α5 Subunit-containing GABAA receptors form clusters at GABAergic synapses in hippocampal cultures

We have used triple-label fluorescence immunocytochemistry to demonstrate that as subunit-containing GABA(A) receptors (GA-BA(A)Rs) form large clusters at GABAergic synapses in dendrites and axon initial segment of cultured hippocampal neurons. The large synaptic clusters of alpha(5) subunit-containing GABA(A)Rs also contained alpha(1), beta(2/3), gamma(2) GABA(A)R subunits and gephyrin. The alpha(5) subunit-containing GABA(A)Rs also formed small clusters. The small clusters were not associated with GABAergic synapses and often did not co-localize with gephyrin.