大鼠三叉神经本体感觉中枢通路二、三级核团内Parvalbumin样阳性神经元突触联系的电镜研究

本教研室以往的研究证实 Parvalbum in样免疫阳性细胞广泛分布于三叉神经本体感觉中枢四级通路的各级中继核团 ,其中有 30 %～ 5 0 %为投射神经元。本研究应用电镜免疫组织化学技术进一步对此通路第二、三级神经元所在地的 Parvalbumin样阳性神经元及其纤维和终末的突触联系进行了观察。结果显示 Parvalbum in样阳性结构主要形成以下几种突触联系 :( 1) Par-valbumin样阳性轴突与 Parvalbumin样阳性胞体或树突形成轴 -体或轴 -树突触 ,其中以非对称性突触为主 ,对称性突触较少 ;( 2 )Parvalbumin样阳性轴突分别与 Parvalbumin样阴性神经元的胞体或树突形成轴 -体或轴 -树突触 ,这些突触联系以对称性为主 ,非对称性大约占 30 %左右 ;( 3) Parvalbumin样阴性终末与 Parvalbumin样阳性树突形成以对称性为主的轴 -树突触 ,这种突触大约占所有突触联系的 5 0 %。以上结果表明 :面口部本体感觉信息由三叉神经中脑核神经元向丘脑腹后内侧核传递的过程中 ,Par-valbumin样阳性轴突终末可通过突触传导机制而兴奋或抑制二、三级核团内的投射或中间神经元而发挥其重要作用     

GABA-like immunoreactivity in the cochlea of the developing mouse

Summary GABA-like immunoreactivity was studied in surface preparations of cochleas from postnatal developing mice, and GAD-like immunoreactivity was studied in the adult. GABA-positive fibres are already present at birth; they innervate both the inner and outer hair cells and some spiral ganglion cells. The GABA-positive fibres that enter via the intraganglionic bundle send collaterals to the spiral ganglion and to the hair cell region. Fibres that enter along the central processes of spiral neurons end predominantly among the spiral ganglion cells. A few spiral neurons display pericellular rings of GABA-positive boutons at birth. In older animals, the endings occur on a small number of spiral ganglion cells either as rings or as brush formations. The early GABA-positive fibres reach the inner hair cells around the second day and the outer hair cells (of the upper turns only) around the seventh day. In 12-day animals, tunnel fibres arborize in the outer hair cell region; their collaterals make contacts with the outer hair cells within four to eight cell-wide segments, distributing the endings high, up to the reticular plate. In older animals, fibres (both GABA- and GAD-positive) may innervate single vertical rows of outer hair cells. In the maturing and the adult cochlea, the GABA-positive component of the inner spiral bundle is conspicuous and extends along the entire cochlear length, but the innervation of the outer hair cells comprises only the mid and apical turns.GABA-positive nerve cells occur among the small vestibular neurons, occasionally among the cells of eighth nerve nucleus and only exceptionally in the spiral ganglion. In the adult animal, GAD-positive cells, although uncommon, were observed among the spiral neurons.In the developing animal, GABA-positive fibres give rise to transitory formations: (1) a convoluted plexus running beneath and among the radial bundles and (2) a sparse plexus, continuous with the inner spiral bundle and running in the upper plane of the inner spiral sulcus. GABA-like immunoreactivity was also observed in neuronal growth cones and in some fibres running along blood vessels.In conclusion, GABA immunoreactive fibres appear to reach the cochlea by two routes: via the intraganglionic bundle and to a much lesser extent via the central bundles of the spiral ganglion. The fibres innervate sensory cells and also some spiral neurons. The occasional presence of GABA-positive neurons in the vestibular ganglion, in the VIIIth nerve nucleus, and exceptionally among the spiral neurons raises the possibility of a local GABAergic circuitry within the inner ear.     

GABA能神经元在大鼠、树运动皮层的分布及其电镜观察

选取进化上种风差异较大的两种动物大鼠和树　为研究材料，在光镜和电镜下观察运动皮层的GABA能神经元．两种动物运动皮层中GABA能神经元的数量、大小及所占的比例都有明显的差异．大鼠运动皮层中GABA能种经元的平均密度为140．0±49．2个／mm2，树　则为214．0±82．9个／mm2，树　的密度明显高于大鼠．大鼠从Ⅱ层到Ⅵ层GABA能神经元的数量逐层降低，而树　从Ⅱ层到Ⅴ层逐层降低，Ⅵ层的密度则高于Ⅴ层，二者密度最高的都是在Ⅱ层．大鼠GABA能神经元的最长在平均为14．2±1．2μm，树　为11．9±1．6μm．大鼠最长径在15μm以上的占29．8％；而树　仅占11．3％，树　的GABA能神经元比大鼠的要小．所以在进化较高等的动物－树　的运动皮层中，GABA能神经元的密度较高，大的GABA能神经元较少．电镜观察显示GABA能神经元表面既接受对称型突触又接受非对称型突触，两种动物非对称型突触的数目都不与GABA能神经元的周长及截面积呈线性相关．对称型突触既有GABA能的也有非GABA能的；大鼠GABA能的及非GABA能的对称型突触，和树　非GABA能的对称型突触都与GABA能神经元的周长及截面积呈线性关系．     

下丘脑弓状核内GABA神经元与P物质神经元相互关系的免疫电镜双标研究

为了探讨下丘脑神经内分泌功能的突触调控机制和Ｐ物质（ＳＰ）神经元与γ－氨基丁酸（ＧＡＢＡ）神经元之间的相互关系，我们用包埋前免疫电镜ＰＡＰ双标技术，研究了大鼠弓状核内ＳＰ和ＧＡＢＡ神经元的超微结构分布。先以ＤＡＢ为呈色剂显示ＳＰ的免疫反应，然后用钢酸铵－ＴＭＢ法显示ＧＡＢＡ免疫反应，再经ＤＡＢ－氧化钴稳定后作免疫电镜研究。结果观察到，在弓状核内有大量含ＤＡＢ和ＴＭＢ免疫反应产物的神经元结构，ＤＡＢ反应产物为颗粒状或絮状沉淀，电子密度高，弥漫分布；ＴＭＢ反应产物呈针状或块状，散在分布。含ＤＡＢ免疫反应的结构有ＳＰ神经元的胞体、树突和轴突。含ＴＭＢ免疫反应的结构有ＧＡＢＡ神经元的胞体、树突和轴突。两种神经元均为中、小型细胞，在弓状核内混杂分布。含ＳＰ的轴突接受免疫反应阴性轴突的非对称性突触连接；含ＳＰ的树突与含ＧＡＢＡ的轴突形成对称性的轴一树突触。含ＧＡＢＡ的树突接受免疫反应用性轴突的非对称性突触连接，也接受含ＳＰ轴突的非对称性突触连接。本研究不仅在超微水平进一步证实了大鼠弓状核内存在着ＳＰ和ＧＡＢＡ神经元及其末梢，而且首次在形态学上为下丘脑氨基酸能神经元与肽能神经元之间的相互调控提供了超微结构依据。     

Anterograde tracer study on the nucleus geniculatus dorsalis and its internal synaptic structure in chick brain

In the present study the terminals of retinal fibres and those of internal layer cells in ventral geniculate nucleus of chicks were labelled with the anterograde tracer biotinylated dextran amine. The tracer showed the connections from the internal cell layers of ventral geniculate nucleus to the medial part of the dorsal lateral geniculate nucleus. The labelled retinal terminals were located exactly in the lateral part of nucleus. The labelled terminals in the two parts of the nucleus were analysed with the electron microscope and showed a different synaptic organisation in the two parts of the dorsal lateral geniculate nucleus. In the lateral part, two kinds of synaptic glomeruli were found mostly in the vicinity of large dendrites, which are proximal dendrites of projection neurons. One type is a simple glomerulus containing a large dendrite, a large optic terminal and a large and/or series of asymmetrical synapses surrounded by glial processes. The other type is a complex synaptic unit with several pre- and postsynaptic components, among them synapses of GABA-positive axon terminals and/or dendraxons. No glomeruli were found in the medial part of the nucleus. In the medial part of the lateral geniculate nucleus, the terminals of internal layer cell axons established asymmetrical synapses with dendrites. Often, a large terminals and large dendritic profiles established serial asymmetrical synapses. GABA-positive myelinated fibres entered and ramified in both parts of the dorsal lateral geniculate nucleus, and GABA-positive terminals were seen to form synapses on the same dendrite near to the asymmetrical contacts. To our knowledge, this is the first report of the connection from ventral geniculate internal layer cells to the dorsal lateral geniculate nucleus in the chick.     

Presence of neurons with GABA-like immunoreactivity in the superior cervical ganglion of the rat

Using antibodies raised against gamma-aminobutyric acid (GABA)-glutaraldehyde complexes, we have found neurons with GABA-like immunoreactivity in the superior cervical ganglion of adult rats. The processes of these neurons formed pericellular networks around the principal ganglion cells. Electron microscopy revealed that the immunoreactive dendrites were innervated by non-reactive axon terminals which formed asymmetrical synapses and probably originated from the preganglionic nerve. Axons with GABA-like immunoreactivity, especially axonal varicosities filled with synaptic vesicles, were found in direct apposition to principal ganglion cells. The GABA-positive axons and axon varicosities persisted in experimentally decentralized (deafferented) ganglia, suggesting that the perikarya of the immunoreactive neurons were intrinsic to the superior cervical ganglion. Taken together with data on inhibitory effects of GABA in sympathetic ganglia, these findings suggest that the superior cervical ganglion of rats contains a subpopulation of inhibitory interneurons which is GABAergic. This would indicate that GABAergic neurons do not only occur in the central but also in the peripheral nervous system.     

Ultrastructural study of cholecystokinin-like immunoreactive nerve terminals in the rat nucleus accumbens

The cholecystokinin (CCK)-like immunoreactive nerve terminals were studied in the caudal and medial parts of the rat nucleus accumbens (NA), using the indirect immunoperoxidase technique, at the electron microscopic level. In the labelled axon terminals the immunoprecipitate is localized inside large dense-cored vesicles which are occasionally present, and surrounds small and medium-sized, round, clear synaptic vesicles. The immunoreactive nerve terminals participate in synapses of both asymmetrical and symmetrical types containing mostly small synaptic vesicles. The asymmetrical synapses are much more numerous and mainly axo-spinous. The symmetrical synapses are less frequent and are axo-dendritic or axo-somatic.     

Synaptic connections of enkephalin-immunoreactive nerve terminals in the neostriatum: a correlated light and electron microscopic study

Summary Two different antisera to leucine-enkephalin were used to study the localization of enkephalin-like immunoreactive material in the neostriatum and globus pallidus of the rat, by means of the unlabelled antibody-enzyme method. Thin immunoreactive varicose fibres are scattered throughout the neostriatum. In the ventral striatum, fibres come together and follow a relatively straight course for several micrometers, forming tube-like structures which can be traced to cell bodies; these cell bodies are completely surrounded by immunoreactive fibres. Occasional immunoreactive varicose fibres are also found close to another type of neuron throughout the whole neostriatum.Examination by electron microscopy of immunoreactive structures that had been identified first in the light microscope, showed that each of the nearly 200 varicosities examined was a vesicle-containing bouton that formed a synaptic contact. Rarely were asymmetrical synaptic contacts found between immunoreactive boutons and dendritic spines. All other synapses formed by enkephalin-immunoreactive boutons were symmetrical. Two types of postsynaptic neuron were identified; the first type was a medium-sized neuron with the ultrastructural features of a typical striatal spiny neuron. The second type had a larger perikaryon surrounded by numerous immunoreactive varicosities that were found to be boutons forming symmetrical synapses. The long dendrites of this second type of neuron likewise received a dense input of immunoreactive boutons forming symmetrical synapses; such ensheathed dendrites were found to be the tube-like structures seen in the light microscope. The ultrastructural features of these neurons, notably a highly indented nucleus, were those of a rare type of striatonigral neuron. In the globus pallidus, all the enkaphalin-immunoreactive boutons studied formed symmetrical synapses with ensheathed dendrites and perikarya that were similar to the latter type of postsynaptic neuron in the neostriatum. Axo-axonic synapses involving immunoreactive boutons were not seen in our material.The results are consistent with the view that enkephalin-like substances may be synaptic transmitters in the neostriatum and that they may have different actions according to the nature of the postsynaptic target. The finding that one type of neostriatal neuron, and a very similar neuron in the globus pallidus, receives multiple enkephalin-immunoreactive boutons all over its perikaryon and along its dendrites indicates a potentially important role of enkephalin in the convergence of information within the neostriatum and pallidum on to output neurons.     

Synaptic contacts between serotonergic and cholinergic neurons in the rat dorsal raphe nucleus and laterodorsal tegmental nucleus

We examined synaptic connectivity between cholinergic and serotonergic neurons in the dorsal raphe nucleus and the laterodorsal tegmental nucleus of the rat. To this purpose we employed two variations (the combination of pre-embedding immunogold-silver intensification with avidin-biotin-peroxidase complex technique and the combination of avidin-biotin-peroxidase/3, 3'-diaminobenzidine/silver-gold intensification with avidin-biotin-peroxidase/3,3'-diaminobenzidine reaction) of a double pre-embedding immunoelectron procedure, using primary antibodies against vesicular acetylcholine transporter and serotonin. At the light-microscopic level, serotonin-like immunoreactive neurons in the dorsal raphe nucleus appeared as reddish black and vesicular acetylcholine transporter-like immunoreactive axon terminals were brown colored using a combination of pre-embedding immunogold-silver technique and avidin-biotin-peroxidase complex technique. Serotonin-like immunoreactive fibers projected to the laterodorsal tegmental nucleus. At the electron microscopy level, with both methods we observed in the dorsal raphe nucleus vesicular acetylcholine transporter-immunopositive axon terminals in synaptic contact with serotonin-like immunoreactive dendrites and, to a lesser degree, with serotonin-like immunoreactive cell bodies. These synapses usually were of the symmetrical type. Occasionally we noted, next to vesicular acetylcholine transporter-immunopositive axon terminals, also immunonegative terminals synapsing with the serotonin-like immunoreactive dendrites. In the laterodorsal tegmental nucleus we found serotonin-like immunoreactive axon terminals and immunonegative terminals forming synapses with vesicular acetylcholine transporter-immunoreactive dendrites. Most synapses formed by the serotonin-like immunopositive terminals were of the asymmetrical type.Our results suggest that serotonergic neurons in the dorsal raphe nucleus and cholinergic neurons in the laterodorsal tegmental nucleus may reciprocally influence each other by means of synaptic connectivity. Such connectivity may serve to regulate pain sensation, or be involved in the regulation of the sleeping-waking cycle.     

A quantitative ultrastructural analysis of neurotensin-like immunoreactive terminals in the midbrain periaqueductal gray: analysis of their possible relationship to periaqueductal gray-raphe magnus projection neurons

The periaqueductal gray of the rat contains significant levels of the putative peptide neurotransmitter neurotensin. The profound anti-nociceptive effects of neurotensin injected into the periaqueductal gray may involve a population of periaqueductal gray neurons having descending projections to the rostral ventral medulla, including nucleus raphe magnus and adjacent reticular nuclei. In this study, electron microscopic immunocytochemistry was used to examine the ultrastructure of periaqueductal gray axon terminals containing neurotensin-like immunoreactive material and to obtain quantitative data regarding the relationship of such terminals to other elements of the neuropil. Of particular interest was the interaction between neurotensin-like immunoreactive terminals and retrogradely labeled neurons that project to nucleus raphe magnus and adjacent reticular nuclei. Within the periaqueductal gray, the sites of retrograde and immuno-labeling were consistent with previous reports. The neurotensin-immunoreactive structures were predominantly axon fibers and terminals. In the ventrocaudal periaqueductal gray, the mean diameter of neurotensin-containing terminals was 0.93 +/- 0.02 micron and they comprised a volume fraction of 0.0010. Most of the neurotensin-positive terminals examined (74.2%) were in contact with or closely apposed to dendrites. The most common anatomical configuration observed was a single neurotensin-immunoreactive terminal juxtaposed to three dendrites. Only 2% of immunoreactive terminals were apposed to perikarya. Neurotensin-immunoreactive terminals were observed to form symmetrical synapses and 96.4% of such terminals were axodendritic. Occasional multiple neurotensin-immunoreactive terminals associated with single dendrites were observed. Although neurotensin-like immunoreactive terminals were quite prominent, only a small percentage made synaptic contact with periaqueductal gray neurons that project to the nucleus raphe magnus and adjacent reticular formation. Among the population of periaqueductal gray neurons retrogradely-labeled from nucleus raphe magnus and adjacent reticular nuclei, the frequency of direct synaptic contact by neurotensin-immunoreactive terminals was 2%. These data suggest that the periaqueductal gray circuitry by which neurotensin ultimately affects descending pathways is complex and may involve a population of local circuit neurons whose transmitters and connections remain to be elucidated.     

An immunocytochemical mapping of ACTH/CLIP in the cat diencephalon

Using an indirect immunoperoxidase technique, the location of cell bodies and fibres containing adrenocorticotropin hormone/corticotropin-like intermediate lobe peptide (ACTH/CLIP) was studied in the cat diencephalon. Immunoreactivity was observed in several diencephalic nuclei of the cat in which no immunoreactivity has been previously reported. In this sense, a low density of immunoreactive cell bodies was found in the nucleus ventromedialis hypothalami; a high density of immunoreactive fibres was found in the medial preoptic area; a moderate density in the lateral preoptic area and in the nuclei centralis thalami (pars medialis), interventralis thalami, interanteromedialis thalami, parafascicularis and praemamillaris (pars ventralis and pars dorsalis); a low density in the nuclei habenularis lateralis and reuniens thalami, and single fibres were found in the nuclei lateralis thalami (pars anterior), habenularis medialis, parataenialis, corpus geniculatum mediale, ventralis thalami (pars medialis) and in the fornix. Our results point to a more widespread distribution of ACTH/CLIP immunoreactive structures in the cat diencephalon in comparison with previous studies carried out in the same region of this feline.     

Topographic localization of neuromedin U-like structures in the rat brain: an immunohistochemical study

The distribution of neuromedin Us, uterus-stimulating and hypertensive peptides newly identified in porcine spinal cord, was examined in the rat brain by the indirect immunofluorescent method. Neuromedin U-like immunoreactive structures were found to be unevenly distributed in the neuronal system. Neuromedin U-like immunoreactive neurons were present in the cranial motor nuclei, reticular nuclei, nucleus vestibularis lateralis, trigeminal sensory nuclei, colliculus superior and inferior, lemniscus lateralis, nucleus pontis, nucleus ruber, zona incerta, substantia innominata, horizontal limb of the diagonal band and cerebral cortex. The immunoreactive fibres were found in the above areas, particularly near the labelled cells, forming a fibre plexus with various intensities of immunoreactivity. In addition, dense plexuses were also seen in the nucleus reticularis thalami, nucleus ventralis posteromedialis, nucleus ventralis posterolateralis, nucleus tegmentalis dorsalis and ventralis, vertical limb of the diagonal band, nucleus olivaris superior, and nucleus pontis. In the first six structures, no labelled neurons were present and in the remaining structures, a few scattered neurons were noted. This indicates that these fibres are probably of extrinsic origin.     

迷走神经背核尾侧部内神经降压肽样免疫反应终末联系的电镜研究

用辣根过氧化物酶逆行标记法结合免疫细胞化学法(PAP法)对大鼠迷走神经背核尾侧部内神经降压肽样免疫反应终末的核内联系进行了电镜下的研究.发现少量神经降压肽样免疫反应轴突终末与HRP逆行标记的副交感节前神经元的树突构成非对称性突触;大多数神经降压肽样免疫反应轴突终末与未标记中间神经元的胞体和树突构成对称性或非对称性突触,以轴-树突触为主;未标记的轴突终末也可同HRP逆行标记的副交感节前神经元的胞体和树突构成对称性或非对称性突触.由此认为核内神经降压肽样免疫反应终末可通过直接或间接联系(后者为主)作用于副交感节前神经元,从而参与对内脏、心血管活动的调节.     

GABA and glycine as putative transmitters in subcortical pathways to the pontine nuclei. A combined immunocytochemical and retrograde tracing study in the cat with some observations in the rat.

Using the retrograde tracers horseradish peroxidase-wheatgerm agglutinin and gold particles conjugated to wheatgerm agglutinin apo-horseradish peroxidase in combination with an antiserum against glutaraldehyde-fixed GABA, it was examined whether the pontine nuclei of the cat receive projections from GABA-like immunoreactive neurons in the brainstem, diencephalon, or deep cerebellar nuclei, contributing to the GABA-like immunoreactive fibre plexus previously demonstrated in the pontine nuclei [Brodal et al. (1988) Neuroscience 25, 27-45]. Following tracer injections that covered both the pontine nuclei and the reticular tegmental nucleus in two cats, it was found that 125 out of 1166 (10.7%) and 29 out of 294 (9.9%) retrogradely labelled neurons in the cerebellar nuclei were GABA-like immunoreactive. In the same two experiments only six out of 2029 (0.3%) and 10 out of 1398 (0.7%) retrogradely labelled neurons in the brainstem and diencephalon were GABA-like immunoreactive. Among the regions in the brainstem and diencephalon known to project to the pontine nuclei, double-labelled cells were seen in the reticular formation, the periaqueductal gray, and the nucleus praepositus hypoglossi, but not in the zona incerta or the anterior pretectal nucleus, regions that have been shown to contain glutamate decarboxylase-like immunoreactive neurons projecting to the pontine nuclei in the rat [Border et al. (1986) Brain Res. Bull. 17, 169-179]. In order to test whether this is due to species differences, the same experimental approach was used in the rat, and it was found that 54 out of 3249 (1.7%) retrogradely labelled neurons in the brainstem and diencephalon were double-labelled. Notably, in the zona incerta 2% of the retrogradely labelled cells were also GABA-like immunoreactive, and in the reticular formation there was a higher proportion of double-labelled cells than was found in the cat. Additional sources were identified, that may contribute to the GABA-like immunoreactive fibre plexus in the pontine nuclei of the rat. This, in conjunction with the previous finding that the pontine nuclei of the rat contain only very few putative GABAergic neurons [Border and Mihailoff (1985) Expl Brain Res. 59, 600-614; Brodal et al. (1988) Neuroscience 25, 27-45], lead to the suggestion that the GABA-like immunoreactive fibre plexus in the pontine nuclei of the rat is predominantly of extrinsic origin, possibly representing a mosaic of the terminal fields of several subcorticopontine projections.(ABSTRACT TRUNCATED AT 400 WORDS)     

Distribution of GABA-immunoreactive neurons in the thalamus of the squirrel monkey (Saimiri sciureus)

A light microscopic study of the cellular localization of GABA in the thalamus of the squirrel monkey (Saimiri sciureus) was undertaken by means of the indirect peroxidase-antiperoxidase method using a highly purified antiserum directed against GABA-glutaraldehyde-lysyl-protein conjugate. GABA-immunoreactive cell bodies and axon terminals were visualized in all thalamic nuclei in the squirrel monkey but their relative density varied from one nucleus to the other. At the level of the anterior nuclear group, GABA-positive cells and terminals abounded in the anterodorsal nucleus but were much less numerous in the anteromedial and anteroventral nuclei. In the nuclei of the ventral group, GABA-immunoreactive cells were found to be smaller and less numerous than nonimmunoreactive neurons. In the ventral anterior nucleus, GABA-positive neuronal profiles formed typical clusters, whereas they were more uniformly distributed in the posterior nuclei of the ventral group. In the intralaminar nuclei, GABA-immunoreactive cells and terminals abounded in the dorsal portion of the paracentral and centrolateral nuclei, whereas more caudally, GABA-positive terminals pervaded the entire parafascicular nucleus. In the mediodorsal nucleus, GABA-positive cell bodies and axon terminals formed typical clusters of various sizes scattered within the lateral parvocellular portion of the nucleus, while GABA-immunoreactive neuronal profiles were less numerous and more uniformly distributed in the medial portion of this structure. In the nuclei of the posterior group, GABA-immunoreactive neuronal profiles were uniformly distributed except in the pulvinar where they abounded in the inferior and oral parts but were scarce in the medial part. In the dorsal lateral geniculate nucleus, the magnocellular layers received the most massive GABA-positive innervation and contained the largest number of GABA-immunoreactive cell bodies. In the ventral lateral geniculate nucleus, GABA-positive cells occurred only ventrolaterally while GABA-immunoreactive terminals pervaded the entire structure. In the medial geniculate nucleus, GABA-immunoreactive cell bodies and terminals abounded particularly within the ventromedial third of the structure. In the habenula, a few GABA-immunoreactive cell bodies and numerous GABA-positive terminals were scattered throughout the lateral habenular nucleus, whereas only a few GABA-immunoreactive terminals surrounded the closely packed unreactive cells in the medial habenular nucleus. In contrast to other thalamic nuclei all neurons in the reticular nucleus displayed GABA immunoreactivity.(ABSTRACT TRUNCATED AT 400 WORDS)     

大鼠外侧膝状体背核的主要突触构筑

外侧膝状体背核(DLG)的突触构成成份主要来自视网膜、视皮质、丘脑网状核的轴突终末和DLG内神经元的突起。视网膜和视皮质来的轴突终末对DLG投射神经元和中间神经元的树突形成非对称性突触,丘脑网状核的轴突终末则对这两类神经元构成对称性突触,而中间神经元树突具有轴突样作用,对投射神经元树突形成对称性突触。这些结果有助于我们了解视觉信息在DLG内的加工处理过程。     

中央杏仁核内CGRP能阳性突触的超微结构研究

目的:观察降钙素基因相关肽(calcitonin-gene-related peptide,CGRP)样阳性终末在中央杏仁核(cen-tral nucleus of amygdala,CeA)内形成的突触的超微结构。方法:应用免疫荧光组织化学和包埋前免疫电镜等方法,观察CGRP样阳性终末在CeA内所形成的突触分布形式及结构特点。结果:CGRP样阳性终末在中央杏仁核内可以与细胞体、树突干和树突棘等结构形成突触;轴-体突触几乎全为对称性突触,而轴-树突触和轴-棘突触则多为非对称性突触。在所有的非对称性突触里,轴-树突触占84.9%,而轴-棘突触占15.1%。CGRP样阳性轴-树的突触后致密带的平均长度为(790.77±313.55)nm,而轴-棘突触的突触后致密带的平均长度为(723.34±357.20)nm,两者之间没有显著性差异。结论:CGPR样阳性的兴奋性突触尤其是轴-树突触在伤害性信息传递以及痛相关情绪的产生中发挥了重要作用。     

A GABAergic projection from the central nucleus of the amygdala to the parabrachial nucleus: an ultrastructural study of anterograde tracing in combination with post-embedding immunocytochemistry in the rat

To determine whether axonal terminals emanating from the central nucleus of amygdala (Ce) to the parabrachial nucleus (PBN) contain gamma-aminobutyric acid (GABA) as their neurotransmitter, an electron microscopic study was performed employing the combined techniques of WGA-HRP anterograde tracing and post-embedding immunocytochemistry for GABA. Our analysis distinguished a large population of GABA immunopositive axonal terminals from the Ce that exhibited symmetrical synaptic contacts with neurons in the lateral parabrachial nucleus. Additionally, most retrogradely labeled dendrites and perikarya received synaptic contacts from GABA immunoreactive terminals, with some of them originating from the Ce. The present study provides the first direct ultrastructural evidence for a monosynaptic, GABAergic link between Ce axons and neurons of the parabrachial nucleus via classical symmetrical synapses.