Bone morphogenetic protein-6 is expressed early by activated astrocytes in lesions of rat traumatic brain injury.

We have analyzed early expression of bone morphogenetic protein-6 in rat brains subjected to traumatic brain injury. Bone morphogenetic protein-6 was expressed in neurons of the hippocampus and cortex in normal adult rat brains. A pronounced expression of bone morphogenetic protein-6 in astroglia located to the lesion became obvious 48 h postinjury. Bone morphogenetic protein-6(+) glia were distributed around the lesion, thus demarcating the injured tissue from normal brain. Double labeling by immunohistochemistry revealed that the major glial sources for bone morphogenetic protein-6 were reactive astrocytes and few ED1(+) or W3/13(+) cells co-expressed bone morphogenetic protein-6. Furthermore, bone morphogenetic protein-6 expression in neurons located to hippocampus and cortex of the lesioned hemisphere was up-regulated 3 days postinjury. In conclusion, this is the first description of bone morphogenetic protein-6 expression in traumatic brains. Our data suggest that bone morphogenetic protein-6 might be involved in astrogliosis and neuron protection following traumatic brain injury.