Distribution of nerve growth factor receptor-like immunoreactivity in the adult rat central nervous system. Effect of colchicine and correlation with the cholinergic system--II. Brainstem, cerebellum and spinal cord

Multiple nuclei and fiber tracts in the adult rat brainstem and spinal cord were found to contain nerve growth factor receptor-related protein, as recognized by the monoclonal antibody 192-IgG. Both cholinergic and non-cholinergic sensory and motor regions demonstrated immunoreactive cell bodies and fibers. Nerve growth factor receptor-immunoreactive cells were seen in the mesencephalic nucleus of trigeminal nerve, superior colliculus, parabrachial, prepositus hypoglossal, raphe, dorsal and ventral cochlear, interstitial nucleus of the vestibular nerve, ambiguus and reticular nuclei, cerebellum and ventral spinal cord. Immunoreactive cells resembling neuroglia were distributed subpially along the superior colliculus. Intracerebroventricular injection of colchicine resulted in significantly increased nerve growth factor receptor immunoreactivity in all previously positive neurons and especially in certain neurons of the cochlear and ambiguus nuclei. It also resulted in the visualization of receptor immunoreactivity in certain neurons which were normally non-immunoreactive including cerebellar Purkinje cells, neurons of the central gray, locus coeruleus, facial, dorsal motor vagal and hypoglossal nuclei. In normal animals, nerve growth factor receptor-immunoreactive fibers and varicosities occurred in the trigeminal nerve nuclei, pontine, vestibular, parabrachial, facial, hypoglossal, dorsal motor vagal, solitary, gracile and cuneate nuclei and spinal cord. Although most fiber-like immunoreactive structures were probably axons and nerve terminals, neuroglial or extracellular localizations could not be excluded in some areas. For example, the medial nucleus of the inferior olive and most cerebellar nuclei contained diffuse non-fibrillar receptor immunoreactivity. The presence of nerve growth factor receptor-like immunoreactivity in cell bodies and fibers of several sensory and motor areas of the adult rat brainstem, cerebellum and spinal cord suggests multifocal actions of nerve growth factor or a nerve growth factor-like substance. Although the degree of overlap between nerve growth factor receptor- and choline acetyltransferase-containing regions in the brainstem is not as great as in the forebrain, our findings suggest a potential influence of nerve growth factor or nerve growth factor-like substances on cholinergic systems outside the forebrain. Furthermore, the disparities which occur imply that non-cholinergic nerve growth factor receptor-containing neurons of the brainstem, cerebellum and spinal cord may be affected by such trophic substances.     

Somatostatin and leu-enkephalin in the rat auditory brainstem during fetal and postnatal development

A transient expression of the neuropeptide somatostatin has been described in several brain areas during early ontogeny and several opioid peptides, such as leu-enkephalin, have also been found in the brain at this stage in development. It is therefore believed that somatostatin and leu-enkephalin may play a role in neural maturation. The aim of the present study was to describe the spatiotemporal pattern of somatostain and leu-enkephalin immunoreactivity in the auditory brainstem nuclei of the developing rat and to correlate it with other developmental events. In order to achieve this goal, we applied peroxidase-antiperoxidase immunocytochemistry to rat brains between embryonic day (E) 17 and adulthood. Somatostatin immunoreactivity (SIR) was found in all nuclei of the auditory brainstem, yet it was temporally restricted in most nuclei. SIR appeared prenatally and reached maximum levels around postnatal day (P) 7, when great numbers of immunoreactive neurons were present in the ventral cochlear nucleus (VCN) and in the lateral lemniscus. At that time relatively low numbers of cells were labeled in the dorsal cochlear nucleus, the lateral superior olive (LSO), and the inferior colliculus (IC). During the same period, when somata in the VCN were somatostatin-immunoreactive (SIR), a dense network of labeled fibers was also present in the LSO, the medial superior olive (MSO), and the medial nucleus of the trapezoid body (MNTB). As these nuclei receive direct input from VCN neurons, and as the distribution and morphology of the somatostatinergic fibers in the superior olivary complex (SOC) was like that of axons from VCN neurons, these findings suggest a transient somatostatinergic connection within the auditory system. Aside from the LSO, MSO, and MNTB, labeled fibers were found to a smaller extent in all other auditory brainstem nuclei. After P7, the SIR decreased and only a few immunoreactive elements were found in the adult auditory brainstem nuclei, indicating that somatostatin is transiently expressed in the rat auditory brainstem. Leu-enkephalin immunoreactivity showed a lower number and weaker intensity of labeled structures as compared to SIR, with E18 being the earliest day at which labeled fibers appeared in the SOC. At birth, immunoreactive fibers were also present in the cochlear nuclear complex and in the IC. Leu-enkephalin immunoreactive somata were found only after P12 in the CN and after P16 in the IC. Leu-enkephalin immunoreactivity was not transient, but increased progressively with age until about P21, when the adult levels were reached. Our results demonstrate somatostatinergic and leu-enkephalinergic inputs onto auditory brainstem neurons during perinatal life, i.e., during a period when the processes of synapse maturation occur. It is thus likely that both neuropeptides may influence the development of synaptic connections in the auditory brainstem.     

Localization of neurons containing immunoreactive delta sleep-inducing peptide in the rat brain: An immunocytochemical study

Delta sleep-inducing peptide has been found in the peripheral circulation of animals entering slow-wave, or delta, sleep. An antiserum to this peptide was used to localize immunoreactive-like delta sleep-inducing peptide in the rat brain. The peptide was shown to have a rather widespread distribution. In the forebrain, the majority of these neurons were found to extend in a continuous rostral-caudal band in the ventral one-third of the brain from the primary olfactory cortex to the lateral hypothalamus. Neurons were also present in the basal ganglia, amygdala, septum, and thalamus. In the brainstem, the neurons were widespread and associated with the reticular formation, raphe nuclei, nuclei of the trigeminal complex, several auditory nuclei—nuclei of the lateral lemniscus, cochlear nuclei, and inferior colliculus—, cerebellum, locus ceruleus, periventricular gray, and vagal and hypoglossal nuclei. Immunoreactive fibers were, in general, difficult to demonstrate; they were seen mainly in the vicinity of the third ventricle and near blood vessels.The function of delta sleep-inducing peptide is unknown and its role in sleep is still under investigation. The distribution of delta sleep-inducing peptide in the present study suggests that the peptide is a component of several systems—arousal, locomotion, auditory, visual and sensory—both somatic and vestibular. The widespread distribution of the peptide, the lack of demonstrable immunoreactive fiber tracts, and the presence of these neurons in areas known to contain aminergic and peptidergic neurons, raises the possibility that neurons containing delta sleep-inducing peptide may exert their effect by projecting directly into blood vessels and/or interacting with neurons in their immediate vicinity.     

Pathways and terminations of axons arising in the fastigial oculomotor region of macaque monkeys.

The majority of axons from the fastigial oculomotor region (FOR) decussated in the cerebellum at all rostrocaudal levels of the fastigial nucleus (FN) and entered the brainstem via the contralateral uncinate fasciculus (UF). Some decussated axons separated from the UF and ran medial to the contralateral superior cerebellar peduncle and ascended to the midbrain. Uncrossed FOR axons advanced rostrolaterally in the ipsilateral FN and entered the brainstem via the juxtarestiform body. The decussated fibers terminated in the brainstem nuclei that are implicated in the control of saccadic eye movements. In the midbrain, labeled terminals were found in the rostral interstitial nucleus of the medial longitudinal fasciculus, a medial part of Forel's H-field, the periaqueductal gray, the posterior commissure nucleus, and the superior colliculus of the contralateral side. In the pons and medulla, FOR fibers terminated in a caudal part of the pontine raphe, the paramedian pontine reticular formation, the nucleus reticularis tegmenti pontis, the dorsomedial pontine nucleus of the contralateral side, and the dorsomedial medullary reticular formation of both sides. In contrast, FOR projections to the vestibular complex were bilateral and were mainly to the ventral portions of the lateral and inferior vestibular nuclei. No labeled terminals were found in the following brainstem nuclei which are considered to be involved in oculomotor function: oculomotor and trochlear nuclei, interstitial nucleus of Cajal, medial and superior vestibular nuclei, periphypoglossal nuclei, and dorsolateral pontine nucleus. Labeling appeared in the red nucleus only when HRP encroached upon the posterior interposed nucleus.     

胆碱能神经成分在猫下脑干感觉系统中的分布

本文用avidin—biotin免疫细胞化学方法和AEC呈色法对ChAT样神经元胞体和纤维在猫下脑干各感觉系统的分布进行了观察。在薄束核、楔束核、外侧楔核和三叉神经感觉核群发现丰富的ChAT样阳性纤维;在三叉神经脊束核尾侧亚核深层偶见ChAT样阳性胞体。孤束核内有少量散在的ChAT样胞体和纤维;而臂旁核则存在丰富的ChAT样阳性胞体。在上橄榄核、斜方体核、外侧丘系核、前庭内侧核和前庭上核观察到多少不等的ChAT样阳性胞体和纤维;在耳蜗核、下丘见到较多的ChAT样纤维。二叠体旁核有大量的ChAT样胞体;上丘含有ChAT样纤维。上述胆碱能神经元,根据ChAT免疫反应可分为两种,一种胞体中等大小,免疫反应染色较深,突起显示较长;另一种胞体小,免疫反应染色浅,胞起显示短。以上观察说明各感觉传导系中的胆碱能纤维,一部分可能来自各自的胆碱能中间神经元,一部分可能来自其他部位。本研究尚未发现ACh直接参与各感觉传导的证据,因此ACh对各感觉传导路可能只起调节作用。     

Organization of brainstem noradrenaline hyperinnervation following neonatal 6-hydroxydopamine treatment in rat

Summary The organization and origin of NA axonal sprouting in individual brainstem nuclei was examined by fluorescence histochemistry and a radioenzymatic assay for noradrenaline (NA) in adult rats which were administered 6-hydroxydopamine (6-OHDA) as neonates. Significant 2–6 fold increases in NA content were measured in primary sensory nuclei, associational nuclei, somatic motor and visceral cranial nerve nuclei, reticular formation, raphe nuclei, and the inferior olivary complex. Fluorescence histochemical analysis reveals a major increase in the number of fluorescent fibers in most areas of the brainstem after 6-OHDA treatment. The normal pattern of innervation and axon morphology of each nucleus is retained after drug treatment. Bilateral locus coeruleus (LC) lesions in treated animals results in the denervation of only those nuclei which normally receive LC innervation (Levitt and Moore, 1979). The increased number of NA-containing axons in nuclei innervated by the lateral tegmental cell groups (LT) remains intact after LC ablation.The present results indicate that the brainstem NA sprouting following neonatal 6-OHDA administration occurs in a highly specified manner. The brainstem projections of both the LC and LT neuron groups exhibit marked axonal growth which is restricted to their specific brainstem terminal fields and probably occurs in response to the denervation of their respective, more rostral target areas.     

大鼠臂旁核内5-羟色胺阳性纤维和终末的来源

本研究采用荧光金(FG)逆行追踪与5-羟色胺(5-HT)免疫荧光组化染色相结合的双重技术观察了臂旁核(PBN)内5-HT阳性神经纤维和终末的来源。将FG注入PBN后,FG逆标神经元主要分布在三叉神经核簇、脑干网状结构外侧小细胞部、中缝核簇和中脑导水管周围灰质(PAG);免疫荧光组化染色的结果显示5-HT阳性神经元主要位于中缝核簇和PAG;在中缝核簇和PAG内可见FG逆标并呈5-HT阳性的双重标记神经元。上述结果表明,中缝核簇和PAG内的5-HT能神经元向PBN发出投射,它们在躯体和内脏感觉信息的传递和调控方面发挥重要作用。     

In Memoriam Rita Levi-Montalcini (1909–2012)

Abstract

The localization of acidic fibroblast growth factor (aFGF) in the male mouse brain was studied with biochemical and immunocytochemical techniques. Using two peptide-based aFGF antisera directed against independent epitopes, Western gel analysis of dissected brain demonstrated significant levels of aFGF immunoreactivity in the pons-medulla, hypothalamus and cerebellum. The cortex contained much less immunoreactivity. Consistent with the biochemical data, immunocytochemical analysis with the same two antisera demonstrated that aFGF immunoreactivity is localized in neuronal cell bodies in these regions. Numerous immunoreactive neurons were observed in the reticular formation of the pons and medulla, as well as in several other brainstem nuclei and areas. Immunoreactive neurons were also present in the lateral and medial hypothalamus, and some thalamic, subthalamic and epithalamic nuclei. In the basal ganglia, immunoreactive neurons were present in the amygdala and septum. Few intensely stained immunoreactive neurons were observed in the striatum, pallidum and neocortex. Limbic cortices contained more numerous immunoreactive neurons than neocortex. These results support the concept that aFGF is present in the brain, where it is heterogeneously distributed in neuronal cell bodies in regions involved in sensory, extrapyramidal motor, limbic and autonomic functions. The results are consistent with various neurotrophic, autogenic, and neuromodulatory functions associated with aFGF in the mammalian central nervous system.     

Anatomical distribution of somatostatin immunoreactivity in the infant brainstem

The distribution of somatostatin-immunoreactive structures in the infant brainstem was investigated using the peroxidase-antiperoxidase technique. A wide distribution of somatostatin-immunoreactive cell bodies and fibers was observed throughout the brainstem. Numerous somatostatin-immunoreactive cell bodies and fibers were present in several areas of the brainstem including the substantia grisea centralis and the reticular formation. Some immunoreactive cell bodies were seen in cranial nerve nuclei such as the nucleus praepositus, the nucleus nervi hypoglossi and the vestibular nuclei. Immunoreactive fibers were seen in the nucleus cuneatus, the locus coeruleus, the nucleus tractus solitarius, the nucleus ambiguus, the nucleus tractus spinalis nervi trigemini and the dorsal horn of the spinal cord. These data were in agreement with previous works on the human adult. However, a high density of somatostatin-immunoreactive cell bodies and fibers in the interpeduncular nucleus and in the nucleus centralis superior, and a dense network of somatostatin-immunoreactive fibers in the dorsal part of the nucleus inferior olivarius, were also observed. The role of somatostatin in some brainstem nuclei and its probable implication in some specific neuropathological diseases of the infant brainstem is discussed.     

Immunohistochemical Mapping of TRK-Fused Gene Products in the Rat Brainstem

The TRK-fused gene (TFG in human, Tfg in rat) was originally identified in human papillary thyroid cancer as a chimeric form of the NTRK1 gene. It was since reported that the gene product (TFG) plays a role in regulating phosphotyrosine-specific phosphatase-1 activity. As shown in the accompanying paper, we produced an antibody to rat TFG and used it to localize TFG to selected neurons in specific regions. In the present study, we mapped the TFG-positive neurons in the brainstem, cerebellum, and spinal cord of rats. In the brainstem, neurons intensely positive for TFG were distributed in the raphe nuclei, the gigantocellular reticular nucleus, the reticulotegmental nucleus of the pons, and some cranial nerve nuclei such as the trigeminal nuclei, the vestibulocochlear nuclei, and the dorsal motor nucleus of the vagus. Purkinje cells in the cerebellum and motor neurons in the spinal anterior horn were also positive for TFG. These results provide fundamental data for studying the functions of TFG in the brain.     

Glutaminase-like immunoreactivity in the lower brainstem and cerebellum of the adult rat

Distribution of putative glutamatergic neurons in the lower brainstem and cerebellum of the rat was examined immunocytochemically by using a monoclonal antibody against phosphate-activated glutaminase, which has been proposed to be a major synthetic enzyme of transmitter glutamate and so may serve as a marker for glutamatergic neurons in the central nervous system. Intensely-immunolabeled neuronal cell bodies were densely distributed in the main precerebellar nuclei sending mossy fibers to the cerebellum; in the pontine nuclei, pontine tegmental reticular nucleus of Bechterew, external cuneate nucleus, and lateral reticular nucleus of the medulla oblongata. Phosphate-activated glutaminase-immunoreactive granular deposits were densely seen in the brachium pontis and restiform body, suggesting the immunolabeling of mossy fibers of passage. In the cerebellum, neuropil within the granule cell layer of the cerebellar cortex displayed intense phosphate-activated glutaminase-immunoreactivity, and that within the deep cerebellar nuclei showed moderate immunoreactivity. These results indicate that many mossy fiber terminals originate from phosphate-activated glutaminase-containing neurons and utilize phosphate-activated glutaminase for the synthesis of transmitter glutamate. Intensely-immunostained neuronal cell bodies were further observed in other regions which have been reported to contain neurons sending mossy fibers to the cerebellum; in the dorsal part of the principal sensory trigeminal nucleus, dorsomedial part of the oral subnucleus of the spinal trigeminal nucleus, interpolar subnucleus of the spinal trigeminal nucleus, paratrigeminal nucleus, supragenual nucleus, regions dorsal to the abducens nucleus and genu of the facial nerve, superior and medial vestibular nuclei, cell groups f, x and y, hypoglossal prepositus nucleus, intercalated nucleus, nucleus of Roller, reticular regions intercalated between the motor trigeminal and principal sensory trigeminal nuclei, linear nucleus, and gigantocellular and paramedian reticular formation. Neuronal cell bodies with intense phosphate-activated glutaminase-immunoreactivity were also found in other brainstem regions, such as the paracochlear glial substance, posterior ventral cochlear nucleus, and cell group e. Although it is still controversial whether all glutamatergic neurons use phosphate-activated glutaminase in a transmitter-related process and whether phosphate-activated glutaminase is involved in other metabolism-related processes, the neurons showing intense phosphate-activated glutaminase-immunoreactivity in the present study were suggested to be putative glutamatergic neurons.     

An immunocytochemical mapping of methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the human brainstem

Using an indirect immunoperoxidase technique, we studied the distribution of immunoreactive fibers and cell bodies containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the adult human brainstem. Immunoreactive cell bodies were found in the reticular formation of the medulla oblongata (in which we observed the highest density of immunoreactive cell bodies) and the pons, the solitary nucleus, the hypoglossal nucleus, the medial and spinal vestibular nuclei, the lateral cuneate nucleus, the nucleus prepositus, the central gray of the pons and mesencephalon, the central and pericentral nuclei of the inferior colliculus, the superior colliculus, ventral to the superior olive and in the midline region of the pons and mesencephalon. The highest density of immunoreactive fibers containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) was found in the spinal trigeminal nucleus, the central gray and the reticular formation of the medulla oblongata, pons and mesencephalon, the solitary nucleus, the spinal vestibular nucleus, the dorsal accessory olivary nucleus, the raphe obscurus, the substantia nigra and in the interpeduncular nucleus. The widespread distribution of immunoreactive structures containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the human brainstem indicates that this neuropeptide might be involved in several physiological mechanisms, acting as a neurotransmitter and/or neuromodulator.     

大鼠孤束核内5－羟色胺能纤维的来源──HRP逆行追踪与5－羟色胺免疫组织化学双标记洁研究

用ＨＲＰ注入孤束核逆行追踪和５－羟色胺（５－ＨＴ）免疫组织化学相结合的双标记法，观察大鼠孤束核内的５－ＨＴ能纤维和终末的来源。结果在脑干内见到许多ＨＲＰ单标、５－ＨＴ单标和ＨＲＰ／５－ＨＴ双标细胞，其中ＨＲＰ／５－ＨＴ双标细胞主要分布于脑桥被盖核（２６．５７％）、脑桥网状核（２４．１９％）、中缝大核（２１．１７％），其次为中缝隐核（１２．７４％）、中缝苍白核（７．７８％），少数见于中缝背核、中脑导水管周围灰质和中缝脑桥核等处。而在结状神经节内仅见到ＨＲＰ单标细胞，未见到５－ＨＴ单标和ＨＲＰ／５－ＨＴ双标细胞。以上结果表明，大鼠孤束核的５－ＨＴ能纤维和终末主要来源于脑桥与延髓的５－ＨＴ神经元的投射。本研究提示脑桥与延髓内上述核团的５－ＨＴ神经元通过向孤束核的直接投射参与孤束核内脏功能的调控。     

Tachykinin immunoreactivity in terminals of trigeminal afferent fibers in adult and fetal monkey thalamus

Summary Immunocytochemistry of fetal and adult monkey thalamus reveals a dense concentration of tachykinin immunoreactive fibers and terminals in the dorsolateral part of the VPM nucleus in which the contralateral side of the head, face and mouth is represented. The immunoreactive fibers enter the VPM nucleus from the thalamic fasciculus and electron microscopy reveals that they form large terminals resembling those of lemniscal axons and terminating in VPM on dendrites of relay neurons and on presynaptic dendrites of interneurons. Double labeling strategies involving immunostaining for tachykinins after retrograde labeling of brainstem neurons projecting to the VPM failed to reveal the origin of the fibers. The brainstem trigeminal nuclei, however, are regarded as the most likely sources of the VPM-projecting, tachykinin positive fibers.Abbreviations AB ambiguus nucleus - AN abducens nucleus - C cuneate nucleus - CD dorsal cochlear nucleus - CL central lateral nucleus - CM centre médian nucleus - D dendrite - DR dorsal raphe - DV dorsal vagal nucleus - EC external cuneate nucleus - FM medial longitudinal fasciculus - FN facial nucleus - G gracile nucleus - Gc gigantocellular reticular formation - HN hypoglossal nucleus - ICP inferior cerebellar peduncle - IO inferior olivary complex - LC locus coeruleus - LL lateral lemniscus - LM medial lemniscus - M5 motor trigeminal nucleus - NS solitary nucleus - OS superior olivary complex - P dendritic protrusion - Pb parabrachial nucleus - Pc parvocellular reticular formation - PLa anterior pulvinar nucleus - Pp prepositus hypoglossi nucleus - Ps presynaptic region - Py pyramidal tract - P5 principal sensory trigeminal nucleus - R reticular nucleus - RF reticular formation - RL lateral reticular nucleus - S5 spinal trigeminal nucleus - T terminal - T5 spinal trigeminal tract - VL lateral vestibular nucleus - VM medial vestibular nucleus - VMb basal ventral medial nucleus - VPI ventral posterior inferior nucleus - VPL ventral posterior lateral nucleus - VPM ventral posterior medial nucleus - VR ventral raphe - VS superior vestibular nucleus - VSp spinal vestibular nucleus - ZI zona incerta - 5 trigeminal nerve - 6 abducens nerve - 7 facial nerve     

Somatostatin immunopositive neurons in the small intestine of the bullfrog (Rana catesbeiana).

Somatostatin immunopositive neurons in the small intestine of the bullfrog (Rana catesbeiana) were studied using immunohistochemistry and surgical denervation of the mesenteric nerve. Immunopositive nerve elements were distributed throughout the small intestine, including nerve fibers in the myenteric plexus, circular muscle layer, submucosal layer, and mucosa. Somatostatin immunopositive nerve cell bodies occurred in the myenteric plexus but not in the submucosal layer. These cell bodies were surrounded by immunopositive nerve fibers forming basket-like terminals, and thus some of these cells may be interneurons. After denervation of the mesenteric nerve, adrenaline immunopositive nerve fibers disappeared almost completely from the small intestine, but no changes occurred in the distribution of somatostatin immunopositive neurons. Neurons in the coeliac ganglion projecting into the small intestine were adrenaline immunopositive but somatostatin immunonegative. The results indicate that somatostatin immunopositive neurons in the small intestine of the bullfrog are primarily intrinsic in origin.     

Origin,distribution, and morphology of serotonergic afferents to the cat superior colliculus: a light and electron microscope immunocytochemistry study

Summary We have studied the serotonergic (5-HT) projection to the cat superior colliculus (SC) using serotonin antibody immunocytochemistry and retrograde transport of peroxidase-conjugated wheatgerm agglutinin (WGA-HRP). In 3 experiments, the two labels were combined in order to double label cells with both anti-5-HT and WGA-HRP. In the remaining experiments, the two labels were examined separately. Serotonin-like immunoreactive fibers were found throughout all layers of SC, but were most densely distributed within the zonal and upper superficial gray layers. Most 5-HT fibers were thin and had characteristic varicosities and terminal swellings. At the EM level, immunoreactive terminals and varicosities were found to contain small agranular vesicles and occasionally large granular vesicles (LGVs). Conventional synaptic densities were only rarely observed. Injections of WGA-HRP into SC resulted in labeling of neurons throughout the dorsal raphe nucleus and surrounding ventrolateral periaqueductal gray. Only a few cells were found in the raphe medianus and raphe pontis and none within the raphe magnus or other medullary raphe nuclei. Cells in the dorsal raphe giving rise to the SC projection varied in shape, size, and morphology and must represent more than one cell type. The morphology of these cells was indistinguishable from that of cells in the dorsal raphe which were double labeled by anti-5-HT and WGA-HRP. We conclude that the 5-HT innervation of the superior colliculus varies in density in different laminae, arises from several different cell types, and originates primarily from the dorsal raphe nucleus with minor projections from raphe medianus and raphe pontis.     

Immunohistochemical distribution of somatostatin-like immunoreactivity in the central nervous system of the adult rat

The localization and distribution of somatostatin (growth hormone release-inhibiting hormone; somatotropin release-inhibiting factor) have been studied with the indirect immunofluorescence technique of Coons and collaborators and the immunoperoxidase method of Sternberger and coworkers using specific and well-characterized antibodies to somatostatin, providing semiquantitative, detailed maps of somatostatin-immunoreactive cell profiles and fibers. Our results demonstrate a widespread occurrence of somatostatin-positive nerve cell bodies and fibers throughout the central nervous system of adult, normal or colchicine-treated, albino rats. The somatostatin cell bodies varied in size from below 10 micron up to 40 micron in diameter and could have only a few or multiple processes. Dense populations of cell somata were present in many major areas including neocortex, piriform cortex, hippocampus, amygdaloid complex, nucleus caudatus, nucleus accumbens, anterior periventricular hypothalamic area, ventromedial hypothalamic nucleus, nucleus arcuatus, medial to and within the lateral lemniscus, pontine reticular nuclei, nucleus cochlearis dorsalis and immediately dorsal to the nucleus tractus solitarii. Extensive networks of nerve fibers of varying densities were also found in most areas and nuclei of the central nervous system. Both varicose fibers as well as dot- or "dust-like" structures were seen. Areas with dense or very dense networks included nucleus accumbens, nucleus caudatus, nucleus amygdaloideus centralis, most parts of the hypothalamus, nucleus parabrachialis, nucleus tractus solitarii, nucleus ambiguus, nucleus tractus spinalis nervi trigemini and the dorsal horn of the spinal cord. One exception is the cerebellum which only contained few somatostatin-positive cell bodies and nerve fibers. It should be noted that somatostatin-positive cell bodies and fibers did not always conform to the boundaries of the classical neuroanatomical nuclei, but could often be found in areas between these well-established nuclei or occupying, in varying concentrations, only parts of such nuclei. It was difficult to identify with certainty somatostatin-immunoreactive axons in the animals studied. Some pathways could, however, be demonstrated, but further experimental studies are necessary to elucidate the exact projections of the somatostatin-immunoreactive neurons in the rat central nervous system.     

Substance P-immunoreactive and serotonin-containing neurones in the ventral brainstem of the cat

Substance P-like immunoreactive cell bodies have been described in the cat brainstem after local injections of colchicine. Substance P-containing neurons were found in the nucleus raphe pallidus, the nucleus raphe obscurus and at the caudal end of the nucleus raphe magnus. Two groups of substance P-positive (+) cells were also found in the ventrolateral medulla. Small substance P+ cells were present in a narrow band immediately ventral to the facial nucleus, and a second group of small and medium sized neurones was found in a strip ventrolateral to the rostral half of the inferior olive. Some of these cells lay in close proximity to the ventral surface of the brain. Double labelling studies indicated that within the raphe nuclei many substance P+ neurones also contained serotonin, while within ventrolateral areas of the medulla, the most rostral cell group stained only for substance P and the more caudal nucleus for both substance P and serotonin.     

Calcitonin gene-related peptide and somatostatin immunoreactivities in the rat lumbar spinal cord: sexually dimorphic aspects

The immunohistochemical distribution of calcitonin gene-related peptide and somatostatin in rat lumbar spinal laminae VII-X was investigated using the peroxidase-antiperoxidase technique. Within L1,2 laminae VII and X, calcitonin gene-related peptide and somatostatin fibers demarcate the location of preganglionic sympathetic neurons in a similar fashion in either sex but somatostatin is distributed in a sexually dimorphic manner in the lumbosacral (L5-S2) spinal cord with the male rat containing more somatostatin fibers and neurons than females. Within the ventral horn (lamina IX), calcitonin gene-related peptide has a sexually dimorphic distribution. Calcitonin gene-related peptide varicose fibers are found within the sexually dimorphic male cremaster nucleus but are virtually absent in the female cremaster nucleus. Calcitonin gene-related peptide varicose fibers are nearly absent in the remainder of the male and female lamina IX: this area includes the other two known sexually dimorphic spinal motonuclei: the dorsomedial and dorsolateral nuclei. Virtually all motoneurons in the lumbosacral spinal cord which are not sexually dimorphic contain calcitonin gene-related peptide. However, calcitonin gene-related peptide containing motoneurons have a heterogeneous distribution within sexually dimorphic nuclei. Calcitonin gene-related peptide containing motoneurons within the male and female cremaster nucleus are extremely rare. Some motoneurons within the male and female dorsomedial and dorsolateral nuclei contain calcitonin gene-related peptide with the female dorsomedial and dorsolateral nuclei containing a greater percentage of calcitonin gene-related peptide-containing motoneurons (c. 50%) than males (c. 20%). Somatostatin fibers are preferentially located in sexually dimorphic nuclei of either sex and are distributed in a sexually dimorphic manner within these nuclei with males containing a greater amount of somatostatin fibers than females. The amount of somatostatin immunoreactivity is most dense in the medial aspect of the dorsolateral nucleus, dense in the dorsomedial nucleus, moderate in the cremaster nucleus, and sparse in the lateral portion of the dorsolateral nucleus. In addition, a small column of motoneurons, between the dorsomedial and dorsolateral nuclei at the L5 level, is outlined by somatostatin fibers in females but is absent in males. Somatostatin containing motoneurons were not observed within the lumbar sexually dimorphic nuclei of either sex.     

Event-related potentials elicited by stimulus spatial discrepancy in humans

Female ddY mice were administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by gavage for 8 weeks prior to pregnancy. In the male breast-fed offspring born to the TCDD-exposed mice, serotonergic neurons in the brainstem were examined using an immunocytochemical method at 42 days of age. In all offspring, a marked decrease in the intensity of immunostaining occurred in all raphe nuclei compared with the control offspring. The number of serotonin-immunoreactive neurons in each raphe nucleus was measured by computer-assisted analysis. Approximately a quarter to half of immunoreactive neurons were detected in the TCDD-exposed offspring raphe nuclei compared with the control offspring. The present findings suggest that in utero and/or lactational TCDD exposure cause a long-lasting change in the serotonergic system in the raphe nuclei of offspring.