Ischemic postconditioning exerts neuroprotective effect through negatively regulating PI3K/Akt2 signaling pathway by microRNA-124.

Ischemic stroke is a serious threat to human life and health, which is often accompanied by cerebral ischemia-reperfusion (I/R) injury in clinic. Ischemic postconditioning (IPostC) is a short period of mild non-fatal ischemia in the early stage of cerebral I/R injury. However, there are few reports about the protective effect of IPostC. In the present study, we investigated the neuroprotective effect of IPostC in a mice model of ischemia induced by the middle cerebral artery occlusion (MCAO). MicroRNA-124(miR-124) is a small RNA highly expressed in the brain. Several studies have shown that miR-124 is significantly decreased in IPostC. Therefore, we hypothesize that IPostC may play an important role by downregulating the expression of miR-124. Mice were treated with cerebral I/R and IPostC treatment on the basis of MCAO. The results showed that IPostC significantly reduced neurobehavioral deficits and decreased brain infarct volume. Moreover, we also found that inhibiting miR-124 effectively reduced neurons/cells apoptosis in vivo and vitro. In addition, western blot analysis of apoptosis-related proteins and PI3K/Akt2 signaling pathway proteins showed that downregulation of miR-124 significantly decreased the expression of Caspase-3 and BAX, and increased the expression of anti-apoptotic protein Bcl-2. Inhibition of miR-124 also increase PI3K/Akt/mTOR signaling pathway, thus inhibiting cell apoptosis and autophagy. However, overexpression of miR-124 weakens the protective effect of IPostC. These observations suggest that IPostC exerts its neuroprotective effect through negatively regulating PI3K/Akt2 signaling pathway by miR-124.

Scutellarin may alleviate cognitive deficits in a mouse model of hypoxia by promoting proliferation and neuronal differentiation of neural stem cells.

OBJECTIVES: Scutellarin, a flavonoid extracted from the medicinal herb Erigeron breviscapus Hand-Mazz, protects neurons from damage and inhibits glial activation. Here we examined whether scutellarin may also protect neurons from hypoxia-induced damage. MATERIALS AND METHODS: Mice were exposed to hypoxia for 7 days and then administered scutellarin (50 mg/kg/d) or vehicle for 30 days Cognitive impairment in the two groups was assessed using the Morris water maze test, cell proliferation in the hippocampus was compared using 5-bromo-2-deoxyuridine (BrdU) immunohistochemistry, and hippocampal levels of nestin and neuronal class III ß-tubulin (Tuj-1) were measured using Western blotting. These results were validated in vitro by treating cultured neural stem cells (NSCs) with scutellarin (30 µM). RESULTS: Treating mice with scutellarin shortened escape times and increased the number of platform crossings, it increased the number of BrdU-positive proliferating cells in the hippocampus, and it up-regulated expression of nestin and Tuj-1. Treating NSC cultures with scutellarin increased the number of proliferating cells and the proportion of cells differentiating into neurons instead of astrocytes. The increase in NSC proliferation was associated with phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, while neuronal differentiation was associated with altered expression of differentiation-related genes. CONCLUSION: Scutellarin may alleviate cognitive impairment in a mouse model of hypoxia by promo-ting proliferation and neuronal differentiation of NSCs.

Neuroprotection induced by post-conditioning following ischemia/reperfusion in mice is associated with altered microRNA expression.

Ischemic preconditioning and ischemic postconditioning (IPostC) represent promising strategies to reduce ischemia-reperfusion (I/R) injury and attenuate the lethal ischemic damage following stroke. However, the mechanism underlying this attenuation remains to be elucidated. It was hypothesized that alterations in microRNA (miRNA) expression in the cerebral cortex and hippocampus of mice following I/R is associated with the functional improvement induced by IPostC. Behavioral changes were assessed in a mouse model of I/R in the absence or presence of IPostC, followed by microarray analyses to investigate the expressional alterations of miRNAs in the cerebral cortex and hippocampus of mice. The results of the present study revealed that IPostC abrogated the neurological impairment and hippocampus­associated cognitive deficits induced by I/R, and upregulated or downregulated the expression levels of numerous miRNAs. Furthermore, the upregulation of miR­19a, and the downregulation of miR­1, let­7f and miR­124 expression levels following IPostC was confirmed utilizing reverse transcription­quantitative polymerase chain reaction. The results of the present study demonstrated that alterations in miRNA expression in the cerebral cortex and hippocampus of mice following I/R was associated with the neuroprotection induced by IPostC.

Spontaneous running wheel improves cognitive functions of mouse associated with miRNA expressional alteration in hippocampus following traumatic brain injury.

Traumatic brain injury (TBI) is an insult to the brain that results in impairments of cognitive and physical functioning. Both of human research and animal studies demonstrate that spontaneous exercise can facilitate neuronal plasticity and improve cognitive function in normal or TBI rodent models. However, the possible mechanisms underlying are still not well known. We postulated that spontaneous running wheel (RW) altered microRNA (miRNA) expressions in hippocampus of mice following TBI, which might be associated with the improvement in cognitive functions. In the present study, acquisition of spatial learning and memory retention was assessed by using the Morris water maze (MWM) test on days 15 post RW exercise. Then, microarray analyses in miRNA files were employed, and the expressional changes of miRNAs in the hippocampus of mice were detected. The results showed that spontaneous RW exercise (i) recovered the hippocampus-related cognitive deficits induced by TBI, (ii) altered hippocampal expressions of miRNAs in both of sham and TBI mice, and (iii) miR-21 or miR-34a was associated with the recovery process. The present results indicated that an epigenetic mechanism might be involved in voluntary exercise-induced cognitive improvement of mice that suffered from TBI.

[Chinese herbal decoction Shiquan Dabu Tang inhibits tumor growth and angiogenesis of metastasis after primary tumor surgical removal in mice].

OBJECTIVE: This study aimed to investigate the effects of Shiquan Dabu Tang (SDT) on growth and angiogenesis of subcutaneously implanted tumors, hepatic metastases, and incision-implanted tumors after surgical removal of primary colon tumor in mice. METHODS: Three experimental models were built after surgical removal of primary colon tumor and the mice were randomly divided into three groups: primary tumor resection (TR) group, primary tumor-preserved (TP) group and SDT group. After resection of the primary tumor and SDT treatment for 10 d, levels of vascular endothelial growth factor (VEGF), angiostatin (AS) and endostatin (ES) were examined by enzyme-linked immunosorbent assay (ELISA); microvascular density (MVD) and cell proliferation of metastasis were detected by streptavidin-peroxidase immunohistochemical staining; tumor cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL) assay. RESULTS: In the subcutaneously implanted tumor model, the average volume of metastases of the SDT group was significantly lower than that of the TR group (P<0.01); the incidence rate of metastases was 50%. In the hepatic metastases model, the average number of hepatic metastases nodules of the SDT group was significantly lower than that of the TR group (P<0.01); the incidence rate of metastases was 40%. In the incision-implanted tumor model, the average volume of metastases of the SDT group was significantly lower than that of the TR group; the incidence rate of metastases was 30%. MVD was significantly inhibited by SDT and Ki67 expression of the SDT group was significantly lower than that of the TR group (P<0.01). TUNEL apoptotic index of tumor of the SDT group was higher than that of the TR group (P<0.01). ELISA showed that the serum VEGF level was significantly decreased and the serum ES level was significantly increased in the SDT group compared with those in the TR group (P<0.01). CONCLUSION: Resection of primary tumor in mice causes imbalance of VEGF, AS and ES, thus promoting angiogenesis and metastasis of tumors. SDT can inhibit growth, angiogenesis and cell proliferation of the metastatic tumor and promote cell apoptosis after surgical removal of the primary tumors.