Delta阿片受体激动剂DADLE在大鼠缺血性脑损伤中的作用

Effects of delta opioid peptide DADLE on ischemic brain injury in rats

目的研究delta阿片受体激动剂DADLE([D-Ala2,D-Leu5]-enkephalin)在大鼠全脑缺血性脑损伤中的作用。方法 60只成年健康雄性Sprague-Dawley大鼠被随机分入6组,每组10只:假手术对照(Sham)组、人工脑脊液(ACSF)组、DADLE0.2mmol/L(DADLE0.2)组、DADLE2mmol/L(DADLE2)组、DADLE20mmol/L(DADLE20)组和DADLE2mmol/L+纳曲吲哚2mmol/L(联合用药)组。应用立体定位技术分别对各组大鼠的左侧侧脑室注射相应剂量的实验药物10μL。45min后对大鼠行全脑缺血10min,5d后进行运动功能和水迷宫检测,最后处死动物进行脑组织病理学检查。结果 ACSF组的运动功能评分显著低于其他5组(P值均<0.05);3个不同剂量DADLE组间差异均有统计学意义(P值均<0.05),DADLE20组最高,联合用药组显著低于DADLE2和DADLE20组(P值均<0.05)。术后7、8d,ACSF组的水迷宫检测潜伏期均显著长于同时间点的其他5组(P值均<0.05);3个不同剂量DADLE组间同时间点潜伏期的差异均有统计学意义(P值均<0.05),DADLE20组最短,联合用药组均显著长于同时间点的DADLE20组(P值均<0.05)。同时间点各组间及同组各时间点间游泳速度的差异均无统计学意义(P值均>0.05)。术后6、7、8d,ACSF组的目标象限游泳时间均显著短于同时间点的其他5组(P值均<0.05);3个不同剂量DADLE组同时间点目标象限游泳时间的差异均有统计学意义(P值均<0.05),DADLE20组最长,联合用药组均显著短于同时间点的DADLE20组(P值均<0.05)。ACSF组海马CA1区的存活神经元数目显著少于其他5组(P值均<0.05),DADLE剂量依赖性地增加海马CA1区的存活细胞数,3个不同剂量DADLE组同时间点的差异均有统计学意义(P值均<0.05),联合用药组显著少于DADLE2组(P<0.05)。结论 DADLE侧脑室注射具有明显减轻缺血性脑损伤的效应,其作用呈剂量依赖性,其机制主要是激活delta受体,同时亦可能有其他机制参与。

Objective To explore the neuroprotective effects of DADLE （I-D-Ala2,D-Leu5]-enkephalin） on total cerebral ischemia in rats. Methods Sixty adult healthy male Sprague-Dawley rats were randomly divided into six groups （n = 10） ： sham operation group （sham）, artificial cerebral spinal fluid group （ACSF）, DADLE 0.2 mmol/L group （DAD0.2）, DADLE 2 mmol/L group （DAD2）, DADLE 20 mmol/L group （DAD20） and DADLE 2 mmol/L ＋ naltrindole 2 mmol/L group （DAD2-1-N）. With a stereotaxic instrument, the above mentioned solution （10 μL） was injected into the left lateral cerebral ventricle respectively. After 45 minutes, total cerebral ischemia was given for 10 minutes. Five days later, motor function and behaviors changes of the rats were measured. Then the rats were sacrificed and the samples of brain tissue were obtained for pathology. Results The motor functionscore in the ACSF group was significantly less than those in the other groups （all P〈0.05）. There was significant difference in the motor function score among three DADLE groups （all P〈0.05）. The score in the DAD20 group was the highest one and the score in the DAD2 ＋ N group was significantly less than that in the DAD2 group （all P〈0.05）. The latencies on the 7th and 8h days after brain ischemia in the AOSF group were longer than those of other groups （all P〈0.05）. There was significant difference in the latency among three DADLE groups （all P〈 0.05）. The latency was the shortest in the DAD20 group. The latency in the DAD2 ＋ N group was significantly longer than that in the DAD20 group （P〈0.05）. There was no significant difference in swimming speed among groups （all P〈0.05）. In the 6th, 7th and 8 days after brain ischemia, the swimming time spent in the target quadrant in the AOSF group was significantly shorter than those of other groups （all P〈0.05）, and the differences among three DADLE groups were statistically significant （all P〈0.05） DAD20 group had the longest time. The time spent in the target quadrant in the DAD2 ＋ N group was significantly shorter than that in the DAD20 group （ P〈 0.05）. The survival neurons in the CA1 area of hippocampus in the ACSF group was the least compared with other groups （all P〈0.05）. The survival neurons had a dose dependent increase in the three DADLE groups （all P〈 0.05）. The survival neurons in the DAD2 4-N group was significantly less than that in the DAD2 group （P〈0.05）. Conclusion The administration of DADLE in lateral cerebral ventricle have a dose-dependent neuroprotective effect on severe global brain ischemia in rats, which is mainly due to the activation of delta opioid receptor.