Journal of Neuroscience, Vol 5, 3145-3153, Copyright © 1985 by Society for Neuroscience
Formation of electrical synapses between isolated, cultured Helisoma neurons requires mutual neurite elongation
RD Hadley, DA Bodnar and SB Kater
Our previous experiments have suggested the hypothesis that conjoint active
neuronal outgrowth may be necessary for formation of new electrical
synapses between identified neurons of adult Helisoma buccal ganglia. This
growth dependence hypothesis now has been tested by examining the responses
of individual pairs of neurons in isolation from the influences of the
ganglionic environment. Isolated cell culture of identified neurons (neuron
5) showed that: (i) neurons growing in cell culture undergo a predictable
sequence of morphological changes culminating in a stable morphological
state (i.e., growth stops); (ii) contact between actively growing neurons
in cell culture results in the formation of electrical connections, just as
in ganglia; and (iii) when an actively growing neuron encounters a neuron
that is morphologically stable, electrical connections do not form or are
very weak, even though strong connections are made between pairs of
actively growing neurons in the same culture. These results establish that
processes closely associated with growth are required for formation of
electrical synapses between these neurons.
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