Intrathecal Injection of JWH-015 Attenuates Bone Cancer Pain Via Time-Dependent Modification of Pro-inflammatory Cytokines Expression and Astrocytes Activity in Spinal Cord

Inflammation. 2015 Oct;38(5):1880-90. doi: 10.1007/s10753-015-0168-3.

Abstract

Cannabinoid receptor type 2 (CB2) agonists display potential analgesic effects in acute and neuropathic pain. However, its complex cellular and molecular mechanisms in bone cancer pain remain unclear. And less relevant reports concerned its time-dependent effects on the long-lasting modifications of behavior, spinal inflammatory cytokines levels, astrocytes activity induced by bone cancer pain. A rat model of bone cancer pain induced by intra-tibia inoculation of Walker 256 mammary gland carcinoma cells was utilized. Pain behaviors at different time points were assessed by ambulatory pain scores and paw withdrawal mechanical threshold (PWMT). Pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, IL-18, and tumor necrosis factor alpha (TNF-α), were quantitated by Western blots. Glial activity was assessed by immunohistochemistry. Intra-tibia inoculation of Walker 256 mammary gland carcinoma cells induced progressive bone cancer pain; a long-term up-regulation of IL-1β, IL-6, IL-18, and TNF-α; and the activation of glia in spinal cord. Activation of microglia was first evident on day 4 after surgery and reached to a peak on day 7 while activation of astrocytes was on day 10. A single intrathecal injection of JWH-015 attenuated bone cancer induced spontaneous pain and mechanical allodynia, reduced the expression of pro-inflammatory cytokines, and inhibited the activity of astrocytes. All the modifications were transient and peaked at 24 h after JWH-015 administration. Furthermore, the protective effects of JWH-015 were reversed in the presence of CB2-selective antagonist AM630. Overall, our results provided evidences for the persistent participation of inflammation reaction in the progression of bone cancer pain, and demonstrated that JWH-015 reduced the expression of IL-1β, IL-6, IL-18, and TNF-α and inhibited astrocytes activation in a time-dependent manner, thereby displaying an analgesic effect.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / drug effects
  • Astrocytes / metabolism*
  • Bone Neoplasms / complications
  • Bone Neoplasms / drug therapy
  • Bone Neoplasms / metabolism*
  • Cytokines / antagonists & inhibitors
  • Cytokines / biosynthesis*
  • Female
  • Indoles / administration & dosage*
  • Inflammation Mediators / antagonists & inhibitors
  • Inflammation Mediators / metabolism*
  • Injections, Spinal
  • Pain / drug therapy
  • Pain / etiology
  • Pain / metabolism*
  • Pain Measurement / drug effects
  • Pain Measurement / methods
  • Rats
  • Rats, Sprague-Dawley
  • Spinal Cord / drug effects
  • Spinal Cord / metabolism*
  • Time Factors

Substances

  • Cytokines
  • Indoles
  • Inflammation Mediators
  • JHW 015