scholarly journals mTORC1 Signaling Pathway Mediates Chronic Stress-Induced Synapse Loss in the Hippocampus

2021 ◽  
Vol 12 ◽  
Author(s):  
Yu-Fei Luo ◽  
Xiao-Xia Ye ◽  
Ying-Zhao Fang ◽  
Meng-Die Li ◽  
Zhi-Xuan Xia ◽  
...  

Background: The mechanistic target of rapamycin complex 1 (mTORC1) signaling has served as a promising target for therapeutic intervention of major depressive disorder (MDD), but the mTORC1 signaling underlying MDD has not been well elucidated. In the present study, we investigated whether mTORC1 signaling pathway mediates synapse loss induced by chronic stress in the hippocampus.Methods: Chronic restraint stress-induced depression-like behaviors were tested by behavior tests (sucrose preference test, forced swim test and tail suspension test). Synaptic proteins and alternations of phosphorylation levels of mTORC1 signaling-associated molecules were measured using Western blotting. In addition, mRNA changes of immediate early genes (IEGs) and glutamate receptors were measured by RT-PCR. Rapamycin was used to explore the role of mTORC1 signaling in the antidepressant effects of fluoxetine.Results: After successfully establishing the chronic restraint stress paradigm, we observed that the mRNA levels of some IEGs were significantly changed, indicating the activation of neurons and protein synthesis alterations. Then, there was a significant downregulation of glutamate receptors and postsynaptic density protein 95 at protein and mRNA levels. Additionally, synaptic fractionation assay revealed that chronic stress induced synapse loss in the dorsal and ventral hippocampus. Furthermore, these effects were associated with the mTORC1 signaling pathway-mediated protein synthesis, and subsequently the phosphorylation of associated downstream signaling targets was reduced after chronic stress. Finally, we found that intracerebroventricular infusion of rapamycin simulated depression-like behavior and also blocked the antidepressant effects of fluoxetine.Conclusion: Overall, our study suggests that mTORC1 signaling pathway plays a critical role in mediating synapse loss induced by chronic stress, and has part in the behavioral effects of antidepressant treatment.

2021 ◽  
Vol 12 (1) ◽  
pp. 154-163
Author(s):  
Jie Wu ◽  
Cui Liu ◽  
Ling Zhang ◽  
Bing He ◽  
Wei-Ping Shi ◽  
...  

Abstract Background To investigate the effects of chronic restraint stress on cognition and the probable molecular mechanism in mice. Methods In the current work, a restraining tube was used as a way to induce chronic stress in mice. The protein levels were determined with ELISA and western blot. A series of behavior tests, including the Morris water maze, elevated plus maze, open field test, and novel object recognition test, were also performed to examine the anxiety and the ability of learning and memory. Moreover, murine neuroblastoma N2a cells were used to confirm the findings from mice under chronic stress. Results Decreased synaptic functions were impaired in chronic stress with the downregulation of PSD95, GluR-1, the neurotrophic factor BDNF, and immediate-onset genes Arc and Egr. Chronic restraint decreased the histone acetylation level in hippocampal neurons while HDAC2 was increased and was co-localized with glucocorticoid receptors. Moreover, chronic stress inhibited the PI3K/AKT signaling pathway and induced energy metabolism dysfunctions. Conclusion This work examining the elevated levels of HDAC2 in the hippocampus may provide new insights and targets for drug development for treating many neurodegenerative diseases.


2020 ◽  
Vol 18 (11) ◽  
pp. 872-880
Author(s):  
Ying-Li ZHU ◽  
Lin-Yuan WANG ◽  
Dan-Ping ZHAO ◽  
Cheng-Long WANG ◽  
Rui ZHANG ◽  
...  

2018 ◽  
Vol 46 (02) ◽  
pp. 357-387 ◽  
Author(s):  
Dool-Ri Oh ◽  
Yujin Kim ◽  
Eun-Jin Choi ◽  
Myung-A Jung ◽  
Kyo-Nyeo Oh ◽  
...  

The fruit of Vaccinium bracteatum Thunb. (VBF) is commonly known as the oriental blueberry in Korea. The aim of this study was to evaluate the antidepressant-like effects of water VBF extract (VBFW) in a mouse model of chronic restraint stress (CRS) and to identify the underlying mechanisms of its action. The behavioral effects of VBFW were assessed in the forced swim test (FST) and open field test (OFT). The levels of serum corticosterone (CORT), brain monoamines, in addition to the extracellular signal-regulated kinases (ERKs)/protein kinase B (Akt) signaling pathway were evaluated. VBFW treatment significantly reduced the immobility time and increased swimming time in FST without altering the locomotor activity in unstressed mice. Furthermore, CRS mice treated with VBFW exhibited a significantly decreased immobility time in FST and serum CORT, increased locomotor activity in OFT, and enhanced brain monoamine neurotransmitters. Similarly, VBFW significantly upregulated the ERKs/Akt signaling pathway in the hippocampus and PFC. In addition, VBFW may reverse CORT-induced cell death by enhancing cyclic AMP-responsive element-binding protein expression through the up-regulation of ERKs/Akt signaling pathways. In addition, VBFW showed the strong antagonistic effect of the 5-HT[Formula: see text] receptor by inhibiting 5-HT-induced intracellular Ca[Formula: see text] and ERK1/2 phosphorylation. Our study provides evidence that antidepressant-like effects of VBFW might be mediated by the regulation of monoaminergic systems and glucocorticoids, which is possibly associated with neuroprotective effects and antagonism of 5-HT[Formula: see text] receptor.


2020 ◽  
Vol 23 (12) ◽  
pp. 821-836
Author(s):  
Ting-Ting Gao ◽  
Yuan Wang ◽  
Ling Liu ◽  
Jin-Liang Wang ◽  
Ying-Jie Wang ◽  
...  

Abstract Background Depression is one of the most common forms of mental illness and also a leading cause of disability worldwide. Developing novel antidepressant targets beyond the monoaminergic systems is now popular and necessary. LIM kinases, including LIM domain kinase 1 and 2 (LIMK1/2), play a key role in actin and microtubule dynamics through phosphorylating cofilin. Since depression is associated with atrophy of neurons and reduced connectivity, here we speculate that LIMK1/2 may play a role in the pathogenesis of depression. Methods In this study, the chronic unpredictable mild stress (CUMS), chronic restraint stress (CRS), and chronic social defeat stress (CSDS) models of depression, various behavioral tests, stereotactic injection, western blotting, and immunofluorescence methods were adopted. Results CUMS, CRS, and CSDS all significantly enhanced the phosphorylation levels of LIMK1 and LIMK2 in the medial prefrontal cortex (mPFC) but not the hippocampus of mice. Administration of fluoxetine, the most commonly used selective serotonin reuptake inhibitor in clinical practice, fully reversed the effects of CUMS, CRS, and CSDS on LIMK1 and LIMK2 in the mPFC. Moreover, pharmacological inhibition of LIMK1 and LIMK2 in the mPFC by LIMKi 3 infusions notably prevented the pro-depressant effects of CUMS, CRS, and CSDS in mice. Conclusions In summary, these results suggest that LIMK1/2 in the mPFC has a role in chronic stress-induced depressive-like effects in mice and could be a novel pharmacological target for developing antidepressants.


2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Mi Kyoung Seo ◽  
Young Hoon Kim ◽  
Roger S. McIntyre ◽  
Rodrigo B. Mansur ◽  
Yena Lee ◽  
...  

Recent studies have shown that antipsychotic drugs have epigenetic effects. However, the effects of antipsychotic drugs on histone modification remain unclear. Therefore, we investigated the effects of antipsychotic drugs on the epigenetic modification of the BDNF gene in the rat hippocampus. Rats were subjected to chronic restraint stress (6 h/d for 21 d) and then were administered with either olanzapine (2 mg/kg) or haloperidol (1 mg/kg). The levels of histone H3 acetylation and MeCP2 binding at BDNF promoter IV were assessed with chromatin immunoprecipitation assays. The mRNA levels of total BDNF with exon IV, HDAC5, DNMT1, and DNMT3a were assessed with a quantitative RT-PCR procedure. Chronic restraint stress resulted in the downregulation of total and exon IV BDNF mRNA levels and a decrease in histone H3 acetylation and an increase in MeCP2 binding at BDNF promoter IV. Furthermore, there were robust increases in the expression of HDAC5 and DNMTs. Olanzapine administration largely prevented these changes. The administration of haloperidol had no effect. These findings suggest that the antipsychotic drug olanzapine induced histone modification of BDNF gene expression in the hippocampus and that these epigenetic alterations may represent one of the mechanisms underlying the actions of antipsychotic drugs.


2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Yu Wang ◽  
Huili Jiang ◽  
Hong Meng ◽  
Jing Li ◽  
XinJing Yang ◽  
...  

Major depressive disorder (MDD) is a chronic disease that adversely affects mood and cognition. In this study, we randomly divided the rats into control group (C), model group (M), fluoxetine group (F), and acupuncture group (A), used open-field test to ascertain whether acupuncture affects chronic restraint stress (CRS) induced depression-like behaviors of rats, and explored the antidepressant mechanism of acupuncture at the molecular level of transcriptome in the frontal cortex of CRS rats by RNA-sequencing (RNA-seq). According to differentially expressed genes (DEG) analysis, we identified 134, 46, and 89 response genes differentially expressed in C versus M, F versus M, and A versus M, respectively. Through Gene Ontology (GO) term enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, we identified the gene sets involved in extracellular space, inflammatory response, Toll-like receptor signaling pathway, chemokine signaling pathway, and TNF signaling pathway. In this study, RNA-seq technology was used to investigate the frontal cortex genome-wide transcriptomes in depression rats under CRS, which suggested that the antidepressant effect of acupuncture is effective and has a multitarget characteristic, which may be related to amino acid metabolism and inflammatory pathways, especially the Toll-like receptor signaling pathway, TNF signaling pathway, and NF-kappa B signaling pathway.


2021 ◽  
Author(s):  
Qian Zhai ◽  
Yanpeng Zhang ◽  
Shuwen Tan ◽  
Jianyu Sun ◽  
Mao Ye ◽  
...  

Abstract Background The STING-TBK1-IRF3 signaling pathway involves in modulating host innate immunity, however, the potential role of STING signaling pathway in chronic restraint stress model has not been determined. The aim of this study is to explore the underlying role of STING signaling pathway in regulating neuroinflammation, as well as to evaluate the therapeutic potential of STING agonist during chronic restraint stress. Methods C57BL/6 mice were subject to 14-day intermittent restraint stress. Sucrose preference, elevated plus maze and tail suspension tests were measured in chronic restraint stress mice. Expression levels of proinflammatory cytokines were tested by QT-PCR and Luminex cytokine assays. The fluorescence-labeled latex beads, flow cytometry and CD68 positive cell counts were utilized to evaluate phagocytic abilities of microglia. Then, the ability of intracerebroventricular injection of STING agonist, 2’3-cGAMP, to reverse the depression-like behaviors and inflammatory cytokines was examined. Results We found that the expression levels of STING, p-TBK1, and p-IRF3 were remarkably decreased in chronic restraint stress mice, which was associated with decreased IFN-β secretion. Moreover, the STING agonist, 2’3-cGAMP, significantly alleviated the neuroinflammation and ameliorated depression-like behavior which depends on the functional STING activation. Furthermore, 2’3-cGAMP promoted microglia phagocytosis through cGAMP-STING-dependent IFN-β release, which was essential for recovery from neuroinflammation during chronic restraint stress. Conclusions These findings demonstrate that STING signaling pathway is a critical mediator in regulating microglia phagocytosis and may serve as a novel therapeutic target for chronic stress-related psychiatric diseases.


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