Activation of non-NMDA receptors stimulates acetylcholine and GABA release from dorsal hippocampus: a microdialysis study in the rat.
The effect of the non-N-methyl-D-aspartate (NMDA) agonists (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and quisqualate (QUIS) on the release of acetylcholine (ACh), gamma-amino butyric acid (GABA), aspartate (Asp) and glutamate (Glu) from the hippocampus of freely moving rats was studied by transversal microdialysis. Intracerebroventricular (i.c.v.) administration of the non-NMDA receptor agonist AMPA (0.5 nmol) enhanced (by about 200%) ACh release from the hippocampus. The effect of AMPA was completely antagonized by 6-nitro-7-sulphamoyl-benz(f)quinoxaline-2,3-dione (NBQX; 2 nmol, i.c.v). No effect was seen when AMPA was perfused through the septum. However, AMPA (200 microM) locally applied to the hippocampus, increased (by about 200%) ACh release. QUIS (200 microM) applied locally to the hippocampus produced a long-lasting increase in the release of ACh (by about 215%) and GABA (by about 460%). Local infusion of tetrodotoxin (1 microM) decreased ACh and GABA basal extracellular levels, and abolished the QUIS-induced increase in ACh and GABA. Our results demonstrate that non-NMDA glutamatergic receptors in the hippocampus regulate hippocampal release of GABA and ACh.
Giovannini
M G
MG
Department of Preclinical and Clinical Pharmacology, University of Florence, Italy.
Rakovska
A
A
Della Corte
L
L
Bianchi
L
L
Pepeu
G
G
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D016202:N-Methylaspartate / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D016318:Quisqualic Acid / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; D018091:Receptors, AMPA; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D016318:Quisqualic Acid; D000109:Acetylcholine