Temporal and spacial changes of BrdU immunoreactivity in amygdala kindling development

Physical exercise promotes proliferation and differentiation of endogenous neural stem cells via ERK in rats with cerebral infarction

Physical exercise is beneficial for the functional recovery of neurons after stroke. It has been suggested that exercise regulates proliferation and differentiation of endogenous neural stem cells (NSCs); however, the underlying molecular mechanisms are still largely unknown. In the present study, the aim was to investigate whether physical exercise activates the extracellular signal-regulated kinase (ERK) signaling pathway to promote proliferation and differentiation of NSCs in rats with cerebral infarction, thereby improving neurological function. Following middle cerebral artery occlusion, rats underwent physical exercise and neurological behavior was analyzed at various time points. Immunofluorescence staining was performed to detect proliferation and differentiation of NSCs, and western blotting was used to analyze cyclin-dependent kinase 4 (CDK4), Cyclin D1, retinoblastoma protein (p-Rb), P-16, phosphorylated (p)-ERK1/2 and c-Fos expression. The results indicated that physical exercise promoted proliferation and differentiation of NSCs, and led to improved neural function. In addition, the expression levels of CDK4, Cyclin D1, p-Rb, p-ERK1/2 and c-Fos were upregulated, whereas the expression of P-16 was downregulated following exercise. U0126, an inhibitor of ERK signaling, reversed the beneficial effects of exercise. Therefore, it may be hypothesized that physical exercise enhances proliferation and differentiation of endogenous NSCs in the hippocampus of rats with cerebral infarction via the ERK signaling pathway.

Cytogenesis in the adult rat dentate gyrus is increased following kindled seizures but is unaltered in pharmacological models of absence seizures

The production of new neurons continues throughout adulthood in the dentate gyrus of the hippocampal formation, and is believed to play a role in hippocampus-dependent learning and memory. Seizure-induced changes in adult neurogenesis have been examined primarily in convulsive rodent seizure models, but not in models of nonconvulsive absence seizures. This study examined progenitor cell proliferation in the gamma-hydroxybutyrate (GHB) model of typical absence seizures and the AY-9944 model of atypical absence seizures, and compared these results with changes seen in the rat amygdala kindling model. Kindled subjects were found to have 189% more proliferating cells than sham-kindled control subjects, whereas no significant difference was found between the GHB or AY-9944 model and control subjects. These results suggest that changes in adult neurogenesis in models of absence seizures do not occur, and that seizure-induced enhancement of neurogenesis could depend on the characteristics of the seizure discharge.

Regional expression of the radial glial marker vimentin at different stages of the kindling process

The classical view of the function of radial glia in brain development is a supporting function guiding radial neural migration. However, recent evidence indicates that they may play key roles in neurogenesis and gliogenesis, as ubiquitous precursors that generate neurons and glia. Although we previously reported the emergence of radial glia after spinal cord injury in adult rats, their precise function in this process is still unknown. In the present study, we examined emergence of radial glia in rat brain during progression of kindling, by performing immunohistochemical staining for vimentin which is a specific marker of radial glia. Vimentin immunoreactivity was found to be highest at clonus 3 and then decreased at clonus 5 in the hippocampal formation, regions around the third ventricle, caudate putamen and lateral habenular nucleus. Contrast, vimentin immunoreactivity consistently increased with progression of kindling in the cingulum and parietal cortex. These findings indicate dynamic changes in vimentin expression dependent on the kindling stage of seizure-prone state, and suggest that these changes play roles in formation of new circuits following kindling.