BAM8-22 peptide produces itch and nociceptive sensations in humans independent of histamine release

J Neurosci. 2011 May 18;31(20):7563-7. doi: 10.1523/JNEUROSCI.1192-11.2011.

Abstract

Chronic itch accompanying many dermatological, neurological, and systemic diseases is unresponsive to antihistamines. Our knowledge of endogenous chemicals that evoke histamine-independent itch and their molecular targets is very limited. Recently it was demonstrated in behavioral and cellular experiments that bovine adrenal medulla 8-22 peptide (BAM8-22), a proteolytically cleaved product of proenkephalin A, is a potent activator of Mas-related G-protein-coupled receptors (Mrgprs), MrgprC11 and hMrgprX1, and induces scratching in mice in an Mrgpr-dependent manner. To study the sensory qualities that BAM8-22 evokes in humans, we tested the volar forearm of 15 healthy volunteers with heat-inactivated cowhage spicules previously soaked in the peptide. BAM8-22 produced itch in each subject, usually accompanied by sensations of pricking/stinging and burning. The sensations were occasionally accompanied by one or more mechanically evoked dysesthesias, namely alloknesis, hyperknesis, and/or hyperalgesia, but no wheal or neurogenic flare in the skin surrounding the application site. The inactive truncated peptide BAM8-18 produced weak or no sensations. Pretreatment of the tested skin with an antihistamine cream (doxepin) inhibited histamine-induced sensations, dysesthesias, and skin reactions but not the sensations and dysesthesias evoked by BAM8-22. We show that BAM8-22 produces itch and nociceptive sensations in humans in a histamine-independent manner. Thus, BAM8-22 may be an endogenous itch mediator that activates, in humans, MrgprX1, a novel target for potential anti-itch treatments.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Animals
  • Cattle
  • Enkephalins / toxicity*
  • Female
  • Histamine Release / drug effects
  • Histamine Release / physiology*
  • Humans
  • Male
  • Middle Aged
  • Pain / chemically induced*
  • Pain / physiopathology
  • Peptide Fragments / toxicity*
  • Protein Precursors / toxicity*
  • Pruritus / chemically induced*
  • Pruritus / physiopathology
  • Sensation / drug effects
  • Sensation / physiology*
  • Young Adult

Substances

  • Enkephalins
  • Peptide Fragments
  • Protein Precursors
  • proenkephalin