FKBP12 immunoreactivity in the human spinal cord of motor neuron disease patients

We investigated the FKBP12 immunoreactivity in the spinal cord of neurological controls and motor neuron disease (MND) patients. In the neurological controls, the spinal neurons were markedly stained with antihuman FKBP12 (N-19 and C-19) antibodies. FKBP12 immunoreactivity was associated with lipofuscin in formalin-fixed paraffin-embedded samples. In an electron microscopic view, the 10-nm colloidal gold particles labeled by the anti-FKBP12 (N-19) antibody were present on the lipofuscin of the spinal anterior horn neurons. In the MND cases, atrophic neurons with an abundance of lipofuscin granules in the anterior horns of the spinal cord were mildly stained with the anti-FKBP12 (N-19 and C-19) antibodies. Normal-appearing neurons, inclusion-laden neurons and chromatolytic neurons of MND cases were weak or negatively stained with anti-FKBP12 (N-19) antibodies. These findings suggest that FKBP12 (N-19) may decrease in the early stages of degeneration in MND. Complexes of FKBP12 and ligands were reported to have neuroprotective and/or neuroregenerative properties. It is speculated that the decrease in FKBP12 (N-19) plays some causative role in the development of neurodegeneration in MND. Further investigation of FKBP12 and ligands may help elucidate the pathogenesis of MND.