一氧化氮在中枢神经系统发育中的作用

一氧化氮作为中枢神经系统内的非经典性细胞递质和信使分子,有着多方面的生物效应。在神经发育的过程中,一氧化氮可通过NO/cGMP系统调节突触的形成及修饰,介导成熟期突触可塑性等过程。本文结合其生物学特性和作用机制就一氧化氮对中枢神经系统发育的影响作一综述。     

神经肌肉连接形成研究进展

神经肌肉连接形成是肌细胞与运动神经元前膜相互识别、相互作用 ,从而逐步形成特异突触结构的复杂过程。突触前分化是通过插入含有活性成分细胞骨架复合体的前体小泡 ,导致功能活性区的快速形成等过程实现的。突触后分化是通过递质受体和突触后致密物的信号传导分子来收集突触后致密物的脚手架分子和稳定突触的结构等来完成的。综述神经肌肉连接形成过程中突触前后膜的特化以及相关分子研究进展。     

脑多肽

构成神经系统的复杂功能是通过神经细胞之间的相互联系来实现的,而这种联系要依靠有关化学物质的传递来完成。这些化学物质可简单地分为二大类:一、多肽类(Peptides),二、非多肽类(Nonpeptides,如,去甲肾上腺素)。有人推测在中枢神经系统中约有40％的突触联系与非多肽类递质有关,其余的突触联系可能主要与多肽类递质有关。从解剖学上,一般把神经分泌与脑多肽联系起来。     

突触前受体与神经传递的调节

神经递质与效应细胞上的受体结合,通过一系列生物化学反应和生物物理的变化而改变突触后膜的机能状态。递质的合成、释放以及与突触后膜受体的结合和失活等过程是神经信息通过突触传递的基础。关于神经末梢递质的释放,直到最近还认为是仅决定于动作电位的频率。近十年来许多实验证明在神经末梢还有突触前受体的存在。无论     

小鼠盆神经初级传入在脊髓的局部调控及与上级神经元的纤维联系

目的:利用重组伪狂犬病毒介导的逆行跨多突触追踪技术,观察小鼠盆神经初级传入在脊髓突触前神经元的形态特征及其与上级神经元的纤维联系。方法:在成年雄性C57小鼠一侧盆神经注射伪狂犬病毒,动物存活一周后灌注取材,在激光共聚焦显微镜下观察全脑的突触前神经元的分布;利用免疫荧光组织化学技术特异性标记脊髓神经元,观察盆神经初级传入的突触前神经元与痛相关神经元的共存情况。结果:将伪狂犬病毒介导的逆行跨多突触病毒注入盆神经后,脊髓和脑内大量核团,如下丘脑、运动皮质、中脑导水管周围灰质、臂旁核和腰骶髓后连合核(DCN)都可观察到密集分布的突触前神经元。利用免疫荧光组织化学染色技术,观察到DCN内存在大量SP受体(SPR)阳性神经元,且SPR阳性神经元与盆神经跨突触标记的突触前神经元不共存,这些突触前神经元主要呈GABA阳性。结论:DCN是盆神经初级传入在脊髓的关键中继部位,内脏伤害性信息可能在DCN处进行初级调控后向上逐级传导。     

第一组代谢型谷氨酸受体在外周痛信号产生中的作用

谷氨酸是脑内最重要的兴奋性递质 ,除参与快速的兴奋性突触传递外 ,还与突触前递质释放、突触传递的长时程增强和长时程抑制、学习和记忆过程、突触发育的可塑性等正常生理功能密切相关。谷氨酸过量时还具有神经毒作用 ,可导致神经元死亡。谷氨酸受体分为两类 :(1)离子型谷氨酸受体 (ionotrop-ic glutam ate receptors,i Glu Rs) ,属于配体门控离子通道 ,包括 NMDA、AMPA和 KA三种亚型 ,均以异源性蛋白的多聚体形式存在 [1 ] ;(2 )代谢型谷氨酸受体 (m etabotropic gluta-mate receptors,m Glu Rs) ,是一组新型的 G-蛋白偶联受体。m …     

大鼠体神经-内脏神经吻合再生后脊髓前角异体神经元的分离和凝集素的表达变化及作用

目的 研究大鼠体神经-内脏神经吻合以及体神经-体神经吻合再生后,凝集素(agrin)在脊髓前角运动神经元中的表达及其差异,探讨异体神经再生中参与突触形成和维持的相关因子.方法 建立大鼠体神经-内脏神经吻合动物模型和体神经-体神经吻合动物模型,通过荧光染料逆行追踪、标记L4脊髓前角支配盆神经节的运动神经元(异体神经元).流式细胞仪分选被标记细胞,用实时定量PCR测定分选细胞中agrin的mRNA水平.用荧光染料顺行追踪结合免疫荧光标记盆神经节处的新突触.结果 模型鼠吻合再生4个月后,体神经能够再生并替代内脏神经长入盆神经节,并最终形成新的突触结构.在激光共焦显微镜下观察到了这种结构.应用荧光染料逆行追踪结合流式细胞分选技术能满意分离出L4脊髓前角的运动神经元.实时定量PCR测得agrin在各组分选神经元中均有表达,模型组中agrin表达水平较模型对照组和正常组有少许降低(P＜0.05).结论 异体神经再生长入盆节后能够形成新的突触结构,agrin参与形成和维持这种突触结构,其表达量的少许下调,可能与支配的靶器官改变而引起相应内环境的改变有关.     

大鼠脊髓后角浅层初级传入C纤维内μ阿片受体的免疫组织化学定位光镜与电镜研究

目的在光镜及电镜下观察大鼠脊髓后角内μ阿片受体(MOR)与C纤维的关系,为进一步揭示阿片镇痛的突触机制提供形态学证据. 方法根据辣椒素对初级传入神经中C纤维的特异性神经毒性,在大鼠蛛网膜下腔注射辣椒素以毁损C纤维,用免疫组织化学ABC法比较脊髓后角内MOR免疫反应性的变化;根据西非单叶豆同工凝集素I-B4(griffonia simplicifolia isolectin I-B4,I-B4)与初级传入C纤维选择性结合的特性,应用双标(免疫)组织化学电镜技术(ABC-纳金法)分别标记脊髓后角内I-B4结合位点和MOR. 结果大鼠蛛网膜下腔注射辣椒素3～7d后,其脊髓后角Ⅰ～Ⅱ层内的MOR免疫反应性较对照动物明显减弱;电镜下在大鼠脊髓后角浅层内观察到,MOR不仅定位于树突内,也分布在含I-B4结合位点的C纤维终末内.无论在树突内还是在轴突终末内,MOR主要分布在非突触部位,仅少量MOR与突触前膜和/或突触后膜有关. 结论脊髓后角中部分MOR来源于辣椒素敏感的C纤维,外源性吗啡或内源性吗啡样物质如内吗啡肽等MOR激动剂在脊髓后角内既可通过突触后(树突内)的MOR发挥作用,也可通过突触前(轴突终末内)的MOR对C纤维产生突触前抑制效应,而且在此过程中,MOR激动剂在非突触部位的作用可能是主要的.     

嗅鞘细胞移植促进脊髓损伤模型大鼠修复损伤区组织的超微结构特征

文题释义： 嗅鞘细胞：是一种嗅神经的支持细胞,它起源于嗅基底膜,分布在嗅球,嗅神经和嗅中枢。位于中枢和外周神经系统过渡区,具有降解抑制再生分子、分泌不同神经营养因子、促进神经轴突和髓鞘的再生、改善脊髓损伤后的微环境等重要作用。 超微结构：通过透射电子显微镜观察脊髓损伤后损伤部位神经元的细胞膜、细胞器(高尔基复合体,尼氏体,内质网、核糖体、神经微丝、微管)、细胞核(核仁、核周体);髓鞘,轴突,突触,胶质瘢痕等亚细胞水平的变化。 背景：嗅鞘细胞移植治疗脊髓损伤是目前的研究热点,其研究主要探讨脊髓损伤后微环境的影响,嗅鞘细胞移植对脊髓损伤后脊髓超微结构的影响未见报道。 目的：观察脊髓损伤后损伤部位神经细胞、轴突、髓鞘、突触和胶质瘢痕的超微结构以及嗅鞘细胞移植对大鼠损伤脊髓的保护和神经修复再生的影响。 方法：实验方案经西安交通大学医学部生物医学伦理委员会批准(批准号2018-2048)。将成年健康雌性SD大鼠20只随机分成3组：空白组(4只)仅仅切除T₁₀全部椎板及T₉, T₁₁部分椎板,未对脊髓作其他处理;DF12组(8只)切断脊髓,注射DF12培养液;嗅鞘细胞移植组(8只)切断脊髓,进行嗅鞘细胞移植。于脊髓损伤后1,7,28,56 d,对各组大鼠麻醉后取出脊髓,透射电镜观察脊髓损伤区神经细胞超微结构的变化。 结果与结论：①与空白组比较,DF12组大鼠脊髓损伤区神经元胞体内细胞器明显减少,轴突、髓鞘和突触的超微结构发生明显的变化;嗅鞘细胞移植组损伤区的神经元胞体内细胞器明显增加,核仁明显,促进轴突、髓鞘和突触的再生,且胶质瘢痕明显较少;②嗅鞘细胞移植组大鼠星形胶质细胞和毛细血管周细胞的反应比较轻微;③结果说明,脊髓损伤后嗅鞘细胞移植可有效地保护脊髓损伤区的神经组织,促进轴突、髓鞘和突触的再生,抑制神经胶质和周围细胞的增生反应,从而使损伤后微环境有利于神经元、轴突和突触再生。ORCID: 0000-0001-6049-2551(王国毓) 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

LTP形成机制的研究进展

突触传递的长时程增强 (LTP)是学习记忆的神经基础之一 ,是突触可塑性的功能性指标之一 ,也是研究学习记忆的理想模型。LTP是突触前后机制共同作用的结果 ,包括诱导和维持 2个阶段。LTP的形成与突触前递质的释放、突触后相关受体通道以及各种蛋白激酶、逆行信使、即早基因等密切相关。     

Photoperiodicity and the function of the hypophysis and the adrenal cortex

Summary The ACTH content of the hypophysis of rats rises from a minimum in the morning to a maximum in the evening hours. These fluctuations are associated with the diurnal rhythm of light and darkness, and are abolished under conditions of continual light or darkness for 30 days. Rhythmic fluctuations of the ascorbic acid content of the adrenals are also found, with maximum values in the evening, and these are likewise abolished by maintenance under conditions of constant illumination.Presented by Active Member AMN SSSR V. V. Parin     

Organization and distribution of the upper and lower esophageal motoneurons in the medulla and the spinal cord of the rat

The upper cervical esophagus is exerted on swallowing and peristalsis by somatic and visceral motoneurons, whereas the lower esophagus is exerted on only peristalsis by visceral motoneurons. We examined the origin of the esophageal motoneurons and whether there were any differences between the distributions of the upper and the lower esophageal motoneurons in the medulla and the spinal cord using cholera toxin subunit b (CTb) as the retrograde tracer. Following injection of CTb into the cervical esophagus resulted in heavy labeling of the neurons in the nucleus ambiguus including the compact (AmC), semicompact (AmS) and loose (AmL) formations, and the medial column of lamina IX at the C1-C5 levels of the cervical spinal cord corresponding to the spinal accessory nucleus. A few labeled neurons were found in the inferior salivatory nucleus, the rostral division of the dorsal motor nucleus of the vagus (DMX), the accessory facial nucleus and the lateral column of lamina IX at the C2 and C3 levels. All these labeled neurons showed ChAT immunoreactivity. When CTb was injected into the cut end of the unilateral recurrent laryngeal nerve, many labeled neurons were found in the ipsilateral AmC, the AmL, and the bilateral medial column at the C1 and C2 levels. Following injection of CTb into the subdiaphragmatic esophagus resulted in heavy labeling of the neurons only in the AmC and the DMX. When CTb was injected into the sternomastoid muscle, many labeled neurons were found in the medullary reticular formation, the facial nucleus, the medial column at the C1-C3, C5 and C6 levels, and the lateral column at the C2, C3, C5 and C6 levels. Injections of a Fluoro-Gold into the cervical esophagus and a CTb into the sternomastoid muscle or the subdiaphragmatic esophagus in the same animal showed many double labeled neurons in the medial column of the accessory nucleus at the C1 and C2 levels, but no double labeled neurons in the AmC. These results indicated that the upper cervical esophagus is innervated by the visceral medullary vagal motoneurons as well as the somatic spinal accessory motoneurons. The lower esophagus is innervated only by the visceral medullary vagal motoneurons.     

Anatomic considerations and the relationship between the piriformis muscle and the sciatic nerve

Stating background  The piriformis syndrome is one of the non-discogenics causes of sciatica. It results from the compression of the sciatic nerve (SN) by the piriformis muscle (PM) in the neutral and piriformis stretch test position. The evidence of the increase in pain in the test position requires a detailed anatomical study addressing the changes that occurred in the SN and PM anatomy during the test position. The aim of this study is to examine this relationship morphometrically. Materials and methods  A total of 20 right and left lower limbs of ten adult cadavers were examined. The SN and the PM were made visible. The location of the SN was evaluated with respect to the consistent bony landmarks, including the greater and the lesser trochanter of the femur, the ischial tuberosity, the ischial spine of the hip bone, the posterior inferior iliac spine of the hip bone and the posterior superior iliac spine of the hip bone. The study was done in both neutral and test positions (i.e., 30° adduction 60° flexion and approximately 10° medial rotation position of the hip joint). Results  The width of the greater sciatic notch was 63.09 ± 13.59 mm. The length of the lower edge of the PM was 95.49 ± 6.21 mm, and whereas the diameter of the SN where it emerged from the infrapiriforme was 17.00 ± 3.70 mm, the diameter decreased to 11.03 ± 2.52 mm at the level of the lesser trochanter of the femur. The SN intersected the PM most commonly in its medial second quarter anatomically. The vertical distance between the medial edge of the SN–PM intersection point and the ischial tuberosity was 85.62 ± 17.23 and 72.28 ± 7.56 mm (P < 0.05); the angle between the SN and the transverse plane was 66.36° ± 6.68° and 71.90 ± 8.48° (P < 0.05); and the vertical distance between the medial edge of the SN and the apex of the ischial spine of the hip bone was 17.33 ± 4.89 and 15.84 ± 4.63 mm (P > 0.05), before and after the test position, respectively. Conclusion  This study provides helpful information regarding the course and the location of the SN. The presented morphometric data also revealed that after stretch test position, the infrapiriforme foramen becomes narrower; the SN becomes closer to the ischial spine of the hip bone, and the angle between the SN and the transverse plane increases. This study confirmed that the SN is prone to be trapped in the test position, and diagnosis of this situation requires dynamic MR and MR neurography study.     

空肠和回肠直动脉及器官表面动脉的观测

目的　通过对空、回肠直动脉分支类型的观察、测量不同类型直动脉管径、间距以及器官表面动脉吻合网面密度 ,探讨空、回肠血供形态的异同 ,为临床空、回肠疾病手术、器官移植、介入治疗提供形态学依据。方法　选取 15具成人及 2～ 6岁小儿 10具进行股动脉插管、乳胶灌注后解剖剥离直动脉 ,将空回肠均分 5段观测相关指标。结果　成人空肠 (1、2段 )及回肠 (3～ 5段 )直动脉起始处外管径 (mm)分别为 0 6 8± 0 18、0 72± 0 0 1、0 6 1± 0 0 2、0 5 3± 0 0 3和 0 5 1± 0 0 1,相邻分支间距 (mm)分别为 2 89± 1 72、2 79± 2 0 6、2 2 1± 1 6 4、2 17± 1 17及 2 85± 0 4 6 ;空、回肠直动脉长、短干型分支供血能力不同 ;空肠器官表面动脉吻合网面密度大于回肠。结论　直动脉分支类型、管径、间距及器官表面动脉吻合网面密度对空、回肠血供影响较大。