title: Mechano-insensitive nociceptors are sufficient to induce histamine-induced itch.
abstract: The nerve fibres underlying histamine-induced itch have not been fully elucidated. We blocked the lateral femoral cutaneous nerve and mapped the skin area unresponsive to mechanical stimulation, but still sensitive to electrically induced pain. Nerve block induced significantly larger anaesthetic areas to mechanical (100 mN pin-prick, 402 ± 61 cm²; brush, 393 ± 63 cm²) and heat pain stimuli (401 ± 53 cm²) compared with electrical stimulation (352 ± 62 cm², p < 0.05), whereas the anaesthetic area tested with 260 mN (374 ± 57 cm²) did not differ significantly. Histamine was applied by iontophoresis (7.5 mC) at skin sites in which mechanical sensitivity was blocked, but electrical stimulation was still perceived 30 min after the nerve block (n = 9). In these areas iontophoresis of histamine provoked itching in 8/9 subjects with a mean maximum of 4.6 ± 1 (on an 11-point rating scale). Histamine-induced itch can thus be perceived at skin sites where input from mechano-sensitive polymodal nociceptors is blocked. In conclusion, input from mechano-insensitive nociceptors is sufficient to generate histamine-induced itch.
authors: Department of Anesthesiology, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.
authors: Marcus
authors: M
authors: Schley
authors: Roman
authors: R
authors: Rukwied
authors: James
authors: J
authors: Blunk
authors: Christian
authors: C
authors: Menzer
authors: Christoph
authors: C
authors: Konrad
authors: Martin
authors: M
authors: Dusch
authors: Martin
authors: M
authors: Schmelz
authors: Justus
authors: J
authors: Benrath
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D005267:Femoral Nerve; D006632:Histamine / Q000008:administration & dosage / Q000633:toxicity*; D006358:Hot Temperature; D006801:Humans; D007478:Iontophoresis; D008297:Male; D040542:Mechanotransduction, Cellular; D009407:Nerve Block / Q000379:methods; D009619:Nociceptors / Q000378:metabolism*; D010147:Pain Measurement; D058748:Pain Perception; D017288:Pain Threshold; D011537:Pruritus / Q000139:chemically induced* / Q000378:metabolism / Q000503:physiopathology; D012867:Skin / Q000294:innervation*; D013997:Time Factors; D055815:Young Adult
chemical_list: D006632:Histamine