GDNF and amyotrophic lateral sclerosis: In this sense, recent contributions suggest that MN loss in ALS occurs in a dying back pattern starting from skeletal muscle and NMJ abnormalities and progressing to the neuronal cell body [23, 30, 65, 81]; and skeletal muscle-derived [27, 52, 82] but not motoneuron-derived GDNF expanded the lifespan of SOD1G93A mice [31, 83].