To study the effects of oestrogcn on ischemia-induced neurogenesis in the hippocampal dentate gyms, thirty-two adult male rats were randomly divided into four groups： the control surgery group with eestrogen administ...To study the effects of oestrogcn on ischemia-induced neurogenesis in the hippocampal dentate gyms, thirty-two adult male rats were randomly divided into four groups： the control surgery group with eestrogen administration （SE）, the control surgery group with normal saline administration （SN）, the middle cerebral artery occlusion （MCAO） group with oestrogen administration （ME） and the MCAO group with normal saline administration （MN）. The MCAO rats were occluded for 90 rain by an intraluminal filament and then recirculated. After 1, 3, 12, 24 and 28 h of MCAO, the rats of the four groups were killed to investigate the infarct volume, apoptosis and neurogenesis. The cerebral infarct volume in the ME group was significantly smaller than that of the MN group （P 〈 0.05）. No significant cell loss was seen in the dentate gyms. Cerebral ischemia led to increased neurogenosis, which is independent of cell death in the ipsilateral dentate gyrus（P 〈 0.05）. BrdU-pesitive cells in the ipsilateral dentate gyms of the ME group were significantly increased when compared with those of the MN group（P 〈 0.05）. In the SE group, BrdU-positive cells in both the ipsilateral and contralateral dentate gyms, were increased when compared with those of the SN group （ P 〈 0.05 ）. We concluded that ocstregen plays an important role in neurogenesis, which is independent of ischemia-induced by MCAO in the hippocampal dentate gyms of rats.展开更多
Spiral wave could be observed in the excitable media, the neurons are often excitable within appropriateparameters. The appearance and formation of spiral wave in the cardiac tissue is linked to monomorphic ventricula...Spiral wave could be observed in the excitable media, the neurons are often excitable within appropriateparameters. The appearance and formation of spiral wave in the cardiac tissue is linked to monomorphic ventriculartachycardia that can denervate into polymorphic tachycardia and ventricular fibrillation. The neuronal system oftenconsists of a large number of neurons with complex connections. In this paper, we theoretically study the transitionfrom spiral wave to spiral turbulence and homogeneous state (death of spiral wave) in two-dimensional array of theHindmarsh-Rose neuron with completely nearest-neighbor connections. In our numerical studies, a stable rotating spiralwave is developed and selected as the initial state, then the bifurcation parameters are changed to different values toobserve the transition from spiral wave to homogeneous state, breakup of spiral wave and weak change of spiral wave,respectively. A statistical factor of synchronization is defined with the mean field theory to analyze the transition fromspiral wave to other spatial states, and the snapshots of the membrane potentials of all neurons and time series of meanmembrane potentials of all neurons are also plotted to discuss the change of spiral wave. It is found that the sharpchanging points in the curve for factor of synchronization vs. bifurcation parameter indicate sudden transition fromspiral wave to other states. And the results are independent of the number of neurons we used.展开更多
Upon activation, tumor necrosis factor alpha （TNF-α） receptor can engage apoptotic or survival pathways. Inhibition of macromolecular synthesis is known to sensitize cells to TNF-α-induced cell death. It is believ...Upon activation, tumor necrosis factor alpha （TNF-α） receptor can engage apoptotic or survival pathways. Inhibition of macromolecular synthesis is known to sensitize cells to TNF-α-induced cell death. It is believed that this sensitization is due to the transcriptional blockade of genes regulated by NF-κB. Nevertheless, such evidence has remained elusive in the nervous system. Here, we show that TNF-α cannot normally induce apoptosis in PC12 cells or cortical neurons. However, cells treated with Actinomycin D （ActD） become susceptible to TNF-α-induced cell death through the activation of caspase-8, generation of tBid and activation of caspase-9 and -3. Analysis of several proteins involved in TNF-α receptor signaling showed no significant downregulation of NF-κB target genes, such as IAPs or FLIP, under such conditions. However, Bcl-XL protein levels, but not those of Bcl-2, Bax and Bak, are reduced by ActD or TNF-α/ ActD treatments. Moreover, Bcl-xL overexpression fully protects cells against TNF-α/ActD-induced cell death. When endogenous levels of Bcl-XL are specifically downregulated by lentiviral-based RNAi, cells no longer require ActD to be sensitive to TNF-α-triggered apoptosis. Furthermore, Bcl-xL downregulation does not affect TNF-α-mediated NF-κB activation. Altogether, our results demonstrate that Bcl-XL, and not Bci-2, FLIP or IAPs, acts as the endogenous regulator of neuronal resistance/sensitivity to TNF-α-induced apoptosis in an NF-κB-independent manner.展开更多
The development of spiral wave in a two-dimensional square array due to partial ion channel block （Potas- sium, Sodium） is investigated, the dynamics of the node is described by Hodgkin-Huxley neuron and these neuro...The development of spiral wave in a two-dimensional square array due to partial ion channel block （Potas- sium, Sodium） is investigated, the dynamics of the node is described by Hodgkin-Huxley neuron and these neurons are coupled with nearest neig1 bor connection. The parameter ratio xNa （and xK）, which defines the ratio of working ion channel number of sodium （potassium） to the total ion channel number of sodium （and potassium）, is used to measure the shift conductance induced by channel block. The distribution of statistical variable R in the two-parameter phase space （parameter ratio vs. poisoning area） is extensively calculated to mark the parameter region for transition of spiral wave induced by partial ion channel block, the area with smaller factors of synchronization R is associated the parameter region that spiral wave keeps Mive and robust to the channel poisoning. SpirM wave keeps alive when the poisoned area （potassium or sodium） and degree of intoxication are small, distinct transition （death, several spiral waves coexist or multi-axm spiral wave emergence） occurs under moderate ratio XNa （and XK） when the size of blocked area exceeds certain thresholds. Breakup of spiral wave occurs and multi-axm of spiral waves are observed when the channel noise is considered.展开更多
文摘To study the effects of oestrogcn on ischemia-induced neurogenesis in the hippocampal dentate gyms, thirty-two adult male rats were randomly divided into four groups： the control surgery group with eestrogen administration （SE）, the control surgery group with normal saline administration （SN）, the middle cerebral artery occlusion （MCAO） group with oestrogen administration （ME） and the MCAO group with normal saline administration （MN）. The MCAO rats were occluded for 90 rain by an intraluminal filament and then recirculated. After 1, 3, 12, 24 and 28 h of MCAO, the rats of the four groups were killed to investigate the infarct volume, apoptosis and neurogenesis. The cerebral infarct volume in the ME group was significantly smaller than that of the MN group （P 〈 0.05）. No significant cell loss was seen in the dentate gyms. Cerebral ischemia led to increased neurogenosis, which is independent of cell death in the ipsilateral dentate gyrus（P 〈 0.05）. BrdU-pesitive cells in the ipsilateral dentate gyms of the ME group were significantly increased when compared with those of the MN group（P 〈 0.05）. In the SE group, BrdU-positive cells in both the ipsilateral and contralateral dentate gyms, were increased when compared with those of the SN group （ P 〈 0.05 ）. We concluded that ocstregen plays an important role in neurogenesis, which is independent of ischemia-induced by MCAO in the hippocampal dentate gyms of rats.
基金Supported by National Nature Science of Foundation of China under Grant Nos. 10747005, 10847140the Natural Science of Lanzhou University of Technology under Grant No. Q200706
文摘Spiral wave could be observed in the excitable media, the neurons are often excitable within appropriateparameters. The appearance and formation of spiral wave in the cardiac tissue is linked to monomorphic ventriculartachycardia that can denervate into polymorphic tachycardia and ventricular fibrillation. The neuronal system oftenconsists of a large number of neurons with complex connections. In this paper, we theoretically study the transitionfrom spiral wave to spiral turbulence and homogeneous state (death of spiral wave) in two-dimensional array of theHindmarsh-Rose neuron with completely nearest-neighbor connections. In our numerical studies, a stable rotating spiralwave is developed and selected as the initial state, then the bifurcation parameters are changed to different values toobserve the transition from spiral wave to homogeneous state, breakup of spiral wave and weak change of spiral wave,respectively. A statistical factor of synchronization is defined with the mean field theory to analyze the transition fromspiral wave to other spatial states, and the snapshots of the membrane potentials of all neurons and time series of meanmembrane potentials of all neurons are also plotted to discuss the change of spiral wave. It is found that the sharpchanging points in the curve for factor of synchronization vs. bifurcation parameter indicate sudden transition fromspiral wave to other states. And the results are independent of the number of neurons we used.
文摘Upon activation, tumor necrosis factor alpha （TNF-α） receptor can engage apoptotic or survival pathways. Inhibition of macromolecular synthesis is known to sensitize cells to TNF-α-induced cell death. It is believed that this sensitization is due to the transcriptional blockade of genes regulated by NF-κB. Nevertheless, such evidence has remained elusive in the nervous system. Here, we show that TNF-α cannot normally induce apoptosis in PC12 cells or cortical neurons. However, cells treated with Actinomycin D （ActD） become susceptible to TNF-α-induced cell death through the activation of caspase-8, generation of tBid and activation of caspase-9 and -3. Analysis of several proteins involved in TNF-α receptor signaling showed no significant downregulation of NF-κB target genes, such as IAPs or FLIP, under such conditions. However, Bcl-XL protein levels, but not those of Bcl-2, Bax and Bak, are reduced by ActD or TNF-α/ ActD treatments. Moreover, Bcl-xL overexpression fully protects cells against TNF-α/ActD-induced cell death. When endogenous levels of Bcl-XL are specifically downregulated by lentiviral-based RNAi, cells no longer require ActD to be sensitive to TNF-α-triggered apoptosis. Furthermore, Bcl-xL downregulation does not affect TNF-α-mediated NF-κB activation. Altogether, our results demonstrate that Bcl-XL, and not Bci-2, FLIP or IAPs, acts as the endogenous regulator of neuronal resistance/sensitivity to TNF-α-induced apoptosis in an NF-κB-independent manner.
基金Supported by the National Natural Science Foundation of China under Grant No. 11265008
文摘The development of spiral wave in a two-dimensional square array due to partial ion channel block （Potas- sium, Sodium） is investigated, the dynamics of the node is described by Hodgkin-Huxley neuron and these neurons are coupled with nearest neig1 bor connection. The parameter ratio xNa （and xK）, which defines the ratio of working ion channel number of sodium （potassium） to the total ion channel number of sodium （and potassium）, is used to measure the shift conductance induced by channel block. The distribution of statistical variable R in the two-parameter phase space （parameter ratio vs. poisoning area） is extensively calculated to mark the parameter region for transition of spiral wave induced by partial ion channel block, the area with smaller factors of synchronization R is associated the parameter region that spiral wave keeps Mive and robust to the channel poisoning. SpirM wave keeps alive when the poisoned area （potassium or sodium） and degree of intoxication are small, distinct transition （death, several spiral waves coexist or multi-axm spiral wave emergence） occurs under moderate ratio XNa （and XK） when the size of blocked area exceeds certain thresholds. Breakup of spiral wave occurs and multi-axm of spiral waves are observed when the channel noise is considered.
