Successful inhibition of excitotoxic neuronal damage and microglial activation after delayed application of interleukin-1 receptor antagonist (original) (raw)
2008, Journal of Neuroscience Research
Interleukin (IL)-1 is an important mediator of neuronal demise and glial activation after acute central nervous system lesions and is antagonized by IL-1 receptor antagonist (IL-1RA). Here we determined the time window in which IL-1RA elicits neuroprotective effects in rat organotypic hippocampal slice cultures (OHSC). OHSC were lesioned with N-methyl-D-aspartate (NMDA) and treated with IL-1RA (100 ng/ml) at different time points postinjury or were left untreated. Damaged neurons, microglial cells, and astrocytes were labelled with NeuN, propidium iodide, isolectin B 4 , or glial fibrillary acidic protein (GFAP), respectively, and were analyzed by confocal laser scanning microscopy. In lesioned OHSC, the most dramatic increase in microglial cell number occurred between 8 and 16 hr postinjury, and the maximal neuronal demise was found between 16 and 24 hr postinjury. The cellular source of IL-1b was investigated by immunohistochemistry, and IL-1b immunoreactivity was found in few microglial cells at 4 hr postinjury and in numerous microglial cells and astrocytes at 16 hr postinjury. In both glial populations, IL-1b immunoreactivity peaked at 24 hr postinjury. IL-1RA treatment potently suppressed neuronal damage by 55% when initiated within the first 16 hr postinjury (P < 0.05), and IL-1RA treatment initiated at 24 hr postinjury resulted in weaker but still significant neuroprotection. IL-1RA treatment also reduced the number of microglial cells significantly when initiated within 36 hr postinjury (P < 0.05). In conclusion, IL-1RA exhibits significant neuroprotective effects in this in vitro model of excitotoxic injury even after delayed application. V
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