The Journal of Neuroscience, September 1, 1998, 18(17):6905-6913
Peripheral and Central Target Requirements for Survival of
Embryonic Rat Dorsal Root Ganglion Neurons in Slice Cultures
Richard
Wetts and
James E.
Vaughn
Division of Neurosciences, Beckman Research Institute of the City
of Hope, Duarte, California 91010
Developmental cell death in the nervous system usually is
controlled by the availability of target-derived trophic factors. It is
well established that dorsal root ganglia (DRG) neurons require the
presence of their peripheral target for survival, but because of their
central projections, it is possible that the spinal cord also may be
required. Before examining this possibility in rat embryos, we first
used terminal deoxynucleotidyl transferase-mediated biotinylated UTP
nick end labeling (TUNEL) to determine that thoracic DRG cell death
occurred from embryonic day 15 (E15) to E18. To determine the target
requirements of DRG neurons, we used organotypic slice cultures of E15
thoracic trunk segments. After peripheral target removal, essentially
all DRG neurons disappeared within 5 d. In contrast, after removal
of the spinal cord, approximately half of the DRG neurons survived for
at least 8 d. Hence, some E15 DRG neurons could survive without
the spinal cord. However, those DRG neurons that died after spinal cord
ablation apparently required trophic factors from both central and
peripheral targets, because the presence of only one of these tissues
was not adequate by itself to support this cell group. Addition of
neurotrophin-3 (NT-3) to the culture medium rescued some DRG neurons
after CNS removal, suggesting a possible role for NT-3 in
vivo. In other experiments, cultures were established from
older (E16) embryos, and essentially all neurons survived after spinal
cord ablation, even without added factors. These and other experiments
indicated that ~65% of DRG neurons are transiently dependent on the
CNS early in development.
Key words:
apoptosis; NADPH-diaphorase histochemistry; nerve growth
factor; neurotrophin-3; organotypic slice culture; sensory neurons; TUNEL histochemistry
Copyright © 1998 Society for Neuroscience 0270-6474/98/18176905-09$05.00/0