Neuronal cell types in the anterior ventral thalamic nucleus of the camel

The anterior ventral nucleus neurons in of the camel brain were morphologically studied by Golgi impregnation method. Two neuronal types of were found in the camel anterior ventral thalamic nucleus, namely, Golgi-type I neurons and Golgi-type II neurons. Those neurons were generally similar to their counterparts in the human thalamus. The Golgi-type I neurons exhibited medium to large cell body (mean diameter = 25 μm) which was either multipolar or triangular in shape. They had from 3 to 10 primary dendrites with many branches but with no spines or appendages. The Golgi-type II neurons had small to medium size (somatic mean diameter = 17.5 μm), their cell bodies were variable in shape, some were round, and others were multipolar or fusiform. These cells bodies had two to six primary dendrites with few branches that may have spines and/or grape-like appendages. Our findings shed some light on the anterior ventral thalamic nucleus structure of the camel as one of the strongest adaptive mammals to the hard climatic conditions.     

Efferent projections of nucleus locus coeruleus: topographic organization of cells of origin demonstrated by three-dimensional reconstruction

The present study examines the spatial distribution within rat locus coeruleus of neurons projecting to particular brain regions. In order to accurately recreate, in digital and pictorial formats, the spatial distribution of neurons for the entire nucleus locus coeruleus, three-dimensional reconstructions were created which specified the location of each individual Nissl-stained locus coeruleus cell in each of five nuclei. Dynamic computerized displays were visually analyzed and statistically compared. The nuclei from different brains were found to be strikingly similar in density and distribution of cells. In order to determine whether the cells of origin for particular locus coeruleus projections were clustered within the nucleus, reconstructions were created of the distributions of cells labeled by injections of a retrograde tracer, horseradish peroxidase, into particular terminal regions. Groups consisting of animals with injections into the same target areas were visually and statistically compared. The cells of origin of most efferent projections were found to be spatially organized within locus coeruleus. Specifically, projections to both the dorsal and ventral hippocampus originated solely from the dorsal segment of the nucleus, while spinal cord projections originated from ventral-posterior locus coeruleus. Cells of origin of cerebral and cerebellar cortical efferents, as well as hypothalamic efferents, exhibited less clustering, although reliable differences in distribution were observed. The most striking example of clustered cells of origin was exhibited by the large norepinephrine-containing cells constituting the anterior pole of locus coeruleus which were labeled only by hypothalamic injections. This analysis of spatial organization within locus coeruleus is unique in its utilization of a defined control group, experimental groups consisting of strictly defined replications, accurate three-dimensional reconstruction, and statistical comparisons. The demonstrated spatial heterogeneity of locus coeruleus neurons with respect to efferent projections can now be compared to the spatial distributions of other cellular characteristics such as soma morphology, colocalized transmitters and physiological properties. Presumably, such spatial segregation reflects the operation of functionally important organizing principles within the nucleus.     

Norepinephrine innervation of the cochlear nuclei by locus coeruleus neurons in the rat

Summary The cochlear nuclei (CN) contain a moderate concentration of norepinephrine (445±20 ng/g tissue) with dopamine levels (46±14 ng/g) that are low and within the precursor range expected for a norepinephrine (NE) terminal system. Lesion and horseradish peroxidase (HRP) experiments indicate that this innervation is bilateral and arises from fusiform and multipolar neurons in the locus coeruleus.Autoradiographic and fluorescence histochemical experiments demonstrate that locus coeruleus fibers reach the ipsilateral ventral cochlear nuclei via a rostral pathway that projects from the rostral locus coeruleus laterally through the brain stem to the rostral tip of the ventral nuclei. This pathway is located dorsal to the motor and spinal trigeminal nuclei and ventral to the middle cerebellar peduncle. Descending coeruleo-cochlear fibers travel between the fourth ventricle and the vestibular nuclei to enter the acoustic striae. These fibers innervate both the dorsal and ventral nuclei. Contralateral locus fibers reach the CN by crossing in the pontine central gray at the rostral border of the fourth ventricle and by decussating with the fibers of the mesencephalic trigeminal nucleus ventral to the medial longitudinal fasciculus. The bilateral locus coeruleus innervation of the cochlear nuclei comprises a highly collateralized network of varicose axons which are not topographically organized. Unlike the cochlear nerve fibers in the CN which form specific projections, the locus coeruleus afferents to these sensory nuclei are diffuse and non-specific.     

Adrenergic innervation of the rat nucleus locus coeruleus arises predominantly from the C1 adrenergic cell group in the rostral medulla.

Focal iontophoretic injections of the retrograde tracer Fluoro-Gold into the locus coeruleus were combined with immunocytochemistry for phenylethanolamine N-methyltransferase, the final enzyme in the synthesis of epinephrine. Retrograde labeling confirmed recent findings that the major afferents to the locus coeruleus are present in the ventrolateral (nucleus paragigantocellularis) and dorsomedial medulla (nucleus prepositus hypoglossi), areas containing the C1 and C3 adrenergic cell groups, respectively. The Fluoro-Gold label revealed morphologic details of locus coeruleus afferent cells. Labeled neurons in the prepositus hypoglossi region were typically round (10 microns diameter) or ellipsoidal and compressed against the ventricle wall (10 x 20 microns), while those in the paragigantocellularis were most often multipolar and ellipsoidal or triangular in shape (10 x 20-20 x 30 microns). Double labeling in the same tissue sections revealed that locus coeruleus afferent neurons are intercalated among phenylethanolamine N-methyltransferase-positive C1 and C3 neurons. Twenty-one per cent of locus coeruleus afferent neurons in paragigantocellularis stained for phenylethanolamine N-methyltransferase while only 4% of locus coeruleus afferents in the prepositus hypoglossi area exhibited phenylethanolamine N-methyltransferase immunoreactivity. In paragigantocellularis, doubly labeled neurons were usually the smaller locus coeruleus afferents, while in the prepositus hypoglossi phenylethanolamine N-methyltransferase labeling was found in all cell types that project to the locus coeruleus. Phenylethanolamine N-methyltransferase-positive fibers from the C1 and C3 cell groups form an adrenergic fiber bundle in the dorsomedial medulla; in the pons, these fibers appear to exit this bundle and innervate the locus coeruleus. Fibers from the neurons of the C3 cell group also appear to ascend on the dorsal surface of the medulla to innervate the locus coeruleus. The phenylethanolamine N-methyltransferase fiber innervation in the locus coeruleus was dense and highly varicose. Phenylethanolamine N-methyltransferase innervation in the dorsal pons was not restricted to the locus coeruleus but was also prominent in neighboring areas such as Barrington's nucleus and the lateral dorsal tegmental nucleus of Gudden.     

Locus coeruleus neurons in the rat containing neuropeptide Y, tyrosine hydroxylase or galanin and their efferent projections to the spinal cord, cerebral cortex and hypothalamus

The efferent projections of locus coeruleus neurons which contain neuropeptide Y-, tyrosine hydroxylase- or galanin-like immunoreactivity were investigated using the indirect immunofluorescence technique combined with the retrograde transport of the fluorescent substance Fast Blue. Four groups of rats received injections of Fast Blue: (1) bilaterally into the mid-thoracic spinal cord (T6-T7); (2) unilaterally into the low cervical spinal cord (C4-C5); (3) unilaterally into the paraventricular, periventricular and dorsomedial hypothalamic nuclei; and (4) unilaterally into five sites in the cerebral cortex (frontal, cingulate and striate cortex). Efferent projections to the spinal cord, hypothalamus and cerebral cortex from neuropeptide Y-, tyrosine hydroxylase- and galanin-containing locus coeruleus cells were observed. A higher percentage of the peptidergic locus coeruleus neurons projected to the hypothalamus than to the spinal cord or cerebral cortex. The distribution and morphology of the neuropeptide Y- and galanin-containing neurons in the locus coeruleus were also investigated. Neuropeptide Y-like immunoreactivity and galanin-like immunoreactivity were found in small, medium and large multipolar neurons, as well as in fusiform locus coeruleus cells. The neuropeptide Y- and galanin-immunoreactive neurons were found throughout the locus coeruleus. In the caudal locus coeruleus, they were primarily located in the dorsal portion. Neuropeptide Y-like immunoreactivity and galanin-like immunoreactivity were only seen in a few tyrosine hydroxylase-positive neurons of the subcoeruleus group. The data show that the peptide-containing locus coeruleus neurons have efferent projections to the spinal cord, hypothalamus and cerebral cortex. The locus coeruleus may be divided into functional subdivisions dependent on the region of the locus coeruleus, the neurotransmitter/neuropeptide(s) contained within the neurons and their efferent projections.     

Distribution of gamma aminobutyric acid containing neurons and terminals in the septal area. An immunohistochemical study using antibodies to glutamic acid decarboxylase in the rat brain

The distribution of gamma aminobutyric acid (GABA)-containing neurons and nerve terminals was examined in the rat septal area by using specific antibodies to the enzyme glutamic acid decarboxylase (GAD) in combination with the avidin-biotin immunoperoxidase method. Whereas only a few GAD positive neurons were present in the septum of normal rats, the septal area of rats treated with colchicine, an inhibitor of fast axonal transport, showed numerous GAD-immunoreactive neurons. These neurons were evenly filled with GAD-immunoreactive material throughout the cytoplasm of the soma and proximal parts of the dendrites. Although GAD-positive neurons were present in most parts of the septal area, their density differed greatly in the different septal subnuclei. Both the diagonal band of Broca (vertical and horizontal parts) and the lateral septum were rich in GAD positive cell bodies, whereas the medial septal nucleus and the intermediate parts of the lateral septum contained relatively few. Within the lateral septum itself a larger number of labeled cell bodies was present in its ventral subdivision. The anterior hippocampal rudiment (taenia tecta) contained numerous GAD-positive neurons, while the septal component of the island of Calleja (insula magna) was devoid of them. GAD-immuno-positive neurons found within the septum ranged from small (15 microns) to large (30-35 micron). They were round or multipolar in the diagonal band, medium-sized multipolar in the lateral septum, and pyramidal, round or fusiform in the anterior hippocampal rudiment. GAD-immunoreactive nerve terminals are present in most subdivisions of the septal nuclei, with the exception of myelinated fiber tracts, and throughout all rostrocaudal levels of the septum. However, the density of the innervation is not the same within all individual nuclei. The lateral septum (dorsal and ventral parts) contained high density innervation but the diagonal band of Broca had a lower density of GAD-positive terminals. The lateral border of the islands of Calleja was rich in thick GAD-positive processes that appeared to be continuous with GAD-immunoreactive processes of the substantia inominata. The inner portion of the molecular layer adjacent to the granule cells of the anterior hippocampal rudiment contained a rich GAD-positive terminal field.     

Survival and growth of neurons with enkephalin-like immunoreactivity in fetal brain areas grafted to the anterior chamber of the eye

Areas of fetal rat brain and spinal cord known to contain enkephalin-like immunoreactive cell bodies and/or terminal fields were transplanted to the anterior chamber of the eye of adult rats. Enkephalin-like immunoreactive neurons survive and produce an enkephalin-like immunoreactive fiber network within grafts of spinal cord, ventral medulla oblongata, ventrolateral pons, tectum, locus coeruleus, substantia nigra and the areas containing columna fornicis and globus pallidus. Although single intraocular grafts of neocortex do not apparently contain enkephalin-like immunoreactive fibers, such grafts contain a variable amount of sparsely distributed enkephalin-like fibers when sequentially grafted in oculo with either locus coeruleus or spinal cord. Combinations of locus coeruleus and globus pallidus contained a rich enkephalin fiber network in the locus coeruleus part and a sparse innervation of the globus pallidus part.

We conclude that enkephalin-like immunoreactive neurons in small areas of fetal rat brain can be successfully transplanted to the anterior chamber of the eye. They are able to survive and develop to maturity in complete isolation from the rest of the brain. In general, the enkephalin-like immunoreactive fiber density in the various single grafts approximated that of their brain counterparts in situ. Fiber formation can be reinitiated in mature enkephalin-like immunoreactive neurons by addition of new brain target areas. Thus, the technique permits establishment of isolated, defined enkephalin systems and pathways accessible to functional analysis.     

人胎蓝斑神经元免疫组织化学研究

为了探讨人蓝斑神经元的胚胎发育特征 ,为蓝斑 -脊髓移植选择适宜胎龄提供形态学根据 ,本研究用免疫组织化学技术系统地观察了人胎蓝斑酪氨酸羟化酶样免疫反应阳性神经元的发育。结果证明 :( 1)蓝斑酪氨酸羟化酶样神经元在胎龄 4个月时已经出现在蓝斑的腹侧部 ;( 2 )蓝斑酪氨酸羟化酶样神经元随胎龄增长逐渐增多 ,以 5个月时增加显著 ;( 3)酪氨酸羟化酶样神经元的密度在胚胎早期升高 ,晚期呈下降趋势 ;( 4)酪氨酸羟化酶样神经元主要分布在蓝斑的背侧部 ,少量散在于腹侧部 ;( 5)酪氨酸羟化酶样神经元开始出现时呈圆形或卵圆形 ,5～ 6个月时呈锥形和梭形 ,7～ 8个月时则以梭形、多角形为主。其胞体逐渐增大 ,胞浆逐渐增多 ,核浆之比由大变小 ,胞突从粗短变为细长平滑。本研究结果提示 ,人胎蓝斑移植以 4个月胎龄者作移植供体较为适宜     

乙酰胆碱酯酶阳性神经元在鼠脑的分布和形态特征

本文用乙酰胆碱酯酶(AChE)再生技术,研究AChE阳性神经元在鼠脑的分布和形态特征。按其染色程度,可见强度、中度和轻度三种染色细胞。强染色细胞多数是较大的多极细胞,主要分布于纹状体、基底前脑、下丘脑、黑质、红核、蓝斑,腹侧被盖区、臂旁核、桥被盖核和脑神经运动核。本文将AChE染色结果和胆碱乙酰转移酶(ChAT)免疫组织化学资料进行了比较,对AChE和胆碱能神经元的关系,以及AChE阳性神经元的性质和意义,进行了讨论。     

The neurons and their postnatal development in the ventral lateral geniculate nucleus of the rat

Summary The morphology and distribution of neurons in the ventral lateral geniculate nucleus (vLGN) of adult rats, and the postnatal growth and differentiation of these neurons were studied in Golgi-Cox preparations.In the adult, two main cell classes were recognized: class A cells and class B cells. The former are assumed to be projection neurons. The latter closely resemble the class B cells of the dorsal lateral geniculate nucleus and are interpreted as presynaptic dendrite-bearing interneurons. Class A cells predominated and three subtypes were tentatively identified: small-medium size multipolar neurons, with short, branched spiny dendrites (most numerous in dorsolateral vLGN); medium-large fusiorm cells with one or two stem dendrites at each pole (most numerous in medial vLGN); large multipolar neurons with long, sparsely branched dendrites (most numerous in ventral vLGN).Class A and B cells were distinguishable at birth and showed parallel cell body size increases up to postnatal day 24. The dendrites of both classes of cell also reached the adult stage of differentiation at about day 24 but the differentiation of class B cell dendrites lags slightly behind that of class A cell dendrites.     

A study of the organization of the locus coeruleus projections to the lateral geniculate nuclei in the albino rat

The lateral geniculate nuclei of the rat are known to receive an innervation from catecholamine-containing neurons. In the present study the origin, axonal projections and terminal distribution of this innervation was studied. The lateral geniculate nuclei contain a356 ± 20 ng norepinephrine/g and64 ± 7 ng dopamine/g tissue; the latter is within the range expected for dopamine as a precursor in a region innervated by a norepinephrine-containing terminal system. When separate norepinephrine-containing cell groups located at various brain stem levels are ablated or their axonal projections destroyed, only lesions in the locus coeruleus produce a significant decrease in the norepinephrine content of the lateral geniculate nuclei. Injections of horseradish peroxidase into the lateral geniculate nuclei result in retrograde transport of horseradish peroxidase only to the noradrenergic neurons of the locus coeruleus. The labelled neurons are pretent throughout the rostrocaudal and dorsoventral axes of both the ipsilateral (60%) and contralateral (40%) nucleus. Autoradiographic and fluorescence histo-chemical experiments indicate that axons that ascend from the locus coeruleus reach the lateral geniculate nuclei via the dorsal tegmental catecholamine-containing bundle and the medial forebrain bundle. These fibers enter the ventral lateral geniculate nucleus from the zona incerta and the dorsal lateral geniculate nucleus from the superior thalamic radiation, thalamic reticular nucleus, and lateral posterior nucleus. Contralateral fibers from the locus coeruleus cross in the posterior commissure, supraoptic and pontine decussations and join the ipsilateral projections to the lateral geniculate nuclei. The bilateral locus coeruleus innervation of the nuclei is comprised of a highly branched network of varicose axons. Neither the ipsilateral nor the contralateral projections appear to be topographically organized; instead, a single fiber may have collateral axons that branch throughout large areas of the nuclei. This innervation is moderately dense in the ventral, and very dense in the dorsal, lateral geniculate nucleus.The study indicates that both the dorsal and ventral lateral geniculate nuclei receive a diffuse catecholamine-containing innervation which arises solely from the norepinephrine-containing neurons of the locus coeruleus. The innervation of each lateral geniculate nucleus is bilateral, with noradrenergic neurons located throughout both the ipsilateral and the contralateral locus coeruleus contributing to ascending pathways that terminate as a diffuse, plexiform innervation interspersed among other afferents to the lateral geniculate nuclei. It is speculated that such a diffuse noradrenergic innervation might depress the spontaneous activity of neurons in the lateral geniculate nuclei, while preserving or enhancing their responsiveness to afferent optic stimulation.     

Afferents to the basal forebrain cholinergic cell area from pontomesencephalic--catecholamine, serotonin, and acetylcholine--neurons

The afferent input to the basal forebrain cholinergic neurons from the pontomesencephalic tegmentum was examined by retrograde transport of wheatgerm agglutinin-horseradish peroxidase in combination with immunohistochemistry. Multiple tyrosine hydroxylase-, dopamine-beta-hydroxylase-, serotonin- and choline acetyltransferase-immunoreactive fibres were observed in the vicinity of the choline acetyltransferase-immunoreactive cell bodies within the globus pallidus, substantia innominata and magnocellular preoptic nucleus. Micro-injections of horseradish peroxidase-conjugated wheatgerm agglutinin into this area of cholinergic perikarya led to retrograde labelling of a large population of neurons within the pontomesencephalic tegmentum, which included cells in the ventral tegmental area, substantia nigra, retrorubral field, raphe nuclei, reticular formation, pedunculopontine tegmental nucleus, laterodorsal tegmental nucleus, parabrachial nuclei and locus coeruleus nucleus. Of the total population of retrogradely labelled neurons, a significant (approximately 25%) proportion were tyrosine hydroxylase-immunoreactive and found in the ventral tegmental area (A10), the substantia nigra (A9), the retrorubral field (A8), the raphe nuclei (dorsalis, linearis and interfascicularis) and the locus coeruleus nucleus (A6), Another important contingent (approximately 10%) was represented by serotonin neurons of the dorsal raphe nucleus (B7), the central superior nucleus (B8) and ventral tegmentum (B9). A small proportion (less than 1%) was represented by cholinergic neurons of the pedunculopontine (Ch5) and laterodorsal (Ch6) tegmental nuclei. These results demonstrate that pontomesencephalic monoamine neurons project in large numbers up to the basal forebrain cholinergic neurons and may represent a major component of the ventral tegmental pathway that forms the extra-thalamic relay from the brainstem through the basal forebrain to the cerebral cortex.     

Collateralized projections from neurons in the rostral medulla to the nucleus locus coeruleus, the nucleus of the solitary tract and the periaqueductal gray.

We have examined collateral projections of locus coeruleus afferent neurons in the rostral medulla to the caudal nucleus of the solitary tract or to the periaqueductal gray using double retrograde labeling techniques in the rat. The present findings confirm previously reported connections to the locus coeruleus, the nucleus of the solitary tract and the lateral periaqueductal gray from the nucleus paragigantocellularis in the rostral ventral medulla. Our results also reveal previously unreported projections from the rostral dorsomedial medulla (in a similar region as locus coeruleus-projecting neurons) to the lateral periaqueductal gray. Following retrograde tracer injections into the nucleus of the solitary tract and the locus coeruleus, doubly labeled neurons were seen in both the nucleus paragigantocellularis and in the rostral dorsomedial medulla. Cell counts revealed that approximately 25% of locus coeruleus-projecting neurons in the nucleus paragigantocellularis, and 12% in the dorsomedial medulla, also innervate the caudal nucleus of the solitary tract. In contrast, no doubly labeled neurons within the rostral ventral medulla were found following injections into the lateral periaqueductal gray and the locus coeruleus, although singly labeled neurons for the two tracers were interdigitated in some regions. Following these injections, numerous neurons were also retrogradely labeled in the dorsomedial medulla in the region of the medial prepositus hypoglossi and the perifascicular reticular formation. A small percentage of locus coeruleus afferents in the dorsal medulla (approximately 10%) also projected to the lateral periaqueductal gray. These results indicate that neurons in both the ventrolateral and dorsomedial rostral medulla frequently send collaterals to both the locus coeruleus and the caudal nucleus of the solitary tract. A small number of neurons in the dorsomedial medulla project to both the locus coeruleus and the lateral periaqueductal gray, but separate populations of neurons project to the locus coeruleus and the lateral periaqueductal gray from the ventrolateral medulla. These results functionally link the locus coeruleus and the nucleus of the solitary tract by virtue of common afferents, and support other studies indicating the importance of central autonomic circuitry in the afferent control of locus coeruleus neurons.     

体外长期培养大鼠中脑多巴胺神经元的形态学观察

本文研究了中脑多巴胺神经元在体外长期培养过程中的形态发育。动物选用胚胎14天SD大鼠,取中脑腹侧部制成细胞密度为2×10~5/ml的悬液,接种于24孔培养板中,培养1天至6周,以酪胺酸羟化酶免疫组化方法、单纯荧光组化方法和外源性儿茶酚胺荧光组化方法,观察中脑多巴胺神经元的体外长期培养发育状况。培养3天后多巴胺神经元已有单极或双极的突起发出,培养1周突起进一步伸长,并在沿途开始发出分支,有些末端见有生长锥。除散在分布的多巴胶神经元外,还能见到多巴胺神经元细胞群。培养2至3周,突起的分支增多,并明显出现念珠状膨大。在培养4-6周的标本中,仍可见到部分发育成熟的多巴胺神经元。多巴胺神经元在体外培养中的形态可分为二类,即梭形细胞和多极细胞。棱形细胞一般有两个突起,分别从胞体两极发出;多极细胞胞体呈圆形、多角形或三角形,可发出3-6个突起。实验结果表明多巴胺神经元的体外发育过程与在体相似。     

Cochlear nuclear complex of mice

Using serial sections stained with luxol fast blue-cresyl violet, the cochlear nuclei of CBA/J mice were parcellated into the same cytoarchitectonic areas and layers that Osen (1969) used in cats. Within the spherical cell areas, the distribution of Nissl substance is more reliable than soma shape in identifying the spherical cells. The area of large spherical cells is extremely small in CBA/J mice but does contain significantly larger neurons than the small spherical cell area. In Golgi preparations, bushy cells are found in all areas of the ventral cochlear nucleus except in the octopus cell area and granule cell layer. They are more numerous anteriorly than posteriorly and details of their morphology are quite variable. Stellate cells are found throughout the ventral cochlear nuclei but are present in greatest numbers in the multipolar cell area; they are rare in the large spherical cell area and octopus cell area. Because size, soma morphology, and dendritic arborization vary on a continuum rather than in discrete steps, we have not subcategorized these neurons. Octopus cells are restricted to the posterior, dorsomedial area of the ventral cochlear nucleus. In the central region of the dorsal cochlear nucleus, stellate cells abound and are categorized as vertical, elongate, or radiate cells. In the granule layer of the dorsal cochlear nucleus there are both fusiform and Purkinje-like neurons, so named because of their resemblance to cerebellar Purkinje cells. These Purkinje-like cells differ from fusiform cells in having (1) a smaller cell body, spherical in shape, (2) no basal dendrites, (3) a sagittal dendritic orientation, (4) elaborate dendritic branching, and (5) abundant dendritic spines.     

Corticotropin-releasing factor innervation of the locus coeruleus region: distribution of fibers and sources of input.

Electrophysiologic studies support the hypothesis that corticotropin-releasing factor, the neurohormone that initiates adrenocorticotropin release during stress, also serves as a neurotransmitter in the pontine noradrenergic nucleus, the locus coeruleus. To elucidate the circuitry underlying proposed corticotropin-releasing factor neurotransmission in the locus coeruleus, the present study utilized immunohistochemical techniques to characterize corticotropin-releasing factor innervation of rat locus coeruleus and pericoerulear regions. Corticotropin-releasing factor-like immunoreactive fibers were identified in the locus coeruleus of colchicine- and non-colchicine-treated rats. However, corticotropin-releasing factor innervation of pericoerulear regions rostral and lateral to the locus coeruleus was more dense than that of the locus coeruleus proper. Double-labeling studies utilizing antisera directed against corticotropin-releasing factor and tyrosine hydroxylase indicated that corticotropin-releasing factor-like immunoreactive fibers overlap with tyrosine hydroxylase-like immunoreactive processes of locus coeruleus neurons, particularly in rostral medial and lateral regions. A group of corticotropin-releasing factor-like immunoreactive neurons was localized just lateral to the locus coeruleus and numerous corticotropin-releasing factor-like immunoreactive neurons were visualized just ventral to the rostral pole of the locus coeruleus in a region corresponding to Barrington's nucleus. None of these corticotropin-releasing factor-like immunoreactive neurons were tyrosine hydroxylase-positive. To determine the source of corticotropin-releasing factor-like immunoreactive fibers in the locus coeruleus, injections of the retrograde tracer [wheat germ agglutinin conjugated to inactivated (apo) horseradish peroxidase coupled to gold particles] were made into the locus coeruleus and sections were processed for corticotropin-releasing factor-like immunoreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fine structure and neurotransmitter cytochemistry of neurons in the rat ventral cochlear nucleus projecting to the ipsilateral dorsal cochlear nucleus

The neural tracer wheat germ agglutinin conjugated to horse radish peroxidase was injected into the rat dorsal cochlear nucleus and acoustic stria. Some labelled neurons in the ipsilateral ventral cochlear nucleus were found as a result. These neurons were studied at the ultrastructural level, and their axo-somatic synaptic profile and glycine immunoreactivity were determined. Most neurons were glycine negative and classified as type I multipolar neurons. The latter showed a different synaptic profile from that of neurons projecting to the contralateral inferior colliculus or cochlear nucleus. This suggests the presence of differing populations of multipolar cells based on their synaptic profile. Few labelled multipolar neurons of type II were found, which appeared glycine negative and, rarely, glycine positive. The latter show an ultrastructure and axo-somatic profile similar to that of glycinergic commissural neurons in the dorsal and ventral cochlear nucleus. In particular, about one-third of boutons contained round synaptic vesicles, which are believed to contain an excitatory neurotransmitter. The ultrastructural analysis of the synaptic boutons in the cochlear nucleus confirms the presence of numerous cases of colocalization of glycine and GABA where flat and pleomorphic synaptic vesicles are mixed. The present study is in accordance with previous tract-tracing light microscopic studies which have indicated that large glycinergic neurons in the ventral cochlear nucleus act as broad-band inhibitory neurons in microcircuits of the dorsal cochlear nucleus and contralateral cochlear nucleus.     

大鼠终纹床核向结合臂旁核的投射 Ⅱ.HRP、FG逆行追踪研究

用HRP、荧光金逆行束路追踪技术对大鼠终纹床核向结合臂旁核的投射进行了研究。结果显示,投射至结合臂旁核的终纹床核神经元几乎全部位于终纹床核前部,后部罕见。在终纹床核前部中投射神经元位于前背区、前外侧区及前腹侧区,其中以前外侧区中的细胞数目最多。标记细胞主要出现于BST的卵圆核及其腹侧邻近区、菱形核、大细胞核和纹旁核等处。     

Ultrastructure and immunocytochemical characteristics of cells in the octopus cell area of the rat cochlear nucleus: comparison with multipolar cells

Cells in the octopus cell area of the rat ventral cochlear nucleus have been connected to the monaural interpretation of spectral patterns of sound such as those derived from speech. This is possible by their fast onset of firing after each octopus cell and its dendrites have been contacted by many auditory fibres carrying different frequencies. The cytological characteristics that make these large cells able to perform such a function have been studied with ultrastructural immunocytochemistry for glycine, GABA and glutamate, and compared to that of other multipolar neurons of other regions of the ventral cochlear nucleus. Cells in the octopus cell area have an ultrastructure similar to large-giant D-multipolar neurons present in other areas of the cochlear nucleus, from which they differ by the presence of a larger excitatory axo-somatic synaptic input and larger mitochondria. Octopus cells are glycine and GABA negative, and glutamate positive with different degree. Large octopus cells receive more axo-somatic boutons than smaller octopus cells. Fusiform octopus cells are found sparsely within the intermediate acoustic striae. These cells are large to giant excitatory neurons (23-35 microm) with 62-85% of their irregular perimeter covered with large axo-somatic synaptic boutons. Most boutons contain round vesicles and are glycine and GABA negative but glutamate positive. The latter excitatory boutons represent about 70% of the input to octopus cells. Glycine positive boutons with flat and pleomorphic vesicles account for 9-10% of the input while GABA-ergic boutons with pleomorphic vesicles represent about 20% of the synaptic input. Other few, multipolar cells within the rat octopus cell area are surrounded by more inhibitory than excitatory terminals which contain flat and pleomorphic vesicles, a feature distinctive from that of true octopus cells. The latter resemble multipolar cells seen outside the octopus cell area that project to the contralateral inferior colliculus and cochlear nucleus. Based on this study, two types of large multipolar cells are present in the octopus cell area: 1) those that receive about 70% of axo-somatic R boutons and stain more intensely for glutamate may correspond to pure onset neurons (Oi); 2) those with less than 33% of R axosomatic boutons, with less immunoreactivity to glutamate and sometimes glycine positive may represent the onset chopper neurons (Oc). In the octopus cell area the first type appears more prevalent. The present study suggests that octopus cells are a special type of excitatory D-multipolar neuron confined to the octopus cell area and mainly innervated by glutamatergic cochlear nerve terminals.     

Origin of the afferent connections to the parolfactory lobe in quail shown by retrograde labelling with a fluorescent neuron tracer

Summary Unilateral injection of Fast Blue retrograde fluorescent neuron tracer into the parolfactory lobe (POL) in the quail showed multiple innervation of this structure. Neurons projecting into the POL were located in three areas: 1) the telencephalon, where they were scattered in the paleostriatum, the archistriatum and ventral hyperstriatum, and among the fibers of different tracts including the anterior commissure, the occipito-mesencephalic tract and the fasciculus prosencephali lateralis; 2) the diencephalon, where fluorescent neurons with large multipolar perikarya were found in the dorsal thalamic wall; 3) the midbrain, where large perikarya were located in the ventralis area of Tsai, the locus coeruleus, the nucleus subcoeruleus, around the medial longitudinal fasciculus, in the substantia grisea centralis, the formatio reticularis mesencephali and among the fibers of the brachium conjunctivum. In most cases, axons innervating the POL ran parallel to the fibers of the medial forebrain bundle and contralateral to the perikarya from which they originated. This study also showed that the anterior and posterior parts of the POL received fibres from different sources.