Journal of Neuroscience, Vol 10, 3992-4005, Copyright © 1990 by Society for Neuroscience
Cell interactions regulate dendritic morphology and responses to neurotransmitters in embryonic chick sympathetic preganglionic neurons in vitro
B Clendening and RI Hume
Department of Biology, University of Michigan, Ann Arbor 48109.
The influence of non-neuronal cells and interneurons on the morphological
development of chick sympathetic preganglionic neurons (SPNs) and on the
responsiveness of these neurons to the neurotransmitters GABA, glycine, and
glutamate was studied. SPNs were retrogradely labeled with the fluorescent
dyes dil and diO, then separated from spinal-cord non-neuronal cells and
interneurons by fluorescence-activated cell sorting. SPNs were grown in
culture, either alone or in coculture with non-neuronal cells alone, with
interneurons alone, or with both of these cell types (control cultures).
The responsiveness of SPNs to neurotransmitters was assessed by whole-cell
recording, while cell morphology was assessed after intracellular staining
with 6-carboxyfluorescein. Cell size and morphology were affected by
non-neuronal cells. In the absence of non-neuronal cells, SPNs had smaller
cell bodies and fewer major processes, whether or not interneurons were
present. In contrast, responses to the 3 neurotransmitters were affected by
both non-neuronal cells and interneurons, but in ways that differed
slightly for each transmitter. In the absence of both non-neuronal cells
and interneurons, responses to all 3 transmitters were much smaller than in
control cultures, with responses to glutamate most profoundly affected. The
addition of either non-neuronal cells or interneurons slightly increased
the amplitude of SPN responses to glutamate, but the level of
responsiveness with either cell type alone was much lower than for SPNs
grown in the presence of both cell types. The addition of interneurons also
slightly increased the responsiveness of SPNs to GABA, but non-neuronal
cells alone had no significant effect on the responses of SPNs to GABA.
Finally, the glycine responsiveness of SPNs was raised to control levels
when either non-neuronal cells or interneurons were added. These
experiments demonstrate that, though interneurons can have a significant
inductive effect on the responses of SPNs to neurotransmitters, not all of
the changes in neurotransmitter responsiveness can be related to the
formation of functional synapses.