In fact, rAAV-derived GDNF was substantially expressed and distributed in a large number of myofibers, mainly in the vicinity of the sarcolemma after intramuscular infection of the rAVV-GDNF gene and predominantly concentrated at the sites of neuromuscular junctions [36], suggesting retrograde axonal transport of GDNF from muscle to motoneurons. This evidence concerns the gene GDNF and infection.