Effect of microglial inhibitor on spinal proinflammatory cytokines of adjuvant arthritic rats

CHENG Hao; YANG Jian-ping; ZHANG Hui-juan; WANG Li-na

Abstract：Objective:To investigate the expression levels of spinal proinflammatory cytokines in adjuvant ar-thritis rats and the effect of intratheacl minocycline. Methods:After intrathecal catheter was implanted successfully between L_3 and L_4 vertebrae, adult male Sprague-Dawley (SD) rats were pretreated with normal saline or minocycline 50μg for 30 min prior to intradermal injection of 50μL complete freunds adjunvant (CFA) in the right ankle joint, intrathecal normal saline or minocycline was injected once daily for seven consecutive days. Paw withdrawal thermal latency (PWTL) was assessed on 0, 2, 6 and 13 days. The changes of spinal proinflammatory cytokines IL-1β, IL-6 and TNF-α levels were examined by ELISA analysis after 4 hours following intrathecal normal saline or minocycline at 0, 2, 6 d and 13 days after CFA injection. Results:Minocycline administered intratheaclly inhibited shortening of PWTL. The expression levels of IL-1β, IL-6 and TNF-α in the spine cord were obviously increased after CFA injec-tion. It markedly inhibited the increase of spinal IL-1β, IL-6 and TNF-α levels at corresponding time point. Conclu-sion:Intratheacl minocycline could inhibit the increase of CFA-induced spinal proinflammatory cytokines. Spinal mi-croglia perhaps mediates the inflammatory hyperalgesia by proinflammatory cytokines.