谷氨酰胺对大鼠海马脑片谷氨酸递质释放的影响

在以前的工作中我们观察到 ,饲料中补充谷氨酰胺 (Ｇｌｎ)可使大鼠脑组织中Ｇｌｎ和谷氨酸 (Ｇｌｕ)含量升高 ,并引起一系列代谢和功能的改变。当脑组织处于丰富的Ｇｌｎ环境中时 ,Ｇｌｕ等兴奋性氨基酸的释放是否会受到影响呢 ?由于条件所限 ,在整体无法观察这一过程 ,但离体脑片为我们提供了一个较为理想的研究方法。本实验通过对离体海马脑片进行孵育 ,观察Ｇｌｎ对Ｇｌｕ递质释放的影响 ,从而进一步探讨Ｇｌｎ的中枢作用机制。1　材料与方法(1)人工脑脊液 (ＡＣＳＦ)的配制　所用标准ＡＣＳＦ的配方为 (ｍｍｏｌ/Ｌ) :ＮａＣｌ 12 4,Ｋ…     

胆碱能神经对人餐后神经降压素释放的影响

本文比较了6名健康成人进食、餐前肌注阿托品以及单纯咀嚼食物后的血浆神经降压素样免疫活性物质(NTLI)水平的变化,以探讨胆碱能神经对神经降压素释放的影响。用放射免疫测定法分别测定NTLI和胰多肽(PP)的含量,以便同时比较两者释放的状态。6人的基础血浆NTLI和PP的水平平均分别为15.7±2.4和16.6±9 7pmol/L。进食后,血浆NTLI和PP水平均显著增高,并呈双相反应。第一个血浆NTLI高峰平均为60.7±13.2pmol/L,出现于餐后的20min。餐后90min,又出现另一个高峰,其平均水平为58.8±8.2pmol/L。在进食前肌注阿托品1mg,餐后的第一个血浆NTLI高峰消失,而第二个高峰仍存在。单纯咀嚼食物后,血浆PP水平明显增高,而对NTLI的释放无刺激作用。本文结果提示,餐后早期的神经降压素释放的调节是由非迷走胆碱能神经参与的,而后期的释放不受胆碱能神经的影响。     

蝎毒对癫痫敏感性和海马GFAP释放的影响

目的和方法 :本工作用海人酸癫痫模型 ,通过对癫痫大鼠蝎毒治疗后行为变化及脑内胶质原纤维酸性蛋白(GFAP)免疫反应活性的检测 ,对蝎毒抗癫痫反复发作的相关脑区及其机制做以初步探讨。结果 :癫痫大鼠蝎毒治疗三周后 ,能明显减少癫痫发作的例数 ,减轻癫痫发作的程度 ,使发作的潜伏期延长 (P <0 .0 5 )。免疫细胞化学的实验显示 ,蝎毒抗癫痫反复发作的相关脑区是海马。 8例蝎毒治疗的大鼠与实验对照组相比 ,有 6例背侧海马GFAP免疫染色明显减轻 ,未见星形胶质细胞增生 ;CA1区无明显神经元缺失 ;而且与空白对照组相比无显著差异。结论 :癫痫大鼠蝎毒治疗三周后 ,能明显减轻癫痫发作的行为 ,抑制海马星形胶质细胞的增生肥大 ,减轻海马神经元受损的程度。蝎毒抑制海马星形胶质细胞增生很可能是蝎毒抗癫痫反复发作的重要机制之一。     

GABA对大鼠下丘脑正中隆起LHRH释放调节的研究

本研究应用大鼠下丘脑正中隆起(ME),观察 γ-氨基丁酸(GABA)和去甲肾上腺素(NA)对下丘脑促黄体生成激素释放激素(LHRH)神经元末梢分泌作用的影响。结果发现:GABA(10~(-6)mol/L)可显著促进 ME 的 LHRH 和 NA 的释放,即 LHRH 释放量由27.3±2.5pg/100ul 增加至150.4±27.9pg/100μl;NA 释放量由50.9±4.2pg/100μl 增加至105.5±19.1pg/100ul,两者与对照组相比有显著差异(P<0.01)。GABA 这些作用可被受体拮抗剂荷包牡丹碱(Bicuculline)所翻转。当荷包牡丹碱和 GABA(10~(-6)mol/L)同时存在于 ME 的培灌液中,LHRH 的分泌量下降为18.2±1.9pg/100μl,而 NA 分泌量下降为43.9±3.4pg/100μl。在内源性 NA 被利血平耗竭时,LHRH 的释放量仅增加26.5%,而 GABA 能使正常大鼠 LHRH 释放量增加451.9%。本研究提示:GABA 可促进下丘脑 ME 释放 LHRH,这一作用可能通过 NA 中介。     

EFFECT OF CHOLINE ON THE RATES OF SYNTHESIS and OF RELEASE OF ACETYLCHOLINE IN THE ELECTRIC ORGAN OF TORPEDO

Abstract— Slices of electric organ of Torpedo marmorata were chopped and incubated in a saline-urea-sucrose medium. This preparation of minced tissue exhibited a relative enrichment in ACh and nerve endings, which was attributed to a loss of electroplaque cytoplasm. Electron microscopic controls showed nerve endings of normal morphology, some of them forming 'chaplets' separated from electro-plaques. Miniature endplate potentials were recorded on sealed fragments also present in this preparation. ACh levels remained unchanged during incubation periods as long as 19 h. The time course of the incorporation of [1-¹⁴C]acetate of [2-¹⁴C]pyruvate into ACh pools was studied. These incorporations were similarly affected by the choline added to the medium. In the presence of increasing choline concentrations (up to 10^-4 m ), the incorporation of [¹⁴C]acetate or [¹⁴C]pyruvate into ACh increased. They both diminished when choline was added above 10^-4M. The ACh content of the tissue was not affected by added choline. From the constancy of ACh levels in the presence of various choline concentrations and from the steady state of our preparation, we can conclude that the release of transmitter varied in parallel to the incorporation rate of the precursor of the acetyl moiety of ACh. This fact was also found using the efflux of [¹⁴C]acetate as an evaluation of ACh release. The values of release calculated by this method were in good agreement with those determined from the incorporations of acetate and pyruvate into ACh. It is suggested that the primary action of choline is on its high affinity carrier system. This triggers a secondary action on the ACh release mechanisms.     

经遗传修饰生物体的研究进展及其释放后对环境的影响

８０年代以来,以基因工程为代表的生物技术突飞猛进。转移不同性状的转基因作物在美国被批准进入大田试验的有４０个以上的作物,包括小麦、玉米和水稻等４种谷类粮食作物,主要的纤维作物棉花,蔬菜种类１０种以上,水果９种,其它还有油料作物,牧草和花卉等。到１９９６年６月已被批准进入市场的已有１８种,还有一批有待批准商业化。今年２月,美国农业部已第一次批准一种喂饲其它螨的转基因螨进入大田试验。第一个转基因线虫也正在申请向环境释放。已至少有２５个发展中国家,１０个以上作物转基因成功,ＧＭＯｓ作大田释放的总数在１６０次以上。基因工程能带来巨大的经济效益和社会效益。但是有不少数量的科学家或如“有关科学家联盟”等一些非政府组织指出基因工程的产物向环境释放会可能带来生态或环境危险。发达国家中,美国与欧洲国家的政府对ＧＭＯｓ批准释放的态度也是一样的,后者要比前者慎重得多。最近丹麦科学家已证实转基因油菜中的抗除草剂基因已经转入杂草中;由美国一种子公司开发的转基因大豆被证实对人体过敏而其产品决定不向市场投放。要有充分的科学实验,自然科学家与社会科学家相结合,对经遗传修饰生物体可能带来巨大经济效益和造成环境或生态危机进行充分的评估。在这基础上作出权衡,供政府决策者能作出正确的决策。这不仅在中国而是在全世界范围内已到了一个关键时刻。因此,生物安全问题是每次《生物多样性公约》缔约国会议的主要讨论议题。     

ULTRASTRUCTURE OF THE NACREOUS LEPTOIDS (SIEVE ELEMENTS) IN THE POLYTRICHACEOUS MOSS ATRICHUM UNDULATUM

The physiological phloem equivalents, leptoids, of the polytrichaceous moss Atrichum undulatum appear to be similar to the nacreous sieve elements that occur in many higher plants. These leptoids are elongated cells with nacreous thickenings on their radial and tangential walls. Their oblique end walls, which lack such thickenings, are traversed by numerous pores through which the plasmalemma, endoplasmic reticulum, and cytoplasm are continuous between adjacent leptoids of a longitudinal file. These end walls closely resemble the simple sieve areas of the sieve elements found in Polypodium vulgare. The leptoid sieve pores have a median expanded area and frequently are occluded by small amorphous protein plugs at each end. Also, callose was observed as electron-luscent areas both on the faces of the end walls and as a thin cylinder surrounding the lateral area of each pore. Amorphous and granular cytoplasmic contents of the leptoids appear to be morphologically similar to the slime (P-protein) found in the sieve-tube elements of many angiosperms. Differentiating leptoids are characterized by the formation of numerous membrane-bound protein bodies in close association with polysomes and endoplasmic reticulum. As the leptoid matures, the contents of the protein bodies become dispersed in the cytoplasm. Ultrastructurally and ontogenetically the leptoids in the gametophores of A. undulatum appear almost identical to the sieve elements of P. vulgare and therefore should be considered sieve elements rather than phloem-like equivalents.     

THE EFFECT OF SULFHYDRYL REAGENTS ON THE TITYUSTOXIN-INDUCED ACETYLCHOLINE RELEASE IN RAT BRAIN SLICES1

Abstract— Pre-treatment of rat brain slices with organic mercurials prevents the increased acetylcholine release induced by tityustoxin. This inhibition is reversed by dithiothreitol. N-Ethylmaleimide blocks the tityustoxin effect irreversibly. Simultaneous incubation with mercurials and toxin reveals a competition of both ligands for a membrane sulfhydryl group apparently required for tityustoxin activity.     

白细胞介素—8扩血管效应与内皮舒张因子的关系

为探讨内皮舒张因子在白细胞介素-8(IL-8)扩血管效应中的作用,本实验在大鼠离体主动脉条上,观察IL-8对血管反应性及血管组织cGMP含量的影响。实验发现,IL-8显著地扩张离体血管,其作用在去内皮后明显减弱。IL-8还能显著地提高离体血管组织cGMP含量,一氧化氮合成抑制剂L-NNA可阻断这一作用,一氧化氮前体L-精氨酸可逆转L-NNA的效应。结果表明IL-8可以通过促进血管内皮细胞释放一氧化氮而扩张血管。     

IN VITRO EXPERIMENTS ON THE METABOLISM, ACCUMULATION AND RELEASE OF 5-HT IN THE NERVOUS SYSTEM OF THE SNAIL HELIX POMATIA

Abstract— The accumulation, metabolism and stimulated-induced release of 5-HT in the nervous system of the snail was studied. When nervous tissue was incubated at 24°C in a medium containing [¹⁴C]5-HT or [³H]tryptophan, tissue: medium ratios of about 25:1 and 4:1 respectively were obtained after 45 min incubation. The process responsible for [¹⁴C]5-HT accumulation showed properties of an active transport system: it was temperature sensitive and was greatly inhibited by dinitrophenol and ouabain. Furthermore, the accumulation process was inhibited by imipramine and desipramine. Of a number of analogues of indole, N-acetyl-5-HT and 5-hydroxytryptophan were the most potent in the inhibition of the accumulation of [¹⁴C]5-HT. The presence of a large molar excess of amino acids had little effect. A small amount (less than 14 per cent) of the accumulated [¹⁴C]5-HT was metabolized to form 5-hydroxyindole acetic acid, even after long periods (2 h) of incubation. The accumulated [³H]tryptophan was metabolized to form 5-hydroxytryptophan and 5-HT; the content of formed [³H]5-HT increased with incubation time whilst the [³H]5-hydroxytryptophan remained more or less constant. The presence of p-chlorophenylalanine in the incubation medium did not interfere with the accumulation of [³H]tryptophan, though it inhibited the formation of [³H]5-hydroxytryptophan and to a greater extent [³H]5-HT. A rapid efflux of the accumulated [¹⁴C]5-HT from snail nervous tissue was observed on electrical stimulation. Slower release resulted when the Ca²⁺ ion content of the incubation medium was replaced by Mg²⁺ ions. There is also a slight efflux of radioactive substances following electrical stimulation in tissues previously incubated in [³H]tryptophan. Most of this radioactivity was attributed to the formed [³H]5-HT. The data support the idea that 5-HT is a transmitter-substance in the snail Helix pomatia, and that re-uptake of the substance is a method of inactivating the released amine.     

EFFECT OF DENERVATION AND OF AXOPLASMIC TRANSPORT BLOCKAGE ON THE IN VITRO RELEASE OF MUSCLE ENDPLATE ACETYLCHOLINESTERASE

Abstract— Cat geniohyoid muscle samples containing endplate regions, when incubated in vitro at 37°C in phosphate buffer (pH 73, release acetylcholinesterase (AChE; EC 3.1.1.7) to the bathing medium. By treating the muscle samples with collagenase (EC 3.4.4.19), it was confirmed that most of the AChE released came from the endplates. Enzyme liberation was studied 10 days after either local injection of 10mM-cokhicine into the hypoglossal nerve or following nerve transection. Results showed that the rate of release is increased by denervation, but is not affected by axoplasmic transport blockage. It is postulated that the cellular contact between nerve and muscle—altered by denervation but not by interruption of axoplasmic transport—is an essential factor in maintaining the localization of end-plate AChE within the synaptic cleft substance. This does not invalidate the possible participation of ACh and muscle activity in such enzyme localization.     

泥鳅精子和卵子结构及受精过程的细胞学观察

研究旨在探讨泥鳅精子受精时限及为其人工繁殖提供基础资料。采用光镜、电镜技术对泥鳅（Misgurnus anguillicaudatus）精子、卵子和不同时间段的受精卵进行了观察。结果显示:泥鳅精子头部无顶体,主要为核占据,核凹窝较浅,中段具不对称的袖套,尾部轴丝为9+2结构,无侧鳍。卵子动物极卵膜仅有一受精孔,受精孔为深凹陷、短孔道型。在20-21℃水温条件下,授精后3s,精子开始穿过精孔管或已经进入卵子;授精后5-8s,形成精子星光;授精后70s,卵子处于第二次减数分裂后期;授精后6-8min,第二极体形成,等待排出;授精后20-25min,雌雄原核融合;授精后25-30min,受精卵进入第一次有丝分裂中期;授精后40-45min,第一次有丝分裂结束,二细胞形成。研究表明:成熟卵子精孔管内口径（2.2860.364）m,而精子头部直径与其接近,单精受精;入水后150s内可受精。     

池塘内循环流水养殖模式对养殖塘上覆水-沉积物-间隙水磷时空分布特征及释放通量的影响

为了揭示池塘内循环流水养殖模式(Inner-circulation Pond Aquaculture, IPA)上覆水-沉积物-间隙水不同磷形态时空分布特征,探讨沉积物-水界面磷的释放通量及其主要影响因素,在IPA一条水槽前后端设置6个采样点,共设置4条,同时对常规传统池塘(Usual Pond Aquaculture, UPA)设置5个采样点,采用SMT(磷形态标准测试程序)法测量沉积物中磷的形态组成,对上覆水-沉积物-间隙水磷时空分布特征进行了分析,统计了磷释放通量及主要影响环境因子的关系。结果表明:(1)从整体上, IPA上覆水及间隙水中不同形态磷含量低于UPA,且IPA水体磷空间分布差异较大,水槽后端沉积物向上覆水释放,水槽前端则表现为上覆水向沉积物汇集;(2)在养殖中后期,空间上, IPA水槽后端沉积物不同磷形态随着距离增加逐渐降低,且均低于UPA;时间上,2种模式TP、IP、OP和Fe/Al-P随着养殖的进行而显著增加, Ca-P呈先降低后增加的趋势;(3)UPA基本表现为沉积物对磷的吸收,而IPA磷释放通量时空差异较大,养殖初期,水槽前端表现对磷的吸收,水槽后端10 m内...     

波叶仙鹤藓的孢子培养及发育生物学研究

首次成功地进行了人工条件下波叶仙鹤藓(Atrichum undulatum(Hedw.)P.Beauv)单细胞孢子的培养,并详细研究、拍摄了其植物体(配子体)形态发育的全过程。孢子无后熟或体眠期,3-4天即可萌发,萌发率可达95％以上;培养10天左右绿丝体系统、轴丝体系统及假根开始分化,约40天开始出现芽体原基,50天芽体陆续形成,80天左右植物体完成营养生长,开始性器发育。初生假根发育不良,基原细胞不分裂,由绿丝体产生轴丝体的方式复杂,轴丝体细胞分裂面有球形和斜向、横向三种,芽原基分化时,首先在轴丝体上产生光合能力很强的细胞群,其基部产生芽原基,芽原基的分化成功率仅有50％左右,芽体形成后,原丝体系统多枯萎或特化为假根。并就波叶仙鹤藓的形态发育、生理生态、生殖和进化等方面也进行了理论探讨。     

聚皂凝胶对蛋白分子的吸附与释放

以牛血清白蛋白为对象,研究了丙烯酸－丙烯酰胺型９ＰＢｕＡＭＡ）和疏水改性的四乙烯五胺－环（ＨＰＴＥ）聚合物凝胶对蛋白质的及附与释放过程。在吸附过程中,当溶液ＰＨ值在牛血清白蛋白电点（４．７）附近时,凝胶蛋白抽的吸附值最大;而在释放过程中,ＰＨ＝７的释放率远大于其它ＰＨ值时的释放率。实验表明凝胶结构对蛋白质吸附与释放有较大影响。未疏水改性的凝胶与疏水改性的凝胶相比,前 的释放速率约为后者的２倍。结果     

睾酮对日本鳗鲡离体下丘脑-脑垂体复合物GtH合成与分泌的影响

用离体孵育的方法研究了睾酮（T）对日本鳗鲡（Anguilla japonica)完整的正丘脑-脑垂体复合物（hypothalamus-pituiary complex,HPC)、分离的下丘脑（hypothalamus,H)加脑垂体（pituitary,P)以及单独的脑垂体（pituitary,P)促性腺激素（GtH)合成与释放的影响,在不加T的孵育液中孵育,HPC组的孵育液及其脑垂体中的GtH含量最高,H P组次之,而P组最低,表明下丘脑通过GnRH直接刺激脑垂体GtH的合成与释放,在加入T的孵育液中孵育,P组的孵育液及脑垂体中的GtH含量显著增加,并且和孵育液中的T呈剂量依存的正反馈作用,当T和H与P一起孵育时,低浓度的T（0.1和1μmol/L)刺激HPC组和H P组的GtH释放,呈现正反馈作用,而高浓度的T（10μmol/L)则抑制HPC组和H P组的GtH释放,表现负反馈作用。这些结果直接证明日本鳗鲡下丘脑对脑垂体GtH分泌的调控以及性类固醇激素（如雄鳗的睾酮）对脑垂体GtH分泌的反馈作用。     

非热微波和方位对水迷宫大鼠空间认知的影响

描述了四组大鼠六个训练期从上释放点寻找圆形水迷宫（Ｍｏｒｒｉｓ）固定没水平台的动物行为实验,四组动物为,脉冲微波组（２４５０,ＭＨＺ,调制脉宽２μｓ,每秒５００脉冲,空间平均功率密度为２ｍＷ／ｃｍ＾２,平均整体特异吸收率ＳＡＲ,１．２ｗ／ｋｇ）,连续微波组（２４５０ＭＨＺ,无调制。空间平均功率宴席和ＳＡＲ同于脉冲微波组）,Ｓｈａｍ辐射组以及笼养对照组。以平均逃逸时间和速度为测量,考查它们的空间记忆