olgchechneva.pdf [1.17 mb] |Neurodegeneration and neurogenesis in organotypic hippocampal slice cultures after oxygen and glucose deprivation|
|Organotypic hippocampal slice cultures neurogenesis posterior periventricle oxygen-glucose deprivation microglia inflammation|
Adult neurogenesis plays a role in many physiological (memory formation) and pathological (stroke, depression) processes. In the present study early neurogenesis in vitro in rat organotypic hippocampal slice cultures (OHC) was characterized and the complex interplay between neuronal damage, microglia activation, cell proliferation, neurogenesis and the role of inflammation after oxygen-glucose deprivation (OGD) was investigated. Glial envelope, covering the slice was formed by GFAP or GFAP/Nestin positive astrocytes and activated microglia during slice cultivation. In addition to the dentate gyrus (DG) OHC included a second neurogenic zone: the posterior periventricle (pPV), which is a part of the lateral ventricle wall. Nestin+ cells with stellar morphology were found in the DG, while elongated Nestin+ cells were present in the pPV. bFGF treatment induced a fast but short-lasting neurogenic response in the DG while the pPV showed a more pronounced and long lasting neurogenic effect of bFGF. After exposure of OHC to 40 min OGD microglia activation and upregulation of IL-1beta, TNF-alpha and IL-6 mRNA (2h after OGD) preceded the development of neuronal damage (6h after OGD) that was followed by an increase in cell proliferation (16h after OGD). Neurogenesis was inhibited at 3d after OGD in both neurogenic zones, however the restoration of neurogenesis was already observed at 6d. At this time point a significant increase of newly generated neurons was found in the pPV compared to control. Number of BrdU/ß-III Tubulin+ neurons was significantly increased in the pPV of OGD-exposed OHC by bFGF application. MK-801, indomethacin or minocycline prevented the OGD-induced neuronal damage, cell proliferation and caused a decrease of OX-42+ microglia in the damaged area. However indomethacin or minocycline did not affect OGD-induced neurogenesis in the pPV. This study is the first to show that i) two neurogenic zones, the DG and the pPV, are present in interface OHC; ii) the DG and pPV contain neural precursors with different neurogenic properties. High neurogenesis occur in the pPV while low neurogenesis is present in the DG of OHC; iii) inflammation is mounted in OHC at early time point after OGD. It is associated with activation, migration and proliferation of microglia; iv) due to microenvironmental changes neurogenesis in both neurogenic zones is inhibited early after OGD (3d) and restored later on (6d). OGD stimulates neurogenesis in the pPV; v) neuroprotection against OGD-induced damage in OHC by anti-inflammatory treatment is associated with intact neurogenesis. Taking together, these in vitro data represent the evidences of injury-regulated neurogenesis in relation with inflammation in OHC that could be useful for further understanding of mechanisms of neurogenesis and anti-inflammatory treatment strategies after cerebral ischemia.