Article date: 1986/1/1
PubMed ID: 2844060
Journal name: International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience (ISSN: 0736-5748)
The temporal course of the development of GABA receptor sites in chick optic lobe was studied as a parameter of neuronal differentiation in the central nervous system. At 10 days of incubation, specific [3H]GABA binding was of 0.08 pmol/optic lobe and increased 7-8 fold between 12 and 16 days of incubation, reaching at 16 days a value of 0.60 pmol/optic lobe. This coincides with the period of arrival of the retinal fibers to the optic lobe. After this stage, the number of GABA binding sites decreased to a value of 0.35 pmol/optic lobe at hatching. After hatching a new increase appeared which reached at 5 days post-hatching a value of 0.87 pmol/optic lobe. Scatchard analysis of the saturation binding data obtained at 16 days of incubation and at hatching revealed the presence of two binding sites: one with high affinity and the other with low affinity, while at 12 days of incubation, the earliest stage examined, only the low-affinity binding site appeared. The high-affinity binding site for [3H]GABA was inhibited by muscimol, GABA, and bicuculline (IC50: 0.006, 0.002 and 10 microM, respectively). These values correspond to the potencies shown by those compounds in the binding to the synaptic GABA receptor. Treatment of the synaptic membranes with Triton X-100 showed a marked increase in the amount of specific [3H]GABA binding after 16 days of incubation reaching a 3-fold increase at hatching. These results suggest that endogenous inhibitors of the higher affinity binding site, probably appear during this period.
Author List: Flores V, Rios H, Fiszer de Plazas S
Publication Types: Journal Article; Research Support, Non-U.S. Gov't
Substances mentioned in the article: Nerve Tissue Proteins; Receptors, GABA-A; Polyethylene Glycols; Octoxynol;
Mesh terms: Animals; Chick Embryo/drug effects; Nerve Tissue Proteins/metabolism; Octoxynol; Optic Lobe, Nonmammalian/drug effects; Polyethylene Glycols/pharmacology; Receptors, GABA-A/drug effects;