Transition to Endogenous Bursting After Long-Term Decentralization Requires De Novo Transcription in a Critical Time Window
Journal of Neurophysiology. 2000-07-01; 84(1): 596-599
DOI: 10.1152/jn.2000.84.1.596
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Thoby-Brisson M(1), Simmers J.
Author information:
(1)Laboratoire de Neurobiologie des Réseaux, Université Bordeaux I and Centre
National de la Recherche Scientifique- Unité Mixte de Recherche 5816, 33405
Talence, France.
Rhythmic motor pattern generation by the pyloric network in the lobster
stomatogastric ganglion (STG) requires neuromodulatory inputs from adjacent
ganglia. However, although suppression of these inputs by cutting the
stomatogastric nerve (stn) causes the pyloric network to fall silent, network
output similar to that expressed when the stn is intact returns after 3-4 days in
organ culture. Intracellular recordings from identified pyloric dilator (PD)
neurons indicate that the fundamental change underlying rhythm recovery resides
with the intrinsic excitability of pyloric neurons themselves, since the
prolonged absence of extrinsic modulatory inputs allows the expression of an
endogenous oscillatory capability that is maintained in a strictly conditional
state when these inputs are present. To examine whether gene transcription was
involved in this change in neuronal behavior, we performed in vitro experiments
in which the STG was exposed to the RNA-synthesis inhibitor actinomycin D (ACD).
ACD (50 microM) incubation at the time of decentralization prevented subsequent
reacquisition of PD neuron bursting, but the inhibitor was much less effective
when applied at later postdecentralization times, suggesting that the recovery
process arises from new protein synthesis triggered when modulatory inputs are
first removed. Moreover, in the nondecentralized STG, trans-synaptic modulatory
instruction may sustain the conditional pyloric network phenotype by continuously
regulating expression of genes responsible for intrinsic neuronal rhythmogenesis.