GABA(A) ANTAGONISTS REVEAL BINDING-SITES FOR [S-35] TBPS IN CEREBELLAR GRANULAR-CELL LAYER

Autoradiography revealed picrotoxin-sensitive [S-35]TBPS ([S-35]t-butylbicyclophosphorothionate) binding sites in the cerebellar granule cell layer only in the presence of GABA(A) receptor antagonists. However, under the same conditions, the binding was decreased in other brain regions, including the cerebellar molecular cell layer. Thus, the convulsant binding sites at GABA(A) receptors in the granule cell layer are highly sensitive to down-regulation by GABA, which may be due to a unique combination of receptor subunits.