Article

Age-associated skeletal muscle weakness is a major contributing factor
to an increased late life mortality and morbidity, but its neurobiology is poorly
understood. Previously, we provided histological evidence of dying-back axonal
degeneration of motor neurons and denervation of neuromuscular junctions in
age-associated muscle weakness. Given this, we aimed to evaluate the relation
between impaired neuromuscular transmission and various aspects of age-associated
muscle weakness.
DESIGN: We compared two electrophysiological measures,
single-fiber jitter and compound motor action potential in mice of different age
groups, and correlated them with various physical performance measures, such as
grip strength, standing and walking time, and treadmill performance. RESULTS:
Consistent with our previous histological data, single-fiber jitter, a measure of
neuromuscular junction transmission, was significantly increased in older
animals, whereas compound motor action potential shows no difference between
young and old age groups. Neither jitter nor compound motor action potential
correlated with any of physical performance measures, except for jitter and
standing activity. CONCLUSIONS: Impaired neuromuscular transmission-represented
as increase in single-fiber electromyography jitter level-reflects decline in
motor function with aging.

Langue : ANGLAIS