Intrathecal clonidine decreases spinal nitric oxide release in a rat model of Complete Freund's Adjuvant induced inflammatory pain

C. R. Lin, Y. C. Chuang, J. T. Cheng, C. J. Wang, L. C. Yang

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

A long-lasting antihyperalgesic effect has been demonstrated for intrathecal (IT) clonidine, an alpha2-adrenergic agonist. In the present study, the mechanism and antihyperalgesic effects of IT clonidine were examined post-treatment in a rat model of Complete Freund's Adjuvant (CFA)-induced inflammatory hyperalgesia. Using a chronic model of spinal cord dialysis, we examined the effect of the adjuvant-induced inflammation on spinal release of nitric oxide (NO) and the development of chronic pain and assessed the antinociceptive effects and mechanisms of the alpha2-adrenergic agonist, clonidine (IT). Chronic, persistent inflammatory pain was induced by left hind paw injection of 0.3 ml CFA prepared in a mixture with Mycobacterium butyricum. Rats were randomly assigned to groups receiving IT clonidine in discrete doses of 1, 10 or 50 μg, 3 or 24 hr post-inflammation. Measurement of total NOx (NO + NO2-+ NO3-) was used to determine NO release into the cerebrospinal fluid. Rat thermal antinociception was assessed using a radiant heat thermal hyperalgesia model. CFA injection resulted in significant thermal hyperalgesia throughout the four days of observation. A dose-dependent suppression of thermal hyperalgesia and spinal NO release was observed after IT clonidine treatment. Evidence from this CFA-induced inflammatory pain model suggests that clonidine's spinal antihyperalgesic mechanisms act through inhibition of spinal NO release.

Original languageEnglish
Pages (from-to)161-166
Number of pages6
JournalInflammation
Volume26
Issue number4
DOIs
Publication statusPublished - 2002

All Science Journal Classification (ASJC) codes

  • Immunology and Allergy
  • Immunology

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