Hippocampal CA1 βCaMKII mediates neuroinflammatory responses via COX-2/PGE2 signaling pathways in depression

The m6A eraser FTO suppresses ferroptosis via mediating ACSL4 in LPS-induced macrophage inflammation

Acute lung injury (ALI) is a serious disorder characterized by the release of pro-inflammatory cytokines and cascade activation of macrophages. Ferroptosis, a form of iron-dependent cell death triggered by intracellular phospholipid peroxidation, has been implicated as an internal mechanism underlying ALI. In this study, we investigated the effects of m6A demethylase fat mass and obesity-associated protein (FTO) on the inhibition of macrophage ferroptosis in ALI. Using a mouse model of lipopolysaccharide (LPS)-induced ALI, we observed the induction of ferroptosis and its co-localization with the macrophage marker F4/80, suggesting that ferroptosis might be induced in macrophages. Ferroptosis was promoted during LPS-induced inflammation in macrophages in vitro, and the inflammation was counteracted by the ferroptosis inhibitor ferrostatin-1 (fer-1). Given that FTO showed lower expression levels in the lung tissue of mice with ALI and inflammatory macrophages, we further dissected the regulatory capacity of FTO in ferroptosis. The results demonstrated that FTO alleviated macrophage inflammation by inhibiting ferroptosis. Mechanistically, FTO decreased the stability of ACSL4 mRNA via YTHDF1, subsequently inhibiting ferroptosis and inflammation by interrupting polyunsaturated fatty acid consumption. Moreover, FTO downregulated the synthesis and secretion of prostaglandin E2, thereby reducing ferroptosis and inflammation. In vivo, the FTO inhibitor FB23-2 aggravated lung injury, the inflammatory response, and ferroptosis in mice with ALI; however, fer-1 therapy mitigated these effects. Overall, our findings revealed that FTO may function as an inhibitor of the inflammatory response driven by ferroptosis, emphasizing its potential as a target for ALI treatment.

Cyclooxygenase-2 inhibitors alleviated depressive and anxious-like behaviors in mice exposed to lipopolysaccharide: Involvement of oxidative stress and neuroinflammation

Depression and anxiety disorders have their pathophysiologies linked to inflammation and oxidative stress. In this context, celecoxib (CLX) and etoricoxib (ETR) inhibit cyclooxygenase 2 (COX-2), an enzyme expressed by cells involved in the inflammatory process and found in the brain. Studies have been using CLX as a possible drug in the treatment of depression, although its mechanisms at the central nervous system level are not fully elucidated. In this study, the effects of CLX and ETR on behavioral, oxidative, and inflammatory changes induced by systemic exposure to Escherichia coli lipopolysaccharide (LPS) were evaluated in adult male swiss mice. For ten days, the animals received intraperitoneal injections of LPS at 0.5 mg/kg. From the sixth to the tenth day, one hour after LPS exposure, they were treated orally with CLX (15 mg/kg), ETR (10 mg/kg), or fluoxetine (FLU) (20 mg/kg). Twenty-four hours after the last oral administration, the animals underwent evaluation of locomotor activity (open field test), predictive tests for depressive-like behavior (forced swim and tail suspension tests), and anxiolytic-like effect (elevated plus maze and hole board tests). Subsequently, the hippocampus, prefrontal cortex and striatum were dissected for the measurement of oxidative and nitrosative parameters (malondialdehyde, nitrite, and glutathione) and quantification of pro-inflammatory cytokines (IL-1β and IL-6). LPS induced depressive and anxious-like behavior, and treatment with CLX or ETR was able to reverse most of the behavioral changes. It was evidenced that nitrosative stress and the degree of lipid peroxidation induced by LPS were reduced in different brain areas after treatment with the drugs, as well as the endogenous defense system against free radicals was strengthened. CLX and ETR also significantly reduced LPS-induced cytokine levels. These data are expected to expand information on the role of inflammation in depression and anxiety and provide insights into possible mechanisms of COX-2 inhibitors in psychiatric disorders with a neurobiological basis in inflammation and oxidative stress.

Monomeric pilose antler peptide improves depression-like behavior in mice by inhibiting FGFR3 protein expression

ETHNOPHARMACOLOGICAL RELEVANCE

It has been found that pilose antler peptide has an antidepressant effect on depression. However, the exact molecular mechanism of its antidepressant effect is still unclear.

AIM OF THE STUDY

The study sought to determine the impact of monomeric pilose antler peptide (PAP; sequence LVLVEAELRE) on depression as well as investigate potential molecular mechanisms.

MATERIALS AND METHODS

Chronic unexpected mild stress (CUMS) was used to establish the model, and the effect of PAP on CUMS mice was detected by the behavioral test. The influence of PAP on neuronal cells and dendritic spine density was observed by immunofluorescence and Golgi staining. FGFR3 and the CaMKII-associated pathway were identified using quantitative real-time polymerase chain reaction, and Western blot analysis was utilized to measure their proteins and gene expression levels. Molecular docking and microscale thermophoresis were applied to detect the binding of PAP and FGFR3. Finally, the effect of FGFR3's overexpression on PAP treatment of depression was detected.

RESULTS

PAP alleviated the changes in depressive behavior induced by CUMS, promoted the growth of nerve cells, and the density of dendritic spines was increased to its original state. PAP therapy successfully downregulated the expression of FGFR3 and ERK1/2 while upregulating the expression of CREB, BDNF, and CaMKII.

CONCLUSION

Based on the current research, PAP has a therapeutic effect on depression brought on by CUMS by inhibiting FGFR3 expression and enhancing synaptic plasticity.

Mind shift I: Fructus Aurantii - Rhizoma Chuanxiong synergistically anchors stress-induced depression-like behaviours and gastrointestinal dysmotility cluster by regulating psycho-immune-neuroendocrine network

BACKGROUND

Researchers have not studied the integrity, orderly correlation, and dynamic openness of complex organisms and explored the laws of systems from a global perspective. In the context of reductionism, antidepressant development formerly focused on advanced technology and molecular details, clear targets and mechanisms, but the clinical results were often unsatisfactory.

PURPOSE

MDD represents an aggregate of different and highly diverse disease subtypes. The co-occurrence of stress-induced nonrandom multimorbidity is widespread, whereas only a fraction of the potential clusters are well known, such as the MDD-FGID cluster. Mapping these clusters, and determining which are nonrandom, is vital for discovering new mechanisms, developing treatments, and reconfiguring services to better meet patient needs.

STUDY DESIGN

Acute stress 15-minute forced swimming (AFS) or CUMS protocols can induce the nonrandom MDD-FGID cluster. Multiple biological processes of rats with depression-like behaviours and gastrointestinal dysmobility will be captured under conditions of stress, and the Fructus Aurantii-Rhizoma Chuanxiong (ZQCX) decoction will be utilized to dock the MDD-FGID cluster.

METHODS/RESULTS

Here, Rhizoma Chuanxiong, one of the seven components of Chaihu-shugan-San, elicited the best antidepressant effect on CUMS rats, followed by Fructus Aurantii. ZQCX reversed AFS-induced depression-like behaviours and gastrointestinal dysmobility by regulating the glutamatergic system, AMPAR/BDNF/mTOR/synapsin I pathway, ghrelin signalling and gastrointestinal nitric oxide synthase. Based on the bioethnopharmacological analysis strategy, the determined meranzin hydrate (MH) and senkyunolide I (SI) by UPLC-PDA, simultaneously absorbed by the jejunum and hippocampus of rats, have been considered major absorbed bioactive compounds acting on behalf of ZQCX. Cotreatment with MH and SI at an equivalent dose in ZQCX synergistically replicated over 50.33 % efficacy of the parent formula in terms of antidepressant and prokinetic actions by modulating neuroinflammation and ghrelin signalling.

CONCLUSION

Brain-centric mind shifts require the integration of multiple central and peripheral systems and the elucidation of the underlying neurobiological mechanisms that ultimately contribute to novel therapeutic options. Ghrelin signalling and the immune system may partially underlie multimorbidity vulnerability, and ZQCX anchors stress-induced MDD-FGID clusters by docking them. Combining the results of micro details with the laws of the macro world may be more effective in finding treatments for MDD.

Guhan Yangsheng Jing mitigates hippocampal neuronal pyroptotic injury and manifies learning and memory capabilities in sleep deprived mice via the NLRP3/Caspase1/GSDMD signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Guhan Yangsheng Jing (GHYSJ) is a traditional Chinese patent medicine, that has the function of nourishing the kidney and replenishing the essence, invigorating the brain and calming the mind. It is often used to treat dizziness, memory loss, sleep disorders, fatigue, and weakness, etc. However, its mechanism for improving sleep has not yet been determined.

AIM OF THE STUDY

This study aims to explore the effects of GHYSJ on Sleep Deprivation (SD)-induced hippocampal neuronal pyroptotic injury, learning and cognitive abilities, and sleep quality in mice.

METHODS

In this study, a PCPA-induced SD mouse model was established. We assessed the influence of GHYSJ on sleep quality and mood by using the pentobarbital-induced sleep test (PIST) and sucrose preference test (SPT). The pharmacological effects of GHYSJ on learning and memory impairment were evaluated by the Morris Water Maze (MWM) and Open Field Test (OFT). Pathological changes in the hippocampal tissue of the SD rats were observed via HE staining and Nissl staining. The severity of neuronal damage was evaluated by detecting the expression of the neuronal marker Microtubule-associated protein 2 (MAP2), via immunohistochemistry and immunofluorescence. Furthermore, the levels of neurotransmitter 5-hydroxytryptophan (5-HTP), 5-hydroxy tryptamine (5-HT), γ-aminobutyric acid (GABA), and Glutamic acid (Glu) in hippocampal tissues, as well as the expression of inflammatory factors Interleukin-1β (IL-1β) and Interleukin-18 (IL-18) in serum, were determined by ELISA. The expressions of mRNA and protein NOD-like receptor thermal protein domain associated protein 3 (NLRP3), Gasdermin D (GSDMD), Cysteinyl aspartate specific proteinase1 (Caspase1), High mobility group box-1 protein (HMGB1) and Apoptosis-associated speck-like protein containing CARD (ASC) related to the cellular ferroptosis pathway were tested and analyzed by RT-PCR and WB respectively.

RESULTS

PCPA significantly diminishes the sleep span of experimental animals by expediting the expenditure of 5-HT, consequently establishing an essentially direct SD model. The intervention of GHYSJ displays remarkable efficacy in mitigating insomnia symptoms, encompassing difficulties in initiating sleep and insufficient sleep duration. Likewise, it ameliorates memory function impairments induced by sleep deprivation, along with symptoms such as fatigue and depletion of vitality. GHYSJ exerts a protective influence on hippocampal neurons facilitated by inhibiting the down regulation of MAP2 and maintaining the equilibrium of neurotransmitters (5-HTP, 5-HT, GABA, and Glu). It diminishes the expression of intracellular pyroptosis-associated inflammatory factors (IL-1β and IL-18) and curbs the activation of the NLRP3/Caspase1/GSDMD pyroptosis-related signaling pathways, thereby alleviating the damage caused by hippocampal neuronal pyroptosis.

Interpreting the Mechanism of Active Ingredients in Polygonati Rhizoma in Treating Depression by Combining Systemic Pharmacology and In Vitro Experiments

Polygonati Rhizoma (PR) has certain neuroprotective effects as a homology of medicine and food. In this study, systematic pharmacology, molecular docking, and in vitro experiments were integrated to verify the antidepressant active ingredients in PR and their mechanisms. A total of seven compounds in PR were found to be associated with 45 targets of depression. Preliminarily, DFV docking with cyclooxygenase 2 (COX2) showed good affinity. In vitro, DFV inhibited lipopolysaccharide (LPS)-induced inflammation of BV-2 cells, reversed amoeba-like morphological changes, and increased mitochondrial membrane potential. DFV reversed the malondialdehyde (MDA) overexpression and superoxide dismutase (SOD) expression inhibition in LPS-induced BV-2 cells and decreased interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6 mRNA expression levels in a dose-dependent manner. DFV inhibited both mRNA and protein expression levels of COX2 induced by LPS, and the activation of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) and caspase1 was suppressed, thus exerting an antidepressant effect. This study proves that DFV may be an important component basis for PR to play an antidepressant role.

The Impact of Prevotella on Neurobiology in Aging: Deciphering Dendritic Cell Activity and Inflammatory Dynamics

Prevotella species, notably Prevotella copri, significantly populate the human gut. In particular, P. copri is prevalent among non-Western populations with diets high in fiber. These species show complex relationships with diverse health aspects, associating with beneficial outcomes, including reduced visceral fat and improved glucose tolerance. Studies implicate various Prevotella species in specific diseases. Prevotella nigrescens and Porphyromonas gingivalis were linked to periodontal disease, promoting immune responses and influencing T helper type 17 (Th17) cells. Prevotella bivia was associated with bacterial vaginosis and a specific increase in activated cells in the vaginal mucosa. In contrast, they have shown substantial potential for inducing connective tissue degradation and alveolar bone resorption. Prevotella's role in neuroinflammatory disorders and autoinflammatory conditions such as Alzheimer's disease and Parkinson's disease has also been noted. The complex relationship between Prevotella and age-related conditions further extends to neurobiological changes in aging, with varying associations with Alzheimer's, Parkinson's, and other inflammatory conditions. Studies have also identified Prevotella to be implicated in cognitive decline in middle aged and the elderly. Future directions in this research area are anticipated to explore Prevotella-associated inflammatory mechanisms and therapeutic interventions. Investigating specific drug targets and immunomodulatory measures could lead to novel therapeutic strategies. Understanding how Prevotella-induced inflammation interacts with aging diseases would offer promising insights for treatments and interventions. This review urges ongoing research to discover therapeutic targets and mechanisms for moderating Prevotella-associated inflammation to further enhance our understanding and improve health outcomes.

Alpha-Asarone Ameliorates Neurological Dysfunction of Subarachnoid Hemorrhagic Rats in Both Acute and Recovery Phases via Regulating the CaMKII-Dependent Pathways

Early brain injury (EBI) is the leading cause of poor prognosis for patients suffering from subarachnoid hemorrhage (SAH), particularly learning and memory deficits in the repair phase. A recent report has involved calcium/calmodulin-dependent protein kinase II (CaMKII) in the pathophysiological process underlying SAH-induced EBI. Alpha-asarone (ASA), a major compound isolated from the Chinese medicinal herb Acorus tatarinowii Schott, was proven to reduce secondary brain injury by decreasing CaMKII over-phosphorylation in rats' model of intracerebral hemorrhage in our previous report. However, the effect of ASA on SAH remains unclear, and the role of CaMKII in both acute and recovery stages of SAH needs further investigation. In this work, we first established a classic SAH rat model by endovascular perforation and intraperitoneally administrated different ASA doses (10, 20, and 40 mg/kg) 2 h after successful modeling. Then, the short- and long-term neurobehavioral performances were blindly evaluated to confirm ASA's efficacy against SAH. Subsequently, we explored ASA's therapeutic mechanism in both acute and recovery stages using histopathological examination, TUNEL staining, flow cytometry, Western-blot, double-immunofluorescence staining, and transmission electron microscopy (TEM) observation. Finally, KN93, a selective CaMKII inhibitor, was applied in oxyhemoglobin-damaged HT22 cells to explore the role of CaMKII in ASA's neuroprotective effect. The results demonstrated that ASA alleviated short- and long-term neurological dysfunction, reduced mortality and seizure rate within 24 h, and prolonged 14-day survival in SAH rats. Histopathological examination showed a reduction of neuronal damage and a restoration of the hippocampal structure after ASA treatment in both acute and recovery phases of SAH. In the acute stage, the Western-blot and flow cytometer analyses showed that ASA restored E/I balance, reduced calcium overload and CaMKII phosphorylation, and inhibited mitochondrion-involved apoptosis, thus preventing neuronal damage and apoptosis underlying EBI post-SAH. In the recovery stage, the TEM observation, double-immunofluorescence staining, and Western-blot analyses indicated that ASA increased the numbers of synapses and enhanced synaptic plasticity in the ipsilateral hippocampi, probably by promoting NR2B/CaMKII interaction and activating subsequent CREB/BDNF/TrkB signaling pathways. Furthermore, KN93 notably reversed ASA's neuroprotective effect on oxyhemoglobin-damaged HT22 cells, confirming CaMKII a potential target for ASA's efficacy against SAH. Our study confirmed for the first time that ASA ameliorated the SAH rats' neurobehavioral deterioration, possibly via modulating CaMKII-involved pathways. These findings provided a promising candidate for the clinical treatment of SAH and shed light on future drug discovery against SAH.

Natural product Kaji-ichigoside F1 exhibits rapid antidepression via activating the AMPA-BDNF-mTOR pathway and inhibiting the NMDAR-CaMKIIα pathway

BACKGROUND

Depression is a common and recurrent neuropsychiatric disorder. Recent studies have shown that the N-methyl-d-aspartate (NMDA) receptor (NMDAR) is involved in the pathophysiology of depression. Previous studies have found that Kaji-ichigoside F1 (KF1) has a protective effect against NMDA-induced neurotoxicity. However, the antidepressant mechanism of KF1 has not been confirmed yet.

PURPOSE

In the present study, we aimed to evaluate the rapid antidepressant activity of KF1 and explore the underlying mechanism.

STUDY DESIGN

First, we explored the effect of KF1 on NMDA-induced hippocampal neurons and the underlying mechanism. Second, depression was induced in C57BL/6 mice via chronic unpredictable mild stress (CUMS), and the immediate and persistent depression-like behavior was evaluated using the forced swimming test (FST) after a single administration of KF1. Third, the contributions of NMDA signaling to the antidepressant effect of KF1 were investigated using pharmacological interventions. Fourth, CUMS mice were treated with KF1 for 21 days, and then their depression-like behaviors and the underlying mechanism were further explored.

METHODS

The FST was used to evaluate immediate and persistent depression-like behavior after a single administration of KF1 with or without NMDA pretreatment. The effect of KF1 on depressive-like behavior was investigated in CUMS mice by treating them with KF1 once daily for 21 days through the sucrose preference test, FST, open field test, and tail suspension test. Then, the effects of KF1 on the morphology and molecular and functional phenotypes of primary neuronal cells and hippocampus of mice were investigated by hematoxylin-eosin staining, Nissl staining, propidium iodide staining, TUNEL staining, Ca2+ imaging, JC-1 staining, ELISA, immunofluorescence analysis, RT-PCR, and Western blot.

RESULTS

KF1 could effectively improve cellular viability, reduce apoptosis, inhibit the release of LDH and Ca2+, and increase the mitochondrial membrane potential and the number of dendritic spines numbers in hippocampal neurons. Moreover, behavioral tests showed that KF1 exerted acute and sustained antidepressant-like effects by reducing Glu-levels and ameliorating neuronal damage in the hippocampus. Additionally, in vivo and in vitro experiments revealed that PSD95, Syn1, α-amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and brain-derived neurotrophic factor (BDNF) were upregulated at the protein level, and BDNF and AMPA were upregulated at the mRNA level. NR1 and NR2A showed the opposite trend.

CONCLUSION

These results confirm that KF1 exerts rapid antidepressant effects mainly by activating the AMPA-BDNF-mTOR pathway and inhibiting the NMDAR-CaMKIIα pathway. This study serves as a new reference for discovering rapid antidepressants.

Wenyang-Tianjing-Jieyu Decoction Improves Depression Rats of Kidney Yang Deficiency Pattern by Regulating T Cell Homeostasis and Inflammation Level

Purpose

Chronic inflammation is one of the key mechanisms of depression. Wenyang-Tianjin-Jie Decoction (WTJD) is an effective antidepressant found in the course of diagnosis and treatment, but the mechanism of therapeutic effect is not clear. The study aimed to evaluate the efficacy of WTJD in the kidney yang deficiency (KYD) type of depression rats and reveal its mechanisms.

Materials and Methods

We selected forty 6-week-old male Sprague-Dawley rats for the study. We established a KYD [Phellodendron amurense Rupr (Huangbai) solution oral gavage and 4°C environments; 8 weeks] type of depression (chronic unpredictable mild stimulus; 6 weeks) rat model first. After successful modeling, we used WTJD or fluoxetine on rats for 3 weeks. Then we evaluated the depression and KYD behavior. Finally, we observed the expression of key inflammatory factors and proteins in peripheral blood and hippocampus, and further investigated the immune balance of Th17/Treg and Th1/Th2 cells and the activity of their main regulatory pathways JAK2/STAT3 and TLR4/TRAF6/NF-κB.

Results

The imbalance of Th17/Treg and Th1/Th2 cells in rats were related to KYD and depressive symptoms. Through this study, we found that WTJD can inhibit the activity of JAK2/STAT3 and TLR4/TRAF6/NF-κB pathways, balance Th17/Treg and Th1/Th2 cell homeostasis, regulate the levels of inflammatory factors in the hippocampus and peripheral blood, and reverse KYD and depression.

Conclusion

This study confirmed that WTJD had a reliable effect on depression rats with KYD, and its mechanism was to regulate the immune homeostasis of hippocampal T cells and related inflammatory factors to improve KYD and depression symptoms in rats.

Human umbilical cord mesenchymal stem cells reverse depression in rats induced by chronic unpredictable mild stress combined with lipopolysaccharide

BACKGROUND

Inflammation and oxidative stress are considered crucial to the pathogenesis of depression. Rat models of depression can be created by combined treatments of chronic unpredictable mild stress (CUMS) and lipopolysaccharide (LPS). Behaviors associated with depression could be improved by treatment with mesenchymal stem cells (MSCs) owing to immunomodulatory functions of the cells. Therapeutic potentials of the MSCs to reverse pro-inflammatory cytokines, proteins, and metabolites were identified by transcriptomic, proteomic, and metabolomic analysis, respectively.

METHODS

A depression model was established in male SD rats by 2 weeks of CUMS combined with LPS. The models were verified by behavioral tests, namely SPT, OFT, EPM, and qRT-PCR for pro-inflammatory cytokines. Such depressed rats were administered human umbilical cord MSCs (hUC-MSCs) via the tail vein once a week for 2 and 4 weeks. The homing capacity was confirmed by detection of the fluorescent dye on day 7 after the hUC-MSCs were labeled with CM-Dil and administered. The expression of GFAP in astrocytes serves as a biomarker of CNS disorders and IBA1 in microglia serves as a marker of microglia activation were detected by immunohistochemistry at 2 and 4 weeks after final administration of hUC-MSCs. At the same time, transcriptomics of rat hippocampal tissue, proteomic and metabolomic analysis of the serum from the normal, depressed, and treated rats were also compared.

RESULTS

Reliable models of rat depression were successfully induced by treatments of CUMS combined with LPS. Rat depression behaviors, pro-inflammatory cytokines, and morphological disorders of the hippocampus associated with depression were reversed in 4 weeks by hUC-MSC treatment. hUC-MSCs could reach the hippocampus CA1 region through the blood circulation on day 7 after administration owing to the disruption of blood brain barrier (BBB) by microglial activation from depression. Differentiations of whole-genome expression, protein, and metabolite profiles between the normal and depression-modeled rats, which were analyzed by transcriptomic, proteomics, and metabolomics, further verified the high association with depression behaviors.

CONCLUSIONS

Rat depression can be reversed or recovered by treatment with hUC-MSCs.

Potential Role of Bmal1 in Lipopolysaccharide-Induced Depression-Like Behavior and its Associated "Inflammatory Storm"

Inflammation plays an important role in the pathogenesis of depression; however, the underlying mechanisms remain unclear. Apart from the disordered circadian rhythm in animal models and patients with depression, dysfunction of clock genes has been reported to be involved with the progress of inflammation. This study aimed to investigate the role of circadian clock genes, especially brain and muscle ARNT-like 1 (Bmal1), in the linkage between inflammation and depression. Lipopolysaccharide (LPS)-challenged rats and BV2 cells were used in the present study. Four intraperitoneal LPS injections of 0.5 mg/kg were administered once every other day to the rats, and BV2 cells were challenged with LPS for 24 h at the working concentration of 1 mg/L, with or without the suppression of Bmal1 via small interfering RNA. The results showed that LPS could successfully induce depression-like behaviors and an "inflammatory storm" in rats, as indicated by the increased immobility time in the forced swimming test and the decreased saccharin preference index in the saccharin preference test, together with hyperactivity of the hypothalamic-pituitary-adrenal axis, hyperactivation of astrocyte and microglia, and increased peripheral and central abundance of tumor necrosis factor-α, interleukin 6, and C-reactive protein. Moreover, the protein expression levels of brain-derived neurotrophic factor, triggering receptor expressed on myeloid cells 1, Copine6, and Synaptotagmin1 (Syt-1) decreased in the hippocampus and hypothalamus, whereas the expression of triggering receptor expressed on myeloid cells 2 increased. Interestingly, the fluctuation of temperature and serum concentration of melatonin and corticosterone was significantly different between the groups. Furthermore, protein expression levels of the circadian locomotor output cycles kaput, cryptochrome 2, and period 2 was significantly reduced in the hippocampus of LPS-challenged rats, whereas Bmal1 expression was significantly increased in the hippocampus but decreased in the hypothalamus, where it was co-located with neurons, microglia, and astrocytes. Consistently, apart from the reduced cell viability and increased phagocytic ability, LPS-challenged BV2 cells presented a similar trend with the changed protein expression in the hippocampus of the LPS model rats. However, the pathological changes in BV2 cells induced by LPS were reversed after the suppression of Bmal1. These results indicated that LPS could induce depression-like pathological changes, and the underlying mechanism might be partly associated with the imbalanced expression of Bmal1 and its regulated dysfunction of the circadian rhythm.

Chronic Treatment with Nigella sativa Oil Exerts Antimanic Properties and Reduces Brain Inflammation in Rats

Nigella sativa (NS) is a native herb consumed habitually in several countries worldwide, possessing manifold therapeutic properties. Among them, anti-inflammatory features have been reported, presumably relating to mechanisms involved in the nuclear factor kappa-B pathway, among others. Given the observed association between neuroimmune factors and mental illness, the primary aim of the present study was to examine the effects of chronic NS use on manic-like behavior in rats, as well as analyze levels of brain inflammatory mediators following NS intake. Using male and female rats, baseline tests were performed; thereafter, rats were fed either regular food (control) or NS-containing food (treatment) for four weeks. Following intervention, behavioral tests were induced (an open field test, sucrose consumption test, three-chamber sociality test, and amphetamine-induced hyperactivity test). Subsequently, brain samples were extracted, and inflammatory mediators were evaluated, including interleukin-6, leukotriene B4, prostaglandin E2, tumor necrosis factor-α, and nuclear phosphorylated-p65. Our findings show NS to result in a marked antimanic-like effect, in tandem with a positive modulation of select inflammatory mediators among male and female rats. The findings reinforce the proposed therapeutic advantages relating to NS ingestion.

P2X7 receptor inhibition prevents atrial fibrillation in rodent models of depression

AIMS

Depression, the most prevalent psychiatric disorder, is associated with the occurrence and development of atrial fibrillation (AF). P2X7 receptor (P2X7R) activation participates in the development of depression, but little attention has been given to its role in AF. This study was to investigate the effects of P2X7R on AF in depression models.

METHODS AND RESULTS

Lipopolysaccharide (LPS) and chronic unpredictable stress (CUS) were carried out to induce depression in rodents. Behavioural assessments, atrial electrophysiological parameters, electrocardiogram (ECG) parameters, western blot, and histology were performed. Atrial fibrillation inducibility was increased in both LPS- and CUS-induced depression, along with the up-regulation of P2X7R in atria. CUS facilitated atrial fibrosis. CUS reduced heart rate variability (HRV) and increased the expression of TH and GAP43, representing autonomic dysfunction. Down-regulation of Nav1.5, Cav1.2, Kv1.5, Kv4.3, Cx40, and Cx43 in CUS indicated the abnormalities in ion channels. In addition, the expression levels of TLR4, P65, P-P65, NLRP3, ASC, caspase-1, and IL-1β were elevated in depression models. Pharmacological inhibitor (Brilliant Blue G, BBG) or genetic deficiency of P2X7R significantly mitigated depressive-like behaviours; ameliorated electrophysiological deterioration and autonomic dysfunction; improved ion channel expression and atrial fibrosis; and prevented atrial NLRP3 inflammasome activation in the pathophysiological process of AF in depression models.

CONCLUSION

LPS or CUS induces AF and promotes P2X7R-dependent activation of NLRP3 inflammasome, whereas pharmacological P2X7R inhibition or P2X7R genetic deficiency prevents atrial remodelling without interrupting normal atrial physiological functions. Our results point to P2X7R as an important factor in the pathology of AF in depression.

MicroRNA-451a is a candidate biomarker and therapeutic target for major depressive disorder

Background

Increasing evidence supports the role of microRNAs (miRNAs) in major depressive disorder (MDD), but the pathophysiological mechanism remains elusive.

Aims

To explore the mechanism of microRNA-451a (miR-451a) in the pathology and behaviours of depression.

Methods

Abnormal miRNAs such as miR-451a reported previously in the serum of patients with MDD were screened and then confirmed in a mouse model of depression induced by chronic restraint stress (CRS). Eight-week-old male C57BL/6 mice had miR-451a overexpression in the medial prefrontal cortex (mPFC) via adeno-associated virus serotype 9 vectors encoding a pri-mmu-miR-451a-GFP fusion protein followed by behavioural and pathological analyses. Finally, molecular biological experiments were conducted to investigate the potential mechanism of miR-451a against depression.

Results

The serum levels of miRNA-451a were significantly lower in patients with MDD, with a negative correlation with the Hamilton Depression Scale scores. Additionally, a negative association between serum miR-451a and behavioural despair or anhedonia was observed in CRS mice. Notably, miR-451a expression was significantly downregulated in the mPFC of CRS-susceptible mice. Overexpressing miR-451a in the mPFC reversed the loss of dendritic spines and the depression-like phenotype of CRS mice. Mechanistically, miR-451a could inhibit CRS-induced corticotropin-releasing factor receptor 1 expression via targeting transcription factor 2, subsequently protecting dendritic spine plasticity.

Conclusions

Together, these results highlighted miR-451a as a candidate biomarker and therapeutic target for MDD.

The antidepressive mechanism of Longya Lilium combined with Fluoxetine in mice with depression-like behaviors

Traditional Chinese medicine is one of the most commonly used complementary and alternative medicine therapies for depression. Integrated Chinese-western therapies have been extensively applied in numerous diseases due to their superior efficiency in individual treatment. We used the meta-analysis, network pharmacology, and bioinformatics studies to identify the putative role of Longya Lilium combined with Fluoxetine in depression. Depression-like behaviors were mimicked in mice after exposure to the chronic unpredictable mild stress (CUMS). The underlying potential mechanism of this combination therapy was further explored based on in vitro and in vivo experiments to analyze the expression of COX-2, PGE2, and IL-22, activation of microglial cells, and neuron viability and apoptosis in the hippocampus. The antidepressant effect was noted for the combination of Longya Lilium with Fluoxetine in mice compared to a single treatment. COX-2 was mainly expressed in hippocampal CA1 areas. Longya Lilium combined with Fluoxetine reduced the expression of COX-2 and thus alleviated depression-like behavior and neuroinflammation in mice. A decrease of COX-2 curtailed BV-2 microglial cell activation, inflammation, and neuron apoptosis by blunting the PGE2/IL-22 axis. Therefore, a combination of Longya Lilium with Fluoxetine inactivates the COX-2/PGE2/IL-22 axis, consequently relieving the neuroinflammatory response and the resultant depression.

Merazin hydrate produces rapid antidepressant effects by activating CaMKII to promote neuronal activities and proliferation in hippocampus

In our previous studies, we demonstrated that merazin hydrate (MH) had rapid antidepressant effects, but the deep mechanism needed to be further investigated. In this study, we used depressive-like model, behavioral tests, molecular biology and pharmacological interventions to reveal the underlying mechanisms of MH's rapid antidepressants. We found that a single administration of MH was able to produce rapid antidepressant effects in chronic unpredictable mild stress (CUMS) exposed mice at 1 day later, similar to ketamine. Moreover, MH could not only significantly up-regulated the expressions of cFOS, but also obviously increased the number of Ki67 positive cells in hippocampal dentate gyrus (DG). Furthermore, we also found that the phosphorylated expression of calcium/calmodulin-dependent protein kinase II (CaMKII) was significantly reduced by CUMS in hippocampus, which was also reversed by MH. In addition, pharmacological inhibition of CaMKII by using KN-93 (a CaMKII antagonist) blocked the MH's up-regulation of cFOS and Ki67 in hippocampal DG. To sum up, this study demonstrated that MH produced rapid antidepressant effects by activating CaMKII to promote neuronal activities and proliferation in hippocampus.

Interplay of G-proteins and Serotonin in the Neuroimmunoinflammatory Model of Chronic Stress and Depression: A Narrative Review

INTRODUCTION

This narrative review addresses the clinical challenges in stress-related disorders such as depression, focusing on the interplay between neuron-specific and pro-inflammatory mechanisms at the cellular, cerebral, and systemic levels.

OBJECTIVE

We aim to elucidate the molecular mechanisms linking chronic psychological stress with low-grade neuroinflammation in key brain regions, particularly focusing on the roles of G proteins and serotonin (5-HT) receptors.

METHODS

This comprehensive review of the literature employs systematic, narrative, and scoping review methodologies, combined with systemic approaches to general pathology. It synthesizes current research on shared signaling pathways involved in stress responses and neuroinflammation, including calcium-dependent mechanisms, mitogen-activated protein kinases, and key transcription factors like NF-κB and p53. The review also focuses on the role of G protein-coupled neurotransmitter receptors (GPCRs) in immune and pro-inflammatory responses, with a detailed analysis of how 13 of 14 types of human 5-HT receptors contribute to depression and neuroinflammation.

RESULTS

The review reveals a complex interaction between neurotransmitter signals and immunoinflammatory responses in stress-related pathologies. It highlights the role of GPCRs and canonical inflammatory mediators in influencing both pathological and physiological processes in nervous tissue.

CONCLUSION

The proposed Neuroimmunoinflammatory Stress Model (NIIS Model) suggests that proinflammatory signaling pathways, mediated by metabotropic and ionotropic neurotransmitter receptors, are crucial for maintaining neuronal homeostasis. Chronic mental stress can disrupt this balance, leading to increased pro-inflammatory states in the brain and contributing to neuropsychiatric and psychosomatic disorders, including depression. This model integrates traditional theories on depression pathogenesis, offering a comprehensive understanding of the multifaceted nature of the condition.

Effects of aerobic exercise on depression-like behavior and TLR4/NLRP3 pathway in hippocampus CA1 region of CUMS-depressed mice

BACKGROUND AND PURPOSE

The paper observes regulation of the expression levels of NLRP3 and TLR4 in hippocampal CA1 neurons in CUMS mice by aerobic exercise with constructing CUMS depression mouse model, in order to explore the neuroprotective mechanism of aerobic exercise on the hippocampus of depressed mice.

STUDY DESIGN AND METHOD

24 healthy male 8-week-old C57BL/6 mice were randomly divided into CG, MG and ME. Thirteen stress-stimulating factors were randomly formulated into a CUMS stress-stimulating program. The mice were underwent 28 days of CUMS depression model, referenced clinical means for experimental research. The study was approved by the Ethics Committee of Yichun University (YCUEC IRB number LSK NO.2022.18). After model preparation, ME mice were subjected to moderate-intensity treadmill exercise training for 8 weeks. TST, FST and SPT were used to detect the depression-like behaviors of the mice in each group. Nissl staining was used to compare the cell morphology in the CA1 region of the mouse hippocampus. Immunohistochemical staining and western blot were used to detect the changes in the expression levels of NLRP3, TLR4 and other proteins in the CA1 region of the mouse hippocampus.

RESULTS

The results of neurobehavioral assessment showed that, the immobility time of TST and FST were significantly increased, and SPT index was significantly decreased of MG mice. Compared with MG, ME mice significantly improved depression-like behaviors such as TST, FST and SPT index. Nissl staining showed that the morphology of neurons in CA1 region of hippocampus of MG mice were mostly vacuolar-like, with severe nuclear pyknosis. Abnormal morphological changes such as vacuolar-like and pyknotic pyknosis of neurons in the hippocampal CA1 region of ME mice were significantly reduced. Protein expression test showed that the number of NLRP3, TLR4, IL-1β and IL-10 positive neurons in hippocampal CA1 region of MG mice increased significantly compared with CG, and the proportion of positive cells increased significantly, while NLRP3 and TLR4 positive neurons in the hippocampal CA1 region of ME mice were significantly reduced, the proportion of TLR4 positive cells was significantly reduced.

CONCLUSION

Systematic moderate-intensity exercise can effectively improve the depression-like behavior of CUMS depressed mice through the expression of TLR4/NLRP3 inflammatory signaling pathway, and provide an effective experimental basis for the clinical rehabilitation treatment of depression.

The effect of acupuncture on lateral habenular nucleus and intestinal microflora in depression model rats

BACKGROUND

Depression is a severe emotional condition that significantly affects the quality of life. Acupuncture exerts preventive effects on depression in rats with post-chronic unpredictable mild stress (CUMS). Methods The study involved chronic unpredictable mild stress (CUMS) depression model mice to administer acupuncture as a preventative measure to investigate the mechanism of acupuncture's antidepressant and observe the effect of acupuncture on impact via the Lateral Habenula (LHb) and Gut-Liver-Brain Axis. The researcher investigated molecules correlating with a nitric oxide/cyclic guanosine monophosphate (NO/cGMP) pathway and assessed inflammation in the LHb and liver. In addition, 16 S rDNA bioinformatics study revealed the quantity and variety of gut microbiota. Rats were randomly divided into five groups: control (CON), CUMS, CUMS + acupuncture (AP), CUMS + fluoxetine (FX) and CUMS + N(G) -nitro -L- arginine methyl ester (LNAME) group. Except for the CON group, other rats were exposed to CUMS condition for 28 days. Simultaneously, manual acupuncture (at Fengfu and Shangxing acupoints, once every other day) and fluoxetine gavage (2.1 mg/kg, 0.21 mg/mL, daily) were conducted to the groups of AP and FX, respectively, after stressors. Rats in LNAME group were treated with LNAME normal saline (10 mg/kg, 1 mg/mL, i.p.) solution. Behavioural tests and biological detection methods were conducted sequentially to evaluate depressionlike phenotype in rats.

RESULTS

The results showed CUMS induced depression-like behaviours, hyper-activation of NO/cGMP signaling pathway, inflammation in serum, LHb and liver, and dysbiosis of the gut microbiota. These changes could be prevented and ameliorated by acupuncture to varying extents.

CONCLUSION

Acupuncture prevented and attenuated depression-like phenotype induced by CUMS, possibly via regulating the NO/cGMP signaling pathway and thus improving inflammation in serum, LHb and liver, and gut microbiota dysbiosis. In addition, these can be evidence of the existence of the gut-liver-brain axis.

The role of ROS/p38 MAPK/NLRP3 inflammasome cascade in arsenic-induced depression-/anxiety-like behaviors of mice

Arsenic pollution in groundwater remains a serious public health concern around the world. Recent years, arsenic-related neurological and psychiatric disorders have been reported increasingly. However, the exact mechanisms of it remains elusive. In this study, arsenic exposure through drinking water resulted in depression-/anxiety-like behaviors in mice accompanied by oxidative stress and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome activation in prefrontal cortex (PFC) and hippocampus, two main affected areas found in neurobehavioral disorders. Intervention by NAC, a ROS scavenger, diminished the social behavior impairments in mice as well as ROS generation and NLRP3 inflammasome activation. Further study revealed that it was p38 MAPK signaling pathway that mediated ROS-induced NLRP3 inflammasome activation. Overall, our findings suggested that ROS/p38 MAPK/NLRP3 inflammasome cascade was involved in arsenic-induced depression-/anxiety-disorders. Furthermore, NAC might be a potential therapeutic agent for arsenic-induced depression-/anxiety-disorders by inhibiting both ROS generation and ROS-induced NLRP3 inflammasome activation.

A terrified-sound stress causes cognitive impairment in female mice by impairing neuronal plasticity

Stress is an important environmental factor affecting mental health that cannot be ignored. Moreover, due to the great physiological differences between males and females, the effects of stress may vary by sex. Previous studies have shown that terrified-sound stress, meaning exposed mice to the recorded vocalizations in response to the electric shock by their kind to induce psychological stress, can cause cognitive impairment in male. In the study, we investigated the effects of the terrified-sound stress on adult female mice.

METHODS

32 adults female C57BL/6 mice were randomly divided into control (n = 16) and stress group (n = 16). Sucrose preference test (SPT)was carried out to evaluate the depressive-like behavior. Using Open field test (OFT) to evaluate locomotor and exploratory alterations in mice. Spatial learning and memory ability were measured in Morris Water maze test (MWM), Golgi staining and western blotting showed dendritic remodeling after stress. In addition, serum hormone quantifications were performed by ELISA.

RESULTS

we found the sucrose preference of stress group was significantly decreased (p < 0.05) compared with control group; the escape latency of the stress group was significantly prolonged (p < 0.05), the total swimming distance and the number of target crossings(p < 0.05) were significantly increased (p < 0.05) in MWM; Endocrine hormone, Testosterone (T) (p < 0.05), GnRH (p < 0.05), FSH and LH levels was decreased; Golgi staining and western blotting showed a significant decrease in dendritic arborization, spine density and synaptic plasticity related proteins PSD95 and BDNF in the stress group.

CONCLUSION

Terrified-sound stress induced depressive-like behaviors, locomotor and exploratory alterations. And impaired cognitive by altering dendritic remodeling and the expression of synaptic plasticity-related proteins. However, females are resilient to terrified-sound stress from a hormonal point of view.

A new perspective on hippocampal synaptic plasticity and post-stroke depression

Post-stroke depression, a common complication after stroke, severely affects the recovery and quality of life of patients with stroke. Owing to its complex mechanisms, post-stroke depression treatment remains highly challenging. Hippocampal synaptic plasticity is one of the key factors leading to post-stroke depression; however, the precise molecular mechanisms remain unclear. Numerous studies have found that neurotrophic factors, protein kinases and neurotransmitters influence depressive behaviour by modulating hippocampal synaptic plasticity. This review further elaborates on the role of hippocampal synaptic plasticity in post-stroke depression by summarizing recent research and analysing possible molecular mechanisms. Evidence for the correlation between hippocampal mechanisms and post-stroke depression helps to better understand the pathological process of post-stroke depression and improve its treatment.

Investigation of the shared molecular mechanisms and hub genes between myocardial infarction and depression

Background

The pathogenesis of myocardial infarction complicating depression is still not fully understood. Bioinformatics is an effective method to study the shared pathogenesis of multiple diseases and has important application value in myocardial infarction complicating depression.

Methods

The differentially expressed genes (DEGs) between control group and myocardial infarction group (M-DEGs), control group and depression group (D-DEGs) were identified in the training set. M-DEGs and D-DEGs were intersected to obtain DEGs shared by the two diseases (S-DEGs). The GO, KEGG, GSEA and correlation analysis were conducted to analyze the function of DEGs. The biological function differences of myocardial infarction and depression were analyzed by GSVA and immune cell infiltration analysis. Four machine learning methods, nomogram, ROC analysis, calibration curve and decision curve were conducted to identify hub S-DEGs and predict depression risk. The unsupervised cluster analysis was constructed to identify myocardial infarction molecular subtype clusters based on hub S-DEGs. Finally, the value of these genes was verified in the validation set, and blood samples were collected for RT-qPCR experiments to further verify the changes in expression levels of these genes in myocardial infarction and depression.

Results

A total of 803 M-DEGs, 214 D-DEGs, 13 S-DEGs and 6 hub S-DEGs (CD24, CSTA, EXTL3, RPS7, SLC25A5 and ZMAT3) were obtained in the training set and they were all involved in immune inflammatory response. The GSVA and immune cell infiltration analysis results also suggested that immune inflammation may be the shared pathogenesis of myocardial infarction and depression. The diagnostic models based on 6 hub S-DEGs found that these genes showed satisfactory combined diagnostic performance for depression. Then, two molecular subtypes clusters of myocardial infarction were identified, many differences in immune inflammation related-biological functions were found between them, and the hub S-DEGs had satisfactory molecular subtypes identification performance. Finally, the analysis results of the validation set further confirmed the value of these hub genes, and the RT-qPCR results of blood samples further confirmed the expression levels of these hub genes in myocardial infarction and depression.

Conclusion

Immune inflammation may be the shared pathogenesis of myocardial infarction and depression. Meanwhile, hub S-DEGs may be potential biomarkers for the diagnosis and molecular subtype identification of myocardial infarction and depression.

Ginsenoside-Rg1 synergized with voluntary running exercise protects against glial activation and dysregulation of neuronal plasticity in depression

Depression is a common psychological disease accompanied by mental disorders and somatic symptoms. However, the underlying mechanisms regarding the pathogenesis of depression are still not clear. Neuronal damage resulting from inflammation is considered to be one of the important risk factors for depression. Ginsenoside-Rg1, a sterol extract extracted from ginseng herbs, has been shown to have neuroprotective effects against neurodegenerative diseases. Moreover, running exercise, a simple behavioral therapy, has been recently shown to have antidepressant effects. However, whether these two synergized strategies are more efficient in depression treatment, especially the neural mechanisms underlying this practical and interesting treatment is unknown. In this study, we have shown that ginsenoside-Rg1 synergized with voluntary running exercise exerts more efficiency on suppressing neuroinflammation, up-regulating expression of neurotrophic factors, and synaptic-related proteins, ameliorating neuronal structural damages than that of ginsenoside-Rg1 or voluntary exercise alone, suggesting its better neuroprotective effects. More importantly, the antidepressant-like effect of this synergistic treatment was also significantly better than either of these two treatments. These results suggest that ginsenoside-Rg1, synergized with voluntary running, may have higher efficacy in the treatment of depression through anti-inflammation and the improvement of neuroplasticity. These findings may provide a new perspective for the development of a therapeutic strategy for depression.

Antidepressant-like effects of geniposide in chronic unpredictable mild stress-induced mice by regulating the circ_0008405/miR-25-3p/Gata2 and Oip5os1/miR-25-3p/Gata2 networks

Evidence exists suggesting the anti-depressive activities of geniposide (GP), a major compound in Gardenia jasminoides Ellis. Accordingly, the present study attempts to explore the anti-depressive mechanism of GP in chronic unpredictable mild stress (CUMS)-induced depression-like behaviors of mice. CUMS-induced mice were given GP daily and subjected to behavioral tests to observe the effect of GP on the depression-like behaviors. It was noted that GP administration reduced depression-like behaviors in CUMS mice. Transcriptome sequencing was conducted in three control and three CUMS mice. Differentially expressed circRNAs, lncRNAs and mRNAs were then screened by bioinformatics analyses. Intersection analysis of the transcriptome sequencing results with the bioinformatics analysis results was followed to identify the candidate targets. We found that Gata2 alleviated depression-like behaviors via the metabolism- and synapse-related pathways. Gata2 was a target of miR-25-3p, which had binding sites to circ_0008405 and Oip5os1. circ_0008405 and Oip5os1 competitively bound to miR-25-3p to release the expression of Gata2. GP administration ameliorated depression-like behaviors in CUMS mice through regulation of the circ_0008405/miR-25-3p/Gata2 and Oip5os1/miR-25-3p/Gata2 crosstalk networks. Taken together, GP may exert a potential antidepressant-like effect on CUMS mice, which is ascribed to regulation of the circ_0008405/miR-25-3p/Gata2 and Oip5os1/miR-25-3p/Gata2 crosstalk networks.

Assessment of bidirectional relationships between depression and rheumatoid arthritis among adults: a two-sample Mendelian randomization study

OBJECTIVE

Increasing evidence shows that depression is associated with rheumatoid arthritis (RA). However, the causality and direction of this association remain unclear, because links between the two diseases might be caused by shared environmental confounding factors. Our study aims to understand a putative causal link between the two diseases.

METHODS

We retrieved summary statistics from meta-analyses of non-overlapping genome-wide association studies (GWASes) for depression (n = 807,553, 246,363 cases and 561,190 controls) and RA (n = 58,284, 14,361 cases and 42,923 controls). We combined Mendelian randomization (MR) estimates from each genetic instrument using inverse-variance weighted (IVW) meta-analysis, with alternate methods (e.g., simple median approach, weighted median approach, and MR-Egger regression) and conducted sensitivity analyses to assess the robustness of MR analyses.

RESULTS

We found no evidence of causal relationships between depression and RA across all MR methods (IVW OR, 1.028 for RA; 95% CI, 0.821-1.287; P = 0.810) or vice versa (IVW OR, 0.999 for depression; 95% CI, 0.984-1.014; P = 0.932), indicating the links between the two diseases might be due to confounders.

CONCLUSION

Despite the results, to optimize treatment outcomes of RA patients, we still emphasize depression should be managed as part of routine clinical care to optimize treatment outcomes of RA.

Lactobacillus reuteri strain 8008 attenuated the aggravation of depressive-like behavior induced by CUMS in high-fat diet-fed mice through regulating the gut microbiota

Objective: Gut microbiota play a key role in the pathogenesis of obesity and depression. Probiotics are a preventive strategy for obesity and a novel treatment for depression symptoms. However, the ameliorative or therapeutic effect of potential probiotic candidate Lactobacillus reuteri (L. reuteri) on obesity and depression comorbidity still remains unclear. We investigated the effects of chronic unpredictable mild stress (CUMS) in high-fat diet-fed mice and the effects of Lactobacillus reuteri strain 8008 on various disease indicators of obesity and depression comorbidity disease. Methods: Forty male C57BL/6 mice were randomized into 2 groups: the normal control (NC) group (n = 10) and the high-fat diet (HFD) group (n = 30), being fed with normal diet (ND) or high-fat diet (HFD) for 8 weeks, respectively. Then the obese mice fed with HFD were randomly allocated into 3 sub-groups: the HFD group (n = 10); the HFD + CUMS group (n = 10); the HFD + CUMS + L.r group (n = 10). The latter 2 subgroups underwent CUMS for 4 weeks to build the obesity and depression comorbidity mice model. During the duration of treatment, mice were gavaged with 0.5 mL PBS solution or L. reuteri (2 × 109 CFU/mL) once a day, respectively. The body weight, food intake, organ weight, behavioral indicators, histology, blood lipids, levels of inflammatory cytokines and tight junction proteins and abundance of colonic contents bacteria were measured. Results: The obesity and depression comorbidity mice model was successfully established after HFD feeding and chronic stress. The comorbid mice demonstrated inflammatory responses increase in liver and adipose tissues, worsened damage to the intestinal barrier as well as gut microbiota disorder. Gavaged with L. reuteri attenuated depressive-like behavior, improved blood lipids and insulin resistance, reduced inflammation in liver and adipose tissues, improved intestinal tight junctions as well as the microbiome dysbiosis in obesity and depression comorbidity mice. Conclusion: Lactobacillus reuteri strain 8008 could alleviate depressive-like behaviors and related indicators of obesity disorders by regulating the gut microbiota in obesity and depression comorbid mice.

Shared genetics of psychiatric disorders and type 2 diabetes:a large-scale genome-wide cross-trait analysis

BACKGROUND

Individuals with psychiatric disorders have elevated rates of type 2 diabetes comorbidity. Although little is known about the shared genetics and causality of this association. Thus, we aimed to investigate shared genetics and causal link between different type 2 diabetes and psychiatric disorders.

METHODS

We conducted a large-scale genome-wide cross-trait association study(GWAS) to investigate genetic overlap between type 2 diabetes and anorexia nervosa, attention deficit/hyperactivity disorder, autism spectrum disorder, bipolar disorder, major depressive disorder, obsessive-compulsive disorder, schizophrenia, anxiety disorders and Tourette syndrome. By post-GWAS functional analysis, we identify variants genes expression in various tissues. Enrichment pathways, potential protein interaction and mendelian randomization also provided to research the relationship between type 2 diabetes and psychiatric disorders.

RESULTS

We discovered that type 2 diabetes and psychiatric disorders had a significant correlation. We identified 138 related loci, 32 were novel loci. Post-GWAS analysis revealed that 86 differentially expressed genes were located in different brain regions and peripheral blood in type 2 diabetes and related psychiatric disorders. MAPK signaling pathway plays an important role in neural development and insulin signaling. In addition, there is a causal relationship between T2D and mental disorders. In PPI analysis, the central genes of the DEG PPI network were FTO and TCF7L2.

CONCLUSION

This large-scale genome-wide cross-trait analysis identified shared genetics andpotential causal links between type 2 diabetes and related psychiatric disorders, suggesting potential new biological functions in common among them.

Hybrid molecules combining GABA-A and serotonin 5-HT6 receptors activity designed to tackle neuroinflammation associated with depression

There is clear evidence that the presence of inflammatory factors and impaired GABA-ergic neurotransmission in depressed patients is associated with poor clinical outcome. We designed hybrid molecules, bearing the GABA molecule assembled with chemical fragments that interact with the serotonin 5-HT₆ receptor. Such a combination aimed to curb neuroinflammation, remodel GABA-ergic signaling, and provide antidepressant-like activity. The most promising hybrid 3B exerted nanomolar affinity for 5-HT₆ receptors and exerted agonistic properties on GABA-A receptors. Developability studies conferred that 3B exerted favorable drug-like properties and optimal brain penetration. In in vivo studies, 3B exerted robust antidepressant-like activity and proved to be highly effective in reducing levels of oxidative stress markers and the pro-inflammatory cytokine IL-6. The inetersting pharmacological profile of 3B makes it a promising candidate for further development for depression associated with neuroinflammation.

Microglia activation in the hippocampus mediates retinal degeneration-induced depressive-like behaviors via the NLRP3/IL-1β pathway

Epidemiological studies have shown that patients with glaucoma are more prone to depression, but the mechanism of comorbid depression in patients with glaucoma remains unknown. Excessive neuroinflammation has been shown to participate in glaucoma-induced retinal degeneration and hippocampal neural apoptosis in depression. However, little research has been conducted to determine whether neuroinflammation contributes to glaucoma-induced depression. Since the degeneration of retinal ganglion cells is a hallmark of glaucoma, we investigated the role of microglia-induced neuroinflammation in retinal degeneration-induced depression and its potential mechanism. An N-methyl-D-aspartate (NMDA)-induced retinal degeneration model was established, and behavioral tests were conducted at 3, 7, 14, and 21 days after retinal degeneration. After tissue collection, we used immunohistochemistry to assess the activation of microglia and real-time polymerase chain reaction to measure the levels of pro-inflammatory cytokines and the NOD-, LRR-, and pyrin-domain containing protein 3 (NLRP3) inflammasome. The mice exhibited depressive-like behaviors 14 and 21 days after retinal degeneration, based on the open field test, tail suspension test, and forced swimming test. Mice also displayed a lower body weight gain than the control group. In addition, microglial activation was observed in the hippocampus. Microglial proliferation was first observed in the dentate gyrus on day 3, while the number of microglia in cornu ammonis 1 grew the most. Moreover, not only was the expression of pro-inflammatory cytokines, including interleukin-1β, interleukin-18, and interleukin-6 promoted, but the messenger ribonucleic acid levels of the NLRP3 inflammasome were also increased. In conclusion, our research shows that NMDA-induced retinal degeneration can induce depressive-like behaviors, which may be attributed to hippocampal neuroinflammation.

Unique brain endothelial profiles activated by social stress promote cell adhesion, prostaglandin E2 signaling, hypothalamic-pituitary-adrenal axis modulation, and anxiety

Chronic stress may precipitate psychiatric disorders including anxiety. We reported that Repeated Social Defeat (RSD) in mice increased accumulation of inflammatory monocytes within the brain vasculature, which corresponded with increased interleukin (IL)-1 Receptor 1-mediated activation of endothelia, and augmented anxiety-like behavior. One unknown, however, is the role of immune-activated endothelia in regulating the physiological and behavioral responses to social stress. Thus, we sought to determine the RNA profile of activated endothelia and delineate the pathways by which these endothelia communicate within the brain to influence key responses to social stress. First, endothelial-specific RiboTag mice were exposed to RSD and brain endothelial mRNA profiles from the whole brain and prefrontal cortex were determined using RNAseq. RSD increased expression of cell adhesion molecules (Icam1), inflammatory genes (Lrg1, Lcn2, Ackr1, Il1r1), and cyclooxygenase-2 (Ptgs2/COX-2). In studies with IL-1R1KO mice, there was clear dependence on IL-1R1 on endothelia-associated transcripts including Lrg1, Icam1, Lcn2. Moreover, prostaglandin (PG)E2 was increased in the brain after RSD and Ptgs2 was localized to endothelia, especially within the hypothalamus. Next, a selective COX-2 inhibitor, Celecoxib (CCB), was used with social stress. RSD increased PGE2 in the brain and this was abrogated by CCB. Moreover, CCB reduced RSD-induced Hypothalamic-Pituitary-Adrenal (HPA) axis activation with attenuation of hypothalamic paraventricular neuron activation, hypothalamic Crh expression, and corticosterone in circulation. Production, release, and accumulation of inflammatory monocytes after RSD was COX-2 independent. Nonetheless, CCB blocked anxiety-like behavior in response to RSD. Collectively, social stress stimulated specific endothelia RNA profiles associated with increased cell adhesion, IL-1 and prostaglandin signaling, HPA axis activation, and anxiety.

Hippocampal microRNA-26a-3p deficit contributes to neuroinflammation and behavioral disorders via p38 MAPK signaling pathway in rats

BACKGROUND

Neuronal injury is considered a critical risk factor in the pathogenesis of most neurological and neuropsychiatric diseases. However, the underlying molecular mechanisms and identification of potential therapeutic targets for preventing neuronal injury associated with brain function remain largely uncharacterized. Therefore, identifying neural mechanisms would put new insights into the progression of this condition and provide novel therapeutic strategies for the treatment of these diseases.

METHODS

Stereotactic injection of AAV virus was used to knock-down the miR-26a-3p within hippocampus of rats. Behavioral changes was detected by open field test (OFT), elevated plus maze (EPM), forced swim test (FST) and sucrose preference test (SPT). The inflammatory cytokines and related proteins were verified by real-time quantitative PCR, immunoblotting or immunofluorescence assay. Golgi staining and electron microscopy analysis was used to observe the dendritic spine, synapse and ultrastructural pathology. SB203580 (0.5 mg/kg) were administered daily to prevent p38 MAPK via an intraperitoneal (i.p.) injection. Finally, electrophysiological method was used to examine the synaptic transmission via whole-cell patch-clamp recording.

RESULTS

Here, we showed that miR-26a-3p deficiency within hippocampal regions leads to the activation of microglia, increased level of pro-inflammatory cytokines and behavioral disorders in rats, effects which appear to be mediated by directly targeting the p38 mitogen-activated protein kinase (MAPK)-NF-κB signaling pathway. Specifically, we found that the enhanced glia-activation may consequently result in neuronal deterioration that mainly presented as the dysregulation of structural and functional plasticity in hippocampal neurons. In contrast, preventing p38 pathway by SB203580 significantly ameliorated abnormal behavioral phenotypes and neuronal jury resulting from miR-26a-3p knock-down.

CONCLUSION

These results suggest that the normal expression of miR-26a-3p exerts neuroprotective effects via suppressing neural abnormality and maintaining neuroplasticity to against behavioral disorders in rats. These effects appear to involve a down-regulation of p38 MAPK-NF-κB signaling within the hippocampal region. Taken together, these findings provide evidence that miR-26a-3p can function as a critical factor in regulating neural activity and suggest that the maintaining of normal structure and function of neurons might be a potential therapeutic strategy in the treatment of neurological disorders.

Rapid Eye Movement Sleep Deprivation Enhances Adenosine Receptor Activation and the CREB1/YAP1/c-Myc Axis to Alleviate Depressive-like Behaviors in Rats

As neuromodulators, adenosine and its receptors are mediators of sleep-wake regulation. A putative correlation between CREB1 and depression has been predicted in our bioinformatics analyses, and its expression was also predicted to be upregulated in response to sleep deprivation. Therefore, this study aims to elaborate the A1 and A2A adenosine receptors and CREB1-associated mechanism underlying the antidepressant effect of rapid eye movement sleep deprivation (REMSD) in rats with chronic unpredictable mild stress (CUMS)-induced depressive-like behaviors. The modeled rats were injected with adenosine A1 receptor antagonist DPCPX or adenosine A2A receptor antagonist ZM241385 to assess the role of adenosine receptors in depression. In addition, ectopic expression and depletion experiments of CREB1 and YAP1 were also conducted in vivo and in vitro. It was found that REMSD alleviated depressive-like behaviors in CUMS rats, as shown by increased spontaneous activity, sucrose consumption and percentage, and shortened escape latency and immobility duration. Meanwhile, A1 or A2A adenosine receptor antagonists negated the antidepressant effect of REMSD. REMSD enhanced adenosine receptor activation and promoted the phosphorylation of CREB1, thus increasing the expression of CREB1. In addition, the overexpression of CREB1 activated the YAP1/c-Myc axis and consequently alleviated depressive-like behaviors. Collectively, our results provide new mechanistic insights for an understanding of the antidepressant effect of REMSD, which is associated with the activation of adenosine receptors and the CREB1/YAP1/c-Myc axis.

Depressive-like behaviors induced by chronic cerebral hypoperfusion associate with a dynamic change of GABAB1/B2 receptors expression in hippocampal CA1 region

Cerebral ischemia could induce depressive-like behaviors; however, the alteration of gamma-aminobutyric acid receptors type B (GABA_B) receptors in these pathological processes has not been extensively investigated. The aim of the current study was to document the behavioral change and the alteration of GABA_B receptors in chronic cerebral hypoperfusion. The permanent occlusion of the bilateral common carotid arteries (two-vessel occlusion, 2VO) was performed to induce chronic cerebral ischemia (CCH). The depressive-like behaviors were evaluated with sucrose preference test, novelty suppress feeding test as well as forced swim test at 4, 8, and 12 weeks after the 2VO surgery. The total, surface and intracellular expressions of GABA_B subunit 1 (GABA_B1) and subunit 2 (GABA_B2) in hippocampal CA1 were quantified by western blot. The depressive-like behaviors were observed in rats suffered from 4, 8, and 12 weeks 2VO in sucrose preference test, novelty suppress feeding test and forced swim test. In addition, the surface and total expression of GABA_B1 in CA1 was reduced at 4 weeks after 2VO rather than 8 or 12 weeks. While the surface and total expression of GABA_B2 in CA1 was decreased throughout the ischemia timeline (4, 8, and 12 weeks). Taken together, our findings suggested the potential roles of GABA_B1 and GABA_B2 subunits involved in depressive-like behaviors caused by chronic cerebral hypoperfusion.

Saikosaponin D exerts antidepressant effect by regulating Homer1-mGluR5 and mTOR signaling in a rat model of chronic unpredictable mild stress

BACKGROUND

Many studies about depression have focused on the dysfunctional synaptic signaling in the hippocampus that drives the pathophysiology of depression. Radix Bupleuri has been used in China for over 2000 years to regulate liver-qi. Extracted from Radix Bupleuri, Saikosaponin D (SSD) is a pharmacologically active substance that has antidepressant effects. However, its underlying mechanism remains unknown.

MATERIALS AND METHODS

A chronic unpredictable mild stress (CUMS) paradigm was used as a rat model of depression. SD rats were randomly assigned to a normal control (NC) group or one exposed to a CUMS paradigm. Of the latter group, rats were assigned to four subgroups: no treatment (CUMS), fluoxetine-treated (FLU), high-dose and low-dose SSD-treated (SSDH and SSDL). SSD was orally administrated of 1.50 mg/kg and 0.75 mg/kg/days for three weeks in the SSDH and SSDL groups, respectively. Fluoxetine was administrated at a dose of 2.0 mg/kg/days. SSD's antidepressant effects were assessed using the open field test, forced swim test, and sucrose preference test. Glutamate levels were quantified by ELISA. Western blot and immunochemical analyses were conducted to quantify proteins in the Homer protein homolog 1 (Homer1)-metabotropic glutamate receptor 5 (mGluR5) and mammalian target of rapamycin (mTOR) pathways in the hippocampal CA1 region. To measure related gene expression, RT-qPCR was employed.

RESULTS

CUMS-exposed rats treated with SSD exhibited increases in food intake, body weight, and improvements in the time spent in the central are and total distance traveled in the OFT, and less pronounced pleasure-deprivation behaviors. SSD also decreased glutamate levels in CA1. In CA1 region of CUMS-exposed rats, SSD treatment increased mGluR5 expression while decreasing Homer1 expression. SSD also increased expressions of postsynaptic density protein 95 (PSD95) and synapsin I (SYP), and the ratios of p-mTOR/mTOR, p-p70S6k/p70S6k, and p-4E-BP1/4E-BP1 in the CA1 region in CUMS-exposed rats.

CONCLUSIONS

SSD treatment reduces glutamate levels in the CA1 region and promotes the expression of the synaptic proteins PSD-95 and SYP via the regulation of the Homer1-mGluR5 and downstream mTOR signaling pathways. These findings suggest that SSD could act as a natural neuroprotective agent in the prevention of depression.

Adeno-Associated Viruses for Modeling Neurological Diseases in Animals: Achievements and Prospects

Adeno-associated virus (AAV) vectors have become an attractive tool for efficient gene transfer into animal tissues. Extensively studied as the vehicles for therapeutic constructs in gene therapy, AAVs are also applied for creating animal models of human genetic disorders. Neurological disorders are challenging to model in laboratory animals by transgenesis or genome editing, at least partially due to the embryonic lethality and the timing of the disease onset. Therefore, gene transfer with AAV vectors provides a more flexible option for simulating genetic neurological disorders. Indeed, the design of the AAV expression construct allows the reproduction of various disease-causing mutations, and also drives neuron-specific expression. The natural and newly created AAV serotypes combined with various delivery routes enable differentially targeting neuronal cell types and brain areas in vivo. Moreover, the same viral vector can be used to reproduce the main features of the disorder in mice, rats, and large laboratory animals such as non-human primates. The current review demonstrates the general principles for the development and use of AAVs in modeling neurological diseases. The latest achievements in AAV-mediated modeling of the common (e.g., Alzheimer’s disease, Parkinson’s disease, ataxias, etc.) and ultra-rare disorders affecting the central nervous system are described. The use of AAVs to create multiple animal models of neurological disorders opens opportunities for studying their mechanisms, understanding the main pathological features, and testing therapeutic approaches.

Polysaccharides from Polygonatum cyrtonema Hua Reduce Depression-Like Behavior in Mice by Inhibiting Oxidative Stress-Calpain-1-NLRP3 Signaling Axis

Polysaccharides from Polygonatum cyrtonema Hua (PSP) exert antioxidant, anti-inflammatory, and antidepressant effects. Production of reactive oxygen species (ROS) and activation of the calpain system and the NOD-like receptor protein 3 (NLRP3) inflammasome are closely related to the pathogenesis of depression. However, the relationships among those pathways and the protective effects of PSP have not been characterized. In this study, lipopolysaccharide (LPS) and chronic unpredictable mild stress- (CUMS-) induced depression models were used to evaluate the protective mechanisms of PSP against depression. ROS levels were measured in HT-22 cells using flow cytometry. Brain tissues were collected to determine the levels of oxidation-related indicators and inflammatory cytokines. The protein levels of calpain-1, calpain-2, calpastatin, phosphatase and Tensin Homolog deleted on Chromosome 10 (PTEN), suprachiasmatic nucleus circadian oscillatory protein (SCOP), nuclear factor-erythroid factor 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), NLRP3, apoptosis-associated speck-like protein (ASC), caspase-1, cleaved-caspase-1, ionized calcium binding adapter molecule 1 (Iba1), phosphorylation of extracellular signal-regulated kinase (p-ERK), nuclear factor-kappa B (NF-κB), interleukin-1β (IL-1β), and glial fibrillary acidic protein (GFAP) were measured using western blotting or immunofluorescence. In cellular experiments, we showed that PSP attenuated LPS-induced production of ROS in HT-22 cells. In animal experiments, we found that LPS increased the expression of calpain-1, NLRP3, ASC, caspase-1, cleaved-caspase-1, Iba1, p-ERK, NF-κB, and GFAP and reduced the expression of calpastatin, PTEN, SCOP, and Nrf2. Administration of PSP reversed these changes. N-Acetyl-L-cysteine (NAC) administration also inhibited oxidative stress and activation of the calpain system and the NLRP3 inflammasome. Furthermore, PSP, calpeptin, MCC950 (a selective NLRP3 inflammasome inhibitor), and NAC reduced LPS-induced proinflammatory cytokine release. We also showed that PSP prevented CUMS-induced changes in the calpain system and the Nrf2 and NLRP3 signaling pathways and reduced depression-like behavior. These results indicate that PSP exerts antidepressant effects through regulation of the oxidative stress-calpain-1-NLRP3 signaling axis.

VIP alleviates sepsis-induced cognitive dysfunction as the TLR-4/NF-κB signaling pathway is inhibited in the hippocampus of rats

Cognitive dysfunction caused by sepsis-associated encephalopathy (SAE) is still poorly understood. It is reported that vasoactive intestinal peptide (VIP) exerts its anti-inflammatory effects in multiple diseases, while its biological function in SAE remains unclear. We aimed to figure out whether VIP has influence on sepsis-induced neuroinflammation and cognitive dysfunction. To induce sepsis, rats were subjected to cecal ligation and puncture (CLP) operation. Morris water maze test and fear conditioning test were conducted to reveal cognitive dysfunctions. TUNEL assay was performed to evaluate apoptosis. We found out that the expression of VIP was downregulated in the hippocampus of septic rats. VIP was verified to attenuate sepsis-induced memory impairment following CLP. Additionally, we examined apoptosis and inflammation in rats' hippocampus. It is worth noting that VIP inhibited the apoptosis in the hippocampus and reduced the productions of proinflammatory cytokines TNF-α, IL-6 and IL-1β. Furthermore, our data confirmed that VIP was involved in regulating the TLR-4/NF-κB signaling. In conclusion, VIP inhibited neuroinflammation and cognitive impairment in hippocampus of septic rats through the TLR-4/NF-κB signaling pathway.

Microglia Loss and Astrocyte Activation Cause Dynamic Changes in Hippocampal [18F]DPA-714 Uptake in Mouse Models of Depression

Major depression is a serious and chronic mental illness. However, its etiology is poorly understood. Although glial cells have been increasingly implicated in the pathogenesis of depression, the specific role of microglia and astrocytes in stress-induced depression remains unclear. Translocator protein (TSPO) has long been considered a marker of neuroinflammation and microglial activation. However, this protein is also present on astrocytes. Thus, it is necessary to explore the relationships between TSPO, microglia, and astrocytes in the context of depression. In this study, C57BL/6J male mice were subjected to chronic unpredictable stress (CUS) for 5 weeks. Subsequently, sucrose preference and tail suspension tests (TSTs) were performed to assess anhedonia and despair in these mice. [18F]DPA-714 positron emission tomography (PET) was adopted to dynamically assess the changes in glial cells before and 2, 4, or 5 weeks after CUS exposure. The numbers of TSPO+ cells, ionized calcium-binding adaptor molecule (Iba)-1+ microglial cells, TSPO+/Iba-1+ cells, glial fibrillary acidic protein (GFAP)+ astrocytes, TSPO+/GFAP+ cells, and TUNEL-stained microglia were quantified using immunofluorescence staining. Real-time PCR was used to evaluate interleukin (IL)-1β, IL-4, and IL-18 expression in the hippocampus. We observed that hippocampal [18F]DPA-714 uptake significantly increased after 2 weeks of CUS. However, the signal significantly decreased after 5 weeks of CUS. CUS significantly reduced the number of Iba-1+, TSPO+, and TSPO+/Iba-1+ cells in the hippocampus, especially in the CA1 and dentate gyrus (DG) subregions. However, this intervention increased the number of GFAP+ astrocytes in the CA2/CA3 subregions of the hippocampus. In addition, microglial apoptosis in the early stage of CUS appeared to be involved in microglia loss. Further, the expression of pro-inflammatory cytokines (IL-1β and IL-18) was significantly decreased after CUS. In contrast, the expression of the anti-inflammatory cytokine IL-4 was significantly increased after 2 weeks of CUS. These results suggested that the CUS-induced dynamic changes in hippocampal [18F]DPA-714 uptake and several cytokines may be due to combined microglial and astrocyte action. These findings provide a theoretical reference for the future clinical applications of TSPO PET.

Hippocampal Over-Expression of Cyclooxygenase-2 (COX-2) Is Associated with Susceptibility to Stress-Induced Anhedonia in Mice

The phenomenon of individual variability in susceptibility/resilience to stress and depression, in which the hippocampus plays a pivotal role, is attracting increasing attention. We investigated the potential role of hippocampal cyclooxygenase-2 (COX-2), which regulates plasticity, neuroimmune function, and stress responses that are all linked to this risk dichotomy. We used a four-week-long chronic mild stress (CMS) paradigm, in which mice could be stratified according to their susceptibility/resilience to anhedonia, a key feature of depression, to investigate hippocampal expression of COX-2, a marker of microglial activation Iba-1, and the proliferation marker Ki67. Rat exposure, social defeat, restraints, and tail suspension were used as stressors. We compared the effects of treatment with either the selective COX-2 inhibitor celecoxib (30 mg/kg/day) or citalopram (15 mg/kg/day). For the celecoxib and vehicle-treated mice, the Porsolt test was used. Anhedonic (susceptible) but not non-anhedonic (resilient) animals exhibited elevated COX-2 mRNA levels, increased numbers of COX-2 and Iba-1-positive cells in the dentate gyrus and the CA1 area, and decreased numbers of Ki67-positive cells in the subgranular zone of the hippocampus. Drug treatment decreased the percentage of anhedonic mice, normalized swimming activity, reduced behavioral despair, and improved conditioned fear memory. Hippocampal over-expression of COX-2 is associated with susceptibility to stress-induced anhedonia, and its pharmacological inhibition with celecoxib has antidepressant effects that are similar in size to those of citalopram.

Neuroprotective Efficiency of Prodigiosins Conjugated with Selenium Nanoparticles in Rats Exposed to Chronic Unpredictable Mild Stress is Mediated Through Antioxidative, Anti-Inflammatory, Anti-Apoptotic, and Neuromodulatory Activities

Purpose

Depression is a mood disorder accompanied by intensive molecular and neurochemical alterations. Currently, available antidepressant therapies are not fully effective and are often accompanied by several adverse impacts. Accordingly, the ultimate goal of this investigation was to clarify the possible antidepressant effects of prodigiosins (PDGs) loaded with selenium nanoparticles (PDGs-SeNPs) in chronic unpredictable mild stress (CUMS)-induced depression-like behavior in rats.

Methods

Sixty Sprague Dawley rats were randomly allocated into six groups: control, CUMS group (depression model), fluoxetine (Flu, 10 mg/kg)+CUMS, PDGs+CUMS (300 mg/kg), sodium selenite (Na₂SeO₃, 400 mg/kg)+CUMS, and PDGs-SeNPs+CUMS (200 mg/kg). All treatments were applied orally for 28 consecutive days.

Results

PDGs-SeNPs administration prevented oxidative insults in hippocampal tissue, as demonstrated by decreased oxidant levels (nitric oxide and malondialdehyde) and elevated innate antioxidants (glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase), in addition to the upregulated expression of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 in rats exposed to CUMS. Additionally, PDGs-SeNPs administration suppressed neuroinflammation in hippocampal tissue, as determined by the decreased production of pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1β, and interleukin-6), increased anti-inflammatory cytokine interleukin-10, and decreased inflammatory mediators (prostaglandin E2, cyclooxygenase-2, and nuclear factor kappa B). Moreover, PDGs-SeNPs administration in stressed rats inhibited neuronal loss and the development of hippocampal apoptosis through enhanced levels of B cell lymphoma 2 and decreased levels of caspase 3 and Bcl-2-associated X protein. Interestingly, PDGs-SeNPs administration improved hormonal levels typically disrupted by CUMS exposure and significantly modulated hippocampal levels of monoamines, brain-derived neurotrophic factor, monoamine oxidase, and acetylcholinesterase activities, in addition to upregulating the immunoreactivity of glial fibrillary acidic protein in CUMS model rats.

Conclusion

PDGs-SeNPs may serve as a prospective antidepressant candidate due to their potent antioxidant, anti-inflammatory, and neuroprotective potential.

Phytoestrogen genistein modulates neuron-microglia signaling in a mouse model of chronic social defeat stress

Microglia, resident immune cells in the brain, are shown to mediate the crosstalk between psychological stress and depression. Interestingly, increasing evidence indicates that sex hormones, particularly estrogen, are involved in the regulation of immune system. In this study, we aimed to understand the potential effects of chronic social defeat stress (CSDS) and genistein (GEN), an estrogenic compound of the plant origin, on neuron-microglia interactions in the mouse hippocampus. The time spent in the avoidance zone in the social interaction test was increased by CSDS 1 day after the exposure, while the avoidance behavior returned to control levels 14 days after the CSDS exposure. Similar results were obtained from the elevated plus-maze test. However, the immobility time in the forced swim test was increased by CSDS 14 days after the exposure, and the depression-related behavior was in part alleviated by GEN. The numerical densities of microglia in the hippocampus were increased by CSDS, and they were decreased by GEN. The voxel densities of synaptic structures and synaptic puncta colocalized with microglia were decreased by CSDS, and they were increased by GEN. Neither CSDS nor GEN affected the gene expressions of major pro-inflammatory cytokines. Conversely, the expression levels of genes related to neurotrophic factors were decreased by CSDS, and they were partially reversed by GEN. These findings show that GEN may in part alleviate stress-related symptoms, and the effects of GEN may be associated with the modulation of neuron-microglia signaling via chemokines and neurotrophic factors in the hippocampus.

Biology of cyclooxygenase-2: An application in depression therapeutics

Depressive Disorder is a common mood disorder or affective disorder that is dominated by depressed mood. It is characterized by a high incidence and recurrence. The onset of depression is related to genetic, biological and psychosocial factors. However, the pathogenesis is still unclear. In recent years, there has been an increasing amount of research on the inflammatory hypothesis of depression, in which cyclo-oxygen-ase 2 (COX-2), a pro-inflammatory cytokine, is closely associated with depression. A variety of chemical drugs and natural products have been found to exert therapeutic effects by modulating COX-2 levels. This paper summarizes the relationship between COX-2 and depression in terms of neuroinflammation, intestinal flora, neurotransmitters, HPA axis, mitochondrial dysfunction and hippocampal neuronal damage, which can provide a reference for further preventive control, clinical treatment and scientific research on depression.

Exercise rather than fluoxetine promotes oligodendrocyte differentiation and myelination in the hippocampus in a male mouse model of depression

Although selective serotonin reuptake inhibitor (SSRI) systems have been meaningfully linked to the clinical phenomena of mood disorders, 15-35% of patients do not respond to multiple SSRI interventions or even experience an exacerbation of their condition. As we previously showed, both running exercise and fluoxetine reversed depression-like behavior. However, whether exercise reverses depression-like behavior more quickly than fluoxetine treatment and whether this rapid effect is achieved via the promotion of oligodendrocyte differentiation and/or myelination in the hippocampus was previously unknown. Sixty male C57BL/6 J mice were used in the present study. We subjected mice with unpredictable chronic stress (UCS) to a 4-week running exercise trial (UCS + RN) or intraperitoneally injected them with fluoxetine (UCS + FLX) to address these uncertainties. At the behavioral level, mice in the UCS + RN group consumed significantly more sugar water in the sucrose preference test (SPT) at the end of the 7th week than those in the UCS group, while those in the UCS + FLX group consumed significantly more sugar water than mice in the UCS group at the end of the 8th week. The unbiased stereological results and immunofluorescence analyses revealed that running exercise, and not fluoxetine treatment, increased the numbers of CC1⁺ and CC1⁺/Olig2⁺/BrdU⁺ oligodendrocytes in the CA1 subfield in depressed mice exposed to UCS. Moreover, running exercise rather than fluoxetine increased the level of myelin basic protein (MBP) and the G-ratio of myelinated nerve fibers in the CA1 subfield in the UCS mouse model. Unlike fluoxetine, exercise promoted hippocampal myelination and oligodendrocyte differentiation and thus has potential as a therapeutic strategy to reduce depression-like behaviors induced by UCS.

Anti-Inflammatory and Anti-Oxidative Effects of AM404 in IL-1β-Stimulated SK-N-SH Neuroblastoma Cells

An emerging number of studies address the involvement of neuroinflammation and oxidative stress in the pathophysiology of central nervous system (CNS) disorders such as depression, schizophrenia, anxiety, and neurodegenerative diseases. Different cytokines and molecules, such as prostaglandin (PG) E₂, are associated with neuroinflammatory processes. The active acetaminophen metabolite AM404 has been shown to prevent inflammation and neuroinflammation in primary microglia and organotypic hippocampal slice cultures. However, its effects on pathophysiological conditions in the CNS and especially on neurons are still poorly understood. In this study, we therefore evaluated the effects of AM404 and acetaminophen on the arachidonic acid cascade and oxidative stress induced by interleukin (IL)-1β in human SK-N-SH neuronal cells. We observed that AM404 and acetaminophen significantly and concentration-dependent inhibited IL-1β-induced release of PGE₂, independent of cyclooxygenases (COX)-1 and COX-2 enzymatic activity as well as COX-2 mRNA and protein levels in SK-N-SH-cells. The reduction of IL-1β-induced PGE₂-release by AM404 and acetaminophen treatment might be mediated by the 8-iso-PGF_2α pathway since IL-1β-induced synthesis of this free radical marker is dose-dependently reduced by both compounds, respectively. Therefore, understanding of the potential therapeutic properties of AM404 in neuroinflammation and oxidative stress might lead to future treatment options of different neurological disorders.

Electroacupuncture Ameliorates Depression-Like Behaviour in Rats by Enhancing Synaptic Plasticity via the GluN2B/CaMKII/CREB Signalling Pathway

Background

Hippocampal synaptic plasticity during the pathological process of depression has received increasing attention. Hippocampal neuron atrophy and the reduction in synaptic density induced by chronic stress are important pathological mechanisms of depression. Electroacupuncture (EA) exerts beneficial effects on depression, but the mechanism is unclear. This study explored the effect of EA on synaptic plasticity and the potential mechanism.

Methods

Forty-eight SD rats were randomly divided into the control, chronic unpredictable mild stress (CUMS), EA, and fluoxetine (FLX) groups, and each group consisted of 12 rats. The sucrose preference test, open field test, and forced swimming test were used for the evaluation of depression-like behaviour, and Golgi and Nissl staining were used for the assessment of synaptic plasticity. Western blotting and immunofluorescence were conducted to detect proteins related to synaptic plasticity and to determine their effects on signalling pathways.

Results

We found that CUMS led to depression-like behaviours, including a reduced preference for sucrose, a prolonged immobility time, and reduced exploration activity. The dendritic spine densities and neuron numbers and the protein levels of MAP-2, PSD-95, and SYN were decreased in the hippocampi of rats with CUMS-induced depression, and these trends were reversed by EA. The molecular mechanism regulating this plasticity may involve the GluN2B/CaMKII/CREB signalling pathway.

Conclusion

These results suggest that EA can improve depression-like behaviour and hippocampal plasticity induced by CUMS, and the mechanism may be related to the GluN2B/CaMKII/CREB pathway.

Serum-Derived Neuronal Exosomal miRNAs as Biomarkers of Acute Severe Stress

Stress is the physical and psychological tension felt by an individual while adapting to difficult situations. Stress is known to alter the expression of stress hormones and cause neuroinflammation in the brain. In this study, miRNAs in serum-derived neuronal exosomes (nEVs) were analyzed to determine whether differentially expressed miRNAs could be used as biomarkers of acute stress. Specifically, acute severe stress was induced in Sprague-Dawley rats via electric foot-shock treatment. In this acute severe-stress model, time-dependent changes in the expression levels of stress hormones and neuroinflammation-related markers were analyzed. In addition, nEVs were isolated from the serum of control mice and stressed mice at various time points to determine when brain damage was most prominent; this was found to be 7 days after foot shock. Next-generation sequencing was performed to compare neuronal exosomal miRNA at day 7 with the neuronal exosomal miRNA of the control group. From this analysis, 13 upregulated and 11 downregulated miRNAs were detected. These results show that specific miRNAs are differentially expressed in nEVs from an acute severe-stress animal model. Thus, this study provides novel insights into potential stress-related biomarkers.

MiR-129-5p prevents depressive-like behaviors by targeting MAPK1 to suppress inflammation

Depression is a complex etiological disease with limited effective treatments. Previous studies have indicated the involvement of miRNAs in the pathophysiology of mood disorders. In this study, we focused on the role and mechanisms of miR-129-5p in depression by successfully constructing mice models of depressive-like behavior via chronic unpredictable mild stress (CUMS) exposure. Herein, miR-129-5p expression was decreased in the hippocampus of CUMS mice model. Upregulation of miR-129-5p reduced depressive-like behaviors of CUMS mice, as revealed in sucrose preference test, novelty suppressed feeding test, forced swim test, tail suspension test, social interaction test. MiR-129-5p upregulation decreased the concentrations and protein levels of proinflammatory cytokines (IL-6, IL-1β and TNF-α), indicating the inhibitory role of miR-129-5p in inflammation. Furthermore, miR-129-5p was identified to target MAPK1. MAPK1 was negatively regulated by miR-129-5p, and silencing of MAPK1 attenuated depressive-like behaviors in CUMS mice. Moreover, MAPK1 downregulation decreased inflammation in the hippocampus of CUMS mice. Upregulation of MAPK1 reversed the suppressive effects of miR-129-5p upregulation on depressive-like behaviors and inflammation in CUMS mice. In conclusion, the current study identified that miR-129-5p reduces depressive-like behaviors and suppresses inflammation by targeting MAPK1 in CUMS mice, offering a novel molecular interpretation for depression prevention.