Effects of intraathecal methotrexate on mechanical allodynia in rats with tibial bone cancer pain / 中华麻醉学杂志

ABSTRACT

Objective To investigate effects of intrathecal methotrexate on mechanical allodynia in rats with tibial bone cancer pain.Methods Forty-eight female SD rats weighing 150-180 g were randomly divided into 6 groups ( n =8 each)group Ⅰ sham operation + artificial cerebrospinal fluid(SA group),group Ⅱ sham operation + methotrexate 200 μg(SM group),group Ⅲ bone cancer pain + artificial cerebrospinal fluid(CA group),group Ⅳ-Ⅵ bone cancer pain + different doses of methotrexate (CM1-3 groups).The model of tibial bone cancer pain was induced by injecting Walker-256 cell into the tibial marrow cavity.CA and CM1-3 groups were intrathecal injected artificial cerebrospinal fluid,methotrexate 50,100 and 200 μg.SA and SM200 groups were intrathecal injected artificial cerebrospinal fluid and methotrexate 200 μg.The mechanical withdrawl threshold (MWT) was measured at day 1 before Walker-256 injection (baseline),7 day after injection (T0 ) and 2,4,8,24 hour and 1,3,5,7 days after intrathecal injection ( T1-8 ).Results Compered with the baseline,MWT was decrease in CA and CM1-s groups.Competed with To,MWT was decreased at T5-8 in CA group,MWT was increased at T3-5 in CM1 group,at T2-6 in CM2 group and at T2-7 in CM3 groups.MWT was decrease in CA and CM1-3 groups as compered with SA group; MWT was increased at T4-7 in CM1 group and at T3-7 in CM2 and CM3 groups.Conclusion Intrathecal injection of methotrexate can reduce tibial bone cancer pain in rats.