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Biphasic Response of Spinal GABAergic Neurons after a Lumbar Rhizotomy in the Adult Rat
Author(s) -
Dumoulin Andréa,
Alonso Gérard,
Privat Alain,
Feldblum Sophie
Publication year - 1996
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1996.tb01549.x
Subject(s) - gabaergic , glutamate decarboxylase , rhizotomy , immunostaining , spinal cord , neuroscience , biology , in situ hybridization , glial fibrillary acidic protein , immunohistochemistry , anatomy , pathology , inhibitory postsynaptic potential , medicine , messenger rna , immunology , biochemistry , gene , enzyme
The expression of γ‐aminobutyric acid (GABA) and of the isoforms of the enzyme involved in its synthesis, glutamic acid decarboxylase (GAD), is modified in several rat brain structures in different injury models. The aim of the present work was to determine whether such plasticity of the GABAergic system also occurred in the deafferented adult rat spinal cord, a model where a major reorganization of neural circuits takes place. GABAergic expression following unilateral dorsal rhizotomy was studied by means of non‐radioactive in situ hybridization to detect GADs 67 mRNA and by immunohistochemistry to detect GAD 67 protein and GABA. Three days following rhizotomy the number of GAD 67 mRNA‐expressing neurons was decreased in the superficial layers of the deafferented horn, while GABA immunostaining of axonal fibres located in this region was highly increased. Seven days after lesion, on the other hand, many GAD 67 mRNA‐expressing neurons were bilaterally detected in deep dorsal and ventral layers, this expression being correlated with the increased detection of GADs 67 immunostained somata and with the reduction of GABA immunostaining of axons. GABA immunostaining was frequently found to be associated with reactive astrocytes that exhibited intense immunostaining for glial fibrillary acidic protein (GFAP) but remained GADs 67 negative. These results indicate that degeneration of afferent terminals induces a biphasic response of GABAergic spinal neurons located in the dorsal horn and show that many spinal neurons located in deeper regions re‐express GAD 67 , suggesting a possible participation of the local GABAergic system in the reorganization of disturbed spinal networks.