3H-muscimol binding in synaptosomal fractions from bovine and developing rabbit retinas.

Bovine and rabbit retina synaptosomal fractions bind the potent and specific GABA agonist, [3H]-muscimol with high affinity and limited capacity. The high degree of pharmacological specificity and the subcellular distribution of these binding sites are similar to those reported for [3H]-GABA binding sites. These observations suggest that these sites represent the recognition sites for GABA receptors. The specific binding of [3H]-muscimol in retinal homogenates from different aged rabbits reveal a distinct developmental profile with a fivefold to six fold increase in binding between days 5 and 13. Thus, it appears that GABA receptor development continues after eye opening in rabbits (day 9-10) and that receptor maturation is delayed by at least two to three days with respect to published of GABA uptake and evoked release.