Effects of intrathecal injection rapamycin on neuropathic pain behaviors in mice / 中华行为医学与脑科学杂志

ABSTRACT

Objective To investigate the effects of continuously intrathecal injection rapamycin on neuro pathic pain behaviors in mice.Methods 48 male adult C57/BL6 mice received intrathecal catheter implantation successfully and without motor dysfunction and serious weight loss,were choosed and randomly divided into shamoperation group ( sham,n =24) and chronic constriction injury model group ( CCI,n =24 ).After operation,each group randomly divided into 3 group again.Group I did nothing,group Ⅱ intrathecally injected rapamycin 1 μg/5μlon day 1 to 6 after operation,group Ⅲ intrathecally injected 20％ DMSO 5μl on the same time ( sham,CCI,sham +R,sham + V,CCI + R,CCI + V,n =8 ).Bilateral mechanical paw withdrawal threshold (WMT) and thermal paw withdrawal latency(TWL) were tested on day 1 before CCI and day 1,3,5,7,10,14,17,21,28 after operation.Results Compared with sham group,both WMT and TWL (7d,MWT:( 1.02 ±0.12)g vs (0.42 ±0.12)g,F=51.01,P＜0.05;TWL:(7.03 ±0.71 )s vs (3.26 ±0.66)s,F=38.27,P＜0.05) were significantly decreased after CCI on the ipsilateral side.When intrathecally injected Rapamycin 1 μg/5 μl on day 1 ～6 after CCI,the mechanical allodynia relieved obviously ( 7 d,M WT:( 0.42 ± 0.18 ) g vs ( 0.86 ± 0.25 ) g,F =6.56,P ＜ 0.05 ),and at least continued to 10 d.On the contrary,the effects of rapamycin on thermal hyperalgesia just showed a trend of inhibition,there was no statistic meaning.In addition,the sham group and contralateral pain behaviors did not change (P＞ 0.05 ).Conclusion Rapamycin can relieve the neuropathic pain behaviors in mice after CCI,mainly the mechanical allodynia,but not thermal hyperalgesia.