Microinjection of a growth factor cocktail affects activated microglia in the neocortex of adult rats

Microglia, as the resident immune cells in the central nervous system, play important roles in regulating neuronal processes, such as neural excitability, synaptic activity, and apoptotic cell clearance. Growth factors can activate multiple signaling pathways in central nervous system microglia and can regulate their immune effects, but whether growth factors can affect the morphological characteristics and ultrastructure of microglia has not been reported. After microinjecting 300 nL of a growth factor cocktail, including 10 μg/mL epidermal growth factor, 10 μg/mL basic fibroblast growth factor, 10 μg/mL hepatocyte growth factor and 10 μg/mL insulin-like growth factor into adult rat cortex, we found that the number of IBA1-positive microglia around the injection area increased significantly, indicating local activation of microglia. All CD68-positive labeling co-localized with IBA1 in microglia. Cell bodies and protrusions of CD68-positive cells were strongly attached to or were engulfing neurons. Characteristic huge phagosomes were observed in activated phagocytes by electron microscopy. The phagosomes generally included non-degraded neuronal protrusions and mitochondria, yet they contained no myelin membrane or remnants, which might indicate selective phagocytosis by the phagocytes. The remnant myelin sheath after phagocytosis still had regenerative ability and formed "myelin-like" structures around phagocytes. These results show that microinjection of a growth factor cocktail into the cerebral cortex of rodents can locally activate microglia and induce selective phagocytosis of neural structures by phagocytes. The study was approved by the Institute of Laboratory Animal Science, Beijing Institute of Basic Medical Sciences(approval No. IACUC-AMMS-2014-501) on June 30, 2014.     

Effects of High-Voltage Pulsed Radiofrequency on the Ultrastructure and Nav1.7 Level of the Dorsal Root Ganglion in Rats With Spared Nerve Injury

ObjectivesTo investigate the analgesic effect of high-voltage pulsed radiofrequency (HV-PRF) on the dorsal root ganglion (DRG) for neuropathic pain induced by spared nerve injury (SNI) in rats, especially the influence of this treatment on the DRG ultrastructure and voltage-gated sodium channel 1.7 (Nav1.7) level in the DRG.Materials and MethodsOne hundred fifty adult male Sprague-Dawley rats were randomly divided into five groups: Sham, SNI, Free-PRF, standard-voltage PRF (SV-PRF), and HV-PRF. The 45V-PRF and 85V-PRF procedures applied to the left L5 DRG were performed in SV-PRF group and the HV-PRF group, respectively, on day 7 after SNI, whereas no PRF was concurrently delivered in Free-PRF group. The paw mechanical withdrawal threshold (PMWT) was detected before SNI (baseline) and on days 1, 3, 7, 8, 10, 14, and 21. The changes of left L5 DRG ultrastructure were analyzed with transmission electron microscopy on days 14 and 21. The expression levels of Nav1.7 in left L5 DRG were detected by immunofluorescence and Western blot.ResultsCompared with the Free-PRF group, PMWT in the SV-PRF group and HV-PRF group were both significantly increased after PRF (all p < 0.05). Meanwhile, the PMWT was significantly higher in the HV-PRF group than that in the SV-PRF group on days 14 and 21 (all p < 0.05). There were statistically significant differences between the SV-PRF and Free-PRF groups (p < 0.05). Similarly, statistically significant difference was found between the HV-PRF and Free-PRF groups (p < 0.05). Especially, comparison of the SV-PRF group and the HV-PRF group revealed statistically significant difference (p < 0.05). The Nav1.7 levels were significantly downregulated in the SV-PRF group and HV-PRF groups compared to that in the Free-PRF group (all p < 0.01). A significantly lower Nav1.7 level was also found in the HV-PRF group compared to that in the SV-PRF group (p < 0.05).ConclusionsThe HV-PRF produces a better analgesic effect than SV-PRF applied to the DRG in SNI rats. The underlying mechanisms may be associated with improving the histopathological prognosis and the downregulation of Nav1.7 levels in the DRG.     

前庭器官超微结构研究及结构图构建

目的通过扫描电镜观察小鼠椭圆囊、球囊、壶腹超微结构,研究分析并据此构建前庭器官新的结构示意图。方法选取3个年龄段小白鼠各10只,分别是年轻组≤2个月、中年组2~12个月、老龄组>12个月。分离出椭圆囊、球囊、壶腹,采用扫描电镜技术样品制备方法制备样品,应用扫描电镜进行样品观察。结果扫描电镜下可以得到:①椭圆囊斑及球囊斑不同层面图片:表面为堆积并相互黏附的"表面耳石",表面耳石下是无结构胶状质;底层表面耳石深入到无结构胶质层里;无结构胶质层下面是毛细胞纤毛及"纤毛间耳石"层,不同纤毛束之间均有纤毛间耳石存在,立于支持细胞表面,表面平坦;蜂窝状胶质物质联接无结构胶质层、纤毛间耳石及毛细胞纤毛。②壶腹超微结构的图片:嵴帽是无结构的胶状质与壶腹外侧壁紧贴,但较易分离,嵴帽和壶腹外侧壁之间有纤细的晶状体物质,在壶腹嵴两侧壁上也有纤细晶体物质(壶腹嵴表面耳石);不同的毛细胞纤毛之间有耳石结构的存在(壶腹嵴纤毛间耳石)。结论通过对前庭器官扫描电镜的观察,发现了椭圆、球囊斑及壶腹的新结构成分,由此构建出新的前庭器官超微结构示意图。     

Structural adaption of axons during de‐ and remyelination in the Cuprizone mouse model

Multiple Sclerosis is an autoimmune disorder causing neurodegeneration mostly in young adults. Thereby, myelin is lost in the inflammatory lesions leaving unmyelinated axons at a high risk to degenerate. Oligodendrocyte precursor cells maintain their regenerative capacity into adulthood and are able to remyelinate axons if they are properly activated and differentiate. Neuronal activity influences the success of myelination indicating a close interplay between neurons and oligodendroglia. The myelination profile determines the distribution of voltage‐gated ion channels along the axon. Here, we analyze the distribution of the sodium channel subunit Nav1.6 and the ultrastructure of axons after cuprizone‐induced demyelination in transgenic mice expressing GFP in oligodendroglial cells. Using this mouse model, we found an increased number of GFP‐expressing oligodendroglial cells compared to untreated mice. Analyzing the axons, we found an increase in the number of nodes of Ranvier in mice that had received cuprizone. Furthermore, we found an enhanced portion of unmyelinated axons showing vesicles in the cytoplasm. These vesicles were labeled with VGlut1, indicating that they are involved in axonal signaling. Our results highlight the flexibility of axons towards changes in the glial compartment and depict the structural changes they undergo upon myelin removal. These findings might be considered if searching for new neuroprotective therapies that aim at blocking neuronal activity in order to avoid interfering with the process of remyelination.     

“标本配穴”电针对慢性心肌缺血模型大鼠线粒体结构及呼吸酶活性的影响

目的:以心肌线粒体为切入,观察“标本配穴”电针对慢性心肌缺血模型大鼠心肌线粒体结构、GAPDH、CS、CCO的酶活性及心肌组织ATP含量的影响,探讨“标本配穴”电针对慢性心肌缺血模型大鼠心肌线粒体的保护机制。方法:将30只Wistar雄性大鼠随机分为空白组、模型组、标本配穴组,每组10只。模型组、标本配穴组大鼠皮下注射盐酸异丙肾上腺素制备慢性心肌缺血大鼠模型。标本配穴组在造模结束后取“内关”“足三里”“关元”电针干预10 min,疏密波,2~100 Hz,1 mA,连续21天。运用透射电镜观察心肌线粒体结构变化,采用试剂盒检测3-磷酸甘油醛脱氢酶(GAPDH)、柠檬酸合成酶(CS)、细胞色素C氧化酶(CCO)的酶活性及心肌组织ATP含量。结果:与空白组比较,模型组线粒体结构破坏明显,大部分线粒体出现变形空泡化;而与模型组比较,标本配穴组线粒体结构损伤程度明显减轻。与空白组相比,模型组、标本配穴组心肌组织ATP含量、GAPDH、CS、CCO活性均明显降低(P<0.01)。但与模型组相比,标本配穴组4指标均显著增高(P<0.01),且心肌组织ATP含量与GAPDH、CS、CCO活性成线性相关。结论:在慢性心肌缺血状态下,标本配穴电针可提升线粒体呼吸酶活性,增加有氧呼吸产能效率,改善心脏能量代谢,从而减轻心肌细胞的结构破坏,对心肌组织起到保护作用。     

丙酮酸乙酯对宫内感染致脑损伤新生仔鼠AQP4表达和脑组织超微结构的影响

目的 研究丙酮酸乙酯(EP)对宫内感染致新生仔鼠脑损伤水通道蛋白4(AQP4)表达和脑组织超微结构的影响。方法 选取36只孕鼠随机分为 LPS组(n=12)、EP组(n=12)、NS组(n=12)。LPS组:孕17 d、18 d连续两天腹腔注射 LPS 380 μg/kg;EP组:同法制备孕鼠宫内感染模型,并在注射LPS后立即给予孕鼠腹腔注射 EP 40 mg/kg;NS组:腹腔注射同等量生理盐水。对孕鼠分娩后的胎盘和新生仔鼠脑组织进行HE染色观察宫内感染和脑损伤情况。剔除早产鼠,各组随机选取新生仔鼠36只,于生后12、24、48 h对脑组织进行免疫组织化学染色,观察AQP4的表达;电镜观察脑组织超微结构的变化。结果 与NS组比较,LPS组孕鼠胎盘组织可见大量的炎性细胞浸润,有宫内感染,LPS组仔鼠HE染色提示有脑损伤;与LPS组相比较,EP组仔鼠出生后24 h、48 h脑组织AQP4的表达量均低于LPS组(P<0.05);电镜下LPS组神经细胞超微结构显示损伤严重。结论 丙酮酸乙酯对宫内感染致脑损伤新生仔鼠的脑组织具有一定的神经保护作用,可能与AQP4表达水平有关。     

不同来源牛黄与雄黄配伍的牛黄解毒片对小鼠毒性的影响

目的:比较不同来源牛黄与雄黄配伍的牛黄解毒片对小鼠的毒性反应,探讨临床上牛黄解毒片引起慢性砷中毒的机制。方法:按2015年版《中国药典》的配方用天然牛黄、人工牛黄、体外培育牛黄分别制成牛黄解毒片,并用同法制成无牛黄成分、无雄黄成分的缺味组,另设同剂量单味雄黄作为对照,每种牛黄解毒片组再分为0.5,1.0,2.0 g·kg~(-1)剂量组,单味雄黄组分为0.06,0.12,0.24 g·kg~(-1)剂量组,对ICR小鼠进行灌胃给药28 d,观察毒性反应;给药结束后解剖取血,分离血清检测肝肾功能,取心、肝、脾、肺、肾做组织病理学检查和电镜下超微结构观察。结果:给药期间各给药组未观察到毒性反应,给药结束亦未观察到大体内脏及体表皮肤病变,血液生化指标检查未能明确雄黄对肝肾的毒性作用。组织病理学和电镜下超微结构检查各牛黄解毒片组未发现异常毒性病理改变,但苏木素-伊红(HE)染色显示单味雄黄高剂量组肝脏出现小叶中心性肝细胞肥大和糖原聚集,过碘酸希夫(PAS)染色表明肝细胞内糖原聚集,电镜下超微结构检查发现肝细胞内局灶性胞浆溶解,内有数量不等糖原颗粒,提示雄黄可致小鼠肝脏毒性。结论:用不同来源牛黄与雄黄配伍的牛黄解毒片对小鼠进行28 d灌胃给药,均未发现对小鼠有明显的毒性反应。而用单味雄黄却引起肝脏毒性,提示牛黄解毒片中的其他成分与雄黄配伍能显著降低可溶性砷和价态砷的含量,从而降低雄黄的毒性。     

Laminin and collagen IV distribution and ultrastructure of the basement membrane of the gingiva of the rat incisor

The continuous growth of the rat incisor is associated with renovation of the junctional epithelium and resorption of the periodontal ligament. The circumdental papilla separates the connective tissue suffering resorption from the rest of the gingiva. Laminin and collagen IV were detected by the immunoperoxidase technique on the basement membrane of all regions of the gingival epithelium of the rat incisor, except the internal basal lamina and the internal surface of the circumdental papilla. The internal basal lamina is formed by a granular electron-dense material, without the organization of a typical basal lamina. Areas of the internal surface of the circumdental papilla, negative for laminin and collagen IV, lack the basal lamina. These data suggest that these molecules are not components of the dento-epithelial junction of the distal surface of the rat incisor. In addition, the basal lamina is absent or fragmented on the internal surface of the circumdental papilla, adjacent to the areas of the connective tissue undergoing resorption.     

Ultracytochemical localization of basal lamina anionic sites in the rat epithelial attachment apparatus

The basal lamina anionic sites of the epithelial attachment apparatus (EAA) were investigated at the electron microscopic level in adult rat periodontium. After 1M NaCl junctional epithelium detachment, an irregular and fluffy basal lamina-like structure appeared to cover the cementum surface. This structure reacted positively with polyethyleneimine (PEI), a strongly cationized ultrastruc-tural tracer, appearing to be composed of highly electron-dense microaggregates. Depending on section plane, double-tracked structures of undefined length were found within PEI precipitates and closely related to cementum collagen fibrils. After nitrous acid de-N-sulphation, 8 nm wide sets of two parallel lines were clearly identified. "Double tracks", i.e., sets of paired lines with peripherical PEI electron-dense material, were found to self-assemble to form dimers, clusters or more complex organizational patterns. From sensitivity towards nitrous acid oxidation and positive control observations, it was concluded that basal lamina anionic sites in the EAA. represented by PEI microaggregates, contain heparan sulfate proteoglycans (HSPGs). Furthermore, high resolution ultrastructural images demonstrated that HSPGs adopt a morphological appearance of "double tracks" in the tissue. On the other hand, the present findings suggest that HSPGs clusters, never found in the mucosal basement membrane used as positive control, may be related to a functional specificity of the tissue at the dento-gingival junction.