[The distribution of motoneuronotrophic factor 1 (MNTF1) and its receptor-like substance in the spinal cord and limb muscles of mice with motoneuron disease].

Using a monoclonal antibody for the motoneuronotrophic factor 1 (MNTF1) and its idiotypic antibody we have detected immunohistochemically the changes in the expression of the positive immunoreactivities for the MNTF1 and its receptor-like substance in the cervical and lumbar spinal cord regions as well as in the limb muscles of the wobbler mice, as the disease progressed from the first to the fourth stage. The results indicated that the positive immunoreactivities for the MNTF1 and its receptor-like substance were mainly located in the soma and neurites of the anterior born motoneurons at spinal layers VIII and IX and in the sarcoplasm of the skeletal muscles of the fore- and hind-limbs, and whereas their nuclei were immunoreactively negative. In the first stage (3 weeks) of the disease there were fewer in numbers of cells containing positive immunoreactivities (P < 0.01) and lesser in their relative amount of immunoreactivities per cell (P < 0.01) in the cervical and lumbar spinal cord as well as in the fore- and hind-limbs muscles of the wobbler mice as compared to those of the normal littermates. In the fourth stage (3 months) of the disease these differences between the wobbler mice and the normal littermates were even more distinct (P < 0.01 and P < 0.01). These results suggested that as syntheses of the skeletal muscle target cell-derived MNTF1 and its receptor-like substance were reduced to levels which were not enough to ensure the survival of motoneurons and consequently leading to muscular atrophy, as the motoneuron disease in wobbler mice deteriated.