Chronic Unpredictable Mild Stress Mice Research Articles

Anti-Inflammation Relieving Heart Dysfunction and Depressive Behaviors of Mice Under Myocardial Infarction and Chronic Stress

Abstract Background: Myocardial infarction (MI) induces high morbidity all over the world. Patients with MI are more vulnerable to depression, and depression worsens their prognosis. Inflammatory response is the primary pathophysiological mechanism of MI combined with depression. Therefore, MI and depression would benefit from attenuating inflammation. Objectives: To explore the anti-inflammation effect in relieving heart dysfunction and depressive behaviors of mice under MI and chronic stress. Materials and Methods: A total of 40 male C57BL/6J mice were given sham or MI surgery, and the success rate of the surgery was 80%. Hence, 32 mice survived surgery and were distributed as 8 in each group of study. Then, unpredictable chronic mild stress (UCMS) or Anshen Buxin Liuwei pills (ABL pills) group were applied to some MI mice, and the mice were divided into different groups, including sham group, MI group, MI + UCMS group, and MI + UCMS + ABL pills group (n = 8). After a 2-week treatment, the mice underwent the sucrose preference test, and echocardiography before sacrifice. Then, the mice were sacrificed for pathological detection and inflammatory cytokines detection. Results: Compared with mice in the sham group, those mice had lower left ventricular ejection fraction (LVEF) (51.25 ± 9.92 vs. 12.18 ± 8.46, 20.95 ± 16.40, 29.55 ± 13.33%, P< 0.05) and left ventricular fractional shortening (LVFS) (21.12 ± 6.82 vs. 5.57 ± 4.0, 9.89 ± 8.03, 14.0 ± 6.65%, P< 0.05) in the MI, MI + UCMS, and MI + UCMS + ABL pills groups. ABL pills could reverse cardiac dysfunction for the significant elevation of LVEF and LVFS. The hematoxylin and eosin staining presented left ventricular (LV) enlargement, inflammatory cell infiltration, and myocardial fibrosis formation in MI and MI + UCMS mice. While ABL pills reversed the pathological changes induced by ligation of the left anterior descending. The enzyme-linked immunosorbent assay detection showed that MI and MI + UCMS elevated the concentrations of cardiac tumor necrosis factor-α (TNF-α) and tumor necrosis factor receptor 1 (TNFR1), which were reduced by ABL pills. ABL pills significantly reversed the depressive behaviors of mice with MI + UCMS (82.97 ± 3.04 vs. 76.07 ± 7.84%, P< 0.05). MI + UCMS group had a higher level of cortex TNFR1 than sham and MI, while ABL pills reversed the elevation (P > 0.05). Conclusions: Anti-inflammation treatment effectively improves cardiac function and depressive behaviors via inhibiting TNF-α/TNFR1.

DFO treatment protects against depression-like behaviors and cognitive impairment in CUMS mice

Depression has several negative effects on emotion as well as learning and memory abilities. Previous studies showed that depression could exacerbate inflammation, which in turn further aggravated depression. Deferoxamine (DFO) is a chelating agent binding iron and aluminium, and is clinically applied to treat acute ion poisoning and hemochromatosis. Researches showed that it could reduce inflammation via increasing the expression of hypoxia-inducible factor-1alpha (HIF-1α). Here, we established a chronic unpredictable mild stress (CUMS) model to investigate whether DFO exerted a neuroprotective function in depression. The results demonstrated that CUMS (4 weeks) effectively induced depression-like behaviors in mice based on sucrose preference test (SPT), forced swim test (FST), tail suspension test (TST), open field test (OFT), and elevated plus-maze test (EPT). It also brought cognitive deficits based on Morris water maze (MWM) test and the impairment of synaptic plasticity based on in vivo electrophysiological recordings. Additionally, CUMS exposure significantly decreased the expression of hippocampal synapse related proteins and the spine density of neurons in the DG region, accompanied by increasing the expression of hippocampal inflammatory cytokines, and promoted the activation of microglia in the hippocampus. The expression of HIF-1α was down-regulated as expected. However, DFO distinctly reversed the CUMS-induced impairments. The mechanism is associated with the DFO inhibition of inflammation by upregulating HIF-1 expression, thereby alleviating a series of pathology changes. Together, these findings suggest that DFO likely plays a protective role in cognitive impairments and synaptic plasticity deficits resulting from depression.

Achyranthes aspera ameliorates stress induced depression in mice by regulating neuroinflammatory cytokines

Background and aimAchyranthes aspera Linn. (A. aspera) (family: Amaranthaceae) is highly recognized in ethnomedicine and traditional systems of Indian medicine as a nervine restorative for several psychiatric disorders. Study presented here was designed to appraise the antidepressant-like effects of A. aspera in murine model of chronic unpredictable mild stress (CUMS) induced depression. Experimental procedures-Rodents were exposed to different stressor in unpredictive manner during CUMS protocol once a day for 4 weeks. Mice were intraperitoneally injected with A. aspera extract (2.5, 5 and 10 mg/kg) or fluoxetine (10 mg/kg) or betaine (20 mg/kg) once daily during day 15–28 of the CUMS protocol. Sucrose preference, motivation and self-care, immobility latency and plasma corticosterone were evaluated after 24 h of last stressor. After behavioral assessments TNF-α, Il-6 and BDNF immunocontent was determined in hippocampus and prefrontal cortex. Results and conclusionA. aspera extract as well as betaine improved sucrose preference, increased grooming frequency and latency in splash test and ameliorated depression-like condition in CUMS mice in Porsolt test. A. aspera treatment decreased the elevated plasma corticosterone and reversed the effect of CUMS on TNF-α, Il-6 and BDNF immunocontent in mice. The results of the present study suggest A. aspera as a promising indigenous medicine for stress associated neurobehavioral and comorbid complications.

Knockdown of miRNA-134-5p rescues dendritic deficits by promoting AMPK-mediated mitophagy in a mouse model of depression

Neuronal dendrites and dendritic spines are essential for normal synaptic transmission and may be critically involved in the pathophysiology of various neurological disorders, including depression. Emerging data supports the role of mitochondria in dendritic protrusions in modulating the development and morphological plasticity of spines. Mitophagy, a mitochondria-specific form of autophagy, is the fundamental process of clearing damaged mitochondria to maintain cellular homeostasis. As a brain-specific microRNA, miR-134 is localized to the synaptodendritic compartment of hippocampal neurons and negatively regulates the development of dendritic spines. However, the role of miR-134 in mitophagy related to dendritic deficits in the pathophysiology of depression remains unclear. In this study, we showed that miR-134-5p knockdown abrogated depression-like behavioral symptoms and corrected aberrant spine morphology in hippocampal neurons of chronic unpredictable mild stress (CUMS) mice. Moreover, knockdown of miR-134-5p triggered autophagy in dendrites, improved mitochondrial impairment, and induced the generation of autophagosomes in the hippocampus of CUMS mice. We further found that AMP-activated protein kinase (AMPK), which mediates the impairment of defective mitochondria via mitophagy, can bind directly to miR-134-5p and is negatively regulated by this miRNA. This study demonstrates that miR-134-5p exerts an enormous effect on dendritic deficits by promoting AMPK-mediated mitophagy and provides a potential new target for antidepressant drug research and development.

Effects of repeated drug administration on behaviors in normal mice and fluoxetine efficacy in chronic unpredictable mild stress mice

Mental disorders are characterized by high incidence and high recurrence rates, and only part of patients responded to drug medication. In this case, substantial preclinical investigations are needed. Most antipsychotics taken daily orally in clinics are administered through injection, oral gavage, or minipum implant in rodents, which may induce stress and affect the results of behavioral tests. How drug administrations on behaviors and drug efficacy remains an unsolved problem. In this study, we compared the intraperitoneal injection (IP), intragastric administration (IG), and tail vein injection (TVI) on behaviors, as well as the difference between administration-induced stress and chronic unpredictable mild stress (CUMS). Next, we studied the effects of IG on CUMS model and drug efficacy. We found that IP, IG, and TVI, especially IG, induced a behavior-like phenotype of depression and anxiety, which we call the “CUMS-like behaviors”. However, such behaviors were not equal to depression. When treated CUMS mice with saline by gavage, they didn't show any aggravated phenotype compared with CUMS alone. We observed that fluoxetine by intraperitoneal injection was more effective than intragastric administration. Our study confirmed that repeated administrations lead to CUMS-like behaviors. Although these behaviors are not depression, they have adverse effects on drug efficacy.

Effects of the Bark Resin Extract of Garcinia nigrolineata on Chronic Stress-Induced Memory Deficit in Mice Model and the In Vitro Monoamine Oxidases and β-Amyloid Aggregation Inhibitory Activities of Its Prenylated Xanthone Constituents.

The present study describes investigation of the effects of the bark resin extract of Garcinia nigrolineata (Clusiaceae) on the cognitive function and the induction of oxidative stress in both frontal cortex and hippocampus by unpredictable chronic mild stress (UCMS). By using behavioral mouse models, i.e., the Y-maze test, the Novel Object Recognition Test (NORT), and the Morris Water Maze Test (MWMT), it was found that the negative impact of repeated mild stress-induced learning and memory deficit through brain oxidative stress in the UCMS mice was reversed by treatment with the bark resin extract G. nigrolineata. Moreover, the prenylated xanthones viz. cowagarcinone C, cowaxanthone, α-mangostin, cowaxanthone B, cowanin, fuscaxanthone A, fuscaxanthone B, xanthochymusxanthones A, 7-O-methylgarcinone E, and cowagarcinone A, isolated from the bark resin of G. nigrolineata, were assayed for their inhibitory activities against β-amyloid (Aβ) aggregation and monoamine oxidase enzymes (MAOs).

The Beneficial Effects of Citrus kawachiensis Peel on Neurogenesis in the Hippocampus and Gut Microbiota Changes in a Chronic Unpredictable Mild Stress Mouse Model

We previously reported that the dried peel powder of Citrus kawachiensis, a citrus product of Japan, exerted anti-inflammatory and neuroprotective effects in the brains of transient global cerebral ischemia model mice. It also ameliorated the hyperphosphorylation of Tau protein and the suppression of neurogenesis in the brains of the senescence-accelerated mouse-prone 8 aging model. Chronic unpredictable mild stress (CUMS) induces anxiety-like behavior, changes the composition of the gut microbiota and suppresses neurogenesis in the hippocampus. Therefore, we herein examined the effects of the dried peel powder of C. kawachiensis in a CUMS mouse model: CUMS enhanced locomotor activity, shown as the distance travelled in the open field test at the beginning of the test, while the C. kawachiensis treatment suppressed this increase. The C. kawachiensis treatment also prevented CUMS-induced decreases in hippocampal neurogenesis. The CUMS treatment changed the composition of the gut microbiota by reducing the abundance of Lactobacillus and increasing that of Bacteroides, whereas the C. kawachiensis treatment attenuated these changes. Collectively, the present results suggest that the dried peel powder of C. kawachiensis exerts neuroprotective effects in the brain and maintains the condition of the microbiome under mild stress.

Selective activation of ABCA1/ApoA1 signaling in the V1 by magnetoelectric stimulation ameliorates depression via regulation of synaptic plasticity

SummaryEmerging evidence suggests that dysfunction of the visual cortex may be involved in major depressive disorder (MDD). However, the underlying mechanisms remain unclear. We previously established that combined magnetic stimulation system treatment (c-MSST) resulted in an antidepressant effect in mice. In the present study, we found that V1-targeted c-MSST induced significant antidepressant effects in chronic unpredictable mild stress (CUMS)- and lipopolysaccharide (LPS)-treated mice. Proteomic screening investigation and repeatable validation revealed that expression of the V1 neuronal ATP-binding cassette transporter A1 (ABCA1) and apolipoprotein A-1 (ApoA1) was downregulated in CUMS mice, an effect that was normalized by c-MSST. Neuron-specific knockdown of ABCA1 in V1 blocked c-MSST’s antidepressant effects. Mechanistically, CUMS reduced dendritic spine density and long-term plasticity in V1, and these deficits were reversed by c-MSST. V1-targeted c-MSST was found to induce rapid antidepressant effects that are mediated by alterations in synaptic plasticity via the ABCA1/ApoA1 signaling pathway in V1.

Knockdown of FSTL1 inhibits microglia activation and alleviates depressive-like symptoms through modulating TLR4/MyD88/NF-κB pathway in CUMS mice

Inflammatory processes play a pivotal role in the development and progression of depression. Since Follistatin-like protein 1 (FSTL1) has been identified as a novel inflammatory protein, a variety of studies suggest that targeting FSTL1 may be useful in the treatment of diseases in which inflammation plays a central role. In the study, we aimed to investigate the causal relationship between FSTL1 signaling and the development of depression. To explore the effect and mechanism of FSTL1 on chronic stress-induced depression, the chronic unpredictable mild stress (CUMS) paradigm was used. Animals subjected to CUMS for 4 weeks exhibited depressive-like symptoms, including decreased sucrose preference and obvious behavioral despair, concomitantly with increased FSTL1 level in the hippocampus. In contrast, mice with FSTL1 knockdown abolished CUMS induced depression-like and anxiety-like behaviors. Moreover, FSTL1 knockdown reversed CUMS induced synaptic plasticity deficits in the PP-DG pathway of the hippocampus and increased the expression of synaptic associated proteins in the hippocampus of CUMS exposed mice. Microglia activation induced by CUMS paradigm could be significantly inhibited by FSTL1 knockdown. Furthermore, Western blot revealed that FSTL1 knockdown considerably decreased the expression of indicated molecules TLR4/MyD88/NF-κB signaling pathway in CUMS exposed mice. In conclusion, our data implies that FSTL1 may modulate the microglial activation through TLR4/MyD88/NF-κB signaling, which affects depression-like behaviors and synaptic function deficits induced by CUMS in mice. These results suggested that the role of FSTL1 in mediating microglia-related mechanisms in depression may shed light on developing new therapeutic strategies to treat this prevalent disease.

Swimming exercise reverses chronic unpredictable mild stress-induced depression-like behaviors and alleviates neuroinflammation and collapsing response mediator protein-2-mediated neuroplasticity injury in adult male mice.

ObjectiveImpaired neuroplasticity and neuroinflammation are vital in the mechanisms of depression. Exercise alleviates depressive symptoms and ameliorates body functions. Swimming is one of the most common exercises; however, whether swimming alters depressive behaviors and the underlying mechanism has not been fully elucidated.MethodsMale C57/BL6J mice were exposed to chronic unpredictable mild stress (CUMS) for 6 weeks and then were subjected to a 5-week swimming program. Behavioral test, including sucrose preference test (SPT), open field test (OFT), elevated plus-maze (EPM) test, and tail suspension test (TST), was conducted to assess the anxiety-like and depressive behaviors. Western blotting and immunofluorescence staining were carried out after tissue collection.ResultsThis study showed that CUMS-induced depressive behaviors but swimming exercise increased sucrose preference in SPT, increased time and velocity in the center on OFT, decreased time in the closed arm, increased time in the open arm in EPM, and decreased immobility time in TST. We further found swimming exercise increased hippocampal collapsing response mediator protein-2 (CRMP2) expression and decreased p-CRMP2 expression in CUMS mice. CUMS inhibited the levels of α-tubulin and CRMP2, and the expression of ionized calcium-binding adaptor molecule 1 and caspase-1, whereas swimming reversed them in CUMS-exercised mice.ConclusionOur study confirmed that swimming exercise reverses CUMS-induced depressive behaviors, and neuroinflammation and CRMP2-mediated neuroplasticity are involved, which may provide a new insight into the antidepression therapy of exercise.

Gut Microbiota-Mediated Elevated Production of Secondary Bile Acids in Chronic Unpredictable Mild Stress.

A growing body of evidence suggests that gut microbiota could participate in the progression of depression via the microbiota–gut–brain axis. However, the detailed microbial metabolic profile changes in the progression of depression is still not fully elucidated. In this study, a liquid chromatography coupled to mass spectrometry-based untargeted serum high-throughput metabolomics method was first performed to screen for potential biomarkers in a depressive-like state in a chronic unpredictable mild stress (CUMS)-induced mouse model. Our results identified that the bile acid and energy metabolism pathways were significantly affected in CUMS progression. The detailed bile acid profiles were subsequently quantified in the serum, liver, and feces. The results showed that CUMS significantly promoted the deconjugation of conjugated bile acid and secondary bile acid biosynthesis. Furthermore, 16S rRNA gene sequencing revealed that the increased secondary bile acid levels in the feces positively correlated with Ruminococcaceae_UCG-010, Ruminococcus, and Clostridia_UCG-014 abundance. Taken together, our study suggested that changes in family Ruminococcaceae abundance following chronic stress increased biosynthesis of deoxycholic acid (DCA), a unconjugated secondary bile acid in the intestine. Aberrant activation of secondary bile acid biosynthesis pathway thereby increased the hydrophobicity of the bile acid pool, which might, in turn, promoted metabolic disturbances and disease progression in CUMS mice.

Gene expression profiling reveals candidate biomarkers and probable molecular mechanisms in chronic stress

ABSTRACT Chronic stress refers to nonspecific systemic reactions under the over-stimulation of different external and internal factors for a long time. Previous studies confirmed that chronic psychological stress had a negative effect on almost all tissues and organs. We intended to further identify potential gene targets related to the pathogenesis of chronic stress-induced consequences involved in different diseases. In our study, mice in the model group lived under the condition of chronic unpredictable mild stress (CUMS) until they expressed behaviors like depression which were supposed to undergo chronic stress. We applied high-throughput RNA sequencing to assess mRNA expression and obtained transcription profiles in lung tissue from CUMS mice and control mice for analysis. In view of the prediction of high-throughput RNA sequences and bioinformatics software, and mRNA regulatory network was constructed. First, we conducted differentially expressed genes (DEGs) and obtained 282 DEGs between CUMS (group A) and the control model (group B). Then, we conducted functional and pathway enrichment analyses. In general, the function of upregulated regulated DEGs is related to immune and inflammatory responses. PPI network identified several essential genes, of which ten hub genes were related to the T cell receptor signaling pathway. qRT-PCR results verified the regulatory network of mRNA. The expressions of CD28, CD3e, and CD247 increased in mice with CUMS compared with that in control. This illustrated immune pathways are related to the pathological molecular mechanism of chronic stress and may provide information for identifying potential biomarkers and early detection of chronic stress.

Suppressive Effects of Gelsemine on Anxiety-like Behaviors Induced by Chronic Unpredictable Mild Stress in Mice.

Gelsemine is an active principle and a major alkaloid found in Gelsemium genus of plants belonging to the Loganiaceae family. The aim of the present study was to explore whether gelsemine exerts anxiolytic effects on a mouse model of chronic-unpredictable-mild-stress (CUMS)-induced anxiety-like behaviors. NOD-like receptor protein 3 (NLRP3) inflammasome, downregulated cAMP-response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) were also evaluated as potential mechanisms. First, gelsemine reversed a CUMS-induced decrease in body-weight gain in mice. Next, gelsemine alleviated CUMS-induced anxiety-like behaviors, as evidenced by the increased distance traveled in the central zone of the open-field test, both the increased percentage of time spent and distance traveled in the light compartment, the increased number of transitions between compartments in the light/dark-transition test, and the increased percentage of entries and time spent in the open arm of the elevated plus-maze. In addition, gelsemine decreased the levels of pro-inflammatory cytokines, including interleukin (IL)-1β and IL-6, in the hypothalamus and hippocampus of CUMS mice. Interestingly, further investigations revealed that gelsemine inhibited the CUMS-induced activation of NLRP3-inflammasome pathways and downregulated CREB and BDNF overexpression in the hypothalamus. In summary, gelsemine alleviated anxiety-like behaviors in the CUMS-induced mouse model. Gelsemine exerted its anxiolytic effects by modulating the NLRP3 and CREB/BDNF pathways.

MST1-knockdown protects against impairment of working memory via regulating neural activity in depression-like mice.

We reported that over-expression of MST1 induced the impairment of spatial memory via disturbing neural oscillation patterns in mice. Meanwhile, the P-MST1 is increased in the hippocampus after chronic unpredictable mild stress (CUMS). However, it is unclear if MST1 knockdown protects against stress-induced memory deficits via modulating neural activities. In the study, a CUMS mouse model was established and an intrahippocampal injection of AAV-shMST1 was used to knockdown MST1 in the hippocampus. The data showed that there were memory deficits with over-expressed P-MST1 level in CUMS mice. However, MST1 knockdown can significantly prevent the damages of CUMS-induced working memory and synaptic plasticity via regulating neural oscillation patterns. It suggests that MST1 down-regulation effectively protected against stress-induced behavioral dysfunctions. Moreover, as a more convenient way, neural oscillation analysis could provide some assistance for the auxiliary diagnosis and treatment of depression.

Regulation of the kynurenine/serotonin pathway by berberine and the underlying effect in the hippocampus of the chronic unpredictable mild stress mice

BackgroundDepression is a common mental disorder and is one of the main causes of disability. Berberine (BBR), the major constituent alkaloid originally from the famous Chinese herb Huanglian (Coptis chinensis), has been shown to exert antidepressant-like effects. This study was to investigate the hypothesis that BBR treats depressive-like behavior by shifting the balance of the kynurenine (KYN)/serotonin (5-HT) pathway toward the 5-HT pathway through downregulated indoleamine 2,3-dioxygenase 1 (IDO1), monoamine oxidase A (MAOA) and upregulated dopamine decarboxylase (DDC) in hippocampus. MethodA chronic unpredictable mild stress (CUMS) mice model of depression was established via 21 days unpredictable stimulation. Then the mice were randomly assigned into six groups, namely control, model, fluoxetine [FLU, (10 mg/kg)], BBRL (25 mg/kg), BBRM (50 mg/kg), and BBRH (100 mg/kg) groups. Behavioral assessments were conducted to evaluate the antidepressant effects of BBR. The levels of 5-HT, KYN, tryptophan (TRP), and 5-hydroxyindoleacetic acid (5-HIAA) in hippocampus were estimated using high performance liquid chromatography (HPLC). The mRNA and protein levels of DDC, MAOA and IDO1 in hippocampus were detected by real-time quantitative polymerase chain reaction (qRT-PCR) and western blot (WB), respectively. ResultThe results showed that a successful CUMS mice model was established through 21 days of continuous unpredictable stimulation, as indicated by the significant decrease in locomotor activity and increase in immobility time, reduction in body weight and sucrose preference rate etc. Compared with the normal group, the concentrations of KYN/TRP had significantly increased (p## <0.01) and 5-HT/5-HIAA had decreased (p#<0.05) at day 21 in the control group, but then improved after drug treatment with FLU and BBR. Compared with the normal group, the mRNA of IDO1 and MAOA were significantly upregulated (p#<0.05) in the control group, MAOA and IDO1 gene were downregulated by FLU and BBR treatment. Protein expressions of IDO1 and MAOA was significantly increased (p#<0.05) and DDC downregulated (p##<0.01). BBR treatment downregulated IDO1 and MAOA, upregulated DDC. ConclusionsBBR reversed the abnormalities of the KYN/5-HT pathway in depressed mice and achieved an excellent antidepressant effect. Its direct impact may be observed as changes in biological indicators in mice hippocampus tissue.

Xiaoyaosan ethyl acetate fraction alleviates depression-like behaviors in CUMS mice by promoting hippocampal neurogenesis via modulating the IGF-1Rβ/PI3K/Akt signaling pathway

Ethnopharmacological relevanceXiaoyaosan (XYS), a representative and classic traditional Chinese medicine (TCM) prescription with function of dispersing stagnated liver and strengthening spleen, has been used for thousands of years to treat depression. XYS’ anti-depression effect has been demonstrated both clinically and experimentally; however, the material basis for this effect has yet to be elucidated. Aim of the studyThis study aimed to evaluate the impact and underlying action mechanism of XYS’ antidepressant active component (Xiaoyaosan ethyl acetate fraction, XYSEF) against chronic unpredictable mild stress (CUMS)-induced depression-like behavior in mice. Materials and methodsFirst, we established a behavioral despair depression mouse model to preliminarily determine the effective antidepressant dose of XYSEF. Then, we created a CUMS mouse model and used various classic behavioral tests, including SPT, ST, NFST, and TST, to assess XYSEF's antidepressant properties. IGF-1 levels in mouse serum and hippocampus were quantified using ELISA. The average optical density of Nissl bodies in the mouse hippocampal CA3 region was determined utilizing toluidine blue staining. Brdu and DCX expression in the hippocampal dentate gyrus (DG) was assayed using the immunofluorescence method. IGF-1Rβ, PI3K, p-PI3K, Akt, p-Akt, Caspase-3, and cleaved Caspase-3 protein levels in the hippocampus were determined with Western blot. ResultsThe behavioral despair mouse model findings showed that 9.1 and 40 g/kg of XYSEF both significantly shortened the immobility time of mice, suggesting that the effective dose range was 9.1–40 g/kg. Compared to the CUMS mouse model, XYSEF at 20 and 40 g/kg markedly increased the sucrose preference percentage in the SPT and grooming time in the ST, shortened the immobility time in the TST and the feeding latency in the NSFT, and reversed the downregulated IGF-1 content in mouse serum and hippocampus. In addition, XYSEF amplified the average optical density of Nissl bodies in the hippocampal CA3 region, promoted Brdu and DCX expression in DG, and diminished IGF-1Rβ, p-PI3K/PI3K, p-Akt/Akt, and cleaved Caspase-3/Caspase-3 protein levels in the hippocampi of CUMS mice. ConclusionXYSEF acted as an antidepressant in mice exhibiting CUMS-induced depression-like behaviors, possibly by promoting hippocampal neurogenesis, reducing neuronal apoptosis, and inhibiting the over-activation of the IGF-1Rβ/PI3K/Akt pathway.

A Network Pharmacology-Based Study on Antidepressant Effect of Salicornia europaea L. Extract with Experimental Support in Chronic Unpredictable Mild Stress Model Mice.

To investigate the pharmacodynamic material basis, mechanism of actions and targeted diseases of Salicornia europaea L. (SE) based on the network pharmacology method, and to verify the antidepressant-like effect of the SE extract by pharmacological experiments. Retrieval tools including Chinese medicine (CM), PubMed, PharmMapper, MAS 3.0 and Cytoscape were used to search the components of SE, predict its targets and related therapeutic diseases, and construct the "Component-Target-Pathway" network of SE for central nervous system (CNS) diseases. Further, protein-protein interaction (PPI) network, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) function annotation of depression-related targets were analyzed to predict the antidepressant mechanism of SE. Chronic unpredictable mild stress (CUMS) model was used to construct a mouse model with depression-like symptoms. And the animals were randomly divided into 6 groups (n=10) including the normal group (nonstressed mice administered with distilled water), the CUMS group (CUMS mice administered with distilled water), the venlafaxine group (CUMS mice administered with venlafaxine 9.38 mg/kg), SE high-, medium-, and low-dose groups (CUMS mice administered with SE 1.8, 1.35 and 0.9 g/kg, respectively). Then some relevant indicators were determined for experimental verification by the forced swim test (FST), the tail suspension test (TST) and open-field test (OFT). Dopamine (DA) concentration in hippocampus and cerebral cortex, IL-2 and corticosterone (CORT) levels in blood, and nuclear factor E2 related factor 2 (Nrf2), kelch-like epichlorohydrin related protein 1 (Keap1), NAD(P) H dehydrogenase [quinone] 1 (NQO1) and heme oxygenase-1 (HO-1) levels in mice were measured by enzyme linked immunosorbent assay (ELISA) and Western blot respectively to explore the possible mechanisms. The "target-disease" network diagram predicted by network pharmacology, showed that the potential target of SE involves a variety of CNS diseases, among which depression accounts for the majority. The experimental results showed that SE (1.8, 1.35 g/kg) significantly decreased the immobility period, compared with the CUMS group in FST and TST in mice after 3-week treatment, while SE exhibited no significant effect on exploratory behavior in OFT in mice. Compared with CUMS group, the SE group (0.9 g/kg) showed significant differences (P<0.05) in DA levels in the hippocampus and cerebral cortex. In addition, compared with CUMS control group, SE (1.8 g/kg) group showed a significant effect on decreasing the activities of CORT (P<0.05), and serum IL-2 level with no statistical significance. Finally, Western blot results showed that compared with the model group, Nrf2, Keap1, NQO1 and HO-1 protein expressions in SE group (1.8 g/kg) were up-regulated (all P<0.01). The SE extract may have an antidepressant effect, which appeared to regulate Nrf2-ARE pathway and increased levels of DA and CORT in the hippocampus and cortex.

Liquiritin Alleviates Depression-Like Behavior in CUMS Mice by Inhibiting Oxidative Stress and NLRP3 Inflammasome in Hippocampus.

Objective Central inflammation is generally accepted to be involved in the pathology of depression. We investigated whether liquiritin exerts antidepressant effects by inhibiting central NLRP3 inflammasomes. Results The behavioral despair model and chronic unpredictable mild stress (CUMS) model in mice were established to evaluate the antidepressant action of liquiritin. In the despair model study, liquiritin (40 mg/kg) administration reduced immobility time in tail suspension test (TST) and forced swimming test (FST) without affecting locomotion activity. In CUMS model study, liquiritin (40 mg/kg, once daily for 4 weeks) significantly increased sucrose consumption and body weight of CUMS mice. The behavioral experiment results showed that liquiritin reduced the immobile time of CUMS mice in TST and FST, respectively, and increased the time spent and open arm entries in the elevated plus-maze (EPM) test. Further, the hippocampal superoxide dismutase (SOD) activity was increased in liquiritin-treated group, while malonaldehyde (MDA) decreased. Additionally, the hippocampal cytokines interleukin-18 (IL-18) and interleukin-1 beta (IL-1β) contents were reduced in the liquiritin-treated group. Further, liquiritin downregulated the expression of NLRP3 in the hippocampus of CUMS mice rather than TLR4. Besides, NLRP3 inflammasome-associated proteins caspase-1 and ASC were also downregulated. However, liquiritin did not alter the thermal stability of NLRP3 in the cellular thermal shift assay (CETSA), suggesting that its inhibition of NLPR3 was not by direct targeting of NLRP3 protein. Conclusions Liquiritin attenuates depression-like behavior of CUMS mice and inhibited cytokines levels triggered by NLRP3 inflammasome, suggesting the antidepressant action is, at least partially, associated with antioxidant stress and inhibition of NLRP3 inflammasome activation.

The modified outer membrane protein Amuc_1100 of Akkermansia muciniphila improves chronic stress-induced anxiety and depression-like behavior in mice.

Akkermansia muciniphila is a next-generation probiotic. The interaction between outer membrane protein Amuc_1100 ofA. muciniphila and toll-like receptor 2 (TLR2) in intestinal epithelial cells influences the level of intestinal 5-hydroxytryptamine (5-HT). Amuc_1100Δ80 is a truncated form of Amuc_1100 lacking the first 80 N-terminal amino acids and has a higher affinity for TLR2 than the wild-type protein. Here, we report that Amuc_1100Δ80 could significantly reduce anxiety and depression-like behavior of mice when they were exposed to chronic unpredictable mild stress (CUMS). The experimental results of the rat insulinoma cell line RIN-14B showed that Amuc_1100Δ80 also induced a significantly higher upregulation of tryptophan hydroxylase 1 (Tph1), a rate-limiting enzyme of intestinal 5-HT synthesis. The imbalance of the gut microflora could be diminished when CUMS mice were fed with Amuc_1100Δ80. These results reveal that Amuc_1100Δ80 could affect the 5-HT level and the downstream 5-HTR1A-CREB-BDNF signal pathway via interacting with TLR2 and by altering the gut microbial composition. In parallel, the downregulation exerted by Amuc_1100Δ80 on the inflammation and hyperactivated HPA axis was closely related to the improvement of depression-like symptoms in CUMS mice. This study not only provides new insights into the antidepressant effect of A. muciniphila and its outer membrane protein Amuc_1100 but also identifies new potential targets and pathways in the gut for future research and the development of antidepressant drugs.

Sortilin deletion in the prefrontal cortex and hippocampus ameliorates depressive-like behaviors in mice via regulating ASM/ceramide signaling.

Major depressive disorder (MDD) is a common psychiatric disorder characterized by persistent mood despondency and loss of motivation. Although numerous hypotheses have been proposed, the possible pathogenesis of MDD remains unclear. Several recent studies show that a classic transporter protein, sortilin, is closely associated with depression. In the present study, we investigated the role of sortilin in MDD using a well-established rodent model of depression. Mice were subjected to chronic unpredictable mild stress (CUMS) for 6 weeks. We showed that the expression levels of sortilin were significantly increased in the prefrontal cortex and hippocampus of CUMS mice. The depressive-like behaviors induced by CUMS were alleviated by specific knockdown of sortilin in the prefrontal cortex and hippocampus. We revealed that sortilin facilitated acid sphingomyelinase (ASM)/ceramide signaling, which activated RhoA/ROCK2 signaling, ultimately causing the transformation of dendritic spine dynamics. Specific overexpression of sortilin in the prefrontal cortex and hippocampus induced depressive-like behaviors, which was mitigated by injection of ASM inhibitor SR33557 (4 µg/μL) into the prefrontal cortex and hippocampus. In conclusion, sortilin knockdown in the prefrontal cortex and hippocampus plays an important role in ameliorating depressive-like behavior induced by CUMS, which is mainly evidenced by decreasing the trafficking of ASM from the trans-Golgi network to the lysosome and reducing the ceramide levels. Our results provide a new insight into the pathology of depression, and demonstrate that sortilin may be a potential therapeutic target for MDD.