES (2011-2016)

BACKGROUND

Evidence suggests that alterations in serum trace element concentrations are closely associated with mental illness. However, ​studies on the relationship between serum copper, zinc, and selenium concentrations and depressive symptoms are limited and with controversial results. We aimed to investigate the association between serum concentrations of these trace elements and depressive symptoms in US adults.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES) (2011-2016) were used in this cross-sectional study. The Patient Health Questionnaire-9 Items (PHQ-9) was employed to assess depressive symptoms. Multiple logistic regression was performed to determine the relationship between the serum concentrations of copper, zinc, and selenium and depressive symptoms.

RESULTS

A total of 4552 adults were included. Subjects with depressive symptoms had higher serum copper concentrations (123.88 ± 1.87) than those without depressive symptoms (116.99 ± 0.86) (p < 0.001). In Model 2, weighted logistic regression analysis showed that the second (Q2) quartile of zinc concentrations (odds ratio [OR] = 1.534, 95% confident interval [CI]: 1.018 to 2.313) were significantly associated with an increased risk of depressive symptoms. Subgroup analysis revealed that the third (Q3) and fourth (Q4) quartiles of copper concentrations (Q3: OR = 2.699, 95% CI: 1.285 to 5.667; Q4: OR = 2.490, 95% CI: 1.026 to 6.046) were also positively associated with depressive symptoms in obese individuals after controlling for all confounders. However, no significant relationship between serum selenium concentrations and depressive symptoms was observed.

CONCLUSIONS

Obese US adults with high serum copper concentrations, as well as US adults in general with low serum zinc concentrations, were susceptible to depressive symptoms. Nevertheless, the causal mechanisms underlying these relationships need to be further explored.

Appropriate Macronutrients or Mineral Elements Are Beneficial to Improve Depression and Reduce the Risk of Depression

Depression is a common mental disorder that seriously affects the quality of life and leads to an increasing global suicide rate. Macro, micro, and trace elements are the main components that maintain normal physiological functions of the brain. Depression is manifested in abnormal brain functions, which are considered to be tightly related to the imbalance of elements. Elements associated with depression include glucose, fatty acids, amino acids, and mineral elements such as lithium, zinc, magnesium, copper, iron, and selenium. To explore the relationship between these elements and depression, the main literature in the last decade was mainly searched and summarized on PubMed, Google Scholar, Scopus, Web of Science, and other electronic databases with the keywords "depression, sugar, fat, protein, lithium, zinc, magnesium, copper, iron, and selenium". These elements aggravate or alleviate depression by regulating a series of physiological processes, including the transmission of neural signals, inflammation, oxidative stress, neurogenesis, and synaptic plasticity, which thus affect the expression or activity of physiological components such as neurotransmitters, neurotrophic factors, receptors, cytokines, and ion-binding proteins in the body. For example, excessive fat intake can lead to depression, with possible mechanisms including inflammation, increased oxidative stress, reduced synaptic plasticity, and decreased expression of 5-Hydroxytryptamine (5-HT), Brain Derived Neurotrophic Factor (BDNF), Postsynaptic density protein 95(PSD-95), etc. Supplementing mineral elements, such as selenium, zinc, magnesium, or lithium as a psychotropic medication is mostly used as an auxiliary method to improve depression with other antidepressants. In general, appropriate nutritional elements are essential to treat depression and prevent the risk of depression.

The first trimester plasma copper-zinc ratio is independently related to pregnancy-specific psychological distress symptoms throughout pregnancy

OBJECTIVES

High plasma copper (Cu) and low zinc (Zn) levels have been associated with depression. However, most studies used low sample sizes and a cross-sectional design, and perinatal data are scarce. We investigated the possible association between pregnancy-specific psychological distress and the plasma CuZn ratio using a prospective design.

METHODS

Pregnancy-specific distress symptoms were assessed at each trimester by means of the Tilburg Pregnancy Distress Scale, negative affect subscale, in 2036 pregnant women. Cu and Zn were assessed at 12 wk of gestation in plasma samples by inductively coupled plasma mass spectrometry. Growth mixture modeling determined trajectories of women's pregnancy-specific negative affect (P-NA) symptoms, which were entered in a multiple logistic regression analysis as dependent variable and the CuZn ratio as independent variable.

RESULTS

Two P-NA symptom classes were found: 1) persistently low (n = 1820) and 2) persistently high (n = 216). A higher CuZn ratio was independently associated with persistently high P-NA symptom scores (odds ratio = 1.52; 95% confidence interval, 1.13-2.04) after adjustment for confounders. A sensitivity analysis was performed excluding all women with high P-NA scores at 12 wk (>1 SD above the mean P-NA score). In the 1719 remaining women, a higher CuZn ratio significantly predicted the development of increasing P-NA symptom scores after adjustment for confounders (odds ratio = 1.40; 95% confidence interval, 1.04-1.95).

CONCLUSIONS

A higher CuZn plasma ratio is an independent determinant of developing pregnancy-specific distress symptoms throughout pregnancy, suggesting that micronutrients could be used as novel biomarkers for psychological distress research of perinatal mood disorders.

BMI Modifies the Association Between Depression Symptoms and Serum Copper Levels

Depression is one of the most common mental disorders which dramatically threatens public health and wellness. Copper has been known to be involved in many biological processes that could help explaining the occurrence of depression. However, studies focusing on its effect have yielded mixed results. The present study aims to evaluate the association between serum copper levels and depression symptoms. It also investigates the effect of modification of BMI (body mass index) on depression symptoms. A total of 5419 US adults aged 20 years or older from the National Health and Nutrition Examination Survey (NHANES) 2011-2016 participated in the cross-sectional study. Logistic regression models were applied using depression levels as the outcome and serum cooper/selenium/zinc categories as the main predictor, with the adjustments of gender, age, marital status, race, education, family income level, alcohol drinking, cigarette smoking, diabetes, pressure, stroke, and BMI. The interaction terms for copper levels and other covariates were further incorporated into the model to assess their roles in predicting depression symptoms. The prevalence of depression symptoms was significantly higher in samples with a high copper level. Among the levels of serum copper, selenium, and zinc, only the association between depression symptoms and serum copper levels was observed to be significant in the unadjusted model (P = 0.002). Individuals with a high copper level (114-134 μg/dL) and a very high copper level (≥ 134 μg/dL) had 1.85 (95% CI 1.24, 2.77)- and 1.72 (95% CI 1.21, 2.44)-fold higher odds ratio of depression symptoms, respectively, compared to those with a normal serum copper level. Although the association was not significant in the adjusted models, in which confounders were added, the interaction of copper level, including high and very high copper levels, and obesity (BMI ≥ 30 kg/m²) exhibited significantly higher odds ratio (4.12 (95% CI 1.38, 12.27) and 4.53 (95% CI 1.87, 10.96)) of having depression symptoms. The concentration of serum copper was positively associated with the prevalence of depression symptoms. Obesity exacerbated the risk of having depression symptoms in people with high serum copper levels.

Research on the MEG of Depression Patients Based on Multivariate Transfer Entropy

The pathogenesis of depression is complex, and the current means of medical diagnosis is single. Patients with severe depression may even have great physical pain and suicidal tendencies. Magnetoencephalography (MEG) has the characteristics of ultrahigh spatiotemporal resolution and safety. It is a good medical means for the diagnosis of depression. In this paper, multivariate transfer entropy algorithm is used to study MEG of depression. In this paper, the subjects are divided into the same brain region and the multichannel combination between different brain regions, and the multivariate transfer entropy of patients with depression and healthy controls under different EEG signal frequency bands is calculated. Finally, the significant difference between the two groups of experimental samples is verified by the results of independent sample t-test. The experimental results show that for the same combination of brain channels, the multivariate transfer entropy in the depression group is generally lower than that in the healthy control group, and the difference is the best in γ frequency band and the largest in the frontal region.

Is There a Connection between the Metabolism of Copper, Sulfur, and Molybdenum in Alzheimer’s Disease? New Insights on Disease Etiology

Alzheimer’s disease (AD) and other forms of dementia was ranked 3rd in both the Americas and Europe in 2019 in a World Health Organization (WHO) publication listing the leading causes of death and disability worldwide. Copper (Cu) imbalance has been reported in AD and increasing evidence suggests metal imbalance, including molybdenum (Mo), as a potential link with AD occurrence.We conducted an extensive literature review of the last 60 years of research on AD and its relationship with Cu, sulfur (S), and Mo at out of range levels.Weanalyzed the interactions among metallic elements’ metabolisms;Cu and Mo are biological antagonists, Mo is a sulfite oxidase and xanthine oxidase co-factor, and their low activities impair S metabolism and reduce uric acid, respectively. We found significant evidence in the literature of a new potential mechanism linking Cu imbalance to Mo and S abnormalities in AD etiology: under certain circumstances, the accumulation of Cu not bound to ceruloplasmin might affect the transport of Mo outside the blood vessels, causing a mild Mo deficiency that might lowerthe activity of Mo and S enzymes essential for neuronal activity. The current review provides an updated discussion of the plausible mechanisms combining Cu, S, and Mo alterations in AD.

Associations of Dietary Copper, Selenium, and Manganese Intake With Depression: A Meta-Analysis of Observational Studies

Objective

To comprehensively summarize the evidence on the associations of dietary copper, selenium, and manganese intake with depression based on a meta-analysis of observational studies.

Methods

The electronic database of PubMed, Web of Science, and Embase were searched up to January 7, 2022, for observational studies on the associations of dietary copper, selenium and manganese intake with depression (no restriction was set for the initiate time). The pooled relative risk (RR) of depression for the highest vs. lowest dietary copper, selenium, and manganese intake category were calculated.

Results

A total of 11 observational studies (61,430 participants) were identified as meeting the inclusion criteria. Specifically, five studies were related to the dietary copper intake. The overall multi-variable adjusted RR demonstrated that dietary copper intake was inversely associated with depression (RR = 0.63, 95% CI: 0.52–0.76; P < 0.001; I² = 2.4%). With regard to the dietary selenium intake, six studies were identified for meta-analysis. The overall multi-variable adjusted RR showed that dietary selenium intake was also negatively associated with depression (RR = 0.63, 95% CI: 0.54–0.74; P < 0.001; I² = 37.8%). In addition, four studies were specified for the dietary manganese intake, and the overall multi-variable adjusted RR indicated a negative relationship between dietary manganese intake and depression (RR = 0.71, 95% CI: 0.58–0.86; P < 0.001; I² = 0.0%).

Conclusions

Our results suggest a negative relationship between dietary copper, selenium and manganese intake and depression, respectively. However, due to the limited prospective evidence, our results are restricted to cross-sectional design that precludes causal relationships. More well-designed prospective cohort studies are still needed.

Mechanism of Depression through Brain Function Imaging of Depression Patients and Normal People

In recent years, functional magnetic resonance technology has discovered that abnormal connections in different brain regions of the brain may serve as the pathophysiological mechanism of mental illness. Exploring the mechanism of information flow and integration between different brain regions is of great significance for understanding the pathophysiological mechanism of mental illness. This article aims to analyze the mechanism of depression by comparing human brain images of normal people and patients with depression and conduct research. Fluoxetine, a selective 5-HT reuptake inhibitor (SSRI) widely used in clinical practice, can selectively inhibit 5-HT transporter and block the reuptake of 5-HT by the presynaptic membrane. The effect of 5-HT is prolonged and increased, thereby producing antidepressant effects. It has low affinity for adrenergic, histaminergic, and cholinergic receptors and has a weaker effect, resulting in fewer adverse reactions. This paper uses the comparative experiment method and the Welch method and uses the average shortest path length L to describe the average value of the shortest path length between two nodes in the network. Attention refers to the ability of a person's mental activity to point and to concentrate on something. Sustained attention means that attention is kept on a certain cognitive object or activity for a certain period of time, which is also called the stability of attention. The research on attention of depression patients generally focuses on continuous attention, and the results obtained show inconsistencies. Most studies have shown that the sustained attention of the depression group is significantly worse than that of the healthy control group. An overview of magnetic resonance imaging technology and an analysis of depression based on resting state were carried out. The key brain areas of the sample core network were scanned, and the ALFF results were analyzed. The data showed that the severity of depression in the depression group was negatively correlated with the ReHo value in the posterior left cerebellum (P=0.010). The sense of despair was negatively correlated with the ReHo value in the posterior right cerebellum (P=0.013). The diurnal variation was negatively correlated with the ReHo value of the left ring (P=0.014). It was positively correlated with the ReHo value of the left ventricle (P=0.048). This experiment has better completed the research on the mechanism of depression by analyzing the functional images of patients with depression and normal human brain.

RGFP966 is protective against lipopolysaccharide-induced depressive-like behaviors in mice by inhibiting neuroinflammation and microglial activation

Depression is a prevalent mental disorder. However, its pathophysiological mechanism has still remained elusive, and a limited number of effective treatments have been presented. Recent studies have shown that neuroinflammation and microglial activation are involved in the pathogenesis of depression. Histone deacetylase 3 (HDAC3) has neurotoxic effects on several neuropathological conditions. The inhibition of HDAC3 has been reported to induce anti-inflammatory and antioxidant effects. RGFP966 is a highly selective inhibitor of HDAC3. This study aimed to investigate the antidepressant effect of RGFP966 on lipopolysaccharide (LPS)-induced depressive-like behaviors in mice and to explore its possible mechanism. Adult male C57BL/6J mice were utilized in this study. The LPS and RGFP966 were injected intraperitoneally daily for 5 days. The behavior tests were performed to elucidate the depression-like behaviors. Western blot, ELISA and immunofluorescence staining were used to study the HDAC3/TLR4/NLRP3 pathway-related proteins. The results of behavioral tests showed that RGFP966 could improve the LPS-induced depressive-like behaviors in mice. The results of Western blotting showed that RGFP966 treatment downregulated the expression levels of toll-like receptor 4 (TLR4), nucleotide-binding oligomerization domain-like receptor pyrin domain-containing-3 (NLRP3), caspase-1, and interleukin-1β (IL-1β) (P < 0.05). Furthermore, the results of immunofluorescence staining showed that RGFP966 treatment inhibited microglial activation in the hippocampus of mice (P < 0.01). These findings suggested that RGFP966 could effectively ameliorate LPS-induced depressive-like behaviors in mice by inhibiting neuroinflammation and microglial activation. The anti-inflammatory mechanism of RGFP966 might be related to the inhibition of the HDAC3/TLR4/NLRP3 signaling pathway. Therefore, inhibition of HDAC3 using RGFP966 could serve as a potential treatment strategy for depression.