Endothelin-1 increases the neuronal activity and augments the responses to glutamate in the NTS.
The aims of this study were to determine 1) whether endothelin (ET)-1 affects the neuronal activity of the NTS neurons, 2) whether specific ET receptor antagonists affect the neuronal activity of the NTS neurons, and 3) whether ET-1 or ET receptor antagonists modulate the responses of the nucleus of the solitary tract (NTS) neurons to L-glutamate (Glu). The single-unit discharge was extracellularly recorded with a fine electrode from medulla brain slice preparations of rats. ET-1 and Glu were iontophoretically applied to the recorded neuron. Both ET-1 and Glu increased the neuronal activity. The ETA receptor antagonist BQ-123 attenuated the basal neuronal activity. ET-1 augmented the magnitude of the increases in the neuronal activity evoked by Glu, and these responses were antagonized by BQ-123. These studies suggest the following conclusions: 1) ET-1 increases the neuronal activity of the NTS neurons via ETA receptors, 2) endogenous ET plays a controlling role of the neuronal activity of NTS neurons, and 3) ET-1 augments the responses evoked by Glu, believed to be the neurotransmitter from the solitary tract, via ETA receptors. These results suggest that ET-1 facilitates synaptic transmission in the NTS.
Shihara
M
M
Research Institute of Angiocardiology and Cardiovascular Clinic, Fukuoka 812-8582, Japan.
Hirooka
Y
Y
Hori
N
N
Matsuo
I
I
Tagawa
T
T
Suzuki
S
S
Akaike
N
N
Takeshita
A
A
D000818:Animals; D001931:Brain Mapping; D004357:Drug Synergism; D004558:Electric Stimulation; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000494:pharmacology* / Q000502:physiology*; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000494:pharmacology*; D066298:In Vitro Techniques; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D017552:Solitary Nucleus / Q000187:drug effects / Q000502:physiology*
D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D009842:Oligopeptides; D010456:Peptides, Cyclic; D010880:Piperidines; D018698:Glutamic Acid; C086539:BQ 788; C072247:cyclo(Trp-Asp-Pro-Val-Leu)