Modulation of acetylcholine release via GABA A and GABA B receptors in rat striatum

Abstract

In order to investigate whether changes in acetylcholine (ACh) release induced by GABA receptors are due to a direct or indirect effect on cholinergic neurons in the striatum, GABA A and GABA B receptor bindings were assayed in the striatum microinjected with ethylcholine mustard aziridinium ion (AF64A), a cholinergic neurotoxin. Intra-striatal injection of a selective concentration of AF64A (10 nmol) reduced GABA A receptor binding without significantly altering GABA B receptor binding. Treatment with a higher, less selective concentration of AF64A (20 nmol) reduced all markers examined. These results suggest that GABA A, but not GABA B receptors, are located on cholinergic neurons in the striatum, and that GABA can directly modulate ACh release through stimulation of GABA A receptors. Findings further suggest that GABA can also indirectly modulate ACh release through stimulation of GABA B receptors located on non-cholinergic neuronal elements in the striatum.