title: Morphine analgesia suppresses tumor growth and metastasis in a mouse model of cancer pain produced by orthotopic tumor inoculation.
abstract: The present study was conducted to clarify whether relief from cancer pain by morphine would suppress tumor growth and metastasis. When given orthotopic inoculation of B16-BL6 melanoma cells into the hind paw, C57BL/6 mice showed moderate and marked hyperalgesia on days 7-10 and from day 14 post-inoculation, respectively. The volume of inoculated hind paw was increased exponentially as a function of time from day 8 post-inoculation, a phenomena being due to melanoma growth. Lung metastasis was apparent after day 12 post-inoculation. On day 16 post-inoculation, the hyperalgesia was completely inhibited by subcutaneous injection of morphine hydrochloride (5 and 10 mg/kg). The tumor growth and lung metastasis were markedly inhibited by repeated administration of morphine (5 and 10 mg/kg daily for 6 days) and also by the neurectomy of sciatic nerve innervating the inoculated region. The results suggest that relief from cancer pain by morphine inhibits tumor growth and metastasis.
authors.affiliation: Department of Applied Pharmacology, Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Sasamura
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Nakamura
authors.forename: Yuko
authors.initials: Y
authors.lastname: Iida
authors.forename: Hideki
authors.initials: H
authors.lastname: Fujii
authors.forename: Jun
authors.initials: J
authors.lastname: Murata
authors.forename: Ikuo
authors.initials: I
authors.lastname: Saiki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nojima
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kuraishi
mesh_terms: D000701:Analgesics, Opioid / Q000627:therapeutic use*; D000818:Animals; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D008297:Male; D008546:Melanoma, Experimental / Q000150:complications / Q000188:drug therapy*; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000627:therapeutic use*; D009362:Neoplasm Metastasis / Q000188:drug therapy*; D009369:Neoplasms / Q000150:complications / Q000188:drug therapy; D010146:Pain / Q000188:drug therapy* / Q000209:etiology; D023041:Xenograft Model Antitumor Assays / Q000379:methods
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine