The reciprocal change of neurotrophin-4 and glial cell line-derived neurotrophic factor protein in the muscles, spinal cord and cerebellum of the dy mouse.

Laminin alpha2 (merosin)-deficient congenital muscular dystrophy (CMD) patients show progressive muscle fiber necrosis and ineffective muscle regeneration, probably due to a lower formation of multinucleated myotubes due to an adhesion defect of myoblasts to each other. Some recent studies found that CMD patients have a white matter disorder and cerebellum atrophy. In the spinal cord of dy mice, a model of CMD, inducible nitric oxide synthase (iNOS) was markedly expressed. Using Western blotting and immunohistochemical analyses, we investigated the levels of neurotrophin-4 (NT-4), brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor (GDNF) and ciliary neurotrophic factor (CNTF) in the central nervous system and skeletal muscles of dy mice. In the dy mice, the microtubule-associated protein-2 (MAP-2) protein level was markedly decreased in the Purkinje and granule cells of the cerebellum, and in lumbar motoneurons of the spinal cord. The motoneurons and axons of dy mice possessed lower expressions of phosphorylated tau. The amount of NT-4 was markedly lower in the cerebellum, spinal cord and hindlimb muscles of dy mice. In dy mice, GDNF was markedly enhanced in the Purkinje and granule cells of the cerebellum, in many lumbar motoneurons, and in the regenerating atrophied fibers. The CNTF protein level did not differ in the hindlimb muscles between the normal and dy mice. Therefore, GDNF could act to inhibit the death of Purkinje and granular neurons, and motoneurons, and to promote the remodeling of the neuromuscular junction of atrophied muscle fibers of dy mice. Furthermore, dy mice include neurogenic abnormalities in the cerebellum and spinal cord along with myogenic disorder of muscle fibers.