[Neonatal hypoxic/ischemic encephalopathy: neuropathology and plasticity].

To obtain some clues for early management after neonatal hypoxic/ischemic brain injury, the cascade of cellular responses to the lesions was examined. Microglia is one of the principal glial element that responds to ischemic lesions. Microglia and astroglia may play important roles in neuronal degeneration and regeneration through secretion of some substances, such as neurotrophic factors which have been known to protect and/or rescue injured neurons. Platelet-derived growth factor B chain PDGF-B chain) is one of the neurotrophic factors, and an immediate enhancement of the expression of PDGF-B chain mRNA, protein and its receptor was observed in the injured brain. This enhancement persisted longer only in the neurons in the peri-infarct. Our findings suggested the crucial role of PDGF-B chain in the impending brain injury, as a neuroprotecting factor. Clinical application of neurotrophic factors is not anecdotal.