Formation of new corticorubral synapses as a mechanism for classical conditioning in the cat

An electron microscopic quantitative study of corticorubral synapses was performed in the cat which acquired classical conditioning. Conditioned stimulus was applied to the cerebral peduncle and the unconditioned stimulus was an electrical shock to the forelimb skin. The proportion of corticorubral synapses contacting with somata and proximal dendrite was increased after conditioning. It was suggested that collateral sprouting and the formation of new synapses underlie classical conditioning.     

Cortical projection patterns of magnocellular basal nucleus subdivisions as revealed by anterogradely transportedPhaseolus vulgaris leucoagglutinin

The present paper deals with a detailed analysis of cortical projections from the magnocellular basal nucleus (MBN) and horizontal limb of the diagonal band of Broca (HDB) in the rat. The MBN and HDB were injected iontophoretically with the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L). After immunocytochemical visualization of labeled efferents, the distribution of projections over the cortical mantle, olfactory regions and amygdala were studied by light microscopy. Based on differences in cortical projection patterns, the MBN was subdivided in anterior, intermediate and posterior portions (MBNa, MBNi and MBNp). All subdivisions maintain neocortical projections and are subject to an anterior to posterior topographic arrangement. In the overall pattern, however, the frontal cortex is the chief target. Furthermore, all MBN parts project to various regions of meso- and allocortex, which are progressively more dense when the tracer injection is more anteriorly placed. The most conspicuous finding, however, was a ventrolateral to dorsomedial cortical projection pattern as the PHA-L injection site moved from posterior to anterior. Thus, the posterior MBN projects predominantly to lateral neo- and mesocortex while the anterior MBN sends more fibers to the medial cortical regions. Furthermore, the MBNa is a source of considerable afferent input to the olfactory nuclei and as such should be regarded as a transition to the HDB. The HDB, apart from projecting densely to olfactory bulb and related nuclei, maintains a substantial output to the medial prefrontal cortical regions and entorhinal cortex, as well. Comparison of young vs aged cases indicate that aging does not appear to have a profound influence on cortical innervation patterns, at least as studied with the PHA-L method.     

Isthmotectal axons make ectopic synapses in monocular regions of the tectum in developing Xenopus laevis frogs.

During the development of binocular maps in the tectum of Xenopus laevis, axons that relay input from the ipsilateral eye via the nucleus isthmi undergo a prolonged period of shifting connections. This shifting accompanies the dramatic change in eye position that takes place as the laterally placed eyes of the tadpole move dorsofrontally. There is a concomitant expansion of the proportion of tectum that receives contralateral retinotectal input corresponding to the binocular portion of the visual field. Electrophysiological recording demonstrates that ipsilateral units are present in those rostral tectal zones, and anatomical methods show that the isthmotectal axons arborize densely in the rostral region but also extend sparser branches into the caudal zone, which is occupied by contralateral inputs with receptive fields in the monocular zone of the visual field. A mechanism that aligns the ipsilateral and contralateral maps is activity-dependent stabilization of isthmotectal axons that exhibit firing patterns correlated with those of nearby retinotectal axons. In order for activity patterns to function in stabilizing correct connections and promoting the withdrawal of incorrect connections, synaptic communication of some sort is hypothesized to be essential. We have investigated whether isthmotectal axons make morphologically identifiable synapses during development and where such synapses are located. We find evidence for morphologically identifiable synapses in all regions of the tectum, along with many growth cones and structures that are probably immature synapses. As in the adult, the synapses contain round, clear vesicles, have asymmetric specializations, and terminate on structures that appear to be dendrites. In both adult and tadpole, the rarity of serial synapses involving isthmotectal terminals suggests that the interactions between retinotectal and isthmotectal inputs are mediated by postsynaptic dendrites.     

大鼠室旁核内催产素免疫阳性细胞树突棘样结构在脱水状态下的改变

树突棘，室旁核，催产素，脱水，免疫组化，大鼠下丘脑内催产素大细胞神经分泌细胞与水盐代谢的调节有关，并伴有细胞形态的改变如细胞体积的增大及细胞膜与细胞膜间接触的增加和多突触的形成等。本文用免疫组化法发现在脱水状态下室旁核的催产素免疫阳性神经元上树突棘样结构有所增加。光镜观察并计算室旁核前大细胞亚核、内侧大细胞亚核及后大细胞亚核中含树突棘样结构的催产素神经元百分数变化，显示正常大鼠室旁核神经元树突棘样结构多位于树突干上，少数在胞体上。前大细胞亚核含树突棘样结构的细胞百分数为２１．２７％，内侧大细胞亚核为３０．２２％，后大细胞亚核为２０．２２％。轻度脱水大鼠室旁核含树突棘样结构细胞百分数显著增加（前大细胞亚核：２８．６５％，Ｐ＜０．０５；内侧大细胞亚核：３５．５３％，Ｐ＞０．０５；后大细胞亚核：３４．７８％，Ｐ＜０．０１）。细胞上树突棘样结构数也增加，其体积略为增大。重度脱水大鼠室旁核中树突棘样结构细胞百分数增加较小，仅后大细胞亚核内有显著变化（２７．１３％，Ｐ＜０．０５）。不同程度脱水组之间无显著变化。结果说明脱水可引起神经元膜结构的改变。树突棘样结构数变化是否与新突触的形成有直接关系？尚待进一步证实。     

颈交感神经对血管源性头痛痛觉传导的影响

目的采用电刺激大鼠上矢状窦(SSS)区硬脑膜,观察颈上交感神经节(SCG)摘除术前后在延髓和上颈段三叉神经脊束核一氧化氮合酶(NOS)阳性神经元数目的变化,以探讨交感神经系统在血管源性头痛(如偏头痛)涉及的伤害觉信息传递中的作用。方法以雄性SD大鼠(体重为220～250g)为实验对象,行颈上交感神经节摘除术后再手术暴露其SSS,然后电刺激SSS区硬脑膜,应用免疫组织化学染色技术,观察延髓和上颈段三叉神经脊束核NOS表达的变化。结果NOS免疫反应阳性神经元主要分布在三叉神经脊束核和上颈段脊髓的第Ⅰ、Ⅱ板层,双侧对称。假手术对照组、SCG摘除组每张切片的NOS阳性神经元数分别为150.2±10.3、223.0±11.6,SCG摘除组NOS阳性神经元数目较假手术对照组明显增加(P<0.05)。结论颈交感神经系统参与了头部血管源性疼痛(如偏头痛)中伤害性感觉信息导致的疼痛的产生、传导及调节过程。     

聚乙烯醇水凝胶髓核的生物力学特性

目的 对一种新型水凝胶人工髓核的生物力学特性进行研究,为将来临床开展人工髓核置换手术提供科学依据。方法 采用7具新鲜标本的L_(4-5)脊柱功能单元进行生物力学实验,在轴向压缩、前屈后伸和左右侧弯等运动工况下,观察正常椎间盘、髓核摘除以及人工髓核植入3种状态下椎间盘高度、应变和位移的变化。结果 与正常椎间盘相比较,髓核摘除后椎间盘的高度和刚度降低,应变和位移加大(P<0.05)。而人工髓核植入后各项指标恢复正常(P>0.05)。结论 这种新型水凝胶人工髓核置换可纠正髓核摘除后的生物力学紊乱,有望进行临床应用。     

不同时辰刺激大鼠的交叉上核对血浆中皮质酮含量的影响

应用拉丁方设计，在不同体重组的大鼠，于不同时辰，对交叉上核采取不同强度的刺激，用放射免疫法测定外周血中皮质酮的含量。其结果显示：各体重组间无显著性差异，不同时辰血浆皮质酮的平均含量各组呈现基本相同的节律性变化，无论何时辰刺激交叉上核使之兴奋，均可显著提高血浆皮质酮的含量。完全损毁交叉上核后７２小时血浆皮质酮含量和正常对照组无显著性差异，且其节律性也没有出现明显变化。     

Subcellular localization of the inositol 1,4,5-triphosphate receptor, P400, in the vestibular complex and dorsal cochlear nucleus of the rat

The subcellular localization of the inositol 1,4,5-trisphosphate receptor protein, P₄₀₀, was studied in the vestibular complex, an area to which Purkinje cells project, as well as in neurons of the dorsal cochlear nucleus and in ectopic Purkinje cells of adult rat brain. The receptor was demonstrated by electron microscopical immunocytochemistry using the avidin-biotin peroxidase complex procedure, with the monoclonal antibody 4C11 raised against mouse cerebellar inositol 1,4,5-trisphosphate receptor protein. Immunoreactivity was found in preterminal fibres and terminal boutons in the nuclei of the vestibular complex, generally associated with the subsurface systems and stacks or fragments of smooth endoplasmic reticulum. Ectopic Purkinje cells and cartwheel cells of the dorsal cochlear nucleus also displayed immunoreactivity, but this was much less intense in the latter. The results of the present study suggest that this receptor protein, involved in the release of Ca²⁺, is located in sites that enable it to influence the synthesis, transport and release of neurotransmitters.     

丘脑底核高频电刺激对大鼠纹状体多巴胺代谢影响的研究

目的研究丘脑底核(STN)高频电刺激(HFS)对大鼠纹状体多巴胺(DA)代谢的影响。方法给予正常大鼠一侧STN-HFS,应用微透析观察其对纹状体DA及其代谢产物的影响,应用免疫组化观察其对黑质DA能神经元的影响。结果微透析检测发现刺激侧纹状体DA代谢产物明显增高(P<0.05),DA水平无变化(P>0.05);免疫组化检测发现刺激组和对照组酪氨酸羟化酶(TH)阳性神经元数量无差异(损毁侧分别为24.00±6.81、23.43±5.49,P>0.05)。结论STN-HFS可能通过影响黑质-纹状体DA代谢发挥作用,STN-HFS对黑质DA能神经元可能无保护作用。     

多巴胺对正常和吗啡成瘾大鼠疼痛相关电活动的不同作用(英文)

目的研究多巴胺对正常大鼠和吗啡成瘾大鼠中枢的伤害性刺激的传递的影响。方法在给予坐骨神经伤害性刺激后,记录中枢痛兴奋神经元的电活动,观察多巴胺对正常大鼠和吗啡成瘾大鼠中枢痛兴奋神经元电活动的影响。结果正常大鼠中,多巴胺使尾核痛兴奋神经元的痛诱发放电潜伏期缩短,说明多巴胺可使正常大鼠尾核痛兴奋神经元的活动增强,多巴胺受体拮抗剂氟哌利多可以阻断这种作用。吗啡大鼠中,多巴胺使尾核痛兴奋神经元的痛诱发放电潜伏期延长,说明多巴胺可使吗啡大鼠尾核痛兴奋神经元的活动减弱。结论脑室注射多巴胺后,正常大鼠和吗啡成瘾大鼠的尾核对痛刺激的反应存在着差异。