Tags

Type your tag names separated by a space and hit enter

Nociceptive facilitating neurons in the rostral ventromedial medulla.
Pain. 2004 Jul; 110(1-2):158-65.PAIN

Abstract

The role of the periaqueductal gray-rostral ventromedial medulla (RVM) system in descending inhibition of nociception has been studied for over 30 years. The neural basis for this antinociceptive action is reasonably well understood, with strong evidence that activation of a class of RVM neurons termed 'off-cells' exerts a net inhibitory effect on nociception. However, it has recently become clear that this system can facilitate, as well as inhibit pain. Although the mechanisms underlying the facilitation of nociception have not been conclusively identified, indirect evidence points to activation of a class of neurons termed 'on-cells' as mediating descending facilitation. Here we used focal infusion of the tridecapeptide neurotensin within the RVM in lightly anesthetized rats to activate on-cells selectively. Neurotensin has been shown in awake animals to produce a dose-related, bi-directional effect on nociception when applied within the RVM, with hyperalgesia at low doses, and analgesia at higher doses. Using a combination of single cell recording and behavioral testing, we now show that on-cells are activated selectively by low-dose neurotensin, and that the activation of on-cells by neurotensin results in enhanced nociceptive responding, as measured by the paw withdrawal reflex. Furthermore, higher neurotensin doses recruit off-cells in addition to on-cells, producing behavioral antinociception. Selective activation of on-cells is thus sufficient to produce hyperalgesia, confirming the role of these neurons in facilitating nociception. Activation of on-cells likely contributes to enhanced sensitivity to noxious stimulation or reduced sensitivity to analgesic drugs in a variety of conditions.

Authors+Show Affiliations

Department of Neurological Surgery, L-472, Oregon Health and Science University, Portland, OR 97239, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15275763

Citation

Neubert, Miranda J., et al. "Nociceptive Facilitating Neurons in the Rostral Ventromedial Medulla." Pain, vol. 110, no. 1-2, 2004, pp. 158-65.
Neubert MJ, Kincaid W, Heinricher MM. Nociceptive facilitating neurons in the rostral ventromedial medulla. Pain. 2004;110(1-2):158-65.
Neubert, M. J., Kincaid, W., & Heinricher, M. M. (2004). Nociceptive facilitating neurons in the rostral ventromedial medulla. Pain, 110(1-2), 158-65.
Neubert MJ, Kincaid W, Heinricher MM. Nociceptive Facilitating Neurons in the Rostral Ventromedial Medulla. Pain. 2004;110(1-2):158-65. PubMed PMID: 15275763.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Nociceptive facilitating neurons in the rostral ventromedial medulla. AU - Neubert,Miranda J, AU - Kincaid,Wendy, AU - Heinricher,Mary M, PY - 2003/12/04/received PY - 2004/02/04/revised PY - 2004/03/09/accepted PY - 2004/7/28/pubmed PY - 2004/10/27/medline PY - 2004/7/28/entrez SP - 158 EP - 65 JF - Pain JO - Pain VL - 110 IS - 1-2 N2 - The role of the periaqueductal gray-rostral ventromedial medulla (RVM) system in descending inhibition of nociception has been studied for over 30 years. The neural basis for this antinociceptive action is reasonably well understood, with strong evidence that activation of a class of RVM neurons termed 'off-cells' exerts a net inhibitory effect on nociception. However, it has recently become clear that this system can facilitate, as well as inhibit pain. Although the mechanisms underlying the facilitation of nociception have not been conclusively identified, indirect evidence points to activation of a class of neurons termed 'on-cells' as mediating descending facilitation. Here we used focal infusion of the tridecapeptide neurotensin within the RVM in lightly anesthetized rats to activate on-cells selectively. Neurotensin has been shown in awake animals to produce a dose-related, bi-directional effect on nociception when applied within the RVM, with hyperalgesia at low doses, and analgesia at higher doses. Using a combination of single cell recording and behavioral testing, we now show that on-cells are activated selectively by low-dose neurotensin, and that the activation of on-cells by neurotensin results in enhanced nociceptive responding, as measured by the paw withdrawal reflex. Furthermore, higher neurotensin doses recruit off-cells in addition to on-cells, producing behavioral antinociception. Selective activation of on-cells is thus sufficient to produce hyperalgesia, confirming the role of these neurons in facilitating nociception. Activation of on-cells likely contributes to enhanced sensitivity to noxious stimulation or reduced sensitivity to analgesic drugs in a variety of conditions. SN - 0304-3959 UR - https://www.unboundmedicine.com/medline/citation/15275763/Nociceptive_facilitating_neurons_in_the_rostral_ventromedial_medulla_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0304395904001502 DB - PRIME DP - Unbound Medicine ER -