大鼠内侧视前区支配Barrington核内骶髓投射神经元的光,电镜研究

采用光镜及电镜双标记技术,对大鼠内侧视前区（ＭＰＯ）神经元发出的投射到脑桥Ｂａｒｉｎｇｔｏｎ核的轴突与其内投射到骶髓的神经元的胞体和树突之间的突触关系进行了探讨。将顺行追踪剂结合生物素的葡聚糖胺（ＢＤＡ）注射于ＭＰＯ用来标记它发出的轴突终末;将逆行追踪剂辣根过氧化物酶（ＨＲＰ）注射于脊髓腰骶段,以此标记Ｂａｒｉｎｇｔｏｎ核内投射至腰骶髓的神经元。光镜观察发现Ｂａｒｉｎｇｔｏｎ核内含有大量ＢＤＡ顺行标记的终末及ＨＲＰ逆行标记的树突和胞体,电镜观察确证了ＢＤＡ标记的轴突终末与ＨＲＰ标记的树突和胞体间存在直接的突触联系,且均为对称性突触。此结果提示ＭＰＯ可能通过这一直接的纤维联系调节排尿反射活动。     

大鼠Barrington核内脊髓投射神经元直接接受腰骶髓传入的电镜研究

将结合生物素的葡聚糖胺 (BDA)注射到大鼠腰骶髓后 ,在电镜下观察脑桥Barrington核内腰骶髓投射神经元与来自腰骶髓传入投射纤维间的突触联系。与先前的研究相一致 ,注射BDA到腰 6和骶 1节段后 ,光镜下可见Barrington核内出现大量顺行标记的神经末梢和一定数量的逆行标记细胞。电镜下发现标记的轴突末梢和标记的树突之间存在直接的突触连接。结果表明 ,Barrington核直接接受腰骶髓的传入投射 ,提示大鼠脑桥排尿反射的脊髓内上行投射通路中可能存在一条直接通路。     

大鼠Barrington核内脊髓投射神经元直接接受腰骶髓传入的电镜研究

将结合生物素的葡聚糖胺(BDA)注射到大鼠腰骶髓后,在电镜下观察脑桥Barrington核内腰骶髓投射神经元与来自腰骶髓传入投射纤维间的突触联系.与先前的研究相一致,注射BDA到腰6和骶l节段后,光镜下可见Barrington核内出现大量顺行标记的神经末梢和一定数量的逆行标记细胞.电镜下发现标记的轴突末梢和标记的树突之间存在直接的突触连接.结果表明,Barrington核直接接受腰骶髓的传入投射,提示大鼠脑桥排尿反射的脊髓内上行投射通路中可能存在一条直接通路.     

大鼠中脑导水管周围灰质向孤束核的直接投射

用ＰＨＡ－Ｌ和ＷＧＡ－ＨＲＰ顺行追踪方法,对大鼠中脑导水管周围灰质（ＰＡＧ）向孤束核的投射进行了研究。结果如下：（１）ＰＨＡ－Ｌ和ＷＧＡ－ＨＲＰ顺标纤维和终末在孤束核内的分布状态基本一致,内侧亚核最多,连合亚核、腹外侧亚核和腹侧亚核次之,中间亚核内最少。无论注射区在ＰＡＧ的尾段还是吻段,孤束核的尾中段内的标记纤维和终末均多于吻段。（２）ＰＡＧ尾段向孤束核的投射多于ＰＡＧ吻段。（３）ＰＡＧ腹外侧区向孤束核的投射较多,而背外侧区较少（尾段）或缺如（吻段）。根据作者过去的结果和本实验证据,可见ＰＡＧ向孤束核的投射通路存在定位投射关系。     

大鼠导水管周围灰质注射谷氨酸可使Barrington核神经元表达Fos

形态学研究已发现大鼠内侧视前区（ＭＰＯ）和导水管周围灰质（ＰＡＧ）发出大量轴突,投射至与排尿反射密切相关的Ｂａｒｒｉｎｇｔｏｎ 核。本研究试图通过注射谷氨酸钠到ＭＰＯ或ＰＡＧ后,观察Ｂａｒｒｉｎｇｔｏｎ 核内的Ｆｏｓ表达情况,来了解以上两通路的性质。将谷氨酸钠注射到ＭＰＯ后,只有少量Ｆｏｓ阳性神经元出现在Ｂａｒｒｉｎｇ－ｔｏｎ 核。而将谷氨酸钠注射到ＰＡＧ后,Ｂａｒｒｉｎｇｔｏｎ 核内出现大量的Ｆｏｓ阳性神经元。此结果提示,ＰＡＧ可能对大鼠脑桥排尿反射活动具有兴奋性调节作用。     

多系统变性时脑桥排尿中枢促皮质素释放因子神经元缺失

本研究的目的在于确定位于人类脑桥背侧的脑桥排尿中枢的促皮质素释放因子（corticortophin releasing factor,CRF）神经元,以及在多系统变性（MSA）伴膀胱功能异常的病人中,这些CBF神经元的缺失。 作者以4例临床诊断多系统变性并经神经病理检查证实的尸检脑标本为研究对象,4例其他尸检脑标本为对照。 对脑桥头端进行50微米连续冰冻切片,每隔7片取1片进行免疫组化检查（兔多克隆抗体）。用NADPH-d或同时用NADPH—d和CRF对连续切片染色,以显示脑桥被盖背外侧神经核。蓝斑神经元由其神经黑色素同其他神经元相区别。在脑桥被盖外侧、蓝斑腹侧可见到大量CRF免疫活性神经元。CRF神经元与脑桥被盖背外侧的神经核团中有NADPH-d活性的神经元混杂存在。     

脑桥被盖腔隙梗塞的临床与MRI

报道２０例脑桥被盖腔隙性梗塞患者的临床和ＭＲＩ改变。临床表现为感觉性卒中（ＳＳ）６例、共济失调轻偏瘫（ＡＨ）５例、纳吃－手笨拙综合征（ＤＡ－Ｃｈ）６例和无定位体征的脑桥被盖腔梗１例。ＭＲＩ发现ＳＳ患者的病灶均位于脑桥被盖外侧，ＤＡ－Ｃｈ和ＡＨ患者的病灶则位于脑桥近中线区，ＡＨ的病灶多位于下部脑桥。无定位体征的病灶均见于背内侧区。认为ＭＲＩ是确诊脑桥腔梗病灶的良好手段     

新生期注射谷氨酸单钠对刺激下丘脑弓状核镇痛作用的影响

下丘脑弓状核（ＡＲＣ）是脑内β－内啡肽（β－ＥＮＤ）能神经元胞体集中的一个主要核团。新生期注射谷氨酸单钠（ＭＳＧ）能选择性地损毁ＡＲＣ中的神经元胞体而不累及路过纤维，是研究ＡＲＣ中神经元生理功能的一个良好模型。本实验利用这个实验模型研究刺激ＡＲＣ的镇痛效应。结果发现在这种ＭＳＧ处理的大鼠，刺激ＡＲＣ不再出现明显的镇痛效应（用电刺激鼠尾－嘶叫法测定）。这时脑室内注射β－ＥＮＤ（５μｇ／１０μｌ）能使刺激ＡＲＣ的镇痛效应恢复；若脑室注射多巴胺（ＤＡ，５μｇ／１０μｌ）不仅没有恢复作用，反而能削弱正常大鼠刺激ＡＲＣ的镇痛效应。实验结果提示，经ＭＳＧ处理的大鼠之所以不出现明显的镇痛效应，可能是由于ＡＲＣ中丧失了β－ＥＮＤ能神经元的结果，ＤＡ能神经元在其中不起重要作用。     

大鼠头端延髓腹外侧区神经元对电刺激中脑导水管周围灰质背侧？…

观察了大鼠延髓头端腹外侧区（ｒｏｓｔｒａｌｖｅｎｔｒｏｌａｔｅｒａｌｍｅｄｕｌｌａ，ＲＶＬＭ）神经元电活动对电刺激中脑导水管周围灰质背侧部及腹外侧部（ｄｏｒｓａｌａｎｄｖｅｎｔｒｏｌａｔｅａｌｐｅｒｉａｑｕｅｄｕｃｔａｌｇｒａｙｍａｔｔｅｒ，ｄＰＡＧ和ｖＰＡＧ）的反应，在１３９个神经元中，有９２个被刺激ｄＰＡＧ兴奋。１２５个神经元中，有７２个被刺激ｖＰＡＧ抑制，相当数量的神经元接受ｄＰＡＧ和ｖＰＡ     

颈动脉注射辣椒素激活脑干心血管相关核团的儿茶酚胺神经元

在外周压力感受器去神经支配的大鼠上，用Ｆos蛋白和酪氨酸羟化酶（ＴＨ）的双重免疫组化方法，研究辣椒素的效应是否通过激活脑干核团内儿茶酚胺能神经元而诱发。结果显示，颈动脉注射辣椒素诱发脑干中最后区（ＡＰ）、孤束核（ＮＴＳ）、巨细胞旁外侧核（ＰＧＬ）和蓝斑（ＬＣ）等多个部位出现大量ＦOS样免疫反应（ＦＬＩ）神经元和双标神经元，辣椒素受体阻断剂钌红（ＲＲ）或ＮＭＤＡ受体阻断剂ＭＫ－８０１可明显减弱此效应。以上结果表明，辣椒素的兴奋效应通过激活儿茶酚胺能神经元而诱发，辣椒素受体和／（或）谷氨酸介导这一效应。     

Localization of Barrington's nucleus in the pontine dorsolateral tegmentum of the rabbit.

The localization of Barrington's nucleus in the dorsolateral pons of the rabbit and its projections to the sacral spinal cord were examined by using retrograde and anterograde labeling methods combined with immunohistochemistry. After injection of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) or a fluorescence tracer, tetramethylrhodamine-dextran amine (TMR), into the sacral spinal cord segments, a cluster of neurons labeled with WGA-HRP or TMR were seen in the pontine dorsolateral tegmentum. To identify whether the retrogradely labeled neurons were situated within the locus coeruleus, the sections containing TMR-labeled neurons through the pons were incubated with anti-tyrosine hydroxylase (TH) antibody and observed under epifluorescence microscope. It was shown that the cluster of TMR-labeled neurons in the dorsolateral tegmentum were surrounded by TH-positive neurons, but they were negatively immunostained with TH-like immunoreactivity. In anterograde experiment, injection of WGA-HRP into the dorsolateral tegmentum resulted in many anterogradely labeled nerve fibers and terminals in the sacral spinal cord, including the sacral parasympathetic nucleus. The present results suggest that the cluster of neurons in the dorsolateral tegmentum of the rabbit may correspond to Barrington's nucleus revealed in the rat and cat, and thus may be involved in micturtion reflex of the rabbit.     

Corticotropin-releasing factor (CRF) immunoreactivity in the dorsolateral pontine tegmentum: further studies on the micturition reflex system

A cluster of neurons in the pontine tegmentum thought to correspond with the micturition reflex center was retrogradely labeled following the injection of the fluorescent tracer True Blue into the sacral spinal cord. Simultaneous immunofluorescence staining indicated that these neurons display corticotropin-releasing factor (CRF)-like immunoreactivity. Also, CRF-positive varicose fibers were detected in the intermediolateral column of the sacral cord. The results indicate the presence of CRF or a CRF-like peptide in a descending projection to the spinal cord that may be involved in regulating the micrutition reflex.     

Spinal projections from the lower brain stem in the cat as demonstrated by the horseradish peroxidase technique. II. projections from the dorsolateral pontine tegmentum and raphe nuclei

The descending projections to the spinal cord arising from the dorsolateral pontine tegmentum and brain stem raphe nuclei have been investigated by means of the horseradish peroxidase (HRP) technique. Particular attention was taken to clarify the cells of origin and the funicular trajectory of these spinal projections.After injections of HRP into the spinal cord, a significant number of HRP labeled neurons were observed in the following dorsolateral pontine tegmental structures: (1) an area ventral to the nucleous cuneiformis; (2) principal locus coeruleus; (3) locus coeruleus α; (4) locus subcoeruleus; (5) Kölliker-Fuse nucleus; and (6) nucleus parabrachialis lateralis. As a rule, the projections are ipsilateral and the descending fibers course in the ventral part of the lateral funiculus.As concerns the raphe-spinal projections, we have demonstrated that the nucleus raphe dorsalis also sends axons to the cervical segment of the spinal cord. Furthermore, in accord with previous reports, HRP labeled cells were also identified in the nucleus raphe magnus, pallidus and obscurus, but not in the nucleus raphe centralis superior and pontis.On the whole the present study further clarified the organization of spinal projections from the dorsolateral pons and raphe nuclei and provided some additional anatomical data for the physiology of the tegmentospinal and raphe-spinal projections.     

Spinal projections from the nucleus locus coeruleus and nucleus subcoeruleus in the cat and monkey as demonstrated by the retrograde transport of horseradish peroxidase

The rostral pons of the cat and rhesus monkey were examined for the presence of labeled cells following injections of horseradish peroxidase (HRP) into the lumbar spinal cord. Labeled cells were found in the ipsilateral dorsolateral pontine tegmentum and in the contralateral ventrolateral pontine reticular formation. In both the cat and monkey, labeled cells were located in the nucleus locus coeruleus, nucleus subcoeruleus, in or near the Kölliker-Fuse nucleus, and in the ventral part of the lateral parabrachial nucleus. There is a striking similarity between the distribution of HRP-labeled cells in the dorsolateral pontine tegmentum of the cat and monkey and that of catecholamine-containing cells observed in this area in previous studies.     

Barrington's nucleus in the guinea pig (Cavia porcellus): location in relation to noradrenergic cell groups and connections to the lumbosacral spinal cord

Micturition is largely controlled by Barrington's nucleus in the dorsolateral tegmentum of the pons. This nucleus coordinates simultaneous bladder contraction and external urethral sphincter relaxation, by means of a specific pattern of projections to the lumbosacral spinal cord. The most widely used small animal model in neurourological research is the rat. However, urodynamic studies suggest that, in sharp comparison to rat, guinea pig micturition is very similar to human micturition. Therefore, the present study, using retrograde and anterograde tracing and double immunofluorescence, was designed to investigate the location of Barrington's nucleus in the guinea pig, to identify Barrington's nucleus projections to the spinal cord and to clarify the relationship of Barrington's nucleus to pontine noradrenergic cell groups. Results show that Barrington's nucleus is located in the dorsolateral pons, projects to the intermediolateral and intermediomedial cell groups of the lumbosacral spinal cord and is clearly distinct from the pontine noradrenergic cell groups. These results show that the neuroanatomical circuitry in the spinal cord and brainstem that controls micturition in the guinea pig is similar to that in rat. This means that the differences between rat and guinea pig micturition on a behavioral level are not the result of different neuroanatomical connections in these parts of the central nervous system. These results provide a neuroanatomical basis for further neurourological studies in guinea pig.     

Afferent projections to the pontine micturition center in the cat

The pontine micturition center (PMC) or Barrington's nucleus controls micturition by way of its descending projections to the sacral spinal cord. However, little is known about the afferents to the PMC that control its function and may be responsible for dysfunction in patients with urge-incontinence and overactive bladder. In five female cats, wheatgerm agglutinin-conjugated horseradish peroxidase (WGA-HRP) injections were made in the PMC and adjoining dorsolateral pontine tegmentum. Retrogradely labeled neurons were found in a large area, including the medullary and pontine medial and lateral tegmental field; dorsomedial, lateral, and ventrolateral periaqueductal gray matter (PAG); posterior hypothalamus; medial preoptic area (MPO); bed nucleus of the stria terminalis; central nucleus of the amygdala; and infralimbic, prelimbic, and insular cortices. To verify whether these areas indeed project specifically to the PMC or perhaps only to adjacent structures in the pontine tegmentum, in 67 cats (3)H-leucine or WGA-HRP injections were made in each of these regions. Five cell groups appeared to have direct connections to the PMC, the ventromedial pontomedullary tegmental field, the ventrolateral and dorsomedial PAG, the MPO, and the posterior hypothalamus. The possible functions of these projections are discussed. These results indicate that all other parts of the brain that influence micturition have no direct connection with the PMC.     

Direct projections from the dorsolateral pontine tegmentum to pudendal motoneurons innervating the external urethral sphincter muscle in the rat

Direct projections from the dorsolateral pontine tegmentum to pudendal motoneurons innervating the external urethral sphincter and the external anal sphincter muscles were examined in the rat by the tract-tracing methods utilizing retrograde transport of cholera toxin B subunit and anterograde transport of biotinylated dextran amine. The dorsolateral pontine tegmental region, corresponding to the micturition reflex center of Barrington, was confirmed to send bilaterally, with an ipsilateral dominance, projection fibers to the spinal parasympathetic nucleus (inferior intermediolateral nucleus). The micturition reflex center of Barrington, however, did not seem to send many projection fibers to the ventral horn of the lumbosacral cord segments, whereas the region immediately ventral to the micturition reflex center of Barrington was found to send bilaterally, with a contralateral dominance, projection fibers to the dorsolateral group of pudendal motoneurons in both the male and female rats. In the female rat, the dorsolateral group of pudendal motoneurons are comprised primarily of motoneurons that innervate the external urethral sphincter muscle. The dorsomedial group of pudendal motoneurons, which contain motoneurons that innervate the external anal sphincter and the bulbocavernosus muscles, did not seem to receive major projections from the dorsolateral pontine tegmental regions. It was also observed that the locus coeruleus sent some projection fibers bilaterally to the spinal parasympathetic nucleus but only a few to the ventral horn of the lumbosacral cord segments. Thus, the present results indicate that the dorsolateral group of pudendal motoneurons containing those innervating the external urethral sphincter muscle receive pontospinal projection fibers mainly from the dorsolateral pontine tegmental region immediately ventral to the micturition reflex center of Barrington. © 1995 Wiley-Liss, Inc.     

Bladder contractility-related neurons in Barrington's nucleus: axonal projections to the spinal cord in the cat

Barrington's nucleus projects directly to the sacral parasympathetic nucleus. The purpose of this study was to clarify whether neurons in Barrington's nucleus that increase their firing during bladder contractions project to the spinal cord and, if so, to which level(s) the axon reaches. Single units were recorded in Barrington's nucleus of cat with glass microelectrodes, and the termination level of descending axons was determined by antidromic stimulation of the spinal cord. Thirty-nine neurons projecting to the spinal cord were located in rostral parts of the dorsolateral pontine tegmentum, medial and ventral to the mesencephalic trigeminal tract. This finding is consistent with previous neuronal tracing studies. All neurons increased their firing rates during contraction associated with micturition. In 19 examined neurons, the most caudal level of the descending axon distributed between the L7 and the S3 level. Stimulation of the axon at this most caudal level resulted in antidromic spike latencies ranging between 19.5 msec and 45.0 msec. These antidromic latencies were much smaller than previously reported orthodromic conduction times between neurons in Barrington's nucleus and sacral preganglionic neurons innervating the bladder. The mean conduction velocity of the descending axon from the cell body to the border between Th13 and the L1 ranged between 7.2 m/sec and 27.7 m/sec. The decrease of the mean conduction velocity was observed at the lumbar as well as at the sacral segments, suggesting that axons issue collaterals to the lumbar level as well as to the sacral level.     

Anatomical and physiological observations on supraspinal control of bladder and urethral sphincter muscles in the cat

In 15 cats injections of 3H-leucine were made in the pontine tegmentum. Injections in the medial part of the dorsolateral pontine tegmentum (M-region) resulted in specific projections to the sacral intermediomedial and intermediolateral cell groups. The intermediolateral cell group contains preganglionic parasympathetic neurons that form the motor supply of the detrusor muscle of the bladder. Injections in the lateral part of the pontine tegmental field (L-region) produced labeled fibers in the nucleus of Onuf, which contains motoneurons innervating the pelvic floor including the anal and urethral sphincters. L-region projections to the sacral preganglionic parasympathetic neurons and M-region projections to the nucleus of Onuf were very limited or absent. In 12 cats physiological experiments were performed. Electrical stimulation in the L-region elicited a prompt increase in the pelvic floor EMG and urethral pressure but had little influence on the intravesical pressure. Stimulation in the M-region elicited a prompt decrease in the pelvic floor EMG and urethral pressure followed, after a delay of 2 seconds, by an increase in the intravesical pressure, so simulating normal micturition.     

Amygdaloid and pontine projections to the ventromedial nucleus of the hypothalamus

Amygdaloid and pontine projections to the feline ventromedial nucleus of the hypothalamus (HVM) were studied with retrograde transport of horseradish peroxidase (HRP) and anterograde transport of tritiated amino acids. Following injections of HRP into HVM, amygdaloid neurons were labeled in the ipsilateral cortical and medial nuclei and the ventral portion of the parvocellular part of the basal nucleus. In experiments in which HRP was injected into the tuberal hypothalamus following stria terminalis lesions, it was determined that amygdaloid neurons projecting to HVM by way of the stria terminalis were located in the cortical and medial nuclei while those projecting through another route, presumably the ventral amygdalofugal pathway, were found in the rostral part of the medial nucleus and the parvocellular basal nucleus. Following HRP injection into lateral hypothalamus at the level of HVM, labeled neurons were seen in the magnocellular basal nucleus. After preoptic injections, neurons containing the HRP reaction product were in cortical and medial nuclei and magnocellular and parvocellular parts of the basal nucleus. In addition to cells in the amygdala, rostral pontine neurons were labeled after HRP injections into HVM. The cells were located ipsilateral to the injection, mostly in the dorsal nucleus of the lateral lemniscus, lateral and dorsolateral to the brachium conjunctivum. The pontine cells labeled following HVM injections of HRP were different from those labeled following lateral hypothalamic and preoptic region injections. The pontine projection to HVM was confirmed using axoplasmic transport autoradiography. A mixture of tritiated leucine and tritiated proline was injected into the lateral pontine region labeled after HRP injections into HVM. Labeled axons ascending in the medial forebrain bundle terminated throughout the rostro-caudal extent of HVM.