Role of spinal bombesin-responsive neurons in nonhistaminergic itch

Tasuku Akiyama, Mitsutoshi Tominaga, Kenji Takamori, Mirela Iodi Carstens, Earl Carstens

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Intrathecal administration of the neurotoxin bombesin-saporin reduces or abolishes pruritogenevoked scratching behavior. We investigated whether spinal neurons that respond to intradermal (ID) injection of pruritogens also respond to spinal superfusion of bombesin and vice versa. Single-unit recordings were made from superficial lumbar spinal dorsal horn neurons in anesthetized mice. We identified neurons with three search strategies: 1) ID injection of the nonhistaminergic itch mediator chloroquine, 2) spinal superfusion of bombesin, and 3) noxious pinch. All units were tested with an array of itch mediators (chloroquine, histamine, SLIGRL, BAM8-22), algogens [capsaicin, allyl isothiocyanate (AITC)], and physical stimuli (brush, pinch, noxious heat, cooling) applied to the hindlimb receptive field. The vast majority of chloroquine-responsive units also responded to bombesin. Of 26 chloroquine-sensitive units tested, most responded to SLIGRL, half responded to histamine and/or BAM8-22, and most responded to capsaicin and/or AITC as well as noxious thermal and mechanical stimuli. Of 29 bombesinresponsive units, a large majority also responded to other itch mediators as well as AITC, capsaicin, and noxious thermal and mechanical stimuli. Responses to successive applications of bombesin exhibited tachyphylaxis. In contrast, of 36 units responsive to noxious pinch, the majority (67%) did not respond to ID chloroquine or spinal bombesin. It is suggested that chloroquine-and bombesin-sensitive spinal neurons signal itch from the skin.

Original languageEnglish (US)
Pages (from-to)2283-2289
Number of pages7
JournalJournal of Neurophysiology
Volume112
Issue number9
DOIs
StatePublished - Nov 1 2014

Keywords

  • Bombesin
  • Gastrin-releasing peptide
  • Mice
  • Mrgpr
  • Superficial dorsal horn
  • TRPA1
  • TRPV1

ASJC Scopus subject areas

  • Physiology
  • Neuroscience(all)

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  • Cite this

    Akiyama, T., Tominaga, M., Takamori, K., Carstens, M. I., & Carstens, E. (2014). Role of spinal bombesin-responsive neurons in nonhistaminergic itch. Journal of Neurophysiology, 112(9), 2283-2289. https://doi.org/10.1152/jn.00409.2014