Effects of Chronic Restraint Stress on Apoptosis of Amygdala Cells in Rats.

OBJECTIVES: To explore the damage effects of chronic restraint stress (CRS) on amygdala cells through the rat CRS model. METHODS: The rat CRS model was established, and the changes in body weight and adrenal mass in control group and CRS group were monitored at 1 d, 7 d, 14 d and 21 d. The behavior changes were evaluated by the percentage of retention time of open arms and open arm entries using the elevated plus maze (EPM). ELISA was used to detect the concentrations of rat's corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and cortisol. The changes of expression of glucocorticoid receptor (GR) and glial fibrillary acidic protein (GFAP) in amygdala were determined by immunohistochemistry and Western blotting. Ultrastructure changes of glial cell were observed by transmission electron microscopy. The apoptosis rate of amygdala was measured by flow cytometry. RESULTS: Compared with the control group at the same time points, body weight of CRS 1 d, 7 d, 14 d and 21 d groups increased slowly, but adrenal mass increased significantly; the serum level of CRH, cortisol and ACTH increased significantly at 7 d, 14 d and 21 d respectively; the expression of GR in amygdala was increased while that of GFAP was decreased; EPM test suggested that the percentage of retention time of open arms and open arm entries decreased significantly after 14 d. The CRS group showed different degrees of glial cell damage in amygdala, and the apoptosis rate of glial cell was significantly increased in 21 d group. CONCLUSIONS: This study successfully established a CRS model in rats, and anxiety-like behavioral changes in model rats may be caused by apoptosis of amygdala astrocytes.

Piezo1 activation facilitates ovarian cancer metastasis via Hippo/YAP signaling axis.

Ovarian cancer (OC) is a highly malignant cancer with great metastatic potential. Here we aimed to investigate the role of Piezo1, a gene related to the mechanical environment of the tumor, in promoting the metastasis of OC. We performed Piezo1 knockdown in A-1847 cells using small hairpin RNAs, and the cells were inoculated subcutaneously in nude mice. Piezo1 knockdown decreased the tumor growth rate of OC tumor xenografts in mice and reduced cell migration in vitro. Metastasis in the lung was also attenuated after Piezo1 knockdown as revealed by HE staining of the lung tissues, which was concomitant with downregulation of E-Cadherin and vimentin and upregulation of N-Cadherin analyzed using western blot analysis, suggesting suppressed epithelial-to-mesenchymal transition. Migration of Piezo1-knockdown cells was also analyzed for their migratory capabilities using the scratch assay. We also analyzed the key proteins in the Hippo/YAP signaling pathway using western blot after treating A-1847 and 3AO cells with a Piezo1 inducer, Yoda1. Piezo1 inducer Yoda1 activated Hippo/YAP signal in OC cells. In conclusion, Piezo1 is overexpressed in OC tissues and contributes to OC tumor growth and metastasis. Suppression of Piezo1 is a potential therapeutic strategy for OC.

Piezo type mechanosensitive ion channel component 1 facilitates gastric cancer omentum metastasis.

The peritoneum, especially the omentum, is a common site for gastric cancer (GC) metastasis. Our aim was to expound the role and mechanisms of Piezo1 on GC omentum metastasis. A series of functional assays were performed to examine cell proliferation, clone formation, apoptosis, Ca2+ influx, mitochondrial membrane potential (MMP) and migration after overexpression or knockdown of Piezo1. A GC peritoneal implantation and metastasis model was conducted. After infection by si-Piezo1, the number and growth of tumours were observed in abdominal cavity. Fibre and angiogenesis were tested in metastatic tumour tissues. Piezo1 had higher expression in GC tissues with omentum metastasis and metastatic lymph node tissues than in GC tissues among 110 patients. High Piezo1 expression was associated with lymph metastasis, TNM and distant metastasis. Overexpressed Piezo1 facilitated cell proliferation and suppressed cell apoptosis in GC cells. Moreover, Ca2+ influx was elevated after up-regulation of Piezo1. Piezo1 promoted cell migration and Calpain1/2 expression via up-regulation of HIF-1α in GC cells. In vivo, Piezo1 knockdown significantly inhibited peritoneal metastasis of GC cells and blocked EMT process and angiogenesis. Our findings suggested that Piezo1 is a key component during GC omentum metastasis, which could be related to up-regulation of HIF-1α.

The Regulatory Mechanism and Biological Significance of Mitochondrial Calcium Uniporter in the Migration, Invasion, Angiogenesis and Growth of Gastric Cancer.

OBJECTIVE: Increasing evidences suggest that mitochondrial calcium uniporter (MCU), a selective channel responsible for mitochondrial Ca2+ uptake, is involved in the progression of several cancers. In this study, we aimed to observe the clinical implications and biological functions of MCU in gastric cancer. METHODS: The expression of MCU in 90 pairs of gastric cancer tissues and adjacent normal tissues was examined using immunohistochemistry and correlation between MCU expression and clinical features was analyzed. After construction of stable MCU knockdown or overexpression gastric cancer cells, mitochondrial membrane potential (MMP), wound healing and transwell assays were performed to examine MMP levels, migration and invasion. Subcutaneous xenograft tumors induced by gastric cancer cells transfected with MCU siRNAs or controls were constructed. Immunofluorescence was used to detect CD34 expression. Western blot was used to detect the expression of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), epithelial-mesenchymal transition (EMT)-related proteins. RESULTS: MCU had a higher expression in gastric cancer tissues than normal tissues. Compared to gastric cancer tissues, its expression was significantly higher after omental metastasis. MCU expression was significantly correlated with depth of invasion (p=0.048), lymph metastasis (p=0.027), TNM stage (p=0.036) and distant metastasis (p=0.029). Patients with high MCU expression indicated a worse prognosis than those with its low expression (p=0.0098). MCU significantly increased the MMP levels of gastric cancer cells. Wound healing and transwell assay results showed that MCU promoted migration and invasion of gastric cancer cells. In vivo, MCU knockdown significantly inhibited tumor growth and angiogenesis. Both in vitro and in vivo, silencing MCU suppressed the expression of HIF-1α and VEGF as well as activity of EMT processes. CONCLUSION: Our findings suggested that highly expressed MCU could promote migration, invasion, angiogenesis and growth of gastric cancer, which could become a potential therapeutic marker for gastric cancer.

RU486 Reverses Emotional Disorders by Influencing Astrocytes and Endoplasmic Reticulum Stress in Chronic Restraint Stress Challenged Rats.

AIMS: To investigate the effect of RU486 (mifepristone) on emotional disorders in chronic restraint stress-induced rats and to explore the mechanisms of that phenomenon. METHODS: For this purpose, 80 healthy male Sprague Dawley rats were randomly divided into four groups: the normal group (Con group, The Con group members received no treatment, eating and drinking freely), the chronic restraint stress group (CRS group, normal Sprague Dawley rats treated with chronic restraint stress, 6 h/day for 21days), the propylene glycol group (CRS+propylene glycol) and the RU486 group (CRS+RU486). RU486 or propylene glycol was administered 30 mins before each CRS procedure. Twenty-four hours after CRS exposure, we investigated the effects of CRS on the anxiety-like behavior using an elevated plus-maze (EPM). To explore the mechanisms of RU486 on anxiety, we measured the expression of glial fibrillary acid protein (GFAP) and ß-subunit of S100 (S100ß) via immunohistochemistry and western blot analysis. Apoptosis was demonstrated by flow cytometry. In addition, endoplasmic reticulum (ER) stress markers, glucose regulated protein 78 (GRP78), C/EBP homologous protein (CHOP) and Cysteine aspartic acid specific protease-12 (Caspase-12), were detected by western blot analysis. RESULTS: Compared to the control group, rats in the CRS and propylene glycol group showed decreased exploratory behavior on the open arms during EPM testing, and these reductions were accompanied by significantly reduced GFAP and S100ß expression, increased apoptosis and GRP78, CHOP, and caspase-12 expression in the amygdala. However, RU486 increases the exploratory behavior and reverses the changes of GFAP, S100ß, GRP78, CHOP, and caspase-12 and protects cells against apoptosis. CONCLUSIONS: Taken together, these data suggest that exposure to chronic restraint stress decreases the number of astrocytes and induces apoptosis and ER stress in the amygdala, which are possible causes for psychiatric disorders. RU486 can significantly ameliorate abnormal behaviors in CRS-induced anxiety model rats. The protective effects of RU486 could be attributed to its anti-ER stress, anti-apoptosis and astrocyte increasing effects.

Secondary damage caused by CD11b+ microglia following diffuse axonal injury in rats.

BACKGROUND: Diffuse axonal injury (DAI) is one of the most common and important pathologic features of human traumatic brain injury, accounting for high mortality and the development of persistent posttraumatic neurologic sequelae. Secondary damage resulting, e.g., from mass compressive effects through edema or inflammation can exacerbate morphologic changes in injured axons. METHODS: In this study, DAI was induced in Sprague-Dawley rats by subjecting the animals to a midline closed-skull strike. Experimental rats and control animals subjected to sham operation were killed at 0 hour, 1 hour, 3 hour, 6 hour, 12 hour, 24 hour, 72 hour, 5 days, or 7 days later. Brains were harvested and paraffin-embedded sections of brain tissue (5 µm thick) were processed for hematoxylin and eosin staining, Bielschowsky silver staining, cresyl violet staining of Nissl bodies, Weil staining of myelin sheaths, or TUNEL assay to verify neuronal changes. Immunocytochemistry was used to examine the expression of [beta]-amyloid precursor protein, CD11b, and interleukin (IL)-6. RESULTS: CD11b/IL-6 expression was higher at 6 hour and peaked at 12 hour after injury. Pathologic changes in neurons were greater at 24 and 48 hour after injury. The results indicate that DAI can induce activation of microglia to express IL-6 in the early stages after injury. CONCLUSIONS: This suggests that microglia play an important role in secondary pathologic changes in brain tissue that are mediated, at least in part, by IL-6.