Tissue nerve growth factor concentrations in neuromuscular diseases

In order to investigate the possible influences of pathological processes on muscle NGF levels in human subjects, we measured the NGF concentrations in muscle biopsies from 35 male and 16 female subjects (controls, n= 14; amyotrophic lateral sclerosis, n= 20; inflammatory myopathy, n= 6; muscular dystrophy, n= 11). The NGF concentration in each group was as follows: controls, 1.73 ± 0.3 pg/mg protein (mean ± S.E.M.); muscular dystrophies, 1.73 ± 0.48 pg/mg protein; inflammatory myopathies, 2.28 ± 1.45 pg/mg protein; amyotrophic lateral sclerosis, 4.15 ± 0.79 pg/mg protein. The tissue NGF concentrations were significantly (140%) higher in patients with ALS than in the control subjects (P < 0.05, Wilcoxon signed rank test). Age and gender had no influence on tissue NGF concentrations. We conclude that the NGF increases observed here in affected muscle in amyotrophic lateral sclerosis can best be explained in terms of rapidly progressing denervation processes.