脊髓蛋白酶体在大鼠慢性吗啡耐受形成中的作用

目的 评价脊髓蛋白酶体在大鼠慢性吗啡耐受形成中的作用.方法 取鞘内置管成功的健康雄性大鼠24只,采用随机数字表法,将大鼠随机分为4组(n=6),生理盐水组(NS组)、慢性吗啡耐受组(M组)、吗啡+蛋白酶体抑制剂MG-132组(M+ MG组)和MG-132组(MG组)于每天8:00和20:00分别鞘内注射生理盐水10 μl、吗啡10μg、吗啡10 μg+ MG-132 2.5μg、MG,-132 2.5 μg,连续7d.于鞘内注射前1 d(基础值)、鞘内注射第1、3、5和7天时测定大鼠甩尾潜伏期,以计算最大抗伤害效应百分比(MPAE).于最后一次鞘内注射结束后取5只大鼠,处死后取L3-5脊髓,采用Western blot法测定谷氨酸-天冬氨酸转运体(GLAST)和兴奋性氨基酸转运体1(EAAC1)的表达水平.结果 M组和M+MG组鞘内注射期间MPAE逐渐降低(P＜0.05)；与NS组比较,M组和M+ MG组鞘内注射期间MPAE升高,M组脊髓GLAST和EAAC1表达下调(P＜0.05),M+ MG组脊髓GLAST和EAAC1表达差异无统计学意义,MG组上述指标差异均无统计学意义(P＞0.05)；与M组比较,M+ MG组MPAE升高,脊髓GLAST和EAACI表达上调(P＜0.05或0.01).结论 脊髓蛋白酶体参与了大鼠慢性吗啡耐受的形成.

Role of spinal cord proteasome in chronic morphine tolerance in rats

Objective To evaluate the role of the spinal cord proteasome in chronic morphine tolerance in rats.Methods Twenty-four healthy male SD rats in which intrathecal catheters were successfully placed without complications were randomized into 4 groups ( n =6 each):normal saline group ( group NS),chronic morphine tolerance group (group M),chronic morphine tolerance + proteasome inhibitor MG-132 group (group M + MG) and MG-132 group (group MG).Normal saline 10 μl,morphine 10 μg,morphine 10 μg+ MG-132 2.5 μg and MG-132 2.5 μg were injected intrathecally twice a day for 7 consecutive days in groups NS,M,M + MG and MG respectively.Tail flick latency was measured on day 1 before intrathecal injection and on day 1,3,5 and 7 of intrathecal injection to calculate the percentage of maximum possible antinociceptive effect (MPAE).After the last intrathecal injection,5 rats were sacrificed,and L3-5 spinal cord was removed for determination of the expression of glutamate-aspartate transporter (GLAST) and excitatory amino acids carrier 1 (EAAC1)by Western blot.Results MPAE was gradually decreased during the intrathecal injection in groups M and M + MG( P ＜ 0.05).Compared with group NS,MPAE was gradually incresed during the intrathecal injection in groups M and M + MG,and the expression of GLAST and EAAC1 in the spinal cord was significantly down-regulated in group M (P ＜ 0.05).There was no significant difference in the parameters mentioned above between group MG and group NS ( P ＞0.05 ).Compared with group M,MPAE was significantly increased and the expression of GLAST and EAAC1 in the spinal cord was significantlyup-regulatedingroupM+MG(P＜0.05or0.01).Conclusion Spinal cord proteasome is involved in the development of chronic morphine tolerance in rats.