A penetrating brain injury produces a glial scar formed by astrocytes, oligodendrocytes, microglia and NG2 cells. Glial scar is a barrier preventing the extent of damage but it has deleterious effects in the regeneration of the axons. Estradiol and tamoxifen reduce gliosis and have neuroprotective effects in the hippocampus and the spinal cord. We evaluated the proliferation of glia and the electrocorticogram in the sensorial cortex in a brain injury model. At seven days post-injury, estradiol, tamoxifen and estradiol plus tamoxifen reduced the number of resident and proliferative NG2 and reactive astrocyte vimentin+ cells. Estradiol and tamoxifen effects on NG2 cells could be produced by the classical oestrogen receptors found in these cells. The glial scar was also reduced by tamoxifen. At thirty days post-injury, the amount of resident and proliferative astrocytes increased significantly, except in the estradiol plus tamoxifen group, whilst the oligodendrocytes proliferation in the glial scar was reduced in treated animals. Tamoxifen promotes the survival of FOX-3+ neurons in the injured area and a recovery in the amplitude of electrocorticogram waves. At thirty days, estradiol did not favour the suvival of neurons but produced a greater number of reactive astrocytes. In contrast, the number of oligodendrocytes was reduced. Tamoxifen could favour brain repair promoting neuron survival and adjusting glial cell number. It seems to recover adequate neural communication. � 2013 Elsevier Inc.
