Irradiation of skin using Ultraviolet B (UVB) light has been characterized as a model of inflammatory pain in both human and rat subjects, making it a useful translational pharmacodynamic pain model to characterize analgesic effects of novel therapeutics (Bishop et al. 2007 & 2009).
Thermal Sensitivity Following UVB Irradiation
In rats, UVB irradiation of the plantar surface of the hind paw results in erythema and pain behaviors measured as hypersensitivity to a noxious heat stimulus using the Hargreaves test. The pain response is maximal on Days 2 and 3 following irradiation and persists through Day 7. NSAIDs such as naproxen alleviate the UVB-induced pain response.
Figure 1: A: time course for development of left hind paw heat hypersensitivity following UVB irradiation of the left hind paw (1000 mJ/cm2) in male Sprague Dawley rats. Heat hypersensitivity was measured using the Hargreaves test as the paw withdrawal latency (PWL). B: Oral administration of naproxen (3 – 30 mg/kg) dose-dependently reduced hind paw heat hypersensitivity on day 3 post irradiation.
References
- Bishop T, Hewson D W, Yip P K, Fahey M S, Dawbarn D, Young A R and McMahon S B (2007). Characterization of ultraviolet-B-induced inflammation as a model of hyperalgesia in the rat. Pain 131:70-82
- Bishop T, Ballard A, Holmes H, Young A R and McMahon S B (2009) Ultraviolet-B induced inflammation of human skin: characterization and comparison with traditional models of hyperalgesia. Eur J Pain 13:524-532