吡咯烷二硫代氨基甲酸铵对创伤性脑损伤大鼠神经炎症的作用及机制

Effect and mechanism of ammonium pyrrolidine dithiocarbamate on neuroinflammation in rats with traumatic brain injury

目的探讨吡咯烷二硫代基甲酸铵(PDTC)对创伤性脑损伤(TBI)大鼠半暗带神经炎症损伤的作用及机制。方法将60只Sprague Dawley大鼠按随机数字表法分为PDTC组、TBI组、假手术组、对照组,每组15只。PDTC组大鼠于术前15 min腹腔注射PDTC(100 mg·kg-1),TBI组、假手术组及对照组大鼠腹腔注射等体积双蒸水。TBI组和PDTC组大鼠开颅窗后,将内径6.0 mm的2.5 g钢棒从内径7.0 mm聚氯乙烯透明管高度自75 cm自由下落,撞击硬脑膜致右顶叶脑挫裂伤,制备TBI模型;假手术组大鼠开颅窗后用骨蜡封闭,不施加打击;对照组大鼠正常饲养。造模后1、4、7 d,应用改良的神经损伤评分(mNSS)评估各组大鼠神经行为学损害程度;造模后2 d,取4组大鼠各5只,断头处死,取脑组织,行苏木精-伊红(HE)染色,光学显微镜下观察脑组织形态学改变;应用免疫组织化学染色检测各组大鼠脑组织中β-淀粉样前体蛋白(β-APP)及胶质纤维酸性蛋白(GFAP)表达。造模后24 h,4组大鼠各取5只,断头取右侧损伤半暗带组织,应用Western blot检测各组大鼠右侧损伤半暗带组织中核转录因子-κB(NF-κB)P65、磷酸化NF-κB P65、NF-κB抑制蛋白(IκB)、磷酸化IκB、核苷酸结合寡聚化结构域样受体蛋白3(NLRP3)及caspase-1蛋白的表达,实时定量聚合酶链式反应检测各组大鼠右侧损伤半暗带组织中NF-κB P65、IκB、NLRP3及caspase-1 mRNA的表达。结果造模后1、4、7 d,TBI组大鼠mNSS评分均显著高于PDTC、对照组、假手术组,PDTC组大鼠mNSS评分显著高于对照组和假手术组(P<0.05);假手术组与对照组大鼠mNSS评分比较差异无统计学意义(P>0.05)。对照组及假手术组大鼠的神经元及神经胶质细胞形态正常,无肿胀,细胞间质无增宽。TBI组大鼠脑组织出现弥漫性出血性改变,神经元胞体形态不一,细胞膜与细胞质分辨不清,细胞核固缩,常为三角形,正常结构及核仁皆消失,弥漫性白细胞、红细胞填充视野。PDTC组大鼠病灶周边呈缺血性改变,神经元体积轻度缩小,呈均匀淡红色,细胞核固缩,细胞核、质分离,正常结构及核仁皆消失,神经炎症局限化。对照组及假手术组大鼠脑组织无明显β-APP和GFAP表达,TBI组和PDTC组大鼠脑组织中均可见β-APP、GFAP在神经元浆膜下和(或)轴突处积累。与TBI组比较,PDTC组大鼠大脑皮质β-APP和GFAP阳性染色体神经元细胞数减少、表达强度减弱。假手术组、TBI组和PDTC组大鼠脑组织中NF-κB P65蛋白相对表达量显著高于对照组,PDTC组大鼠脑组织中NF-κB P65蛋白相对表达量显著高于TBI组(P<0.05)。PDTC组和假手术组大鼠脑组织中磷酸化NF-κB P65蛋白相对表达量显著低于对照组,TBI组大鼠脑组织中磷酸化NF-κB P65蛋白相对表达量显著高于对照组和假手术组,PDTC组大鼠脑组织中磷酸化NF-κB P65蛋白相对表达量显著低于TBI组和假手术组(P<0.05)。假手术组与对照组大鼠脑组织中IκB蛋白相对表达量比较差异无统计学意义(P>0.05);TBI组大鼠脑组织中IκB蛋白相对表达量显著高于对照组,PDTC组大鼠脑组织中IκB蛋白相对表达量显著低对照组、假手术组和TBI组(P<0.05)。TBI组大鼠脑组织中磷酸化IκB蛋白相对表达量显著低于对照组和假手术组,PDTC组大鼠脑组织中磷酸化IκB蛋白相对表达量高于TBI组(P<0.05)。假手术组大鼠脑组织中NLRP3蛋白相对表达量显著高于对照组,TBI组和PDTC组大鼠脑组织中NLRP3蛋白相对表达量显著低于假手术组和对照组,TBI组大鼠脑组织中NLRP3蛋白相对表达量显著低于PDTC组(P<0.05)。假手术组、PDTC组及TBI组大鼠脑组织中caspase-1蛋白相对表达量显著高于对照组,PDTC组大鼠脑组织中caspase-1蛋白相对表达量显著低于TBI组(P<0.05)。PDTC组、TBI组、假手术组大鼠脑组织中NF-κB P65 mRNA相对表达量显著高于对照组,PDTC组和TBI组大鼠脑组织中NF-κB P65 mRNA水平显著高于假手术组,PDTC组大鼠脑组织中NF-κB P65 mRNA相对表达量显著低于TBI组(P<0.05)。PDTC组和TBI组大鼠脑组织中IκB mRNA相对表达量显著低高对照组,假手术组大鼠脑组织中IκB mRNA表达显著低于对照组(P<0.05);PDTC组和TBI组大鼠脑组织中IκB mRNA相对表达量显著高于假手术组,PDTC组大鼠脑组织中IκB mRNA相对表达量显著低于TBI组(P<0.05)。PDTC组和TBI组大鼠脑组织中NLRP3 mRNA相对表达量显著高于对照组,假手术组大鼠脑组织中NLRP3 mRNA相对表达量显著低于对照组,PDTC组和TBI组大鼠脑组织中NLRP3 mRNA相对表达量显著高于假手术组,PDTC组大鼠脑组织中NLRP3 mRNA相对表达量显著低于TBI组(P<0.05)。假手术组、TBI组、PDTC组大鼠脑组织中caspase-1 mRNA相对表达量显著低于对照组,TBI组、PDTC组大鼠脑组织中caspase-1 mRNA相对表达量显著高于假手术组(P<0.05)。结论PDTC可有效改善TBI大鼠神经功能缺损评分、减轻神经炎症损伤,其机制可能通过调节NF-κB/NLRP3轴相关炎症损伤指标mRNA和蛋白表达及调控下游炎症因子而发挥作用。

Objective To investigate the effect and mechanism of ammonium pyrrolidine dithiocarbamate(PDTC)on neuroinflammatory injury in the penumbra of traumatic brain injury(TBI)in rats.Methods Sixty Sprague Dawley rats were divided into the PDTC group,TBI group,sham operation group and control group according to the random number table method,with 15 rats in each group.Rats in the PDTC group were intraperitoneally injected with PDTC(100 mg·kg-1)at 15 minutes before surgery;while the rats in the TBI group,sham operation group,and control group were intraperitoneally injected with the same volume of double distilled water.After the cranial window of rats in the TBI group and PDTC group was created,a 2.5 g steel rod with an inner diameter of 6.0 mm was dropped freely from a height of 75 cm through a transparent polyvinyl chloride tube with an inner diameter of 7.0 mm to impact the dura mater and induce right parietal lobe contusion and laceration to establish the TBI model;rats in the sham operation group were sealed with bone wax after the cranial window creation,without any impact applied;rats in the control group were raised under normal conditions.The modified neurological severity score(mNSS)was used to evaluate the degree of neurobehavioral damage in rats in each group at 1,4 and 7 days after modeling.At 2 days after modeling,5 rats in each group were decapitated,and brain tissues were taken for hematoxylin&eosin(HE)staining,and morphological changes of the brain tissues were observed under an optical microscope.The expressions ofβ-amyloid precursor protein(β-APP)and glial fibrillary acidic protein(GFAP)in the brain tissues of rats in each group were detected by immunohistochemical staining.At 24 hours after modeling,5 rats in each group were decapitated,and the right injured penumbra tissues were obtained;the expressions of nuclear transcription factor-κB(NF-κB)P65,phosphorylated NF-κB P65,inhibitor of NF-κB(IκB),phosphorylated IκB,NOD-like receptor protein 3(NLRP3)and caspase-1 protein in the right injured penumbra tissue of rats in each group were detected by Western blot,and the expressions of NF-κB P65,IκB,NLRP3 and caspase-1 mRNA in the right injured penumbra tissue of rats in each group were determined by real-time quantitative polymerase chain reaction.Results At 1,4,and 7 days after modeling,the mNSS scores of rats in the TBI group were significantly higher than those in the PDTC group,control group and sham operation group.The mNSS scores of rats in the PDTC group were significantly higher than those in the control group and sham operation group(P<0.05);there was no statistically significant difference in mNSS scores between the sham operation group and the control group(P>0.05).The neurons and neurogliocyte of rats in the control group and the sham operation group exhibited normal morphology,without swelling and widening of intercellular space.Diffuse hemorrhagic changes were observed in the brain tissues of rats in the TBI group,with different morphologies of neuronal cell body,unclear cell membrane and cytoplasm,pyknosis of cell nuclei,often triangular shape,disappearance of normal structure and nucleoli,and diffuse white blood cells and red blood cells filling the field of vision.The lesion surrounding area of rats in the PDTC group showed ischemic changes,with mild shrinkage of neuronal volume,a uniform light red color,karyopyknosis,nuclear-cytoplasmic dissociation,disappearance of normal structure and nucleoli,and localization of neuroinflammation.There was no significant expression ofβ-APP and GFAP in the cerebral cortex of rats in the control group and the sham operation group,while the accumulation ofβ-APP and GFAP in neuronal serosae and/or axons was observed in the brain tissues of rats in the TBI group and the PDTC group.Compared with the TBI group,a decrease in the number and the expression intensity ofβ-APP and GFAP-positive stained neuronal cells in the cerebral cortex of rats was observed in the PDTC group.The relative expression of NF-κB P65 protein in the brain tissues of rats in the sham operation group,TBI group and PDTC group was significantly higher than that in the control group,and the relative expression of NF-κB P65 protein in the brain tissues of rats in the PDTC group was significantly higher than that in the TBI group(P<0.05).The relative expression of phosphorylated NF-κB P65 protein in the brain tissues of rats in the PDTC group and the sham operation group was significantly lower than that in the control group,the relative expression of phosphorylated NF-κB P65 protein in the brain tissues of rats in the TBI group was significantly higher than that in the control group and the sham operation group,and the relative expression of phosphorylated NF-κB P65 protein in the brain tissues of rats in the PDTC group was significantly lower than that in both TBI group and sham operation group(P<0.05).There was no significant difference in the relative expression of IκB protein in the brain tissues of rats between the sham operation group and the control group(P>0.05);the relative expression of IκB protein in the brain tissues of rats in the TBI group was significantly higher than that in the control group,and the relative expression of IκB protein in the brain tissues of rats in the PDTC group was significantly lower than that in the control group,sham operation group,and TBI group(P<0.05).The relative expression of phosphorylated IκB protein in the brain tissues of rats in the TBI group was significantly lower than that in the control group and the sham operation group,and the relative expression of phosphorylated IκB protein in the brain tissues of rats in the PDTC group was significantly higher than that in the TBI group(P<0.05).The relative expression of NLRP3 protein in the brain tissues of rats in the sham operation group was significantly higher than that in the control group,the relative expression of NLRP3 protein in the brain tissues of rats in the TBI group and the PDTC group was significantly lower than that in the sham operation group and the control group,and the relative expression of NLRP3 protein in the brain tissues of rats in the TBI group was significantly lower than that in the PDTC group(P<0.05).The relative expression of caspase-1 protein in the brain tissues of rats in the sham operation group,PDTC group,and TBI group was significantly higher than that in the control group,and the relative expression of caspase-1 protein in the brain tissues of rats in the PDTC group was significantly lower than that in the TBI group(P<0.05).The relative expression of NF-κB P65 mRNA in the brain tissues of rats in the PDTC group,TBI group,and sham operation group was significantly higher than that in the control group,the relative expression of NF-κB P65 mRNA in the brain tissues of rats in the PDTC group and TBI group was significantly higher than that in the sham operation group,and the relative expression of NF-κB P65 mRNA in the brain tissues of rats in the PDTC group was significantly lower than that in the TBI group(P<0.05).The relative expression of IκB mRNA in the brain tissues of rats in the PDTC group and TBI group were significantly higher than that in the control group,and the expression of IκB mRNA in the brain tissues of rats in the sham operation group was significantly lower than that in the control group(P<0.05).The relative expression of IκB mRNA in the brain tissues of rats in the PDTC group and TBI group was significantly higher than that in the sham operation group,and the relative expression of IκB mRNA in the brain tissues of rats in the PDTC group was significantly lower than that in the TBI group(P<0.05).The relative expression of NLRP3 mRNA in the brain tissues of rats in the PDTC group and TBI group was significantly higher than that in the control group,the relative expression of NLRP3 mRNA in the brain tissues of rats in the sham operation group was significantly lower than that in the control group,the relative expression of NLRP3 mRNA in the brain tissues of rats in the PDTC group and TBI group was significantly higher than that in the sham operation group,and the relative expression of NLRP3 mRNA in the brain tissues of rats in the PDTC group was significantly lower than that in the TBI group(P<0.05).The relative expression of caspase-1 mRNA in the brain tissues of rats in the sham operation group,TBI group,and PDTC group was significantly lower than that in the control group,the relative expression of caspase-1 mRNA in the brain tissues of rats in the TBI group and PDTC group was significantly higher than that in the sham operation group(P<0.05).Conclusion PDTC can effectively improve neural functional deficit score and reduce neuroinflammatory injury in TBI rats,the mechanism of which may be related to regulating mRNA and protein expression of NF-κB/NLRP3 axis-related inflammatory injury indicators and regulating downstream inflammatory factors.