罗哌卡因致大鼠脊髓神经毒性时Bax和Bcl-2表达的变化

目的 评价罗哌卡因致大鼠脊髓神经毒性时Bax和Bcl-2表达的变化,以探讨罗哌卡因脊髓神经毒性的机制.方法 清洁级雄性SD大鼠,体重260～300 g,按改良Yaksh法鞘内置入脊髓微导管,取鞘内置管成功的大鼠54只,随机分为3组(n=18):生理盐水组(NS组)、0.5%罗哌卡因组(R1组)和1%罗哌卡因组(R2组).R1组和R2组于置管后第7天经脊髓微导管分别注射0.5%、1%罗哌卡因0.12μl/g,注药速率10 μl/15 s,每隔1.5小时给药1次,给药期24 h,共注药16次,NS组注射等容量生理盐水.于最后1次鞘内注射罗哌卡因或生理盐水后,每隔10分钟行双下肢运动阻滞评分1次,共5次(T1-5),以评价运动阻滞效果;于鞘内注射罗哌卡因或生理盐水后6、12和24 h(T6-8)时随机取6只大鼠,处死后取脊髓,光镜和电镜下观察病理学结构,并测定脊髓组织Bax和Bcl-2的表达水平.结果 与NS组比较,R1组T1,2时、R2组,T1-3时大鼠双下肢运动阻滞评分升高,R1组脊髓组织Bax、Bcl-2表达均上调(P<0.05),Bcl-2/Bax比值差异无统计学意义(P>0.05),R2组脊髓组织Bax表达上调(P<0.05),Bcl-2表达差异无统计学意义(P>0.05),Bcl-2/Bax比值降低(P<0.05).R1组超微结构改变主要为线粒体和内质网轻度肿胀,而神经细胞未发生凋亡;R2组脊髓神经细胞出现了核固缩等早期凋亡改变.结论 罗哌卡因的脊髓神经毒性可能与激活神经细胞线粒体凋亡途径有关.

Changes in expression of Bax and Bcl-2 in spinal cord in rats during neurotoxicity induced by rapivacaine

Objective To investigate the effect of intrathecal ropivacaine on the expression of Bax and Bcl-2 in rat spinal cord. Methods Fifty-four male SD rats, weighing 260-300 g, successfully implanted with microspinal catheter following the method of Yaksh, were randomly assigned to one of 3 groups (n=18 each):group normal saline (NS), group 0.5% ropivacaine (R1) and group 1% ropivacaine (R2). In group R1 and R2,0.5% and 1% ropivacaine 0.12 μl/g was administered through microspinal catheter at a rate of 10 μl/15 s every 1.5 h (T1-5) for 24 h respectively. The equal volume of normal saline was administered in group NS. After the last administration of ropivacaine or normal saline, the degree of motor block of both lower limbs was assessed every 10 min for 5 times (T1-5). At 6, 12 and 24 h after the hat administration of ropivacaine or normal saline (T6-8),six rats were chosen randomly from each group and killed. The lumbar spinal cord tissue was removed for microscopic examination and determination of Bax and Bcl-2 expression by the method of immunohistochemistry.Results The degree of motor block was significantly higher at T1,2 in group R1 and at T1-3 in group R2 than in group NS (P<0.05).The expression of Bax and Bcl-2 was significantly higher in group R1 than in group NS (P<0.05), but there was no difference in Bcl-2/Bax ratio between the 2 greups(P>0.05). The expression of Bax was significantly higher and Bcl-2/Bax ratio lower in group R2 than in group NS (P<0.05), but there was no difference in the expression of Bcl-2 between the 2 groups (P>0.05). The mild edema of the mitochondria and endoplasmic reticulum was the major histopathologic change in group R1, without apoptosis, but the early change of apoptosis were observed in group R2. Conclusion The spinal neurotoxicity induced by intrathecal injection of ropivacainc may be related to the activation of the mitochondrial apoptosis pathway.