Blockade of Opioid Receptors in the Medullary Reticularis Nucleus Dorsalis, but not the Rostral Ventromedial Medulla, Prevents Analgesia Produced by Diffuse Noxious Inhibitory Control in Rats With Muscle Inflammation

JOURNAL OF PAIN

卷:12

Article

de Resende, Marcos A.²  Arendt-Nielsen, Lars³  Sluka, Kathleen A.¹ 

[1] Univ Iowa, Grad Program Phys Therapy & Rehabil Sci, Coll Med, Iowa City, IA 52242 USA

[2] Univ Fed Minas Gerais, Rehabil Sci Program, Belo Horizonte, MG, Brazil

[3] Aalborg Univ, Ctr Sensory Motor Interact SMI, Dept Hlth Sci & Technol, Aalborg, Denmark

关键词: Pain;    muscle;    inhibition;    DNIC;    opioid;   

DOI  :  10.1016/j.jpain.2010.12.009

来源: Elsevier

【 摘 要 】

Diffuse Noxious Inhibitory Controls (DNIC) involves application of a noxious stimulus outside the testing site to produce analgesia. In human subjects with a variety of chronic pain conditions, DNIC is less effective; however, in animal studies, DNIC is more effective after tissue injury. While opioids are involved in DNIC analgesia, the pathways involved in this opioid-induced analgesia are not clear. The aim of the present study was to test the effectiveness of DNIC in inflammatory muscle pain, and to study which brainstem sites mediate DNIC- analgesia. Rats were injected with 3% carrageenan into their gastrocnemius muscle and responses to cutaneous and muscle stimuli were assessed before and after inflammation, and before and after DNIC induced by noxious heat applied to the tail (45 C and 47 C). Naloxone was administered systemically, into rostral ventromedial medulla (RVM), or bilaterally into the medullary reticularis nucleus dorsalis (MdD) prior to the DNIC-conditioning stimuli. DNIC produced a similar analgesic effect in both acute and the chronic phases of inflammation reducing both cutaneous and muscle sensitivity in a dose-dependent manner. Naloxone systemically or microinjected into the MdD prevented DNIC-analgesia, while naloxone into the RVM had no effect on DNIC analgesia. Thus, DNIC analgesia involves activation of opioid receptors in the MdD. Perspective: The current study shows that DNIC activates opioid receptors in the MdD, but not the RVM, to produce analgesia. These data are important for understanding clinical studies on DNIC as well as for potential treatment of chronic pain patients. (C) 2011 by the American Pain Society

【 授权许可】

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