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1.
Lipoprotein uptake by neuronal growth cones in vitro 总被引：21，自引：0，他引：21
Macrophages that rapidly enter injured peripheral nerve synthesize and secrete large quantities of apolipoprotein E. This protein may be involved in the redistribution of lipid, including cholesterol released during degeneration, to the regenerating axons. To test this postulate, apolipoprotein E-associated lipid particles released from segments of injured rat sciatic nerve and apolipoprotein E-containing lipoproteins from plasma were used to determine whether sprouting neurites, specifically their growth cones, possessed lipoprotein receptors. Pheochromocytoma (PC12) cells, which can be stimulated to produce neurites in vitro, were used as a model system. Apolipoprotein E-containing lipid particles and lipoproteins, which had been labeled with fluorescent dye, were internalized by the neurites and their growth cones; the unmetabolized dye appeared to be localized to the lysosomes. The rapid rate of accumulation in the growth cones precludes the possibility of orthograde transport of the fluorescent particles from the PC12 cell bodies. Thus, receptor-mediated lipoprotein uptake is performed by the apolipoprotein B,E(LDL) (low density lipoprotein) receptors, and in the regenerating peripheral nerve apolipoprotein E may deliver lipids to the neurites and their growth cones for membrane biosynthesis. 相似文献
2.
Evoked release of norepinephrine and serotonin from brain slices: inhibitoon by lithium 总被引：1，自引：0，他引：1
Slices of mammalian brain accumulate H(3)-norepinephrine and H(3)-serotonin when incubated in a physiologic medium containing these tritiated monoamines. When these tissues are subjected to mild electrical stimulation of short duration, which is associated with depolarization of nerve membranes, a striking increase in the rate of efflux of the exogenous labeled monoamines occurs. Stimulation-induced release of both labeled monoamines is diminished by the presence of lithium ions in the perfusing medium; related monovalent cations had no such effect. Evoked release from slices of brain from animals treated intraperitoneally with lithium chloride for 3 days was also reduced. 相似文献
3.
鸡腔上囊传出神经元的分布——用CB—HRP法研究 总被引：6，自引：0，他引：6
将CB—HRP注入鸡腔上囊壁内,支配腔上囊的神经元被标记。支配腔上囊的长轴突型交感节前神经元在胸7—腰荐3(简称T_7—LS_3)髓节的Terni氏柱内,主要位于LS_1—LS_2髓节。在LS_8—LS_(11)髓节中央管背侧和背外侧区有大量标记细胞,主要集中于LS_8髓节,这些标记细胞是支配腔上囊的副交感节前神经元,其轴突大部分行经同侧盆神经到达腔上囊,少数行经对侧的盆神经到达腔上囊。腔上囊的交感节后神经元位于T_6—L_(13)交感干神经节和肾上腺神经节,交感干的标记细胞集中位于LS_9—LS_(11)和LS_2—LS_3。副交感节后神经元位于盆神经和泄殖腔神经节内。在肠神经内有大量的标记细胞。 相似文献
4.
Extracts of tissue fluids from a patient with subacute necrotizing encephalomyelopathy inhibit thiamine pyrophosphate-adenosine triphosphate phosphotransferase of rat brain. Brain tissue from the patient, in contrast to normal brain tissue, contained essentially no thiamine triphosphate, although thiamine and its other phosphate esters were present in normal concentrations. These findings suggest a relation between this disease and thiamine triphosphate. 相似文献
5.
用跨神经节技术追踪了鸡桡神经和腺胃初级传入向楔外核和孤束核的投射。将ＣＢ－ＨＲＰ分别注入鸡一侧桡神经和腺胃腹侧壁。结果表明，桡神经初级传入纤维向楔外核几乎全长都有投射，以闩前０．３２～０．７２ｍｍ靠近迷走神经髓内根丝腹侧的标记终末最为密集；在孤束内侧核内也有一定量的投射；腺胃初级传入纤维经迷走神经进入脑干，丰富地投射于孤束核。标记终末密集区位于闩前０．８０～１．６０ｍｍ范围的孤束内侧核，在楔外核也有较为丰富的投射，浓密的标记终末出现在闩前０．４０～０．８０ｍｍ范围的该核内。另外，桡神经和腺胃初级传入纤维在三叉神经脊束内也见有少量投射。 相似文献
6.
Renal adenyl cyclase: anatomically separate sites for parathyroid hormone and vasopressin 总被引：45，自引：0，他引：45
Adenyl cyclase from plasma membrane fractions of rat renal cortex or medulla was assayed by measuring conversion of adenosine triphosphate labeled at the alpha-phosphate with (32)P to cyclic 3',5'-adenosine monophosphate labeled with 32P. Parathyroid hormone activated the enzyme primarily in cortex; vasopressin acted primarily in medulla. These experiments support the conclusion that cyclic adenosine monophosphate mediates the action of parathyroid hormone on the kidney and show that parathyroid hormone and vasopressin stimulate adenyl cyclase at anatomically separable areas within the kidney. 相似文献
7.
Human red blood cell membranes were labeled from within the lipid bilayer by the apolar photosensitive reagent, 5-[125I]iodonaphthyl-1-azide. Glycophorin, the major sialoglycoprotein of the red cell membrane, was purified by two different methods; it contained approximately half of the total label incorporated into membrane proteins. The label was confined to the trypsin-insoluble peptide of glycophorin that includes a sequence of 20, mainly apolar, amino acids. These findings provide direct evidence that the labeled segment resides within the membrane in direct contact with the lipid bilayer, and support the suggestion that glycophorin spans the bilayer through its hydrophobic domain. 相似文献
8.
Response to ethanol reduced by past thiamine deficiency 总被引：1，自引：0，他引：1
P R Martin E Majchrowicz E Tamborska C Marietta A B Mukherjee M J Eckardt 《Science (New York, N.Y.)》1985,227(4692):1365-1368
Ethanol-induced intoxication and hypothermia were studied in rats approximately 7 months after severe thiamine deficiency, when treated rats appeared to have recovered their physical health. Previously induced thiamine deficiency without prior ethanol exposure significantly decreased the area under the curve plotted for the concentration of ethanol in blood and also decreased behavioral impairment and hypothermia due to ethanol exposure. Pathophysiologic changes resulting from thiamine deficiency may contribute to both the pharmacodynamic and pharmacokinetic tolerance to ethanol in chronic alcoholics. 相似文献
9.
Simian sarcoma virus--transformed cells secrete a mitogen identical to platelet-derived growth factor 总被引：28，自引：0，他引：28
Normal rat kidney (NRK) cells transformed by simian sarcoma virus (SSV) release into the culture medium a biologically active mitogen with properties identical to those of human platelet-derived growth factor (PDGF). Like PDGF, the growth factor derived from SSV-NRK cells was shown to be stable to heat and sensitive to reducing agents. It was capable of inhibiting binding of labeled PDGF to the receptor on human fibroblasts. It also stimulated the phosphorylation of the same membrane protein (185 kilodaltons) in isolated plasma membranes from human fibroblasts. Immunoprecipitation of metabolically labeled proteins released by SSV-NRK cells showed that a 34-kilodalton protein was specifically precipitated by antiserum to PDGF. Upon reduction, this protein had a molecular size of 17 kilodaltons. PDGF has been shown to consist of two 14- to 18-kilodalton proteins linked by disulfide bonds. 相似文献
10.
11.
Radioautography of the optic tectum of the goldfish, performed after injection of [(3)H]proline into the contralateral eye, effectively resolves several distinct layers of retinal synapses. Silver grains are found unilaterally over nerve tracts containing efferent fibers from the tectum, a result that suggests intercellular migration of labeled molecules. The low background and high specific grain density obtained with [(3)H]proline radioautography indicate the usefulness of this technique for the elucidation of neuroanatomical connections in the visual system. 相似文献
12.
Perineural epithelium: a new concept of its role in the integrity of the peripheral nervous system 总被引：3，自引：0，他引：3
A multilayered, squamous-celled epithelial cell membrane covering the individual nerve fasciculi of the entire peripheral nervous system ( both voluntary and autonomic) including the sensory and motor end organs has been demonstrated in various species of animals, including man. This membrane is the direct continuation of the pia-arachnoid mater from the central nervous system.Functional significance of this membrane, especially as a diffusion barrier and as a protector of the peripheral nervous system, is briefly discussed. 相似文献
13.
Novel pharmacology of substance K-binding sites: a third type of tachykinin receptor 总被引：18，自引：0，他引：18
S H Buck E Burcher C W Shults W Lovenberg T L O'Donohue 《Science (New York, N.Y.)》1984,226(4677):987-989
The tachykinins are a family of peptides with the carboxyl terminal amino acid sequence Phe-X-Gly-Leu-Met-NH2. Three major mammalian tachykinins have been identified--substance K, neuromedin K, and substance P--but only two tachykinin receptors have been postulated. Three tachykinins were labeled with radioiodinated Bolton-Hunter reagent and their binding characteristics were determined in crude membrane suspensions from several tissues. In cerebral cortex labeled eledoisin exhibited high-affinity binding that was inhibited by tachykinins in a manner indicating a definitive SP-E receptor site. In gastrointestinal smooth muscle and bladder, high-affinity binding of labeled substance P was inhibited in a pattern indicating a definitive SP-P site. In intestinal smooth muscle and bladder, however, labeled substance K and labeled eledoisin were both bound in a pattern indicating a preference for substance K itself. The results suggest the existence of three distinct types of tachykinin receptors: SP-P, SP-E, and SP-K. 相似文献
14.
本实验将ＣＢ—ＨＲＰ注入鸡一侧胸腺内，通过逆行和跨神经节追踪支配鸡胸腺的副交感节前神经元的位置。其结果如下：１．在延髓双侧迷背核内发现标记细胞，标记细胞出现在闩后０．８２～０．１０ｍｍ，和闩前１．５５～２．４６ｍｍ两个区域内，主要应于闩后的尾背侧大细胞亚核和尾腹侧中细胞亚核，闩前的前背侧中细胞亚核、前背侧小细胞亚核、前腹侧小细胞亚核。标记细胞大多为中小型的圆形、椭圆形和梭形细胞。２．双侧舌咽神经背运动核出现标记细胞。３．双侧舌咽神经腹运劝核出现标记细胞，际记细胞为中等多极神经元，树突明显，交织成网。４．在双侧疑后核，中间带和中介核内都出现少量标记细胞。研究证明：支配鸡胸腺的副交感节前神经元位于迷背核、舌咽神经背运动核、舌咽神经腹运动核，亦位于疑后核、中间带及中介核。一侧胸腺受双侧神经支配。 相似文献
15.
Guanosine triphosphatases of the Rab family are key regulators of membrane trafficking, with Rab11 playing a specific role in membrane recycling. We identified a mammalian protein, protrudin, that promoted neurite formation through interaction with the guanosine diphosphate (GDP)-bound form of Rab11. Phosphorylation of protrudin by extracellular signal-regulated kinase (ERK) in response to nerve growth factor promoted protrudin association with Rab11-GDP. Down-regulation of protrudin by RNA interference induced membrane extension in all directions and inhibited neurite formation. Thus, protrudin regulates Rab11-dependent membrane recycling to promote the directional membrane trafficking required for neurite formation. 相似文献
16.
Perineurium originates from fibroblasts: demonstration in vitro with a retroviral marker 总被引：6，自引：0，他引：6
A cellular sheath, the perineurium, forms a protective barrier around fascicles of nerve fibers throughout the peripheral nervous system. In a study to determine the cellular origin of perineurium, a culture system was used in which perineurium forms after purified populations of sensory neurons, Schwann cells, and fibroblasts are recombined. Before recombination, the Schwann cells or the fibroblasts were labeled by infection with a defective recombinant retrovirus whose gene product, beta-galactosidase, is histochemically detectable in the progeny of infected cells. Perineurial cells were labeled when fibroblasts had been infected but not when Schwann cells had been infected. Thus, perineurium arises from fibroblasts in vitro and, by implication, in vivo as well. 相似文献
17.
屠宰健康荷斯坦奶牛,制备乳腺组织冰冻切片,免疫荧光双重标记检测,比较单克隆和多克隆α5、β1亚基一抗的特异性(FITC标记二抗),用SMMHC多克隆一抗,TRITC标记二抗特异标识肌上皮细胞来辅助定位靶信号,Hoechst33258复染细胞核,在激光共聚焦显微镜下连续断层扫描并拍照。结果表明,借助对肌上皮细胞和细胞核染色定位清晰可见乳腺结构,α5、β1亚基主要分布在导管和腺泡腔上皮细胞膜、外围肌上皮细胞膜和间质中的成纤维细胞膜上,前者在面向腔和靠近基膜的细胞顶侧和基底侧表达均较强,后者仅在基底侧细胞膜上。对于具有极性分布的细胞膜抗原单克隆一抗定位更准确。α5、β1亚基定位在相同区域表明,α5β1异二聚体具有在导管和腺泡基底侧极性分布的表达特点,α5亚基在面向导管和腺泡腔的上皮细胞顶膜上表达,而β1亚基不表达或弱表达,显示该区域存在非α5β1异二聚体形式的α5亚基。 相似文献
18.
The crystal structure of thiamine pyrophosphate has been determined by a three-dimensional x-ray analysis. The conformation of the molecule in the crystalline state is determined by the formal charge distribution within the molecule which exists as a zwitterion with the negative pyrophosphate chain folded back over the positive, ring portion of the molecule. The oxygen atoms in the pyrophosphate group are in the staggered conformation when viewed along the phosphorus-phosphorus axis. Even though the pyrophosphate is present in this compound as the monoionized monoester, the configuration is the same as that present in the inorganic pyrophosphate ion. From a comparison of three different crystal structures containing the thiamine moiety and from studies with atomic models, it seems plausible that the basic molecular conformation observed in this crystal is maintained in the catalytically active molecule. Knowledge of the detailed crystal structure provides new insight into the biochemical mechanism of reactions catalyzed by thiamine pyrophosphate. 相似文献
19.
蛇毒突触前磷脂酶A2神经毒素(Snake presynaptic phospholipase A2 neurotoxins,SPANs)是蛇毒中毒性最大的成分之一,主要作用于脊椎动物神经-肌肉接头(Neuromuscular junction,NMJ)处,阻断神经递质乙酰胆碱的释放致使动物肌肉麻痹、呼吸衰竭直至死亡。SPANs与突触前膜特异性结合,水解膜磷脂生成溶血磷脂(Lysophospholipids,LysoPC)和脂肪酸(Fatty acids,FA),改变膜构象、膜通透性提高导致Ca2+大量内流至神经末梢、突触囊泡(Synaptic vesicles,SV)枯竭、线粒体功能障碍等。对蛇毒突触前磷脂酶A2神经毒素的受体分子及其引发的一系列胞内分子事件进行综述。 相似文献
20.
刘英 《甘肃农业大学学报》1995,30(3):210-213
本文用１４只１．０～２．５ｋｇ重的成年鸡研究嗉囊的副交感神经元定位。将ＨＲＰ注入嗉囊，动物存活２～４天后心室固定。取迷走神经远神经节、岩神经节和颈静脉神经节及延髓，制成５０μｍ厚的冰冻切片，用Ｍｅｓｕｌａｍ氏ＴＭＢ法反应呈色，明视野观察，结果如下：１．被标记的嗉囊副交感节前神经元出现于迷走神经背侧运动核和中间核内。嗉囊的标记细胞在迷走神经背侧运动核内的分布有局部定位关系。２。被标记的嗉囊感觉神经元出现于远神经节、岩神经节和颈静脉神经节内。 相似文献