Evidence that disinhibition of brain stem neurones contributes to morphine analgesia

H. L. Fields, H. Vanegas, Ian Hentall, G. Zorman

Research output: Contribution to journalArticle

194 Citations (Scopus)

Abstract

Analgesia results when opiates are microinjected into the rostral ventromedial medulla (RVM)1-3. This region, which includes the nucleus raphe magnus and the adjacent reticular formation, is rich in immunoreactive enkephalin-containing neurones and terminals4, and contains neurones that project to the spinal cord dorsal horn where they inhibit identified nociceptive spinothalamic tract neurones5-7. Although opiates have previously been reported either to excite or inhibit RVM cells8, the possibility of an opiate effect being consistent within a physiologically defined subclass has not been examined. Recently we described a class of neurone in the RVM (the off-cell) that abruptly pauses just before a heat-evoked tail-flick reflex9. If off-cells are made to fire continuously by direct electrical stimulation of the RVM, the tail-flick reflex does not occur. We report here that analgesic doses of morphine completely eliminate the pause in firing that precedes the tail-flick reflex. We propose that this disinhibition of off-cells in the RVM is a primary process contributing to opiate inhibition of nociceptor-induced reflexes.

Original languageEnglish
Pages (from-to)684-686
Number of pages3
JournalNature
Volume306
Issue number5944
StatePublished - Dec 1 1983
Externally publishedYes

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Opiate Alkaloids
Analgesia
Morphine
Brain Stem
Reflex
Neurons
Spinothalamic Tracts
Nociceptors
Reticular Formation
Enkephalins
Electric Stimulation
Analgesics
Hot Temperature

ASJC Scopus subject areas

  • General

Cite this

Fields, H. L., Vanegas, H., Hentall, I., & Zorman, G. (1983). Evidence that disinhibition of brain stem neurones contributes to morphine analgesia. Nature, 306(5944), 684-686.

Evidence that disinhibition of brain stem neurones contributes to morphine analgesia. / Fields, H. L.; Vanegas, H.; Hentall, Ian; Zorman, G.

In: Nature, Vol. 306, No. 5944, 01.12.1983, p. 684-686.

Research output: Contribution to journalArticle

Fields, HL, Vanegas, H, Hentall, I & Zorman, G 1983, 'Evidence that disinhibition of brain stem neurones contributes to morphine analgesia', Nature, vol. 306, no. 5944, pp. 684-686.
Fields HL, Vanegas H, Hentall I, Zorman G. Evidence that disinhibition of brain stem neurones contributes to morphine analgesia. Nature. 1983 Dec 1;306(5944):684-686.
Fields, H. L. ; Vanegas, H. ; Hentall, Ian ; Zorman, G. / Evidence that disinhibition of brain stem neurones contributes to morphine analgesia. In: Nature. 1983 ; Vol. 306, No. 5944. pp. 684-686.
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