猫丘脑中央外侧核内丘脑皮质投射神经元的超微结构及其突触联系

应用ＨＲＰ逆行追踪法在电镜水平上对猫丘脑中央外侧核内皮质投射神经元的超微结构及其突触联系首次进行了研究。该核内皮质投射神经元以中型多见，胞核较大，核仁清晰，偏位，核膜有凹陷，常染色质较多，胞质内含丰富的线粒体，游离核糖体和粗面内质网。标记树突直径变化较大，从０．６８μｍ到４．４μｍ，含较多的线粒体、微管及滑面内质网，凶突触小泡。标记的皮质投射神经元胞体和树突做为突触后成分，与非标记的突触前成分形成     

猫丘脑腹后外侧核内皮质—丘脑纤维终末与丘脑—皮质投射神经元…

用ＣＢ－ＨＲＰ逆行追踪与顺行溃变相结合的方法，对猫丘脑腹后外侧核内的来自大脑皮质体感Ｉ区的皮质－丘脑纤维终末与丘脑－皮质投射神经元之间的突触连接进行了电镜观察。向猫大脑皮质体感Ｉ区内注射ＣＢ－ＨＲＰ５ｈ后，电解损毁原注射部位，术后动物存活４ｄ。电镜下发现丘脑腹后外侧核内存在５种突触连接方式：（１）溃变的轴突终末与ＨＲＰ标记神经元胞体形成轴－体突触；（２）溃变的轴突终末与ＨＲＰ标记的树突形成轴－树突     

心肌缺血大鼠丘脑束旁核神经元放电频率的变化

当前大部分关于疼痛机制的信息是从躯体痛的研究得来的,有关心绞痛的临床和实验室资料非常有限。Rosen等（1994）的研究提示丘脑可能在心肌缺血性疼痛过程中起非常重要的作用。然而,大鼠丘脑束旁核（nucleus parafaseieularis of thalamus,Pf）在缺血性心绞痛过程中究竟发挥怎样的作用,文献一直没有报道。     

皮质丘脑投射神经元的超微结构及突触联系

采用ＨＲＰ逆行追踪技术与电镜相结合的方法，对猫大脑皮质体感Ⅰ区内皮质丘脑投射神经元超微结构及突触联系进行了研究。结果证明，皮质丘脑投射神经元超微结构的特点为锥体形的胞体，胞浆丰富，含有多量的粗面内质网，游离核糖体及线粒体。ＨＲＰ标记的皮质丘脑投射神经元作为突触后成份与轴突和树突分别形成轴－树突触，轴－体突触和树－体实触。这些结果提示：皮质丘脑投射神经元接受广泛的传入联系和皮质间的联系。     

大鼠纹状体parvalbumin阳性中间神经元的超微结构

目的:研究纹状体parvalbumin (Parv)阳性中间神经元在神经通路上的突触连接.方法:利用免疫组织化学和神经示踪方法标记SD大鼠纹状体Parv及其相关神经元,光镜和电镜观察阳性神经元的结构和位置关系.结果:Parv阳性中间神经元中等大小,散在分布于纹状体,以背外侧居多.光镜免疫双标记显示Parv阳性中间神经元与皮质、丘脑和中脑黑质的传入轴突终末形成明显的形态位置上的邻近关系,其轴突终末则与纹状体不同类型投射神经元在光镜下也形成邻近关系.Parv阳性中间神经元的免疫电镜观察显示阳性产物主要游离于胞体、树突和轴突的胞质内.Parv阳性中间神经元的胞体和树突均接受大量的非对称型突触传入.Parv阳性轴突终末平均大小为(0.62±0.28)μm,可见其与纹状体神经元的树突、胞体和树突棘形成对称型突触,其中与树突形成的突触占69.64%,与胞体和树突棘形成的突触分别为26.78%和3.58%.结论:纹状体Parv阳性中间神经元形态学上与皮质、丘脑、黑质以及纹状体投射神经元形成突触连接,提示其可能在调节纹状体信息传入和输出过程中具有重要作用.     

猫丘脑中央外侧核内脊丘系终末与丘脑—皮质投射神经元之间的…

本实验应用顺行溃变和ＨＲＰ逆行追踪相结合的方法。首次在是水平对猫丘脑外侧核内脊丘系终末与丘脑－皮质投射神经元的突触联系进行了研究。     

猫丘脑中央外侧核内脊丘系终末与丘脑-皮质投射神经元之间的突触联系

本实验应用顺行溃变和HRP逆行追踪相结合的方法，首次在电镜水平对猫丘脑中央外侧核内脊丘系终末与丘脑-皮质投射神经元之间的突触联系进行了研究．在脊髓第4颈段刀切损毁一侧侧索和前索后，将HRP注射于同侧大脑前上薛氏回和中上薛氏回前端。在电镜下于损毁同侧中央外侧核内可见下列突触连结：（1）溃变的脊丘系轴突终末与标记树突形成的轴-树突触；（2）溃变的脊丘系轴突终末与非标记树突形成的轴-树突触，个别非标记树突含有突触小泡；（3）正常的轴突终末与HRP标记树突和胞体形成的轴-树突触和轮一体突触；（4）正常的两个轴突终末与HRP标记树突形成的轴-轴-树连续性突触；（5）非标记的含突触小泡的突触前树突与HRP标记树突形成的树-树突触。同时可见大量汇聚型突触复合体。本文首次报道在丘脑中央外侧核内，脊丘系终末与丘脑-皮质投射神经元之间存在着直接的突触联系。     

猫丘脑中央外侧核内丘脑皮质投射神经元的形态与分布

应用ＨＲＰ逆行追踪法在光镜水平研究了猫丘脑中央外侧核向前乙状回，前上薛氏回前端揣射的神经元的形态与分布。结果表明：中央外侧核向大脑皮质的投身为同侧投射，中央外侧核向前乙状回投射的神经元集中于核的尾段，少部分位于中段，偏内侧分布，大中，小，型投射神经元均有，以中，小型为主。     

猫颈外侧核内颈丘脑投射神经元的超微结构及其突触联系

猫颈外侧核接受来自同侧脊髓后角的脊颈束 ,其传出纤维投射至对侧的丘脑腹后外侧核。该通路与传导皮肤的伤害性信息有关。本文采用 HRP逆行追踪技术 ,在电镜水平研究了猫颈外侧核内颈丘脑投射神经元的超微结构及其突触联系。将 HRP注入猫左侧丘脑腹后外侧核 ,经颈总动脉灌流固定 ,TMB法呈色反应。选取右侧颈外侧核内有 HRP标记的细胞制备电镜标本 ,透射电镜观察。结果发现 ,颈外侧核内出现大、中型 HRP标记神经元 ,细胞核为卵圆形 ,可见核仁 ,胞浆丰富 ,含有多量的线粒体等细胞内器 ,HRP反应产物散在于其中。在颈丘脑投射神经元胞体的周围见有 HRP标记的树突以及非标记的轴突、神经元胞体及树突。 HRP标记的颈丘脑投射神经元作为突触后成分与其他成分形成轴 -树突触 ,轴 -体突触 ,轴 -轴 -体突触及轴 -树突触复合体。这些结果提示 :颈丘脑投射神经元接受广泛的传入联系     

前庭神经核纤维与投射至纹状体的束旁核神经元的突触联系

目的：观察发自前庭神经内侧核的纤维末梢与投射至纹状体的丘脑束旁核神经元的突触联系。方法：采用15只Wistar大鼠,应用顺行和逆行标记技术,免疫组织化学和免疫电镜方法。结果：将CTb单侧注入纹状体,同时将BDA注入同侧的前庭神经内侧核。在束旁核发现了CTb标记神经元和BDA标记轴突终末,BDA标记纤维和终末存在于外侧束旁核整个长度的背侧2／3区,而CTb标记神经元也存在于外侧束旁核背侧2／3区,2种标记相互重叠。电镜下可见标记终末与标记神经元形成非对称性的轴-体和轴-树突触。结论：由前庭神经内侧核发出的投射纤维在束旁核与投射至纹状体的束旁核神经元之间存在着非对称性的突触联系。     

Apomorphine-induced ipsilateral turning in rats with unilateral lesions of the parafascicular nucleus

Summary Apomorphine, 2 mg/kg i.p., produced ipsilateral turning in rats with unilateral lesions in the parafascicular nucleus of the thalamus. The effect was completely blocked by the administration of haloperidol, 0.3 mg/kg i.p. There were no asymmetries by the lesions alone or after administration of haloperidol, 2 mg/kg i.p. to lesioned animals. In control experiments apomorphine produced a marked contralateral turning in animals with unilateral degeneration of the fasciculus retroflexus.Supported by the Swedish Humanities and Social Sciences Research Council (F203/79), The Swedish Medical Research Council (14X-502), Magnus Bergvall Foundation, Albert Nilsson Foundation, and Anna Ahrenbergs Foundation     

Enhanced suppression of a conditioned avoidance response by haloperidol but not phenoxybenzamine in rats with bilateral parafascicular lesions

Summary Male rats were subject to bilateral lesions in the parafascicular nucleus (PF) of the thalamus. The lesions had little or no effect on the performance of a pre-operatively acquired conditioned avoidance response. However, the PF lesioned animals displayed an enhanced response to the dopamine receptor blocking agents haloperidol or pimozide but not to the noradrenaline receptor blocking agent phenoxybenzamine. The results indicate that intralaminar thalamic nuclei and dopaminergic extrapyramidal motor pathways are functionally connected.     

In situ hybridization histochemical and immunohistochemical evidence that striatal projection neurons co-containing substance P and enkephalin are overrepresented in the striosomal compartment of striatum in rats

In a prior study, we showed that the few striatal projection neurons that contain both substance P (SP) and enkephalin (ENK) in rats may preferentially project to the substantia nigra pars compacta. Since striatal neurons that project to the pars compacta are thought to preferentially reside in the striosomal compartment, we investigated if striatal neurons that contain both SP and ENK are preferentially localized to the patch compartment. We used in situ hybridization histochemistry to double-label sections for SP and ENK to identify SP/ENK co-containing neurons, and immunolabeling of adjacent sections for the mu opiate receptor (MOR) to define the striosomal compartment. We found that 32.3% of neurons containing both SP and ENK were localized to the striosomal compartment, which itself only made up 12.8% of the striatum. Our results further showed that the density of neurons co-containing SP and ENK was three-fold higher in striosomes than in the matrix compartment. These results are consistent with the notion that SP/ENK colocalizing neurons preferentially project to pars compacta, and these and our prior results additionally raise the possibility that neurons of this type in the striatal matrix may also project to the pars compacta.     

高脂血症大鼠弓状核超微结构及神经肽Y神经元的变化

目的:观察高脂血症大鼠弓状核超微结构及神经肽Y(neuropeptide Y,NPY)免疫阳性神经元的变化。方法:实验组大鼠高脂饲料饲养6周测血脂,透射电镜观察弓状核超微结构,免疫组化染色观察测量NPY免疫阳性神经元光密度、数量及截面积。结果:实验组血清总胆固醇及低密度脂蛋白胆固醇明显升高;弓状核超微结构出现明显病理学改变。NPY神经元平均光密度、细胞数、截面积减少。结论:高脂血症可诱导弓状核神经元超微结构和NPY神经元改变,为进一步探讨血脂代谢异常与中枢神经的内分泌关系提供形态学依据。     

The interrelations between cell groups in the caudal diencephalon of the rat projecting to the striatum and to the medulla oblongata

Summary In order to investigate the topographical relationships between the caudal diencephalic cells of origin of ascending and descending projections in the rat, one fluorescent retrograde tracer was injected into the striatum and another into the medulla oblongata. The medullary injections were mainly centered in the inferior olive. Cells labeled from the striatal injections densely filled the thalamic parafascicular nucleus. Cells labeled from the medullary injections were seen ventrally to the fasciculus retroflexus in the subparafascicular nucleus. The two populations were mixed in a small area at the ventromedial border of the fasciculus retroflexus. No double labeled cells were observed. The present results indicate that caudal diencephalic cells which ascend to the striatum are different from those descending to the medulla oblongata and that they partially overlap.Supported in parts by CNR grants N. 80.00515-04, 81.00283.04     

Ascending projections of posterior canal-activated excitatory and inhibitory secondary vestibular neurons to the mesodiencephalon in cats

The axonal projections of 62 posterior canal (PC)-activated excitatory and inhibitory secondary vestibular neurons were studied electrophysiologically in cats. PC-related neurons were identified by monosynaptic activation elicited by electrical stimulation of the vestibular nerve and activation following nose-up rotation of the animal's head. Single excitatory and inhibitory neurons were identified by antidromic activation following electrical stimulation of the contralateral and ipsilateral medial longitudinal fasciculus, respectively. The oculomotor projections of identified neurons were confirmed with a spike-triggered averaging technique. The axonal projections of the identified neurons were then studied by systematic, antidromic stimulation of the mesodiencephalon. Excitatory neurons showed two main types of axonal projections. In one type, axonal branches were issued to the interstitial nucleus of Cajal, central gray, and thalamus including the ventral posterolateral, ventral posteromedial, ventral lateral, ventral medial, centromedian, central lateral, lateral posterior, and ventral lateral geniculate nuclei. The other type was more frequently observed, giving off axon collaterals to the above-mentioned regions and to Forel's field H as well. Inhibitory neurons issued axonal branches to limited areas which included the central gray, interstitial nucleus of Cajal, its adjacent reticular formation and caudalmost part of Forel's field H, but not the rostral part of the Forel's field H and the thalamus. These results suggest that PC-related excitatory neurons participate in the genesis of vertical eye movements and in the perception of the vestibular sensation, and that PC-related inhibitory neurons seem to take part only in the genesis of vertical eye movements.Deceased     

The vestibulothalamic projections in the cat studied by retrograde axonal transport of horseradish peroxidase

Summary Horseradish peroxidase (HRP) was injected or iontophoretically ejected in various thalamic nuclei in 63 adult cats. In 11 other animals HRP was deposited outside the thalamic territory. The number and distribution of labelled cells within the vestibular nuclear complex (VC) were mapped in each case. To a varying degree all subgroups of VC appear to contribute to the vestibulothalamic projections. Such fibres are distributed to several thalamic areas. From the present investigation it appears that generally speaking, there exist three distinct vestibulothalamic pathways with regard to origin as well as to site of termination of the fibres. One projection appears to originate mainly in caudal parts of the medial (M) and descending (D) vestibular nuclei and in cell group z. This pathway terminates chiefly in the contralateral medial part of the posterior nucleus of the thalamus (POm) including the magnocellular part of the medial geniculate body (Mgmc), the ventrobasal complex (VB) and the area of the ventral lateral nucleus (VL) bordering on VB. A second projection originates mainly in the superior vestibular nucleus (S) and in cell group y and terminates mainly in the contralateral nucleus centralis lateralis (CL) and the adjoining nucleus paracentralis (Pc). A third, more modest, pathway originates chiefly in the middle M and D, with a minor contribution from S and cell group y, and terminates in the contralateral ventral nucleus of the lateral geniculate body (GLV). There is some degree of overlap between the origin of these three vestibulothalamic pathways.Abbreviations B.c. brachium conjunctivum - CeM nucleus centralis medialis thalami - CL nucleus centralis lateralis thalami - CM nucleus centrum medianum - D nucleus vestibularis descendons - f cell group f - g cell group g - GLD corpus geniculatum laterale dorsalis - GLV corpus geniculatum laterale ventralis - i.e. nucleus intercalatus - L nucleus vestibularis lateralis - LD nucleus lateralis dorsalis thalami - LIM lamina medullaris interna - Lim nucleus limitans - LP nucleus lateralis posterior thalami - M nucleus vestibularis medialis - MD nucleus medialis dorsalis thalami - MGmc corpus geniculatum mediale, pars magnocellularis - MGp corpus geniculatum mediale, pars principalis - N.cu.e. nucleus cuneatus externus - N.f.c. nucleus fasciculi cuneati - N.mes. V nucleus mesencephalicus nervi trigemini - NR nucleus ruber - N.tr.s. nucleus tractus solitarius - N. VII nervus facialis - N. VIII nervus statoacusticus - PC pedunculus cerebri - Pc nucleus paracentralis thalami - Pf nucleus parafascicularis - p.h. nucleus prepositus hypoglossi - PO posterior thalamic group - PO1 lateral part of PO - POm medial part of PO - Prt nucleus pretectalis - Pul pulvinar - R nucleus reticularis thalami - S nucleus vestibularis superior - Sg nucleus suprageniculatus - SN substantia nigra - Sv nucleus supravestibularis - Tr.s. tractus solitarius - VA nucleus ventralis anterior thalami - VL nucleus ventralis lateralis thalami - VPL nucleus ventralis posterior lateralis - VPL1 lateral part of VPL - VPLm medial part of VPL - VPM nucleus ventralis posterior medialis - x cell group x - y cell group y - z cell group z - V nucleus motorius nerve trigemini - X nucleus dorsalis nerve vagi - XII nucleus nervi hypoglossi     

The origin of the S (slow) potential in the mammalian Lateral Geniculate Nucleus

Summary While recording extracellularly from single neurons in the Lateral Geniculate Nucleus (LGN) of cats and monkeys, one often observes, in addition to action potentials, smaller and slower potentials which have been called S Potentials (Bishop et al. 1962). Injection of the sodium channel blocker tetrodotoxin (TTX) into the eye of the cat causes spontaneous and light evoked S potentials to disappear. However, electrical stimulation of ganglion cells axons at the optic chiasm still elicits S potentials. Previous studies have shown that retinal ganglion cell impulses elicit S potentials. Our results prove that ganglion cell impulses are the ONLY source of these potentials; therefore, one can use them as a measure of ganglion cell input to the LGN.     

Single-cell RT-PCR, in situ hybridization histochemical, and immunohistochemical studies of substance P and enkephalin co-occurrence in striatal projection neurons in rats

Single-cell RT-PCR studies in 3-4-week-old rats have raised the possibility that as many as 20% of striatal projection neurons may be a unique type that contains both substance P (SP) and enkephalin (ENK). We used single-cell RT-PCR, retrograde labeling, in situ hybridization histochemistry, and immunolabeling to characterize the abundance of this cell type, its projection target(s), and any developmental changes in its frequency. We found by RT-PCR that 11% of neurons containing either SP or ENK contained both in 4-week-old rats, while in 4-month-old rats SP/ENK colocalization was only 3%. SP-only neurons tended to co-contain dynorphin and ENK-only neurons neurotensin, while SP/ENK neurons tended to contain dynorphin. Single-cell RT-PCR showed SP/ENK co-occurrence in 4-week-old rats to be no more common among striatal neurons retrogradely labeled from the substantia nigra than among those retrogradely labeled from globus pallidus. Double-label in situ hybridization showed SP/ENK perikarya to be scattered throughout striatum, making up 8% of neurons containing either SP or ENK at 4 weeks, but only 4% at 4 months. Immunolabeling showed that presumptive striatal terminals in globus pallidus externus, globus pallidus internus and substantia nigra pars reticulata that colocalized SP and ENK were scarce. Terminals colocalizing SP and ENK were, however, abundant in the substantia nigra pars compacta. Thus, SP-only and ENK-only neurons make up the vast majority of striatal projection neurons in rats, the frequency of SP/ENK colocalizing striatal neurons is low in adult rats (3-4%), and SP/ENK colocalizing neurons primarily project to SNc but do not appear to be confined to striosomes.     

NeuN is not a reliable marker of dopamine neurons in rat substantia nigra

Quantification of neuronal cell number is a key endpoint in the characterization of neurodegenerative disease models and neuroprotective regimens. Immunohistochemistry for phenotypic markers, followed by unbiased stereology is often used to quantify the relevant neuronal population. To control for loss of phenotypic markers in the absence of cell death, or to determine if other types of neurons are lost, a general neuronal marker is often desired. Vertebrate neuron-specific nuclear protein (NeuN) is reportedly expressed in most mammalian neurons. In Parkinson's disease models, NeuN has been widely used to determine if there is actual nigral dopamine neuron loss or simply loss of tyrosine hydroxylase expression, a prominent phenotypic marker. To date, the qualitative value of NeuN expression as such a marker in the substantia nigra has not been assessed. Midbrain tissue sections from control rats were stained for NeuN and tyrosine hydroxylase and assessed by light or confocal microscopy. Here we report that NeuN expression level in the rat substantia nigra was highly variable, with many faintly stained cells that would not be meet stereological scoring criteria. Additionally, dopamine neurons with little or no NeuN expression were readily identified. Subcellular compartmentalization of NeuN expression was also variable, with many cells dorsal and ventral to the nigra exhibiting expression in both the nucleus and cytoplasm. NeuN expression also appeared to be much higher in non-dopamine neurons within the ventral midbrain. This characterization of nigral NeuN expression suggests that it is not useful as a quantitative general neuronal marker in the substantia nigra.