Nitric oxide modulates in vitro intrinsic optical signal and neural activity in the nucleus tractus solitarius of the rat.
Nitric oxide (NO) is a novel neurotransmitter with important cardiorespiratory functions. To determine the functional topography of NO in a brainstem preparation, extracellular and intrinsic optical signal recordings were simultaneously acquired from a 300 microm coronal brainstem slice at the level of the obex. During control conditions, spontaneous spike activity in the nucleus tractus solitarius (NTS) was 6.2 +/- 1.4 Hz. When the competitive NOS inhibitor, L-NAME, was applied to the bath (1 mM), spike activity either ceased or was markedly reduced in frequency (1.2 +/- 0.7 Hz; n = 7; P < 0.01). The decrease in activity was reversed when the NOS substrate L-arginine (L-Arg) was added to the bath (9.4 +/- 1.8 Hz; P < 0.04). Concurrent intrinsic optical signal imaging of the slice preparation consistently revealed coincident decreases in activity within the NTS with L-NAME (deltaT/T: -2.4 +/- 0.9%; P < 0.02), and increases with L-Arg (+2.1 +/- 0.8%; P < 0.04). Such changes were absent in other regions such as the hypoglossal nuclei or area postrema. We conclude that in this brainstem region, NO modulation of neuronal activity is primarily circumscribed to the NTS.
Torres
J E
JE
Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA.
Kreisman
N R
NR
Gozal
D
D
D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D009569:Nitric Oxide / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017552:Solitary Nucleus / Q000187:drug effects*
D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester