Size and shape of glycine receptor clusters in a central neuron exhibit a somato-dendritic gradient.

The overall surface disposition of receptors for the neurotransmitter glycine was examined in situ on the teleost Mauthner cell. For this purpose, a monoclonal antibody specific for the glycine receptor was used in immunofluorescence experiments in association with the technique of confocal microscopy. Previous work had shown that on the Mauthner cell and other neurons, receptors for this transmitter are concentrated in discrete microdomains apposed to single presynaptic terminals. We now report that the size and the shape of these clusters depend on their cellular location, that is, their area increases regularly from the soma to the tip of the dendrites. Conversely, the number of clusters per unit area declines so that the final proportion of immunoreactive membrane remains constant at any portion of the cell. These results raise the question of the functional consequences of such an organized subcellular distribution of receptors.