Tunneling nanotubes between rat primary astrocytes and C6 glioma cells alter proliferation potential of glioma cells

The tunneling nanotube(TNT) is a newly discovered, long and thin tubular structure between cells. In this study, we established a co-culture system for rat primary astrocytes and C6 glioma cells and found that TNTs formed between them. Most of the TNTs initiated from astrocytes towards C6 glioma cells. The formation of TNTs depended on p53. In addition, hydrogen peroxide increased the number of TNTs in the co-culture system. Established TNTs reduced the proliferation of C6 glioma cells. Our data suggest that TNTs between astrocytes and glioma cells facilitate substance transfer and therefore alter the properties, including the proliferation potential, of glioma cells.     

Immunocytochemical localization of somatostatin receptor sst2A in the rat spinal cord and dorsal root ganglia

Intrathecal administration of octreotide, a stable somatostatin analogue, provides pain relief in patients, and locally applied somatostatin inhibits firing of nociceptive dorsal horn neurons. In the present study, we have raised polyclonal antibodies that specifically detect the somatostatin receptor sst_2A and used these antisera for immunocytochemical localization of the receptor protein in the rat spinal cord and dorsal root ganglia. In the superficial layers of the dorsal horn, sst_2A-like immunoreactivity (Li) formed a dense network consisting of neuronal perikarya and dendrites which were often closely apposed by, but not co-contained within, somatostatin-14-immunoreactive nerve fibres and terminals. sst_2A-Li was resistant to dorsal rhizotomy and did not colocalize with either substance P or calcitonin gene-related peptide suggesting that sst_2A-Li was not located to primary afferents, but rather confined to second-order spinal neurons. The position of sst_2A-Li perikarya and dendrites in the dorsal horn appeared to be similar to those containing μ-opioid receptor-Li; however, double labelling experiments revealed no instances of coexistence of these two receptors. sst_2A-Li was also observed in the dorsal root ganglia predominantly targeted to the somatic plasmalemma of medium size neurons distinct from those expressing somatostatin-14 or δ-opioid receptors. Thus, the present results not only provide a morphological substrate for spinal octreotide analgesia but also show that somatostatin and opioids are poised to modulate nociceptive transmission by distinct anatomical systems.     

Is the effect of somatostatin on muscarinic receptors selective to M1 type?

The effect of somatostatin on muscarinic receptors (mAchR) was investigated through saturation experiments of [3H]oxotremorine-M-acetate and oxotremorine/[3H]N-methyl-scopolamine competition experiments. Somatostatin converted oxotremorine high affinity binding sites to low affinity sites in the hippocampus and cerebral cortex whose mAchR were dominantly of M1 type. Somatostatin did not alter agonist binding in the medulla-pons where M2 receptors were abundant. Therefore, the effect of somatostatin on mAchR seems to be selective to high affinity binding sites of M1 receptors.     

IGF-IR反义寡核苷酸对胶质瘤细胞增殖的影响

目的 根据胰岛素样生长因子-受体（IGF-IR）基因序列设计了IGF-IR mRNA起始密码子下游的硫代磷酸型反义寡核苷酸和正义寡核苷酸，研究其对C6胶质瘤细胞增殖作用。方法 实验分为反义核酸组、正义核酸组和空白对照组，经细胞计数、MTT法研究反义核苷酸对胶质瘤细胞生长和增殖的抑制作用。并应用免疫细胞化学方法检测胶质瘤细胞IGF-IR和增殖细胞核抗原（PCNA）蛋白的表达。结果 反义寡核苷酸能有效地降低IGF-IR基因的表达，抑制体外培养的胶质瘤细胞的增殖，其抑制作用24h显效，96h仍有作用，反义寡核苷酸的抑制效果与其作用浓度有关。而正义寡核苷酸对其无抑制作用。同时可见反义寡核苷酸抑制增殖作用中，能明显下调PCNA蛋白的表达。结论 IGF-IR介导的IGF-I-IGF-IR的自（旁）分泌环对胶质瘤生长极其重要，通过IGF-IR反义寡核苷酸治疗能较有效地抑制胶质瘤细胞的增殖。     

Distribution and expression levels of somatostatin and somatostatin receptors in the ileum of normal and acutely Schistosoma mansoni-infected SSTR2 knockout/lacZ knockin mice

Abstract  We recently described the widespread expression of somatostatin (SOM) receptors (SSTRs) in the non-inflamed and inflamed murine ileum. Surprisingly, no significant changes were observed in the SSTR2 expression during intestinal inflammation. These data, combined with several recent independent lines of investigation, raised some question about the long presumed central role of SSTR2 in the SOM-mediated effects in the physiological and pathological activity of the gastrointestinal (GI) tract. To further unravel the role of SSTR2 in GI physiology, we studied the expression of SOM and SSTRs in the normal and inflamed SSTR2 knockout/ lacZ knockin ( SSTR2 ^−/− ) ileum. The SSTR2 ^−/− ileum was characterized by a widespread distribution of multiple SSTR subtypes in non-inflamed and inflamed conditions. Moreover, the absence of SSTR2 did not induce any compensatory effect in the distribution pattern or expression level of any of the other SSTR subtypes. In contrast, the amount of SOM mRNA was significantly lower in SSTR2 ^−/− ileum than that in wild type animals. Quantitative analysis revealed a decreased number of SOM-expressing neurons in both enteric plexuses of the knockout animals, implying a possible link between the number of SOM-expressing enteric neurons and the expression of SSTR2 in the enteric nervous system. In conclusion, these data show that a reconsideration of the role of SSTR2 in the GI somatostatinergic effects is in order and further corroborate recent data on the role of other SSTR subtypes in the inflammatory effects of SOM during intestinal inflammation.     

Ceramide in primary astrocytes from cerebellum: metabolism and role in cell proliferation

Cerebellar astrocytes are equipped with an efficient molecular machinery able to control the levels, and possibly the subcellular location, of ceramide. The major metabolic routes that contribute to the maintenance and variation of the cellular ceramide include ceramide biosynthesis, by de novo pathway or sphingosine recycling, ceramide formation from complex sphingolipids degradation and ceramide catabolism. In cerebellar astrocytes from rat cerebellum a peculiar metabolism of sphingomyelin occurs. This includes the preponderance of acidic sphingomyelinase, paralleled by a deficiency of the neutral Mg2+-dependent enzyme, as well as the presence of an extra-Golgi form of sphingomyelin synthase, which shares many characteristics with PC-PLC. Moreover these cells are characterized by a high efficiency in converting sphingosine to ceramide, possibly functional to the role played by astrocytes in the prevention of neuronal damage by high sphingosine concentration. Recent evidence demonstrates that a change of ceramide level is one of the key steps in the chain of reactions elicited by mitogenic stimuli. In fact, low cellular levels of ceramide characterize, and appear to be required for, the proliferation of cerebellar astrocytes. In particular mitogenic stimuli, such as basic fibroblast growth factor (bFGF), rapidly down regulate the cellular levels of ceramide by stimulating sphingomyelin synthase. Ceramide acts as an intracellular physiological inhibitor of cell growth, being able to counteract the effect of bFGF by inhibiting the MAP kinase pathway. Although many questions remain in this field, the present knowledge strongly supports that ceramide represents a crucial member within lipid mediators, involved in the signaling pathways underlying cell proliferation in cerebellar astrocytes.     

睫状神经营养因子对体外培养星形胶质细胞的激活作用(英文)

目的观察睫状神经营养因子(ciliary neurotrophic factor, CNTF)对体外培养星形胶质细胞的细胞激活作用。方法分别给予不同浓度(0、2、20、200 ng/ml)的CNTF孵育有血清培养和无血清培养的星形胶质细胞,采用免疫细胞化学技术及流式细胞术,观察星形胶质细胞形态及细胞周期的变化。结果有血清培养和无血清培养时CNTF均使星形胶质细胞GFAP表达增强,胞核增大。有血清培养时CNTF还可以促进星形胶质细胞进入细胞周期进行增殖;无血清培养时CNTF无此效应。结论无血清培养时CNTF可以刺激星形胶质细胞进入活化状态,但不刺激其增殖;有血清培养时CNTF可以协助血清中的丝裂原引起星形胶质细胞增殖。     

睫状神经营养因子对体外培养星形胶质细胞的激活作用

目的观察睫状神经营养因子（ciliary neurotrophic factor,CNTF）对体外培养星形胶质细胞的细胞激活作用。方法分别给予不同浓度（0、2、20、200ng／ml）的CNTF孵育有血清培养和无血清培养的星形胶质细胞,采用免疫细胞化学技术及流式细胞术,观察星形胶质细胞形态及细胞周期的变化。结果有血清培养和无血清培养时CNTF均使星形胶质细胞GFAP表达增强,胞核增大。有血清培养时CNTF还可以促进星形胶质细胞进入细胞周期进行增殖：无血清培养时CNTF无此效应。结论无血清培养时CNTF可以刺激星形胶质细胞进入活化状态,但不刺激其增殖：有血清培养时CNTF可以协助血清中的丝裂原引起星形胶质细胞增殖。     

Myelin basic protein stimulates the proliferation of astrocytes: possible explanation for multiple sclerosis plaque formation

In dissociated mouse brain cell cultures we frequently observed an association between myelin basic protein (MBP) positive oligo-dendrocytes and proliferating astrocytes. When MBP was added in a purified form to the culture medium, it greatly stimulated the proliferation of astrocytes, while other proteins tested did not. This finding allows us to speculate that the gliosis observed in demyelinating diseases or/and in central nervous system (CNS) injury would be due to the mitogenic effect exerted by MBP or its fragments when there is myelin breakdown.     

转录因子FOXR2对脑胶质瘤细胞增殖的影响

目的探讨下调或过表达FOXR2对脑胶质瘤细胞增殖能力的影响。方法以正常脑组织标本为模板,PCR法克隆FOXR2基因,并构建FOXR2过表达质粒;Western blot法检测FOXR2在胶质瘤细胞系中的表达水平。用慢病毒系统构建稳定下调及过表达FOXR2的脑胶质瘤细胞株;CCK8实验检测下调或过表达FOXR2对胶质瘤细胞增殖速率的影响。结果成功克隆FOXR2基因;WB检测结果显示稳定下调FOXR2的U251细胞株及过表达FOXR2的U87细胞株构建成功。CCK8实验结果表明,与对照组相比,96 h后下调FOXR2的胶质瘤细胞增殖速率减少45.13%;相反,过表达FOXR2后,胶质瘤细胞的增殖速率可增加43.98%。结论转录因子FOXR2可促进胶质瘤细胞的增殖。     

Differentiation of radial glia from radial precursor cells and transformation into astrocytes in the developing rat spinal cord

Radial glial cell origins and functions have been studied extensively in the brain; however, questions remain relating to their origin and fate in the spinal cord. In the present study, radial glia are investigated in vivo using the neuroepithelial markers nestin and vimentin and the gliogenic markers GLAST, BLBP, 3CB2, and glial fibrillary acidic protein (GFAP). This has revealed heterogeneity among nestin/vimentin-positive precursor cells and suggests a lineage progression from neuroepithelial cell through to astrocyte in the developing spinal cord. A population of self-renewing radial cells, distinct from an earlier pseudo-stratified neuroepithelium, that resemble radial glial cells in morphology but do not express GLAST, BLBP, or 3CB2, is revealed. These radial cells arise directly from the spinal cord neuroepithelium and are probably the progenitors of neurons and the earliest appearing radial glial cells. GLAST/BLBP-positive radial glia first appear in the ventral cord at E14, and these cells gradually transform through one or more intermediate stages into differentiated astrocytes. Few if any neurons appear to be derived from radial glial cells, which are instead the major sources of astrocytes in the spinal cord. Evidence for the nonradial glial cell origins of some white matter astrocytes is also presented.     

Inhibitory effect of calcium channel blockers on proliferation of human glioma cells in vitro

The effects of 2 specific calcium channel blockers, verapamil and nimodipine, on the proliferation of human glioma tumour cells were investigated in vitro. Tumour tissues for primary cell cultures were obtained bioptically from 3 patients with the histopathological diagnosis of glioblastoma. The [3H]-thymidine incorporation into glioma tumour cells DNA was used as a sensitive index of the cell proliferation. It was found that verapamil (10(-4)-10(-5) M) and nimodipine (10(-4)-10(-6) M) significantly inhibited the [3H]-thymidine uptake in a dose-related manner. The inhibitory effect of both calcium channel antagonists was reversed by simultaneous addition of calcium chloride (5 x 10(-3) M). These results indicate that verapamil and nimodipine may exert an antiproliferative effect on glioma cells growth acting through a blockade of specific voltage-dependent calcium channels.     

PiB对胶质瘤细胞增殖与侵袭能力的影响

目的探讨PIN1抑制剂Pi B对U87胶质瘤细胞系增殖、迁移和侵袭能力的影响。方法人胶质瘤细胞系U87常规培养,取对数生长期细胞进行试验,以1.0μmol/L Pi B处理U87细胞48 h为实验组,未经任何处理的U87细胞作为对照组。RT-PCR和Western blotting检测PIN1基因的m RNA和蛋白表达。免疫荧光检测阳性细胞数。Transwell实验检测细胞迁移和侵袭能力的改变。MTT比色法检测Pi B对细胞增殖的抑制作用。结果与对照组相比,实验组细胞PIN1基因的m RNA和蛋白表达水平明显下调,PIN1阳性细胞数明显减少,细胞抑制率明显,且与药物剂量和作用时间成相关性,细胞迁移和侵袭能力下降,差异有统计学意义（P〈0.05）。结论 Pi B可靶向抑制PIN1基因的m RNA和蛋白水平表达,进而抑制胶质瘤细胞增殖、迁移和侵袭能力。     

星形胶质细胞诱导成年大鼠骨髓基质细胞分化前后的电生理功能鉴定

目的 探讨骨髓基质细胞向神经元方向分化后是否具备神经元的电生理功能。方法 应用膜片钳技术,釆用全细胞记录方式.对由星形胶质细胞诱导的分化前、分化3d、分化7d的成年大鼠骨髓基质细胞进行电生理功能测定。结果分化前后的骨髓基质细胞未记录到内向Na~+电流,但成功记录到了静息膜电位,分別为:(-12.71±3.25)mV(n=7)、(-26.29±10.34)mV(n=7)、(-45.0±8.46)mV(n=6);刺激脉冲为40 mV时三组的外向延迟整流K~+电流分別为:(0.31±0.17)nA(n=7)、(1.34±0.59)nA(n=8)、(1.99±0.97)nA(n=7);刺激脉冲为-40 mV时的内向整流K~+电流为:(79±58)pA(n=7)、(260±150)pA(n=8)、(420±120)pA(n=7),伴随着分化时间的逐渐延长,两种K~+电流及膜电位逐渐增高。结论(1)骨髓基质细胞表达弱的外向延迟整流K~+电流及内向整流K~+电流可能是其特征性的电生理指标。(2)骨髓基质细胞经过星形胶质细胞的诱导能够向功能性神经元方向分化。     

Culture of purified rat astrocytes in serum-free medium supplemented with mitogen

We have obtained a highly purified astrocyte population in cultures originating from neonatal (2–5 days) rat cerebrum by use of the selection process provided by a serum-free chemically defined medium (DM). The addition of a glial growth factor isolated from bovine pituitary glands to DM induced in these astrocyte cultures both a stimulation of astrocytic proliferation and a morphological transformation of the astrocytes from flat fibroblastic form to multipolar stellate form.     

RNA干扰Bmi-1对胶质瘤细胞增殖的影响

目的 初步探讨Bmi-1基因对胶质瘤细胞增殖状况的影响.方法 采用RNA干扰技术沉默U251胶质瘤细胞中Bmi-1基因,RT-PCR检测干扰效果,CCK8观察U251细胞的增殖状况.结果 RNA干扰Bmi-1后,Bmi-1基因表达降低,U251细胞增殖减慢.结论 Bmi-1基因可以促进胶质瘤细胞的增殖,有可能促进了...     

Agonist-mediated endocytosis of rat somatostatin receptor subtype 3 involves beta-arrestin and clathrin coated vesicles

Agonist-induced endocytosis of somatostatin receptors determines subsequent cellular responsiveness to peptide agonist and influences somatostatin receptor scintigraphy, a technique to image various tumours. We examined the internalization of sst3HSV, an epitope-tagged type 3 somatostatin receptor, in transfected rat neuroendocrine insulinoma cells. Stimulation of these cells with somatostatin induced trafficking of coexpressed enhanced green fluorescence protein/beta-arrestin1 fusion protein and sst3HSV to colocalize in the same endocytic vesicles. Coexpression of a dominant negative mutant of the arrestin fusion protein with the receptor blocked the internalization of sst3HSV. Stimulation with somatostatin also induced the transient translocation of alpha-adaptin, a component of the adaptor protein complex 2, to the plasma membrane. alpha-adaptin and clathrin colocalized with the receptor. By electron microscopy, we observed internalized sst3 in clathrin coated pits, endosomes and at the limiting membrane of multivesicular bodies, a location typical for receptors being recycled. Concordantly, we observed sst3HSV colocalized with Rab11 in a perinuclear compartment which is likely to correspond to the pericentriolar recycling endosome. Thus, agonist-induced endocytosis of sst3 depends on its interaction with beta-arrestin, involves the adaptor protein complex 2 and proceeds via clathrin coated vesicles to the recycling compartment.