DIFFERENTIAL SUBCELLULAR-DISTRIBUTION OF THE ALPHA-6 SUBUNIT VERSUS THE ALPHA-1 AND BETA-2/3 SUBUNITS OF THE GABAA/BENZODIAZEPINE RECEPTOR COMPLEX IN GRANULE CELLS OF THE CEREBELLAR CORTEX

The distribution of the alpha6 subunit of the GABA(A) receptor has been established in rat cerebellum and compared to the distribution of the alpha1 (cat) and the beta2/3 (rat, cat) subunits, using immunocytochemistry. The synapses established by Golgi cell terminals on the dendrites of granule cells were immunoreactive for the alpha6, alpha1 and beta2/3 subunits in virtually all glomeruli, indicating that two variants (alpha1 and alpha6) of the same subunit are co-localized at the same synapses. The somatic membranes of the granule cells, which receive no synapses, were immunopositive for the alpha1 and beta2/3 subunits, but not for the alpha6 subunit. Thus, the alpha1 and the beta2/3 subunits are located at both synaptic and extrasynaptic sites, but the alpha6 subunit is detectable only at synaptic sites.