三叉神经初级传入纤维的中枢投射——HRP跨节追踪研究

分别向猫眶上神经、眶下神经和下牙槽神经的神经干内注射20％HRP(Toyobo,RZ 3.3)溶液,跨节追踪了三叉神经初级传入纤维在中枢内的分布。 1.三叉神经的初级传入纤维在中枢内都与三叉神经感觉核簇发生全面的联系。其中,眶上神经向三叉神经脊束核的尾侧亚核第Ⅰ～Ⅴ层都有大量的投射,而向吻侧,则标记终末只位于各亚核腹侧的极小范围内。眶下神经在三叉神经感觉核簇中的标记终末分布范围较大,以尾侧亚核的中央部和感觉主核腹侧2/3部的标记终末最为密集。下牙槽神经在尾侧亚核和吻侧亚核的标记终末数量和分布范围最大。 2.含有大量来自额部皮肤和上颌胡须的触觉传入纤维的眶上、眶下神经除向感觉主核投射外,也向其它各亚核特别是尾侧亚核有大量的投射。含有较大量痛觉传入纤维的下牙槽神经不仅向脊束核投射,在感觉主核的投射也是明显的。因而,确证了感觉主核接受触觉,脊束核接受痛温觉传入投射的传统看法是不符合实际的。 3.上述三神经都向尾侧亚核内侧相当于脊髄后角第Ⅴ层的区域有明显的投射。结合文献,本文作者支持此第Ⅴ层应归属于尾侧亚核的看法,并推论此区可能有三叉神经传入纤维和其它脑结构来源的纤维的汇聚。     

大白鼠三叉神经核至小脑核的纤维投射

本实验用微电泳方法将HRP分别导入20只大白鼠的小脑核,研究三叉神经各核至小脑核的纤维投射。结果表明,三叉神经各核均向小脑核发出纤维投射。其中以三叉神经脊束核极间亚核和吻侧亚核最多,三叉神经脊束核尾侧亚核和三叉神经感觉主核次之,三叉神经中脑核和三叉神经运动核最少。此外,在三叉神经运动核的腹外侧和三叉神经根内也有向小脑核投射的起源细胞。来自中脑核的纤维多终于顶核和间位核前部,来自脊束核和感觉主核的纤维较多地终止于间位核后部和齿状核。运动核的纤维终止于顶核、间位核前部和齿状核。起源于三叉神经运动核腹外侧,三叉神经根内细胞群的纤维,在小脑核中有和三叉神经感觉核簇相似的终止。三叉—小脑核的纤维投射是双侧性的,但以同侧为主。     

猫红核向三叉神经脊束核尾侧亚核的投射——HRP法研究

向猫三叉神经脊束核尾侧亚核注入30％HRP溶液,在对侧红核吻侧2/3段的背外侧角部出现集中的标记细胞群。此部主要由多种形态的中、小型神经元组成,由红核中段开始出现,向吻侧逐渐向背外方突出。通过与向延髓下部网状结构和脊髓C_(2～3)节注入HRP的对照例以及关于红核—脊髓投射的文献对比,证明了此部是红核向对侧尾侧亚核发送纤维的特定区域。经过全面分析还发现,红核向下位结构的投射显示着吻侧2/3段向脊髓颈上段以上结构、尾侧2/3段向颈下段(颈膨)以下结构投射的体部定位关系。     

一氧化氮合酶阳性结构在大鼠三叉神经感觉核簇内的分布及其与面部伤害性刺激诱发的FOS蛋白表达的关系

用还原型尼克酰胺腺嘌呤二核苷酸脱氢酶组织化学技术与ＦＯＳ免疫组化（ＡＢＣ法）相结合的方法，观察了大鼠三叉神经感觉核簇内一氧化氮合酶阳性神经元和纤维的分布及其与面部伤害性刺激诱发的ｃ－ｆｏｓ原癌基因蛋白表达的关系．证明，浓密的一氧化氮合酶阳性纤维和终末分布于三叉神经脊束核尾侧亚核的Ⅰ和Ⅱ层，阳性成分呈蓝黑色的带状分布，而在三叉神经感觉核簇的其余核区内很稀疏．一氧化氮合酶阳性神经元胞体与面部伤害性刺激诱发的ｃ－ｆｏｓ原癌基因蛋白表达的阳性神经元在此核簇内的分布节段非常相似，都主要存在于与伤害性传入传递和调控有关的三叉神经脊束核尾侧亚核，并且二者都主要分布于与痛觉调控有关的浅层．约有１０～１５％的一氧化氮合酶阳性神经元同时呈ｃ－ｆｏｓ原癌基因蛋白表达．在三叉脊束核尾侧亚核的Ⅲ～Ⅴ层仅出现散在的阳性细胞，除在吻侧亚核的背内缘与孤束核交界处有少量一氧化氮合酶同性神经元外，在三叉神经感觉核簇的其余核区两者均几无表达．本文及文献结果提示，一氧化氮可能对面部伤害性信息的传递和调控起重要作用．     

GABA样神经元和GABA能三叉一丘脑投射神经元在三叉神经感觉核簇的分布及形态学特征

用直接抗GABA免疫组化方法和与HRP逆行追踪相结合的双标记法在光镜下观察了GABA样神经元和GABA能丘脑投射神经元在大鼠三又神经惑觉核簇的分布和形态特征。结果显示:GABA样神经元广泛存在于三叉神经感觉核簇的各亚核中,但在每一亚核和尾侧亚核的各层,其分布状况和细胞形态特征各异。在尾侧亚孩,GABA样神经元的分布密度为Ⅰ、Ⅱ层>Ⅳ、Ⅴ层>Ⅲ层;在极间亚核,GABA样细胞分为背、腹二群,以腹侧群为主;在吻侧亚核,分为背内侧群、内侧带群和腹外侧群三群;在感觉主核分为背内侧群和腹外侧群;在三叉上核分为吻内侧群和尾外侧群。同样,本文首次发现,GABA能丘脑投射神经元也广泛存在于三叉神经感觉核簇各核中,而且在各亚核及各层中其分布密度及细胞形态也不相同。在尾侧亚核,双标细胞占38.6%,主要分布在Ⅰ、Ⅱ层,具有较长附突;在极间亚核,双标细胞占40%,主要分布在腹侧群;在吻侧亚核中仅在腹侧群有少量小的双标细胞;在感觉主核,双标细胞占20-30%,主要集中在背内侧群,腹外侧群仅有少量;在三叉上核,双标细胞仅出现在尾外侧群。结果提示:GABA对三叉神经感觉核簇中的各种深浅感觉功能的传导和整合可产生广泛的抑制影响,但其影响形式、程度和机制可能各不相同。     

大鼠三叉神经脊束核尾侧亚核向三叉神经感觉核簇其它核团的投 …

将逆行追踪剂荧光金分别注射到三叉神经感觉主核,三叉神经脊束核吻侧亚核和极间亚核,观察到尾侧亚核Ⅰ－Ⅴ层的神经元均向同侧上述核团发现上行投射。值得注意的是尾侧亚核Ⅱ层也有神经元向上述各核团投射。     

舌咽、迷走神经初级传入与三叉神经初级传入在三叉神经脊束间质核的汇聚

三叉神经脊束间质核是位于三叉神经脊束内的一些灰质团块，三叉神经的一些分支和舌咽、迷走神经均有初级传入纤维投射于此核．为了更确切地认识这些传入投射在此核内的分布范围及其相互关系，本文在光学显微镜下详细观察了Nissl引染色和未染色的透明大鼠脑切片，利用计算机图像分析技术首先重塑此核的立体构形，继之又重塑了经HRP跨节追踪方法显示的三叉神经分支的舌神经、眼下神经以及舌咽、速走神经初级传入终末向此核内投射的立体分布状况．结果显示三叉神经脊束间质核在吻尾方向上整体呈连续且中间膨大的桂形佳状结构；投射于此核的各神经的终末量多少、分布区域虽然都不尽相同，但三叉神经躯体初级传入和Ⅸ、X脑神经内脏初级传人终末在此梭形结构中段膨大部呈明显的重叠分布。本文结果为内脏传入和面目部躯体使人信息在三叉神经脊柬问质核神经元的汇聚提供了形态学根据．     

家兔躯体(坐骨神经)和内脏(膀胱)初级传入神经元向骶髓后连合核区的投射—HRP跨越神经节追踪观察

本文作者研究了膀胱(内脏)及坐骨神经(躯体)初级传入纤维向脊髓的投射。发现内脏传入纤维和躯体本体觉粗纤维都向S_2—S_4节段后连合核区投射,两者的投射区有重叠。推测内脏传入和躯体本体觉传入的纤维在后连合核可能有汇聚。另外,根据躯体本体党纤维在髓内跨节段分布的范围和位置以及盆腔脏器初级传入的投射位置,结合文献分析和讨论了脊髓后连合核的位置和形态。提出在脊髓内存在着一个和脑部的孤束核在形态及功能上酷似的脊髓后连合核的见解。它在吻侧以对称的狭细细胞带起于胸髓下段,向尾侧逐渐扩大位于Ⅵ层内侧部,到骶髓成为位于中央管背外方的核团,S_3以下两侧者合并形成位于中央管背侧后连合区的较大核团,一直可追踪到尾髓。     

猫三叉神经脊束核尾侧亚核第V层中红核下行纤维终末的超微结构特征——溃变及HRP电镜法

本文报道用电解法或注入海人酸毁损红核吻侧2/3部,另外,再将WGA-HRP溶液注入该部,在电镜下观察投射到对侧三叉神经脊束核尾侧亚核第Ⅴ层中的溃变终末和HRP标记终末的形态特征。发现溃变和HRP标记终末多含圆形或混合型小泡,大多数终末与中、小型树突形成对称型突触,从而推测红核下行纤维可能对第Ⅴ层神经元起抑制性调节作用,可影响面、口部躯体感觉的传入。本文提示红核不仅参与躯体不随意运动的调控,可能对面、口部感觉传递也起整合作用。另外,本文对溃变电镜和HRP(TMB反应)标记电镜的技术方法进行了讨论。     

三叉神经初级传入纤维与孤束核的联系——HRP跨越神经节追踪研究

本文用HRP跨节追踪技术在光镜下观察了猫的眶上神经、眶下神经、耳颞神经、颊神经、舌神经和下牙槽神经的初级传入纤维向孤束核的投射状况。另外,向舌咽、迷走和鼓索神经也注入HRP进行了观察和对比。结果表明,上述三叉神经各分支中只有舌神经和下牙槽神经向孤束核投射。舌神经的标记出现于孤束核的闩以上部分,以三叉神经吻侧亚核尾段水平的部位最为浓密,标记终末多分布于腹外侧亚核、中间亚核和内侧亚核。下牙槽神经只有少量标记终末呈斑块状局限分布于闩附近的孤束核间质亚核区,小部分投射于连合核。舌咽神经投射至孤束核全长,以内侧亚核区为最多。迷走神经的大量纤维主要投射于极间亚核平面的孤束核。鼓索神经大部投射至孤束核吻极段。本文对比分析了三叉神经初级传入与Ⅶ、Ⅸ、Ⅹ神经内脏传入在孤束核分布的相互关系,结合文献讨论了投射到孤束核的三叉初级传入神经的性质。     

Ascending and descending internuclear connections of the trigeminal sensory nuclei in the cat. A study with the retrograde and anterograde horseradish peroxidase technique

The distribution of cells of origin of ascending and descending internuclear connections in the trigeminal sensory nuclei was studied by the retrograde horseradish peroxidase technique in the cat. The termination of collaterals of these ascending axons was also studied by the anterograde transport of horseradish peroxidase. Following injections of horseradish peroxidase into the ventral part of the principal sensory nucleus and the adjacent reticular formation many small neurons were labeled ipsilaterally in the whole area of the caudal portion of the nucleus interpolaris and in laminae III and IV of the nucleus caudalis. Labeled neurons were also found in laminae I and V. Injections limited to either nucleus oralis, the ventral part of the principal sensory nucleus and the medial parabrachial nucleus labeled similar types of neurons in the above regions with a topographic relationship; neurons in the dorsal part of the nuclei caudalis and interpolaris project, dorsally, to rostral portions of the trigeminal sensory nuclei while those in the ventral part of the nuclei caudalis and interpolaris project ventrally. Anterograde labeling of axons arising from the nucleus caudalis demonstrates that the axons ascend in the intranuclear bundles and the adjacent reticular formation, and give off collaterals to the nuclei interpolaris and oralis, and the ventral part of the principal sensory nucleus. Injections limited to the nucleus caudalis labeled small neurons in the rostral portion of the nucleus oralis and the caudal portion of the nucleus interpolaris. The present study suggests that these ascending and descending internuclear connections of the trigeminal sensory nuclei may modulate transmission of afferent inputs to various projection sites, such as thalamus, superior colliculus, cerebellum and spinal cord.     

5-HT-immunoreactive fibers in the trigeminal nuclear complex of the rat

Summary The distribution of serotonin immunoreactive (5-HT-IR) fibers in the trigeminal nuclear complex of the rat was mapped. In the sensory nuclei, innervation appeared to be dense in areas primarily related to nociceptive afferent activity, and sparse in areas primarily related to nonnociceptive afferent activity. Specifically, the marginal and gelatinosa layers of the spinal subnucleus caudalis contained many 5-HT-IR fibers while few labeled fibers were seen in the magnocellular portion of subnucleus caudalis or in the principal sensory nucleus. The spinal subnuclei oralis and interpolaris were sparsely innervated except for a few areas which contained more 5-HT-IR fibers. The motor nucleus contained as many immunoreactive fibers as the subnucleus caudalis, although fibers in the motor nucleus were thicker and varicosities more irregularly spaced than in caudalis.This research was supported by grant BNS-79-06474 from the National Science Foundation awarded to Efrain Azmitia     

The efferent connections of the nuclei of the descending trigeminal tract in the mallard (Anas platyrhynchos L.)

The efferent and intranuclear connections of the nuclei of the descending trigeminal tract of the mallard have been studied with lesion methods, and by axonal transport techniques following injections of tritiated leucine, and of horseradish peroxidase.The large subnucleus oralis neurons, including those belonging to the nucleus of the ascending glossopharyngeal tract, have proven to be the sole origin of trigeminocerebellar connections. The cerebellar afferents are of the mossy fiber type, and terminate predominantly in lobules V, VI and VII, and possibly, lobule IV. Trigeminocerebellar projections are ipsilateral except for the vermal area.Subnucleus interpolaris is the main source of intratrigeminal fibers that terminate in subnucleus oralis and the ventral part of the main sensory nucleus. These intranuclear connections are bilateral, but the medium-celled caudal part of subnucleus interpolaris in particular contains the majority of bi- and/or contralaterally projecting neurons. Additionally, the small cells in the rostral part of subnucleus interpolaris project ipsilaterally upon the parabrachial region, and upon the lateral reticular formation.Projections upon the parabrachial region furthermore emanate bilaterally from layer I of the rostral subnucleus caudalis. A minor part of layer I neurons sends its axons contralaterally along with those of the dorsal column nuclei toward the thalamic nucleus dorsolateralis posterior. Associated with the medial lemniscus, contralateral termination is also present in the lateral part of the ventral lamella of oliva caudalis, in the marginal zone of nucleus mesencephalicus lateralis, pars dorsalis and immediately surrounding intercollicular grey and, finally, in the nucleus intercalatus thalami. Furthermore, a bilaterally descending projection from subnucleus caudalis upon layers I and II of the rostral cervical cord was observed. Close to their origin subnucleus caudalis neurons project upon the adjoining caudal part of the lateral reticular formation.     

The cells of origin of the trigeminothalamic,trigeminospinal and trigeminocerebellar projections in the cat

Using the retrograde horseradish peroxidase technique, we have examined the distribution of labeled thalamic-, spinal- and cerebellar-projecting neurons in the trigeminal sensory nuclei of the cat.Injections into the nucleus ventralis posterior of the thalamus resulted in labeling of neurons in lamina I (subnucleus zonalis), the deeper part of lamina IV (the subhucleus magnocellularis) of the nucleus caudalis and in lamina V (the lateral extension of the nucleus medullae oblongatae centralis) on the contralateral side. A very large number of labeled small neurons were observed mainly in the caudal part of the nucleus interpolaris and in the ventral division of the principal sensory nucleus on the contralateral side and in the dorsal division of the principal sensory nucleus on the ipsilateral side.Injections into the known projection areas of the cerebellar cortex labeled mainly ipsilaterally the trigeminocerebellar neurons in a restricted ventrolateral area of lamina IV of the nucleus caudalis at its rostral level and in lamina V. Many labeled neurons were also observed in the nucleus interpolaris. Although the distribution overlapped with that of the trigeminothalamic neurons, the greatest majority were concentrated in its rostral part where the trigeminothalamic neurons were very small in number. In addition, labeled neurons were observed in the rostral part of the nucleus oralis and the ventralmost part of the ventral division of the principal sensory nucleus. No labeled neurons were observed in the dorsal division of the principal sensory nucleus and the mesencephalic nucleus.The trigeminospinal neurons were labeled mainly ipsilaterally following injections into the upper cervical cord. They were located in laminae I and III, the deeper part of lamina IV of the nucleus caudalis and in lamina V. Only scattered labeled neurons were found in the nucleus interpolaris. The number of labeled neurons increased in the nucleus oralis at the level of the superior olive. They tended to be distributed around or dorsal to the groups of the trigeminothalamic neurons at the caudal part of the principal sensory nucleus. No neurons of the principal sensory nucleus appeared to project to the spinal cord. Based on the large size and location, the trigeminospinal neurons could be differentiated from the other projection neurons in the nucleus oralis.The present study demonstrates that the trigeminal sensory nuclei are composed of groups of neurons with different projections, since the main aggregations are localized at different levels. However, it should be examined whether the neuronal groups, which are labeled from the different structures in similar locations, are composed of individual neurons projecting to more than one of these structures.     

猫冠状回向三叉脊束核的定位投射

本实验用WGA—HRP法研究了猫冠状回向三叉脊束核的投射。结果是:(1)冠状回前部投至两侧三叉脊束核的背内侧部,对侧稍多于本侧。向尾侧亚核的投射,由吻侧向尾侧逐渐减少,在延髓下部平面只有对侧投射。(2)冠状回中、后部基本上投至对侧三叉脊束核。在尾侧亚核,中部主要投至吻侧半,向尾侧逐渐减少,于延髓下部平面消失;后部来的投射山吻侧向尾侧逐渐增多,核心部位移至尾侧半并延伸到最尾端。在极间亚核和吻侧亚核,其投射区随注射部位从前向后移而由内向外移。(3)于尾侧亚核,投射区主要为Ⅲ,Ⅳ层,但Ⅰ、Ⅱ层内也有少量标记终末支。     

Substance P-like immunoreactive fibers in the trigeminal sensory nuclei of the pit viper, Trimeresurus flavoviridis

Substance P-like immunoreactive nerve fibres were located in the trigeminal sensory system of the infrared-sensitive snake, Trimeresurus flavoviridis, using the immunohistochemical method. There are two trigeminal sensory systems in the medulla of this animal: the descending nucleus and the lateral descending nucleus. The descending nucleus is equivalent to the trigeminal spinal nucleus in other vertebrates, and the lateral descending nucleus is a special trigeminal sensory nucleus belonging to the infrared sensory system. In the present study we determined that the lateral descending nucleus is completely ensheathed by large numbers of substance P-like immunoreactive fibers. The distribution of these fibers seems to be similar to that of the thin vagal unmyelinated fibers, rather than to that of the thick trigeminal myelinated fibers. More substance P-like immunoreactive nerve fibers were observed in the lateral descending tract than in the descending tract. Almost no dense substance P-like immunoreactive fibers were found in these tracts rostral to the lateral descending nucleus or rostral to the subnucleus caudalis of the descending nucleus. The substance P-like immunoreactive fibers in the lateral descending tract extended to those of Lissauer's tract of the spinal cord, and the substance P-like immunoreactive fibers surrounding the Lissauer's tract were similar in appearance to those of the lateral descending nucleus. This nucleus seems to have developed from the elements existing in Lissauer's tract, and also to have a similar modulating function. The primary nucleus of the infrared sensory system is the most substance P-like immunoreactive nucleus in the trigeminal sensory system of this animal. Even in the trigeminal sensory system, substance P-like immunoreactive fibers seem not to be related solely to the nociceptive sensation.     

Jaw-muscle spindle afferent feedback to the cervical spinal cord in the rat

Putative synaptic contacts between masticatory-muscle spindle afferents and brainstem neurons which project to the cervical spinal cord were studied in rats by combining retrograde and intracellular neuronal labeling. Spinal cord projecting neurons were retrogradely labeled via injection of horseradish peroxidase unilaterally or bilaterally into cervical spinal cord segments C2 through C5. Twenty-four hours after the injection of horseradish peroxidase, one to five jaw-muscle spindle afferent axons were physiologically identified and intracellularly stained with biotinamide on each side of the brainstem. Horseradish-peroxidase-labeled neurons were found bilaterally in the supratrigeminal region, trigeminal principal sensory nucleus, parvicellular reticular nucleus including its alpha division, spinal trigeminal subnuclei oralis and interpolaris and the medullary reticular formation. Retrogradely labeled neurons were most numerous in the spinal trigeminal subnucleus oralis, parvicellular reticular formation and the ventral part of the spinal trigeminal subnucleus interpolaris. A small number of horseradish-peroxidase-labeled neurons were also present in the trigeminal mesencephalic nucleus and spinal trigeminal subnucleus caudalis. Appositions between jaw-muscle spindle afferent boutons and spinal projecting neurons were found in the supratrigeminal region, dorsomedial portions of the trigeminal principal sensory nucleus and spinal trigeminal subnuclei oralis and interpolaris, and the parvicellular reticular formation including its alpha division. Putative synaptic contacts were most frequent in the parvicellular reticular formation and the dorsomedial portion of the trigeminal subnucleus oralis. These results indicate that some orofacial proprioceptive feedback transmitted via the mesencephalic trigeminal nucleus reaches the cervical spinal cord directly and suggests that jaw-muscle spindle afferent feedback reaches the cervical spinal cord predominately via relays in the dorsomedial part of the spinal trigeminal subnucleus oralis and the parvicellular reticular formation. It is hypothesized that these pathways are primarily involved in the coordination of jaw and neck movement during mastication and biting. Materials and methods 27 January 1999 / Accepted: 9 May 1999     

Projections of the ascending somesthetic pathways to the cat superior colliculus visualized by the horseradish peroxidase technique

Summary Projections of the somesthetic ascending pathways to the superior colliculus (SC) of the cat have been demonstrated by means of the horseradish peroxidase (HRP) tracing technique. Following HRP injection in one SC, marked neurons were found in the contralateral dorsal horn and in the contralateral dorsal column nuclei, mainly the cuneate nucleus. Moreover, in the contralateral trigeminal complex, the sub-nucleus caudalis of the spinal nucleus of the Vth nerve, and the subnucleus oralis plus the main sensory trigeminal nucleus were labeled. Thus, the anterolateral system and the lemniscal system subserving face and forelimb sensation send afferent fibers to the contralateral SC.