Objective To review the possible mechanisms of the mammal ian target of rapamycin (mTOR) in theneuronal restoration process after nervous system injury. Methods The related l iterature on mTOR in the restoration ofnervous system injury was extensively reviewed and comprehensively analyzed. Results mTOR can integrate signals fromextracellular stress and then plays a critical role in the regulation of various cell biological processes, thus contributes to therestoration of nervous system injury. Conclusion Regulating the activity of mTOR signaling pathway in different aspects cancontribute to the restoration of nervous system injury via different mechanisms, especially in the stress-induced brain injury.mTOR may be a potential target for neuronal restoration mechanism after nervous system injury.
Objective To review the role of integrin in nervous system injury and its repair, and to analyze the possible mechanisms. Methods Recent l iterature concerning integrin and its role in nervous system injury was reviewed and analyzed. Results Integrin and its related signall ing pathway were involved in nervous system injury, especially hypoxicischemic nervous injury, and their repair processes. Conclusion Intervention of integrin signall ing pathway would be a potential strategy to treat nervous system injury, especially hypoxic-ischemic nervous injury.
Objective To review the research process of telomerase reverse transcriptase (TERT) in the restoration of neurological diseases. Methods The related l iterature on TERT in the restoration of neurological diseases was extensively reviewed and comprehensively analyzed. Results TERT was the significant component of telomerase and the critical regulator of telomerase activity. It played an important role in the pathomechanism of neurological diseases including tumors,neurodevelopmental deficits, and nerve injury. TERT was becoming a research focus in the reparative therapy of neurological diseases. Conclusion TERT has manifested its great academic significance and appl ication prospects in the reparative therapy of neurological diseases, which deserves a further investigation.
To review the role of hypoxia inducible factor 1α (HIF-1α) in hypoxic-ischemic injury and its repair, and to analyze the possible mechanisms. Methods Recent l iterature on HIF-1α and its role in hypoxic-ischemic injury was reviewed and analyzed. Results HIF-1α was involved in the hypoxic-ischemic injury of various organs or tissues and their repair processes. Conclusion HIF-1α has a potential to treat common cl inical hypoxic-ischemic injuries and has a promisingfuture for appl ication.
Objective To investigate the expression of hypoxia inducible factor 1α (HIF-1α) protein and the activation of phosphoinositid 3-kinase/Akt (PI3K/Akt) signal ing pathway in neurons under hypoxia ischemia condition,and to elucidate the role of PI3K/Akt on HIF-1α regulation in the developing neurons after hypoxia ischemia brain damage(HIBD). Methods Fifty-six SD rats aged 10 days were randomly divided into normal control group (n=12), sham operationgroup (n=12), experimental group (n=24), wortmannin treated group (n=4) and DMSO/PBS treated group (n=4). In theexperimental group, the rats were anesthetized with ethylether. The right common carotid artery was exposed and l igated. Then, they were exposed to hypoxia in a normobaric chamber filled with 8% oxygen and 92% nitrogen for 2.5 hours. In the sham control group, the right common carotid artery was exposed but was not l igated or exposed hypoxia. In the normal control group, the rats recevied no further processing. For wortmannin treated group and DMSO/PBS treated group, the rats received intraventricular injection of wortmannin or DMSO/PBS 30 minutes before hypoxia ischemia. The brain tissues were harvested from the rats in the normal control, sham operation and experimental groups at 4, 8 and 24 hours after hypoxia ischemia, but in the wortmannin and DMSO/PBS treated groups only at 4 hours. The HIF-1α protein expression and Akt protein expression were detected with immunohistochemistry method. HIF-1α, Akt and p-Akt protein expression were measured by Western blot analysis. Results In the experimental group, the HIF-1α expression was significantly increased at 4 hours after operation, reached the peak level at 8 hours, and began to decrease at 24 hours. The p-Akt protein was significantly increased at 4 hours, and began to decrease at 8 hours. However, the expression levels of HIF-1α and p-Akt protein in the normal control group were extremely low at each time point. So, the expression levels of HIF-1α in the experimental group was significantly higher than that in the normal control groups (P lt; 0.01), the expression of p-Akt protein in the experimental group at 4 and 8 hours was significant higher than that in the normal control group (P lt; 0.05). The change of Akt protein in the experimental group was not time-dependent, and no significant difference was evident when compared with that of the normal control group (P gt; 0.05). Using wortmannin, the PI3K/Akt specific inhibitor, HIF-1α protein expression was significantly decreased when compared with the DMSO/PBS treated group and experimental group (P lt; 0.01). Conclusion These results suggested that the HIBD of neonatal rats may activate PI3K/Akt signal ing pathway and further induce the expression of HIF-1α, indicating PI3K/Akt signal ing pathway and HIF-1α could be a potential target for treatment of neonatal HIBD.
Objective To investigate the expression of telomerase reverse transcriptase (TERT) and cell apoptosis in neonatal rats with hypoxia ischemia brain damage (HIBD). Methods A total of 42 7-day-old SD rats (12-18 g, male or female) were randomly allocated into sham-operation group (n=6) and hypoxia-ischemia (HI) group (n=36). In HI group, the rats were anesthetized with ethylether. The right common carotid artery (CCA) was exposed and permanently l igated with a 7-0silk suture through a midl ine cervical incision. A duration of 2.5 hours of hypoxia (8%O2 / 92%N2) was used to produce HIBD model. For sham-operation group, the CCA was exposed without l igation or hypoxia. The brain tissues were harvested at 4, 8, 12, 24, 48, and 72 hours after completion of an HI insult. The expressions of TERT and CC3 were detected by immunohistochemical staining. The apoptosis cells were detected with TUNEL staining method. Results The expression of TERT was increased at 4 hours after HI injury, significantly increased at 24-48 hours and then decreased at 72 hours. The expression of CC3 was increased at 4 hours after HI injury, significantly increased at 24 hours and still maintained high expression at 48 hours and 72 hours. However, in the sham-operation group, both the expressions of TERT and CC3 were extremely low. The expression of TERT and CC3 were higher in the HI group than in the sham-operation group at different time points, and the differences were significant (P lt; 0.05). The TUNEL staining showed that the positive cells in hippocampus and cortical areas were increased at 4 hours after HI injury, significantly increased at 24-48 hours and maintained a high level at 72 hours. However, there was few positive cells in the sham-operation group. There were significant differences between the HI group and the sham-operation group at different time points (P lt; 0.05). Conclusion TERT could be induced by HI in neonatal rats, and might have a protective role in regulating the cell apoptosis in the neonatal HIBD.
Objective Telomerase reverse transcriptase (TERT) is the key factor to determine cell growth and l ifespan. Meanwhile, it is tightly related to resistance of cell to stress and apoptosis. However, up till now l ittle is known about the role TERT plays in nervous system. To investigate the effect of conditioned medium from astrocytes (AS) transfected with TERT on neurons subjected to hypoxia-ischemia-reperfusion (HI-RP) through construction of in vitro HI-RP model of neurons. Methods An eukaryote expression plasmids containing rat full length TERT gene was constructed as pcDNA3-TERT. Twenty newborn rats at age of 3 days were sacrificed and their cerebral cortex were collected for isolation and cultivationof AS. Then AS were transfected with pcDNA3-TERT through l iposomes mediation, and positive clones were selected by G418 and expanded for continuous culture to establ ish the plamid pcDNA3-TERT transfection group. Meanwhile, the empty plasmid pcDNA3 transfection group and the non-transfection group were establ ished as control. The expression of gl ial fibrillary acidic protein (GFAP), which was the specific marker of the AS, was detected by immunocytochemistry, as well as the expression of TERT. Astrocyte conditioned medium (ACM) of the plamid pcDNA3-TERT transfection group was collected as TERT-ACM, while the ACM of the empty plasmid pcDNA3 transfection group and the non-transfection group were collected respectively as p-ACM and ACM. Next, 60 rats at age of 1 day were sacrificed and their cerebral cortex were collected for isolation and cultivation of neurons. The neurons were randomly divided into experimental group and normal group, the experimental group were further divided into 4 groups including control group, ACM group, p-ACM group, and TERT-ACM group. The neurons of control group were subjected to HI damage in serum-free DMEM, and the neurons of ACM group, p-ACM group, and TERTACM group were subjected to HI damage in different medium which contained ACM, p-ACM, and TERT-ACM, respectively. After duration of HI for 3 hours under the environment with 5%CO2, 1%O2, and 94%N2; the neurons of experimental groups were placed in CO2 incubator to imitate RP for 3, 6, 18, 24, and 36 hours in vitro. The neurons of normal group were not subjected to HI and RP treatment. During the treatment of HI-RP, the survival ratio of neurons was detected by means of MTT, the lactate dehydrogenase (LDH) activity of neuron medium with LDH detection kit, and the neuronal apoptosis by means of TUNEL. Results The percentages of GFAP positive cells were 98%, 99%, and 98% in non-transfection group, plasmid pcDNA3-TERT transfection group, and plasmid pcDNA3 transfection group, respectively. There was no expression of TERT in no-transfection group and plasmid pcDNA3 transfection group, and the percentage of TERT positive cells in plasmid pcDNA3- TERT transfection group was 98%. Compared with normal group, the survival ratio of ......（余见正文）