1. TRPV1 promotes opioid analgesia during inflammation.
- Author
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Basso L, Aboushousha R, Fan CY, Iftinca M, Melo H, Flynn R, Agosti F, Hollenberg MD, Thompson R, Bourinet E, Trang T, and Altier C
- Subjects
- Acute Pain chemically induced, Acute Pain drug therapy, Acute Pain genetics, Analgesia, Animals, Chronic Pain chemically induced, Chronic Pain drug therapy, Chronic Pain genetics, Disease Models, Animal, Freund's Adjuvant adverse effects, Freund's Adjuvant pharmacology, Humans, Inflammation chemically induced, Inflammation drug therapy, Inflammation genetics, Inflammation metabolism, Mice, Mice, Knockout, Naloxone pharmacology, Quaternary Ammonium Compounds pharmacology, Signal Transduction genetics, TRPV Cation Channels genetics, beta-Arrestin 2 genetics, beta-Arrestin 2 metabolism, Acute Pain metabolism, Analgesics, Opioid pharmacology, Chronic Pain metabolism, Naloxone analogs & derivatives, Narcotic Antagonists pharmacology, Signal Transduction drug effects, TRPV Cation Channels metabolism
- Abstract
Pain and inflammation are inherently linked responses to injury, infection, or chronic diseases. Given that acute inflammation in humans or mice enhances the analgesic properties of opioids, there is much interest in determining the inflammatory transducers that prime opioid receptor signaling in primary afferent nociceptors. Here, we found that activation of the transient receptor potential vanilloid type 1 (TRPV1) channel stimulated a mitogen-activated protein kinase (MAPK) signaling pathway that was accompanied by the shuttling of the scaffold protein β-arrestin2 to the nucleus. The nuclear translocation of β-arrestin2 in turn prevented its recruitment to the μ-opioid receptor (MOR), the subsequent internalization of agonist-bound MOR, and the suppression of MOR activity that occurs upon receptor desensitization. Using the complete Freund's adjuvant (CFA) inflammatory pain model to examine the role of TRPV1 in regulating endogenous opioid analgesia in mice, we found that naloxone methiodide (Nal-M), a peripherally restricted, nonselective, and competitive opioid receptor antagonist, slowed the recovery from CFA-induced hypersensitivity in wild-type, but not TRPV1-deficient, mice. Furthermore, we showed that inflammation prolonged morphine-induced antinociception in a mouse model of opioid receptor desensitization, a process that depended on TRPV1. Together, our data reveal a TRPV1-mediated signaling pathway that serves as an endogenous pain-resolution mechanism by promoting the nuclear translocation of β-arrestin2 to minimize MOR desensitization. This previously uncharacterized mechanism may underlie the peripheral opioid control of inflammatory pain. Dysregulation of the TRPV1-β-arrestin2 axis may thus contribute to the transition from acute to chronic pain., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
- Published
- 2019
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