芒针对促进大鼠急性脊髓损伤功能修复的机制研究

摘要

目的 观察芒针对急性脊髓损伤炎症反应和神经细胞凋亡的影响,研究PI3K/Akt和MAPK/ERK信号转导途径是否参与芒针的神经保护作用,探讨芒针促脊髓损伤修复的具体作用机制.方法 将150只成年雄性SD大鼠随机分为A组、B组、C组、D组和E组,每组30只.采用改良Allen's法制作大鼠脊髓中度损伤模型,A组为假手术组,不予以损伤脊髓及芒针治疗;B组造模后不予以芒针治疗;C组造模后采用芒针治疗;D组造模前0.5 h鞘内注射LY294002,造模后采用芒针治疗;E组造模前0.5 h鞘内注射PD98059,造模后采用芒针治疗.分别采用BBB评分检测大鼠的自发活动;ELISA检测炎性因子TNF-α 、IL-6、IL-1β、NF-κB的含量;TUNEL检测细胞凋亡的程度;免疫组化检测Bcl-2和Bax阳性细胞水平;Western印迹分析p-Akt和p-ERK在脊髓组织的表达,RT-PCR分析Cyt-C和Caspase-3在体内的表达.相对的下行Akt和ERK信号通路通过LY294002和PD98059特异性抑制剂处理分析在体内的抑制作用.结果 炎症反应和PI3K/Akt和MAPK/ERK信号通路抑制的神经元凋亡参与了脊髓损伤大鼠模型的损害,芒针介导的神经保护作用与Bax蛋白阳性神经元数目的减少及Bcl-2蛋白阳性神经元数量的增加有关.芒针治疗能改善大鼠的运动功能,PI3K/Akt和MAPK/ERK信号通路中p-Akt和p-ERK的激活,通过下调Bax蛋白和Bcl-2表达上调,抑制了线粒体凋亡途径关键因子Cyt-C的表达.TUNEL法检测并抑制激活神经元凋亡的Caspase-3的级联.PI3K/Akt和MAPK/ERK信号通路特异性抑制剂LY294002和PD98059的应用抑制了p-Akt和p-ERK的表达.结论 芒针促脊髓损伤修复的神经保护作用可能与炎症反应和PI3K/Akt和MAPK/ERK信号通路的激活、通过下调Bax蛋白和Bcl-2表达上调以及抑制线粒体途径诱导的凋亡有关.%Objective To observe the effect of elongated needle acupuncture on inflammatory reactions and apoptosis in acute spinal cord injury, investigate if PI3K/Akt and MAPK/ERK signal transduction pathways are involved in the neuroprotective effect of elongated needle acupuncture and explore the promoting action of elongated needle acupuncture on spinal cord injury repair.Method One hundred and fifty adult male SD rats were randomized into groups A, B, C, D and E, 30 each. A model of moderate spinal cord injury was made by modified Allen's method. Group A received a sham operation without spinal cord injury and no elongated needle acupuncture. Group B did not receive elongated needle acupuncture after model making. Group C received elongated needle acupuncture after model making. Group D received an intrathecal injection of LY294002 at 0.5 hour before model making and elongated needle acupuncture after model making. Group E received an intrathecal injection of PD98059 at 0.5 hour before model making and elongated needle acupuncture after model making. Rat spontaneous activity was examined using the BBB rating. Inflammatory cytokines TNF-α, IL-6, IL-1β and NF-κB contents were measured by ELISA. The degree of apoptosis was determined by TUNEL. Bcl-2- and Bax-positive cell levels were measured by an immunohistochemical method. Spinal p-Akt and p-ERK expressions were determined by Western blot. In vivo expressions of Cyt-C and Caspase-3 were determined by RT-PCR. The in vivo inhibitory effect on downstream Akt and ERK signaling pathways was investigated using specific inhibitors LY294002 and PD98059.Result Inflammatory reactions and neuronal apoptosis due to the inhibition of PI3K/Akt and MAPK/ERK signal pathways were involved in the damage in a rat model of spinal cord injury. The neuroprotective effect of elongated needle acupuncture was related to a decrease in the number of Bax protein-positive neurons and an increase in the number of Bcl-2 protein-positive neurons. Elongated needle acupuncture treatment improved rat motor function, activated p-Akt and p-ERK in PI3K/Akt and MAPK/ERK signal pathways by down-regulating Bax protein expression and up-regulating Bcl-2 protein expression and inhibited the expression of Cyt-C, a key factor in the mitochondrial apoptosis pathway. TUNEL detected and inhibited the activation of caspase-3 cascade in neuronal apoptosis. Application of specific inhibitors LY294002 and PD98059 to PI3K/Akt and MAPK/ERK signaling pathways inhibited the expression p-Akt and p-ERK expressions.Conclusion JIN's three needle therapy plus mirror therapy for knee joint movement is an effective approach in treating hemiplegia after cerebral infarction, and it can improve the lower-limb motor function and the ADL.