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 fo llowing immunolabeling with an alpha(1)-subunit-specific antibody. alp ha(1)-Immunopositive striatal neurons are relatively scarce. Those loc ated in the dorsal striatum are small and have rounded somata and nume rous 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 poly gonal 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 spe cific for DARPP-32 (a cell-level indicator of dopamine D1-like recepto rs) and the alpha(1) antibody showed a complete lack of colocalization of these two markers in striatal neurons.