Immunocytochemical localization of the glucose transporter 2 (GLUT2) in the adult rat brain. II. Electron microscopic study

Following a former immunohistochemical study in the rat brain [Arluison, M., Quignon, M., Nguyen, P., Thorens, B., Leloup, C., Penicaud, L. Distribution and anatomical localization of the glucose transporter 2 (GLUT2) in the adult rat brain. I. Immunohistochemical study. J. Chem. Neuroanat., in press], we have analyzed the ultrastructural localization of GLUT2 in representative and/or critical areas of the forebrain and hindbrain. In agreement with previous results, we observe few oligodendrocyte and astrocyte cell bodies discretely labeled for GLUT2 in large myelinated fibre bundles and most brain areas examined, whereas the reactive glial processes are more numerous and often localized in the vicinity of nerve terminals and/or dendrites or dendritic spines forming synaptic contacts. Only some of them appear closely bound to unlabeled nerve cell bodies and dendrites. Furthermore, the nerve cell bodies prominently immunostained for GLUT2 are scarce in the brain nuclei examined, whereas the labeled dendrites and dendritic spines are relatively numerous and frequently engaged in synaptic junctions. In conformity with the observation of GLUT2-immunoreactive rings at the periphery of numerous nerve cell bodies in various brain areas (see previous paper), we report here that some neuronal perikarya of the dorsal endopiriform nucleus/perirhinal cortex exhibit some patches of immunostaining just below the plasma membrane. However, the presence of many GLUT2-immunoreactive nerve terminals and/or astrocyte processes, some of them being occasionally attached to nerve cell bodies and dendrites, could also explain the pericellular labeling observed. The results here reported support the idea that GLUT2 may be expressed by some cerebral neurones possibly involved in glucose sensing, as previously discussed. However, it is also possible that this transporter participate in the regulation of neurotransmitter release and, perhaps, in the release of glucose by glial cells.     

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)     

Immunocytochemical evidence of vesicular localization of the orphan transporter RXT1 in the rat spinal cord.

Rxt1, a member of the Na+/Cl- orphan transporter family, exhibits numerous features suggesting a role as plasma membrane transporter. Despite numerous attempts, its substrate has not yet been identified, although immunocytochemical studies have shown that Rxt1 distribution generally matches that of glutamate or GABA. In order to further characterize Rxt1, its detailed immunocytochemical distribution in the rat spinal cord and dorsal root ganglia was studied at both light microscope and ultrastructural levels. The widespread distribution of Rxt1 in spinal cord and ganglia cannot be correlated with any known classical or peptidergic transmitter. Rxt1 is expressed in a subpopulation of glutamatergic primary afferent fibers, in large and medium-sized ganglion cells, while small glutamate cells exhibit generally no Rxt1-like immunoreactivity. In the spinal cord, Rxt1-immunoreactive cell body distribution is quite ubiquitous since Rxt1 is expressed in all laminae in various neuronal types like interneurons, some projection neurons and motoneurons. Some of these neurons are cholinergic. At the electron microscope level, the peroxidase labeling was never localized to the plasma membrane, but rather associated with different organelles including the outer membrane of small synaptic vesicles and large granular vesicles. This localization resembles that of vesicular transporters detected with the same method and suggests that Rxt1, in contrast to other Na+/Cl- transporters, is expressed on vesicles. This was confirmed using a pre-embedding silver-intensified colloidal gold method. Indeed, most gold particles appeared to be localized into the axoplasm on synaptic vesicle accumulations; only few gold particles were observed close to the plasma membrane. These results suggest that Rxt1, despite its molecular characteristics predicting a plasma membrane localization, might be a vesicular transporter.     

Topographical localization of glial cell line-derived neurotrophic factor in the human brain stem: an immunohistochemical study of prenatal, neonatal and adult brains

As a step towards the identification of the neuronal populations responsive to glial cell line-derived neurotrophic factor (GDNF) in the human nervous system and their changes with age, this study reports on the immunohistochemical localization of the protein GDNF in the autoptic normal human brain stem of pre- and full-term newborns and adult subjects. Two different anti-GDNF polyclonal antibodies were used. Western blot analysis on homogenates of human and rat brain and recombinant human GDNF resulted in differential detection of monomeric and dimeric forms of the proteins. The ABC immunohistochemical technique on cryostat tissue sections showed an uneven distribution of GDNF-like immunoreactive nerve fibers and terminals and neuronal cell bodies. Immunoreactive elements were mainly localized to the spinal trigeminal, cuneate, solitary, vestibular, and cochlear sensory nuclei, dorsal motor nucleus of the vagus nerve, ventral grey column, hypoglossal nucleus, dorsal and ventrolateral medullary reticular formation, pontine subventricular grey and locus coeruleus, lateral regions of the rostral pontine tegmentum, tectal plate, trochlear nucleus, dorsal and median raphe nuclei, caudal and rostral linear nuclei, cuneiform nucleus, and substantia nigra. Comparison between pre- and full-term newborns and adult subjects revealed changes with age in density of positive innervation and frequency of immunoreactive perikarya. The results obtained provide detailed information on the occurrence of GDNF-like immunoreactive neurons in the human brain stem and suggest that the protein is present in a variety of neuronal systems, which subserve different functional activities, at developmental ages and in adult brains.     

大鼠运动核内5-羟色胺1A、2A、5A受体的定位分布

为了阐明５ 羟色胺在中枢神经系统内与运动神经元结合的精确部位,本研究用免疫细胞化学技术分别观察了大鼠躯体运动核和内脏运动核内５ 羟色胺１Ａ、２Ａ、５Ａ 受体的定位分布。在躯体运动核内观察到：（１）５ 羟色胺１Ａ 受体样阳性神经元和纤维主要分布于动眼神经核、滑车神经核、三叉神经运动核、面神经核、舌下神经核和脊髓前角;（２）５ 羟色胺２Ａ 受体样阳性神经元主要见于动眼神经核、三叉神经运动核、面神经核、舌下神经核和脊髓前角,但阳性纤维和终末却密集地分布于三叉神经运动核、面神经核、舌下神经核和脊髓前角等处,除此之外动眼神经核、滑车神经核、展神经核和疑核内也能见到中等密度的阳性纤维和终末,纤维和终末的分布范围和染色浓度、密度都较神经元为明显;（３）少量淡染的５ 羟色胺５Ａ 受体样阳性神经元和稀疏的阳性纤维及终末主要见于三叉神经运动核、面神经核、舌下神经核和脊髓前角。在内脏运动核内观察的结果是：（１）动眼神经副交感核（Ｅ Ｗ 核）、上涎核、迷走神经背核、骶髓副交感核和胸髓侧角内仅有少量５ 羟色胺１Ａ 受体样阳性神经元、纤维和终末分布;（２）５ 羟色胺２Ａ 受体样阳性神经元和较密集的阳性纤维和终末见于Ｅ Ｗ 核、迷走神经背核、骶?     

Mapping of serotonin transporter messenger RNA-containing nerve cell populations in the cat brainstem

The anatomical distribution of nerve cells populations expressing serotonin transporter messenger RNA was investigated in the cat brain by means of in situ hybridization histochemistry. Formalin fixed coronal sections were hybridized with [³⁵S]dATP 3′ end-labeled oligoprobes complementary to three nucleotide sequences taken from the human and serotonin transporter. A strong hybridization signal was found in nerve cells populations exclusively localized within the brainstem. These positive cells mainly resided in the nuclei of the raphe, especially in the nuclei of the raphe dorsalis and raphe centralis superior. A small number of labeled cells was also observed in various areas including the dorsal part of the interpeduncular nucleus, in the midbrain, and the region ventrolateral to the inferior olive, the ventral midline and around the central canal, in the medulla oblongata. Overall, these data agree with the notion that in the cat, as previously suggested in the human and in the rat brain, the serotonin membrane transporter messenger RNA is predominantly expressed in areas known to contain serotonergic cell bodies.     

大鼠三叉神经感觉核簇内SP受体及三叉神经节内SP样阳性终末和SP受体分布的免疫组织化学研究

本文用免疫组织化学方法对三叉神经感觉核簇内的SP受体及三叉神经节内的SP样阳性终末和SP受体的分布状态进行了研究。三叉神经感觉主核内的SP受体样阳性胞体和树突主要见于其背侧部和腹侧部。三叉神经脊束核的各亚核内均可见到SP受体样阳性的结构:吻侧亚核的SP受体样阳性胞体和树突主要见于其中央部;极间亚核的周边部仅有少量SP受体样阳性的胞体和树突;尾侧亚核内SP受体样阳性的胞体和树突最密集,且主要位于Ⅰ、Ⅱ层。三叉神经节内可见SP样阳性终末呈丛状或环状包绕在阴性胞体周围,也可见到少量散在的SP受体样阳性的胞体。SP受体样免疫反应阳性产物位于阳性胞体和树突的膜上。     

Immunocytochemistry of B-50 (GAP-43) in the spinal cord and in dorsal root ganglia of the adult cat

Summary The distribution of the neural-specific growth associated protein B-50 (GAP-43), which persists in the mature spinal cord and dorsal root ganglia, has been studied by light and electron microscopic immunohistochemistry in the cat. Throughout the spinal cord, B-50 immunoreactivity was seen confined to the neuropil, whereas neuronal cell bodies were unreactive. The most conspicuous immunostaining was observed in the dorsal horn, where it gradually decreased from superficial laminae (I–II) toward more ventral laminae (III–V), and in the central portion of the intermediate gray (mainly lamina X). In these regions, the labelling was localized within unmyelinated, small diameter nerve fibres and axon terminals. In the rest of the intermediate zone (laminae VI–VIII), B-50 immunoreactivity was virtually absent. The intermediolateral nucleus in the thoracic and cranial lumbar cord showed a circumscribed intense B-50 immunoreactivity brought about by the labelling of many axon terminals on preganglionic sympathetic neurons. In motor nuclei of the ventral horn (lamina IX), low levels of B-50 immunoreactivity were present in a few axon terminals on dendritic and somal profiles of motoneurons. In dorsal root ganglia, B-50 immunoreactivity was mainly localized in the cell bodies of small and medium-sized sensory neurons. The selective distribution of persisting B-50 immunoreactivity in the mature cat throughout sensory, motor, and autonomie areas of the spinal cord and in dorsal root ganglia suggests that B-50-positive systems retain in adult life the capacity for structural and functional plasticity.     

Immunohistochemical localization of the vesicular glutamate transporter VGLUT2 in the developing and adult mouse claustrum

We studied the immunoreactive expression pattern for the vesicular glutamate transporter VGLUT2 in the embryonic, postnatal and adult mouse dorsal claustrum, at the light and electron microscopic levels. VGLUT2 immunoreactivity in the dorsal claustrum starts to be observed at E16.5, with a dramatic increase towards P0. At this age, abundant VGLUT2-immunoreactive axons and puncta are observed in all pallial regions, including the claustral complex. From the first postnatal week, VGLUT2 immunoreactivity declines in several telencephalic areas, including the pallium, but abundant VGLUT2-immunoreactive fine axons and puncta remain in the claustrum. Beginning at E18.5, VGLUT2 immunoreactivity within the claustrum shows a characteristic arrangement: a central part of the region is practically devoid of VGLUT2 immunoreactivity, and it is surrounded by plenty of immunoreactive axon terminals forming a shell around it. This core/shell arrangement of the VGLUT2 immunoreactivity resembles the complementary expression of parvalbumin and calretinin described in the mouse claustrum [Real, M.A., Dávila, J.C., Guirado, S., 2003. Expression of calcium-binding proteins in the mouse claustrum. J. Chem. Neuroanat. 25, 151-160]. We observed immunoreactive neuronal cell bodies as well in the dorsal claustrum, but only at P0. Electron microscopic analysis reveals that VGLUT2 immunoreactivity in the developing and adult dorsal claustrum consists predominantly of presynaptic boutons making asymmetric synaptic contacts. These VGLUT2-immunoreactive boutons are observed as early as E16.5 and may be related to thalamo-claustral incoming fibers.     

Distinct Localization of Peripheral and Central Types of Choline Acetyltransferase in the Rat Cochlea

We previously discovered a splice variant of choline acetyltransferase (ChAT) mRNA, and designated the variant protein pChAT because of its preferential expression in peripheral neuronal structures. In this study, we examined the immunohistochemical localization of pChAT in rat cochlea and compared the distribution pattern to those of common ChAT (cChAT) and acetylcholinesterase. Some neuronal cell bodies and fibers in the spiral ganglia showed immunoreactivity for pChAT, predominantly the small spiral ganglion cells, indicating outer hair cell type II neurons. In contrast, cChAT- and acetylcholinesterase-positive structures were localized to fibers and not apparent in ganglion cells. After ablation of the cochlear nuclei, many pChAT-positive cochlear nerve fibers became clearly visible, whereas fibers immunopositive for cChAT and acetylcholine esterase disappeared. These results suggested that pChAT and cChAT are localized in different systems of the rat cochlea; pChAT in the afferent and cChAT in the efferent structures.     

Pre- and postsynaptic localization of GABA(B) receptors in the basal ganglia in monkeys

GABAergic neurotransmission involves ionotropic GABA(A) and metabotropic GABA(B) receptor subtypes. Although fast inhibitory transmission through GABA(A) receptors activation is commonly found in the basal ganglia, the functions as well as the cellular and subcellular localization of GABA(B) receptors are still poorly known. Polyclonal antibodies that specifically recognize the GABA(B)R1 receptor subunit were produced and used for immunocytochemical localization of these receptors at the light and electron microscope levels in the monkey basal ganglia. Western blot analysis of monkey brain homogenates revealed that these antibodies reacted specifically with two native proteins corresponding to the size of the two splice variants GABA(B)R1a and GABA(B)R1b. Preadsorption of the purified antiserum with synthetic peptides demonstrated that these antibodies recognize specifically GABA(B)R1 receptors with no cross-reactivity with GABA(B)R2 receptors. Overall, the distribution of GABA(B)R1 immunoreactivity throughout the monkey brain correlates with previous GABA(B) ligand binding studies and in situ hybridization data as well as with recent immunocytochemical studies in rodents. GABA(B)R1-immunoreactive cell bodies were found in all basal ganglia nuclei but the intensity of immunostaining varied among neuronal populations in each nucleus. In the striatum, interneurons were more strongly stained than medium-sized projection neurons while in the substantia nigra, dopaminergic neurons of the pars compacta were much more intensely labeled than GABAergic neurons of the pars reticulata. In the subthalamic nucleus, clear immunonegative neuronal perikarya were intermingled with numerous GABA(B)R1-immunoreactive cells. Moderate GABA(B)R1 immunoreactivity was observed in neuronal perikarya and dendritic processes throughout the external and internal pallidal segments. At the electron microscope level, GABA(B)R1 immunoreactivity was commonly found in neuronal cell bodies and dendrites in every basal ganglia nuclei. Many dendritic spines also displayed GABA(B)R1 immunoreactivity in the striatum. In addition to strong postsynaptic labeling, GABA(B)R1-immunoreactive preterminal axonal segments and axon terminals were frequently encountered throughout the basal ganglia components. The majority of labeled terminals displayed the ultrastructural features of glutamatergic boutons and formed asymmetric synapses. In the striatum, GABA(B)R1-containing boutons resembled terminals of cortical origin, while in the globus pallidus and substantia nigra, subthalamic-like terminals were labeled. Overall, these findings demonstrate that GABA(B) receptors are widely distributed and located to subserve both pre- and postsynaptic roles in controlling synaptic transmission in the primate basal ganglia.     

Ultrastructural study of the nerve plexus accompanying the ovarian artery and vein in the rat

The ultrastructural characteristics of the nerve plexus that accompanies the ovarian vessels of the rat were studied. The nerve fibers were primarily unmyelinated with less than 5% myelinated. Two types of neuronal cell bodies were found along these nerves. They were located at variable distances along the nerve bundle. The first and more numerous was a larger cell type similar to the autonomic postganglionic neuron. The second and smaller cell type had granulated vesicles throughout the cytoplasm. Synapses of the axodendritic type and synapses between the neuronal cell bodies were found. Most of the synapses possessed agranular vesicles. The presence of neuronal cell bodies is an important characteristic to consider in evaluating denervation of the ovary by interruption of this nerve plexus.     

Histamine-immunoreactive nerve fibers in the rat brain

A new immunohistochemical method that utilizes carbodiimide as a tissue fixative was applied to study the distribution of histamine-immunoreactive neuronal fibers and terminals in the rat brain. Immunoreactive fibers were observed in almost all major regions of the brain. They were most numerous in the different hypothalamic nuclei. Dense networks of immunoreactive fibers were also seen in the medial septum, nucleus of the diagonal band and ventral tegmental area. A moderate density of fibers was seen throughout the cerebral cortex, in some parts of the olfactory bulb and tubercle, bed nucleus of the stria terminalis, amygdala, basal parts of the hippocampus, inferior and superior colliculi, substantia nigra, lateral and medial parabrachial nucleus, and the nucleus of the solitary tract. Few histamine-immunoreactive fibers were seen in most parts of the caudate putamen, most thalamic nuclei, most pontine and ventral medullary nuclei. Histamine-immunoreactive neuronal cell bodies were found exclusively in the tuberomammillary nucleus, in agreement with previous reports. The results provide evidence for a widespread distribution of histamine-containing nerve fibers and terminals in the rat brain. Although immunohistochemical localization of histamine does not give direct evidence of a functional role of histamine in any brain area, this distribution suggests involvement in functions of the limbic system including the septal nuclei, hypothalamus and amygdala. The relatively dense histamine-immunoreactive fiber networks in the colliculi and dorsal cochlear nucleus indicate that this amine may play a role in visual functions and hearing. The paucity of immunoreactive fibers in the pontine and medullary areas suggests that the caudal projections originating from the tuberomammillary complex are minor ones compared to the major rostral projections. Several fiber projections originating from the tuberomammillary complex could be deduced from serial frontal, sagittal and horizontal sections. They contained fibers that crossed the midline at several levels of the brain. The results provide information on the target areas of the histaminergic neurons and form a basis for the examination of cellular contracts between the histaminergic neurons and other cells.     

A Golgi and electron microscope study of the ventral septum in the reptile, Podarcis hispánica

The ventral septum of the reptile Podarcis hispánica has been studied using cytoarchitectonical and Golgi methods as well as electron microscopy techniques. The ventral septum is located in the medial wall of the telencephalon, just ventral to the dorsal septum. 2 different cell masses or nuclei can be easily appreciated in this structure: the Ventro-lateral Nucleus, located close to the ventricle, and the Ventro-medial Nucleus, located close to the medial hemispheric wall. Using Golgi methods, 3 classes of neurons have been distinguished: Big Polymorphic (BP) neurons, Small Polymorphic (SP) neurons and Horizontal (H) neurons. BP neurons are located within Ventro-medial Nucleus and they are characterized by a large dendritic 3 with numerous dendritic spines (50 spines per 100 microns). SP neurons are located within Ventro-lateral Nucleus and they are characterized by a small dendritic tree which is covered by numerous dendritic spines (48 spines per 100 microns). H neurons are located around both nuclei and they are characterized by a linear dendritic tree and a low number of dendritic spines. Using E.M. techniques 3 classes of neuronal cell bodies can be distinguished: big neuronal somata, small neuronal somata and spindle-like neuronal somata Big somata are located within Ventro-medial Nucleus. Small somata are located within Ventro-lateral Nucleus. Spindle-like somata are located either close to the lateral ventricle or close to the medial hemispheric wall. We have identified 4 different types of synaptic endings in the neuropil, depending on the vesicle morphology: A) endings with slightly pleomorphic vesicles; B) endings with big round vesicles; C) endings with dense core vesicles and D) endings with small round vesicles.     

Parvalbumin and calbindin in the rat claustrum: An immunocytochemical study combined with retrograde tracing from frontoparietal cortex

The distribution of the calcium binding proteins parvalbumin and calbindin D-28k was examined in the claustrum of the rat by means of immunohistochemistry. The two proteins displayed a different and largely complementary pattern of distribution. Parvalbumin-immunostaining was intense in the neuropil of the dorsal claustrum and virtually absent in the neuropil of the ventral claustrum; parvalbumin-immunoreactive neuronal cell bodies were relatively numerous in the dorsal claustrum and were detected only occasionally in the ventral region. On the other hand, calbindin-immunostaining was prevalent in the ventral claustrum; very few calbindin-positive neurons were seen in the dorsal sector of the nucleus, whereas they were relatively more numerous in the ventral claustrum. The cell bodies of the majority of the claustral parvalbumin- or calbindin-immunoreactive neurons were oval or round, but immunostained polymorphous neurons were also observed. The surface of the immunopositive dendritic branches was smooth, with no evidence of spines.

Fluorescent retrograde tracing was combined with immunohistofluorescence to determine whether the parvalbumin-containing claustral cells project to the frontoparietal cortex. Neurons labelled after large fluorogold injections in frontoparietal cortical fields were highly intermingled in the dorsal claustrum with parvalbumin-immunoreactive cells but the two neuronal populations were separate. These data show that parvalbumin-immunoreactive claustral neurons do not project to the frontoparietal cortex. In addition, although these cells may project to other cortical or subcortical targets, the present findings suggest that they may represent, at least in part, local circuit claustral neurons, corresponding to the aspiny intrinsic neurons described in the rat claustrum in studies based on Golgi impregnation.     

Expression of vesicular glutamate transporters 1 and 2 in the cells of origin of the rat thalamostriatal pathway

The present study is focused on the analysis of the vesicular glutamate transporters 1 and 2 (VGLUT1 and VGLUT2) used by thalamic neurons giving rise to the thalamostriatal system. Instead of studying the distribution of VGLUT proteins at the level of thalamostriatal terminals, this report is focused on identifying the expression of the VGLUT mRNAs within the parent cell bodies of thalamic neurons innervating the striatum. For this purpose, we have combined dual in situ hybridization to detect both VGLUT1 and VGLUT2 mRNAs together with retrograde tracing with cholera toxin. Our results show that VGLUT2 is the only vesicular glutamate transporter expressed in thalamostriatal-projecting neurons located in the midline and intralaminar nuclei, whereas all neurons from the ventral thalamic nuclei innervating the striatum express both VGLUTs, at least at the mRNA level. Indeed, the mRNAs encoding for VGLUT1 and VGLUT2 displayed a sharp complementary subcellular distribution within neurons from the ventral thalamic nuclei giving rise to thalamostriatal projections. The differential distribution of VGLUT mRNAs lead us to conclude that the thalamostriatal pathway is a dual system, composed by a preponderant projection arising from the midline and intralaminar nuclei using VGLUT2 as the glutamate transporter, together with another important source of striatal afferents arising from neurons in the ventral thalamic relay nuclei containing both kinds of vesicular glutamate transporters.     

The auditory brainstem nuclei and some of their projections to the inferior colliculus in the North American opossum

Afferent projections to the inferior colliculus in the North American opossum have been examined using the retrograde transport of horseradish peroxidase. Projections to primarily the contralateral inferior colliculus arise in the dorsal and ventral cochlear nuclei, the auditory nerve nucleus and the spinal trigeminal nucleus pars caudalis, while ipsilateral projections arise in the superior paraolivary nucleus, the ventral nucleus of the trapezoid body, the ventral nucleus of the lateral lemniscus, the paralemniscal nucleus, the deep layer of the superior colliculus and the parabrachial nucleus. Bilateral projections to the inferior colliculus originate within the dorsal column nuclei, the nucleus reticularis gigantocellularis pars ventralis, the lateral and medial superior olivary nuclei, the dorsal nucleus of the lateral lemniscus and the auditory cortex. Nissl, fiber and Golgi-stained preparations were used to study the neuronal organization of those auditory nuclei with projections to the inferior colliculus. Anterograde axonal degeneration and transport techniques revealed that the inferior colliculus is innervated differentially by the dorsal and ventral cochlear nucleus, the superior olivary complex and the auditory neocortex. Axons from the contralateral dorsal cochlear nucleus and the ipsilateral superior olivary complex innervate both the central nucleus and external cortex, whereas those from ventral cochlear nucleus and contralateral, superior olivary complex project to only the central nucleus. Projections from auditory cortex form the complement of those from the cochlear nuclei and superior olivary complex, that is, they terminate in a thin band overlying the dorsal cortex and the superficial layer of external cortex.

Our results have been compared with those obtained from eutherian mammals and it is clear that there are striking similarities in neuronal organization and connectivity. Since the opossum is born 12 days after conception and has an extended development in an external pouch, it may be suited for developmental studies of the mammalian auditory connections and the behaviors dependent of them.     

Immunocytochemical mapping of NPY and VIP neuronal elements in the cat subcortical visual nuclei, with special reference to the pretectum and accessory optic system

The aim of this study was to describe the distribution patterns of neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP)-immunoreactive (ir) neuronal elements in subcortical visual centers of the cat. Numerous NPY-ir neurons were present in the feline nucleus of the optic tract and in the anterior pretectal nucleus. Only a few NPY-ir neurons were found in the posterior, medial and olivary pretectal nuclei and in the accessory optic nuclei. Diffuse and heavily beaded NPY-ir fiber plexuses were observed throughout the superior colliculus, pretectum, and accessory optic system. Extensively arborising NPY-ir fibers were present in the mesencephalon and ventral lateral geniculate nucleus, while the dorsal visual thalamic nuclei contained only a few NPY-ir fibers. VIP-ir cells were present mainly in the accessory optic nuclei, and they were absent in the dorsal visual thalamus. Both NPY- and VIP-ir neurons were multipolar and fusiform in shape in the regions studied. Enucleation did not alter the appearance of NPY- and VIP-containing neuronal elements in the superior colliculus and pretectum while in the thalamus a subset of NPY-ir fiber population disappeared, indicating their retinal origin. Although there is a partial overlap in the topographical localization of the NPY- and VIP-ergic neurons in the pretectum, the colocalization of the two peptides could not be demonstrated. The present observations demonstrate the existence of two different and separate peptidergic (NPY and VIP) neuronal populations in the pretectum. Accepted: 18 May 1999     

Localization of protein kinase C-beta-like immunoreactivity in the rat dorsal root ganglion

The localization of protein kinase C-beta-like immunoreactivity (PKC-beta-LI) was studied in the rat dorsal root ganglion (DRG) using an antibody specific for a peptide sequence common to the beta 1- and beta 2-subtypes. PKC-beta-LI was seen in 45% of neuronal cell bodies and in nerve fibers, which were mostly myelinated. The PKC-beta-LI-containing cell bodies had a diameter significantly larger than the unlabeled cell bodies. The results suggest that PKC-beta is a PKC subtype involved in cell surface signal transduction in the subpopulation of large DRG neurons.