Transplantation of embryonic Raphe cells regulates the modifications of the gabaergic phenotype occurring in the injured spinal cord.
Transection of the spinal cord yields a permanent deficit due to the interruption of descending and ascending tracts which subserve the supraspinal control of spinal cord functions. We have shown previously that transplantation below the level of the section of embryonic monoaminergic neurons can promote the recovery of some segmental functions via a local serotonergic and noradrenergic reinnervation. Moreover, the up-regulation of the corresponding receptors resulting from the section was corrected by the transplants. The aim of the present work was to determine whether such a graft could also influence non-monoaminergic local neurons, the GABAergic interneurons of the spinal cord. Following spinal cord transection, the number of cells which express glutamate decarboxylase (mol. wt 67,000) messenger RNA--a marker of GABA synthesis--increased significantly below the lesion compared with the intact animal. In contrast, in lesioned animals which had been grafted one week later with raphe neuroblasts, this number was close to control level. These post-grafting modifications were further associated with increased GABA immunoreactivity in the host tissue. These data suggest that the graft of embryonic raphe cells which compensates the deficit of serotonin in the distal segment also regulates the expression of the GABAergic phenotype in the host spinal cord. This regulation could be mediated by the re-establishment of a local functional innervation by both serotonin and GABAergic transplanted neurons and/or by trophic factors released from the embryonic cells. It appears then that grafted cells influence the host tissue in a complex manner, through the release and/or regulation of several neurotransmitter systems.
Dumoulin
A
A
INSERM Unité 336, Université Montpellier II, France.
Privat
A
A
Giménez y Ribotta
M
M
D000818:Animals; D017690:Cell Transplantation; D004622:Embryo, Mammalian / Q000166:cytology; D005260:Female; D016332:Fetal Tissue Transplantation; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007395:Interneurons / Q000502:physiology; D010641:Phenotype; D011903:Raphe Nuclei / Q000166:cytology / Q000196:embryology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000378:metabolism; D013119:Spinal Cord Injuries / Q000235:genetics / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D005680:gamma-Aminobutyric Acid