基于PI3K/PTEN/AKT信号途径探讨褪黑素对脊髓损伤大鼠突触可塑性的影响

目的:探讨褪黑素对脊髓损伤大鼠突触可塑性的影响及磷脂酰肌醇3-激酶/张力蛋白同源基因/蛋白激酶B(PI3K/PTEN/AKT)信号途径在其中的作用。方法:选择4月龄SPF级雄性SD大鼠48只,将其随机分为对照组(CON)、模型组(SCI)、褪黑素组(MT)和褪黑素受体拮抗剂组(LUZ),每组12只大鼠。对照组大鼠背部切口后缝合,余下各组大鼠使用改良的Allen's法建立T9水平的脊髓损伤模型。模型建立后,褪黑素组及褪黑素受体拮抗剂组每天腹腔注射褪黑素及褪黑素抑制剂,剂量为12.5 mg·kg~(-1)·d~(-1),对照组和模型组每天注射同体积的生理盐水。治疗后第3、7、14、21、28天进行BBB评分,实验结束处死大鼠取胸椎8-10节段脊髓组织,分别采用免疫组化方法测尼氏小体数量及Western Blot检测PTEN、Synapsin、PSD-95、Gap-43、Akt蛋白的表达。结果:与SCI模型大鼠相比,MT给药干预14 d后的SCI大鼠BBB评分及痛觉压力值均明显降低(P0.05),尼氏小体灰度值提高(P 0.05),PTEN、Synapsin、PSD-95、Gap-43、Akt蛋白的表达均显著上调(P 0.05)。结论:MT可能通过激活PI3K/PTEN/Akt信号途径,上调突触可塑性相关蛋白的表达,促进SCI大鼠突触修复。

Effect of Melatonin on Synaptic Plasticity in Rats with Spinal Cord Injury Based on PI3K/PTEN/AKT Signaling Pathway

ABSTRACT Objective: To investigate the effects of melatonin on synaptic plasticity in rats with spinal cord injury and the role of PI3K/PTEN/AKT signaling pathway. Methods: Forty-eight SPF male Sprague-Dawley rats aged 4 months were randomly divided into control group (CON), model group (SCI), melatonin group (MT) and the melaclonin receptor antagonist group (Luz), 12 in each group. Rats in the control group were sutured after the incision, and the remaining groups of rats were used to establish a T9 level spinal cord injury model using the modified Allen''s method. After the model was established, the rats in MT and LUZ were intraperitoneally injected with melatonin and melatonin inhibitor at a dose of 12.5 mg·kg^-1·d^-1. Rats in CON and the SCI were injected with the same volume of physiological saline daily. BBB scores were performed on the 3rd, 7th, 14th, 21st, and 28th day after treatment. At the end of the experiment, the rats were sacrificed and the spinal cord tissue of 8-10 segments was taken. The number of Nissl bodies and expressio of Synapsin, PSD-95, Gap-43, Akt protein. were detected by immunohistochemistry and Western Blot. Results: After 14 days of MT administration, the BBB score of SCI rats could be significantly reduced, the pain pressure value could be reduced, the gray value of Nissl bodies increased, and the expression of PTEN, Synapsin, PSD-95, Gap-43 and Akt protein could be up-regulated. Conclusion: MT may up-regulate the expression of synaptic plasticity-related proteins by activating the PI3K/PTEN/Akt signaling pathway and promote synaptic repair in SCI rats.