Source Paper
Attenuation of age-related changes in mouse neuromuscular synapses by caloric restriction and exercise
Gregorio Valdez, Juan C. Tapia, Hyuno Kang, Gregory D. Clemenson, F. H. Gage et al.
Proceedings of the National Academy of Sciences • 2010
Caloric Restriction Intervention Study
Objective: To assess the effects of a lifelong calorie-restricted diet on age-related synaptic abnormalities, motor neuron loss, and muscle fiber turnover in 24-month-old mice, and to compare these effects with exercise intervention
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Protocol Steps
Establish caloric restriction intervention
Implement a lifelong calorie-restricted diet in mice from early age through 24 months
Note: This is a chronic intervention spanning the entire lifespan of the animals
View evidence from paper
“A life-long calorie-restricted diet significantly decreased the incidence of pre- and postsynaptic abnormalities in 24-mo-old mice”
Establish exercise intervention group
Provide wheel running exercise to 22-month-old mice
Note: Exercise intervention was applied later in life compared to caloric restriction which was lifelong
View evidence from paper
“One month of exercise (wheel running) in 22-mo-old mice also reduced age-related synaptic changes”
Assess neuromuscular junction structure
Examine skeletal neuromuscular junctions (NMJs) for age-related structural alterations including axonal swellings, sprouting, synaptic detachment, axonal withdrawal, and postsynaptic fragmentation
Note: Comparisons made between young adult, 18-month-old, and 24-month-old mice
View evidence from paper
“Comparison of NMJs in young adult and aged mice revealed a variety of age-related structural alterations, including axonal swellings, sprouting, synaptic detachment, partial or complete withdrawal of axons from some postsynaptic sites, and fragmentation of the postsynaptic specialization”
Quantify motor neuron loss
Count and assess motor neuron numbers to determine age-related motor neuron loss and effects of interventions
Note: Caloric restriction attenuated age-related loss of motor neurons; exercise had no effect on motor neuron number
View evidence from paper
“A life-long calorie-restricted diet significantly decreased the incidence of pre- and postsynaptic abnormalities in 24-mo-old mice and attenuated age-related loss of motor neurons”
Assess muscle fiber turnover
Evaluate muscle fiber turnover rates to determine age-related changes and intervention effects
Note: Caloric restriction attenuated age-related muscle fiber turnover; exercise had no effect on muscle fiber turnover
View evidence from paper
“A life-long calorie-restricted diet significantly decreased the incidence of pre- and postsynaptic abnormalities in 24-mo-old mice and attenuated age-related loss of motor neurons and turnover of muscle fibers”
Perform time-lapse in vivo imaging
Use time-lapse imaging to visualize and document synaptic alterations in living mice over time, particularly to assess whether exercise can reverse already-occurring synaptic changes
Note: This imaging revealed that exercise partially reversed synaptic alterations that had already occurred
View evidence from paper
“Time-lapse imaging in vivo revealed that exercise partially reversed synaptic alterations that had already occurred”