Am. Tata et al., CHOLINERGIC MARKERS ARE EXPRESSED IN DEVELOPING AND MATURE NEURONS OFCHICK DORSAL-ROOT GANGLIA, Journal of neuroscience research, 37(2), 1994, pp. 247-255
The presence of acetylcholinesterase has been reported in chick dorsal
root ganglia at early developmental stages although acetylcholine is
not known to play a role in these ganglia. Recently, we reported that
during development the level of acetylcholinesterase increases continu
ously and the enzyme becomes gradually expressed in all sensory neuron
s. These observations prompted the study of the developmental pattern
of expression of other cholinergic markers, such as choline acetyltran
sferase (ChAT) and the high affinity transport mechanism for choline.
ChAT activity is barely detectable at early developmental stages (E7)
and increases markedly thereafter, with an activity profile similar to
that described for acetylcholinesterase. A similar increase in enzyme
activity is also observed when ChAT is measured in dorsal root gangli
a explants and in dissociated cells in culture. The study of ChAT acti
vity in cultured cells shows an increase over a period of 3 days, thus
ruling out the hypothesis that motor fibers, still associated to the
ganglia, may represent a possible source of the enzyme. Immunostaining
of whole ganglia or cultured cells shows that ChAT immunoreactivity i
s not restricted to a specific neuronal subpopulation but appears as a
common marker of sensory neurons. High affinity choline uptake, block
ed by hemicholinium, is present in sensory neurons cultured from E7 do
rsal root ganglia. Observations on cultured neurons from later stages
(E18) indicate that choline transport is not a transient property of s
ensory neurons. These observations show a similar pattern of expressio
n of several cholinergic markers during development. Such a pattern is
maintained at significant levels also in mature ganglia. (C) 1994 Wil
ey-Liss, Inc.