Suppression of interleukin-6 by minocycline in a rat model of neuropathic pain.

Inflammatory mediators produced in the injured nerve have been proposed as contributing factors in the development of neuropathic pain. In this regard an important role is assigned to interleukin-6. The present study, evaluated the effect of pretreatment with minocycline, on pain behavior (hyperalgesia and allodynia) and serum level of interleukin-6 in chronic constriction injury (CCI) model of neuropathic pain in rat. Minocycline (5, 10, 20 and 40 mg/kg, i.p.) was injected 1 h before surgery and continued daily to day 14 post-ligation. Behavioral tests were recorded before surgery and on postoperative days 1, 3, 5, 7, 9, 10, 14, and the serum concentration of interleukin-6 was determined at day 14. We observed that minocycline which was reported to have a neuroprotective effect in some neurodegenerative diseases, reversed hyperalgesia and allodynia due to sciatic nerve ligation and inhibited the interleukin-6 production. It seems that minocycline could have an anti-inflammatory and analgesic effect in some chronic pain states.