Presynaptic α2-adrenoceptors inhibit excitatory synaptic transmission in rat brain stem

Makia Bertolino, Stefano Vicini, Richard Gillis, Renato Alberto Travagli

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

The synaptic connection between the commissural portion of the nucleus tractus solitarius (ComNTS) and the dorsal motor nucleus of the vagus (DMV) was studied in rat brain stem slices, using the patch-clamp technique. The excitatory postsynaptic currents (EPSC) evoked by stimulation of the ComNTS were blocked by kynurenic acid (1 mM) and, in Mg2+-free solution, were sensitive to both the N-methyl-D-aspartic acid (NMDA) receptor blocker 3- [(RS)-2-carboxypiperazine-4-yl]-propyl-1-phosphonic acid (20 μM) and the non-NMDA receptor blocker 2,3-dihydro-6-nitro-7-sulfamoyl- benzo(f)quinoxaline (5 μM). Norepinephrine (NE, 1-100 μM) inhibited the EPSC, and the inhibition was attenuated by the α2-adrenoceptor antagonists idazoxan (1 μM) and yohimbine (10 μM) but not by the β-adrenoceptor antagonist nadolol (50 μM). The NE-releasing agent tyramine (100 μM) reduced the EPSC, and the inhibition was attenuated by 1 μM idazoxan. NE (30 μM) did not affect the membrane input resistance but reduced the paired- pulse depression, demonstrating that NE acts on presynaptic α2- adrenoceptors. The results indicate the existence of a glutamatergic pathway from the ComNTS to the DMV neurons modulated by presynaptic NE receptors. This pathway might be a component of the vagovagal reflex regulating gastrointestinal function.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume272
Issue number3 35-3
StatePublished - Mar 1 1997

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Solitary Nucleus
Excitatory Postsynaptic Potentials
Synaptic Transmission
Adrenergic Receptors
Idazoxan
Brain Stem
Nadolol
Kynurenic Acid
Presynaptic Receptors
D-Aspartic Acid
Tyramine
Yohimbine
Patch-Clamp Techniques
N-Methylaspartate
Reflex
Norepinephrine
Depression
Neurons
Membranes
aspartic acid receptor

All Science Journal Classification (ASJC) codes

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

Cite this

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abstract = "The synaptic connection between the commissural portion of the nucleus tractus solitarius (ComNTS) and the dorsal motor nucleus of the vagus (DMV) was studied in rat brain stem slices, using the patch-clamp technique. The excitatory postsynaptic currents (EPSC) evoked by stimulation of the ComNTS were blocked by kynurenic acid (1 mM) and, in Mg2+-free solution, were sensitive to both the N-methyl-D-aspartic acid (NMDA) receptor blocker 3- [(RS)-2-carboxypiperazine-4-yl]-propyl-1-phosphonic acid (20 μM) and the non-NMDA receptor blocker 2,3-dihydro-6-nitro-7-sulfamoyl- benzo(f)quinoxaline (5 μM). Norepinephrine (NE, 1-100 μM) inhibited the EPSC, and the inhibition was attenuated by the α2-adrenoceptor antagonists idazoxan (1 μM) and yohimbine (10 μM) but not by the β-adrenoceptor antagonist nadolol (50 μM). The NE-releasing agent tyramine (100 μM) reduced the EPSC, and the inhibition was attenuated by 1 μM idazoxan. NE (30 μM) did not affect the membrane input resistance but reduced the paired- pulse depression, demonstrating that NE acts on presynaptic α2- adrenoceptors. The results indicate the existence of a glutamatergic pathway from the ComNTS to the DMV neurons modulated by presynaptic NE receptors. This pathway might be a component of the vagovagal reflex regulating gastrointestinal function.",
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Presynaptic α2-adrenoceptors inhibit excitatory synaptic transmission in rat brain stem. / Bertolino, Makia; Vicini, Stefano; Gillis, Richard; Travagli, Renato Alberto.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 272, No. 3 35-3, 01.03.1997.

Research output: Contribution to journalArticle

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