N. Chauvet et al., IMMUNOCYTOCHEMICAL STUDY OF PHENOTYPIC PLASTICITY OF CULTURED DORSAL-ROOT GANGLION NEURONS DURING DEVELOPMENT, International journal of developmental neuroscience, 13(7), 1995, pp. 673-683
Rat dorsal root ganglia (DRG) were cultured from different stages of d
evelopment ranging from embryonic day-14 to adult. The expression of e
ight neurotransmitter phenotypes was examined with immunocytochemical
detection and the percentages of each phenotype were calculated with r
eference to the whole neuronal population defined by the expression of
neuron specific enolase (NSE). The expression of peptides, calcitonin
gene-related peptide (CGRP), substance P (SP), cholecystokinin (CCK)
and neuropeptide Y (NPY) was always present whatever the age at onset
of the cultures. Although the percentage of CGRP remained stable, that
of the other peptides declined progressively. Their in-vitro expressi
on did not differ markedly from that found in vivo. Another group of n
eurotransmitters, including 5-hydroxytryptamine (5-HT), thyrotropin-re
leasing hormone (TRH) and gamma-aminobutyric acid (GABA) was never exp
ressed in situ in DRG neurons. In culture, they were expressed in a hi
gh percentage of neurons, especially for 5-HT and TRH, and they showed
a similar evolution, with a decrease at early postnatal ages followed
by a further increase. This profile suggests that the expression of t
hese transmitters is strongly environment-dependent and may be repress
ed in situ. Finally, somatostatin (SOM) was found only in cultures pre
pared from adult tissues, whereas it was present in situ from the embr
yo onwards. The expression of this peptide would thus require a stabil
ization by a long exposure to environmental factors. We can conclude t
hat the great diversity of phenotypic expression found in DRG neurons
in situ is the result of a wide variety of influences occurring at dif
ferent stages of development in a large potential repertory present in
these neurons.