title: Modulation of in vivo GABA-evoked responses by nitric oxide-active compounds in the globus pallidus of rat.
abstract: Nitric oxide (NO) is a gaseous molecule acting as a messenger in both the peripheral and the central nervous systems. NO affects synaptic activity by modulating neurotransmitter release and/or receptor function. We previously observed that NO-active compounds modify the bioelectric activity of basal ganglia (BG) units. In this study, we applied microiontophoresis to extracellular in vivo recordings to investigate the effect of NO-active compounds on GABA-evoked responses in the globus pallidus (GP) of anesthetized rats. The changes induced by NO-active drugs on the GABA-induced inhibition were used as indicators of NO modulation. The response to GABA release was tested on recorded GP neurons before and during the administration of S-nitroso-glutathione (SNOG, a NO donor) and/or Nω-nitro-L: -arginine methyl ester (L: -NAME), an inhibitor of nitric oxide synthase (NOS); furthermore, SNOG and L: -NAME were tested at different ejection currents in order to highlight the possibility of a current-dependent effect in the nitrergic modulation of GABA transmission. In general, during SNOG ejection the magnitude of GABA-evoked responses was reduced, whereas the administration of L: -NAME produced the opposite effect. The results suggest that NO-active drugs modulate the response of GP neurons to GABA transmission; the effects induced by SNOG and L: -NAME were strictly related to the ejection currents. Then, the modulation of GABAergic transmission by NO could represent a mechanism to finely regulate the GP neurons activity with important consequences on the overall BG function.
authors.affiliation: Dipartimento di Bio-Medicina sperimentale e Neuroscienze cliniche, Sezione di Fisiologia umana G. Pagano, Università degli Studi di Palermo, Corso Tukory 129, Palermo, Italy. bio.carletti@unipa.it
authors.forename: Fabio
authors.initials: F
authors.lastname: Carletti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ferraro
authors.forename: Valerio
authors.initials: V
authors.lastname: Rizzo
authors.forename: Simonetta
authors.initials: S
authors.lastname: Friscia
authors.forename: Pierangelo
authors.initials: P
authors.lastname: Sardo
mesh_terms: D000818:Animals; D004594:Electrophysiology; D005071:Evoked Potentials / Q000502:physiology; D005917:Globus Pallidus / Q000378:metabolism*; D007478:Iontophoresis; D008297:Male; D009474:Neurons / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D009569:Nitric Oxide; D005680:gamma-Aminobutyric Acid