Journal of Neuroscience, Vol 6, 439-447, Copyright © 1986 by Society for Neuroscience
Selective effects of skeletal muscle extract fractions on motoneuron development in vitro
RG Smith, K Vaca, J McManaman and SH Appel
In vivo labeling of motoneurons with retrogradely transported wheat germ
agglutinin, and in situ staining of cholinergic neurons with a monoclonal
antibody against CAT, have been used as methods to identify motoneurons in
cultures of dissociated 14 d embryonic rat ventral spinal cord. With these
two different labeling techniques, we demonstrate that skeletal muscle
extracts maintain motoneuron survival, and induce motoneuron morphologic
and cholinergic differentiation in vitro. Further, we show that several
partially purified muscle extract- derived proteins separately augment each
of these specific parameters of motoneuron development. A 55,000 Da neutral
glycoprotein specifically induces both ACh synthesis and
motoneuron-selective process outgrowth and elongation, while a 1200-1500 Da
peptide selectively augments both apparent motoneuron survival and ACh
synthesis. A third trophic agent, a 33,000-35,000 Da acidic glycoprotein,
induces process outgrowth in both motoneurons and nonmotoneurons of the
ventral spinal cord, but has no effect on ACh synthesis.