Oxidation state of tissue thiol groups and content of protein carbonyl groups in chickens with inherited muscular dystrophy.

Indirect evidence suggests that oxidative stress may play a role in the pathogenesis of inherited muscular dystrophy, but the significance and precise extent of this contribution is poorly understood. Compared with normal muscle, significantly higher contents of glutathione, glutathione disulphide, protein-glutathione mixed disulphides and protein carbonyl groups, and significantly lower contents of free protein thiol groups, were found in pectoralis major muscle of genetically dystrophic chickens (the muscle affected by this disease) at 4 weeks of age. Other tissues did not show such marked disease-related differences. Interestingly, the protein pool in normal, but not dystrophic, pectoralis major muscle was relatively less oxidized in relation to the glutathione pool as compared with other tissues studied. The mechanisms by which this unique relationship between the thiol pools is maintained remain unknown. Although the physiological consequences of the increased content of protein carbonyl groups and the altered thiol pools in dystrophic muscle are not clear, the changes evident at such a young age are consistent with the occurrence of oxidative stress and may reflect significant damage to cellular proteins in this disease.