Abstract
Purpose: :
Recently, it was proposed that OFF ganglion cells receive a direct inhibitory input from AII amacrine cells. This pathway provides a disinhibitory input at low contrast (Manookin et al., 2008). In addition, -like ganglion cells in the mouse retina express kinetically fast glycine receptors composed of 1 subunits (Majumdar et al., 2007). Here, we provide anatomical evidence in support of lobular AII contacts via glycine 1 receptors with OFF ganglion cells.
Methods: :
OFF ganglion cells in wholemount rabbit retina were dye injected with Neurobiotin. After fixation, the AII amacrine cell population was labeled with an antibody against calretinin and glycine receptors were marked with an antibody against the 1 subunit. These materials were analyzed by triple-label confocal microscopy.
Results: :
OFF ganglion cells showed the typical dendritic morphology. They were stratified in sublamina a and dye-coupled to other OFF ganglion cells and unidentified amacrine cells. The lobules of AII amacrine cells made close contacts at many points along the dendrites of individual OFF ganglion cells. At these potential synaptic sites, we also found punctate labeling for the glycine 1 subunit.
Keywords: ganglion cells • amacrine cells • retina