title: Protease-activated receptor 2 antagonist potentiates analgesic effects of systemic morphine in a rat model of bone cancer pain.
abstract: OBJECTIVE
  Bone cancer pain affects the quality of life of cancer patients. This study was aimed at investigating the analgesic effects of combined therapies with an antagonist of proteinase-activated receptor (PAR) 2 and morphine on pain-related behaviors in a rat model of bone cancer pain.
  
  
  METHODS
  Female Wistar rats were inoculated intramedullarily with Walker 256 cells into their tibias. The analgesic effects of intraperitoneal treatment with morphine and/or intrathecal with the PAR2 antagonist, FSLLRY-NH2, on bone cancer pain-related behaviors in rats were examined.
  
  
  RESULTS
  Treatment with morphine at 3 or 10 mg/kg significantly improved limb-use and weight-bearing scores and reduced the number of spontaneous flinches in rats. Treatment with FSLLRY-NH2 at 10 mmol/L also significantly improved limb use and weight bearing scores, and reduced the number of spontaneous flinches in rats. Combination a sub-analgesic dose of FSLLRY-NH2 (0.1 mmol/L) and morphine further elevated limb-use and weight-bearing scores and reduced the number of flinches compared with the effects of morphine alone in rats.
  
  
  CONCLUSIONS
  Our data indicate that the combination of morphine and FSLLRY-NH2 has potent analgesic effects on bone cancer pain and our findings may aid in design of new strategies for the treatment of bone cancer pain.
authors: From the Departments of *Oncology and †Nephrology, Guang'anmen Hospital, ‡Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, and §Beijing University of Chinese Medicine, Beijing, China.
authors: Yanju
authors: Y
authors: Bao
authors: Wei
authors: W
authors: Hou
authors: Liping
authors: L
authors: Yang
authors: Xiangying
authors: X
authors: Kong
authors: Maobo
authors: M
authors: Du
authors: Honggang
authors: H
authors: Zheng
authors: Yebo
authors: Y
authors: Gao
authors: Baojin
authors: B
authors: Hua
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001859:Bone Neoplasms / Q000150:complications*; D002279:Carcinoma 256, Walker; D004357:Drug Synergism; D005260:Female; D007274:Injections, Intraperitoneal; D009020:Morphine / Q000494:pharmacology*; D009368:Neoplasm Transplantation; D009842:Oligopeptides / Q000627:therapeutic use*; D010147:Pain Measurement; D010148:Intractable Pain / Q000188:drug therapy*; D051381:Rats; D017208:Rats, Wistar; D044464:Receptor, PAR-2 / Q000037:antagonists & inhibitors*
chemical_list: D000701:Analgesics, Opioid; C508716:H-Phe-Ser-Leu-Leu-Arg-Tyr-NH2; D009842:Oligopeptides; D044464:Receptor, PAR-2; D009020:Morphine