title: The discharge of subthalamic neurons is modulated by inhibiting the nitric oxide synthase in the rat.
abstract: The effects induced on the discharge of subthalamic spontaneously active neurons by inhibiting the enzyme nitric oxide synthase was studied in two groups of urethane-anesthetized rats. In the first group of animals (n = 10), the activity of subthalamic single units was recorded before and after the systemic administration of 7-nitro-indazole (7-NI, 50 mg/kg i.p.), a selective inhibitor of neuronal nitric oxide synthase. In the second group of rats (n = 15), Nomega-nitro-L-arginine methyl ester (L-NAME), another inhibitor of nitric oxide synthase, was iontophoretically administered while performing single unit extracellular recordings. The activity of most tested spontaneously discharging neurons (8/10) was influenced by 7-NI administration, which always caused a statistically significant decrease in the firing rate of the responsive cells. In contrast, the iontophoretic administration of L-NAME, although influencing many cells (24/32), did not have univocal effects: in fact, 18 cells were inhibited while 6 neurons were excited in a statistically significant manner. We hypothesize that nitric oxide neurotransmission could exert a tonic modulatory influence upon spontaneously discharging subthalamic neurons, with a prevalent excitatory effect.
authors.affiliation: Dipartimento di Medicina Sperimentale - Sezione di Fisiologia umana, Università degli Studi di Palermo, Corso Tukory, 129, Palermo 90134, Italy. pierangelo.sardo@unipa.it
authors.forename: Pierangelo
authors.initials: P
authors.lastname: Sardo
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ferraro
authors.forename: Fabio
authors.initials: F
authors.lastname: Carletti
authors.forename: Stefania
authors.initials: S
authors.lastname: D'Agostino
authors.forename: Vittorio
authors.initials: V
authors.lastname: La Grutta
mesh_terms: D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007191:Indazoles / Q000494:pharmacology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D020530:Subthalamus / Q000166:cytology*; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D007191:Indazoles; D019001:Nitric Oxide Synthase; C080122:7-nitroindazole; D019331:NG-Nitroarginine Methyl Ester