Glycine in the lizard retina: comparison to the GABA system.
Neurons likely to utilize glycine (GLY) as a neurotransmitter were identified immunocytochemically in the "all-cone" lizard retina and the basic anatomical organization of the retinal GLY and gamma-aminobutyric acid (GABA) systems was compared. Four types of GLY-immunoreactive (GLY-IR) neurons were identified. Most GLY-IR cells were amacrine cells, which comprised at least two types. GLY-IR interplexiform cells and ganglion cells also were identified. The first GLY-IR amacrine cell type was characterized by a small pyriform soma, located distal to the border of the inner plexiform layer (IPL), and fine dendrites. Most GLY-IR amacrine cells were of this type and several subtypes may exist within this group. The second amacrine cell type was characterized by a large, distally located soma and a large descending process. This amacrine cell type showed colocalization of GLY-IR and GABA-IR and comprised about 4% of the total GLY-IR amacrine cell population. Comparison of GLY-IR and GABA-IR on serial sections showed that GLY and GABA were present in largely separate neuronal populations. Generally, GLY-IR amacrine cells were smaller, more distally located in the inner nuclear layer and had finer dendrites than GABA-IR amacrine cells. Distribution of GLY-IR and GABA-IR in the outer plexiform layer and the inner plexiform layer differed considerably. Based on the segregated distribution of GLY-IR and GABA-IR in the synaptic layers of the lizard retina, GLY and GABA may have fundamentally different roles in retinal processing.
Sherry
D M
DM
Department of Neurobiology and Behavior, SUNY-Stony Brook.
Micich
A
A
Yazulla
S
S
D000818:Animals; D005455:Fluorescent Antibody Technique; D005998:Glycine / Q000032:analysis*; D007091:Image Processing, Computer-Assisted; D008116:Lizards; D009474:Neurons / Q000737:chemistry; D012160:Retina / Q000737:chemistry*; D012165:Retinal Ganglion Cells / Q000737:chemistry; D016622:Silver Staining; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
D005680:gamma-Aminobutyric Acid; D005998:Glycine