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A subset of μ-opioid receptor-expressing cells in the rostral ventromedial medulla contribute to thermal hyperalgesia in experimental neuropathic pain.
Neurosci Res. 2011 May; 70(1):35-43.NR

Abstract

The rostral ventromedial medulla (RVM) is a major region for the descending modulation of pain at the spinal cord level, and neurons in the RVM have been implicated in the inhibition and facilitation of spinal nociceptive transmission. Although recent studies have established that the RVM facilitation of nociceptive transmission in the spinal cord contributes to neuropathic pain, the underlying mechanisms remain largely unknown. In the present study, we investigated the effects of kainic acid (KA)-induced RVM damage on neuropathic pain behavior and the expression of molecules implicated in pain modulation. KA was injected into the RVM midline region after neuropathic pain was established by chronic constrictive injury of the left sciatic nerve. Thermal hyperalgesia, but not mechanical allodynia, was persistently suppressed in the ipsilateral paw by a single KA injection into the RVM for at least the next 7 days in a rat neuropathic pain model. KA injection alone did not affect the nocifensive responses to mechanical and thermal stimuli on the intact side. Immunohistochemical analysis revealed that KA injection into the RVM significantly reduced the number of immunoreactive neurons for μ-opioid receptors, but not tryptophan hydroxylase, in association with the analgesic effect. These results suggest that a subset of RVM neurons expressing μ-opioid receptors contribute to the maintenance of thermal hyperalgesia in neuropathic pain.

Authors+Show Affiliations

Department of Anesthesiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21238509

Citation

Mase, Hiroshi, et al. "A Subset of Μ-opioid Receptor-expressing Cells in the Rostral Ventromedial Medulla Contribute to Thermal Hyperalgesia in Experimental Neuropathic Pain." Neuroscience Research, vol. 70, no. 1, 2011, pp. 35-43.
Mase H, Sakai A, Sakamoto A, et al. A subset of μ-opioid receptor-expressing cells in the rostral ventromedial medulla contribute to thermal hyperalgesia in experimental neuropathic pain. Neurosci Res. 2011;70(1):35-43.
Mase, H., Sakai, A., Sakamoto, A., & Suzuki, H. (2011). A subset of μ-opioid receptor-expressing cells in the rostral ventromedial medulla contribute to thermal hyperalgesia in experimental neuropathic pain. Neuroscience Research, 70(1), 35-43. https://doi.org/10.1016/j.neures.2011.01.003
Mase H, et al. A Subset of Μ-opioid Receptor-expressing Cells in the Rostral Ventromedial Medulla Contribute to Thermal Hyperalgesia in Experimental Neuropathic Pain. Neurosci Res. 2011;70(1):35-43. PubMed PMID: 21238509.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A subset of μ-opioid receptor-expressing cells in the rostral ventromedial medulla contribute to thermal hyperalgesia in experimental neuropathic pain. AU - Mase,Hiroshi, AU - Sakai,Atsushi, AU - Sakamoto,Atsuhiro, AU - Suzuki,Hidenori, Y1 - 2011/01/14/ PY - 2010/10/22/received PY - 2010/12/29/revised PY - 2011/01/05/accepted PY - 2011/1/18/entrez PY - 2011/1/18/pubmed PY - 2012/4/7/medline SP - 35 EP - 43 JF - Neuroscience research JO - Neurosci Res VL - 70 IS - 1 N2 - The rostral ventromedial medulla (RVM) is a major region for the descending modulation of pain at the spinal cord level, and neurons in the RVM have been implicated in the inhibition and facilitation of spinal nociceptive transmission. Although recent studies have established that the RVM facilitation of nociceptive transmission in the spinal cord contributes to neuropathic pain, the underlying mechanisms remain largely unknown. In the present study, we investigated the effects of kainic acid (KA)-induced RVM damage on neuropathic pain behavior and the expression of molecules implicated in pain modulation. KA was injected into the RVM midline region after neuropathic pain was established by chronic constrictive injury of the left sciatic nerve. Thermal hyperalgesia, but not mechanical allodynia, was persistently suppressed in the ipsilateral paw by a single KA injection into the RVM for at least the next 7 days in a rat neuropathic pain model. KA injection alone did not affect the nocifensive responses to mechanical and thermal stimuli on the intact side. Immunohistochemical analysis revealed that KA injection into the RVM significantly reduced the number of immunoreactive neurons for μ-opioid receptors, but not tryptophan hydroxylase, in association with the analgesic effect. These results suggest that a subset of RVM neurons expressing μ-opioid receptors contribute to the maintenance of thermal hyperalgesia in neuropathic pain. SN - 1872-8111 UR - https://www.unboundmedicine.com/medline/citation/21238509/A_subset_of_μ_opioid_receptor_expressing_cells_in_the_rostral_ventromedial_medulla_contribute_to_thermal_hyperalgesia_in_experimental_neuropathic_pain_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0168-0102(11)00007-1 DB - PRIME DP - Unbound Medicine ER -