Removal of GABA within adult modulatory systems alters electrical coupling and allows expression of an embryonic-like network

E. Ducret, Y. Le Feuvre, P. Meyrand, V. S. Fenelon
Journal of Neuroscience. 2007-04-04; 27(14): 3626-3638
DOI: 10.1523/JNEUROSCI.4406-06.2007

PubMed
Read on PubMed



Ducret E(1), Le Feuvre Y, Meyrand P, Fénelon VS.

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.

The maturation and operation of neural networks are known to depend on modulatory
neurons. However, whether similar mechanisms may control both adult and
developmental plasticity remains poorly investigated. To examine this issue, we
have used the lobster stomatogastric nervous system (STNS) to investigate the
ontogeny and role of GABAergic modulatory neurons projecting to small pattern
generating networks. Using immunocytochemistry, we found that modulatory input
neurons to the stomatogastric ganglion (STG) express GABA only after
metamorphosis, a time that coincides with the developmental switch from a single
to multiple pattern generating networks within the STNS. We demonstrate that
blocking GABA synthesis with 3-mercapto-propionic acid within the adult
modulatory neurons results in the reconfiguration of the distinct STG networks
into a single network that generates a unified embryonic-like motor pattern.
Using dye-coupling experiments, we also found that gap-junctional coupling is
greater in embryos and GABA-deprived adults exhibiting the unified motor pattern
compared with control adults. Furthermore, GABA was found to diminish directly
the extent and strength of electrical coupling within adult STG networks.
Together, these observations suggest the acquisition of a GABAergic phenotype by
modulatory neurons after metamorphosis may induce the reconfiguration of the
single embryonic network into multiple adult networks by directly decreasing
electrical coupling. The findings also suggest that adult neural networks retain
the ability to express typical embryonic characteristics, indicating that network
ontogeny can be reversed and that changes in electrical coupling during
development may allow the segregation of multiple distinct functional networks
from a single large embryonic network.

 

Know more about