鞘内注射米诺环素减轻大鼠佐剂性关节炎性痛觉过敏

Intrathecal minocycline attenuates thermal hyperalgesia in a rat model of CFA-induced arthritis

目的研究鞘内注射(it)米诺环素(minocycline,M)对大鼠完全氟氏佐剂(complete Freunds adjunvant,CFA)性关节炎性痛觉过敏的作用。方法蛛网膜下腔置管成功的♂SD大鼠,在右踝关节外侧皮下注射50μlCFA前30min分别it生理盐水(NS)或12.5、25、50μg的米诺环素,it每天1次,持续7d,观察热刺激回缩潜伏期(paw withdrawal thermal latency,PWTL)14d。CFA致炎后2d、6d,it米诺环素50μg,观察24h的PWTL变化;右踝关节外侧皮下注射50μlNS前30minit米诺环素50μg、NS20μl,观察24h的PWTL变化。结果米诺环素it不改变无炎症大鼠的PWTL;CFA致炎后PWTL缩短,米诺环素抑制致炎后PWTL的减少似呈剂量依赖性;预先及CFA致炎后2d米诺环素it可抑制PWTL的减少,d6则无明显影响。结论米诺环素it可减轻炎性痛觉过敏;对已存在的痛觉过敏,早期it作用较强,后期it则无明显作用。

Aim To observe effects of intrathecal （it） minocycline on thermal hyperalgesia in a rat model of CFA-induced arthritis. Methods After intrathecal catheter being implanted successfully, adult male Sprague-dawley （SD） rats were pretreated with normal saline or 12. 5, 25, 50μg different dose minocycline intrathecally 30 min prior to subcutaneously injection of 50μl complete Freunds adjunvant （CFA） in the fight tibio-tarsal joint. Intrathecal normal saline or minocycline was injected daily for 7 days. Paw withdrawal thermal latency （PWTL） was assessed for 14 days. Minocycline 50 μg was been given intrathecally on day 2 and day 6 after CFA injection. Intrathecal minocydine 50μg or normal saline was injected 30 min prior to subcutaneously injection of 50 μl normal saline in the fight tibio-tarsal joint. PWTL was assessed for 24 h. Results Intrathecal minocycline to noinflamed rats did not alter PWTL; PWTL was shortened after CFA- induced arthritis, pretreatment with intrathecal minocycline inhibited the shortening of PWTL to seem in a does-dependent way in inflamed rats. Intrathecal minocycline 50μg inhibited reducing of PWTL on day 2, but failed to alter on day 6 after CFA-induced inflammatory pain. Conclusions Intrathecal minocycline attenuates thermal hyperalgesia induced by CFA; it inhibited powerfully existed hyperalgesia in early phase, but had no effect in late phase.