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Mediators of Inflammation
Volume 2016 (2016), Article ID 5093095, 8 pages
http://dx.doi.org/10.1155/2016/5093095
Research Article

Radiotherapy Suppresses Bone Cancer Pain through Inhibiting Activation of cAMP Signaling in Rat Dorsal Root Ganglion and Spinal Cord

1Center for Clinical Research and Translational Medicine, Lianyungang Oriental Hospital, Lianyungang, Jiangsu 222042, China
2Department of Anesthesiology, Lianyungang Oriental Hospital, Lianyungang, Jiangsu 222042, China
3Division of Anesthesiology & Pain Medicine, Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education of China, Beijing Cancer Hospital, Peking University, Beijing 100142, China
4Department of Anesthesiology, Beijing Cancer Hospital, Peking University, Beijing 100142, China

Received 24 July 2015; Revised 10 January 2016; Accepted 18 January 2016

Academic Editor: Dianne Cooper

Copyright © 2016 Guiqin Zhu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Radiotherapy is one of the major clinical approaches for treatment of bone cancer pain. Activation of cAMP-PKA signaling pathway plays important roles in bone cancer pain. Here, we examined the effects of radiotherapy on bone cancer pain and accompanying abnormal activation of cAMP-PKA signaling. Female Sprague-Dawley rats were used and received tumor cell implantation (TCI) in rat tibia (TCI cancer pain model). Some of the rats that previously received TCI treatment were treated with X-ray radiation (radiotherapy). Thermal hyperalgesia and mechanical allodynia were measured and used for evaluating level of pain caused by TCI treatment. PKA mRNA expression in dorsal root ganglion (DRG) was detected by RT-PCR. Concentrations of cAMP, IL-1β, and TNF-α as well as PKA activity in DRG and the spinal cord were measured by ELISA. The results showed that radiotherapy significantly suppressed TCI-induced thermal hyperalgesia and mechanical allodynia. The level of PKA mRNA in DRG, cAMP concentration and PKA activity in DRG and in the spinal cord, and concentrations of IL-1β and TNF-α in the spinal cord were significantly reduced by radiotherapy. In addition, radiotherapy also reduced TCI-induced bone loss. These findings suggest that radiotherapy may suppress bone cancer pain through inhibition of activation of cAMP-PKA signaling pathway in DRG and the spinal cord.