Back to Search Start Over

Excitation of Mouse Superficial Dorsal Horn Neurons by Histamine and/or PAR-2 Agonist: Potential Role in Itch.

Authors :
Tasuku Akiyama
Carstens, Mirela Iodi
Carstens, E.
Source :
Journal of Neurophysiology. Oct2009, Vol. 102 Issue 4, p2176-2183. 8p.
Publication Year :
2009

Abstract

Recent studies have suggested the existence of separate transduction mechanisms and sensory pathways for histamine and nonhistaminergic types of itch. We studied whether histamine and an agonist of the protease-activated receptor (PAR)-2, associated with nonhistaminergic itch, excite murine dorsal horn neurons. Single units were recorded in superficial lumbar dorsal horn of adult ICR mice anesthetized with pentobarbital. Unit activity was searched using a small intradermal hindpaw injection of histamine or the PAR-2 agonist SLIGRL-NH2. Isolated units were subsequently challenged with intradermal histamine followed by SLIGRL-NH2 (each 50 µg/l µl) or reverse order, followed by mechanical, thermal, and algogenic stimuli. Forty-three units were classified as wide dynamic range (62%), nociceptive specific (22%), or mechano insensitive (16%). Twenty units gave prolonged (mean, 10 min) discharges to intradermal injection of histamine; 76% responded to subsequent SLIGRL-NH2, often more briefly. Units additionally responded to noxious heat (63%), cooling (43%), topical mustard oil (53%), and intradermal capsaicin (67%). Twenty-two other units gave prolonged (mean, 5 min) responses to initial intradermal injection of SLIGRL-NH2; 85% responded to subsequent intradermal histamine. They also responded to noxious heat (75%), mustard oil (93%), capsaicin (63%), and one to cooling. Most superficial dorsal horn neurons were excited by both histamine and the PAR-2 agonist, suggesting overlapping pathways for histamine- and non--histamine-mediated itch. Because the large majority of pruritogen-responsive neurons also responded to noxious stimuli, itch may be signaled at least partly by a population code. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00223077
Volume :
102
Issue :
4
Database :
Academic Search Index
Journal :
Journal of Neurophysiology
Publication Type :
Academic Journal
Accession number :
97747055
Full Text :
https://doi.org/10.1152/jn.00463.2009