Mp. Primi et Pgh. Clarke, EARLY RETROGRADE EFFECTS OF BLOCKING AXOPLASMIC-TRANSPORT IN THE AXONS OF DEVELOPING NEURONS, Developmental brain research, 99(2), 1997, pp. 259-262
Depriving developing neurons of retrograde trophic support may disrupt
their development and often causes them to die. We here report the ef
fects, in chick embryos, of eliminating retrograde support in the isth
mo-optic projection by blocking axoplasmic transport in the terminal p
arts of the axons, which is known ultimately to kill the isthmo-optic
neurons. Within only 9 h, this had perturbed the process of cellular r
eorganisation that eventually leads to the laminated appearance of the
mature isthmo-optic nucleus. Neuron survival in the isthmo-optic nucl
eus was affected even more quickly, but the earliest change, occurring
in as little as 3 h, was not an increase in the number of dying neuro
ns, but a decrease below control values. This novel effect was still p
resent at 6 and 9 h after the injection, but at longer survival times
the number of dying neurons increased well above control values as exp
ected. Our interpretation of the transient decrease in neuronal death
is that retrograde trophic signals include both death-promoting and li
fe-promoting components, and that the former act faster in this system
. (C) 1997 Elsevier Science B.V.