Descending facilitation from rostral ventromedial medulla mu opioid receptor-expressing neurons is necessary for maintenance of sensory and affective dimensions of chronic neuropathic pain.

Autor:	Dogrul BN; Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States., Machado Kopruszinski C; Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States., Dolatyari Eslami M; Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States., Watanabe M; Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States., Luo S; Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States., Moreira de Souza LH; Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States., Vizin RL; Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States., Yue X; Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States., Palmiter RD; Department of Biochemistry, University of Washington, Seattle, WA, United States., Navratilova E; Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States., Porreca F; Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States.
Jazyk:	angličtina
Zdroj:	Pain [Pain] 2025 Jan 01; Vol. 166 (1), pp. 153-159. Date of Electronic Publication: 2024 Jul 26.
DOI:	10.1097/j.pain.0000000000003360
Abstrakt:	Abstract: Pharmacological ablation of rostral ventromedial medulla (RVM) mu opioid receptor-expressing cells before peripheral nerve injury prevents the development of neuropathic pain. However, whether these neurons are required for the expression of established neuropathic pain is not known. Male Oprm1Cre heterozygous (MOR Cre ) or wild-type (MOR WT ) mice received AAV8-hSyn-DIO-hM4D(Gi)-mCherry in the RVM. After partial sciatic nerve ligation (PSNL), we evaluated pain behaviors and descending control of nociception in response to acute or sustained chemogenetic inhibition of RVM-MOR cells expressing hM4D(Gi). A single systemic administration of hM4D(Gi) agonist clozapine-N-oxide (CNO) reversibly inhibited hind paw tactile allodynia and produced conditioned place preference only in MOR Cre mice with PSNL. Intrathecal CNO also reversibly inhibited PSNL-induced hind paw allodynia, suggesting that the spinal projections from these RVM-MOR cells are critical for manifestation of pain behaviors. Consistent with enhanced descending facilitation from RVM-MOR cells, MOR Cre -hM4D(Gi) mice with PSNL showed diminished descending control of nociception that was restored by systemic CNO. Sustained CNO in drinking water before PSNL prevented expression of chronic pain without affecting acute surgical pain; however, relief of chronic pain required sustained CNO treatment. Thus, in male mice, activity of spinally projecting RVM-MOR cells is required (1) for expression and manifestation of both sensory and affective dimensions of established neuropathic pain and (2) to promote descending facilitation that overcomes apparently intact descending inhibition to maintain chronic pain. Enhanced descending facilitation likely regulates the output signal from the spinal cord to the brain to shape the pain experience and may provide a mechanism for nonopioid management of pain. (Copyright © 2024 International Association for the Study of Pain.)
Databáze:	MEDLINE
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