Chronic Unpredictable Mild Stress Rats Research Articles

The Effect of Psilocybe cubensis on Spatial Memory and BDNF Expression in Male Rats Exposed to Chronic Unpredictable Mild Stress

ABSTRACT Psilocybin-containing mushrooms, commonly known as magic mushrooms, drastically affect mental processing, cognitive functioning, and the mood state. In the present study, we investigated the effect of the Psilocybe cubensis extract on spatial memory and the brain-derived neurotrophic factor (BDNF) in rats exposed to chronic unpredictable mild stress (CUMS). The duration of CUMS was 4 weeks. Spatial learning and memory were measured using the Morris water maze apparatus. The Psilocybe cubensis extract was intraperitoneally injected (20 mg/kg) in different time periods: 5 min before training, 24 h before training, 48 h before training, 5 min after training, and 5 min before the probe test. Results showed that CUMS impaired spatial learning and memory, and decreased BDNF in the hippocampus. Psilocybe cubensis (24 and 48 h before training) restored spatial learning, while (48 h before training) restored spatial memory impairment in CUMS rats. Psilocybe cubensis (24 and 48 h before training) increased BDNF in CUMS rats. Psilocybe cubensis administrations (expect 48 h before training) impaired spatial learning and memory and decreased BDNF levels in controls. In conclusion, we suggested that Psilocybe cubensis may be beneficial for the improvement of memory deficits induced by CUMS, while the time of injection seems to be an important factor in its final effect.

Effect of acupuncture on AMPK/ULK1 signaling pathway of hippocampus in chronic stress-induced depression rats

To observe the effect of manual acupuncture stimulation on changes of behavior and hippocampal signaling pathways of AMP-activated kinase (AMPK)/UNC-51-like kinase 1 (ULK1) in rats with chronic unpredictable mild stress (CUMS)-induced depression, so as to explore its molecular mechanism underlying improvement of depression. Thirty-two male SD rats were randomly divided into normal control, model, acupuncture and medication (fluoxetine) groups, with 8 rats in each group. The depression model was established by using CUMS (fasting, water depredation, restraint, swimming in cold water, crowding, stroboscope stimulation, and tail clipping, each of which was used once a week) for 6 weeks. Manual acupuncture stimulation was applied to "Baihui"(GV20) and "Yintang"(EX-HN3) for 10 min, once daily, 6 times a week for 6 weeks before every-day modeling. Rats of the medication group received gavage of fluoxetine (10 mg/kg) once a day for 6 weeks before every-day modeling. The percentage of sucrose preference, and the percentages of open arm times and open arm time in the elevated plus maze experiments were detected. The expression levels of AMPK, phosphorylated (p)-AMPK, ULK1, p-ULK1, mammalian target of rapamycin (mTOR) and p-mTOR proteins in the hippocampus tissue were detected by Western blot, and the expression of autophagy effecting protein (Beclin-1) and the selective autophagy receptors (p62) mRNA in the hippocampal tissue was detected using real-time fluorescence quantitative PCR, respectively. Compared with the normal group, the percentage of sucrose preference, percentage of times of entering the open arm and percentage of open arm time, the expression levels of p-AMPK /AMPK ratio, p-ULK1 /ULK1 ratio of proteins, and Beclin-1 mRNA were significantly decreased (P<0.01, P<0.05), and the expression levels of p-mTOR /mTOR ratio and p62 mRNA were significantly increased (P<0.01, P<0.05) in the model group. In comparison with the model group, the percentage of sucrose preference, percentage of open arm times and open arm time, the expression levels of p-AMPK /AMPK ratio, p-ULK1/ULK1 ratio of proteins, and Beclin-1 mRNA were significantly increased in both acupuncture and medication groups (P<0.01, P<0.05), while the expression levels of p-mTOR /mTOR ratio of proteins, and p62 mRNA were markedly decreased only in the medication group (P<0.05). Acupuncture treatment can alleviate depression-like behavior in CUMS rats, which may be related to its functions in up-regulating AMPK/ULK1 signaling pathway to induce cellular autophagy in the hippocampus.

New insights into individual differences in response to chronic unpredictable mild stress (CUMS) in rats with respect to hippocampal BDNF and GSK3-β expression levels

Preclinical and clinical studies have shown a wide-range of individual differences in response to stressors or novel environments which can affect the susceptibility to develop abnormal behaviors and neuropsychiatric disorders. Both vulnerability and resiliency have been observed in animals and humans experiencing stressful events. Chronic unpredictable mild stress (CUMS) is a rodent depression model consisting of various stressors. This protocol leads to depressive- and anhedonic-like behaviors in rodents. The present study aimed to evaluate potential individual differences in response to CUMS in rats, with respect to the expression level of brain-derived neurotrophic factor (BDNF) and glycogen synthase kinases 3-beta (GSK3-β) (proteins involved in the modulation of mood, neuroplasticity, and cognition) in the hippocampus. CUMS was performed for four consecutive weeks. Depressive-like behavior, locomotor activity, anxiety-like behavior, and pain threshold were also evaluated using forced swim test (FST), open field test (OFT), and the hot plate (HP), respectively. Real-time PCR was used to evaluate BDNF and GSK3-β expression levels. The results showed that CUMS rats can be classified as two clusters: affected and non-affected (depressed and non-depressed). Affected rats showed depressive- and anxiety-like behaviors, decreased locomotor activity, and increased pain threshold. However, non-affected rats were similar to controls. In addition, there was a downregulation of BDNF and upregulation of GSK3-β in affected rats. Spearman correlation analysis also showed a relationship between BDNF and GSK3-β expression levels with individual differences. In conclusion, the present study showed that BDNF and GSK3-β may be involved in individual differences in CUMS rats.

Jujuboside A Regulates Calcium Homeostasis and Structural Plasticity to Alleviate Depression-Like Behavior via Shh Signaling in Immature Neurons.

Depression, a leading cause of disability worldwide, is characterized by dysfunction of immature neurons, resulting in dysregulated calcium homeostasis and impaired structural plasticity. Jujuboside A (JuA), a biologically active compound derived from Semen Ziziphi Spinosae, has demonstrated anti-anxiety and anti-insomnia properties. Recent studies suggest that JuA may be a promising antidepressant, but its underlying mechanisms remain unclear. Sprague-Dawley rats were subjected to chronic unpredictable mild stress (CUMS) to induce a depression model. JuA (12.5 mg/kg, 25 mg/kg, 50 mg/kg) was administered orally for 4weeks. Emotional and cognitive function were assessed. Monoamine neurotransmitter levels were measured using enzyme-linked immunosorbent assay (ELISA). The number of immature neurons and calcium homeostasis were evaluated by immunofluorescence. Western blotting and immunofluorescence were employed to detect the expression of Sonic hedgehog (Shh) signaling proteins. Additionally, lentiviral vector expressing Shh shRNA (LV-Shh-RNAi) were infused intracerebrally to investigate the role of Shh in JuA's antidepressant effects. JuA significantly ameliorated depressive-like behavior and cognitive dysfunction in CUMS rats, increased monoamine neurotransmitter levels in serum and hippocampal tissue, reduced the number of BrdU/DCX (bromodeoxyuridine/doublecortin)-positive immature neurons, and attenuated calcium ion (Ca2+) concentration and Ca2+/calmodulin-dependent protein kinase II (CaMKII) levels in immature neurons. JuA also markedly elevated synaptic density and prominence complexity, upregulated Shh, Gli family zinc finger 1 and 2 (Gli1/2), synaptophysin (Syn) and postsynaptic density protein-95 (PSD-95) expression in the ventral dentate gyrus (vDG). However, knockdown of Shh in the vDG counteracted JuA's therapeutic effects. These findings collectively suggest that JuA improves depressive-like behavior in CUMS rats by modulating calcium homeostasis and synaptic structural plasticity in immature neurons through the Shh signaling pathway.

Low polarity fraction of Radix Bupleuri alleviates chronic unpredictable mild stress-induced depression in rats through FXR modulating bile acid homeostasis in liver, gut, and brain

Radix Bupleuri (BR, Bupleurum chinense DC.) is a well-known traditional Chinese medicine (TCM) known for its effects on soothing the liver and alleviating depression, and is widely used in clinical settings to manage depressive symptoms. A dosage of 12.5g crude drug/kg/d of the low-polarity fraction of Radix Bupleuri (LBR) demonstrated effectiveness in treating depression in our previous study. However, the mechanism through which BR ameliorates depression remains unclear. This study aimed to explore the polar fractions of BR and their mechanisms of action in the treatment of depression. Chronic unpredictable mild stress (CUMS) rats were continuously administered BR by oral gavage for 4 weeks. Behavioral and biochemical indicators were evaluated to assess the antidepressant effects of LBR, and transcriptomics was used to explore the relevant pathways. In addition, pseudo-targeted bile acid (BA) metabonomics was used to quantify the BA profiles. Molecular biology techniques have been used to investigate the underlying mechanisms. LBR serves as a more effective active fraction with antidepressant activity. Intervention with LBR, which is characterized by a clearly defined chemical composition, significantly ameliorated depression-like behavior and biochemical indicators in rats subjected to CUMS. Notably, marked improvements were observed in the levels of total bile acids (TBAs) in the blood, liver, and ileum. Mechanistically, liver transcriptome analysis suggested that bile secretion may be a crucial pathway for alleviating depression after LBR treatment. Ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS) BA metabonomics indicated that TCA, β-MCA, γ-MCA, Tβ-MCA, and UDCA in the liver, Tβ-MCA, TCA, βMCA, GHDCA, and GLCA in the ileum, and β-MCA, CA, and DCA in the hippocampus were the potential therapeutic targets. In addition, molecular biology experiments showed that LBR exerts antidepressant effects by regulating the FXR/SHP/CYP7A1 pathway in the liver, the FXR/FGF15/ASBT pathway in the ileum, and the FXR/CREB/BDNF pathway in the hippocampus. In conclusion, LBR attenuated depression by moderating BA homeostasis through FXR and related genes within the liver-gut-brain axis.

Gegen Qinlian decoction alleviates depression-like behavior by modulating the gut microenvironment in CUMS rats

BackgroundGegen Qinlian Decoction (GQD) is a classical traditional Chinese medicine (TCM) formula primarily utilized for treating gut disorders. GQD showed therapeutic effects on several diseases in clinical and animal studies by targeting gut microbes. Our recent studies also found that GQD efficiently alleviated anxiety in methamphetamine-withdrawn mice via regulating gut microbiome and metabolism. Given that various studies have indicated the link between the gut microbiome and the development of depression, here we endeavor to explore whether GQD can manage depression disorders by targeting the gut microbiome.Methods and materialsThe depression-like model was induced in rats through chronic unpredictable mild stress (CUMS) and the depression levels were determined using the sucrose preference test (SPT). To address the depression-like behavior in rats, oral administration of GQD was employed. The colon microbiome and metabolite patterns were determined by 16s rRNA sequencing and untargeted metabolomics, respectively.ResultsWe found 6 weeks of CUMS can induce depression-like behavior in rats and 4 weeks of GQD treatment can significantly alleviate the depression-like behavior. GQD treatment can also ameliorate the histological lesions in the colon of CUMS rats. Then, CUMS increased the abundance of gut microbes, while GQD treatment can restore it to a lower level. We further discovered that the abundances of 19 bacteria at the genus level were changed with CUMS treatment, among which the abundances of Ruminococcus, Lachnoclostridium, Pygmaiobacter, Bacteroides, Pseudomonas, and Pseudomonas Family_XIII_AD3011_group were stored by GQD treatment. Besides, we identified the levels of 36 colon metabolites were changed with CUMS treatment, among which the levels of Fasciculic acid B, Spermine, Fludrocortisone acetate, alpha-Ketoglutaric acid, 2-Oxoglutaric acid, N’-(benzoyloxy)-2-(2,2-dichlorocyclopropyl) ethanimidamide, N6-Succinyl Adenosine Oleanolic acid, KQH, Ergosta-5,7,9(11),22-Tetraen-3-beta-Ol, Gentisic acid, 4-Hydroxyretinoic Acid, FAHFA (3:0/16:0), Leucine-enkephalin and N-lactoyl-phenylalanine can be restored by GQD treatment.ConclusionOur findings provide evidence supporting the therapeutic efficacy of GQD in alleviating depression-like behavior in CUMS rats, potentially being targeted on colon bacteria (especially the abundance of Ruminococcus and Bacteroides) and metabolites (especially the level of Oleanolic acid).

Effects of regulating gut microbiota by electroacupuncture in the chronic unpredictable mild stress rat model

ObjectiveThis study aims to investigate the effect of electroacupuncture (EA) treatment on depression, and the potential molecular mechanism of EA in depression-like behaviors rats. MethodsA total of 40 male Sprague Dawley rats were divided into three groups: normal control, chronic unpredictable mild stress (CUMS), and EA (CUMS + EA). The rats in CUMS and EA groups underwent chronic stress for 10 weeks, and EA group rats received EA treatment for 4 weeks starting from week 7. Body weight and behavioral tests, including the sucrose preference test (SPT), the forced swimming test (FST), and the open field test (OFT) were monitored. Gut microbiota composition was assessed via 16S rDNA sequencing, and lipid metabolism was analyzed by using UPLC-Q-TOF/MS technology. ResultsIn comparison to CUMS group, EA could improve the behavior including bodyweight, immovability time, sucrose preference index, crossing piece index and rearing times index. After 4 weeks of EA treatment, 5-HT in hippocampus, serum and colon of depressive rats were simultaneously increased, indicating a potential alleviation of depression-like behaviors. In future studies revealed that EA could regulate the distribution and functions of gut microbiota, and improve the intestinal barrier function of CUMS rats. The regulation of intestinal microbial homeostasis by EA may further affect lipid metabolism in CUMS rats, and thus play an antidepressant role. ConclusionThis study suggested that EA has potential antidepressant effects by regulating gut microbiota composition and abundance, subsequently affecting lipid metabolism.

Deep brain stimulation targeted at lateral hypothalamus-medial forebrain bundle reverses depressive-like symptoms and related cognitive deficits in rat: Role of serotoninergic system

The aim of the study is to understand the rationale behind the application of deep brain stimulation (DBS) in the treatment of depression. Male Wistar rats, rendered depressive with chronic unpredictable mild stress (CUMS) were implanted with electrode in the lateral hypothalamus-medial forebrain bundle (LH-MFB) and subjected to deep brain stimulation (DBS) for 4 h each day for 14 days. DBS rats, as well as controls, were screened for a range of parameters indicative of depressive state. Symptomatic features noticed in CUMS rats like the memory deficit, anhedonia, reduction in body weight and 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels in mPFC and elevated plasma corticosterone were reversed in rats subjected to DBS. DBS arrested CUMS induced degeneration of 5-HT cells in interfascicular region of dorsal raphe nucleus (DRif) and fibers in LH-MFB and induced dendritic proliferation in mPFC neurons. MFB is known to serve as a major conduit for the DRif-mPFC serotoninergic pathway. While the density of serotonin fibers in the LH-MFB circuit was reduced in CUMS, it was upregulated in DBS-treated rats. Furthermore, microinjection of 5-HT1A receptor antagonist, WAY100635 into mPFC countered the positive effects of DBS like the antidepressant and memory-enhancing action. In this background, we suggest that DBS at LH-MFB may exercise positive effect in depressive rats via upregulation of the serotoninergic system. While these data drawn from the experiments on rat provide meaningful clues, we suggest that further studies aimed at understanding the usefulness of DBS at LH-MFB in humans may be rewarding.

Luteolin promotes neuronogenesis in hippocampus of chronic unpredictable mild stress rats and primary hippocampus of fetal rats.

To investigate the effects of luteolin on chronic unpredictable mild stress (CUMS)-induced depressive rats and corticosterone (CORT)-induced depressive primary hippocampal neurons, and to elucidate the mechanism behind the action. The antidepressant mechanism of luteolin was studied by using CUMS rat model and primary hippocampal neurons in fetal rats. In vivo, novelty suppressed feeding, open-field and sucrose preference tests as well as Morris water maze were evaluated. The content of brain derived neurotrophic factor (BDNF), 5-hydroxytryptamine (5-HT), norepinephrine (NE), and dopamine (DA) in serum were detected by enzyme-linked immunosorbent assay. The mechanisms of luteolin were explored based on neurotrophin and hippocampal neurogenesis, and proliferation. Survival of the septo-temporal axis in hippocampus was assayed using the 5-bromo-2-deoxyuridine (BrdU), the expression of BDNF, neurotrophin-3 (NT-3), and nerve growth factor (NGF) in hippocampus dentate gyrus region were measured by Western-blotting. In vitro, BDNF, NT-3, tropomyosin receptor kinase B (TrkB), and phosphorylated cyclic adenosine monophosphate responsive element binding protein (p-CREB) were detected through the high content analysis (HCA) to investigate neurotrophin and apoptosis. Induction of CUMS in rats induced depressive symptoms, while luteolin significantly enhanced sucrose consumption, decreased feeding latency, increased locomotor activity, escape latency, distance of target quadrant and regulated the content of depressive-like biomarkers. Histology analysis revealed that luteolin increased the abundance of new born neurons that had been labeled with BrdU, BrdU + neuronal nuclear antigen, and BrdU + doublecortin in septo-temporal axis of S2 (mid-septal) and T3 (mid-temporal). Moreover, expression of BDNF, NT-3, and NGF increased significantly in the septo-temporal axis of S2 and T3. HCA showed increased expression of BDNF, NT-3, TrkB and p-CREB in primary hippocampal neurons. The results provided direct evidence that luteolin has an antidepressant effect and could effectively promote the regeneration of the septotemporal axis nerve and hippocampal neuronutrition, which suggested that the antidepressant effect of luteolin may be related to hippocampal neurogenesis.

MiRNA-103-3p promotes neural cell autophagy by activating Wnt/β-catenin signaling via targeting rab10 in a rat model of depression

To explore the neuroprotective role of Rab10 gene in depression and the mechanism mediating its effect. Forty-eight male SD rats were randomized into a control group and 3 chronic unpredictable mild stress (CUMS) groups (n=12). The rats in the latter 3 groups were subjected to injections of normal saline, an adeno-associated viral (AAV) vector, or a Rab10-overexpressing AAV vector in the lateral ventricle after CUMS modeling. The depressive behavioral changes of the rats were assessed using behavioral tests. The TargetScan database was used to predict the miRNA interacting with Rab10 and the binding sites. The interaction between miRNA-103-3p and Rab10 was investigated using dual-luciferase and radioimmunoprecipitation (RIP) assay. The effect of corticosterone treatment on PC12 cell viability was assessed with CCK-8 assay. In corticosterone-stimulated PC12 cells, the changes in BDNF, CREB, p62, Beclin-1, Wnt3a, Gsk3β, phosphorylated (p)-Gsk3β, and β-catenin protein expressions following transfection with the Rab10-overexpressing AAV vector and a miRNA-103-3p inhibitor, alone or in combination, were analyzed using qRT-PCR and Western blotting. Injection of Rab10-overexpressing AVV vector into the lateral ventricle significantly improved depressive behaviors of CUMS rats. The mRNA and proteins expression of Rab10 were significantly down-regulated in the hippocampus of CUMS rats and in corticosteronestimulated PC12 cells. Bioinformatics analysis and the results of double luciferase and RIP experiments confirmed the targeting relationship between miRNA-103-3p and Rab10. In PC12 cells, overexpression of Rab10 or silencing miRNA-103-3p activated the Wnt/β-catenin signaling pathway, up-regulated the expressions of BDNF, CREB and Beclin-1, and down-regulated the expression of p62 protein; silencing Rab10 obviously blocked the effect of miRNA-103-3p inhibitor. In mouse models of depression, miRNA-103-3p activates Wnt/β-catenin signaling via targeting rab10 to improve neural plasticity and promotes neural cell autophagy.

Shikonin ameliorates depressive- and anxiogenic-like behaviors in rats via the suppression of inflammation in the hippocampus

Shikonin is an active naphthoquinone with antioxidative, anti-inflammatory, and anticancer properties. In this study, we investigated the effects of shikonin on depressive- and anxiety-like behaviors in lipopolysaccharide- (LPS-) induced depression and chronic unpredictable mild stress (CUMS) rat models and explored the potential mechanism. First, a 14-day intraperitoneal administration of shikonin (10 mg/kg) significantly decreased immobility time in forced swimming test (FST) and increased open arm entries in elevated plus maze (EPM) test, without affecting line crossings in open field test (OFT), indicating that shikonin has anti-depressant- and anxiolytic-like effects. Second, chronic shikonin administration (10 mg/kg) reversed depressive- and anxiety-like behaviors in LPS-induced and CUMS depression models, as shown in the sucrose preference test (SPT), FST, EPM, and novel object recognition test (NORT). Finally, shikonin significantly reduced the levels of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) in hippocampus, indicating that the anti-depressant- and anxiolytic-like effects of shikonin are related to the reduction of neuroinflammation in hippocampus. These findings suggest that shikonin exerts anti-depressant- and anxiolytic-like effects via an anti-inflammatory mechanism of shikonin in the hippocampus.

Fluoxetin suppresses tau phosphorylation and modulates the interaction between tau and tubulin in the hippocampus of CUMS rats

Depression is considered a crucial psychiatric disease correlated with neuronal-dysfunctions induced by stress-stimuli. This study aimed to investigate effect of Fluoxetine (FL) on chronic unpredictable mild stress (CUMS) and explore the associated mechanisms. CUMS rat model was established by treating with lots of stresses. CUMS rats were administered FL, SB216763 (SB), Wortmannin (WT) alone or in combination. CUMS rats were administered 1 % sugar water to conduct sugar water consumption experiment. Acet-Tub, Tyr-Tub, tau46, p-tau-Ser199/202, p-tau-Ser396, p-tau-Ser231, expression was examined using immunohistochemical assay and western blotassay. Interaction between tau and tubulin was evaluated with immunoprecipitation assay. Double immunohistochemical assay was used to identify interaction between Nestin and Tau. The results indicated that FL treatment only increased sugar consumption of CUMS rats (P < 0.05), but also strengthened effects of SB and WT. FL significantly treatment decreased tau phosphorylation (p-tau) in hippocampal tissues of rats compared to those of rats in CUMS group (P < 0.05). FL treatment markedly decreased Acet-Tub and increased Tyr-Tub expression in hippocampal tissues of rats compared to those of rats in CUMS group (P < 0.05). The effects of FL treatment on p-tau down-regulation and tubulin modulation in hippocampal tissues were independent from PI3K and GSK-3 signaling pathways. FL treatment could also enhance proliferation and total tau of newborn neurons of CUMS rats. FL treatment strengthened interaction between tau and botulin in hippocampal tissues of CUMS rats. In conclusion, Fluoxetin suppressed phosphorylation of tau and modulated the interaction between tau and tubulin in hippocampus of adult CUMS rats.

NMT2 alleviates depression-like behavior in a rat model of chronic unpredictable stress: An integrated proteomic and phosphoproteomic analysis

Proteomics has been widely used to investigate multiple diseases. Combining the analyses of proteomics with phosphoproteomics can be used to further explain the pathological mechanisms of depression. In this study, depression-like behavior was induced in a rat model of chronic unpredictable mild stress (CUMS). We subsequently conducted the sucrose preference test, open field experiment, and forced swimming test to assess depressive-like behavior. Proteomic and phosphoproteomic sequencing of the hippocampal tissues from depressive-like behavior and normal rats were analyzed to identify differentially expressed proteins (DEPs) and differentially phosphorylated proteins (DPPs). Differentially expressed phosphorylated proteins (DEPPs) were obtained by intersecting the DEPs and DPPs, and functional enrichment analysis, as well as ingenuity pathway analysis (IPA), were subsequently performed. The study also investigated correlations among the DEPPs and used qRT-PCR to quantify the expression levels of key genes. Five DEPPs were identified, Gys1, Nmt2, Lrp1, Bin1, and Atp1a1, which were found to activate the synaptogenesis signaling pathway, induce mitochondrial dysfunction, and activate the phosphoinositide biosynthesis and degradation pathways. The qRT-PCR results confirmed the proteomic findings for Gys1, Nmt2, Lrp1, and Atp1a1. Importantly, inhibiting Nmt2 was found to alleviate depression-like behavior and alleviate neuronal apoptosis in the hippocampus of CUMS rats. In conclusion, we identified five DEPPs associated with the synaptogenesis signaling pathway, mitochondrial dysfunction, and phosphoinositide biosynthesis and degradation in depression. Furthermore, NMT2 may be a potential target for the treatment or diagnosis of depression. Our findings provide novel insights into the molecular mechanisms of depression.

Repetitive Transcranial Magnetic Stimulation Reversing Abnormal Brain Function in Mood Disorders with Early Life Stress: from preclinical models to clinical applications

BackgroundEarly life stress (ELS) significantly increases the risk of mood disorders and affects the neurodevelopment of the primary cortex. HypothesisModulating the primary cortex through neural intervention can ameliorate the impact of ELS on brain development and consequently alleviate its effects on mood disorders. MethodWe induced the chronic unpredictable mild stress (CUMS) model in adolescent rats, followed by applying repetitive transcranial magnetic stimulation (rTMS) to their primary cortex in early adulthood. To assess the applicability of primary cortex rTMS in humans, we recruited individuals aged 17–25 with mood disorders who had experienced ELS and performed primary cortex rTMS on them. Functional magnetic resonance imaging (fMRI) and depression-related behavioral and clinical symptoms were conducted in both rats and human subjects before and after the rTMS. ResultsIn animals, fMRI analysis revealed increased activation in the primary cortex of CUMS rats and decrease subcortical activation. Following the intervention of primary cortex rTMS, the abnormal functional activity was reversed. Similarly, in mood disorders patients with ELS, increased activation in the primary cortex and decreased activation in the frontal cortex were observed. During rTMS intervention, similar neuroimaging improvements were noted, particularly decreased activation in the primary cortex. This suggests that targeted rTMS in the primary cortex can reverse the abnormal neuroimaging. ConclusionThis cross-species translational study has identified the primary cortex as a key region in mood disorders patients with ELS. Targeting the primary cortex with rTMS can correct abnormal functional activity while improving symptoms. Our study provides translational evidence for therapeutics targeting the ELS factor of mood disorders patients.

Protective role of TRPV2 in synaptic plasticity through the ERK1/2-CREB-BDNF pathway in chronic unpredictable mild stress rats

PurposeChronic stress is a significant risk factor for mood disorders such as depression, where synaptic plasticity plays a central role in pathogenesis. Transient Receptor Potential Vanilloid Type-2 (TRPV2) Ion Channels are implicated in hypothalamic-pituitary-adrenal axis disorders. Previous proteomic analysis indicated a reduction in TRPV2 levels in the chronic unpredictable mild stress (CUMS) rat model, yet its role in synaptic plasticity during depression remains to be elucidated. This study aims to investigate TRPV2's role in depression and its underlying mechanisms. MethodsIn vivo and in vitro experiments were conducted using the TRPV2-specific agonist probenecid and ERK1/2 inhibitors SCH772984. In vivo, rats underwent six weeks of CUMS before probenecid administration. Depressive-like behaviors were assessed through behavioral tests. ELISA kits measured 5-HT, DA, NE levels in rat hippocampal tissues. Hippocampal morphology was examined via Nissl staining. In vitro, rat hippocampal neuron cell lines were treated with ERK1/2 inhibitors SCH772984 and probenecid. Western blot, immunofluorescence, immunohistochemical staining, and RT-qPCR assessed TRPV2 expression, neurogenesis-related proteins, synaptic markers, and ERK1/2-CREB-BDNF signaling proteins. ResultsDecreased hippocampal TRPV2 levels were observed in CUMS rats. Probenecid treatment mitigated depressive-like behavior and enhanced hippocampal 5-HT, NE, and DA levels in CUMS rats. TRPV2 activation countered CUMS-induced synaptic plasticity inhibition. Probenecid activated the ERK1/2-CREB-BDNF pathway, suggesting TRPV2's involvement in this pathway via ERK1/2. ConclusionThese findings indicate that TRPV2 activation offers protective effects against depressive-like behaviors and enhances hippocampal synaptic plasticity in CUMS rats via the ERK1/2-CREB-BDNF pathway. TRPV2 emerges as a potential therapeutic target for depression.

The effect of olanzapine on spatial memory impairment, depressive-like behavior, pain perception, and BDNF and synaptophysin expression following childhood chronic unpredictable mild stress in adult male and female rats

Chronic unpredictable mild stress (CUMS) method has been introduced as a rodent model of depression. On the other hand, olanzapine, as an antipsychotic, can induce antidepressant and antipsychotic effects. Also, olanzapine may improve cognitive functions. Both CUMS and olanzapine can also affect the expression level of brain-derived neurotrophic factor (BDNF) and synaptophysin, the molecular factors involved in synaptic function, and learning and memory. In this study, we investigated the effect of olanzapine on locomotor activity (using open field test), pain threshold (using hot plate), depressive-like behavior (using forced swim test), spatial learning and memory (using Morris water maze), and BDNF and synaptophysin hippocampal expression (using real-time PCR) in both male and female CUMS rats. CUMS was performed for three consecutive weeks. Olanzapine was also injected intraperitoneally at the dose of 5 mg/kg. Our data showed that olanzapine can reverse the effects of CUMS on behavioral functions and BDNF and synaptophysin expression levels in the hippocampus of both males and females. It was also shown that olanzapine effects on spatial memory, pain perception, and BDNF and synaptophysin level were stronger in females than males. In conclusion, we suggested that the therapeutic effects of olanzapine in CUMS rats may be closely related to the function of BDNF and synaptophysin. Also, the therapeutic effects of olanzapine may be stronger in females. Therefore, and for the first time, we showed that there may be a sex difference in the effects of olanzapine on behavioral and molecular changes following CUMS.

Study on the antidepressive effects and mechanism of raw and fried Ziziphi Spinosae Semen via metabolomics and gut microbiota analysis.

Ziziphi Spinosae Semen (ZSS) and fried ZSS (FZSS) have been used for treating insomnia and depression in China. However, the potential influence of chemical variations on their efficacy remains unclear. This study demonstrated that compared with ZSS, FZSS exhibited an increase in the content of seven compounds, while the fatty oil content decreased. Both ZSS and FZSS exhibited antidepressive effects in a chronic unpredictable mild stress rat model, indicating a synergistic regulation of deficiencies in 5-hydroxytryptamine in the brain and the hyperactivation of severe peripheral inflammation. ZSS demonstrated a superior modulatory effect compared with FZSS, as indicated by integrated pharmacodynamic index, metabolic profile, and relative distance value. The potential mechanism underlying their antidepressive effects involved the modulation of gut microbiota structure to alleviate excessive inflammatory responses and imbalanced tryptophan metabolism. Correlation analysis indicated that the higher fatty oil contents should be comprehensively considered as the main reason for ZSS's superior antidepressive effects, achieved through the regulation of pyroglutamic acid levels.

Quercetin alleviates chronic unpredictable mild stress-induced depression-like behavior by inhibiting NMDAR1 with α2δ-1 in rats.

Depression is a serious mental disorder and the most prevalent cause of disability and suicide worldwide. Chronic unpredictable mild stress (CUMS) can lead to a significant acceleration of depression development. Quercetin (Que) is a flavonoid compound with a wide range of pharmacological effects. Recent studies have shown that quercetin can improve CUMS-induced depression-like behavior, but the mechanism of its improvement is still unclear. α2δ-1 is a regulatory subunit of voltage-gated calcium channel, which can interact with N-methyl-D-aspartate receptor (NMDAR) to form a complex. In this study, we found that Que could inhibit the increase of α2δ-1 and NMDAR expression in rat hypothalamus induced by CUMS. In pain, chronic hypertension and other studies have shown that α2δ-1 interacts with the NMDAR to form a complex, which subsequently affects the expression level of NMDAR. Consequently, the present study aimed to investigate the antidepressant effect of Que invivo and invitro and to explore its mechanism of action in terms of the interaction between α2δ-1 and NMDAR. Rats were randomly exposed to two stressors every day for 4 weeks to establish a CUMS rat model, then sucrose preference test (SPT), forced swimming test (FST), tail suspension test (TST), and open field test (OFT) were performed to detect the behavior of CUMS rats, so as to evaluate whether the CUMS rat model was successfully established and the improvement effect of Que on CUMS-induced depression-like behavior in rats. Experimental techniques such as serum enzyme-linked immunosorbent assay (ELISA), immunofluorescence, Western blot, and co-immunoprecipitation, as well as invitro experiments, were used to investigate the mechanisms by which Que exerts its antidepressant effects. Behavioral and ELISA test results showed that Que could produce a reduction in the excitability of the hypothalamic-pituitary-adrenal (HPA) axis in CUMS rats and lead to significant improvements in their depressive behavior. Western blot, immunofluorescence, and co-immunoprecipitation experiments showed that Que produced a decrease in NMDAR1 and α2δ-1 expression levels and interfered with α2δ-1 and NMDAR1 binding. In addition, the neural regulation mechanism of Que on antidepressant effect in PC12 cells knocked out α2δ-1 gene was further verified. Cellular experiments demonstrated that Que led to a reversal of up-regulation of NMDAR1 and α2δ-1 expression levels in corticosterone-injured PC12 cells, while Que had no effects on NMDAR1 expression in PC12 cells with the α2δ-1 gene knockout. Que has a good antidepressant effect and can significantly improve the depression-like behavior caused by CUMS. It exerts antidepressant effects by inhibiting the expression level of α2δ-1, interfering with the interaction between α2δ-1 and NMDAR, and then reducing the excitability of the HPA axis.

Bergamot essential oil improves CUMS-induced depression-like behaviour in rats by protecting the plasticity of hippocampal neurons.

Bergamot essential oil (BEO) is an extract of the bergamot fruit with significant neuroprotective effect. This study was to investigate the effects and the underlying mechanism of BEO in mitigating depression. GC-MS were used to identify its constituents. Antidepressive properties of BEO were evaluated by sucrose preference test (SPT), force swimming test (FST) and open field test (OFT). Nissl staining was used to determine the number of Nissl bodies in hippocampus (HIPP) of rats. Changes in HIPP dendritic length and dendritic spine density were detected by Golgi-Cox staining. Immunohistochemistry and Western blot were used to detect the postsynaptic density protein-95 (PSD-95) and synaptophysin (SYP) in the HIPP of rats. The enzyme-linked immunosorbent assay was used to determine the 5-hydroxytryptamine (5-HT), insulin-like growth factor 1 (IGF-1) and interleukin-1β (IL-1β) in the HIPP, serum and cerebrospinal fluid (CSF) of rats. Inhaled BEO significantly improved depressive behaviour in chronic unpredictable mild stress (CUMS) rats. BEO increased Nissl bodies, dendritic length and spine density, PSD-95 and SYP protein in the HIPP. Additionally, BEO upregulated serum 5-HT, serum and CSF IGF-1, while downregulating serum IL-1β. Collectively, inhaled BEO mitigates depression by protecting the plasticity of hippocampal neurons, hence, providing novel insights into treatment of depression.

Stable Isotope Tracer Technique and Network Pharmacology to Reveal Antidepressant Targets and Active Components of Xiaoyao San.

In recent years, the research of mitochondrial dysfunction in depression has drawn the focus of researchers. Our research group previously found that Xiaoyao San (XYS) has improved the mitochondrial structure and the blocked tricarboxylic acid cycle (TCA cycle) in the hippocampal tissue of chronic unpredictable mild stress (CUMS) rats. However, the specific targets and active components of XYS remain unclear, and the potential to improve hippocampal mitochondrial TCA cycle disorder was also unexplored. In this research, a strategy to combine stable isotope-resolved metabolomics (SIRM), network pharmacology and transmission electron microscopy (TEM) was used to explore the potential, targets of action, and active components of XYS to improve hippocampal mitochondrial TCA cycle disorder of CUMS rats. The results of TEM showed that the ultrastructure of hippocampal mitochondria could be improved by XYS. A combination of SIRM and molecular docking showed that pyruvate carboxylase (PC), ATP citrate lyase (ACLK), glutamate dehydrogenase (GLDH), glutamate oxaloacetate transaminase (GOT) and pyruvate dehydrogenase (PDH) were targets of XYS to improve TCA cycle disorder. In addition, troxerutin was found to be the most potential active component of XYS to improve TCA cycle disorder. The above research results can provide new insights for the development of antidepressant drugs.