Distinct presynaptic regulation of dopamine release through NMDA receptors in striosome- and matrix-enriched areas of the rat striatum

Abstract

Striosome- and matrix-enriched striatal zones were defined in coronal and sagittal brain sections of the rat, on the basis of 3H-naloxone binding to μ-opiate receptors (a striosomespecific marker). Then, using a new in vitro microsuperfusion device, the NMDA (50 μM)-evoked release of newly synthesized 3H-dopamine (3H-DA) was examined in these four striatal areas under Mg2+-free conditions. The amplitudes of the responses were different in striosomal (171 ± 6% and 161 ± 5% of the spontaneous release) than in matrix areas (223 ± 6% and 248 ± 12%), even when glycine (1 or 100 μM) was coapplied (in the presence of 1 MM strychnine). In the four areas, the NMDA-evoked release of 3H-DA was blocked completely by Mg2+ (1 mM) or (+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine maleate (MK-801; 1 μM) and almost totally abolished by kynurenate (100 μM). Because the tetrodotoxin (TTX)-resistant NMDA-evoked release of 3H-DA was similar in Striosome- ( 148 ± 5 % and 152 ± 6%) or matrix-enriched (161 ± 5% and 156 ± 7%) areas, the indirect (TTX-sensitive) component of NMDA-evoked responses, which involves striatal neurons and/or afferent fibers, seems more important in the matrix- than in the striosome-enriched areas. The modulation of DA release by cortical glutamate and/or aspartate-containing inputs through NMDA receptors in the matrix appears thus to be partly distinct from that observed in the striosomes, providing some functional basis for the histochemical striatal heterogeneity. Copyright © 1991 Society for Neuroscience.