bluuebunny/crossref_metadata_2025 huggingface dataset:
Retrograde tracing of projections between the nucleus submedius, the ventrolateral orbital cortex, and the midbrain in the rat
Authors: Coffield J. A. , Bowen K. K. , Miletic V.
Published: January 2005

The fluorescent tracers fluoro‐gold and 1,1′‐dioctadecyl‐3,3,3,3‐tetramethyl indocarbocyanine perchlorate were used as retrograde markers to examine reciprocal connections between the rat nucleus submedius and the ventrolateral orbital cortex. In addition, midbrain projections to each of these regions were examined. In the prefrontal cortex, we found that input from the nucleus submedius terminates rostrally within the lateral and ventral areas of the ventrolateral orbital cortex. Conversely, the cortical input to the nucleus submedius originates from the medial and dorsal parts of the ventrolateral orbital cortex. Our data also demonstrated that neurons from the ventrolateral periaqueductal gray and the raphe nuclei project to the midline nuclei of the thalamus, including a small projection to the nucleus submedius. We further determined that regions within the ventrolateral periaqueductal gray and raphe nuclei project to the ventrolateral orbital cortex, and that these regions overlap with those that project to the nucleus submedius. These findings suggest that the nucleus submedius might be part of a neural circuit involved in the activation of endogenous analgesia. © 1992 Wiley‐Liss, Inc.
Effect of neonatal degranulation on the morphological development of rat CA3 pyramidal neurons: Inductive role of mossy fibers on the formation of thorny excrescences
Authors: Gaiarsa J. L. , Beaudoin M. , Ben‐Ari Y.
Published: January 2005

Intracellular peroxidase injections were made on CA3 pyramidal neurons from slices obtained from 3–60 day old control and experimental rats. Experimental rats had been irradiated at birth with γ‐rays to destroy the granule cells of the fascia dentata. Neonatal γ‐ray irradiation induced a clear cut reduction of the total number of granule cells (80% decrease at P60) and mossy fibers as revealed by Nissl and Timm stains. The number of branching points and segments, total dendritic length, and density of dendritic spines in the stratum radiatum and stratum oriens on CA3 pyramidal cells were not significantly different between control and irradiated rats. To quantify the development of thorny excrescences we measured the number and total area of the thorny excrescences per neuron at different stages of development. γ‐Ray irradiation induced a reduction in the number and total area of thorny excrescences. This effect was readily apparent by postnatal day (P) 12, and a reduction of 70% in the total area was observed at P30.

In conclusion, γ‐ray irradiation destroys the majority of granule cells and induces a reduction in the development of thorny excrescences. Our data strongly suggest that this effect is directly caused by the lack of mossy fibers rather than by the irradiation itself since other parameters (i.e., the number of segments and branching points, density of non‐mossy spines, and total dendritic length) were not affected. Therefore, we suggest that mossy fibers play an inductive role in the formation of thorny excrescences. © 1992 Wiley‐Liss, Inc.
Raphespinal and reticulospinal axon collaterals to the hypoglossal nucleus in the rat
Authors: Manaker Scott , Tischler Laura J. , Morrison Adrian R.
Published: January 2005

Neurons in the medial tegmental field project directly to spinal somatic motoneurons and to cranial motoneuron pools such as the hypoglossal nucleus. The axons of these neurons may be highly collateralized, projecting to multiple levels of the spinal cord and to many diverse regions at different levels of the neuraxis. We employed a double fluorescent retrograde tracer technique to examine whether medial tegmental neurons that project to the spinal cord also project to the hypoglossal nucleus. Injections of Diamidino Yellow into the hypoglossal nucleus and Fast Blue into the spinal cord produced large numbers of double labeled neurons in the medial tegmental field, particularly in the caudal raphe nuclei and adjacent ventromedial reticular formation. In these structures the number of neurons projecting to both the hypoglossal nucleus and the spinal cord was equivalent to the number of neurons projecting to multiple levels of the spinal cord observed in control animals. Fewer neurons projecting to both the hypoglossal nucleus and the spinal cord were observed in several other nuclei and subregions of the medial tegmental field, while almost no such neurons were observed in the lateral tegmental field or other pontomedullary structures. These results demonstrate that neurons of the caudal raphe nuclei and adjacent ventromedial reticular formation project to both the spinal cord and the hypoglossal nucleus, and support the concept that the diffuse projections to motoneuron pools from the medial tegmental field globally modulate both spinal and cranial somatic motoneuron excitability. © 1992 Wiley‐Liss, Inc.
Development of serotoninlike immunoreactivity in the embryonic nervous system of the snail Lymnaea stagnalis
Authors: Marois René , Croll Roger P.
Published: January 2005

In our initial effort to study the ontogeny of the gastropod nervous system, we used histological techniques to examine the post‐embryonic development of cells which exhibit serotoninlike immunoreactivity in Lymnaea (Croll and Chiasson, J. Comp. Neurol. 230:122–142, '89). The present study complements that report by examining the embryonic development of these neurons. The first serotoninlike immunoreactive (SLIR) cells to be detected in the embryos are the paired C4 neurons of the cerebral ganglia. These cells are faintly visible at about 37–38% of embryonic development and have already produced axons which traverse the cerebral commissure. By about 2–3% later the axon tips reach the pedal ganglia and appose the next SLIR cells to appear, the EPe1 neurons. Over the next 30% of development four more pairs of cerebral neurons are added adjacent to the C4 neurons and over ten cells are added to each of the pedal ganglia. At about 70% of development SLIR fibers are first detected in the parietal and visceral ganglia forming the abdominal ring. Around this time the somata of the Cl neurons also first appear in the cerebral ganglia together with their prominent axons projecting to the buccal ganglia. The last 30% of development is marked by a massive addition of SLIR cells (up to 60) in each pedal ganglion. The early appearance of the first SLIR cells suggests that they may be among the first nerve cells to differentiate and that they may play central roles in the formation of the CNS. We hypothesize that most of the animal's neural circuitry is laid down during embryogenesis by a stereotypic ontogenetic program with post‐embryonic neurogenesis subserving mostly compensatory and modulatory purposes. © 1992 Wiley‐Liss, Inc.
Alpha‐melanocyte‐stimulating hormone (α‐MSH) in the brain of the African lungfish, Protopterus annectens: Immunohistochemical localization and biochemical characterization
Authors: Vallarino Mauro , Bunel Denis Tranchand , Vaudry Hubert
Published: January 2005

The distribution of alpha‐melanocyte‐stimulating hormone (α‐MSH) containing neurons and the molecular forms of α‐MSH‐related peptides exhibit substantial differences in the brains of fish and amphibians. Lungfishes, which share similarities with both fishes and tetrapods, represent a valuable group in which to investigate the neuroanatomical and neurochemical facets of evolution. In the present study, we have localized and characterized α‐MSH‐immunoreactive peptides in the central nervous system of the African lungfish Protopterus annectens. Perikarya exhibiting α‐MSH‐like immunoreactivity were observed in two distinct regions of the hypothalamus: the rostral part of the preoptic nucleus and the caudal part of the hypothalamus. In the caudal hypothalamus most α‐MSH‐immunopositive perikarya were located in both the subependymal and deepest layers of the ventral periventricular region. Scattered α‐MSH‐immunopositive cells were occasionally detected in the dorsal side of the caudal hypothalamus. The α‐MSH‐immunoreactive material localized in the brain was characterized by combining high‐performance liquid chromatography (HPLC) analysis and radioimmunological detection. The displacement curves obtained with synthetic α‐MSH and serial dilutions of brain and pituitary extracts were parallel. HPLC analysis of lungfish hypothalamic extracts showed that the major immunoreactive peak coeluted with synthetic desacetyl α‐MSH and its sulfoxide derivative. An additional peak coeluted with synthetic sulfoxide α‐MSH. In contrast, in the pituitary, the predominant form of α‐MSH‐like material coeluted with the N,O‐diacetyl α‐MSH standard. These results provide the first evidence for the presence of α‐MSH‐related peptides in the brain of a lungfish. The distribution of α‐MSH neuronal systems in the lungfish is very similar to that reported in amphibians, supporting the existence of phylogenetic convergences between these two vertebrate groups. © 1992 Wiley‐Liss, Inc.
Morphology of single vestibulospinal collaterals in the upper cervical spinal cord of the cat: I. Collaterals originating from axons in the ventromedial funiculus contralateral to their cells of origin
Authors: Donevan A. H. , Fleming F. L. , Rose P. K.
Published: January 2005

Vestibulospinal neurons in the medial and descending vestibular nuclei have widespread bilateral terminations in the upper cervical spinal cord. These terminations arise from axons travelling in several funiculi, including the ventromedial, ventrolateral, lateral, and dorsolateral funiculi in addition to the dorsal columns. The purpose of the present study was to examine the morphology of single Vestibulospinal collaterals which terminate in the upper cervical spinal cord and which originate from axons located in one of these funicular pathways, the ventromedial funiculus, contralateral (cVMF) to their cells of origin in the vestibular nuclei. The 32 collaterals described were selected from two separate sets of experiments which took advantage of different techniques. Nineteen of the collaterals were labelled following Phaseolus vulgaris leucoagglutinin (PHA‐L) injections into the medial vestibular nucleus and medial regions of the descending vestibular nucleus. The remaining 13 collaterals originated from physiologically identified Vestibulospinal axons that were stained after intra‐axonal injections of horseradish peroxidase (HRP). The combined projection of all cVMF axon collaterals spread from laminae V to IX, and included the central cervical nucleus. There was a high degree of variability in the pattern of terminations of individual collaterals. This variability was more pronounced among PHA‐L‐labelled collaterals than HRP‐labelled collaterals whose terminations were restricted to laminae VIII and IX. Some PHA‐L‐labelled collaterals had terminations which were focused within a single lamina, whereas others had termination zones spanning as many as four laminae. The differences between collaterals were compounded when the characteristics of branching patterns were considered. Some collaterals which occupied similar termination zones had different branching structures. Generally, collaterals which shared the same parent axon had similar, although not always identical, terminations and branching patterns.

The unexpected heterogeneity of these Vestibulospinal collaterals suggests that Vestibulospinal cells, even those whose axons travel in the same funiculus, may serve different functions. © 1992 Wiley‐Liss, Inc.
Distribution of GABAergic interneurons immunoreactive for calretinin, calbindin D28K, and parvalbumin in the cerebral cortex of the lizard Podarcis hispanica
Authors: Martínez‐Guijarro F. J. , Freund T. F.
Published: January 2005

The types and distribution of cells containing three calcium‐binding proteins, calretinin, calbindin D28K and parvalbumin, have been studied by immunocytochemistry in different areas of the cerebral cortex of lizards. Cross‐reactivity of the antisera has been excluded by demonstrating the existence of several cell groups immunoreactive for one but not the other two calcium‐binding proteins.

In the dorsal and dorsomedial cortices all three proteins coexist in a single subpopulation of γ‐aminobutyric acid (GABA)ergic neurons, the terminals of which form pericellular baskets around cell bodies of bipyramidal neurons. The somata of these neurons are largely restricted to the cellular and inner plexiform layers, but the dendrites usually penetrate all layers, allowing the neurons to sample input from all possible sources. A small number of parvalbumin‐containing neurons in the outer plexiform layer do not contain the other two proteins. The medial cortex, which is likely to be homologous to the mammalian dentate gyrus, only contains parvalbumin‐immunoreactive neurons. The dendritic trees of these cells appear to avoid the Timm‐positive fields receiving input from zinc‐rich fiber collaterals, originating from principal cells. The lateral cortex contains calbindin D28K‐immunoreactive GABAergic neurons, which lack the other two calcium‐binding proteins. These neurons have horizontally running dendrites in the outer plexiform layer, but their axon terminals could not be visualized.

The present study uncovered important similarities and differences between the lizard and the mammalian archicortex in the types of neurons containing calcium‐binding proteins. As in mammals, different cell types evolved in the lizard to inhibit the perisomatic versus the distal dendritic region of principal cells, the calcium‐binding protein‐containing neurons being responsible for the former, and neuropeptide‐containing neurons for the latter. The results also suggest that further neurochemical diversion of GABAergic interneurons coupled to a functional specialization took place during phylogenetic development from reptiles to mammals. © 1992 Wiley‐Liss, Inc.
Organization of the septal organ projection to the main olfactory bulb in adult and newborn rats
Authors: Giannetti N. , Saucier D. , Astic L.
Published: January 2005

The septal organ, which is regarded as an olfactory subsystem, is a small patch of sensory epithelium located ventral to the main olfactory sheet on the septal wall of the nasal cavity. The only consensus to date regarding some proper area of projection of this subsystem is that the septal organ projects to the medial aspect of the main olfactory bulb. The purpose of our study was to analyze precisely the topographical organization of the bulbar projection of the septal organ in adult rats and in 3‐ to 15‐day‐old rats following WGA‐HRP placements at the level of the septal epithelium. Results show that the septal organ projects exclusively to the posterior half of the main olfactory bulb and its projection area is mainly restricted to the ventromedial bulbar aspect. When the septal organ was fully injected, the pattern of bulbar projection was characterized by two types of glomerular labeling: (1) presence of single heavily labeled glomeruli identified as “septal” glomeruli, since they were mainly built up by afferents coming from the septal organ and (2) presence of a thin network of labeled septal fibers distributed in glomeruli which were mainly formed by afferents coming from the main olfactory epithelium. Although the pattern of mucosobulbar projection of the septal organ is already established in newborns, a significant increase in the number of “septal” glomeruli occurs during the first 15 postnatal days. Anatomical data indicate that even if the projection of the septal organ does not appear completely segregated in the olfactory bulb, this projection is not either exactly similar to that of the main olfactory epithelium. © 1992 Wiley‐Liss, Inc.
Developmental differentiation of MAP2 expression in the central versus the peripheral and efferent projections of the inner ear
Authors: Hafidi A. , Fellous A. , Ferhat L. , Romand M.‐R. , Romand R.
Published: January 2005

The goal of this study was to extend our knowledge of MAP2 localization in the peripheral nervous system of mammals, since most results on MAP2 distribution are obtained in the central nervous system (CNS). This study shows the presence of microtubule‐associated protein 2b (MAP2b) and MAP2c in the inner ear and describes the immunocytochemical distribution of MAP in adult and developing spiral ganglion of the rat by using a well‐characterized antibody for MAP2a and MAP2b. (This antibody does not recognize the immature MAP2c). MAP2 labeling is already present in spiral ganglion neurons at 16 days of gestation. From this stage and up to the first postnatal week, MAP2 labeling was strong in all spiral ganglion neurons and their central processes.

Double immunostaining at the 16‐day stage with anti‐MAP2 and anti‐neurofilament (NF) antibodies mainly showed NF labeling in central branches that corresponded to anatomically and functionally described axons of spiral neurons. The peripheral branches lacked MAP2 labeling. In neonatal and postnatal stages, MAP2 reactivity was located in spiral ganglion perikarya and their neurites. The intensity of adult labeling was, however, lower than in younger animals.

The antibody used in this study did not label axons originating in the CNS as seen by a negative response in efferent fibers from the intraganglionic spiral bundle of the cochlea.

Our results suggest that during ontogenesis, MAP2 is highly expressed in the central projection of spiral ganglion neurons, and then is reduced to lower quantities in the central branch after the first postnatal week and persists into adulthood. Concurrently, a weak reaction develops in the peripheral projection and remains throughout the adult. Since MAP2 expression is associated with central projection outgrowth (axons) of the early developing spiral ganglion and not the peripheral, this is a distinguishing feature for central versus peripheral projection as structurally and functionally different entities. © 1992 Wiley‐Liss, Inc.
Morphology of intracellularly labeled interneurons in the dentate gyrus of the immature rat
Authors: Seay‐Lowe Starie L. , Claiborne Brenda J.
Published: January 2005

Although many aspects of the morphological development of interneurons in the dentate gyrus have been described, the full extent of their dendrites and local axon projections in immature rodents has not been examined. Here intracellular labeling was used to assess the branching patterns of interneurons in the dentate gyrus of rat pups between 7 and 9 days of age. Labeled neurons were located within or just below the granule cell layer, and most were classified as GABAergic basket neurons on the basis of their dendritic morphologies.

All labeled interneurons exhibited immature characteristics. Spines were present on cell bodies and dendrites, and growth cones were visible on some dendrites and axons. In spite of these immature features, the dendrites and axon arbors of the labeled neurons were extensive. Many apical dendrites reached the top of the molecular layer, and a number of basal dendrites extended to the CA3 pyramidal cell layer of the hippocampus. Elaborate axon plexuses were present within the dentate gyrus itself, and axon collaterals of several neurons extended beyond the dentate gyrus to branch within regions CA3 and CA1 of the hippocampus.

These results indicate that the dendrites and axon collaterals of dentate interneurons are extensive at a time when the principal neurons, the granule cells, are still proliferating. These data are consistent with the idea that GABAergic interneurons may influence granule cell development in the dentate gyrus, as well as pyramidal cell maturation in the hippocampus proper.
Musculotopic organization of the hypoglossal nucleus in the cynomolgus monkey, Macaca fascicularis
Authors: Sokoloff Alan J. , Deacon Terrence W.
Published: January 2005

The movements of the tongue in feeding and vocalization are enabled by a complex system of interdigitated muscle fibers in the tongue body. Because of this complexity, the detailed anatomical connections between individual intrinsic tongue muscles and corresponding motoneurons in the hypoglossal nucleus have not been described for any mammal. In this study we describe the distribution of retrogradely labeled neurons in the hypoglossal nucleus, following injections of wheat‐germ agglutinin‐horseradish peroxidase into different regions of the tongue of 21 cynomolgus monkeys. These experiments demonstrate a spatial organization of hypoglossal motoneurons that reflects the anatomical and functional organization of tongue body muscles: motoneurons innervating the transversus and verticalis muscles are located in medial hypoglossal nucleus regions, motoneurons innervating the genioglossus are located in intermediate hypoglossal nucleus regions, motoneurons innervating the hyoglossus and inferior longitudinalis are located in ventrolateral hypoglossal nucleus regions, and motoneurons innervating the styloglossus and superior longitudinalis are located in dorsolateral hypoglossal nucleus regions. Motoneurons innervating the suprahyoid muscle, the geniohyoid, are situated in a cell column separated ventrally from the main body of the hypoglossal nucleus. Motoneurons innervating the palatoglossus are located in the nucleus ambiguus and, possibly, in dorsolateral hypoglossal nucleus regions. Motoneurons of the medial divisions of the hypoglossal nucleus innervate tongue muscles that are oriented in planes transverse to the long axis of the tongue whereas motoneurons of the lateral divisions innervate tongue muscles that are oriented parallel to this axis. These results suggest that the segregation of motoneurons corresponds to the functional distinction between tongue protrusion and retrusion.
Embryonic development of synapses on spiking local interneurones in locust
Authors: Leitch Beulah , Laurent Gilles , Shepherd David
Published: January 2005

The development of synapses on an identified population of spiking local interneurones in the thoracic ganglia of embryonic locusts was examined by means of intracellular horseradish peroxidase injection and electron microscopy. In adult locusts, spiking local interneurones of the midline group receive direct inputs onto a ventral field of branches from leg mechanosensory afferents and in turn make output synapses, mainly from a dorsal field of branches, directly upon leg motor neurones, nonspiking local interneurones, and intersegmental interneurones. The aim of this study is to examine the development of these connections. These interneurones are born relatively late in embryogenesis and are not identifiable until approximately 55% of development. At this time (55–60%) only simple filopodial contacts or punctate contacts are evident between the stained interneurones and other neurones. By 65–70% embryogenesis, vesicles are found adjacent to regions where apposed membranes are symmetrically thickened with amorphous electron‐dense material. These symmetrical contacts lack distinct presynaptic bar‐shaped densities and therefore, are not considered to be synapses. At this stage, the interneurones do not produce action potentials upon intracellular injection of depolarising current. Morphologically identifiable synapses, with vesicles, a presynaptic bar, and relatively little postsynaptic density, are first evident at 70–75%, coincident with the time of arrival of the majority of leg mechanosensory afferents into the central nervous system. At this stage, action potentials and synaptic potentials are also recorded for the first time. The midline spiking interneurones thus become electrically excitable when synapses are first recognisable, at approximately 70% embryogenesis. Most of the synapses found on the interneurones are outputs. The ratio of outputs to inputs on ventral branches is 7.5:1 which contrasts markedly to the adult ratio of 1:2. By 85–90%, output synapses still predominate on the ventral branches, but the ratio of outputs to inputs is reduced to almost 2:1. Dorsal branches have predominantly output synapses throughout embryogenesis. The ratio of dorsal outputs to inputs at 85–90% is 8.5:1 which compares with the adult ratio of 6.5:1 At this stage, action potentials and synaptic activity are always recorded.© 1992 Wiley‐Liss, Inc.
Butyrylcholinesterase‐rich neurons in rat brain demonstrated by a sensitive histochemical method
Authors: Tago Hisao , Maeda Toshihiro , McGeer Patrick L. , Kimura Hiroshi
Published: January 2005

Butyrylcholinesterase (BChE) is a highly active enzyme in brain, but little is known about its physiological functions. One obstacle has been the lack of a sensitive and specific method for determining its cellular localization. We report here on a histochemical technique that has permitted BChE to be detected in neuronal, glial, and vascular structures. The method, which utilizes butyrylthiocholine iodide as the substrate, is a modification of our previously described method for acetylcholinesterase (AChE) histochemistry. BChE‐rich neuronal somata stained much more intensely than capillaries or glia. Prominent neuronal groups were located in the anterodorsal, laterodorsal, anteroventral, reuniens, centrolateral, paratenial, and periventricular thalamic nuclei, the laterodorsal tegmental nucleus, the pedunculopontine tegmental nucleus, and the dorsal motor nucleus of vagus. Several other areas of the forebrain and brainstem showed modest numbers of positive cells. No positive cells were detected in the striatum, hippocampus, and most parts of the hypothalamus, which are regions containing numerous AChE‐rich neurons. Although the distribution pattern of BChE‐rich neurons differed from that of AChE‐rich neurons, some neuronal groups contained both esterases. The results suggest that BChE may play a unique role in neuronal function, particularly since many BChE‐rich neurons have not been identified as to neurotransmitter type. © 1992 Wiley‐Liss, Inc.
Cholecystokinin concentrations and peptide immunoreactivity in the intact and deafferented medullary dorsal horn of the rat
Authors: Jacquin Mark F. , Beinfeld Margery C. , Chiaia Nicolas L. , Zahm Daniel S.
Published: January 2005

To further address the hypothesis that cholecystokinin (CCK) in the medullary dorsal horn (MDH) arises from intrinsic or higher‐order neurons. CCK‐8‐specific radioimmunoassay (RIA) and immunohistochemichal (IHC) experiments were carried out in adult rats after trigeminal tractotomy. RIA of punches from deafferented superficial layers of the MDH revealed no significant change in CCK levels vs. the control right side. In this same area, IHC revealed modest reductions in CCK, gastrin, and substance P staining. Calcitonin gene‐related peptide (CGRP) staining was reduced substantially. Gastrin immunoreactive cell bodies, present normally in inner lamina II, were reduced in number.

RIA and IHC methods were also used to assess MDH CCK concentrations in adult rats subjected to left infraorbital nerve section at birth. The left medulla contained significantly higher levels of CCK than the control right medulla (1.27 ± 0.19 vs. 0.97 ± 0.11 ng/mg protein). IHC revealed a dense band of CCK‐like staining in laminae I and II ipsi‐ and contralateral to the lesion. Thus, neonatal deafferentation elevates medullary CCK.

To determine if the neonatal lesion‐induced increase in medullary CCK is due to primary afferent or higher‐order reorganization, RIA and IHC experiments were run after infraorbital nerve section at birth and trigeminal tractotomy in adulthood. RIA revealed no significant change in CCK levels caudal to the tractotomy, although they were higher than control levels in 9 of 12 cases. IHC revealed modest reductions in CCK, substance P, and gastrin staining that resembled the reductions observed in tractotomy‐alone cases.

These data suggest that (1) most MDH CCK is of non‐primary afferent origin, (2) gastrin immunoreactivity in layer II probably originates in CCK‐containing cells intrinsic to layer II, the expression of which is dependent upon trigeminal primary afferent input, (3) neonatal V deafferentation induces increased CCK in the superficial MDH, oflecting reorganized intrinsic or higher‐order inputs, and (4) higher‐order substance P in the MDH is robust. © 1992 Wiley‐Liss, Inc.
Galanin receptors in the brain of a teleost: Autoradiographic distribution of binding sites in the Atlantic Salmon
Authors: Holmqvist Bo I. , Carlberg Mats
Published: January 2005

The distribution of galanin (GAL) binding sites in the brain of the Atlantic salmon (Salmosalar) was investigated by means of radioligand binding in conjunction with autoradiography by using high‐performance liquid chromatography (HPLC) characterized radio‐iodinated porcine galanin ([125I]GAL). On slide‐mounted sections of frozen salmon brain homogenate, [125I]GAL(4 nM) bound rapidly and reversibly to a single population of sites with a Kd of 1.0 ± 0.08 nM (n = 3) and Bmax of 2.380 ± 0.19 fmol/mg wet tissue. Specific [125I]GAL binding was found in cellular regions, in fiber tracts, and in neuropil areas throughout the brain, except for in the olfactory bulb, pineal organ, and cerebellum.

Autoradiographic microdensitometric measurements revealed high total [125I]GAL binding in the ventral hypothalamus (inferior lobes; around 7–12 fmol/mg tissue), the dorsal spinal cord (between 6 and 12 fmol/mg tissue), sublayers of the optic tectum (around 8 fmol/mg), torus semicircularis (around 7 fmol/mg), and glomerular complex (around 6 fmol/mg). Intermediate densities of [125I]GAL binding (3–5 fmol/mg tissue) were found in the pituitary, telencephalon, dorsolateral thalamic nucleus, and raphe nuclei and in association with the forebrain bundles. Except for in the optic tectum, there is a good concordance of [125I]GAL binding sites and GAL‐immunoreactive fiber projections in most brain areas of the salmon. The wide distribution of GAL binding sites provides further evidence that a GAL‐like substance might be involved in a diversity of brain functions of teleosts. The topographic distribution of target sites in the hypothalamo‐hypophyseal axis indicates that GAL‐like substances may have both direct and indirect effect on pituitary functions while in extrahypothalamic areas, functional implications by GAL may include involvement in somatosensory, central gustatory, olfactory, and visual functions.

This study provides evidence for the presence of a specific GAL receptor in the brain of the Atlantic salmon. Together the distribution of GAL binding and GAL‐like molecules provide a covering delineation of the GAL neuronal system in the brain of the Atlantic salmon. Comparisons with mammals suggest that the GAL receptor molecule has been well preserved during evolution and that GAL‐like substances may be present, and even possess similar functional properties, throughout the vertebrate phylogeny. © 1992 Wiley‐Liss, Inc.
Comparative molecular neuroanatomy of cloned GABAAreceptor subunits in the rat CNS
Authors: Persohn E. , Malherbe P. , Richards J. G.
Published: January 2005

γ‐Aminobutyric acidA(GABAA) receptors in the mammalian central nervous system (CNS) are members of a family of ligand‐gated ion channels consisting of heterooligomeric glycoprotein complexes in synaptic and extrasynaptic membranes. Although molecular cloning studies have identified 5 subunits (with ∼40% amino acid homology) and isoforms thereof (∼70% homology), namely α1–6, β1–4, γ1–3, δ, and ρ, the subunit composition and stoichiometry of native receptors are not known.

The regional distribution and cellular expression of GABAAreceptor messenger RNAs (mRNAs) in the rat CNS have now been investigated by in situ hybridization histochemistry with subunit‐specific35S‐labelled oligonucleotide probes on adjacent cryostat sections. Whereas α1, β2, and γ2 transcripts were the most abundant and ubiquitous in the rat brain—correlating with the radioautographic distribution of GABAAreceptors revealed by an ionophore ligand—others had a more restricted expression while often being abundant. For example, α2 transcripts were found only in the olfactory bulb, cerebral cortex, caudate putamen, hippocampal formation, and certain lower brain stem nuclei; α3 only in the olfactory bulb and cerebral cortex; α5 in the hippocampal formation; and α6 only in cerebellar granule cells. In addition, β1, β3, γ1, and δ mRNAs were also uniquely expressed in restricted brain regions. Moreover, in the spinal cord, α1–3, β2,3, and γ2 mRNAs were differently expressed in Rexed layers 2–9, with α2, β3, and γ2 transcripts most prominent in motoneurons of layer 9.

Although differential protein trafficking could lead to the incorporation of some subunits into somatic membranes and others into dendritic membranes, some tentative conclusions as to the probable composition of native proteins in various regions of the CNS may be drawn. For example, according to the strength of the hybridization signal the following subunits might be expected to play a prominent role in GABAergic neurotransmission in the corresponding regions: α1, β2 (1,3), γ2 in olfactory bulb mitral cells; α2, β3, γ2, δ in caudate putamen; α1,3 (2,5), β2,3, γ2 in cerebral cortex; α1, β2, γ1,2 in pallidum; α1,2,5, β1–3, γ2 in hippocampus; α1,5, β3, γ2, δ in dentate gyrus; α1, β2, γ1,2 in substantia nigra zona reticularis; α1, β2, γ2 in cerebellar Purkinje cells; α1,6, β2,3, γ2, δ in granule cells; α1,2, β2,3, γ2 in vestibular and facial nuclei; and finally α2, β3, γ2 in motoneurons of Rexed layer 9 in the spinal cord. © 1992 Wiley‐Liss, Inc.
Nerve growth factor‐induced sprouting of mature, uninjured sympathetic axons
Authors: Isaacson L. G. , Saffran B. N. , Crutcher K. A.
Published: January 2005

The infusion of nerve growth factor (NGF) into the lateral ventricle ofthe mature rat brain elicits a sprouting response from axons associated with the intradural segment of the internal carotid artery. Using electron microscopic techniques, we observed a three–fold increase in the total number of perivascular axons. This NGF‐elicited response is characterized by a dramatic reduction in glial cell ensheathment similar to that observed during development and by the presence of profiles devoid of organelles that may represent newly formed sprouts. In spite of the increase in axon number, no significant changes in the percentage of small, medium, or large axons wereobserved.

The three‐fold increase in the total number of axons was accompanied byan increase in the number of axons/fascicle but no change in the number of fascicles. This, along with the observation that a majority of sprouted axons were associated with other axons, supports the idea that the sprouted axons tend to associate preferentially with other axons. Bilateral superior cervical ganglionectomies following cytochrome C infusion indicate that approximately 60% of the axons associated with the internal carotid artery arise from the superior cervical ganglion and that the majority of axons contacting the smooth muscle layer arise from this ganglion. Sympathectomy following NGF infusion resulted in a 79% reduction in the total number of perivascular axons, demonstrating overwhelmingly that the majority of sprouted axons are sympathetic fibers. These results demonstrate that infusion of NGF into the mature rat brain results in the preferential sprouting of sympathetic axons associated with the internal carotid artery. These findings are consistent with the hypothesis that NGF normally plays a role in the regulation of autonomic cerebrovascular innervation in the adult animal and that mature, uninjured sympathetic neurons remain responsive to NGF. © 1992 Wiley‐Liss, Inc.
A quantitative dendritic analysis of wernicke's area in humans. I. Lifespan changes
Authors: Jacobs Bob , Scheibel Arnold B.
Published: January 2005

Age‐related increases and decreases have been described in cortical dendritic neuropil. Here, we examine age‐related changes in the basilar dendrites of supragranular pyramidal cells in human superior temporal gyrus (i.e., Wernicke's area) of left and right hemispheres. Tissue was obtained from 20 neurologically normal right‐handers from 18–79 years: 10 males (Mage = 52.2 years; SD age = 17.4) and 10 females (Mage = 47.8; SDage = 20.5). In tissue prepared by a modified rapid Golgi technique, ten pyramidal cells were sampled from each hemisphere and evaluated according to the following parameters: total dendritic length, mean dendritic length, and dendritic segment count.

Despite considerable interindividual variation, the data exhibited significant dendritic degeneration with aging. There was an age‐related decrease in total dendritic length (r[20] = −0.44; P < 0.05) and especially in mean dendritic length (r[20] = –0.69; P < 0.001) with increasing age. Age‐mean dendritic length correlations were negative for all segment orders and revealed a progressive decrease in segment length in more distal branches. The number of dendritic segments remained relatively stable across the age span sampled. The data also indicated that interhemispheric dendritic asymmetries decreased with age. Individuals under 50 years of age had significantly greater total dendritic length values in the left hemisphere. Interhemispheric dendritic differences were not significant in individuals over 50. © 1993 Wiley‐Liss, Inc.
Specificity in the efferent projections of the nucleus accumbens in the rat: Comparison of the rostral pole projection patterns with those of the core and shell
Authors: Zahm D. S. , Heimer Lennart
Published: January 2005

The efferent connections of the rostral pole of the rat accumbens, where distinct core and shell subterritories can not be identified, were examined with the aid of the anterogradely transported plant lectin, Phaseolus vulgaris‐leucoagglutinin (PHA‐L), for comparison with the previously reported projection patterns of the accumbal core and shell. Injection sites and transported PHA‐L were evaluated with the aid of reference to adjacent sections processed to display substance P or calbindin 28 kD immunoreactivities, i.e., markers that demonstrate the core and shell. Lateral parts of the rostral pole gave rise to a “core‐like” projection system that involved the rostroventral globus pallidus, subcommissural ventral pallidum, entopeduncular nucleus and an adjacent part of the lateral hypothalamus, lateral ventral tegmental area, dorsal pars compacta, and structures in the lateral mesencephalic tegmentum and central grey. The medial part of the rostral pole gave rise to a “shell‐like” innervation of the subcommissural ventral pallidum, lateral preoptic region, lateral hypothalamus, ventral tegmental area, dorsalmost pars compacta, retrorubral field, lateral midbrain tegmentum, and central grey. In contrast to the large numbers of axon varicosities observed through the entire length of lateral hypothalamus following shell injections, dense accumulations of axon collaterals and varicosities in hypothalamus were limited to the levels of origin of the stria medullaris bundle and entopeduncular nucleus and to the posterlateral region following medial injections. The medial part of the rostral pole contributed some projections to preoptic and sublenticular regions, but not to the bed nucleus of the stria terminalis. Noteworthy concentrations of calbindin immunoreactive cells observed in the lateral rostral pole correlate with the origin of the “basal ganglia‐like” projection system, provoking the speculation that ventral striatal calbindin immunoreactive cells contribute principally to basal ganglia‐like projections while cells lacking calbindin immunoreactivity contribute to the innervation of hypothalamus and midbrain tegmentum. © 1993 Wiley‐Liss, Inc.
Detection of the 5‐HT1Areceptor and 5‐HT1Areceptor mRNA in the rat bowel and pancreas: Comparison with 5‐HT1Preceptors
Authors: Kirchgessner A. L. , Liu M.‐T. , Howard M. J. , Gershon M. D.
Published: January 2005

We tested the hypothesis that the rat bowel and pancreas contain 5‐HT1Areceptors.3H‐8‐hydroxy‐2‐(di‐n‐propylamino) tetralin (3H‐8‐OH‐DPAT) was used as a radioligand. Binding of3H‐8‐OH‐DPAT to membranes derived from the myenteric plexus and the pancreas was investigated by rapid filtration. Alternatively, radioautography was employed to locate3H‐8‐OH‐DPAT binding sites in frozen sections of unfixed bowel or pancreas. An excess of 5‐HT (10 μM) was used to define nonspecific binding. Saturable, high affinity binding of3H‐8‐OH‐DPAT to enteric (Kd= 2.8 ± 1.1 nM; Bmax=83.8 ± 4.3 fmol/mgproteim) and pancreatic (Kd= 6.6 ± 1.3 nM; Bmax= 44 ± 2.2 fmol/mg protein) membranes was found. The binding of3H‐8‐OH‐DPAT to enteric and pancreatic membranes was inhibited by 8‐OH‐DPAT, NAN‐190, and spiperone. In contrast, the binding of3H‐8‐OH‐DPAT to enteric and pancreatic membranes was not inhibited by 5‐carboxyamidotryptamine, or by avariety of compounds known to bind to other subtypes of 5‐HT receptor. Digoxigenin‐labeled oligonucleotides were found to detect mRNA encoding the 5‐HT1Areceptor in a subset of neurons in myenteric and submucosal ganglia. In contrast, 5‐HT1AmRNA was not found in the pancreas. Radioautography revealed that the highest density of3H‐8‐OH‐DPAT binding sites was found in the stomach. These sites were especially numerous in the lamina propria adjacent to gastric glands, and in myenteric ganglia. Pancreatic 5‐HT1Areceptors were located on nerves, lymphoid tissue (especially the capsule of nodes), and on cells scattered in the pancreatic parenchyma. The concentration of3H‐8‐OH‐DPAT binding sites in the rat bowel and pancreas was less than that of3H‐5‐HT binding sites; however, the distribution of3H‐8‐OH‐DPAT binding sites was similar to that of sites that bind3H‐5‐HT. It is concluded that the rat gut and its extension in the pancreas contains 5‐HT1Areceptors. Many, if not all, of the nerve cells and processes that express 5‐HT1Areceptors express 5‐HT1preceptors as well. The function of these receptors in the physiology of the entero‐pancreatic innervation remains to be determined. © 1993 Wiley‐Liss, Inc.
Retinal transplants in congenitally blind mice: Patterns of projection and synaptic connectivity
Authors: Horsburgh Gwynn M. , Lund Raymond D. , Hankin Mark H.
Published: January 2005

Embryonic retinae were transplanted onto the midbrain of neonatal congenitally anophthalmic mice and neonatal mice from which both eyes had been removed. When donor mice of the AKR strain were used, the detailed patterns of the transplant projections to the host brain were demonstrated with an antibody to Thy‐1.1, which specifically stains neural tissue derived from AKR donors. Many of the subcortical visual centers were innervated, and only small differences were encountered between anophthalmic and eye‐enucleated mice. The terminal arbors of transplant‐derived axons could not be classified as in normal animals, although several distinct arbor types were seen. In the superior colliculus, the laminar arrangements that characterize normal retinal arbors were disrupted. Despite this, the synaptic patterns formed by transplant derived axons in the superior colliculus of anophthalmic mice compared very closely with those of retinal axons in normal, sighted animals. These observations indicate that the ability of a retinal transplant to innervate the host brain and to form the synaptic arrays characteristic of optic terminals are not dependent on prior innervation, nor do they appear to be influenced by the events that follow eye removal. (e) 1993 Wiley‐Liss, Inc.
NGF receptor (p75)‐immunoreactivity in the developing primate basal ganglia
Authors: Kordower Jeffrey H. , Mufson Elliott J.
Published: January 2005

The distribution of the p75 nerve growth factor receptor (NGFr) was determined within the developing human basal ganglia in specimens between weeks 16 through 40 of gestation, 5 years of age, and adulthood. Although NGFr‐immunoreactive neurons were rarely seen in the caudate nucleus, a few such neurons were seen in the putamen between prenatal weeks 16 and 26 of development. At 26 and 40 weeks of gestation, the putamen also displayed NGFr‐immunoreactive fibers of putative basal forebrain origin. Some of these fibers coursed through the putamen en route to the cortex while others appeared to remain within the putamen. The external segment of the globus pallidus contained dense collections of NGFr‐immunoreactive neurons between 16 and 26 weeks of gestation, whereas the internal segment was devoid of immunoreactive perikarya. A few NGFr‐immunoreactive neurons were observed within the globus pallidus at embryonic week 40. The expression of NGFr‐immunoreactive neurons within the external segment of the globus pallidus was paralleled by a dense granular NGFr‐immunoreactive terminal‐like staining pattern within the subthalamic nucleus. This staining pattern was most intense at midgestation (weeks 21–26) and was not observed at 40 weeks of gestation or in adulthood. Interestingly, a similar NGFr‐immunoreactive terminal‐like pattern was also observed within the monkey subthalamic nucleus at embryonic day 120. These data indicate that NGF receptor mediated mechanisms may underlie developmental processes within the primate basal ganglia. The absence of NGFr‐immunoreactive neurons within the caudate nucleus, and the paucity of such neurons in the putamen, suggests that NGF receptors play a limited role in primate neostriatal development. Alternatively, developmental events mediated through NGF receptors may occur prior to embryonic week 16. Furthermore, an NGFr/trophic interaction appears to underlie the development of the pallidal‐subthalamic nucleus pathway. 1993 Wiley‐Liss, Inc.
Ultrastructure of the extraocular photoreceptor in the genitalia of a butterfly, Papilio xuthus
Authors: Miyako Yumiko , Arikawa Kentaro , Eguchi Eisuke
Published: January 2005

This paper describes the ultrastructure of a sensory neuron found in the extraocular photoreceptive site on the butterfly genitalia. Our previous studies have shown that there are two pairs of the photoreceptive sites in a butterfly (four per individual). Each photoreceptive site is recognizable by a transparent area in the pigmented cuticle of the genitalia. From the nerve that extends from the transparent cuticle to the last abdominal ganglion, a sustained train of single unit spikes can be recorded in response to a light flash. The single unit spikes disappear when the transparent cuticle is covered, thus indicating that a single photoreceptor exists close to it.

Here, we examined complete serial semithin sections of plastic‐embedded photoreceptive sites of both male and female, and observed an ovoid structure close to the transparent cuticle. The structure contained the cell body of a sensory neuron whose axon was in the nerve branch from which the photoresponse had been recorded. Further electron microscopy revealed that the cell body extended a few distal processes that protrude tubular membrane from the tip, forming a structure resembling the phaosome (from Greek;phaos = light, some = body) which was first described in the earthworm dermal photoreceptors. The sensory neuron was also found in a surgically isolated nerve‐photoreceptor preparation that responded to the light. We therefore propose that the phaosome‐containing sensory neuron is the butterfly genital photoreceptor. 1993 Wiley‐Liss, Inc.