title: Endogenous nitric oxide facilitates striatal dopamine and glutamate efflux in vivo: role of ionotropic glutamate receptor-dependent mechanisms.
abstract: We have investigated the influence of the nitric oxide synthase (NOS) substrate, NG-hydroxy-L-arginine (H-ARG) on dopamine (DA) and glutamate (GLU) efflux in vivo using concentric microdialysis probes implanted in the anterior-medial striatum of chloral hydrate-anesthetized rats. Intrastriatal infusion of H-ARG (100 microM, 200 microM, or 1 mM for 120 min) increased DA efflux in a dose-dependent fashion. The facilitatory effect of H-ARG (1 mM) on DA efflux was abolished following pretreatment (80 min) with the constitutive NOS inhibitor 7-nitroindazole (7-NI, 10 microM) but unaffected by L-NG(1-iminoethyl) lysine (100 microM) infusion. As both H-ARG (1 mM) and the NO-generator (+/-)-S-nitroso-N-acetylpenicillamine (1 mM) were observed to increase GLU efflux concurrently with the effect on DA efflux, we evaluated the potential intermediary role of GLU in NO-facilitated DA efflux using ionotropic GLU receptor antagonists. Local infusion of dizocilpine maleate (10 microM) or (+/-)-2-amino-3-[3-(carboxymethoxy)-5-methyl-isoxazol-4-yl] propionic acid (100 microM), attenuated the H-ARG (1 mM)-induced elevation of extracellular DA levels. Conversely, similar treatment with the kainate receptor antagonist d-gamma-glutamyl-aminomethanesulfonic acid did not alter H-ARG-induced DA efflux. To evaluate the regulatory influence of striatal NO on NMDA receptor activation, NMDA (100 microM) was co-perfused with either H-ARG (2 mM) or 7-NI (10 microM). While co-perfusion with 7-NI potentiated NMDA-induced DA efflux, similar treatment with H-ARG (2 mM) abolished the effect. These results demonstrate that endogenous NO production, stimulated via H-ARG-dependent activation of type 1 NOS, enhances striatal DA efflux via an increase in glutamatergic tone on ionotropic GLU-receptors. At higher levels of NOS activation (following H-ARG (2 mM) or NMDA infusion), NO may block glutamatergic neurotransmission via inhibition of NMDA receptor function.
authors.forename: A R
authors.initials: AR
authors.lastname: West
authors.forename: M P
authors.initials: MP
authors.lastname: Galloway
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004298:Dopamine / Q000378:metabolism*; D004563:Electrochemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D017551:Microdialysis; D017072:Neostriatum / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052248:Nitric Oxide Synthase Type I; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017470:Receptors, Glutamate / Q000187:drug effects / Q000378:metabolism*; D026423:S-Nitroso-N-Acetylpenicillamine
chemical_list: D004791:Enzyme Inhibitors; D017470:Receptors, Glutamate; D009569:Nitric Oxide; D018698:Glutamic Acid; C068309:N(omega)-hydroxyarginine; D026423:S-Nitroso-N-Acetylpenicillamine; D001120:Arginine; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D010396:Penicillamine; D004298:Dopamine