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.
Similar content being viewed by others
References
Akaike, A., Shibata, T., Satoh, M. & Takagi, H. Neuropharmacology 17, 775–778 (1978).
Azami, J., Llewelyn, M. D. & Roberts, M. H. T. Pain 12, 229–246 (1982).
Dickenson, A. H., Oliveras, J. L. & Besson, J. M. Brain Res. 170, 95–111 (1979).
Hökfelt, T., Ljungdahl, A., Terenius, L., Elde, R. & Nilsson, G. Proc. natn. Acad. Sci. U.S.A. 74, 3081–3085 (1977).
Basbaum, A. I. & Fields, H. L. Ann. Neurol. 4, 451–462 (1978).
Yaksh, T. L. & Rudy, T. A. Pain 4, 299–359 (1978).
Willis, W. D., Haber, L. H. & Martin, R. F. J. Neurophysiol. 40, 968–981 (1977).
Gebhart, G. F. Pain 12, 93–140 (1982).
Fields, H. L., Hentall, I. D. & Zorman, G. J. Neurosci. Abstr. 8, 806 (1982).
Geller, E. B., Durlofsky, L., Cowan, A., Harakal, C. & Adler, M. W. Life Sci. 25, 139–146 (1979).
Nicoll, R. A., Alger, B. E. & Jahr, C. E. Nature 287, 22–25 (1980).
Frederickson, R. C. A. & Geary, L. E. Prog. Neurobiol. 19, 19–69 (1982).
Vanegas, H., Barbaro, N. M. & Fields, H. L. Soc. Neurosci. Abstr. 9, 3 (1983).
Hentall, I. D., Zorman, G. & Fields, H. L. Soc. Neurosci. Abstr. 7, 734 (1981).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Fields, H., Vanegas, H., Hentall, I. et al. Evidence that disinhibition of brain stem neurones contributes to morphine analgesia. Nature 306, 684–686 (1983). https://doi.org/10.1038/306684a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/306684a0
- Springer Nature Limited
This article is cited by
-
Interactive Mechanisms of Supraspinal Sites of Opioid Analgesic Action: A Festschrift to Dr. Gavril W. Pasternak
Cellular and Molecular Neurobiology (2021)
-
Douleur et thermorégulation. La thermorégulation chez l’animal
Douleur et Analgésie (2015)
-
Contribution of Adenylyl Cyclase Modulation of Pre- and Postsynaptic GABA Neurotransmission to Morphine Antinociception and Tolerance
Neuropsychopharmacology (2014)
-
Diencephalic and brainstem mechanisms in migraine
Nature Reviews Neuroscience (2011)
-
In vitro and in vivo pharmacology of synthetic olivetol‐ or resorcinol‐derived cannabinoid receptor ligands
British Journal of Pharmacology (2006)