title: Distribution of GAD-like immunoreactivity in the retina and central visual system of Rana pipiens.
abstract: Immunohistochemistry was used to survey the distribution of glutamic acid decarboxylase (GAD), the synthesizing enzyme for gamma-aminobutyric acid (GABA), throughout the visual system of the frog Rana pipiens. GAD-like immunoreactivity (GAD-LI) was assessed in the retina, in primary retinorecipient targets, and in thalamic nuclear groups postsynaptic to primary retinal terminal zones. Within the retina, the inner plexiform layer displayed intense GAD-LI, but immunoreactivity was absent in the ganglion cell layer (GCL). Putative amacrine, bipolar, and horizontal cell somata were also labeled. Centrally, GAD-LI was observed in all primary visual nuclei. Dense, GAD-like immunoreactive punctate structures (puncta), presumably terminals, were observed in the pretectal nucleus lentiformis mesencephali, posterior thalamic neuropil, and uncinate neuropil. GAD-like immunoreactive puncta were noted in several laminae of the optic tectum, with the highest concentrations located within the 9th and 8th laminae. Moderate numbers of GAD-like immunoreactive puncta were found in the mesencephalic nucleus of the basal optic root, and two thalamic neuropils--corpus geniculatum and neuropil of Bellonci. The ventrolateral area, posterocentral nucleus, and posterolateral nucleus all contained sparse amounts of GAD-LI. These observations suggest that GABA plays an important physiological role in all central visual areas of Rana pipiens.
authors.affiliation: Neuroscience and Behavior Program, University of Massachusetts, Amherst 01003-7710, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Tyler
authors.forename: K V
authors.initials: KV
authors.lastname: Fite
authors.forename: G J
authors.initials: GJ
authors.lastname: Devries
mesh_terms: D000818:Animals; D005968:Glutamate Decarboxylase / Q000276:immunology*; D007150:Immunohistochemistry; D009900:Optic Nerve; D011894:Rana pipiens; D012160:Retina / Q000502:physiology*; D013788:Thalamus; D014795:Visual Pathways / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology
chemical_list: D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase