Astrocytes in the damaged brain: Molecular and cellular insights into their reactive response and healing potential

Long considered merely a trophic and mechanical support to neurons, astrocytes have progressively taken the center stage as their ability to react to acute and chronic neurodegenerative situations became increasingly clear. Reactive astrogliosis starts when trigger molecules produced at the injury site drive astrocytes to leave their quiescent state and become activated. Distinctive morphological and biochemical features characterize this process (cell hypertrophy, upregulation of intermediate filaments, and increased cell proliferation). Moreover, reactive astrocytes migrate towards the injured area to constitute the glial scar, and release factors mediating the tissue inflammatory response and remodeling after lesion. A novel view of astrogliosis derives from the finding that subsets of reactive astrocytes can recapitulate stem cell/progenitor features after damage, fostering the concept of astroglia as a promising target for reparative therapies. But which biochemical/signaling pathways modulate astrogliosis with respect to both the time after injury and the type of damage? Are reactive astrocytes overall beneficial or detrimental for neuroprotection and tissue regeneration? This debate has been animating this research field for several years now, and an integrated view on the results obtained and the possible future perspectives is needed. With this Commentary article we have attempted to answer the above-mentioned questions by reviewing the current knowledge on the molecular mechanisms controlling and sustaining the reaction of astroglia to injury and its stem cell-like properties. Moreover, the cellular/molecular mechanisms supporting the detrimental or beneficial features of astrogliosis have been scrutinized to gain insights on possible pharmacological approaches to enhance astrocyte neuroprotective activities.     

去甲斑蝥素对G422脑胶质瘤抑制作用的体内研究

目的:研究去甲斑蝥素(NCTD)体内对脑胶质瘤G422细胞的抑制作用。方法:建立G422细胞小鼠移植瘤模型,将荷瘤小鼠随机分为模型组、CTX阳性对照组及NCTD高、中、低剂量组(100、50、25 mg.kg-1),每组10只,另设10只为正常对照组,正常对照组每日给生理盐水灌胃,CTX和NCTD组采用腹腔注射方式给药,10 d后双抗体夹心ABC-ELISA法测sIL-2R的含量;酶联免疫ELISA法测IFN-γ含量;剥瘤,计算抑瘤率;剥瘤的同时取脾脏,计算脾脏指数;MTT法检测NCTD对荷瘤小鼠脾脏T、B淋巴细胞增殖的影响。结果:NCTD可降低荷瘤小鼠血清sIL-2R含量,提高IFN-γ含量,抑制G422细胞小鼠移植瘤的生长;对脾脏指数影响较少,可促进荷瘤小鼠的T、B淋巴细胞增殖。结论:NCTD体内外可抑制G422细胞生长,并具有免疫调节作用。     

人参三七川芎提取物对增龄和高血压大鼠血管平滑肌细胞的影响

目的 观察和比较增龄与高血压对大鼠主动脉血管平滑肌细胞(vascular smooth muscle cells,VSMCs)的影响及人参、三七、川芎提取物的干预作用。方法 采用原代细胞培养的方法建立大鼠主动脉VSMCs模型,其中增龄实验分5组：青年对照组(Yon组)、老龄组(Old组)、老龄+普罗布考组(Old+Pro组)、老龄+中药低剂量组(Old+Low组)和老龄+中药高剂量组(Old+High组);高血压实验分5组：Wistar-Kyoto对照组(WKY组)、自发性高血压大鼠(spontaneously hypertensive rat,SHR)组、SHR+缬沙坦组(SHR+Val组)、SHR+中药低剂量组(SHR+Low组)和SHR+中药高剂量组(SHR +High组)。采用MTT法检测细胞增殖,免疫细胞化学法检测基质金属蛋白酶-9(MMP-9)表达,RT-PCR和Western blot分别检测过氧化物酶增殖物激活受体γ(peroxisome proliferator activated receptor-γ,PPAR-γ)mRNA和蛋白表达。结果 与Yon组比较,Old组VSMCs增殖水平和MMP-9表达升高,PPAR-γ mRNA和蛋白表达减少,差异均有统计学意义(P<0.05)。与Old组比较,Old+Pro组、Old+High组和 Old+Low组VSMCs增殖水平和MMP-9表达明显降低,PPAR-γ mRNA表达明显增加(均P<0.05),Old+Pro组和Old+Low组PPAR-γ蛋白表达明显增加(均P<0.05)。与WKY组比较,SHR组VSMCs增殖水平和MMP-9表达明显升高,PPAR-γ mRNA和蛋白表达明显减少(均P<0.05);与SHR组比较,SHR+Val组、SHR +High组和SHR+Low组VSMCs增殖水平和MMP-9表达明显降低,PPAR-γ mRNA和蛋白表达增加(均P<0.05)。结论 增龄和高血压均可造成大鼠主动脉VSMCs过度增殖及相关细胞活性因子的表达改变,中药人参、三七、川芎提取物能够降低其增殖水平,减少负性细胞因子的表达以降低增龄和高血压对VSMCs的损害,延缓血管细胞的老化。     

The bark of Betula platyphylla var. japonica inhibits the development of atopic dermatitis-like skin lesions in NC/Nga mice

The bark of Betula platyphylla Sukat. var. japonica Hara (Asian White Birch, AWB) is one of the herbs used in Eastern countries for the treatment of various inflammatory diseases including atopic dermatitis (AD). The present study was performed to examine if and how the bark of AWB inhibits the development of AD-like skin lesions in NC/Nga mice induced by repeated application of picryl chloride (PC). With this aim, we examined the skin symptom severity, itching behavior, serum immunoglobulin (Ig) E level and mRNA expression of cytokines at iliac and cervical lymph nodes in the mice. Oral administration of AWB extracts (25, 100 and 250 mg/kg) to the PC-treated mice inhibited the development of AD-like skin lesions as exemplified by a significant decrease in the total skin severity scores, itching behavior and a decrease in hypertrophy and infiltration of inflammatory cells into dermis. The serum IgE level was also significantly reduced by AWB extract. In the RT-PCR results, the expression of interleukin-4 mRNA was reduced by AWB extract, whereas the expression of interferon-gamma mRNA was not changed. These results suggest that AWB inhibits the development of AD-like skin lesions in NC/Nga mice through the suppression of the T-helper 2 cell response.     

经前平颗粒对经前期综合征肝气逆证模型大鼠不同脑区γ-氨基丁酸A受体结合活性的影响

目的 通过检测经前期综合征（premenstrual syndrome,PMS）肝气逆证模型大鼠大脑皮质和海马γ-氨基丁酸A受体（GABA_AR）结合活性变化,探讨中药经前平颗粒对PMS肝气逆证的干预作用。方法 多因素综合刺激法复制PMS肝气逆证大鼠模型。放射性配体受体结合技术测定大鼠皮质和海马GABA_AR的结合活性变化。结果 与正常组相比,肝气逆证造模组大鼠大脑皮质和海马GABA_AR结合活性均明显增加。与模型组相比,经前平颗粒组大鼠皮质和海马GABA_AR活性均明显下降。结论 大鼠皮质和海马GABA_AR结合活性增加可能是PMS肝气逆证的重要机制之一。中药经前平颗粒可对GABA_AR 结合活性含量异常变化起到调节作用。     

实验性自身免疫性重症肌无力小鼠免疫功能状态的研究

目的：探讨实验性自身免疫性重症肌无力（EAMG）模型小鼠免疫应答特点。方法：根据临床症状及重复电刺激试验结果将造模小鼠分为成模组及未成模组,检测其免疫功能状态的改变,包括血清中乙酰胆碱受体抗体（AchRab）的水平,脾脏CD4^＋T细胞数量,用淋巴细胞增殖试验检测脾细胞经刀豆蛋白A（ConA）活化的非特异增殖能力,检测脾脏T细胞因子白细胞介素4（IL-4）,干扰素γ（IFN-γ）分泌水平。并与弗氏佐剂（CFA）对照组及正常对照组进行比较。结果：与未成模组、弗氏佐剂对照组及正常对照组相比,成模组小鼠AchRab显著增高,脾脏CD4^＋T细胞数升高;外周脾细胞对ConA刺激的非特异性增殖能力显著升高;脾脏T细胞细胞因子IL-4,IFN-γ显著升高,（均P〈0.01）,IFN-γ升高的程度高于IL-4（P〈0.01）。结论：EAMG发生是一个自身免疫应答参与的过程,体液免疫、细胞免疫应答参与了EAMG的发生。     

丙型肝炎患者生化变量与细胞因子间的相关性分析

目的：研究丙型肝炎病毒感染后血液生化变量与细胞因子重组人干扰素γ（interferon-1,IFN-γ）、肿瘤坏死因子仪（tumornecrosisfactor,TNF—α）、重组人白介素10（interleukin-10,IL-10）之间的相关性。方法：以66例丙型肝炎患者为材料,利用统计学软件,分析丙型肝炎患者各生化指标之间及与3种细胞因子间的相关性。结果：①除球蛋白（GLO）与TNF—d在0．05置信水平上有较低相关性（r=-0．287,P=0．046）之外,各生化变量与各细胞因子之间无明显相关性。②各生化变量之间,丙氨酸氨基转换酶（ALT）与天门冬酸氨基转换酶（AST）有显著的相关性（r=0．869,P=0）,做除法后（ALT／AST）相关性基本被消除,各变量之间存在微弱互相关性。③除IFN-γ与TNF—α之间存在弱相关性（r=-0．448,P=0．009）之外,各炎症细胞因子之间无明显相关性。结论：各生化指标之间、3种炎症细胞因子之间、各生化变量与3种炎症细胞因子间的相关性均较差。     

术后认知功能障碍治疗的新靶向-γ-氨基丁酸A型受体相关药物

背景 术后认知功能障碍(postoperative cognitive dysfunction,POCD)是一种常见的围术期并发症.γ-氨基丁酸A型(γ-aminobutyricacid type A,GABAA)受体作为一种中枢神经抑制性受体,可能对POCD的发生起着关键性作用.目的 综述以GABAA受体为靶点的相关药物对POCD的影响.内容 与GABAA受体相关的3类药物:激动剂、拮抗剂和反向激动剂,对POCD可分别产生诱发、逆转和改善症状的作用. 趋向 对记忆或者认知功能损害具有改善作用的GABAA受体相关药物,对POCD的治疗具有重大意义,将成为今后POCD的研究热点.