Adrenal medulla grafts enhance recovery of striatal dopaminergic fibers

The drug, 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP), depletes striatal dopamine levels in primates and certain rodents, including mice, and produces parkinsonian-like symptoms in humans and nonhuman primates. To investigate the consequences of grafting adrenal medullary tissue into the brain of a rodent model of Parkinson's disease, a piece of adult mouse adrenal medulla was grafted unilaterally into mouse striatum 1 week after MPTP treatment. This MPTP treatment resulted in the virtual disappearance of tyrosine hydroxylase-immunoreactive fibers and severely depleted striatal dopamine levels. At 2, 4, and 6 weeks after grafting, dense tyrosine hydroxylase-immunoreactive fibers were observed in the grafted striatum, while only sparse fibers were seen in the contralateral striatum. In all cases, tyrosine hydroxylase-immunoreactive fibers appeared to be from the host rather than from the grafts, which survived poorly. These observations suggest that, in mice, adrenal medullary grafts exert a neurotrophic action in the host brain to enhance recovery of dopaminergic neurons. This effect may be relevant to the symptomatic recovery in Parkinson's disease patients who have received adrenal medullary grafts.     

Dopaminergic neurotoxicity of 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine in mice

1-Methyl-4-phenyl-1,2,5,6- tetrahydropyri dine ( MPTP ) is known to cause an irreversible destruction of the dopaminergic nigrostriatal pathway and symptoms of parkinsonism in humans and in monkeys. However, MPTP has been reported to act only minimally or not at all in several other animal species. When MPTP (30 milligrams per kilogram of body weight) was administered parenterally to mice, a decrease in concentrations of neostriatal dopamine and its metabolites, a decrease in the capacity of neostriatal synaptosomal preparations to accumulate [3H]dopamine, and a disappearance of nerve cells in the zona compacta of the substantia nigra were observed. In contrast, MPTP administration had no effect on neostriatal concentrations of serotonin and its metabolites. MPTP administration thus results in biochemical and histological changes in mice similar to those reported in humans and monkeys and similar to those seen in Parkinson's disease in humans. The mouse should prove to be a useful small animal with which to study the mode of action of MPTP .     

Reward-predictive cues enhance excitatory synaptic strength onto midbrain dopamine neurons

Using sensory information for the prediction of future events is essential for survival. Midbrain dopamine neurons are activated by environmental cues that predict rewards, but the cellular mechanisms that underlie this phenomenon remain elusive. We used in vivo voltammetry and in vitro patch-clamp electrophysiology to show that both dopamine release to reward predictive cues and enhanced synaptic strength onto dopamine neurons develop over the course of cue-reward learning. Increased synaptic strength was not observed after stable behavioral responding. Thus, enhanced synaptic strength onto dopamine neurons may act to facilitate the transformation of neutral environmental stimuli to salient reward-predictive cues.     

Differential effects of classical and atypical antipsychotic drugs on A9 and A10 dopamine neurons

Prolonged treatment with classical antipsychotic drugs decreased the number of spontaneously active dopamine neurons in both the substantia nigra (A9) and the ventral tegmental area (A10) of the rat brain. In contrast, treatment with atypical antipsychotic drugs selectively decreased the number of A10 dopamine neurons. Related drugs lacking antipsychotic efficacy failed to decrease dopamine activity. These findings suggest that the inability of atypical antipsychotic drugs to decrease A9 dopamine neuronal activity may be related to their lower potential for causing tardive dyskinesia and that the inactivation of A10 neurons may be involved in the delayed onset of therapeutic effects during treatment.     

Nerve growth factor attenuates neurotoxic effects of taxol on spinal cord-ganglion explants from fetal mice

Most neurons in organotypic cultures of dorsal root ganglia from 13-day-old fetal mice require high concentrations of nerve growth factor for survival during the first week after explanation. These nerve growth factor-enhanced sensory neurons mature and innervate the dorsal regions of attached spinal cord tissue even after the removal of exogenous growth factor after 4 days. In cultures exposed for 4 days to nerve growth factor and taxol (a plant alkaloid that promotes the assembly of microtubules) and returned to medium without growth factor, greater than 95 percent of the ganglionic neurons degenerated and the spinal cord tissues were reduced almost to monolayers. In contrast, when the recovery medium was supplemented with nerve growth factor, the ganglionic neurons and dorsal (but not ventral) cord tissue survived remarkably well. Dorsal cord neurons do not normally require an input from dorsal root ganglia for long-term maintenance in vitro, but during and after taxol exposure they become dependent for survival and recovery on the presence of neurite projections from nerve growth-factor-enhanced dorsal root ganglia.     

Role for excitatory amino acids in methamphetamine-induced nigrostriatal dopaminergic toxicity

The systemic administration of either methamphetamine or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to experimental animals produces degenerative changes in nigrostriatal dopaminergic neurons or their axon terminals. This study was conducted to determine if excitatory amino acids, which appear to be involved in various neurodegenerative disorders, might also contribute to the dopaminergic neurotoxicity produced in mice by either methamphetamine or MPTP. MK-801, phencyclidine, and ketamine, noncompetitive antagonists of one subtype of excitatory amino acid receptor, the N-methyl-D-aspartate receptor, provided substantial protection against neurotoxicity produced by methamphetamine but not that produced by MPTP. These findings indicate that excitatory amino acids play an important role in the nigrostriatal dopaminergic damage induced by methamphetamine.     

醋酸铅对体外培养大鼠大脑皮质神经细胞形态的影响

为了观察醋酸铅对神经细胞的形态学影响,通过建立体外培养大鼠大脑皮质神经细胞模型,应用不同浓度醋酸铅(0,50,100,200,400μmol/L)与神经细胞分别培养3、6、12、24 h,倒置相差显微镜观察细胞形态变化.结果显示,醋酸铅与神经细胞共同培养12~24 h,细胞密度降低,胞体变小,突起缩短;随醋酸铅浓度递增,细胞形态较对照组差异愈加显著(P<0.05).表明染铅浓度与神经细胞形态变化存在剂量效应与时间效应关系.     

啮齿类海马神经元的原代培养及方法改进

目的:通过对新生啮齿类海马神经元的分离和培养,尝试建立一个简单、稳定、高效的啮齿类海马神经元原代培养方法,为脊髓损伤的相关分子机制研究提供目的细胞。方法:取新生SD乳鼠的海马组织,通过低浓度胰酶消化制成细胞悬液、4h差速贴壁后使用无血清Neurobasal培养基培养,倒置显微镜观察细胞生长状态,免疫荧光对海马神经元相关微管蛋白-2(MAP2)行特异性染色,结合DAPI核染色鉴定神经元。结果:该方法培养的海马神经元生长状态良好,纯度较高。结论:采用低浓度胰酶消化,差速贴壁及无血清培养啮齿类海马神经元符合体外细胞实验要求,为进一步研究提供良好的目的细胞。     

Uniform inhibition of dopamine neurons in the ventral tegmental area by aversive stimuli

Dopamine neurons play a key role in reward-related behaviors. Reward coding theories predict that dopamine neurons will be inhibited by or will not respond to aversive stimuli. Paradoxically, between 3 and 49% of presumed dopamine neurons are excited by aversive stimuli. We found that, in the ventral tegmental area of anesthetized rats, the population of presumed dopamine neurons that are excited by aversive stimuli is actually not dopaminergic. The identified dopamine neurons were inhibited by the aversive stimulus. These findings suggest that dopamine neurons are specifically excited by reward and that a population of nondopamine neurons is excited by aversive stimuli.     

斑马鱼性腺组织的原代细胞培养技术的建立

[目的]建立斑马鱼卵巢和精巢组织的原代细胞培养技术,获得原代和传代培养细胞单层。[方法]采用组织块贴壁法进行斑马鱼卵巢和精巢组织的原代细胞培养,采用0.25%胰蛋白酶消化法进行传代培养。[结果]斑马鱼性腺组织的原代细胞培养条件为:最适培养基为DMEM/F12(p H 7.0~7.2),培养温度为24℃,在添加20 ng/m L表皮生长因子(EGF)、20 ng/m L碱性成纤维细胞生长因子(b FGF)、0.5 mmol/Lβ-巯基乙醇和15%胎牛血清时更有利于细胞的存活。其中,卵巢的组织块接种3~4 d后,上皮样细胞首先开始迁出,迁出的上皮样细胞生长5 d后,逐渐凋亡;此后,成纤维样细胞和另一种上皮样细胞开始大量迁出,10 d后可生长汇合成80%的原代细胞单层;可成功传代培养1次,但传代后的上皮样细胞不贴壁,很快死亡,而传代后的成纤维样细胞可贴壁生长,但基本不分裂,健康存活7 d后开始逐渐凋亡。精巢组织接种5 d后,上皮样细胞和成纤维样细胞同时开始迁出,培养16 d后逐渐凋亡,仅得到60%原代培养细胞单层。[结论]初步建立了斑马鱼性腺组织的原代细胞培养条件,并将卵巢组织块迁出的成纤维样细胞成功传代1次。     

Selectivity of the parkinsonian neurotoxin MPTP: toxic metabolite MPP+ binds to neuromelanin

Methylphenyltetrahydropyridine (MPTP) selectively destroys neuronal cell bodies in the melanin-containing substantia nigra of humans and other primates. We show that methylphenylpyridine (MPP+), an active metabolite of MPTP which is accumulated intraneuronally by the catecholamine uptake system, binds with high affinity to melanin and neuromelanin. MPP+ bound intracellularly to neuromelanin may be released gradually, resulting in subsequent damage to the neurons of the substantia nigra.     

Parietal lobe: from action organization to intention understanding

Inferior parietal lobule (IPL) neurons were studied when monkeys performed motor acts embedded in different actions and when they observed similar acts done by an experimenter. Most motor IPL neurons coding a specific act (e.g., grasping) showed markedly different activations when this act was part of different actions (e.g., for eating or for placing). Many motor IPL neurons also discharged during the observation of acts done by others. Most responded differentially when the same observed act was embedded in a specific action. These neurons fired during the observation of an act, before the beginning of the subsequent acts specifying the action. Thus, these neurons not only code the observed motor act but also allow the observer to understand the agent's intentions.     

Dopamine-accumulating retinal neurons revealed by in vitro fluorescence display a unique morphology

Dopamine is the principal catecholamine neurotransmitter in the vertebrate retina. The shape of retinal neurons that accumulate dopamine has been demonstrated in an in vitro preparation of cat retina. This was achieved by the discovery that the combined uptake of dopamine and the indoleaminergic transmitter analog 5,7-dihydroxytryptamine leads to an intense, catecholamine-like fluorescence in the cell bodies and processes of presumed dopaminergic amacrine cells in the living retina. This fluorescence served as an in vitro marker for these cells, and their detailed morphology was analyzed after intracellular injection of horseradish peroxidase under direct microscopic control. The horseradish peroxidase-filled cells show an unprecedented neuronal morphology: each cell gives rise to multiple, axon-like processes that arise from, and extend for millimeters beyond, the dendritic tree. The unique structure of this type of amacrine cell suggests a function for dopamine in long-range lateral interactions in the inner plexiform layer.     

Suppression of neurite elongation and growth cone motility by electrical activity

Electrical activity may regulate a number of neuronal functions in addition to its role in transmitting signals along nerve cells. The hypothesis that electrical activity affects neurite elongation in sprouting neurons was tested by stimulating individual snail neurons isolated in cell culture. The findings demonstrated that growth cone advance, and thus neurite elongation, is reversibly stopped during periods when action potentials are experimentally evoked. A decrease in filopodial number and growth cone area was also observed. Thus, action potentials can mediate the cessation of neurite outgrowth and thereby may influence structure and connectivity within the nervous system.     

橄榄成熟胚培养研究

以橄榄常见品种惠圆的成熟胚为外植体，研究橄榄成熟胚培养的方法、培养反应和影响因素。建立了橄榄成熟胚离体无菌培养的有效方法；获得了橄榄无菌胚苗、愈伤组织、气生根和胚状体等4种培养物，为进一步的橄榄离体快速繁殖、细胞悬浮培养、原生质体培养、遗传转化以及离体种质保存等生物技术研究奠定基础。     

维生素C对新生大鼠海马神经细胞生长的影响

取新生大鼠海马组织进行原代体外分散培养,用MTT比色法检测不同浓度维生素C对神经细胞生长的影响,并观察其形态学变化和分化程度。结果表明,2和20nmol/L维生素C组对神经细胞生长的影响与对照组无显著差别(P>0.05);200nmol/L维生素C组能促进神经细胞的存活,与对照组相比差异显著(P<0.01),进一步观察发现,该处理的细胞突起数目、长度、胞体面积均显著高于对照组(P<0.01);2000nmol/L维生素C组可显著减少细胞的存活数,能引起细胞凋亡。提示200nmol/L维生素C对神经细胞生长发育有一定的促进作用。     

水稻悬浮培养细胞在固体和液体培养下的形态发生

藤板５号悬浮培养细胞经适当处理后,在固体分化培养基上形成大量的胚状体。观察到球形胚和胚柄结构,成熟胚状体为圆筒状,芽分生组织为叶原基包裹。胚状体的畸形发育和先熟萌发是导致胚状体苗转换效率低的主要原因。液体培养条件下通过逐步降低２,４－Ｄ浓度（一月内从１．０ｍｇ／１降至０．２ｍ８／１）诱导了体细胞胚胎发生,且胚状体发生数量多,较为同步,细胞分裂也较为旺盛。     

植物离体培养技术在果树育种研究上的应用

本文综述胚胎培养、花药培养、胚乳培养、原生质体培养及其融合,利用培养物获得突变体和超低温保存培养物等植物离体培养技术在果树育种研究上的应用进展,并讨论一些与上述内容有关的问题。     

D1 and D2 dopamine receptor-regulated gene expression of striatonigral and striatopallidal neurons

The striatum, which is the major component of the basal ganglia in the brain, is regulated in part by dopaminergic input from the substantia nigra. Severe movement disorders result from the loss of striatal dopamine in patients with Parkinson's disease. Rats with lesions of the nigrostriatal dopamine pathway caused by 6-hydroxydopamine (6-OHDA) serve as a model for Parkinson's disease and show alterations in gene expression in the two major output systems of the striatum to the globus pallidus and substantia nigra. Striatopallidal neurons show a 6-OHDA-induced elevation in their specific expression of messenger RNAs (mRNAs) encoding the D2 dopamine receptor and enkephalin, which is reversed by subsequent continuous treatment with the D2 agonist quinpirole. Conversely, striatonigral neurons show a 6-OHDA-induced reduction in their specific expression of mRNAs encoding the D1 dopamine receptor and substance P, which is reversed by subsequent daily injections of the D1 agonist SKF-38393. This treatment also increases dynorphin mRNA in striatonigral neurons. Thus, the differential effects of dopamine on striatonigral and striatopallidal neurons are mediated by their specific expression of D1 and D2 dopamine receptor subtypes, respectively.     

3株拮抗酵母菌对苹果采后青霉病的防治效果

在活体和离体条件下,采用刺伤苹果接种酵母菌的方法,研究了3株拮抗酵母菌对扩展青霉(Peni-cillium expansum)引起的苹果采后病害的防治效果。结果表明,3株酵母菌孢子悬浮液对青霉病防治效果显著,防效达80%~96%;3株酵母菌可以在苹果果实伤口处接种后的前3 d快速定殖,在之后的5 d保持稳定;在PDA对峙培养中,酵母菌不能抑制病菌的生长,而在其液体培养中,酵母菌孢子悬浮液能显著抑制青霉病菌孢子的萌发,其上清过滤液和灭菌液不能抑制果实的腐烂,表明其作用机制主要是营养和空间竞争。