[3H]muscimol binding of GABA receptors in the visual cortex of normal and monocularly deprived cats.

In vitro receptor binding techniques were used to compare the total number, affinity and regional distribution of GABA receptors in visual cortex, as revealed by [3H]muscimol binding, in 5 normal and 5 monocularly deprived (MD) cats. Analysis of saturation kinetics and pharmacological specificity indicated that binding was to a single site having the characteristics of the GABAA receptor. No differences were found between normal and MD cats in either number or affinity of receptors. Within visual cortex, there were laminar differences in the density of binding, but no evidence for a lateral (columnar) organization. Label was densest in the superficial layers (I-IV), lowest in layer V and intermediate in layer VI. This pattern of label varied with incubation parameters with layer IV showing the densest label when high concentrations of [3H]muscimol and short rinse times were used. There were no differences between normal and MD cats in regional distribution of receptors under any incubation condition.