軸索切断後の迷走神経核および舌下神経核の神経細胞とグリア細胞におけるp38 MAP kinaseの発現

Abstract

Mitogen－activated protein (MAP) kinase cascades are activated in response to various extracellular stimuli. p38 MAP kinase is one of the MAP kinase family and is activated in response to various extracellular stimuli such as proinflammatory cytokines and environmental stresses. To obtain information about the role of the p38 MAP kinase in the neurons and the glial cells after axotomy, we nvestigated changes of p38 MAP kinase expression in the dorsal motor nucleus(DMN) of the vagus nerve and the hypoglossal nucleus after axotomy in adult rats using in situ hybridization and immunohistochemical techniques. Expression of p38 MAP kinase mRNA was observed in the cytoplasms of the neurons in control rats, and showed no marked changes after axotomy. Three days after axotomy, however, expression of p38 MAP kinase mRNA was observed in the cytoplasms of perineuronal microglias in both nuclei. Immunohistochemical analysis revealed expression of p38 MAP kinase in the cytoplasms and nuclei of neurons in both nuclei in control rats. The stronger expression of activated p38 MAP kinase was observed in the DMN ofthe vagus nerve than in the hypoglossal nucleus. After axotomy，the expression of p38 MAP kinase, inactive and active, was reduced in the nuclei of neurons in both nuclei, while perineuronal microglias showed increased expression in their cytoplasms and nuclei. These findings indicate that the reduction of the expression of p38 MAP kinase, inactive and active, influences the transcription factors, and plays an important role in retrograde neuronal reactions. Moreover, the increased expression of p38 MAP kinase in the perineuronal microglias may be related to microglial cell reactions and retrograde neuronal reactions.