title: Characterisation of ultraviolet-B-induced inflammation as a model of hyperalgesia in the rat.
abstract: In humans, the acute inflammatory reaction caused by ultraviolet (UV) radiation is well studied and the sensory changes that are found have been used as a model of cutaneous hyperalgesia. Similar paradigms are now emerging as rodent models of inflammatory pain. Using a narrowband UVB source, we irradiated the plantar surface of rat hind paws. This produced the classical feature of inflammation, erythema, and a significant dose-dependent reduction in both thermal and mechanical paw withdrawal thresholds. These sensory changes peaked 48h after irradiation. At this time there is a graded facilitation of noxious heat evoked (but not basal) c-fos-like immunoreactivity in the L4/5 segments of the spinal cord. We also studied the effects of established analgesic compounds on the UVB-induced hyperalgesia. Systemic as well as topical application of ibuprofen significantly reduced both thermal and mechanical hyperalgesia. Systemic morphine produced a dose-dependent and naloxone sensitive reversal of sensory changes. Similarly, the peripherally restricted opioid loperamide also had a dose-dependent anti-hyperalgesic effect, again reversed by naloxone methiodide. Sequestration of NGF, starting at the time of UVB irradiation, significantly reduced sensory changes. We conclude that UVB inflammation produces a dose-dependent hyperalgesic state sensitive to established analgesics. This suggests that UVB inflammation in the rat may represent a useful translational tool in the study of pain and the testing of analgesic agents.
authors.affiliation: Neurorestoration Group, The Wolfson Centre for Age Related Diseases, King's College London, The Wolfson Wing, Hodgkin Building, Guy's Campus, London Bridge, London SE1 1UL, United Kingdom.
authors.forename: T
authors.initials: T
authors.lastname: Bishop
authors.forename: D W
authors.initials: DW
authors.lastname: Hewson
authors.forename: P K
authors.initials: PK
authors.lastname: Yip
authors.forename: M S
authors.initials: MS
authors.lastname: Fahey
authors.forename: D
authors.initials: D
authors.lastname: Dawbarn
authors.forename: A R
authors.initials: AR
authors.lastname: Young
authors.forename: S B
authors.initials: SB
authors.lastname: McMahon
mesh_terms: D000818:Animals; D016207:Cytokines / Q000276:immunology; D004195:Disease Models, Animal; D006930:Hyperalgesia / Q000209:etiology* / Q000276:immunology*; D008297:Male; D011855:Radiodermatitis / Q000209:etiology* / Q000276:immunology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014466:Ultraviolet Rays
chemical_list: D016207:Cytokines