[Reactive microglial changes in rat neocortex and hippocampus after exposure to acute perinatal hypoxia].

The dynamics of reactive changes of a population density of microglial cells and the reversibility of their phenotypic forms were studied in the brain of neonatal rats at different time intervals after 1 hr-long exposure to acute normobaric hypoxia in the pressure chamber at the second postnatal day. Different areas of the neocortex (frontal, motor, somatosensory and visual) and of the hippocampus (CAI, CA3, CA4 and fascia dentata) were examined 1 hr, 3 hrs, 1 and 5 days after exposure to hypoxia. Microglial cells were demonstrated using an immunocytochemical staining with the monoclonal antibodies against Iba- 1 antigen. The results have shown that the reaction of microglia to acute hypoxia in both the neocortex and the hippocampus of the new-borns developed simultaneously and synchronously with the augmentation of cell death. The increase of a population density of amoeboid form of microglial cells in the brain areas studied was recorded already after 1 hour as a result of their migration from the subventricular region and the areas adjacent to large vessels from where they practically disappeared. The number of amoeboid microglial cells in this area has recovered rather quickly (in 3 hrs). The population densify of microglial cells, especially of amoeboid forms, sharply increased with the augmentation of cell death and remained unchanged for about 5 days.