Ontogenic changes of the spinal GABAergic cell population are controlled by the serotonin (5-HT) system: Implication of 5-HT1 receptor family

1. J Neurosci. 2005 Sep 21;25(38):8714-24.

Ontogenic changes of the spinal GABAergic cell population are controlled by the
serotonin (5-HT) system: implication of 5-HT1 receptor family.

Allain AE(1), Meyrand P, Branchereau P.

Author information:
(1)Laboratoire de Neurobiologie des Réseaux, Université Bordeaux 1, Centre
National de la Recherche Scientifique, Unité Mixte de Recherche 5816, 33405
Talence cedex, France.

During the development of the nervous system, the acquisition of the GABA
neurotransmitter phenotype is crucial for neural networks operation. Although
both intrinsic and extrinsic signals such as transcription factors and growth
factors have been demonstrated to govern the acquisition of GABA, few data are
available concerning the effects of modulatory transmitters expressed by axons
that progressively invade emerging neuronal networks. Among such transmitters,
serotonin (5-HT) is a good candidate because serotonergic axons innervate the
entire CNS at very early stages of development. We have shown previously that
descending 5-HT slows the maturation of inhibitory synaptic transmission in the
embryonic mouse spinal cord. We now report that 5-HT also regulates the
spatiotemporal changes of the GABAergic neuronal population in the mouse spinal
cord. Using a quantitative confocal study performed on acute and cultured spinal
cords, we find that the GABAergic population matures according to a similar
rostrocaudal temporal gradient both in utero and in organotypic culture.
Moreover, we show that 5-HT delays the appearance of the spinal GABAergic system.
Indeed, in the absence of 5-HT descending inputs or exogenous 5-HT, the GABAergic
population matures earlier. In the presence of exogenous 5-HT, the GABA
population matures later. Finally, using a pharmacological approach, we show that
5-HT exerts its action via the 5-HT1 receptor family. Together, our data suggest
that, during the course of the embryonic development, 5-HT descending inputs
delay the maturation of lumbar spinal motor networks relative to brachial
networks.

DOI: 10.1523/JNEUROSCI.2398-05.2005
PMID: 16177041 [Indexed for MEDLINE]

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