Role of p38MAPK signal transduction pathway in dexmedetomidine against neurotoxicity induced by bupivacaine / 临床麻醉学杂志

ABSTRACT

Objective To evaluate the role of p38 MAPK signal transduction pathway in dexmedetomidine against neurotoxicity induced by bupivacaine.Methods Seventy-two adult male SD rats,successfully implanted with intrathecal catheter without complications,were randomly divided into 6 groups control group (group C);p38MAPK inhibitor group(group SB);dexmedetomidine group (group D);bupivacaine group (group B);dexmedetomidine and bupivacaine group (group DB);p38MAPK inhibitor and bupivacaine group (group SBB).DMSO 20 μl were injected intrathecally in group C;p38MAPK inhibitor 30 μg and 5% bupivacaine were respectively injected intrathecally in group SB and B;group DB and SBB were respectivel pretreated with dexmedetomidine 75 μg/kg intraperitoneally and p38MAPK inhibitor 30 μg intrathecal injection 20 min before intrathecally injected 5% bupivacaine.Dexmedetomidine 75 μg/kg was injected intraperitoneally in group D.Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured before intrathecal catheter was implanted (T0),before intrathecal administration (T1) and at 4,8 and 12 h and on 1,2,3,4,5 and 6 days after intrathecal administration (T2-T10).At 24 h after intrathecal administration,6 rats were randomly chosen from each group and sacrificed.The lumbar segment (L4-5) of the spinal cord was removed for detecting neuronal apoptosis (by TUNEL) and phosporylated p38MAPK(p-p38MAPK) expression (by Western blot).Results Compared with T0,MWT was significantly increased and TWL was prolonged at T2-T9 in group B,MWT at T2-T7 was significantly increased and TWL at T2-T6 was prolonged in group DB,MWT was significantly increased and TWL was prolonged at T2-T5 in group SBB (P<0.05).Compared with group C,no significant difference was found in MWT,TWL,the apoptotic index and expression of p-p38MAPK in groups D and SB.MWT was significantly increased and TWL was prolonged at T2-T9 in group B,the apoptotic index and expression of p-p38MAPK were significantly increased in group B (P<0.05).Compared with group B,MWT and TWL at T2-T9,the apoptotic index and expression of p-p38MAPK were significantly decreased in groups DB and SBB (P<0.05).Conclusion Dexmedetomidine can inhibit spinal neurotoxicity induced by bupivacaine in rats via inhibiting apoptosis in spinal cord,and inhibition of p38 MAPK signal transduction pathway may be involved in the underlying mechanism.