GABA(A) receptor alpha(1)-subunit-immunopositive neurons in the rat striatum

The morphological characteristics and distribution of striatal neurons expressing the GABA(A) receptor alpha(1)-subunit were investigated following immunolabeling with an alpha(1)-subunit-specific antibody. alpha(1)-Immunopositive striatal neurons are relatively scarce. Those located in the dorsal striatum are small and have rounded somata and numerous dendrite varicosities. alpha(1)-Immunoreactive neurons with these characteristics were likewise observed in the ventral striatum, which also contained large pyramidal neurons with smooth dendrites and polygonal neurons with spiny dendrites. A fourth neuron type (oval neurons with dendrites oriented in bipolar fashion) was found in the lateral striatum. All four neuron types were observed in the rostral, central and caudal striatum. Double-labeling experiments using an antibody specific for DARPP-32 (a cell-level indicator of dopamine D1-like receptors) and the alpha(1) antibody showed a complete lack of colocalization of these two markers in striatal neurons.