The fate of Nissl-stained dark neurons following traumatic brain injury in rats: difference between neocortex and hippocampus regarding survival rate
We studied the fate of Nissl-stained dark neurons (N-DNs) following traumatic brain injury (TBI). N-DNs were investigated in the cerebral neocortex and the hippocampus using a rat lateral fluid percussion injury model. Nissl stain, acid fuchsin stain and immunohistochemistry with phosphorylated extracellular signal-regulated protein kinase (pERK) antibody were used in order to assess posttraumatic neurons. In the neocortex, the number of dead neurons at 24 h postinjury was significantly less than that of the observed N-DNs in the earlier phase. Only a few N-DNs increased their pERK immunoreactivity. On the other hand, in the hippocampus the number of dead neurons was approximately the same number as that of the N-DNs, and most N-DNs showed an increased pERK immunoreactivity. These data suggest that not all N-DNs inevitably die especially in the neocortex after TBI. The fate of N-DNs is thus considered to differ depending on brain subfields.
KeywordsDark neuron Nissl stain Traumatic brain injury Extracellular signal-regulated protein kinase
We are grateful to A. Yano, N. Nomura and T. Suzuki for their valuable technical contributions to this work, and N. Tsuzuki, H. Katoh, S. Ishihara, T. Miyazawa and A. Onuki for helpful suggestions.
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