Abstract

The long-term goal of this study is to understand the mechanism of motor neuron diseases.
The specific aims of this proposal are to test whether or not survival of motor neurons is controlled by the peripheral target of innervation or by the afferent input to the motor neuron. The role of the target in the control of survivors will be determined by reducing the size of the target for the trochlear motor neurons. For this, the superior oblique muscle of quail embryos will be grafted in the place of that of duck embryos. The development of the target, motor neurons and neuromuscular connections will be examined morphologically and physiologically. The number of trochlear motor neurons surviving by virtue of innervating the smaller target will be counted. The role of afferent input in the control of neuron numbers will be determined by monitoring neuron survival in the absence of afferent input and also following increased afferents. The troclear motor neurons will be deprived of their afferent input by removal of the hindbrain. The amount of afferent projection will be increased by substituting the hindbrain of quail embryos with the same neural tissue from duck embryos. Results of the proposed study should indicate whether the mechanism for the control of motor neuron numbers resides in the target muscle or in the CNS.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD017800-07
Application #
3314825
Study Section
Human Embryology and Development Subcommittee 2 (HED)
Project Start
1986-07-01
Project End
1991-06-30
Budget Start
1989-07-01
Budget End
1990-06-30
Support Year
7
Fiscal Year
1989
Total Cost
Indirect Cost

  Institution

Name
Medical College of Georgia (MCG)
Department
Type
Schools of Medicine
DUNS #
City
Augusta
State
GA
Country
United States
Zip Code
30912

  Publications

Sohal, G S (1995) Sixth Annual Stuart Reiner Memorial Lecture: embryonic development of nerve and muscle. Muscle Nerve 18:2-14
Sohal, G S (1992) The role of target size in neuronal survival. J Neurobiol 23:1124-30
Sohal, G S; Hirano, S; Kumaresan, K et al. (1992) Influence of altered afferent input on the number of trochlear motor neurons during development. J Neurobiol 23:10-6
Hirano, S; Kumaresan, K; Ali, M M et al. (1991) Synapse formation on trochlear motor neurons in relation to naturally occurring cell death during development. Int J Dev Neurosci 9:371-9
Sohal, G S; Kumaresan, K; Hirano, S et al. (1991) Synapse formation on trochlear motor neurons under conditions of increased and decreased cell death during development. Int J Dev Neurosci 9:563-70
Hirano, S; Fuse, S; Sohal, G S (1991) The effect of the floor plate on pattern and polarity in the developing central nervous system. Science 251:310-3
Sohal, G S; Stoney, S D; Campbell, L R et al. (1991) Influence of grafting a smaller target muscle on the magnitude of naturally occurring trochlear motor neuron death during development. J Comp Neurol 304:187-97
Sohal, G S; Bal, H S; Campbell, L R et al. (1990) Synapse formation on quail trochlear neurons transplanted in duck embryos before naturally occurring motor neuron death. Int J Dev Neurosci 8:9-16
Yamashita, T; Sohal, G S (1987) Embryonic origin of skeletal muscle cells in the iris of the duck and quail. Cell Tissue Res 249:31-7
Sohal, G S; Sickles, D W (1986) Embryonic differentiation of fibre types in normal, paralysed and aneural avian superior oblique muscle. J Embryol Exp Morphol 96:79-97

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