Nitric Oxide (NO) Inhibites the Neuronal Activities in the Rat Nucleus Tractus Solitarius.
- Author:
Mi Won KIM
1
;
Mun Sung PARK
;
Sun Youl RYU
;
Ji Yeon JUNG
;
Yeon Jin JEONG
;
Sun Hun KIM
;
Min Seok KIM
;
Won Jae KIM
Author Information
1. Department of Oral Physiology, College of Dentistry, Dental Science Research Institute, Korea. wjkim@chonnam.ac.kr
- Publication Type:Original Article
- Keywords:
Nitric oxide;
Nucleus tractus solitarius
- MeSH:
Action Potentials;
Animals;
Fires;
Guanylate Cyclase;
Humans;
Immunohistochemistry;
Membrane Potentials;
Nervous System;
Neurons*;
NG-Nitroarginine Methyl Ester;
Nitric Oxide*;
Rats*;
Rats, Sprague-Dawley;
Solitary Nucleus*;
Tissue Donors
- From:The Korean Journal of Physiology and Pharmacology
2004;8(1):7-15
- CountryRepublic of Korea
- Language:English
-
Abstract:
Nitric oxide (NO) system has been implicated in a wide range of physiological functions in the nervous system. However, the roleof NO in regulating the neural activity in the gustatory zone of nucleus tractus solitarius (NTS) has not been established. The present study was aimed to investigate the role of NO in the gustatory NTS neurons. Sprague-Dawley rats, weighing about 50 g, were used. Whole cell patch recording and immunohistochemistry were done to determine the electrophysiological characteristics of the rostral gustatory nucleus of the tractus solitarius and distribution of NO synthases (NOS). Neuronal NOS (nNOS) immunoreactivity was strongly detected along the solitary tract extending from rostral to caudal medulla. Resting membrane potentials of NTS neurons were -49.2+/-2 mV and action potential amplitudes were 68.5+/-2 mV with a mean duration measured at half amplitude of 1.7+/-0.3 ms. Input resistance, determined from the response to a 150 ms, -100 pA hyperpolarizing current pulse, was 385+/-15 MOmega. Superfusion of SNAP or SNP, NO donors, produced either hyperpolarization (68%), depolarization (5%), or no effect (27%). The hyperpolarization was mostly accompanied by a decrease in input resistance. The hyperpolarization caused by SNAP or SNP increased the time to initiate the first action potential, and decreased the number of action potentials elicited by current injection. SNP or SNAP also markedly decreased the number of firing neural discharges of the spontaneous NTS neural activity under zero current. Superfusion of L-NAME, a NOS inhibitor, slightly depolarized the membrane potential and increased the firing rate of NTS neurons induced by current injection. ODQ, a soluble guanylate cyclase inhibitor, ameliorated the SNAP-induced changes in membrane potential, input resistance and firing rates. 8-Br-cGMP, a non-degradable cell-permeable cGMP, hyperpolarized the membrane potential and decreased the number of action potentials. It is suggested that NO in the gustatory NTS has an inhibitory role on the neural activity of NTS through activating soluble guanylate cyclase.
