Involvement of platelet-activating factor in ultraviolet B-induced hyperalgesia.
Ultraviolet B (UVB) radiation causes cutaneous inflammation. One important clinical consequence of UVB-induced inflammation is increased pain or hyperalgesia, which is likely mediated by enhanced sensitivity of cutaneous sensory neurons. Previous studies have demonstrated that UVB radiation generates the lipid mediator, platelet-activating factor (PAF), as well as oxidized phospholipids that act as PAF-mimetics. These substances exert effects through the PAF receptor (PAF-R). This study was designed to assess whether PAF-R is involved in UVB-induced hyperalgesia. Intradermal injection of carbamoyl PAF (CPAF; 1-hexadecyl-2-N-methylcarbamoyl glycerophosphocholine) resulted in an enhanced response to mechanical stimuli in wild-type mice but not in PAF-R knockout (KO) mice. There was no significant change in paw withdrawal to noxious thermal stimuli in either genotype after intradermal injection of CPAF. Exposure of the hind paw to 1,500 J m(-2) UVB radiation caused an increased sensitivity to both mechanical and thermal stimulation in wild-type mice but not in PAF-R KO mice. The thermal hyperalgesia caused by UVB irradiation was inhibited in mice that lacked PAF-R in bone marrow-derived cells. These data demonstrate that the PAF-R is important for UVB-induced hyperalgesia. Further investigation of the role of PAF-R signaling in UVB-induced hyperalgesia could provide better understanding of the pathological processes initiated by UVB-induced skin damage.
Zhang
Qiwei
Q
Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
Sitzman
Leslie A
LA
Al-Hassani
Mohammad
M
Cai
Shanbao
S
Pollok
Karen E
KE
Travers
Jeffrey B
JB
Hingtgen
Cynthia M
CM
D000818:Animals; D016026:Bone Marrow Transplantation; D006930:Hyperalgesia / Q000378:metabolism*; D007249:Inflammation; D008055:Lipids / Q000737:chemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008954:Models, Biological; D009474:Neurons / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D010972:Platelet Activating Factor / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D014466:Ultraviolet Rays
D008055:Lipids; D010743:Phospholipids; D010972:Platelet Activating Factor; C083283:1-O-hexadecyl-2-N-methylcarbamol -sn-glycerol-3-phosphocholine; D010100:Oxygen