Colocalization of GABA, glycine, and their receptors at synapses in the rat spinal cord

Abstract

To determine whether GABA and glycine can act as cotransmitters at synapses in the rat spinal cord, we have compared the ultrastructural distribution of GABAA-receptor beta 3 subunit with that of the glycine receptor-associated protein gephyrin and combined this with postembedding detection of GABA and glycine. We also used a dual-immunofluorescence method to confirm that gephyrin was associated with the glycine-receptor alpha 1 subunit throughout the cord. GABAA beta 3-subunit immunoreactivity was restricted primarily to synapses, and at a majority of these synapses the presynaptic axon was GABA-immunoreactive. Many synapses showed both GABAA beta 3 and gephyrin immunoreactivity, and at most of these synapses GABA and glycine were enriched in the presynaptic axon. These results strongly support the idea that cotransmission by GABA and glycine occurs in the spinal cord.

GABAAReceptor Subunit Composition and Functional Properties of Cl−Channels with Differential Sensitivity to Zolpidem in Embryonic Rat Hippocampal Cells

“…and rabbit polyclonal antibodies specific for ␣1 (1-9 residues), ␣4 (379 -421 residues), ␣5 (2-10 residues), ␤1 (350 -404 residues), ␤2 (351-405 residues), ␤3 (345-408 residues), ␥1 (324 -366 residues), ␥2 (319 -366 residues), and ␥3 (322-372 residues) subunits (generated by W.S.). The characterization and specificity of these antibodies have been described in detail elsewhere (Benke et al, 1991(Benke et al, , 1997Buchstaller et al, 1991;Marksitzer et al, 1993;Mertens et al, 1993;Mossier et al, 1994;Todd et al, 1996;Sperk et al, 1997). The cells were immunoreacted with guinea pig antibodies diluted 1:1000 or rabbit antibodies diluted 1:100 -300 overnight at room temperature.…”

The γ-aminobutyric acid type A (GABA A ) receptor-associated protein (GABARAP) promotes GABA A receptor clustering and modulates the channel kinetics

“…Decreased GABA A receptor clustering results in dysfunction of GABA A receptors at the cellular level and anxiety disorders at the animal level (4). Gephyrin was reported to colocalize with GABA A receptor at synaptic sites in retina and spinal cord (5,6). In GABA A receptor ␥2 subunit knockout mice, clusters of GABA A receptors were decreased greatly, and most of the gephyrin staining was also gone (7).…”

GABA‐, glycine‐, and glutamate‐immunoreactive bouton profiles in apposition to neurons of the central cervical nucleus in the rat

“…In the spinal cord, there is a high degree of colocalization of glycine and GABA in neurons (Todd, 1996;Todd and Sullivan, 1990;Todd et al, 1996;Shupliakov et al, 1993;Ö rnung et al, 1996), and a matching codistribution of glycine and GABA receptors has been observed in many neurons of the spinal cord (Bohlhalter et al, 1994;Todd et al, 1996). There is evidence for a co-release of glycine and GABA, for example at the Renshaw-motoneuron synapses (e.g., Cullheim and Kellerth, 1981).…”