The discharge of subthalamic neurons is modulated by inhibiting the nitric oxide synthase in the rat.
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.
Sardo
Pierangelo
P
Dipartimento di Medicina Sperimentale - Sezione di Fisiologia umana, Università degli Studi di Palermo, Corso Tukory, 129, Palermo 90134, Italy. pierangelo.sardo@unipa.it
Ferraro
Giuseppe
G
Carletti
Fabio
F
D'Agostino
Stefania
S
La Grutta
Vittorio
V
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
D004791:Enzyme Inhibitors; D007191:Indazoles; D019001:Nitric Oxide Synthase; C080122:7-nitroindazole; D019331:NG-Nitroarginine Methyl Ester