bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial and temporal expression identify dromyosuppressin as a brain‐gut peptide in Drosophila melanogaster
Authors: McCormick J. , Nichols R.
Published: January 2005

The Drosophila dromyosuppressin peptide (TDVDHVFLRFamide) is a member of a family of peptides containing the common C‐terminal sequence ‐ RFamide. Dromyosuppressin shares a high degree of sequence homology with leucomyosuppressin isolated from cockroach (pEDVDHVFLRFamide) and identity with neomyosuppressin isolated from fleshfly. By means of sequence‐specific antisera, the cellular expression pattern of dromyosuppressin immunoreactive material was determined for all stages of Drosophila development.

Dromyosuppressin immunoreactivity first appears in two cells of the medial protocerebrum in embryos. The larval stage is characterized by an increase in the number of dromyosuppressin immunoreactive cells in the brain and the first appearance of cellular expression in the ventral ganglion. Immunoreactive fibers extend from the medial protocerebrum cells into the ventral ganglion. Relative to the larval stage, the pupal and adult stages are marked by an increase in the number of immunoreactive cells in the central nervous system and an increase in the arborization of immunoreactive fibers extending from these cells.

Immunoreactivity is present in larvae in two cells near the anus; in the adult gut, expression is observed in two cells in the rectum and immunoreactive fibers in the crop that appear to extend from the central nervous system. In general, the number of cells containing dromyosuppressin immunoreactive material increases throughout Drosophila development. However, expression in three cells is restricted to specific developmental periods. These data identify dromyosuppressin as a brain‐gut peptide regulated at both a cellular and developmental level. © 1993 Wiley‐Liss, Inc.
Comparative efficacy of expression of genes delivered to mouse sensory neurons with herpes virus vectors
Authors: Davar G. , Kramer M. F. , Garber D. , Roca A. L. , Andersen J. K. , Bebrin W. , Coen D. M. , Kosz‐Vnenchak M. , Knipe D. M. , Breakefield X. O. , Isacson O.
Published: January 2005

To achieve gene delivery to sensory neurons of the trigeminal ganglion, thymidine kinase‐negative (TK−) herpes simplex viruses (HSV) containing the reporter gene lacZ (the gene for E. coli β‐galactosidase) downstream of viral (in vectors RH116 and tkLTRZ1) or mammalian (in vector NSE‐lacZ‐tk) promoters were inoculated onto mouse cornea and snout.

Trigeminal ganglia were removed 4, 14, 30, and 60 days after inoculation with vectors and histochemically processed with 5‐bromo‐4‐chloro‐3 indolyl‐beta‐galactoside (X‐Gal). With vector tkLTRZ1, large numbers of labeled neurons were observed in rostromedial and central trigeminal ganglion at 4 days after inoculation. A gradual decline in the number of labeled neurons was observed with this vector at subsequent time points. With vectors RH116 and NSE‐lacZ‐tk, smaller numbers of labeled neurons were seen at 4 days following inoculation than were observed with vector tkLTRZ1. No labeled neurons could be observed at 14 days after inoculation with vectors RH116 and NSE‐lacZ‐tk.

Immunocytochemistry for E. coli β‐galactosidase and in situ hybridization to HSV latency‐associated transcripts revealed labeled neurons in regions of the trigeminal ganglion similar to that observed with X‐Gal staining. A comparable distribution of labeled neurons in trigeminal ganglion was also observed after application of the retrograde tracer Fluoro‐Gold to mouse cornea and snout.

These data provide evidence that retrogradely transported tk− herpes virus vectors can be used to deliver a functional gene to sensory neurons in vivo in an anatomically predictable fashion. © 1994 Wiley‐Liss, Inc.
The unipolar brush cell: A neglected neuron of the mammalian cerebellar cortex
Authors: Mugnaini Enrico , Floris Alessandra
Published: January 2005

We describe with a variant of the Golgi method a new type of neuron that is prominently represented in the granular layer of the mammalian vestibulocerebellum but is presently neglected in all major accounts on the cerebellum. These neurons, here termed unipolar brush cells, are intermediate in size between granule cells and Golgi cells. They typically have a thin and presumably myelinated axon, and a single and stubby dendrite whose tip forms a tightly packed group of branchlets resembling a paintbrush. The branchlets often intertwine with the digitiform claws of granule cell dendrites and are occasionally approached by Golgi cell dendrites, indicating that the unipolar brush cells may share the input of the other granular layer neurons. Branchlets of neighboring unipolar brush cells converging into the same neuropil island also occur. The brush‐like tip of the unipolar cell engulfs one or two mossy fiber rosettes to form an extensive synapse that appears to close recurrent loops involving the vestibular nuclei. Positive feedback in these loops could help to explain several motor responses and drive mechanisms of extended duration that are controlled by the ventral cerebellum. © 1994 Wiley‐Liss, Inc.
In vitro modulation of somatic glycine‐like immunoreactivity in presumed glycinergic neurons
Authors: Wickesberg Robert E. , Whitlon Donna , Oertel Donata
Published: January 2005

Previous studies indicate that tuberculoventral and cartwheel cells in the dorsal cochlear nucleus as well as a group of stellate cells in the ventral cochlear nucleus are likely to be glycinergic. To test whether these neurons contain higher levels of free glycine than cells that are probably not glycinergic, immunocytochemical studies with antibodies against glycine conjugates were undertaken on slices of the murine cochlear nuclear complex. Present results show that the cell bodies of all three groups of neurons are immunolabeled. However, the somatic labeling of the tuberculoventral and cartwheel cells can be modulated by experimental conditions. In slices fixed immediately after cutting, many cell bodies in the deep layer of the dorsal cochlear nucleus (DCN), presumably tuberculoventral neurons, are labeled. As a slice is incubated in vitro, cell bodies in the deep layer of the DCN lose their glycine‐like immunoreactivity. After 7 hours in vitro, labeled cells are absent in the deep DCN, but the immunoreactivity can be regained by electrically stimulating the auditory nerve for 20 minutes. The loss of immunoreactivity is prevented by electrical stimulation, by axotomy, and by inclusion of 0.8 μM tetrodotoxin, or 1 μM strychnine, or 50 μM colchicine or 50 μM μ‐lumicolchicine in the bathing saline. Cartwheel cells retain their immunoreactivity during incubation in vitro without electrical stimulation, but lose it under two conditions. One is following a cut across the ventral cochlear nucleus (VCN) that severs most of their granule cell input, and the other is the inclusion of tetrodotoxin in the bathing saline. The labeling of cell bodies in the ventral cochlear nucleus and of puncta and processes is not changed by any of these experimental manipulations. © 1994 Wiley‐Liss, Inc.
Morphology of developing rat genioglossal motoneurons studied in vitro: Changes in length, branching pattern, and spatial distribution of dendrites
Authors: Nüñez‐Abades P. A. , He F. , Barrionuevo G. , Cameron W. E.
Published: January 2005

The aim of this study is to describe the postnatal change in dendritic morphology of those motoneurons in the hypoglossal nucleus that innervate the genioglossus muscle. Forty genioglossal (GG) motoneurons from four age groups (1–2, 5–6, 13–15, and 19–30 postnatal days) were labeled by intracellular injection of neurobiotin in an in vitro slice preparation of the rat brainstem and were reconstructed in three‐dimensional space.

The number of primary dendrites per GG motoneuron was ∼6 and remained unchanged with age. The development of these motoneurons from birth to 13–15 days was characterized by a simplification of the dendritic tree involving a decrease in the number of terminal endings and dendritic branches. Motoneurons lost their 6th–8th order branches, in parallel with an elongation of their terminal dendritic branches maintaining the same combined dendritic length. The elongation of terminal branches was attributed to both longitudinal growth and the apparent lengthening caused by resorption of distal branches. The elimination of dendritic branches tended to increase the symmetry of the tree, as revealed by topological analysis. Later, between 13–15 days and 19–30 days, there was a reelaboration of the dendritic arborization returning to a configuration similar to that found in the newborn. The length of terminal branches was shorter at 19–30 days, while the length of preterminal branches did not change, suggesting that the proliferation of branches at 19–30 days takes place in the intermediate parts of terminal branches.

The three‐dimensional distribution of dendrites was analyzed by dividing space into six equal volumes (hexants). This analysis revealed that GG motoneurons have major components of their dendritic tree oriented in the lateral, medial, and dorsal hexants. Further two‐dimensional polar analysis (consisting of eight sectors) revealed a reconfiguration of the tree from birth up to 5–6 days involving resorption of dendrites in the dorsal, dorsomedial, and medial sectors and growth in the lateral sector. Later in development (between 13–15 days and 19–30 days), there was growth in all sectors, but of a greater magnitude in the dorsomedial, medial, and dorsolateral sectors. © 1994 Wiley‐Liss, Inc.
Close appositions between Tyrosine hydroxylase immunoreactive boutons and respiratory neurons in the rat ventrolateral medulla
Authors: Sun Qi‐Jian , Pilowsky Paul , Minson Jane , Arnolda Leonard , Chalmers John , Llewellyn‐Smith Ida J.
Published: January 2005

The extent of the adrenergic input to respiratory neurons in the ventrolateral medulla oblongata of rats was assessed by using a combination of intracellular recording, dye filling, and immunohistochemistry. Twenty‐two neurons that displayed a pronounced respiration‐related modulation of their membrane potential, and could not be antidromically activated by electrical stimulation of the superior laryngeal, vagus, or facial nerves, were labelled by intracellular injection of biocytin. Three types of respiration‐related neurons were labelled: small neurons located in the Bötzinger complex between 0.5 and 1.0 mm caudal to the facial nucleus; medium‐sized neurons located in the ventral respiratory group 1.0 to 2.0 mm caudal to the facial nucleus; and large motoneurons located within the nucleus ambiguus 0.5 to 2.0 mm caudal to the facial nucleus. Small Bötzinger neurons [length = 22 ± 5 μm, width = 13 ± 3 μm, area = 222 ± 79 μm2; (mean ± SD, n = 5)] had membrane potentials of − 15 to − 27 mV during the recording period. Four of five of these cells had profuse axonal terminations between 50 μm caudal and 450 μm rostral to their somata, suggesting that they may form part of local networks responsible for generating respiratory activity. Medium‐sized ventral respiratory group neurons (length = 26 ± 5 μm, width = 18 ± 4 μm, area = 377 ± 141 μm2; n = 5) were found in the vicinity of the nucleus ambiguus dorsal to the lateral reticular nucleus. Three of five of these neurons had an axon that crossed the midline and travelled caudally. One axon had a collateral with varicosities close to its soma. The somata of motoneurons (length = 29 ± 6 μm, width = 21 ± 4 μm, area = 485 ± 142 μm2; n = 12) were located within the nucleus ambiguus, and had axons that could be traced to exit points from the medulla. Tyrosine hydroxylase immunoreactive cells and their terminal fibres within the medulla were localised by immunocytochemistry. Small Bötzinger neurons received the largest number of close appositions from tyrosine hydroxylase immunoreactive boutons (13 ± 2 appositions/neuron; n = 5). Medium‐sized ventral respiratory group neurons received fewer appositions (8 ± 4 appositions/neuron; n = 5). Most motoneurons (n = 10) received few appositions from tyrosine hydroxylase immunoreactive boutons, while two received none. The average number was 3 ± 3 appositions/neuron (n = 12). On all neurons, appositions occurred most commonly on small dendrites rather than large proximal dendrites. Axosomatic appositions were never seen. These results suggest that catecholamine‐containing nerve fibres may provide a direct synaptic input to small respiration‐related neurons that are thought to be involved in the generation of central respiratory activity. A catecholamine input to these neurons could provide a basis for the previously observed effects of noradrenaline on respiratory frequency. © Wiley‐Liss, Inc.
Differential response of neutral endopeptidase 24.11 (“enkephalinase”), and cholinergic and opioidergic markers to hypoglossal axotomy
Authors: Back Stephen A. , Gorenstein Charles
Published: January 2005

Neutral endopeptidase 24.11 (NEP; “enkephalinase”) may inactivate a number of centrally active neuropeptides including the enkephalins and substance P. In most areas of the central nervous system, the cell types which express NEP activity are not known. The hypoglossal nucleus (N. XII) was selected as a model system to characterize the cytochemical localization of NEP. The effect of hypoglossal nerve axotomy upon the distribution of NEP activity in the hypoglossal nucleus was compared to the effect upon cholinergic markers, the muopiate receptor, and the enkephalins.

By use of a fluorescence histochemical method, NEP was localized at all levels of N.XII to
the soma and proximal processes of the majority of the apparent motor neurons in the nucleus.
Fluorescent double‐labeling studies revealed the presence of numerous enkephalinergic
varicosities which localized to the neuropil surrounding NEP‐stained motor neurons. To
determine whether NEP was synthesized by these motor neurons, 18 rats received a unilateral
transection of the hypoglossal nerve. A pronounced decrease in NEP staining in N.XII was
observed on the operated side as early as 3 days following axotomy. This decrease persisted at all
levels of the nucleus for about 5 weeks. By 7 weeks, the staining between the control and
operated sides was indistinguishable. By contrast, there was no apparent change in the density
or distribution of enkephalin‐immunoreactive varicosities in five animals examined 6 to 32 days
following axotomy. Radioligand binding of [3H]DAMGO to the μ‐opiate receptor in N.XII was
studied in 20 animals by quantitative autoradiography at 2, 6, and 11 days after axotomy. No
significant changes in the level of radioligand binding to the μ‐receptor were detected in
response to axotomy. In contrast to the opiate system, the cholinergic enzymes choline
acetyltransferase, acetylcholinesterase, and pseudocholinesterase showed a coordinate decrease
in motor neuron‐associated staining on the operated side of N.XII at 3 ,6 , and 11 days following
axotomy which paralleled the decrease in NEP staining. By contrast, the lysosomal enzyme
marker, acid phosphatase, showed a pronounced increase in staining on the operated side.

The results of this study are consistent with the synthesis of NEP by cholinergic N.XII motor neurons and indicates that the enkephalins and NEP in N.XII are closely associated, but derive from separate neuronal populations. The widespread overlap in the distribution of NEP‐stained motor neurons and enkephalinergic varicosities in N.XII provides additional anatomical support for a potential role for NEP in the inactivation of centrally active enkephalins. The apparently stable levels of the enkephalins and μ‐opiate receptor after axotomy, in contrast to the coordinate decrease in cholinergic enzyme staining, suggest a differential regulation of the opiate and cholinergic systems in response to axotomy. © 1994 Wiley‐Liss, Inc.
Central terminations of low‐threshold mechanoreceptive afferents in the trigeminal nuclei interpolaris and caudalis of the cat
Authors: Miyoshi Y. , Suemune Setsuko , Yoshida Atsushi , Takemura Motohide , Nagase Yoshitaka , Shigenaga Yoshio
Published: January 2005

Previous studies indicate that vibrissa, nonvibrissa, guard hair, hairy skin, and periodontal ligament afferents give rise to morphologically distinct terminal arbors in the trigeminal nuclei principalis (Vp) and oralis (Vo) in the cat. The present study describes the extent to which morphological and functional relationships exist in the nuclei interpolaris (Vi) and caudalis (Vc). Twenty‐two fibers were physiologically characterized and stained by intra‐axonal HRP injection techniques. The fast adapting (FA) vibrissa (VF) afferents gave rise to compact and circumscribed arbors in Vj and Vc. These tended to be larger in Vc than in Vi. The slowly adapting (SA) vibrissa (VS) afferents in Vi and Vc had more widespread and larger arbors than those of the VF afferents. The VS arbors in Vc tended to be larger and less circular than those in Vi. Guard hair (GH) afferents gave rise to circumscribed arbors in both nuclei, but those in Vc tended to have larger and more circular arbors than those in Vi. Down hair (DH) afferents gave rise to small, circumscribed arbors or a few distinct patches of boutons within a small area in Vi; arbors in Vc were less extensive and “stringy.” Unlike other afferents, DH arbors were larger in Vi than in Vc, but smaller than those of GH afferents in either nuclei. The SA hairy skin (SS) afferents had arbors that were widespread with a few distinct patches of boutons; the arbors in Vc were larger than those in Vi. The arbors of SS afferents were smaller than those of VS and GH afferents in both nuclei. Like GH afferents, FA periodontal ligament (PF) afferents gave rise to large and circumscribed arbors in Vi, although the arbors in Vc were smaller and less dense. The present study demonstrated significant functional and morphological relationships for primary afferents in Vi and Vc, thus suggesting that sensory information from each of the distinct fiber or functional classes is processed in a characteristic manner in the individual nuclei. © Wiley‐Liss, Inc.
Human fetal neocortical tissue grafted to rat brain cavities survives, leads to reciprocal nerve fiber growth, and accumulates host IgG
Authors: Humpel Christian , Bygdeman Marc , Olson Lars , Strömberg Ingrid
Published: January 2005

The human‐to‐rat xenograft approach offers possibilities to study aspects of primate cortex development and function without monkeys. Human fetal cortical tissue was grafted to prepared cortical cavities of immunosuppressed host rats. Fetal tissue fragments were collected after routine low‐pressure vacuum aspiration abortions performed in the first trimester of gestation. Human derived neurons and human nerve fiber outgrowth were visualized by immunohistochemistry with antibodies against human neurofilament protein 70 kD (hNFP70). Ingrowth from rat host striatum or cortex into the grafts was analyzed by immunohistochemistry with antibodies against tyrosine hydroxylase. Astrocytes were evaluated by immunohistochemistry with antibodies against glial fibrillary acidic protein. The grafts grew into different sizes (1–10 mm in diameter) and contained large numbers of hNFP70‐positive nerve fibers. All grafts gave rise to outgrowth of hNFP70‐positive fibers into the host with partly a cortical layering; layers III and IV received a majority of the human fibers. In several cases, the graft‐derived nerve fibers entered the host brain at restricted areas, while there was no crossing over of nerve fibers at the rest of the graft‐host interface. Tyrosine hydroxylase‐positive fibers were usually not abundant in the grafts. Interestingly, cases of massive ingrowth occurred from host striatum into the graft in a pattern suggesting “permissive sites” at the graft‐host interface in the same way as outgrowth from graft to host was found. Additionally, tyrosine hydroxylase‐immunoreactive fibers from host cortex were found to grow into the transplant. Glial fibrillary acidic protein immunoreactivity was increased at the interfaces between graft and host cortex or host striatum. Immunohistochemistry using antibodies against rat IgG indicated the presence of rat IgG within the grafts, and in bordering areas of host brain, possibly indicating a defective graft‐host barrier. Taken together, these results show that human cortical‐tissue pieces grafted to cortical cavities of immunosuppressed rats survive grafting and develop, and that reciprocal nerve fiber growth between grafts and hosts occur. Human cortical neurons can grow into the rat host brain in a pattern which is partly determined by host cortical architecture. © Wiley‐Liss, Inc.
Differential distribution of amyloid protein precursor immunoreactivity in the rat brain studied by using five different antibodies
Authors: Beeson James G. , Shelton Earl R. , Chan Hardy W. , Gage Fred H.
Published: January 2005

The β‐amyloid or A4 protein is found deposited in neuritic plaques and neurofibrillary tangles in Alzheimer's disease (AD) affected brains and in the brains of adults with Down's Syndrome. The precursor to this 42 amino acid protein is the 695 amino acid long amyloid protein precursor (APP‐695). Two additional APP species, APP‐751 and APP‐770, each contain a 56‐amino‐acid insert sequence that is analogous to Kunitz protease inhibitors. APP mRNA is widely distributed in both the human and rat brain, although the adult rat does not develop mature amyloid pathology. In this study we used antibodies against the N‐terminus, junction site (unique to APP‐695) insert sequence (unique to APP‐751,‐770), A4 region, and C‐terminus of APP to immunolabel sections from throughout the young adult rat brain. From these results we constructed maps of the staining pattern of each antibody. We found that APP is widely distributed throughout the brain, that labelling is predominantly neuronal in character, and that there is marked variation among the antibodies in the extent of labelling, the particular cell populations stained, and the structures labelled within individual cells. The differential staining patterns observed with the five different antibodies suggest that the way APP is processed differs from one region to another and within different compartments in the cell. The specificity of the antibodies was established by Western blot analysis, in which APP species of approximately 95 and 110 kD were found. Our findings on the distribution of APP provide a foundation for further investigations into the normal role of APP and the pathogenesis of AD. © 1994 Wiley‐Liss, Inc.
Interplay between the dendritic trees of alpha and beta ganglion cells during the development of the cat retina
Authors: Deplano S. , Ratto G. M. , Bisti S.
Published: January 2005

We have analyzed the effect of a small lesion to the retina of a two‐day‐old kitten and observed that after degeneration of ganglion cells whose axons were severed, a restricted region of the retina remained depleted of cells. Cells located near the borders of the depleted zone showed an abnormal elongation of dendrites towards the bare area. By means of a computer‐aided system, we analyzed the whole population of cells at the two borders, and in agreement with previous data found that the effect was most prominent at the border and progressively decreased to eventually disappear at a distance of approximately 500 μm. The distance from the border, however, is not the only factor to influence the degree of asymmetry; with comparable distances, the vicinity of an α‐cell reduces the projection of the β‐cell dendrites toward the empty area. We suggest that the organization of the adult retinal pattern is also influenced by interactions occurring between dendrites of different classes of ganglion cells. © 1994 Wiley‐Liss, Inc.
Development of interneurons with ipsilateral projections in embryonic rat spinal cord
Authors: Silos‐Santiago Inmaculada , Snider William D.
Published: January 2005

Considerable progress has been made in recent years in identifying molecules with restricted expression in mammalian spinal cord at early developmental stages. However, the significance of the different expression patterns for most of these molecules is nuclear because so little is known about the development of various classes of spinal interneurons. Recently, we have characterized the development of rat spinal cord interneurons with an axon that crosses in the ventral commissure (Silos‐Santiago and Snider, J. Comp. Neurol., 325:514, 1992). In the current study, we describe the morphological development of ipsilaterally projecting spinal interneurons in laminae V–VIII of the thoracic spinal cord. These neurons were labelled by retrograde lateral diffusion of DiI after crystals were placed in various locations in the embryonic thoracic cord.

By E14, approximately 48 hours after the first interneurons are generated, eight different groups of ipsilateral interneurons are present in the spinal cord. By E15, these groups of ipsilateral interneurons have reached distinct locations within the gray matter. Even at this early stage, different groups of cells have elaborated characteristic dendritic arborizations. By E19, at least 17 different types of ipsilateral interneurons can be identified on the basis of location and dendritic morphology. In general, ipsilateral interneurons are located more dorsally and laterally than commissural interneurons at all stages of embryonic development. Furthermore, in comparison with commissural neurons, fewer ipsilateral interneurons have dendritic arbors with a mediolateral orientation in the transverse plane.

This work demonstrates that rat embryonic spinal cord contains a large number of morphologically distinct classes of interneurons that extend axons into the ipsilateral lateral funiculus. These neurons can be distinguished from commissural neurons on the basis of location and morphology. These results, taken together with those from our previous study, provide a framework for the localization of gene expression to different classes of spinal interneurons at early developmental stages. © 1994 Wiley‐Liss, Inc.
Hindlimb sensory neuron number increases with body size
Authors: St. Wecker Peter G. R. , Farel Paul B.
Published: January 2005

As an animal grows, its sensory systems face the task of maintaining sensitivity and discrimination in peripheral fields that are continually enlarging. Without the addition of neurons, existing cells would have to innervate a wider skin area, leading to a decrease in the precision with which stimuli are localized. Neurons were counted in the three dorsal root ganglia (DRGs) that innervate the hindlimb of the bullfrog (Rana catesbeiana). Profiles of neuronal nuclei containing the single nucleolus found in these cells were counted in every third section of serially cut ganglia. This means of assessing neuron number was validated by comparing these profile counts with three‐dimensional reconstructions of sensory neurons. Large frogs (10–17 cm) had more than twice as many DRG neurons as small frogs (3.3–5 cm). The rate of increase was greatest between 3 and 8 cm, when over 1,300 hindlimb sensory neurons were added for each 1 cm increase in body length. The possibility that selective survival of frogs with many neurons biases estimates of mean neuron number was ruled out by the finding that frogs drawn from the same closed population, half of which were sacrificed immediately and half of which were sacrificed after 1 year's survival, showed expected differences in neuron number. Horseradish peroxidase applied to particular hindlimb nerves retrogradely labeled more neurons in large frogs than small frogs, supporting the hypothesis that added neurons extend their axons to the periphery.

No evidence of tritium labeling was found following injection of 3H‐thymidine (a marker of DNA synthesis) every third day for 20–22 weeks, a period over which, on the basis of changes in body length, substantial numbers of neurons were likely added. These results, combined with previous studies of motoneuron addition in the lumbar lateral motor column, are consistent with the hypothesis that the population of sensory neurons is augmented by late differentiation of existing precursor cells. © 1994 Wiley‐Liss, Inc.
Quantitative morphological analysis of the cerebellar nuclei in normal and lurcher mutant mice. I. Morphology and cell number
Authors: Heckroth John A.
Published: January 2005

The present study indicates that the cerebellar nuclei of the mouse are essentially identical in structure with those described in the rat, and that the atrophic cerebellar nuclei in lurcher mutant mice exhibit a comparable anatomical organization. A quantitative estimate of the atrophy observed in the cerebellar nuclei of the adult lurcher mutant mouse reveals an overall 60% decrease in volume. Cell counts in the wild‐type cerebellar nuclei reveal a total of 8,528 principal neurons and 10,203 small neurons. The ratio of small/principal neurons is 0.5 in the fastigal nucleus and between 1 and 1.5 in other subdivisions. In lurcher, the principal neurons are slightly reduced in number (−20%) in the nuclear complex, while the population of small neurons is reduced by 37% in the interposed and dentate nuclei, but is unchanged in the fastigal nucleus. These results suggest that the massive deafferentation of the cerebellar nuclei that occurs between 10 and 30 days of age in lurcher mutants has a relatively mild effect on the principal cerebellar nuclear neurons. In the population of small neurons, however, the effect of deafferentation may be exacerbated by a secondary retrograde transneuronal degeneration brought on by the severe degeneration of inferior olivary neurons and cerebellar cortex in this mutant. © 1994 Wiley‐Liss, Inc.
Distribution of myomodulin‐like immunoreactivity in the adult and developing ventral nervous system of the locust Schistocerca gregaria
Authors: Swalles Lesley S. , Evans Peter D.
Published: January 2005

The distribution of myomodulin‐like immunoreactivity in the ventral nervous system of an insect, the locust Schistocerca gregaria, both in the adult and during development, is described. The result suggest the presence of a novel modulatory system in insects which uses myomodulin‐like neuropeptides. The study also indicates that the myomodulins, which were first identified in mollusks, may represent another interphyletic family of neuropeptides.

In the suboesophageal ganglion, immunoreactive cells occur in five groups. The processes from the two anterior ventral midline groups of cells projects to the corpora allata via nervi corpora allata II. Thus myomodulin‐like neuropeptides may be involved in the control of the release of juvenile hormone from the corpora allata.

The thoracic ganglia contain three groups of immunoreactive cells, including a bilaterally symmetrical group of 12–15 posterior lateral cells, which project to the median nerve and its neurohaemal organs, suggesting a possible neurohaemal role for myomodulin‐like peptides. Each thoracic neuromere also contains a single, intensely stained, dorsal unpaired median (DUM) cell that may correspond to the so‐called H cell. In the abdominal ganglia, the staining shows sexual dimorphism, both in terms of the number of dorsal and ventral midline cells stained and in terms of the distribution of their immunoreactive processes.

Myomodulin‐like immunoreactivity is one of the earliest neurotransmitter/neurohormone phenotypes detectable during the development of the locust nervous system. It first appears in the single DUM cells in each of the thoracic neuromeres at 50% development, and the complete adult pattern of staining is present at 85%‐90% of development. © 1994 Wiley‐Liss, Inc.
Synaptic innervation of neurons in the internal pallidal segment by the subthalamic nucleus and the external pallidum in monkeys
Authors: Smith Y. , Wichmann T. , DeLong M. R.
Published: January 2005

In order to better understand the way by which the subthalamic nucleus interacts with the globus pallidus to control the output of the basal ganglia, we carried out a series of experiments to investigate the pattern of synaptic innervation of the pallidal neurons by the subthalamic terminals in the squirrel monkey. To address this problem we used the anterograde transport of biocytin.

Following injections of biocytin in the subthalamic nucleus, rich plexuses of labelled fibres and varicosities formed bands that lay along the medullary lamina in both segments of the ipsilateral pallidum. At the electron microscopic level, two populations of bioctyin‐containing terminals were identified in the internal pallidum (GPi). A first group of small to medium‐sized terminals (type 1) mean cross‐sectional area ±S. D. = 0.41 ± 0.04 μm2contained round vesicles and formed asymmetric synapses with dendritic shafts (95%) of mixed sizes (maximum diameter ranging from 0.3 to 4.0 μm) and spine‐like structures (5%). This second group of terminals (type 2) contained pleiomorphic vesicles, had a larger cross‐sectional area (mean ± S. D. = 0.9 ± 0.4 μm2) and formed symmetric synapses predominantly with perikarya (41%) and large dendrites (57%). In some cases, the two types of terminals converged at the level of single GPi neurons. Postembedding immunogold method revealed that the type 2 terminals displayed gamma‐aminobutyric acid (GABA) immunoreactivity, whereas the type 1 terminals did not. In the external pallidum (GPe), injections in the subthalamic nucleus labelled both type 1 or type 2 terminals. However, the labelled type 2 boutons were much less abundant in GPe than in GPi. The presence of biocytin‐labelled perikarya in GPe and the fact that the type 2 terminals displayed GABA immunoreactivity led us to suspect that these terminals were derived from axons of GPe neurons. In agreement with this hypothesis, injctions ofPhaseolus vulgaris‐leucoagglutinin (PHA‐L) in GPe labelled terminals in GPi that displayed the morphological features and a pattern of synaptic organization similar to the type 2 terminals.

In conclusion, the results of our study demonstrate that the subthalamopallidal terminals form asymmetric synapses that are distributed along the dendritic tree of GPe and Gpi neurons. In contrast, the GPe projection to GPi give rise to large GABA‐containing terminals that form symmetric synapses predominantly with the proximal region of pallidal neurons. Because the GABAergic axon terminals from GPe form synapses onto the perikarya and proximal dendrites of GPi neurons, the Gpe input is in a strategic position to reduce the excitatory influence generated more distally on the dendritic tree by the subthalamic nucleus. © 1994 Wiley‐Liss, Inc.
Differential expression of keratins in goldfish optic nerve during regeneration
Authors: Fuchs Chana , Druger Robert K. , Glasgow Eric , Schechter Nisson
Published: January 2005

The goldfish visual pathway, unlike the visual pathway of higher vertebrates, retains continuous growth and development throughout life and is capable of functional regeneration. The structure and expression of proteins that support the physiological attributes of this system are of interest. Glial cells in this pathway express keratins as the predominant intermediate filament proteins rather than the expected glial fibrillary acidic protein. Previously we identified and characterized cDNA clones representing two type I keratins from the goldfish optic nerve, GK48 and GK49. The GK48 protein is the type I keratin partner to the type II keratin ON3, while the GK49 protein is expressed in a different cell type. Here, we extend our studies on the expression of mRNA for the GK48, GK49, and ON3 proteins at the early stages of optic nerve regeneration. Rnase protection assays show that at 10 days post‐crush, there is no overall change in levels of mRNA for these proteins as compared to uncrushed control nerves and nerves from unoperated fish. In addition, we show by in situ hybridization that the GK49 protein shows no changes in its distribution of mRNA in the optic nerve after crush. In contrast, the level of GK48 and ON3 mRNA are greatly reduced within the crush zone. However, these two mRNAs are differentially expressed at different time points during regeneration, with GK48 mRNA appearing in the crush zone before ON3. These results indicate that the mRNA for the GK48 and ON3 proteins are differentially regulated during regeneration and that these two proteins are expressed in a different cell type from the GK49 protein. © 1994 Wiley‐Liss, Inc.
Localization of immunoreactive ubiquitin in the nervous system of the Manduca sexta moth
Authors: Fahrbach S. E. , Schwartz L. M.
Published: January 2005

Selective neuronal death is a normal component of metamorphosis in the moth, Manduca sexta. In particular, the three unfused abdominal ganglia of the ventral nerve cord serve as a useful experimental preparation in which to study the regulation of the molecular mechanisms that mediate programmed cell death. Ubiquitin, a highly conserved 76‐amino acid protein found in all eukaryotic cells, has previously been shown to be present in increased amounts in some tissue undergoing programmed cell death (e. g., larval intersegmental muscles inManduca sextamoths, dying cells in developing tunicates), but not in others (T‐cells, Drosophila ommatidial cells, cultured sympathethic neurons deprived of nerve growth factor). It has been hypothesized that the need for ubiquitin‐dependent proteolysis is increased in dying cells, and that the accumulation of ubiquitin might serve as an early marker for cells commited to die. Immunohistochemical localization of ubiquitin at the light microscopic level in the adbominal gaglia of Manduca sextasuggests that this protein plays a number of important roles in neuronal physiology and may be associated with the death of some neurons in this tissue. The most intense staining of neuronal cytoplasm, however, was found not in dying neurons, but instead in sets of persisting neurons that may serve a primarily neurosecretory or neuromodulatory function. The staining obtained in these cells with antibodies directed against ubiquitin was developmentally regulated. © 1994 Wiley‐Lisx, Inc.
Monoamine receptors in the amygdaloid complex of the tree shrew (Tupaia belangeri)
Authors: Flügge Gabriele , Ahrens Olaf , Fuchs Eberhard
Published: January 2005

Although it is well known that the mammalian amygdala comprises a heterogeneous complex of cytoarchitectonically and histochemically distinct nuclei, the association of these nuclei with different monoamine systems has not been described in detail. We therefore investigated the pattern of receptors for monoamines in the amygdala of the tree shrew (Tupaia belangeri). Binding sites for the α2‐adrenoceptor ligand (3H) rauwolscine, the α1‐adrenoceptor ligand (3H) prazosin, the β‐adrenoceptor ligand (125I) iodocyanopindolol, and the serotonin1A‐receptor ligand (3H) 8‐hydroxy‐2 (di‐n‐propylamino) tertralin were visualized by in vitro autoradiography, and anatomically localized by comparing the autoradiograms to Nissl‐ and acetylcholinesterase‐stained sections. To characterize binding of the radioligands pharmacologically, displacement experiments with different specific competitors were performed.

Whereas the highest number of α2‐adrenergic binding sites was detected in the medial and the central nucleus as well as in the intercalated nueclei, the majority of serotonin1A binding sites was found in the magnocellular basal nucleus and the accessory basal nucleus, demonstrating a clear difference in the anatomy of the α2‐adrenergic and the serotonin1A receptor systems. In contrast, the pattern of α1‐adrenoceptor binding partially overlaps with that of both former receptor types. While the number of α‐adrenergic and serotonin1A binding sites is relatively high in the tree shrew amygdala, there is only a low number of β‐adrenergic binding sites in most nuclei. However, in the cortical nuclei, moderate to high numbers of binding sites for all radioligands are present. Therefore, according to our data on the tree shrew amygdala, which is anatomically similar to the amygdala of cats and primates, α2‐adrenoceptors cover primarily the medial part of the amygdaloid formation and serotonin1A‐receptors predominantly occupy the basal nuclei, whereas α1‐adrenoceptors are present in both parts of the formation. © 1994 Wiley‐Liss, Inc.
Synaptic organization of regenerated retina in the goldfish
Authors: Hitchcock Peter F. , Cirenza Paul
Published: January 2005

In the adult goldfish, any manipulation that significantly depletes retinal neurons stimulates neurogenesis and the regeneration of nearly normal retina. We sought to determine the extent to which the regenerated neurons formed normal synaptic connections. We used qualitative and quantitative electron microscopy to compare the organization of the synaptic layers in regenerated and normal retinas. In eight eyes, a small patch of retina was surgically excised, stimulating regeneration of new retina in its place. Animals were killed 16–20 weeks after surgery. Qualitative comparisons of the synaptic architecture of photoreceptor terminals in the outer plexiform layer and quantitative comparisons of the synaptic organization in the inner plexiform layer were made between the patch of regenerated retina and an adjacent intact site. In the regenerated outer plexiform layer, cone pedicles and rod spherules were not arranged as regularly as normal, but they formed normal‐appearing synaptic contacts. In the regenerated inner plexiform layer, with one exception, the quantitative descriptors of the synaptic organization in the normal and regenerate were n ot significantly different: The planimetric and numerical densities of the synapses, number of synapses/inner retinal neuron, and, with the exception of the bipolar terminals in the inner plexiform layer, and synapse depth profiles were similar. These data suggest that (1) relatively normal synaptic connections are recreated during regeneration, (2) the cellular mechanisms that guide synaptogenesis during development act during retinal regeneration, and (3) the physiological response properties of regenerated neurons should be comparable to that found in the normal retina. © 1994 Wiley‐Liss, Inc.
Distribution of the postsynaptic dorsal column projection in the cuneate nucleus of monkeys
Authors: Cliffer Kenneth D. , Willis William D.
Published: January 2005

Cells in the spinal cord that are postsynaptic to primary afferent fibers project to the dorsal column nuclei in the postsynaptic dorsal column pathway. The projection of cells in the cervical spinal cord of monkeys to the cuneate nucleus has been reported to avoid pars rotunda of that nucleus, the part that contains the somatotopic representation of the ipsilateral hand. We used the sensitive anterograde tracer Phaseolus vularis leucoagglutinin to reexamine this projection. We made multiple iontophoretic injections into the cervical enlargements of three monkeys (two Macaca fascicularis and one Macaca mulatta). Control injections were made in the contralateral dorsal columns of one of these and in the dorsal roots of a fourth animal (M. fascicularis) to test for transport by fibers of passage. After 28–39 days, the animals were deeply anesthetized and perfused, and the tissue was processed for immunohistochemical detection of the label. In all cases (excluding control injections), labeled fibers and varicosities were distributed widely in the ipsilateral cuneate and external cuneate nuclei, including pars rotunda. The dorsal column nuclei ipsilateral to control injections contained no label or only very few poorly labeled fibers, indicating that labeling through fibers of passage did not contribute importantly to the results. This study indicates that the postsynaptic projection to the cuneate nucleus is widespread and includes pars rotunda. Such projections may contribute to transmission of information originating in nociceptors through the dorsal column‐medial lemniscal system to the ventrobasal thalamus. © Wiley‐Liss, Inc.
Maturation of neuron types in nucleus of solitary tract associated with functional convergence during development of taste circuits
Authors: Mistretta Charlotte M. , Labyak Susan E.
Published: January 2005

Late fetal through postnatal development in sheep is a period of increasing convergence of afferent taste fibers onto second‐order neurons in the nucleus of the solitary tract (NST). To learn whether neuron morphology alters in concert with convergence and neurophysiological development in NST, three‐dimensional neuron reconstructions were made of cells in a functionally defined region of gustatory NST from Golgi preparations of the brainstem. Elongate, multipolar, and ovoid neurons were studied in fetuses from 85 days of gestation through the perinatal period (term = 147 days of gestation), to postnatal stages. Somal size and form, and dendritic complexity and extent, increased markedly from 85 to about 110 days of gestation in both of the proposed NST projection neurons, elongate and multipolar. From 130 days of gestation to postnatal ages, growth of dendrites of elongate neurons plateaued or declined, whereas dendrites of multipolar neurons apparently continued to increase in size and extent. In addition, spine density decreased on elongate neurons but remained stable on multipolar neurons. Morphological variables of ovoid cells, proposed interneurons in NST, did not alter over this later period. The data suggest that multipolar, not elongate or ovoid, neurons are logical candidates to receive the increasing afferent fiber input onto NST cells during late gestation. Also, neural activity from taste afferent fibers is more likely to have a role in altering NST neuron morphology at later, rather than earlier, developmental periods. © 1994 Wiley‐Liss, Inc.
Neuroactive substances in the developing dorsomedial telencephalon of the pigeon (Columba livia): Differential distribution and time course of maturation
Authors: Erichsen Jonathan T. , Ciocchetti Andrea , Fontanesi Gigliola , Bagnoli Paola
Published: January 2005

The avian hippocampal formation has previously been shown to contain many of the same neurotransmitters and related enzymes that are found in mammals. In order to determine whether the relatively delayed development of the mammalian hippocampus is typical of other vertebrates, we investigated the maturation of a variety of heuroactive substances in the hippocampal formation of the homing pigeon. The distribution of two transmitter‐related enzymes, choline acetyltransferase (ChAT) and tyrosine hydroxylase (TH), the neurotransmitter GABA, and four neuropeptides (substance P, enkephalin, neuropeptide Y, and somatostatin) was studied by immniunohistochemistry in the developing hippocampal complex. The pattern and/or the time course of changes in the distribution of immunoreactivity varied among the different neuroactive substances examined. Immunoreactivity to ChAT and TH was found exclusively in fibers and terminal‐like processes, whereas GABA and peptide immunoreactivity was seen in cells and neuropil. Quantitative differences in the density, number, and size of stained cells were assessed by a computer‐assisted image analyzer. For the majority of the substances, developmental patterns in the distribution of immunoreactivity differ between the hippocampus proper and the area parahippocampalis, the two major areas that together make up the avian hippocampal complex. The adult pattern of immunoreactivity was generally attained by 3 weeks after hatching. For many of the neuroactive substances found in cell bodies, there was a gradual decrease in the density of immunoreactive cells with a concomitant increase in the density of immunoreactive neuropil. The actual number of stained cells usually increased to a peak at 9 days posthatching and then declined until 3 weeks posthatching, when the adult value was reached. These results are discussed in relation to the advantages that the pigeon hippocampal complex may provide in the study of developmental processes. Parallels with the distribution of the same neuroactive substances in the mammalian hippocampus are used to suggest possible functional similarities between the avian and mammalian hippocampal regions. © 1994 Wiley‐Liss, Inc.