Further characterization of nociception-related and arterial pressure-related neuronal responses in the nucleus reticularis gigantocellularis of the rat

Terry B.J. Kito, Cheryl C.H. Yang, Julie Y.H. Chan, Hsing Fei Tsai, Samuel H.H. Chan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The present study was undertaken to further characterize the nucleus reticularis gigantocellularis (NRGC) of the medulla oblongata in the central processing of nociceptive and cardiovascular signals, and its modulation by metenkephalin. In Sprague-Dawley rats anesthetized with pentobarbital sodium, we found that all 125 spontaneously active NRGC neurons that responded to noxious stimuli (tail clamp) also exhibited arterial pressure-relatedness. Forty neurons additionally manifested cardiac periodicity that persisted even during nociceptive responses. While maintaining their cardiovascular responsive characteristics, the nociception-related NRGC neuronal activity was blocked, naloxone-reversibly (0.5 mg/kg, i.v.), by morphine (5 mg/kg, i.v.). Microiontophoretically applied met-enkephalin suppressed the responsiveness of NRGC neurons to individually delivered tail clamp or transient hypertension induced by phenylephrine (5 μg/kg, i.v.). Interestingly, in NRGC neurons that manifested both nociception and arterial pressure relatedness, the preferential reduction in the response to noxious stimuli upon simultaneous elevation in systemic arterial pressure was reversed to one that favored nociception in the presence of met-enkephalin. All actions of met-enkephalin were discernibly blocked by the opioid receptor antagonist, naloxone. Our results suggest that individual NRGC neurons may participate in the processing of both nociceptive and cardiovascular information, or in the coordination of the necessary circulatory supports during nociception. In addition, neuropeptides such as met-enkephalin may exert differential modulation on neuronal responsiveness according to the prevailing physiologic status of the animal. They also showed that NRGC may be a central integrator for pain and cardiovascular related functions.

Original languageEnglish
Pages (from-to)338-347
Number of pages10
JournalJournal of Biomedical Science
Volume3
Issue number5
DOIs
StatePublished - 1996

Keywords

  • Arterial pressure-related response
  • Caridac rhythm-related response
  • Met-enkephaline
  • Morphine
  • Naloxone
  • Nociception-related response
  • Nucleus reticularis gigantocellularis
  • Somato-autonomic integration

Fingerprint

Dive into the research topics of 'Further characterization of nociception-related and arterial pressure-related neuronal responses in the nucleus reticularis gigantocellularis of the rat'. Together they form a unique fingerprint.

Cite this