The inhibitor of DNA binding 2 is mainly expressed in oligodendrocyte lineage cells in adult rat brain

The inhibitor of DNA binding 2 (Id2) plays an important role in the brain both during embryogenesis and adulthood. But in adult rat brain, it is still unknown whether Id2 immunoreactivity mainly exhibits in neuronal, astrocytic and/or oligodendrocyte lineage cells. It is also unclear where and when Id2 immunoreactivity mainly exhibits in oligodendrocyte lineage cells. The present study showed 90% of Id2-immunoreactivity in oligdendrocyte lineage cells in such brain regions as the corpus callosum, optic chiasm, the longitudinal fasciculus of pons, the medial septal nucleus, the fimbria of hippocampus, the anterior commissure, and the pyramidal tract. Five percent of Id2-immunoreactivity was found in astrocytes. Id2 immunoreactivity was localized in neurons of only a few brain regions. Seventy percent of Id2 immunoreactivity was found in CC-1-positive mature oligodendrocytes. These observations suggest that Id2 may be mainly involved in terminal maturation of oligodendrocytes and myelination.