GABAA receptor-like immunoreactivity in the goldfish brainstem with emphasis on the Mauthner cell.
The distribution of the GABAA receptor in the goldfish brainstem and on the Mauthner cell membrane was investigated with both optical and electron microscopy using a polyclonal antibody raised against the intracellular loop of the rat gamma 2 subunit. At the optical level, immunofluorescent dots were detected on small and large neurons belonging to vestibular and reticular nuclei. On the Mauthner cell plasmalemma, a gamma 2-like immunoreactivity was observed predominantly on the tip of the lateral dendrite. Fluorescent parches were intermingled with a more diffuse staining. Immunoreactive spots of weaker intensity were also present on the soma and some were also observed inside and within the periphery of the axon-cap as well. Observations at the electron microscopic level revealed that the peroxidase end-product predominates postsynaptically in front of release sites in the studied nuclei and on the Mauthner cell. On the lateral dendrite of the neuron, numerous immunopositive postsynaptic differentiations were encountered on spines. Stained glial elements were encountered in the different areas studied. These results demonstrate that the GABAA receptor gamma 2 subunit has a precise distribution on neuronal membranes and suggest that it could be involved in the remote dendritic inhibition of the Mauthner cell and in the control of input-output properties of both vestibular and reticular nuclei.
Sur
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Laboratoire de Neurobiologie Cellulaire (INSERM U261), Département des Biotechnologies, Institut Pasteur, Paris, France.
McKernan
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R
Triller
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A
D000818:Animals; D001933:Brain Stem / Q000166:cytology*; D002462:Cell Membrane / Q000648:ultrastructure; D003712:Dendrites / Q000648:ultrastructure; D006054:Goldfish; D007150:Immunohistochemistry; D046911:Macromolecular Substances; D016253:Microscopy, Immunoelectron; D009474:Neurons / Q000166:cytology* / Q000648:ultrastructure; D011963:Receptors, GABA-A / Q000032:analysis*; D018009:Receptors, Glycine / Q000032:analysis; D013569:Synapses / Q000648:ultrastructure*
D046911:Macromolecular Substances; D011963:Receptors, GABA-A; D018009:Receptors, Glycine