The project uses a thin snake muscle to study the determinants of synaptic strength, or efficacy, at the neuromuscular junction. The project's focus is to examine the structure and function of synapses within individual motor units which have been identified in a living preparation. The first goal is to determine the quantal release parameters of individual boutons which comprise nerve terminals in snake muscles. Quantal content will be compared to bouton size and ultrastructure to determine if the terminal bouton serves an an anatomical correlate of synaptic strength. Second, synaptic strength will be compared to indicators of target cell requirements, such as input resistance, at all synapses supplied by one motor axon. This will permit the influence of target cell properties on synaptic strength to be independently assessed. Finally, synaptic strength will be systematically compared among all motor units within the muscle. This will permit the influence of motor neuron size and type to be independently determined for synapses whose target-related properties are precisely known. These measurements will determine the extent to which synaptic efficacy is an intrinsic motor neuron property, and how efficacy relates to other neuron properties. Knowledge of these relationships is essential in understanding how the size and strength of synapses are regulated, and why such regulation fails in diseases which attack pre- or postsynaptic cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29NS024752-04
Application #
3476838
Study Section
Neurology B Subcommittee 2 (NEUB)
Project Start
1987-04-01
Project End
1992-03-31
Budget Start
1990-04-01
Budget End
1991-03-31
Support Year
4
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Washington University
Department
Type
Schools of Medicine
DUNS #
062761671
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
Stewart, Richard S; Teng, Haibing; Wilkinson, Robert S (2012) ""Late"" macroendosomes and acidic endosomes in vertebrate motor nerve terminals. J Comp Neurol 520:4275-93