GABA(A) AND GABA(B) RECEPTORS DIFFERENTIALLY REGULATE STRIATAL ACETYLCHOLINE-RELEASE IN-VIVO

Microdialysis was used to study the effects of selective GABAergic age nts on striatal acetylcholine (ACh) release in awake, freely moving ra ts. Local perfusion with the GABA(A) agonist muscimol dramatically red uced striatal ACh release, while the GABA(B) agonist baclofen caused o nly minor decreases in ACh release. Co-perfusion with the GABA(A) anta gonist bicuculline diminished the muscimol-induced decrease in ACh rel ease. Likewise. co-perfusion with the GABA(B) antagonist 2-hydroxysacl ofen attenuated the baclofen-induced reduction in ACh release. Bicucul line alone markedly increased striatal ACh release, but 2-hydroxysaclo fen by itself had no effect. These results suggest that GABA tonically regulates striatal ACh release primarily through stimulation of inhib itory GABA(A) receptors.