Background and Objectives: Minocycline is a second-generation tetracycline with multiple biological effects, including inhibition of microglial activation. Recently, microglial activation has been implicated in the development of nerve injury-induced neuropathic pain. In this study, the authors examined the effects of continuous intrathecal minocycline on the development of neuropathic pain and microglial activation induced by L5/6 spinal-nerve ligation in rats. Methods: Under isoflurane anesthesia, male Sprague-Dawley rats (200-250 g) received right L5/6 spinal-nerve ligation and intrathecal catheters connected to an infusion pump. Intrathecal saline or minocycline (2 and 6 μg/h) was given continuously after surgery for 7 days (n = 8 per group). The rat right hind paw withdrawal threshold to von Frey filament stimuli and withdrawal latency to radiant heat were determined before surgery and on days 1 to 7 after surgery. Spinal microglial activation was evaluated with OX-42 immunoreactivity on day 7 after surgery. Results: Spinal-nerve ligation induced mechanical allodynia and thermal hyperalgesia on the affected hind paw of saline-treated rats. Intrathecal minocycline (2 and 6 μg/h) prevented the development of mechanical allodynia and thermal hyperalgesia induced by nerve ligation. It also inhibited nerve ligation-induced microglial activation, as evidenced by decreased OX-42 staining. No obvious histopathologic change was noted after intrathecal minocycline (6 μg/h) infusion. Conclusions: In this study, the authors demonstrate the preventive effect of continuous intrathecal minocycline on the development of nociceptive behaviors induced by L5/6 spinal-nerve ligation in rats. Further studies are required to examine if continuous intrathecal minocycline could be used safely in the clinical setting.
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine
Lin, C. S., Tsaur, M. L., Chen, C. C., Wang, T. Y., Lin, C. F., Lai, Y. L., Hsu, T. C., Pan, Y. Y., Yang, C. H., & Cheng, J. K. (2007). Chronic Intrathecal Infusion of Minocycline Prevents the Development of Spinal-Nerve Ligation-Induced Pain in Rats. Regional Anesthesia and Pain Medicine, 32(3), 209-216. https://doi.org/10.1016/j.rapm.2007.01.005