Reply to ‘Mitochondrial changes in skeletal muscle in amyotrophic lateral sclerosis and other neurogenic atrophies—a comment’

Abstract

Based on new biochemical data, Vielhaber et al . (2005) made some comments on our recent findings on mitochondrial changes in skeletal muscle of patients with sporadic amyotrophic lateral sclerosis (ALS) (Krasnianski et al ., 2005). However, the interpretation of the new data by Vielhaber et al . needs some critical discussion. There are three separate issues that have clearly to be differentiated: (i) mitochondrial dysfunction in the CNS in ALS, (ii) mitochondrial dysfunction in skeletal muscle in ALS and (iii) mitochondrial dysfunction in atrophic skeletal muscle due to other neurogenic diseases. There is accumulating evidence for mitochondrial dysfunction in the CNS in ALS (Bowling et al ., 1993; Fujita et al ., 1996; Borthwick et al ., 1999; Wiedemann et al ., 2002). This issue, however, was neither the objective of our study nor of the studies by Vielhaber et al . (2000, 2003, 2005). In contrast to mitochondrial involvement in the CNS, the data on dysfunction of skeletal muscle mitochondria in ALS are controversial. For a long time it has been clearly established that chronic denervation can be associated with histological abnormalities such as core and target formations suggesting non-specific mitochondrial changes in denervated muscle (Dubowitz and Brooke, 1973). This implies that any investigation of mitochondrial …