Dopamine effects on identified rat vagal motoneurons

Zhongling Zheng, Renato Alberto Travagli

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Catecholaminergic neurons of the A2 area play a prominent role in brain stem vagal circuits. It is not clear, however, whether these neurons are noradrenergic or adrenergic, i.e., display tyrosine hydroxylase (TH) and dopamine-β-hydroxylase (DβH) immunoreactivity (-IR) or dopaminergic (i.e., TH- but not DβH-IR). Our aims were to investigate whether a subpopulation of neurons in the A2 area was dopaminergic and, if so, to investigate the effects of dopamine (DA) on the membrane of gastric-projecting vagal motoneurons. We observed that although the majority of A2 neurons were both TH- and DβH-IR, a small percentage of nucleus tractus solitarius neurons were TH-IR only, suggesting that DA itself may play role in these circuits. Whole cell recordings from thin brain stem slices showed that 71% of identified gastric-projecting motoneurons responded to DA (1-300 μM) with either an excitation (28%) or an inhibition (43%) of the membrane; the remaining 29% of the neurons were unresponsive. The DA-induced depolarization was mimicked by SK 38393 and prevented by pretreatment with SCH 23390. Conversely, the DA-induced inhibition was mimicked by bromoergocryptine and prevented by pretreatment with L741626. When tested on the same neuron, the effects of DA and NE were not always similar. In fact, in neurons in which DA induced a membrane depolarization, 77% were inhibited by NE, whereas 75% of neurons unresponsive to DA were inhibited by NE. Our data suggest that DA modulates the membrane properties of gastric-projecting motoneurons via D1- and D2-like receptors, and DA may play different roles than norepinephrine in brain stem vagal circuits.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume292
Issue number4
DOIs
StatePublished - Apr 1 2007

Fingerprint

Dopamine Agents
Motor Neurons
Dopamine
Neurons
Tyrosine 3-Monooxygenase
Mixed Function Oxygenases
varespladib methyl
Brain Stem
Adrenergic Neurons
Stomach
Membranes
3-(4-(4-chlorophenyl-4-hydroxypiperidino)methyl)indole
Solitary Nucleus
Dopamine D2 Receptors
Dopaminergic Neurons
Patch-Clamp Techniques
Norepinephrine

All Science Journal Classification (ASJC) codes

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

Cite this

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title = "Dopamine effects on identified rat vagal motoneurons",
abstract = "Catecholaminergic neurons of the A2 area play a prominent role in brain stem vagal circuits. It is not clear, however, whether these neurons are noradrenergic or adrenergic, i.e., display tyrosine hydroxylase (TH) and dopamine-β-hydroxylase (DβH) immunoreactivity (-IR) or dopaminergic (i.e., TH- but not DβH-IR). Our aims were to investigate whether a subpopulation of neurons in the A2 area was dopaminergic and, if so, to investigate the effects of dopamine (DA) on the membrane of gastric-projecting vagal motoneurons. We observed that although the majority of A2 neurons were both TH- and DβH-IR, a small percentage of nucleus tractus solitarius neurons were TH-IR only, suggesting that DA itself may play role in these circuits. Whole cell recordings from thin brain stem slices showed that 71{\%} of identified gastric-projecting motoneurons responded to DA (1-300 μM) with either an excitation (28{\%}) or an inhibition (43{\%}) of the membrane; the remaining 29{\%} of the neurons were unresponsive. The DA-induced depolarization was mimicked by SK 38393 and prevented by pretreatment with SCH 23390. Conversely, the DA-induced inhibition was mimicked by bromoergocryptine and prevented by pretreatment with L741626. When tested on the same neuron, the effects of DA and NE were not always similar. In fact, in neurons in which DA induced a membrane depolarization, 77{\%} were inhibited by NE, whereas 75{\%} of neurons unresponsive to DA were inhibited by NE. Our data suggest that DA modulates the membrane properties of gastric-projecting motoneurons via D1- and D2-like receptors, and DA may play different roles than norepinephrine in brain stem vagal circuits.",
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Dopamine effects on identified rat vagal motoneurons. / Zheng, Zhongling; Travagli, Renato Alberto.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 292, No. 4, 01.04.2007.

Research output: Contribution to journalArticle

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