神经生长因子对严重烫伤大鼠纹状体及海马NOS阳性神经元？…

应用ＮＡＤＰＨ－ｄ酶组织化学方法,观察了大鼠烫伤后脑内ＮＯＳ阳性神经元素数目和阳性反应面积的变化及ＮＧＦ对其影响。结果显示：大鼠体表烫伤后３天,纹状体ＮＯＳ阳性神经元数目明显增加,染色呈强阳性,阳性反应面积增加。海马的ＮＯＳ阳性神经元数变化不明显,仅见阳性反应面积增加,ＮＧＦ可降低纹状体的ＮＯＳ阳性神经元数目、阳性反应面积,ＮＯＳ阳性神经元着色较淡;海马的ＮＯＳ阳性瓜面积减少,ＮＧＦ的作用与－Ｎ     

神经生长因子对严重烫伤大鼠纹状体及海马NOS阳性神经元的影响

应用ＮＡＤＰＨ－ｄ 酶组织化学方法,观察了大鼠烫伤后脑内ＮＯＳ阳性神经元数目和阳性反应面积的变化及ＮＧＦ对其影响。结果显示：大鼠体表烫伤后３ 天,纹状体ＮＯＳ阳性神经元数目明显增加,染色呈强阳性,阳性反应面积增加。海马的ＮＯＳ阳性神经元数变化不明显,仅见阳性反应面积增加,ＮＧＦ可降低纹状体的ＮＯＳ阳性神经元数目、阳性反应面积,ＮＯＳ阳性神经元着色较淡;海马的ＮＯＳ阳性反应面积减少,ＮＧＦ的作用与Ｌ－ＮＡＭＥ抑制ＮＯＳ的作用相似。这些结果提示,ＮＧＦ可能通过降低ＮＯＳ活性,从而减轻烫伤引起的神经元损伤。     

大鼠脑片体外缺血状态纹状体中一氧化氮合成酶阳性神经元…

无糖无氧人工脑脊液模拟脑缺血状态，用还原型尼克酰胺腺嘌呤二核苷酸脱氢酶反应观察大鼠离体脑片纹状体中一氧化氮合成酶阳性神经元的时相变化及神经损伤，结果显示：在缺血损伤严重的纹状体，一氧化氮合成酶阳性神经元缺血早期明显增多并深染，１ｈ后显著减少，提示纹状体的一氧化氮合成酶阳性神经元本身存在有限的抗损伤能力。     

左旋多巴对体外培养大鼠纹状体的神经毒性及其保护方法的研究

目的 研究左旋多巴（Ｌ－ｄｏｐａ）的神经毒性及其神经保护方法。方法 用胎盼兰染色法检测Ｌ－ｄｏｐａ和抗氧化剂还原型谷胱甘肽（ＧＳＨ）、ＮＭＤＡ受体拮抗剂ＭＫ８０１对体外培养大鼠纹状体的神经元活力的影响。结果 Ｌ－ｄｏｐａ使大鼠纹状体神经元活力明显下降（Ｐ〈０．０１）,ＧＳＨ和ＭＫ８０１可明显减轻Ｌ－ｄｏｐａ引起的纹状体神经元活力下降（Ｐ〈０．０１）。结论 Ｌ－ｄｏｐａ可能通过氧化应激和兴奋ＮＭＤＡ受体两个途径发挥其神经毒性,抗氧化剂或ＮＭＤＡ受体拮抗剂与Ｌ－ｄｏｐａ合用可能减轻Ｌ－ｄｏｐａ的神经毒性。     

铁离子对黑质纹状体多巴胺神经元毒性作用的实验研究

目的 探讨铁离子对黑质纹状体多巴胺神经元的毒性作用。方法 采用立体定向偏侧大鼠黑质内注入50μg FeCl3和FeCl2，4周后用阿朴吗啡诱导动物行为学变化，高效液相色谱(HPLC)检测纹状体内多巴胺、去甲肾上腺素、肾上腺素递质含量的变化，免疫组化观察黑质多巴胺神经元和胶质细胞的改变。结果 FeCL3和FeCL2均可引起注射侧纹状体内DA含量选择性降低，而NA、A含量无显著改变；注射侧黑质内DA神经元显著缺失、胶质细胞显著增生；FeCL3组阿朴吗啡诱导大鼠向同侧旋转行为，FeCL2组大鼠于术后即出现特征性自发性对侧旋转行为，阿朴吗啡不能诱发其旋转。结论 铁离子对黑质纹状体多巴胺神经元具有毒性作用，Fe^3 作用最强，胶质细胞的增生可能参与了这一毒性作用过程。     

左旋多巴对帕金森病大鼠黑质多巴胺能神经元及纹状体多巴胺递质的影响

目的　研究长期应用左旋多巴对帕金森病 (PD)大鼠黑质多巴胺 (DA)能神经元和DA递质的影响。方法　采用 6 羟基多巴胺 (6 OHDA)制备部分损毁和严重损毁的PD大鼠模型 ,给两种模型口服不同剂量左旋多巴 /苄丝肼 3个月 ,通过观察大鼠旋转行为、酪氨酸羟化酶 (TH)免疫组化染色和高效液相色谱 电化学检测仪 (HPLC ECD)检测纹状体单胺类递质 ,研究左旋多巴对PD大鼠残存的黑质DA能神经元的影响。结果　 (1)左旋多巴对PD大鼠的旋转行为无明显影响 ;(2 )TH阳性细胞数损毁侧 /非损毁侧比值在左旋多巴喂药组和不喂药对照组的差异无显著意义 (P >0 0 5 ) ;(3)在严重损毁组 ,大剂量左旋多巴使PD大鼠损毁侧DA和 3,4二羟基苯乙酸 (DOPAC)水平明显升高(P <0 0 1)。结论　长期使用左旋多巴对 6 OHDA单侧损毁的PD大鼠残存的黑质DA能神经元无毒性作用。     

脑创伤后NGF对神经干细胞Nestin蛋白表达的影响

目的　研究脑创伤后外源性神经生长因子 (NGF)对神经干细胞Nestin蛋白表达的影响及其意义。方法　建立大鼠流体脑创伤模型 ,采用免疫细胞化学及图像分析等方法 ,观察脑创伤后非NGF处理组和NGF处理组Nestin蛋白表达的变化。结果　成年大鼠Nestin阳性细胞主要位于室管膜下组织 ,细胞的形态主要是胶质细胞。脑创伤后Nestin阳性细胞在室管膜下反应性增加 ,以伤后 7d明显 ,同时在创伤区域周围也可见到大量的Nestin阳性细胞 ,并在伤后 14d继续维持其反应性增加。NGF处理组伤后 7dNestin阳性细胞在伤灶周围更加明显 ,为 2 8.7± 3.8,比同时相点的非NGF处理组明显增加 (P <0 .0 1)。结论　外源性NGF能明显促进脑创伤后Nestin阳性细胞数量的增加 ,增强星形胶质细胞对脑创伤的反应并使其表现有神经干细胞的特征 ,参与神经细胞的再生和重塑。     

美多巴对早期帕金森病纹状体多巴胺能神经元的影响

帕金森病(Parkinson's disease，PD)，又名震颤麻痹。临床上以锥体外系运动障碍为特征，表现为运动迟缓、静止性震颤、肌强直及自主神经功能障碍等症状。PD的病理特征是中脑黑质的多巴胺能神经元(Dopaminergic neuron，DN)缓慢进行性变性和消失，导致黑质、纹状体多巴胺转运体(Dopamine transporter，DAT)、多巴胺(Dopamine，DA)显著减少。     

刺五加皂甙对神经元谷氨酸毒性损伤的保护作用

目的:观察不同谷氨酸浓度和谷氨酸作用不同时间对神经元活性的影响,探讨细胞损伤后刺五加皂甙(ASS)的有效保护浓度。方法:取孕13～15dICR小鼠,无菌条件下对胎鼠大脑皮层神经元进行原代分离培养,建立谷氨酸诱导的皮层神经元损伤模型。用MTT、LDH测定神经元活性,用硝酸还原酶法测定细胞培养上清液中NO的含量,用流式细胞仪检测细胞凋亡率,并在电镜下观察细胞形态学变化。结果:①经谷氨酸处理的神经元,其细胞存活率呈剂量和时间依赖下降、ASS能不同程度提高细胞存活率。②谷氨酸处理组的神经元凋亡率、LDH释放量和NO含量均升高,与正常对照组及ASS组比较有明显差异(P<0.01)。结论:一定浓度的ASS对谷氨酸引起的神经元损伤有保护作用;ASS可能是通过抑制NO的释放和稳定细胞膜,拮抗细胞元损伤。     

神经生长因子对严重烫伤大鼠海马神经元的保护作用

观察大鼠严重烫伤时海马神经元的病理变化,探讨ＮＧＦ对烫伤大鼠海马神经元的保护作用及其可能机制。ＳＤ大鼠侧脑室埋管,分成假烫组、烫伤组、烫伤＋ ＮＧＦ小剂量组、烫伤＋ ＮＧＦ大剂量组;大鼠在麻醉下造成３０％ ＴＢＳＡⅢ度烫伤,伤后３ ｄ,测定脑组织含水量,海马乳酸脱氢酶（ＬＤＨ）和一氧化氮（ＮＯ）的含量;部分脑组织做病理切片,尼氏染色。烫伤后７２ ｈ,脑组织含水量增加,海马出现明显的病理变化,尼氏小体减少或消失,胞体肿胀;ＬＤＨ和ＮＯ的含量明显增加;给予ＮＧＦ后,能明显改善上述病理变化,并能降低脑组织含水量、海马ＬＤＨ 和ＮＯ的含量。烫伤可引起海马神经元损伤、海马组织ＮＯ含量升高;ＮＧＦ对烫伤后海马神经元的损伤有保护作用,并能降低ＮＯ含量。     

Mechanism of resistance to NO-induced neurotoxicity in cultured rat dopaminergic neurons

We previously reported that mesencephalic dopaminergic neurons are resistant to cytotoxicity induced by nitric oxide (NO). This study investigated the intracellular mechanism that protects dopaminergic neurons against NO toxicity in rat mesencephalic cultures. Peroxynitrite anion, an active metabolite of NO, caused significant cytotoxic effects against dopaminergic and nondopaminergic neurons, but NO caused cytotoxic effects restricted to nondopaminergic neurons. In addition, we studied the effects of ascorbate, an anti-oxidant, on NO-induced neurotoxicity against dopaminergic neurons and found that coadministration of ascorbate failed to affect resistance against NO-induced neurotoxicity. These findings suggest that the protecting mechanism from NO neurotoxicity in dopaminergic neurons is based on inhibition of conversion of NO to peroxynitrite anion, is independent of the NO redox state, and is possibly due to suppression of superoxide anion production. Furthermore, we investigated NO-induced neurotoxicity with or without pretreatment with sublethal doses of methylphenylpyridium ion (MPP⁺). Following pretreatment with 1 μM MPP⁺, which did not show significant cytotoxic effects against dopaminergic neurons, NO demonstrated significant cytotoxicity. Therefore, MPP⁺ may inhibit the protecting systems from NO neurotoxicity in dopaminergic neurons. © 1996 Wiley-Liss, Inc.     

D-deprenyl protects nigrostriatal neurons against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced dopaminergic neurotoxicity

Selegiline (L-deprenyl) is believed to render protection against l-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-neurotoxicity to a significant extent via a free radical scavenging mechanism, which is independent of its ability to inhibit monoamine oxidase-B (MAO-B) in the brain. We investigated the hydroxyl radical (.OH) scavenging action and neuroprotective effect of D-deprenyl, its less active isomer, in MPTP-induced dopaminergic neurotoxicity in mice to test whether the chemical structure of the molecule or its biological effects contribute to this property. To achieve this goal we studied the effects of D-deprenyl on: (1).OH production in a Fenton reaction; (2) MPTP-induced.OH generation and dopamine (DA) depletion in vivo, employing a sensitive HPLC-electrochemical procedure; and (3) formation of MPP(+) in vivo in the striatum following systemic administration of MPTP, employing an HPLC-photodiode array detection system. D-deprenyl inhibited ferrous citrate-induced.OH in vitro (0.45 microM) and MPTP-induced.OH in vivo in substantia nigra (SN) and in the striatum (1.0 mg/kg, i.p.). D-deprenyl did not, but L-deprenyl (0.5 mg/kg dose) did significantly inhibit formation of MPP(+) in the striatum 90 min following systemic MPTP injection. It failed to affect MAO-B activity at 0.5 mg/kg in the striatum, but effectively blocked MPTP-induced striatal DA depletion. The potency of D-deprenyl to scavenge MPTP-induced.OH in vivo and to render protection against the dopaminergic neurotoxicity without affecting dopamine turnover, MAO-B activity, or formation of MPP(+) in the brain indicates a direct involvement of.OH in the neurotoxic action of MPTP and antioxidant effect in the neuroprotective action of deprenyl.     

Silymarin protects dopaminergic neurons against lipopolysaccharide-induced neurotoxicity by inhibiting microglia activation

An inflammatory response in the central nervous system mediated by activation of microglia is a key event in the early stages of the development of neurodegenerative diseases. Silymarin is a polyphenolic flavanoid derived from milk thistle that has anti-inflammatory, cytoprotective and anticarcinogenic effects. In this study, we first investigated the neuroprotective effect of silymarin against lipopolysaccharide (LPS)-induced neurotoxicity in mesencephalic mixed neuron-glia cultures. The results showed that silymarin significantly inhibited the LPS-induced activation of microglia and the production of inflammatory mediators, such as tumour necrosis factor-alpha and nitric oxide (NO), and reduced the damage to dopaminergic neurons. Therefore, the inhibitory mechanisms of silymarin on microglia activation were studied further. The production of inducible nitric oxide synthase (iNOS) was studied in LPS-stimulated BV-2 cells as a model of microglia activation. Silymarin significantly reduced the LPS-induced nitrite, iNOS mRNA and protein levels in a dose-dependent manner. Moreover, LPS could induce the activation of p38 mitogen-activated protein kinase (MAPK) and c-jun N-terminal kinase but not extracellular signal-regulated kinase. The LPS-induced production of NO was inhibited by the selective p38 MAPK inhibitor SB203580. These results indicated that the p38 MAPK signalling pathway was involved in the LPS-induced NO production. However, the activation of p38 MAPK was not inhibited by silymarin. Nevertheless, silymarin could effectively reduce LPS-induced superoxide generation and nuclear factor kappaB (NF-kappaB) activation. It suggests that the inhibitory effect of silymarin on microglia activation is mediated through the inhibition of NF-kappaB activation.     

塞来昔布对脂多糖诱导的原代多巴胺能神经元变性的保护作用

目的研究COX-2选择性抑制剂塞来昔布对脂多糖诱导的中脑原代多巴胺能神经元变性的保护作用及其机制。方法将培养7d的孕14d SD大鼠胚胎中脑原代细胞随机分为4组:对照组、脂多糖(LPS)组(20ng/ml)、塞来昔布(20μmol/L) 脂多糖组、单纯塞来昔布组。培养72h后使用免疫荧光染色观察酪氨酸羟化酶(TH)、OX-42阳性细胞数目和形态变化,放免法测定上清液中前列腺素E2(PGE2)和肿瘤坏死因子-α(TNF-α)水平。结果塞来昔布 LPS组和LPS组比较:TH阳性细胞数目明显增多,分别为对照组的69%和48%(P<0.05);OX-42阳性细胞数目明显减少,分别为对照组的2和3.48倍(P<0.05)。形态上分析塞来昔布显著改善LPS对TH阳性细胞的损伤程度和抑制LPS诱导的小胶质细胞体积增大、形态不规则。同时抑制LPS诱导的PGE2和TNF-α含量的增加(P<0.05)。结论塞来昔布通过抑制小胶质细胞激活以及COX-2表达,减少细胞外PGE2、TNF-α水平发挥其神经保护作用。     

Immobilization-induced changes in the response of striatal neurons to dexamphetamine

1. 1. Bipolar multiple unit recording electrodes were implanted in the striata of male Long-Evans rats 5–7 days prior to experimentation.

2. 2. In subsequent experiments, striatal neuronal activity in response to dexamphetamine (1.0 or 2.5 mg/kg i.p.) was recorded in either freely moving or immobilized, artificially-respired rats.

3. 3. Whereas dexamphetamine produced only excitation of striatal neurons in freely moving animals, a multiplicity of responses, ranging from excitation to inhibition, and including biphasic as well as no change responses were observed in immobilized animals.

4. 4. It is concluded that the absence of dexamphetamine-induced behavior in immobilized animals modifies the striatal neuronal response to dexamphetamine, possibly through alteration of the activity of excitatory striatal afferents.

Monoamine oxidase B inhibitor selegiline protects young and aged rat peripheral sympathetic neurons against 6-hydroxydopamine-induced neurotoxicity

Selegiline is a selective and irreversible monoamine B inhibitor with the capacity to increase the level of several antioxidative enzymes in rat brain. It can protect adrenergic neurons against injury induced by neurotoxins such as MPTP, DSP-4 and AF64A in animal studies. In addition, the protective action is not limited to catecholaminergic cells, as selegiline can also minimize the loss of developing motoneurons after axotomy. The aim of this study was to determine whether selegiline can protect peripheral catecholaminergic neurons against the neurotoxic effect of 6-OHDA. This kind of protective effect against 6-OHDA neurotoxicity has not been reported before. Wistar albino male rats aged 4 or 24 months were treated with selegiline or saline solution 1 h before 6-OHDA injection. At 2 weeks after the 6-OHDA injection, the superior cervical ganglia (SCG) and submandibular glands (SMG) were studied using catecholamine histofluorescence and immunohistochemistry for tyrosine hydroxylase (TH). The number of TH-positive cells in the SCG and the length and number of adrenergic nerve fibers in the SMG were quantified. Our findings showed that 6-OHDA caused a reduction of TH immunoreactivity and catecholamine histofluorescence in neuronal somata, as well as a decrease in the number and length of adrenergic nerve fibers in the submandibular gland. Selegiline pretreatment protected SCG neurons and their postganglionic nerve fibers in SMG against these changes in a dose-dependent manner. The mechanism through which selegiline exerts its neuroprotective effect is as yet unknown. Received: 5 September 1995 / Revised, accepted: 13 November 1995     

Neurochemical and electrophysiological characteristics of rat striatal neurons in primary culture

Neurons maintained in dispersed primary culture offer a number of advantages as a model system and are particularly well-suited for studies of the intrinsic electrical properties of neurons by patch clamp. We have characterized the immunocytochemical and electrophysiological properties of cultured rat striatal neurons as they develop in vitro in order to compare this model system with the known properties found in vivo. We found a high abundance of cells in vitro corresponding to the principal striatal output neuron, the medium spiny neuron. Immunocytochemical studies indicate that these cells have both dopamine-1 and dopamine-2 receptors and that there is overlap in their expression within the population of neurons. Semiquantitative analysis revealed bimodal distributions of dopamine receptor expression among the population of neurons. The principal peptide neurotransmitters substance P and enkephalin were present but at reduced levels compared with adult preparations. Other striatal markers such as calbindin, calretinin, and the cannabinoid-1 receptor were abundant. An immunocytochemical survey of voltage-gated K(+) channel subunits characteristic of adult tissue demonstrated the presence in vitro of Kv1.1, Kv1.4, Kv4.2, Kv4.3, and Kvbeta1.1, which have been associated with the rapidly inactivating currents. Electrophysiological studies employing voltage clamp revealed that outward currents had a large inactivating (A-type) component characteristic of mature basal ganglia. Current clamp studies reveal complex spontaneous firing patterns in a subset of neurons, including bursting behaviors superimposed on a slow depolarization. The inward rectifying channels Kir2.1 and Kir2.3, which are specific to particular compartments in adult striatum, were present in culture.     

NGF mRNA is expressed by GABAergic but not cholinergic neurons in rat basal forebrain

Nerve growth factor (NGF) supports the survival and biosynthetic activities of basal forebrain cholinergic neurons and is expressed by neurons within lateral aspects of this system including the horizontal limb of the diagonal bands and magnocellular preoptic areas. In the present study, colormetric and isotopic in situ hybridization techniques were combined to identify the neurotransmitter phenotype of the NGF-producing cells in these two areas. Adult rat forebrain tissue was processed for the colocalization of mRNA for NGF with mRNA for either choline acetyltransferase, a cholinergic cell marker, or glutamic acid decarboxylase, a GABAergic cell marker. In both regions, many neurons were single-labeled for choline acetyltransferase mRNA, but cells containing both choline acetyltransferase and NGF mRNA were not detected. In these fields, virtually all NGF mRNA-positive neurons contained glutamic acid decarboxylase mRNA. The double-labeled cells comprised a subpopulation of GABAergic neurons; numerous cells labeled with glutamic acid decarboxylase cRNA alone were codistributed with the double-labeled neurons. These data demonstrate that in basal forebrain GABAergic neurons are the principal source of locally produced NGF. © 1995 Wiley-Liss, Inc.