Some evidence for concurrent involvement of the fore- and hindleg muscles in murine muscular dystrophy.

Endurance of the forelegs of the dystrophic mouse was found to be significantly less than that of the normal mouse as early as at 3 weeks of age. It decreased progressively with age although the forelegs seemed to function almost normally even after 2 months of age by which time the hindlegs became almost immobile. Thus, histological and biochemical studies to compare the fore- and hindleg muscles of the dystrophic mice were conducted. Morphological abnormalities similar to those observed in the hindleg muscle were also found in foreleg muscles of the young dystrophic mice. Their foreleg and hindleg muscles showed significantly higher hydroxyproline contents than those of the normal mice even at 2 weeks of age when clinical signs of the disease first became manifest in their hindlegs. The present findings appear to be the first evidence for concurrent involvement of the fore- and hindleg muscles in murine muscular dystrophy. This would raise an issue as to why forelegs with abnormal muscles can subserve somewhat normal function, whereas hindlegs with abnormal muscles can subserve somewhat function, whereas hindlegs in these adult dystrophic mice are immobile. This might yield clues to clarify the mechanism underlying the aggravation of the disease.