Depression In Mice Research Articles

Olfactory stimulation with multiple odorants prevents stress-induced cognitive and psychological alterations

Abstract Acute and chronic stress markedly affects behavior by triggering sympathetic nervous system activation and several hypothalamus-pituitary-adrenal-dependent responses. Brain regions of the limbic system are responsible for the regulation of stress response, and different reports have demonstrated that their activity can be influenced by olfactory stimuli. Here we report that, in mice exposed to acute restraint stress, olfactory stimulation employing a combination of three odorants, i.e., vanillin, limonene and green odor (trans-2-hexenal and cis-3-hexenol) decreased anxiety behavior, assessed in the elevated plus maze, and halted recognition and spatial memory deficits, as appraised in two different object recognition tasks. Of note, when applied singularly, the same odorants were unable to block the detrimental effects of stress. We also found that the multiple odorants stimulation prevented the development of depressive symptoms assessed by the sucrose splash test and forced swim test in an experimental model of depression, i.e., mice exposed to a chronic unpredictable stress paradigm, and reduced interleukin 1β levels in the prefrontal cortex of depressed mice. Collectively, our data indicate that olfactory stimulation counteracts the detrimental effects of acute and chronic stress on mood regulation and cognitive functions, thus representing a potential tool for the treatment of stress-induced disorders.

Baicalin attenuates corticosterone-induced hippocampal neuronal injury by activating mitophagy in an AMPK-dependent manner

Defective mitophagy is closely related to the neuronal dysfunction and major depressive disorder (MDD). Our previous study found that baicalin could enhance nip-like protein (NIX)-mediated mitophagy and exhibit antidepressant effects, and predicted that AMPK may be the pharmacological target of baicalin. However, validated experiments are lacking. In the present study, we first demonstrated the effect of baicalin on hippocampal NIX-mediated mitophagy in CORT-induced depressive mice. Secondly, we transfected siRNA to knockdown AMPK, PGC-1α, and NIX respectively in HT22 cells, and detected the effects of baicalin on mitochondrial function, AMPK/PGC-1α/NIX pathway protein expression and mitophagy levels. Finally, AAV-shAMPKα was injected into hippocampal CA3 to knockdown AMPK in mice to validate the antidepressant effects of baicalin in vivo. The results showed that CORT induced depressive-like behaviors, accompanied with neuronal damage, mitochondrial injury, and inhibited mitophagy in the hippocampus, which were prevented by baicalin (20 mg/kg) treatment. In HT22 cells, baicalin remarkably ameliorated mitochondrial dysfunction and mitophagy disturbance induced by CORT, and these protective effects of baicalin were blocked by knockdown of AMPK, PGC-1α and NIX. Moreover, the beneficial effects of baicalin on depressive-like behaviors and NIX-mediated mitophagy were suppressed by knockdown of AMPKα in mice. Our present results further demonstrated that baicalin promotes NIX-mediated mitophagy and improves depression in an AMPK-dependent manner.

Fructus Arctii Mitigates Depressive Disorder via the Let-7e-Modulated Toll-Like Receptor (TLR) Signaling Pathway.

Depressive disorder is a common and serious public health challenge globally. Fructus arctii is a traditional medicinal plant ingredient with diverse pharmacological effects. This study aimed to investigate the therapeutic potential of Fructus arctii in alleviating depressive-like behaviors. We established a chronic unpredictable mild stress (CUMS)-induced depression mouse model to assess the antidepressant effects of Fructus arctii. BV2 cells treated with lipopolysaccharide (LPS) were used to mimic neuronal damage. Behavioral tests, including the sucrose preference test, tail-suspension test, and forced swim test, were conducted to evaluate the impact of Fructus arctii on depressive-like behaviors. Let-7e expression was detected by RT-qPCR, and TLR4 signaling pathway activation was evaluated by western blot analysis, which also assessed the inflammatory response by measuring levels of IL-6, IL-1β, MCP-1, TNF-α, and iNOS. Immunohistological analysis was conducted to detect the expression of microglia markers. Luciferase reporter assays verified the interaction between let-7e and TLR4. Fructus arctii administration effectively alleviated depressive-like behaviors induced by CUMS in mice, as evidenced by improved sucrose preference and reduced immobility time in behavioral tests. Mechanistically, Fructus arctii reversed the CUMS-induced downregulation of let-7e and upregulation of TLR4 and MyD88 protein levels in mice hippocampus tissues. In addition, Fructus arctii suppressed microglial activation and reduced the levels of inflammatory factors by upregulating let-7e. Let-7e was verified to bind to TLR4, thereby negatively regulating its expression. TLR4 overexpression reversed the suppressive effect of let-7e upregulation on inflammatory reactions and microglial activation. Furthermore, intracerebroventricular injection of let-7e agomiR alleviated depressive-like behavior and inhibited microglial activation in vivo. In summary, Fructus arctii mitigates depression by regulating the let-7e/TLR4/MyD88 pathway, offering new insights into potential depression therapies.

Hypoxanthine Produces Rapid Antidepressant Effects by Suppressing Inflammation in Serum and Hippocampus.

The occurrence and development of depression are closely related to disorders of the brain and peripheral substances. Abnormal metabolites in the blood affect the signal regulation function of the nerve center, which is one of the key factors for depression episodes. This study was focused on metabolites in serum and the mechanism of its antidepressant in the hippocampus. In the present study, serum metabolites in patients with depression were screened by metabolomic techniques. Various depressive mouse models and behavioral tests were used to assess its antidepressant effects. The expressions of inflammatory signaling were detected by using Western blot, ELISA, and immunofluorescence. We found that the metabolite hypoxanthine in the serum of patients with depression was significantly reduced, and the same result was also found in two mouse models of depression such as chronic unpredictable mild stress (CUMS) and social defeat stress (SD). By administering different doses of hypoxanthine (5, 10, 15 mg/kg), we found that only 15 mg/kg was able to significantly reduce the latency and increase food consumption in the novelty suppressed-feeding test (NSF), which was also able to reverse the depressive phenotypes of mice in the CUMS model after a single administration at 2 h later. Hypoxanthine obviously reduced the expressions of inflammation in serum and downregulated the expressions of MAPK and NLRP3-related pathways in the hippocampus in CUMS mice. Moreover, hypoxanthine also suppressed the activations of glial cells including GFAP and IBA-1 in hippocampal CA1, CA3, and dentate gyrus (DG). To sum up, hypoxanthine exerted antidepressant effect relying on the inhibition of peripheral and hippocampal inflammations by regulating MAPK, NLRP3-related pathways, and glial cells. This was the first time that we have found a disordered metabolite in patients with depression and further systematically demonstrated its efficacy and potential mechanism of antidepressants, providing new ideas for antidepressant drug development.

Limosilactobacillus-related 3-OMDP as a potential therapeutic target for depression

Objective Gut microbiota was closely involved in the pathogenesis of depression, but the underlying molecular mechanisms in depression remained unclear. This study was conducted to investigate the relationship between neurotransmitters/inflammatory factors and gut microbiota in depressed mice. Materials and methods A chronic social defeat stress (CSDS) depression model was established. Gut microbial composition was detected in faeces, neurotransmitters were detected in faeces, colon, blood and hippocampus, and inflammatory factors were detected in hippocampus. After a key neurotransmitter was identified, intervention experiment was conducted to explore whether it could improve depressive-like behaviours. Results Six differential genera in faeces, 14 differential neurotransmitters in gut-brain axis, and two differential inflammatory factors (interleukin-1 beta (IL-1β) and interleukin-6 (IL-6)) in hippocampus were identified in depressed mice. There were significant correlations among differential genera, differential neurotransmitters and IL-1β/IL-6. Among these differential neurotransmitters, 3-O-Methyldopa (3-OMDP) was found to be consistently decreased in faeces, colon, blood and hippocampus, and 3-OMDP was significantly correlated to Limosilactobacillus and IL-1β. After receiving 3-OMDP, the depressive-like behaviours in depressed mice were improved and the increased IL-1β/IL-6 levels were reversed. Conclusions These results indicated that gut microbiota might affect host’s inflammation levels in brain through regulating neurotransmitters, eventually leading to the onset of depression. ‘Limosilactobacillus-3-OMDP-IL-1β/IL-6’ might be a potential pathway in the crosstalk of gut and brain, and 3-OMDP held the promise as a therapeutic target for depression.

Inhalation of H2/O2 (66.7 %/33.3 %) mitigates depression-like behaviors in diabetes mellitus complicated with depression mice via suppressing inflammation and preventing hippocampal damage

Diabetes mellitus complicated with depression (DD) is a prevalent psychosomatic disorder. It is characterized by severe cognitive impairment, and associated with high rates of disability and mortality. Although conventional treatment options are available, the efficacy of these regimens in managing DD remains limited. Molecular hydrogen (H2), a selective hydroxyl radical scavenger, has shown therapeutic potential in the treatment of various systemic diseases. This study aims to investigate the therapeutic effects of H2 on DD. A DD mouse model was established through intraperitoneal injection of streptozotocin (STZ, 150 mg/kg) and lipopolysaccharide (LPS, 0.5 mg/kg). Following the induction of DD, the mice were treated with H2/O2 (66.7 %/33.3 %)inhalation for 7 days. Behavioral assessments were conducted by standard behavioral tests, and the levels of inflammatory cytokines in peripheral blood serum and hippocampal tissue were measured using enzyme-linked immunosorbent assay (ELISA). Furthermore, magnetic resonance imaging (MRI) scans and immunofluorescence staining of the hippocampus were performed to evaluate hippocampal structural integrity. The results demonstrated that inhalation of H2/O2 (66.7 %/33.3 %) significantly ameliorated depressive behaviors and symptoms in DD mice, reversed hippocampal volume reduction, decreased inflammatory cytokine levels in peripheral blood serum and hippocampal tissue, and inhibited the activation of A1 astrocytes in the hippocampus. Our study suggests that H2/O2 (66.7 %/33.3 %) inhalation therapy may offer a promising treatment strategy for DD and its associated symptoms.

Breakdown of the blood-brain barrier in depressed mice induced by chronic unpredictable mild stress

BackgroundRecent studies have suggested potential impairment of the blood-brain barrier (BBB) in depression. However, due to the limited research and variability in animal models, further investigation using diverse and stable models is necessary. MethodsA male mouse model of depression was established using the chronic unpredictable mild stress (CUMS) protocol. Following model establishment, depression-like behaviors were assessed using the sucrose preference test, tail suspension test, and forced swimming test. Morphological changes in the hippocampus were examined through hematoxylin-eosin staining. BBB permeability was evaluated using the Evans blue leakage test, fluorescein sodium (NaF) leakage test, and serum S100B content assessment. Gene and protein expression levels of BBB-related proteins in the hippocampus were determined via real-time PCR, western blotting, and immunofluorescence assays. ResultsCUMS exposure induced depression-like behaviors, including reduced body weight gain, diminished sucrose preference, and prolonged immobility in both the tail suspension test and forced swimming test. While no significant pathological changes were observed in the hippocampus of either group, increased BBB permeability was noted in the CUMS group, as evidenced by enhanced NaF leakage into the brain parenchyma and elevated serum S100B levels. Gene expression analysis revealed downregulation of angiogenesis-related genes and tight junction proteins in the CUMS group. Additionally, protein levels of tight junction proteins Claudin-5 and ZO-1 were lower in the CUMS group compared to controls. LimitationsThis study is limited to a male mouse model, and the BBB in females is worth exploring in the future. ConclusionsIncreased BBB permeability and decreased expression of tight junction proteins Claudin5 and ZO-1 were observed in mice with CUMS-induced depression.

Development and Validation of a Comprehensive Prognostic and Depression Risk Index for Gastric Adenocarcinoma

Depressive disorder contributes to the initiation and prognosis of patients with cancer, but the interaction between cancer and depressive disorder remains unclear. We generated a gastric adenocarcinoma patient-derived xenograft mice model, treated with chronic unpredictable mild stimulation. Based on the RNA-sequence from the mouse model, patient data from TCGA, and MDD-related (major depressive disorder) genes from the GEO database, 56 hub genes were identified by the intersection of differential expression genes from the three datasets. Molecular subtypes and a prognostic signature were generated based on the 56 genes. A depressive mouse model was constructed to test the key changes in the signatures. The signature was constructed based on the NDUFA4L2, ANKRD45, and AQP3 genes. Patients with high risk-score had a worse overall survival than the patients with low scores, consistent with the results from the two GEO cohorts. The comprehensive results showed that a higher risk-score was correlated with higher levels of tumor immune exclusion, higher infiltration of M0 macrophages, M2 macrophages, and neutrophils, higher angiogenetic activities, and more enriched epithelial–mesenchymal transition signaling pathways. A higher risk score was correlated to a higher MDD score, elevated MDD-related cytokines, and the dysfunction of neurogenesis-related genes, and parts of these changes showed similar trends in the animal model. With the Genomics of Drug Sensitivity in Cancer database, we found that the gastric adenocarcinoma patients with high risk-score may be sensitive to Pazopanib, XMD8.85, Midostaurin, HG.6.64.1, Elesclomol, Linifanib, AP.24534, Roscovitine, Cytarabine, and Axitinib. The gene signature consisting of the NDUFA4L2, ANKRD45, and AQP3 genes is a promising biomarker to distinguish the prognosis, the molecular and immune characteristics, the depressive risk, and the therapy candidates for gastric adenocarcinoma patients.

12218 Gnrh Pulse Frequency And Irregularity Play A Role In Depression

Abstract Disclosure: J. Choi: None. M. Kim: None. Gonadotropin-releasing hormone (GnRH) has a role in hypothalamic control of depression, but the underlying patterns and relationship with downstream reproductive hormones are still unclear. Here we report that hypothalamic GnRH pulse frequency and irregularity increase before GnRH pulse amplitude slowly decreases during social defeated stress models (SDS). While mice castrated and testosterone inhibited induced depression by conducting SDS, these mice led to anti-depression effects and affected by GnRH signaling, indicating that high-frequency GnRH pulses. Regramming the endogenous GnRH pulses of depressed male mice via an optogenetic approach revealed that increasing GnRH pulses frequency causes depression acceleration, while lowering the frequency of and stabilizing GnRH pulses can slow down depression. In conclusion, GnRH pulses are important for depression in male mice. Presentation: 6/1/2024

Electroacupuncture attenuates depressive-like behaviors in poststroke depression mice through promoting hippocampal neurogenesis and inhibiting TLR4/NF-κB/NLRP3 signaling pathway.

The aim of this study was to investigate the impact and underlying molecular mechanisms of electroacupuncture on mice with poststroke depression (PSD). Mice were randomly allocated into sham, PSD, and electroacupuncture groups. Mice in the PSD and electroacupuncture groups underwent middle cerebral artery occlusion (MCAO) surgery following with sedentary behavior. Electroacupuncture targeting Zusanli (ST36) acupoint was performed 24 h after MCAO for 4 weeks in electroacupuncture group. The sucrose preference test, forced swimming test, open field test, tail suspension test, elevated plus maze, Catwalk analysis, RNA sequencing, Nissl staining, Golgi staining, TUNEL staining, Edu labeling, and doublecortin staining were performed. Lymphocyte subsets in peripheral blood and the levels of IL-1β, IL-6, TNF-α, and expression of Iba1/CD86, Iba1/NLRP3, TLR4/p38/NF-κB/NLRP3 pathways in the hippocampus were detected. Electroacupuncture effectively protected against the development of depression-like symptoms. The number of granulosa cells and doublecortin-positive cells in the dentate gyrus (DG) were significantly decreased in PSD group, which were significantly upregulated ( P < 0.01) by electroacupuncture. Electroacupuncture also significantly reduced ( P < 0.05) TUNEL-positive cells in the DG and CA1. RNA-seq revealed that electroacupuncture may exert antidepressant effect by regulating the inflammation mediated by TLR4/NF-κB/NLRP3 pathway in hippocampus. Electroacupuncture remarkably elevated ( P < 0.01) the ratio of CD4+ to CD8+ T cells and percentage of CD3-CD49b+ cells in CD45+CD49b+ cells in the peripheral blood. Electroacupuncture significantly reduced ( P < 0.05) the high levels of IL-1β, IL-6, TNF-α, iba1, TLR4, p-p38, p-NF-κB, and NLRP3 and sedentary behavior. Electroacupuncture was observed to mitigate depression symptoms and increase hippocampal neurogenesis in mice with PSD, possibly by inhibiting TLR4/p38/NF-κB/NLRP3 pathways and improving the microglia-mediated inflammatory microenvironment in the hippocampus.

Contagion of depression: a double-edged sword

Depression is a significant mental health issue with extensive economic implications, and recent studies suggest it may be transmitted between individuals. However, the mechanisms of this contagion remain unclear, and the social buffering effect has been understudied. This research employs three rodent models, including stress crossover, cohabitation-induced, and non-contact induced depression contagion models, to explore these mechanisms. Here, we report that that naive mice cohabiting with depressed mice showed increased corticosterone levels and depressive behaviors, unlike those with stressed mice, who did not exhibit these changes and even mitigated desperation in stressed mice. Non-contact cohabitation did not produce significant behavioral differences, but exposure to bedding from depressed mice reduced sucrose preference in naive mice. This study introduces reliable models of depression contagion, suggesting it operates independently of stress transmission. The interplay between depression contagion and social buffering may vary in different contexts. These findings provide new insights into the mechanisms of depression contagion and potential strategies for preventing depressive disorders.

Salidroside exerts antidepressant-like action by promoting adult hippocampal neurogenesis through SIRT1/PGC-1α signalling.

Depression is one of the major mental disorders, which seriously endangers human health, brings a serious burden to patients’ families. In this study, we intended to further explore the antidepressant-like effect and possible molecular mechanisms of Salidroside (SAL). We built corticosterone (CORT)-induced depressive mice model and used behavioural tests to evaluate depression behaviour. To explore the molecular mechanisms of SAL, we employed a variety of methods such as immunofluorescence, western blot, pharmacological interference, etc. The results demonstrated that SAL both at 25 mg/kg and 50 mg/kg can reduce immobility time in the tail suspension test (TST). At the same time, SAL treatment could restore the reduced sugar water intake preference in the sucrose preference test (SPT) in CORT-induced depressive mice and reduce the immobility time in TST and forced swimming experiments (FST). In addition, SAL treatment reversed the reduction in the number of Ki-67, BrdU, and NeuN in the hippocampus due to CORT treatment. SAL treatment also restored the expression of SIRT1, PGC-1α, brain-derived neurotrophic factor (BDNF) and other proteins in the hippocampus. In addition, after blocking SIRT1 signalling with EX527, we found that the treatment with SAL failed to reduce the immobility time in TST and FST, the level of SIRT1 and PGC-1α activity were correspondingly downregulated, and the expression of DCX and Ki-67 in the hippocampus failed to be activated. These findings suggested that SAL exerts antidepressant-like effects by promoting hippocampal neurogenesis through the SIRT1/PGC-1α signalling pathway.

Tofacitinib prevents depressive-like behaviors through decreased hippocampal microgliosis and increased BDNF levels in both LPS-induced and CSDS-induced mice.

Depressive disorders are a global mental health challenge that is closely linked to inflammation, especially in the post-COVID-19 era. The JAK-STAT pathway, which is primarily associated with inflammatory responses, is not fully characterized in the context of depressive disorders. Recently, a phase 3 retrospective cohort analysis heightened that the marketed JAK inhibitor tofacitinib is beyond immune diseases and has potential for preventing mood disorders. Inspired by these clinical facts, we investigated the role of the JAK-STAT signaling pathway in depression and comprehensively assessed the antidepressant effect of tofacitinib. We found that aberrant activation of the JAK-STAT pathway is highly conserved in the hippocampus of classical depressive mouse models: LPS-induced and chronic social defeat stress (CSDS)-induced depressive mice. Mechanistically, the JAK-STAT pathway mediates proinflammatory cytokine production and microgliosis, leading to synaptic defects in the hippocampus of both depressive models. Remarkably, the JAK inhibitor tofacitinib effectively reverses these phenomena, contributing to its antidepressant effect. These findings indicate that the JAK/STAT pathway could be implicated in depressive disorders, and suggest that the JAK inhibitor tofacitinib has a potential translational implication for preventing mood disorders far beyond its current indications.

Glutamate chemical exchange saturation transfer (GluCEST) MRI to evaluate the relationship between demyelination and glutamate content in depressed mice

Glutamatergic alteration is one of the potential mechanisms of depression. However, there is no consensus on whether glutamate metabolism changes affect the myelin structure of depression in mouse models. Glutamate chemical exchange saturation transfer (GluCEST) is a novel and powerful molecular imaging technique that can visualize glutamate distribution. In this study, we used the GluCEST imaging technique to look at glutamate levels in mice under chronic unpredictable mild stress (CUMS) and how they relate to demyelination. The CUMS mice were exposed to different stress factors for 6 weeks. Evaluated of depression in CUMS mice by behavioral tests. MRI scans were then performed, including T2-mapping, GluCEST, and diffusion tensor imaging (DTI) sequences. Brain tissues were collected for Luxol Fast Blue staining and immunofluorescence staining to analyze the changes in the myelin sheath. Artificially sketched regions of interest (ROI) (corpus callosum, hippocampus, and thalamus) were used to calculate the GluCEST value, fractional anisotropy (FA), and T2 value. Compared with the control group, the GluCEST value in the ROIs of CUMS mice significantly decreased. Similarly, the FA value in ROIs was lower in the CUMS group than in the CTRL group, but the T2 value did not differ significantly between the two groups. The histological results showed that ROIs in the CUMS group had demyelination compared with the CTRL group, indicating that DTI was more sensitive than T2 mapping in detecting myelin abnormalities. Furthermore, the GluCEST value in the ROIs correlates positively with the FA value. These findings suggest that altered glutamate metabolism may be one of the important factors leading to demyelination in depression, and GluCEST is expected to serve as an imaging biological marker for the diagnosis of demyelination in depression.

Depression exacerbates myocardial ischemia-reperfusion injury in mice via CNR2 gene and MIF-AMPK signaling pathway

BackgroundMyocardial ischemia-reperfusion(I/R)injury constitute the fundamental pathophysiology of acute myocardial infarction (AMI). Ischemic heart releases macrophage migration inhibitory factor (MIF), which activates MIF- AMPK signaling pathway. Depression is a significant risk factor for AMI. In a state of depression, peripheral expression of cannabinoid receptor 2 (CNR2) genes was downregulated. AimsWe investigated the mechanism by which depression exacerbates myocardial I/R injury through the CNR2 and MIF-AMPK signaling pathways. MethodsWe established mouse models of depression and myocardial I/R. Left ventricular function was assessed using cardiac ultrasound and TTC staining. The protein levels of myocardial CNR2, MIF, AMPK, and ACC were determined by Western blot, while the expression level of CNR2 was measured using RT-qPCR. Additionally, MIF content in peripheral blood was quantified using ELISA. ResultsAfter I/R, the expression level of CNR2 was found to be lower in the depression group, leading to a deterioration in left heart function. Depressed mice exhibited lower secretion of MIF, accompanied by a decrease in the activation of the MIF-AMPK signaling pathway. However, injection of CNR2 agonist JWH133 prior to ischemia increased the activation of the MIF-AMPK signaling pathway, while CNR2 inhibitor AM630 decreased the activation. LimitationsFurther research is needed to investigate the specific neuroendocrine mechanism affecting myocardial CNR2 expression in depression. And these experimental conclusions require further verification at the cellular level. ConclusionsThe activation of CNR2 in myocardium following I/R is impeded by depression, thereby exacerbating myocardial I/R injury through attenuation of the MIF-AMPK signaling pathway activation.

Genipin 1-O-β-D-gentiobioside ameliorates CUMS-induced prefrontal cortex neuron neuronal apoptosis by modulating HIPK2 SUMOylation

BackgroundDepression is a common mental illness with more than 280 million sufferers worldwide. Inflammation, particularly the c-Jun amino-terminal kinase (JNK) pathway, contributes to depression development and neuronal apoptosis. Gardenia is a herb with therapeutic effects on depression that has been shown to inhibit neuronal apoptosis. However, one of the components in gardenia, Genipin 1-O-β-D-gentiobioside(GG), has been less studied for its mechanism on depression. Thus, in the current study, we investigate how Genipin 1-O-β-D-gentiobioside improves depression and elucidate its possible mechanism of action. MethodsIn this investigation, we utilize a chronic unpredictable mild stress (CUMS) mouse model and corticosterone-induced primary cortical neurons to examine the role of GG in ameliorating depressive symptoms and neuronal apoptosis. TUNEL staining and flow cytometry assessed the effects of GG on neuronal apoptosis. Western Blot analyses and immunofluorescence assays apoptosis-related proteins in the prefrontal cortex and primary neurons. The site of action of GG in regulating homeodomain interacting protein kinase 2 (HIPK2) SUMOylation was further explored in primary neurons. We constructed siRNA-SUMO1 vectors to transfect primary neuronal cells with intracellular SUMO1 knockdown. Proximity ligation assay (PLA) experiments were performed on primary neurons according to the instructions of the assay kit to observe the physical relationship between HIPK2 and SUMO1. We predicted the HIPK2 SUMOylation modification site by an online database and constructed vectors to target and site-directed mutagenesis, then to transfected primary neuronal cells. ResultsThe results showed that GG effectively alleviated depressive-like behaviours, down-regulated apoptosis-related proteins (p-JNK, Bax, Cleaved-Caspase-3), and inhibited neuronal apoptosis in CUMS-induced depressed mice and corticosterone-induced primary cortical neurons. We reveal a complex mechanism underlying the link between GG, SUMOylation of HIPK2, and complex pathways of neuronal apoptosis regulation. K326 and K1189 are the key SUMOylation sites regulated by GG in intricate interactions of apoptosis-related proteins. ConclusionOur study demonstrated that GG exerts antidepressant-like actions through neuroprotective effects by inhibiting the apoptosis of prefrontal cortex neurons, revealing the mechanism of GG inhibition of JNK phosphorylation by enhancing HIPK2 SUMOylation.

Astrocyte-derived dominance winning reverses chronic stress-induced depressive behaviors

Individuals with low social status are at heightened risk of major depressive disorder (MDD), and MDD also influences social status. While the interrelationship between MDD and social status is well-defined, the behavioral causality between these two phenotypes remains unexplored. Here, we investigated the behavioral relationships between depressive and dominance behaviors in male mice exposed to chronic restraint stress and the role of medial prefrontal cortex (mPFC) astrocytes in these behaviors. Chronic restraint stress induced both depressive and submissive behaviors. Chemogenetic mPFC astrocyte activation significantly enhanced dominance in chronic stress-induced submissive mice by increasing the persistence of defensive behavior, although it did not affect depressive behaviors. Notably, repetitive winning experiences following mPFC astrocyte stimulation exerted anti-depressive effects in chronic restraint stress-induced depressive mice. These data indicate that mPFC astrocyte-derived winning experience renders anti-depressive effects, and may offer a new strategy for treating depression caused by low status in social hierarchies by targeting mPFC astrocytes.

Ginsenoside Re Prevents Depression-like Behaviors via Inhibition of Inflammation, Oxidative Stress, and Activating BDNF/TrkB/ERK/CREB Signaling: An In Vivo and In Vitro Study.

Depression is a widespread disease, with high mortality and recurrence rates. Recent studies have shown that elevated cytokine levels are implicated in the molecular mechanisms of depression. Oxidative stress contributes to the stimulation of cytokine production. Growing evidence suggests that ginsenoside Re (Gs-Re) exerts a neuroprotective effect on the hippocampus by suppressing oxidative stress and inflammation. However, the effect and mechanism of Gs-Re in the treatment of depression remain understudied. This study aimed to evaluate the neuroprotective and antidepressant-like effects of Gs-Re and the possible underlying mechanisms. In this article, the antidepressant-like effect of the Gs-Re was studied both in vitro (H2O2-induced oxidative stress in HT-22 cells) and in vivo (reserpine-induced depressive model mice). Our results indicated that, at the cellular level, Gs-Re effectively enhanced cell survival following H2O2 stimulation, inhibited the mass production of oxidative stress markers (MDA and ROS), and prevented the occurrence of apoptosis. Moreover, Gs-Re significantly reduced the levels of proinflammatory cytokines IL-1β, IL-6, and TNF-α and restored the abnormal mitochondrial membrane potential. Subsequently, Gs-Re treatment reversed reserpine-induced neuroinflammation and depressive-like behaviors in vivo and inhibited microglia overactivation. Furthermore, the alterations in the BDNF/TrkB/ERK/CREB signaling pathway induced by H2O2 or reserpine in HT-22 cells or in the mouse hippocampus were significantly reversed by Gs-Re. K252a blocked the improvement of Gs-Re on depression-like behavior and eliminated the inhibition of oxidative stress and neuroinflammation in vivo. This study suggested that Gs-Re produces neuroprotective and depressive effects by inhibiting oxidative stress and inflammation and activating the BDNF/TrkB/ERK/CREB pathway.

Ethyl acetate extract of Nymphaea candida Presl: A potential anti-depressant and neuroprotective treatment strategy

Nymphaea candida Presl (NC), traditionally used in medicine for heat syndrome-related ailments, possesses antioxidative, anti-inflammatory, hepatoprotective, and neuroprotective properties. This research investigates the antidepressant and neuroprotective effects and mechanisms of Nymphaea candida Presl ethyl acetate (NCEA). Primary components of NCEA were identified as phenolic acids and flavonoids through UPLC-MS/MS analysis. The depression mouse model was induced via intracerebroventricular injection of Lipopolysaccharide (LPS), followed by oral administration of fluoxetine and NCEA for one week. Biochemical assays and HE staining confirmed NCEA's non-toxicity and protective effects on the liver and lungs. NCEA administration mitigated LPS-induced depressive behaviors, decreased IL-1β, TNF-α levels in the hippocampus, suppressed microglial activation, reduced Iba-1 expression, and increased NA, brain-derived neurotrophic factor (BDNF), and dendritic spine density in the hippocampus. Furthermore, NCEA enhanced cell viability in a CORT-induced PC12 cell model, decreased lactate dehydrogenase (LDH) release rate, total superoxide dismutase (SOD) inhibition rate, intracellular nitric oxide (NO) release, and reduced reactive oxygen species (ROS) production. Our research findings suggest that NCEA exhibits significant antidepressant effects, which may be attributed to its reduction of neuroinflammation, improvement in neurotransmitter levels, neuronal protection, and antioxidative stress properties.

CircKat6b Mediates the Antidepressant Effect of Esketamine by Regulating Astrocyte Function.

The abundant expression of circular RNAs (circRNAs) in the central nervous system and their contribution to the pathogenesis of depression suggest that circRNAs are promising therapeutic targets for depression. This study explored the role and mechanism of circKat6b in esketamine's antidepressant effect. We found that intravenous administration of esketamine (5mg/kg) treatment decreased the circKat6b expression in the astrocytes of hippocampus induced by a chronic unpredictable mild stress (CUMS) mouse model, while the overexpression of circKat6b in the hippocampus significantly attenuated the antidepressant effects of esketamine in depressed mice. RNA-sequencing, RT-PCR, and western blot experiments showed that the stat1 and p-stat1 expression were significantly upregulated in mouse astrocytes overexpressing circKat6b. In the CUMS mouse model, overexpression of circKat6b in the hippocampus significantly reversed the downregulation of p-stat1 protein expression caused by esketamine. Our findings demonstrated that a novel mechanism of the antidepressant like effect of esketamine may be achieved by reducing the expression of circKat6b in the astrocyte of the hippocampus of depressed mice.