Up-regulation of glial cell line-derived neurotrophic factor (GDNF) expression in regenerating muscle fibers in neuromuscular diseases.

Glial cell line-derived neurotrophic factor (GDNF) has been shown to exert a target-derived trophic factor for motor neurons. Immunohistochemical analyses revealed that expression of GDNF in regeneration muscle fibers was up-regulated in polymyositis (PM) and Duchenne type muscular dystrophy (DMD). Reverse transcriptase polymerase chain reaction (RT-PCR) analyses showed that the full length GDNF was up-regulated in PM and DMD muscle; normal muscle exhibited mostly truncated GDNF. The results indicate that the GDNF expression is regulated in regeneration of human skeletal muscle.