Inflammation enhances Y1 receptor signaling, neuropeptide Y-mediated inhibition of hyperalgesia, and substance P release from primary afferent neurons

B. K. Taylor, W. Fu, K. E. Kuphal, C. O. Stiller, M. K. Winter, W. Chen, G. F. Corder, J. H. Urban, K. E. McCarson, J. C. Marvizon

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Neuropeptide Y (NPY) is present in the superficial laminae of the dorsal horn and inhibits spinal nociceptive processing, but the mechanisms underlying its anti-hyperalgesic actions are unclear. We hypothesized that NPY acts at neuropeptide Y1 receptors in the dorsal horn to decrease nociception by inhibiting substance P (SP) release, and that these effects are enhanced by inflammation. To evaluate SP release, we used microdialysis and neurokinin 1 receptor (NK1R) internalization in rat. NPY decreased capsaicin-evoked SP-like immunoreactivity in the microdialysate of the dorsal horn. NPY also decreased non-noxious stimulus (paw brush)-evoked NK1R internalization (as well as mechanical hyperalgesia and mechanical and cold allodynia) after intraplantar injection of carrageenan. Similarly, in rat spinal cord slices with dorsal root attached, [Leu31, Pro34]-NPY inhibited dorsal root stimulus-evoked NK1R internalization. In rat dorsal root ganglion neurons, Y1 receptors colocalized extensively with calcitonin gene-related peptide (CGRP). In dorsal horn neurons, Y1 receptors were extensively expressed and this may have masked the detection of terminal co-localization with CGRP or SP. To determine whether the pain inhibitory actions of Y1 receptors are enhanced by inflammation, we administered [Leu31, Pro34]-NPY after intraplantar injection of complete Freund's adjuvant (CFA) in rat. We found that [Leu31, Pro34]-NPY reduced paw clamp-induced NK1R internalization in CFA rats but not uninjured controls. To determine the contribution of increased Y1 receptor-G protein coupling, we measured [35S]GTPγS binding simulated by [Leu31, Pro34]-NPY in mouse dorsal horn. CFA inflammation increased the affinity of Y1 receptor G-protein coupling. We conclude that Y1 receptors contribute to the anti-hyperalgesic effects of NPY by mediating the inhibition of SP release, and that Y1 receptor signaling in the dorsal horn is enhanced during inflammatory nociception.

Original languageEnglish (US)
Pages (from-to)178-194
Number of pages17
JournalNeuroscience
Volume256
DOIs
StatePublished - Jan 3 2014

Bibliographical note

Funding Information:
Supported by NIH R01NS45954 to B.K.T. and J.C.M. and K02DA19656 to B.K.T. and NICHD HD02528 to K.E.M.

Keywords

  • Calcitonin gene-related peptide
  • Capsaicin
  • G-protein
  • Isolectin B4
  • Neurokinin-1 receptor
  • Pain

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